[goldwerger]

Hope SoCal was good. I'll be in Dallas this year as it's close by.

Planning to go to Dallas if my son's college application deadlines (for which I slave with him) will let me escape for a weekend of sanity... refundable hotel and flights booked, crossing fingers...

 

[GridIroN]

Hello fellow humans.

I have the opportunity to own both the infamous Icon Audio HP8 Mk.II Signature as well as the Cayin HA-3A tube amplifiers. These units are ZMF lovers favourites. I personally had a lot of questions about how they compare when deciding to get into tubes, and I noticed throughout a good number of threads, quite a few others had questions as well. I couldn't find anywhere else on the interweb where the HP8 was compared in depth, and there are only one or two english reviews. Well, now I own both, and have the opportunity to give a brief overview of the differences. Both units are using their default tubes (no tube rolling yet).



Tested on:

• ZMF Caldera, using default ZMF caldera medium lambskin pads.
• ZMF Atrium Open, using ZMF auteur hybrid pads.
• Focal Clear using ZMF Suede Sub pads.

The HP8 only offers 6.35mm single-ended and a Youkamoo adapter which appeared to have no impact on sound signal or quality. The Cayin was heard through balanced XLR and 4.4mm.

The Cayin HA-3A​

My Cayin was was made in 2022 and is the “B” version that uses a different set of default tubes (EH 6v6, JJ 12au7, RCA 25AX4GT). It's noise floor is predominantly black on low impedance setting. Was not expecting that as the Cayin HA-XA series is known for issues with impedance matching and noise. I can hear a bit of noise on medium and a bit more on high, but the ambient noise of traffic outside is more noticeable than the noise coming through the connection. Also tested my 12.6ohm Unique Melody MEST Mk.II’s in the 4.4mm/low imp. And again heard minor hum (if I really listened for it) on low. The noise floor rose to audible levels on medium and high.

Sonic characteristics (+vs the HP8 Mk.II):

• First thing that comes to mind is “layered air”
• Surprisingly girthy sound. Especially up top.
• Much slower decay than the HP8, but somehow doesn’t translate to sounding slower.
• More of an edge on it than the HP8; HP8 sounds bolder, but the notes have softer edges.
• Ever so slightly bigger soundstage vs the HP8 (like 10~15%, maybe)
• Character of the HA-3A is fast, and lively. Seems in contradiction to some people’s description as “delicate” or “nuanced”. I don’t know that I’d use either of those words to describe what I’m hearing.
• Bass feels airier than the HP8, and more present, but less controlled. It’s funner, but more fatiguing.
• Midrange sounds less well imaged than the HP8. HA-3 can get congested.
• Less concerned with articulation, instead aiming for a specific rich-of-neutral tube timbre
• Again, intensely layered sound. Can almost touch the layers of air; well defined soundstage
• Switching to the Atrium open, the headphone now sounds slowed down. A romantic headphone now sounds moreso
• What the HA-3 wants to do is translated perfectly to the Atrium O. The experience is rich, dynamic, and even more lush.
• The upper range has more presence, locality and sparkle. The HP8 does this also, but the Cayin has even more. The biggest surprise thus far.
  • SIGNIFICANT texture boost.
• The Focal Clear didn't really like this amp IMO. Not that it did badly, but the amp somewhat muddied the presentation, at least with the factory set of tubes. I don't think anyone who bought and likes the Focal Clear is after this sound signature for what the Clear does with sound.
  • I can imagine this reversing with brighter tubes.

The HP8 Mk.II Signature edition​

My HP8 was made March 29th, 2023. It's equipped with the default set of tubes (Electro Harmonix 12AX7, 2x David Shaw Signature CV181 (6SN7)'s). Listened with no music, I hear no noise on the floor whatsoever; it's pitch black. That being said, I have noticed the right tube is slightly noisier than the left. Every now and then, it starts "fuzzing" for a minute or two, but this goes away. It is probably picking up a signal from something (?).

Sonic characteristics (+vs the HA-3A):

• Bold, yet soft. Very full bodied. I can’t imagine anyone wanting a SS vs this.
• Somewhat wider portrayal of the FR versus the HA-3; The HP8 can be more delicate. Quiet segments are quieter, loud segments are louder & more forceful.
• Soundstage is slightly smaller but more localized; less air, but traded for more holography. It wants you to enjoy the music, but it still wants to impress you.
• More sparkle on the top end; highs have a crystalline nature, and whilst the HA-3 has a slower roll off, the power of those high notes stays with you a moment longer.
• Articulate, yet smooth. The HP8 is in fact addictively smooth, generally great and extremely inoffensive.
• Many people seem to prefer the medium impedance setting with the HP8. I found medium made the sound signature very forward and sometimes very unpleasant. For some of my test-tracks, the soundstage disappeared and I felt like I was trapped in an elevator with the band. Low impedance with a higher listening volume seemed to do a better job preserving the character of the music.
• This however was not the case with the Atrium Open. WOW is the word. Medium did a much better job of powering the 300ohm dynamic, and the HP8's accurate, bold, and confident timbre did the AO WONDERS. For a headphone that doesn't change much via source, It was a clear upgrade for the Atrium.
• The Atrium kept it's original warmer, and romantic timbre, but now benefited from a mild soundstage boost, and was a little sharper in the imaging. Again, the initial attack of the notes just wanted to stay with you a moment longer making the Atrium sound not only inviting and romantic, but bolder, stronger, and more muscular.
  • The top end also received a sparkle boost, but not as much as the HA-3.
• Switching to the Focal Clear, it again sounded much better on the HP8. No contest. The timbre of the HP8 is just far more suited to the fast, punchy, resolving nature of the HP8. The HA-3 in comparison sounded like it wanted to Focal to do something that wasn't in it's wheelhouse.

