[RobertSM]

Well I've joined the club here with this Icon Audio headphone amp. I found a lightly used standard model from a retired man who is really downsizing his system after a life long love affair with audio.

After reading over the thread, I went ahead and brought a set of Mundorf Supreme Mcaps, silver/oil caps to upgrade. I have the amp at a respected amp repair shop having the caps being soldered in and having the amp tech giving it a good look over to see if it needs anymore love.

I'll deal with the tubes and what I've bought when I get this back.

Might be a couple of weeks before it gets on the bench and gets returned to me. Looking forward to sharing my thoughts.

Big thank you to those that have shared over the years. Your recommendations were noted and made it easy for someone like me to come in and learn from what's worked for others in years past.

 

[Nik74]

I went ahead and brought a set of Mundorf Supreme Mcaps, silver/oil caps to upgrade.

Great idea to first upgrade the capacitors as the difference they make in sq is substantial, they elevate this amp to the next level imho.
Do you remember the characteristics of the caps you ordered? Asking this because when I ordered mine , the values that Icon Audio provided were different to the ones discussed here and did perplex the engineer that undertook their fitting
In any case, looking forward to your impressions
N

 

[RobertSM]

@Nik74, I ordered the 0.33uF 1000Vdc caps. Hoping these will do the trick.

Just curious, did you upgrade the caps in your unit? If so do you mind sharing the brand, make and model of the caps. Also the values. Thanks.

 

[Nik74]

@RobertSM I did upgrade the capacitors a couple of months after buying the amplifier so can wholeheartedly say that the upgrade is a game changer for this amp. Like many people have already mentioned the stock caps are a bottleneck - so is the stock driver tube but that’s a whole other story.

I emailed Icon Audio and ordered the capacitors that they recommend directly from them . Those were Jensen copper foil paper in oil caps and the values were 0.1uf 630V , quite different to yours as I imagined ...I know nothing about the technicalities but my engineer found the values bizarre so got in touch with them to double check that these were indeed the right ones. Icon confirmed they were and offered an explanation that I don’t remember - again I lack the technical familiarity so didn’t care as long as it was right -.
I hope this is helpful but in any case I strongly suggest that you email or call them , they are very responsive and friendly
N

 

[RobertSM]

@Nik74, thank you. I'll email then straight away. Better to be sure.

 

[RobertSM]

@Nik74, emailed and already received a reply from Icon. You are right, the correct value is .1uF. I may use a capacitor rated 1000Vdc but was told to absolutely use the value of .1uf.

So, now I've ordered the correct caps. A bit of a bummer that I ordered the wrong caps. But I'll hold on to them, maybe I can use them in another project.

Again, thanks for the heads up.

 

[Nik74]

I have found this forum a source of great help and advice so it’s a pleasure to be able to help too
Looking forward to your impressions

Just make sure to get rid off the stock 12AX7 and find a nice Mullard mc1 or gold lion 12AX7 or even a Tungsram ECC83

 

[RobertSM]

Ok, got the correct capacitors soldered in. Stuck with the Mundorf Mcap supreme silver oil. Presently, burning in a pair of the new Sophia electric 6sn7 blue glass tubes and a 12ax7 also from Sophia.

I'm about 25 hours into the caps & tubes burn-in. Very much impressed with what I hear so far. Great detail and air to the sound signature. I know the term gets used alot, but I find this Icon Audio HP amp to be very musical. Also, I'm impressed with how black the amp is. Totally silent. Like, I hear zero distortion. In regards to power, this solidly built, hefty little amp has plenty of power. No issues at all driving my Sennheiser HD-6XX headphones with authority. Also, I did read a few prior comments regarding transformer noise/hum. I'm thankful that my unit is totally quite.

More to come as I get used to the amp and post caps and tubes burn-in. But this is really turning out to be a great amp.

 

[Nik74]

That is great to hear !
I m curious about your tube choices, I ve read about the Sophia 300B but didn’t know they also did 6SN7 and 12AX7, will do some research.
I m guessing your HP8 will need another 80 hours before it shows its true character

 

[RobertSM]

@Nik74

These are the newer design for Sophia. Apparently the original clear glass 6sn7 tubes had some problems. The blue glass tubes represent Sophia addressing those concerns.

Here is a photo. They do look a bit different...the blue glass and all.

 

[Nik74]

Wow they so much bigger than my electroharmonix !
I love the blue colour

 

[RobertSM]

The folks at Sophia electric say these use a 'coke bottle' shape. The tubes are priced by grade; A,B & C- grade. I sprung for a matched pair of the grade A. I'll share as they work through the burn-in period.

 

[hood177]

Hi all,
what about modding?
This is my ICON AUDIO HP8 MK2 Russian Bear Edition....

All that installed is seen in the photo:
- New ceramic vacuum tube sockets - it all started with the need to replace them

- new large aluminum plate
- top-level volume control TKD Ko-on 2CP-2511 50K
- Jupiter HT Beeswax Paper Foil Cryo interstage capacitors with bee-wax impregnated paper dielectric
- Capacitors of increased capacity in the power supply circuits Vishay and Cornell Dubilier SLP
- capacitors of increased capacity in cathode circuits Elna Cerafine
- 2W TKD Correctohm Metal Film and Kiwame resistors, Jantzen metal-ceramic
- diode bridges with ultra-fast diodes Vishay BYV26E-TAP and ON Semiconductor MUR420RLG
- CMC-803-F Gold plated RCA connectors

Soldering with WBT-0800 4% silver solder.

ICON AUDIO HP8 MKII Russian Bear Edition
SIEMENS ECC83 + Philips ECG JAN 6SN7WGTA (6Н8С)

ICON AUDIO HP8 MKII Russian Bear Edition

 

[RobertSM]

@hood177, looks amazing. I do have a couple of questions.

1. Looks like you removed the copper plate from the top and added a plate of metal that now totally covers the amp. What material did you choose?

2. How do you like the upgraded coupling/interstate capacitors? You choose a Juniper cap. I went with a Mundorf silver in oil. Wondering on the effect.

3. What tubes are you currently using? I moved away from the Sophia tubes shown in my last picture. I'm currently running, Siemens Halske 12AX7 produced in 1968. I was using a Mazda France 12AX7 from the mid 1960's which has a beautiful top-end sparkle and air but didnt give me the extremely wide bandwidth that the Siemens gave me. I'm also very happy with my Sylvania GTA 6SN7, these are the chrome dome tubes.

Either way, good work in the mods. Please share on how it's all working out for you.

 

[hood177]

Hi RobertSM,
thank you for rating.
I have already modified it twice.
1. Upper plate - anodized aluminum. Original plate - anodized aluminum too, not copper.
2. Jupiter HT caps - they are superior. I tested different and I like Jupiter more than others.
3. I have many different NOS 12AX7 and 6SN7 tubes and new Psvane Treasure 12AX7 LS Special Edition + Psvane CV181-TII ‘grey bottle’.
SIEMENS ECC83 + Philips ECG JAN 6SN7WGTA on the photo.