After thinking about it for a while, I really was able to put into words the difference between the two tube amps, and I really do think it’s accurate: The HA-3 makes everything sound like a live performance. It makes you feel like you’re at the bar and listening to the band play on stage. The HP8 in comparison, sounds like you’re at a theatre. Not in terms of soundstage, but in terms of the character of It’s sounds which I’d peg as almost…”professional” in comparison.

The HP8’s body is smoother, and more articulate. But, the HA-3 has a forwardness to it’s texture you don’t get from the HP8, at least not with it’s default tubes.

This all being said, I absolutely understand why people would feel the HP8 is the better amp. It’s an excellent, somewhat more traditional sound that doesn’t make anything sound bad, and makes everything sound amazing. It has literally no downsides that I can hear. It's entirely possible to buy this amp, never modify it at all, and be happy for the rest of your ownership.

The HA-3 on the other hand took me to different places that I couldn't believe (this amp made me cry...). But, at the same time there were also 2 or 3 songs I came across in my collection that the amp didn’t do anything for whilst I thought this song blew my mind on the HP8. The HP8 was immediately amazing, where as my first reaction when turning the HA-3 on was “...Oh?...ok…” until I realized what it was trying to do. In comparison to the HP8, if you bought the HA-3 I would say it would be best to tube roll.

Ultimately, neither amp is the obvious best, I think both amps are actually surprisingly different, which was entirely unexpected.

All of this being said, I’m planning my NOS tube purchases as we speak… HA-3A goes first...going to see if I can get it a step closer to the HP8's signature without losing what the HA-3 does best.

I said I would update the thread with some tube roll impressions to go along with my brief review of both the Cayin HA-3A and the Icon Audio HP8 Mk.II Signature Edition. I purchased a significant collection of tubes locally, all NOS. I've spent about 2 days getting acquainted with what each tube offers. I found a lot of combinations produced similar results, but I've tried not to sound repetitive.

Tube Rolling the Cayin HA-3A​

Starting off on the HA-3A, brief word on the 12AU7 signal tubes: I decided to replace the factory JJ's with E80CC's. Firstly, they look bomb, second, they are famously great sounding tubes so I figured they'd be an obvious first attempt. I wasn't disappointed, they sound fantastic, with a beautiful representation throughout the whole frequency range with nothing sounding biased or out of place. No real need to roll anything more.

On to 6v6 slot tubes...!

Tungsram E80CC’s + Marconi 6v6G "Cokebottles"​

• Good mid tone
• Great body
• Warm “live” sound is gone, replaced with a more traditional sound
• Very smooth transients
• Significant soundstage boost
• Significant treble extension boost
• Note attack significantly less. Significantly reduction of sub-bass
• Detailed, forward midrange
• Very nice holography and separation

Overall, a smooth, mellow, agile combination. Mid~treble focus. Wouldn't generally be my first choice in terms of timbre, but it's very nice.

Tungsram E80CC’s + National Union (SovTek) 6v6GTA's​

• Full bodied
• Clear, and VERY crisp
• Particularly detailed
• Holography and imaging upgrade noticeable
• Bass punch is nice
• Otherwise very neutral

Overall, a fast paced, and highly dynamic; wonderfully neutral.

Both sets of tubes represent a significant improvements over the factory tube set in terms of general listenability. The factory sound as I said previously, was really trying to produce a lively, "live" sound. Both sets of NOS tubes I tried presented more well-rounded, traditional sound profile. I personally and surprisingly felt the Soviet National Union tubes were best and will be using them as my every-day tube roll.

It’s also important to note that all sets of tubes significantly lowered the noise floor. A significant portion of the hum present in the HA-3A seems to come from the not-fantastic modern tubes. That's taking into consideration the E80CC's have more gain than the factory 12Aau7's.

Tube Rolling the Icon Audio HP8 MK.II Signature Edition​

I purchased a few different signal tubes, and received an old Telefunken tube from the extremely generous @Pharmaboy. I purchased a NOS Raytheon military AT7WC, and a NOS Sylvania military AT7WC. Both tubes test higher than normal gain for their type. All 3 tubes were free of microphonics.

Telefunken 12AX7 (NOS West Germany, year unknown)​

• Incredibly bold sound +++
• Articulate ++
• Edgy, tense.

All around superior to the factory ElectroHarmonix. Basically an automatic upgrade for the whole sound profile.

Sylvania JAN 12AT7WC 1979​

• Very smooth
• Tad more air than the Raytheon
• Very nice sparkle up top. Makes up for the trade away of lower end impact.

A tube so mellow, it is perhaps too much so, but can sound good when paired with a complimentary tube.

Raytheon JAN 12AT7WC 1974​

• Very loud for an AT7. Higher mU than expected
• Nicely detailed, very “fine” sound, but rather forward.
• Nice little bump in treble extension
• Adds a bit of decay to the mix.

Nice overall tube that adds a TOUCH of romance, but is overall still clear, crisp, neutral, and impactful. This tube makes the HP8 sound a bit more like the rustic, live sounding profile the HA-3 has from the factory.

Tung-Sol 6SN7GTB “Tall Boys” 1959​

(With Sylvania 12AT7WC)

• Well extended upper and mid range
• Crisp
• Layered
• Details, details, details
• Soundstage depth increase; lots of space between notes
• Bass kick is there, but subbass presence is significantly recessed

TungSol’s give the Sylvania a bit more kick back, but the low end is over-all fast, dynamic, hyper controlled. Not a bass-head combination, but doesn’t sound offensively anemic. Wouldn't be my first choice though.

(With Raytheon 12AT7WC)

• Very complimentary tube selection
• A light, heavenly 'sing-song' sound yet still somehow rich
• Agile. Both tubes sets are quite dynamic, so they boost each other nicely.
• Extension; both tube sets have a touch of extension on the mid/upper mid range.
• Romance; a slower decay at the mid/upper mid range keeps this tube set from sounding overly clinical or “solid state”.

Potentially end-game tube combination for this amp

(With Telefunken 12AX7)

• Lots of space between notes
• Still has a lot of detail
• Punch from the telefunken is very welcome, produces a dynamic and balanced combo
• Nice bass
• Takes the holography from the telefunken and merges it with the detail retrieval of the tungsol.
• Incredible combination.

Overall a great combo. Very much similar tone to the factory sound of the HP8 but risen to a new level, and with attitude.

Sylvania 7N7 rebased to 6SN7GT “Bad Boy” Chrome Domes​

(With Sylvania tube 12AT7WC)

• Detailed & crystalline. Amazing upper range
• Faster roll off than the Tung-Sols
• Nice bass kick
• Subbass feels a tad veiled, & thin; doesn’t sound bad, but leaves you wanting in the lower register.
• Wonderful textured mid range however...
• Airier lower mid range than the Tungsols

Overall a smoother, dark-of-neutral tone with nice air and texture. Again, would not be my first choice though...

(With Raytheon 12AT7WC)

• A more balanced presentation
• Subbass kick
• Impact and note weight
• Mildly mid-forward

Overall a very pleasant, balanced combination. A close 2nd to the next one...

(With Telefunken 12AX7)

• Warm with lots of air
• Full bodied & splashy
• Crazy holography
• Mind-blowing

Story time... I was previously listening on the low gain amp option on the HP8 as my previous review noted I strongly disliked the other gain options. When I first listened to this combination, I didn't like it much. It sounded veiled and...mushy. Something prompted me to see what happens if I increase the gain because I thought "there's no way that's what these tubes sound like. I put a lot of research into these tubes...these should be great". Well, I turned the knob and then.... the clouds parted and the gods spoke to me through the voices of my ancestors and I bore witness to a sound unlike anything I have heard before. I then took a 2nd day to re-review everything I had heard on higher gain. The other tubes did not change much.

Comparing the final tube roll of both the HA-3A and the HP8 SE​

I ended up with a sound I loved respectively from both amps. Both amps are nowhere near their top potential in their factory form, though I would say it's my experience having now experimented on both it is easier, and much cheaper to raise up the HA-3A than the HP8, but the HP8 with good tubes is on a level I do not think the HA-3A can match. Close? Yes, but match? I don't think so. I also think the HA-3A's sound signature changes far more readily and quickly than the HP8. The HP8's sound signature is heavily reliant on the single 12AX7 tube. I tried leaving the factory David Shaw CV181's in, and the sound was still much improved; the DS 181's are well chosen, clean, revealing, transparent and articulate tubes. On the HA-3 I get the impression it would be fine to seek 12AU7's that are crisp, clean and leave it at that. The 6v6's are more than capable of producing a pleasing shift in sound if a user wanted to be conservative with their money. It was VERY expensive to bring up the sound of the HP8 in comparison.

Next I will try some different 12AX7's in the HP8 and see what happens. I have a hunch the reason the AT7's both sounded on the thin side was because the amp really was designed for an AX7 to be driving it.

 

[Pharmaboy]

I said I would update the thread with some tube roll impressions to go along with my brief review of both the Cayin HA-3A and the Icon Audio HP8 Mk.II Signature Edition. I purchased a significant collection of tubes locally, all NOS. I've spent about 2 days getting acquainted with what each tube offers. I found a lot of combinations produced similar results, but I've tried not to sound repetitive.

Tube Rolling the Cayin HA-3A​

Starting off on the HA-3A, brief word on the 12AU7 signal tubes: I decided to replace the factory JJ's with E80CC's. Firstly, they look bomb, second, they are famously great sounding tubes so I figured they'd be an obvious first attempt. I wasn't disappointed, they sound fantastic, with a beautiful representation throughout the whole frequency range with nothing sounding biased or out of place. No real need to roll anything more.

On to 6v6 slot tubes...!

Tungsram E80CC’s + Marconi 6v6G "Cokebottles"​

• Good mid tone
• Great body
• Warm “live” sound is gone, replaced with a more traditional sound
• Very smooth transients
• Significant soundstage boost
• Significant treble extension boost
• Note attack significantly less. Significantly reduction of sub-bass
• Detailed, forward midrange
• Very nice holography and separation

Overall, a smooth, mellow, agile combination. Mid~treble focus. Wouldn't generally be my first choice in terms of timbre, but it's very nice.

Tungsram E80CC’s + National Union (SovTek) 6v6GTA's​

• Full bodied
• Clear, and VERY crisp
• Particularly detailed
• Holography and imaging upgrade noticeable
• Bass punch is nice
• Otherwise very neutral

Overall, a fast paced, and highly dynamic; wonderfully neutral.

Both sets of tubes represent a significant improvements over the factory tube set in terms of general listenability. The factory sound as I said previously, was really trying to produce a lively, "live" sound. Both sets of NOS tubes I tried presented more well-rounded, traditional sound profile. I personally and surprisingly felt the Soviet National Union tubes were best and will be using them as my every-day tube roll.

It’s also important to note that all sets of tubes significantly lowered the noise floor. A significant portion of the hum present in the HA-3A seems to come from the not-fantastic modern tubes. That's taking into consideration the E80CC's have more gain than the factory 12Aau7's.

Tube Rolling the Icon Audio HP8 MK.II Signature Edition​

I purchased a few different signal tubes, and received an old Telefunken tube from the extremely generous @Pharmaboy. I purchased a NOS Raytheon military AT7WC, and a NOS Sylvania military AT7WC. Both tubes test higher than normal gain for their type. All 3 tubes were free of microphonics.

Telefunken 12AX7 (NOS West Germany, year unknown)​

• Incredibly bold sound +++
• Articulate ++
• Edgy, tense.

All around superior to the factory ElectroHarmonix. Basically an automatic upgrade for the whole sound profile.

Sylvania JAN 12AT7WC 1979​

• Very smooth
• Tad more air than the Raytheon
• Very nice sparkle up top. Makes up for the trade away of lower end impact.

A tube so mellow, it is perhaps too much so, but can sound good when paired with a complimentary tube.

Raytheon JAN 12AT7WC 1974​

• Very loud for an AT7. Higher mU than expected
• Nicely detailed, very “fine” sound, but rather forward.
• Nice little bump in treble extension
• Adds a bit of decay to the mix.

Nice overall tube that adds a TOUCH of romance, but is overall still clear, crisp, neutral, and impactful. This tube makes the HP8 sound a bit more like the rustic, live sounding profile the HA-3 has from the factory.

Tung-Sol 6SN7GTB “Tall Boys” 1959​

(With Sylvania 12AT7WC)

• Well extended upper and mid range
• Crisp
• Layered
• Details, details, details
• Soundstage depth increase; lots of space between notes
• Bass kick is there, but subbass presence is significantly recessed

TungSol’s give the Sylvania a bit more kick back, but the low end is over-all fast, dynamic, hyper controlled. Not a bass-head combination, but doesn’t sound offensively anemic. Wouldn't be my first choice though.

(With Raytheon 12AT7WC)

• Very complimentary tube selection
• A light, heavenly 'sing-song' sound yet still somehow rich
• Agile. Both tubes sets are quite dynamic, so they boost each other nicely.
• Extension; both tube sets have a touch of extension on the mid/upper mid range.
• Romance; a slower decay at the mid/upper mid range keeps this tube set from sounding overly clinical or “solid state”.

Potentially end-game tube combination for this amp

(With Telefunken 12AX7)

• Lots of space between notes
• Still has a lot of detail
• Punch from the telefunken is very welcome, produces a dynamic and balanced combo
• Nice bass
• Takes the holography from the telefunken and merges it with the detail retrieval of the tungsol.
• Incredible combination.

Overall a great combo. Very much similar tone to the factory sound of the HP8 but risen to a new level, and with attitude.

Sylvania 7N7 rebased to 6SN7GT “Bad Boy” Chrome Domes​

(With Sylvania tube 12AT7WC)

• Detailed & crystalline. Amazing upper range
• Faster roll off than the Tung-Sols
• Nice bass kick
• Subbass feels a tad veiled, & thin; doesn’t sound bad, but leaves you wanting in the lower register.
• Wonderful textured mid range however...
• Airier lower mid range than the Tungsols

Overall a smoother, dark-of-neutral tone with nice air and texture. Again, would not be my first choice though...

(With Raytheon 12AT7WC)

• A more balanced presentation
• Subbass kick
• Impact and note weight
• Mildly mid-forward

Overall a very pleasant, balanced combination. A close 2nd to the next one...

(With Telefunken 12AX7)

• Warm with lots of air
• Full bodied & splashy
• Crazy holography
• Mind-blowing

Story time... I was previously listening on the low gain amp option on the HP8 as my previous review noted I strongly disliked the other gain options. When I first listened to this combination, I didn't like it much. It sounded veiled and...mushy. Something prompted me to see what happens if I increase the gain because I thought "there's no way that's what these tubes sound like. I put a lot of research into these tubes...these should be great". Well, I turned the knob and then.... the clouds parted and the gods spoke to me through the voices of my ancestors and I bore witness to a sound unlike anything I have heard before. I then took a 2nd day to re-review everything I had heard on higher gain. The other tubes did not change much.

Comparing the final tube roll of both the HA-3A and the HP8 SE​

I ended up with a sound I loved respectively from both amps. Both amps are nowhere near their top potential in their factory form, though I would say it's my experience having now experimented on both it is easier, and much cheaper to raise up the HA-3A than the HP8, but the HP8 with good tubes is on a level I do not think the HA-3A can match. Close? Yes, but match? I don't think so. I also think the HA-3A's sound signature changes far more readily and quickly than the HP8. The HP8's sound signature is heavily reliant on the single 12AX7 tube. I tried leaving the factory David Shaw CV181's in, and the sound was still much improved; the DS 181's are well chosen, clean, revealing, transparent and articulate tubes. On the HA-3 I get the impression it would be fine to seek 12AU7's that are crisp, clean and leave it at that. The 6v6's are more than capable of producing a pleasing shift in sound if a user wanted to be conservative with their money. It was VERY expensive to bring up the sound of the HP8 in comparison.

Next I will try some different 12AX7's in the HP8 and see what happens. I have a hunch the reason the AT7's both sounded on the thin side was because the amp really was designed for an AX7 to be driving it.

This tube review reads like a short story, complete with characters, a dynamic plot, and revelations as the plot develops. My favorite part is "Story time..."

Apparently there will be a sequel:

Next I will try some different 12AX7's in the HP8 and see what happens.

I find this post to be very well written and thought out. It makes me wonder about the path I chose not to go down with my HP8: using 12AX7 input tubes. I had good reasons to not use 12AX7s (see below).

Background: The HP8 lives in my main system (speakers/sub + headphones) which has had excess gain issues ever since I started using a wonderful sounding DAC, the MHDT Labs Orchid, which outputs 3.0 volts single-ended, 50% more than the nominal 2.0 volt output standard. Perhaps because of that, I find that the lower gain 12AT7 and 5751 input tubes produce an overall more pleasant and manageable sound than the 12AX7 the amp was designed with.

FWIW, the input tube that currently impresses me the most on the HP8 is the Raytheon CK5751 given me by another Head-Fi friend and HP8 owner. 5751s have a bit more gain than the very nice-sounding 12AT7s I usually use:

• 5751 has 70% of the gain of a 12AX7
• 12AT7 has 60% of the gain of a 12AX7

However, after reading this post, I wonder how 12AX7s would sound if my HP8 was connected to a single-ended DAC putting out something closer to 2.0 volts. It's easy to test this, as I have two systems. The 2nd/side system (headphones only) has a different DAC with a lower output. I'll have to check out the HP8 with 12AX7s in that system.

That we can get good sonic results with 3 different classes of input tubes is a tribute to the flexibility & solidity of the HP8 design...

 

[crakers7]

I said I would update the thread with some tube roll impressions to go along with my brief review of both the Cayin HA-3A and the Icon Audio HP8 Mk.II Signature Edition. I purchased a significant collection of tubes locally, all NOS. I've spent about 2 days getting acquainted with what each tube offers. I found a lot of combinations produced similar results, but I've tried not to sound repetitive.

Tube Rolling the Cayin HA-3A​

Starting off on the HA-3A, brief word on the 12AU7 signal tubes: I decided to replace the factory JJ's with E80CC's. Firstly, they look bomb, second, they are famously great sounding tubes so I figured they'd be an obvious first attempt. I wasn't disappointed, they sound fantastic, with a beautiful representation throughout the whole frequency range with nothing sounding biased or out of place. No real need to roll anything more.

On to 6v6 slot tubes...!

Tungsram E80CC’s + Marconi 6v6G "Cokebottles"​

• Good mid tone
• Great body
• Warm “live” sound is gone, replaced with a more traditional sound
• Very smooth transients
• Significant soundstage boost
• Significant treble extension boost
• Note attack significantly less. Significantly reduction of sub-bass
• Detailed, forward midrange
• Very nice holography and separation

Overall, a smooth, mellow, agile combination. Mid~treble focus. Wouldn't generally be my first choice in terms of timbre, but it's very nice.

Tungsram E80CC’s + National Union (SovTek) 6v6GTA's​

• Full bodied
• Clear, and VERY crisp
• Particularly detailed
• Holography and imaging upgrade noticeable
• Bass punch is nice
• Otherwise very neutral

Overall, a fast paced, and highly dynamic; wonderfully neutral.

Both sets of tubes represent a significant improvements over the factory tube set in terms of general listenability. The factory sound as I said previously, was really trying to produce a lively, "live" sound. Both sets of NOS tubes I tried presented more well-rounded, traditional sound profile. I personally and surprisingly felt the Soviet National Union tubes were best and will be using them as my every-day tube roll.

It’s also important to note that all sets of tubes significantly lowered the noise floor. A significant portion of the hum present in the HA-3A seems to come from the not-fantastic modern tubes. That's taking into consideration the E80CC's have more gain than the factory 12Aau7's.

Tube Rolling the Icon Audio HP8 MK.II Signature Edition​

I purchased a few different signal tubes, and received an old Telefunken tube from the extremely generous @Pharmaboy. I purchased a NOS Raytheon military AT7WC, and a NOS Sylvania military AT7WC. Both tubes test higher than normal gain for their type. All 3 tubes were free of microphonics.

Telefunken 12AX7 (NOS West Germany, year unknown)​

• Incredibly bold sound +++
• Articulate ++
• Edgy, tense.

All around superior to the factory ElectroHarmonix. Basically an automatic upgrade for the whole sound profile.

Sylvania JAN 12AT7WC 1979​

• Very smooth
• Tad more air than the Raytheon
• Very nice sparkle up top. Makes up for the trade away of lower end impact.

A tube so mellow, it is perhaps too much so, but can sound good when paired with a complimentary tube.

Raytheon JAN 12AT7WC 1974​

• Very loud for an AT7. Higher mU than expected
• Nicely detailed, very “fine” sound, but rather forward.
• Nice little bump in treble extension
• Adds a bit of decay to the mix.

Nice overall tube that adds a TOUCH of romance, but is overall still clear, crisp, neutral, and impactful. This tube makes the HP8 sound a bit more like the rustic, live sounding profile the HA-3 has from the factory.

Tung-Sol 6SN7GTB “Tall Boys” 1959​

(With Sylvania 12AT7WC)

• Well extended upper and mid range
• Crisp
• Layered
• Details, details, details
• Soundstage depth increase; lots of space between notes
• Bass kick is there, but subbass presence is significantly recessed

TungSol’s give the Sylvania a bit more kick back, but the low end is over-all fast, dynamic, hyper controlled. Not a bass-head combination, but doesn’t sound offensively anemic. Wouldn't be my first choice though.

(With Raytheon 12AT7WC)

• Very complimentary tube selection
• A light, heavenly 'sing-song' sound yet still somehow rich
• Agile. Both tubes sets are quite dynamic, so they boost each other nicely.
• Extension; both tube sets have a touch of extension on the mid/upper mid range.
• Romance; a slower decay at the mid/upper mid range keeps this tube set from sounding overly clinical or “solid state”.

Potentially end-game tube combination for this amp

(With Telefunken 12AX7)

• Lots of space between notes
• Still has a lot of detail
• Punch from the telefunken is very welcome, produces a dynamic and balanced combo
• Nice bass
• Takes the holography from the telefunken and merges it with the detail retrieval of the tungsol.
• Incredible combination.

Overall a great combo. Very much similar tone to the factory sound of the HP8 but risen to a new level, and with attitude.

Sylvania 7N7 rebased to 6SN7GT “Bad Boy” Chrome Domes​

(With Sylvania tube 12AT7WC)

• Detailed & crystalline. Amazing upper range
• Faster roll off than the Tung-Sols
• Nice bass kick
• Subbass feels a tad veiled, & thin; doesn’t sound bad, but leaves you wanting in the lower register.
• Wonderful textured mid range however...
• Airier lower mid range than the Tungsols

Overall a smoother, dark-of-neutral tone with nice air and texture. Again, would not be my first choice though...

(With Raytheon 12AT7WC)

• A more balanced presentation
• Subbass kick
• Impact and note weight
• Mildly mid-forward

Overall a very pleasant, balanced combination. A close 2nd to the next one...

(With Telefunken 12AX7)

• Warm with lots of air
• Full bodied & splashy
• Crazy holography
• Mind-blowing

Story time... I was previously listening on the low gain amp option on the HP8 as my previous review noted I strongly disliked the other gain options. When I first listened to this combination, I didn't like it much. It sounded veiled and...mushy. Something prompted me to see what happens if I increase the gain because I thought "there's no way that's what these tubes sound like. I put a lot of research into these tubes...these should be great". Well, I turned the knob and then.... the clouds parted and the gods spoke to me through the voices of my ancestors and I bore witness to a sound unlike anything I have heard before. I then took a 2nd day to re-review everything I had heard on higher gain. The other tubes did not change much.

Comparing the final tube roll of both the HA-3A and the HP8 SE​

I ended up with a sound I loved respectively from both amps. Both amps are nowhere near their top potential in their factory form, though I would say it's my experience having now experimented on both it is easier, and much cheaper to raise up the HA-3A than the HP8, but the HP8 with good tubes is on a level I do not think the HA-3A can match. Close? Yes, but match? I don't think so. I also think the HA-3A's sound signature changes far more readily and quickly than the HP8. The HP8's sound signature is heavily reliant on the single 12AX7 tube. I tried leaving the factory David Shaw CV181's in, and the sound was still much improved; the DS 181's are well chosen, clean, revealing, transparent and articulate tubes. On the HA-3 I get the impression it would be fine to seek 12AU7's that are crisp, clean and leave it at that. The 6v6's are more than capable of producing a pleasing shift in sound if a user wanted to be conservative with their money. It was VERY expensive to bring up the sound of the HP8 in comparison.

Next I will try some different 12AX7's in the HP8 and see what happens. I have a hunch the reason the AT7's both sounded on the thin side was because the amp really was designed for an AX7 to be driving it.

Great review , In your photo the the E80CC say Telefunken not Tungsram , are they the same tube ?

 

[GridIroN]

This tube review reads like a short story, complete with characters, a dynamic plot, and revelations as the plot develops. My favorite part is "Story time..."

Apparently there will be a sequel:


I find this post to be very well written and thought out. It makes me wonder about the path I chose not to go down with my HP8: using 12AX7 input tubes. I had good reasons to not use 12AX7s (see below).

Background: The HP8 lives in my main system (speakers/sub + headphones) which has had excess gain issues ever since I started using a wonderful sounding DAC, the MHDT Labs Orchid, which outputs 3.0 volts single-ended, 50% more than the nominal 2.0 volt output standard. Perhaps because of that, I find that the lower gain 12AT7 and 5751 input tubes produce an overall more pleasant and manageable sound than the 12AX7 the amp was designed with.

FWIW, the input tube that currently impresses me the most on the HP8 is the Raytheon CK5751 given me by another Head-Fi friend and HP8 owner. 5751s have a bit more gain than the very nice-sounding 12AT7s I usually use:

• 5751 has 70% of the gain of a 12AX7
• 12AT7 has 60% of the gain of a 12AX7

However, after reading this post, I wonder how 12AX7s would sound if my HP8 was connected to a single-ended DAC putting out something closer to 2.0 volts. It's easy to test this, as I have two systems. The 2nd/side system (headphones only) has a different DAC with a lower output. I'll have to check out the HP8 with 12AX7s in that system.

That we can get good sonic results with 3 different classes of input tubes is a tribute to the flexibility & solidity of the HP8 design...

Hah thanks man!

For what it's worth I'm using a Modi 3 as my DAC, my amps are hooked up to a very non-optimal power bar and there's lots of potential for noise where my table is (WiFi, phone signals, lots of electronics in this corner) and as I said, changing out the tubes mostly resulted is massive reductions or elimination of noise.

My guess is your noise is probably coming from your chain somewhere, and could very much be the DAC itself, sure.

 

[GridIroN]

Great review , In your photo the the E80CC say Telefunken not Tungsram , are they the same tube ?

Yup. They're Telefunken branded Tungsrams. Same tube though.

The two 6v6 tubes are also both Marconi 6v6Gs. One is just branded General Electric.

 

[dpeterfy32]

I am planning to buy dynamic headphones for my feliks audio euforia evo amplifier. I am thinking between zmf atrium and focal utopia 2022. what do you think?
I play games, watch movies, videos, stream, listen to music in all genres. so you need an all-rounder multimedia sound.

 

[GridIroN]

I am planning to buy dynamic headphones for my feliks audio euforia evo amplifier. I am thinking between zmf atrium and focal utopia 2022. what do you think?
I play games, watch movies, videos, stream, listen to music in all genres. so you need an all-rounder multimedia sound.

I have successfully used a ZMF Atrium and a Focal Clear (baby Utopia) as my everyday-driver. It's more a matter of preference as they sound quite different.

 

[senseitedj]

I am planning to buy dynamic headphones for my feliks audio euforia evo amplifier. I am thinking between zmf atrium and focal utopia 2022. what do you think?
I play games, watch movies, videos, stream, listen to music in all genres. so you need an all-rounder multimedia sound.

I think a ZMF atrium would be the better all-rounder. Particularly the closed-back version.

Not saying utopia is bad, but you will find the presentation of the Utopia to be a little bit too intrusive and enjoying general media to be fatiguing.

The atrium closed provides a good blend of technicality and delivers details in a laid-back manner, so you will not get tired of long listening sessions.

It is for these reasons I chose the atrium closed to complement my Audeze LCD-4z.

 

[Rollnrock]

I said I would update the thread with some tube roll impressions to go along with my brief review of both the Cayin HA-3A and the Icon Audio HP8 Mk.II Signature Edition. I purchased a significant collection of tubes locally, all NOS. I've spent about 2 days getting acquainted with what each tube offers. I found a lot of combinations produced similar results, but I've tried not to sound repetitive.

Tube Rolling the Cayin HA-3A​

Starting off on the HA-3A, brief word on the 12AU7 signal tubes: I decided to replace the factory JJ's with E80CC's. Firstly, they look bomb, second, they are famously great sounding tubes so I figured they'd be an obvious first attempt. I wasn't disappointed, they sound fantastic, with a beautiful representation throughout the whole frequency range with nothing sounding biased or out of place. No real need to roll anything more.

On to 6v6 slot tubes...!

Tungsram E80CC’s + Marconi 6v6G "Cokebottles"​

• Good mid tone
• Great body
• Warm “live” sound is gone, replaced with a more traditional sound
• Very smooth transients
• Significant soundstage boost
• Significant treble extension boost
• Note attack significantly less. Significantly reduction of sub-bass
• Detailed, forward midrange
• Very nice holography and separation

Overall, a smooth, mellow, agile combination. Mid~treble focus. Wouldn't generally be my first choice in terms of timbre, but it's very nice.

Tungsram E80CC’s + National Union (SovTek) 6v6GTA's​

• Full bodied
• Clear, and VERY crisp
• Particularly detailed
• Holography and imaging upgrade noticeable
• Bass punch is nice
• Otherwise very neutral

Overall, a fast paced, and highly dynamic; wonderfully neutral.

Both sets of tubes represent a significant improvements over the factory tube set in terms of general listenability. The factory sound as I said previously, was really trying to produce a lively, "live" sound. Both sets of NOS tubes I tried presented more well-rounded, traditional sound profile. I personally and surprisingly felt the Soviet National Union tubes were best and will be using them as my every-day tube roll.

It’s also important to note that all sets of tubes significantly lowered the noise floor. A significant portion of the hum present in the HA-3A seems to come from the not-fantastic modern tubes. That's taking into consideration the E80CC's have more gain than the factory 12Aau7's.

Tube Rolling the Icon Audio HP8 MK.II Signature Edition​

I purchased a few different signal tubes, and received an old Telefunken tube from the extremely generous @Pharmaboy. I purchased a NOS Raytheon military AT7WC, and a NOS Sylvania military AT7WC. Both tubes test higher than normal gain for their type. All 3 tubes were free of microphonics.

Telefunken 12AX7 (NOS West Germany, year unknown)​

• Incredibly bold sound +++
• Articulate ++
• Edgy, tense.

All around superior to the factory ElectroHarmonix. Basically an automatic upgrade for the whole sound profile.

Sylvania JAN 12AT7WC 1979​

• Very smooth
• Tad more air than the Raytheon
• Very nice sparkle up top. Makes up for the trade away of lower end impact.

A tube so mellow, it is perhaps too much so, but can sound good when paired with a complimentary tube.

Raytheon JAN 12AT7WC 1974​

• Very loud for an AT7. Higher mU than expected
• Nicely detailed, very “fine” sound, but rather forward.
• Nice little bump in treble extension
• Adds a bit of decay to the mix.

Nice overall tube that adds a TOUCH of romance, but is overall still clear, crisp, neutral, and impactful. This tube makes the HP8 sound a bit more like the rustic, live sounding profile the HA-3 has from the factory.

Tung-Sol 6SN7GTB “Tall Boys” 1959​

(With Sylvania 12AT7WC)

• Well extended upper and mid range
• Crisp
• Layered
• Details, details, details
• Soundstage depth increase; lots of space between notes
• Bass kick is there, but subbass presence is significantly recessed

TungSol’s give the Sylvania a bit more kick back, but the low end is over-all fast, dynamic, hyper controlled. Not a bass-head combination, but doesn’t sound offensively anemic. Wouldn't be my first choice though.

(With Raytheon 12AT7WC)

• Very complimentary tube selection
• A light, heavenly 'sing-song' sound yet still somehow rich
• Agile. Both tubes sets are quite dynamic, so they boost each other nicely.
• Extension; both tube sets have a touch of extension on the mid/upper mid range.
• Romance; a slower decay at the mid/upper mid range keeps this tube set from sounding overly clinical or “solid state”.

Potentially end-game tube combination for this amp

(With Telefunken 12AX7)

• Lots of space between notes
• Still has a lot of detail
• Punch from the telefunken is very welcome, produces a dynamic and balanced combo
• Nice bass
• Takes the holography from the telefunken and merges it with the detail retrieval of the tungsol.
• Incredible combination.

Overall a great combo. Very much similar tone to the factory sound of the HP8 but risen to a new level, and with attitude.

Sylvania 7N7 rebased to 6SN7GT “Bad Boy” Chrome Domes​

(With Sylvania tube 12AT7WC)

• Detailed & crystalline. Amazing upper range
• Faster roll off than the Tung-Sols
• Nice bass kick
• Subbass feels a tad veiled, & thin; doesn’t sound bad, but leaves you wanting in the lower register.
• Wonderful textured mid range however...
• Airier lower mid range than the Tungsols

Overall a smoother, dark-of-neutral tone with nice air and texture. Again, would not be my first choice though...

(With Raytheon 12AT7WC)

• A more balanced presentation
• Subbass kick
• Impact and note weight
• Mildly mid-forward

Overall a very pleasant, balanced combination. A close 2nd to the next one...

(With Telefunken 12AX7)

• Warm with lots of air
• Full bodied & splashy
• Crazy holography
• Mind-blowing

Story time... I was previously listening on the low gain amp option on the HP8 as my previous review noted I strongly disliked the other gain options. When I first listened to this combination, I didn't like it much. It sounded veiled and...mushy. Something prompted me to see what happens if I increase the gain because I thought "there's no way that's what these tubes sound like. I put a lot of research into these tubes...these should be great". Well, I turned the knob and then.... the clouds parted and the gods spoke to me through the voices of my ancestors and I bore witness to a sound unlike anything I have heard before. I then took a 2nd day to re-review everything I had heard on higher gain. The other tubes did not change much.

Comparing the final tube roll of both the HA-3A and the HP8 SE​

I ended up with a sound I loved respectively from both amps. Both amps are nowhere near their top potential in their factory form, though I would say it's my experience having now experimented on both it is easier, and much cheaper to raise up the HA-3A than the HP8, but the HP8 with good tubes is on a level I do not think the HA-3A can match. Close? Yes, but match? I don't think so. I also think the HA-3A's sound signature changes far more readily and quickly than the HP8. The HP8's sound signature is heavily reliant on the single 12AX7 tube. I tried leaving the factory David Shaw CV181's in, and the sound was still much improved; the DS 181's are well chosen, clean, revealing, transparent and articulate tubes. On the HA-3 I get the impression it would be fine to seek 12AU7's that are crisp, clean and leave it at that. The 6v6's are more than capable of producing a pleasing shift in sound if a user wanted to be conservative with their money. It was VERY expensive to bring up the sound of the HP8 in comparison.

Next I will try some different 12AX7's in the HP8 and see what happens. I have a hunch the reason the AT7's both sounded on the thin side was because the amp really was designed for an AX7 to be driving it.

Thank you very much for this kind of posts (and subsequent responses). This information is very useful, at least for someone like me who hasn't gotten into tubes yet.

From what I've read, it seems that not all good tube amps are easy for tube rolling (lack of availability of good alternatives, very high price, etc.). So, I think this is an important point to analyze before purchasing a tube amp (aside from the sound and synergy with your stuff, of course). But finding information on tubes to roll/alternatives/sound impressions, etc. for a specific tube amp is not an easy task. The information is there, but you have to dig a lot (an even take notes)… And reviewers usually don't go into this topic in depth. So, these types of posts help a lot

 

[Pharmaboy]

Someone who knows a lot about tubes (audio in general) is @Monsterzero. He advises people interested in a tubed component to research the availability & cost of NOS tubes for it. That way they don't get the too-late surprise that NOS tubes are prohibitively expensive.

It's terrific advice. Had I known about it, I may have thought twice about getting this gently used HP8. The cost of top NOS 6NS7 power tubes have skyrocketed over the years. Matched pairs of 6NS7s people praise the most sell for nearly as much as I paid for the amp itself. Luckily, I found a middle ground of solid, very good sounding tubes that are (at least for me) sanely priced and relatively affordable.

On the other hand, 12AT7s, unlike 12AX7s, have generally not skyrocketed nearly as much in price. Quite a few really excellent 12AT7s are available for non-silly money, still.

 

[jonathan c]

On those ‘work from home’ days, it is this

when ZMFs (Atrium LTD Cocobolo, above) are called to active duty. In later evening, this

takes over.

 

[jonathan c]

It’s the HeadFi Discovery channel afternoon programming. No snickering! This is a great combination!

[The Grado RA-1 ‘silent’ DC power from twin 9-volt batteries plays directly to Atrium’s strengths in dynamics, layering, and soundstage.]

 

[iamoneagain]

It’s the HeadFi Discovery channel afternoon programming. No snickering! This is a great combination! [The Grado RA-1 ‘silent’ DC power from twin 9-volt batteries plays directly to Atrium’s strengths in dynamics, layering, and soundstage.]

Wow I haven’t seen one of those in years. I used to own one. But then you realize it’s like $15 in electronics. The wood probably worth more than the electronics. Don’t they sell for over $300?

 

[jonathan c]

Wow I haven’t seen one of those in years. I used to own one. But then you realize it’s like $15 in electronics. The wood probably worth more than the electronics. Don’t they sell for over $300?

When the RA-1 was introduced in 2005, the battery-powered version sold for $350. The AC-powered version, with external power supply, sold for $425. I recently purchased both unopened & at original price. Wonderfully detailed, slightly sweet sound with ‘oomph’!