[Gr3g277]

So after 5 days I now switched the first time from the KT 88 to the EL34

Btw is tube burn in a thing?
And if so how long does it usually take to sound their best?

Hello ,

In my experience yes , tube burn in is really a thing, especially the GL kt88 take at least 50 h to settle in
The EH EL34 tube should sound good after 10h or so, but for me even after that time i didn't like them that much...

Tube rolling is a must with this one !

If you want to go that route, the small preamp tube have the most effect, look for mullard reissues, gold lions, NOS tubes like sylvania 6189, or RCA 5814A are really good as well, New production psvanes or TJ fullmusic are really good as well

For power tubes, don't look for NOS tubes, they are too expensive IMO. I go to a german based site called "tube amp doctor" they have a lot good stuff, and do a careful selection.

I have some psvanes on delivery, I'll report on them when they arrive.

BTW which headphones do you use with your HA-6A ?

 

[ThanatosVI]

Hello ,

In my experience yes , tube burn in is really a thing, especially the GL kt88 take at least 50 h to settle in
The EH EL34 tube should sound good after 10h or so, but for me even after that time i didn't like them that much...

Tube rolling is a must with this one !

If you want to go that route, the small preamp tube have the most effect, look for mullard reissues, gold lions, NOS tubes like sylvania 6189, or RCA 5814A are really good as well, New production psvanes or TJ fullmusic are really good as well

For power tubes, don't look for NOS tubes, they are too expensive IMO. I go to a german based site called "tube amp doctor" they have a lot good stuff, and do a careful selection.

I have some psvanes on delivery, I'll report on them when they arrive.

BTW which headphones do you use with your HA-6A ?

Thx for the advice.

I use my Meze Empyrean with them and the pairing is amazing.

I love the GL KT88 so far, the EL34 smooths out the bass too much in many occassions (it still sounds amazing but not as good as with the KT88).
For certain music I even prefer the EL34, but since I listen to a Broad spectrum of genres, the KT88 fits better at the moment.

Where can I read up on the sound character of the pre amp tubes?
I won't tube roll much and only to stuff that is readily available, but being informed doesn't hurt

 

[Gr3g277]

Thx for the advice.

I use my Meze Empyrean with them and the pairing is amazing.

I love the GL KT88 so far, the EL34 smooths out the bass too much in many occassions (it still sounds amazing but not as good as with the KT88).
For certain music I even prefer the EL34, but since I listen to a Broad spectrum of genres, the KT88 fits better at the moment.

Where can I read up on the sound character of the pre amp tubes?
I won't tube roll much and only to stuff that is readily available, but being informed doesn't hurt

here is a good start on NOS 12au7 type tubes.

https://audiofool.reviews/tube-rolling-the-xduoo-ta-01b-ta-10-and-ta-20-12au7-amps/

I bet the empy's sounds good on this amp !
Do you notice any background hiss with them? what is the sensitivity rating for them ?

 

[Articnoise]

So after 5 days I now switched the first time from the KT 88 to the EL34

Btw is tube burn in a thing?
And if so how long does it usually take to sound their best?

Yes tubes sounds better after 50-100 hours.

 

[ThanatosVI]

here is a good start on NOS 12au7 type tubes.

https://audiofool.reviews/tube-rolling-the-xduoo-ta-01b-ta-10-and-ta-20-12au7-amps/

I bet the empy's sounds good on this amp !
Do you notice any background hiss with them? what is the sensitivity rating for them ?

They sound amazing!

They have 32 ohm impedance with
100db@1mw/1kHz

The hiss is unfortunately there. It gets louder when turning the impedance switch to medium or high (it sounds best/more controlled on low to my ears anyways so not a big deal) also more noteable in ultralinear Mode than in triode.
It does not increase when turning the volume knob.

During music it is not noticeable, however when watching movies or anything at low volumes it is.
It is very low in volume but it is undeniably there.

I don't have anything to "clean" my power, maybe it is related to that, or to the tubes. I didn't notice any humm difference between EL34 and KT88 .

 

[Fatdoi]

like to ask, when the unit is switched on and you brush your finger on the case, do you feel static electricity?

 

[ThanatosVI]

like to ask, when the unit is switched on and you brush your finger on the case, do you feel static electricity?

No I don't

 

[Gr3g277]

No I don't

me neither, if you do, check your grounding

 

[Andykong]

They sound amazing!

They have 32 ohm impedance with
100db@1mw/1kHz

The hiss is unfortunately there. It gets louder when turning the impedance switch to medium or high (it sounds best/more controlled on low to my ears anyways so not a big deal) also more noteable in ultralinear Mode than in triode.
It does not increase when turning the volume knob.

During music it is not noticeable, however when watching movies or anything at low volumes it is.
It is very low in volume but it is undeniably there.

I don't have anything to "clean" my power, maybe it is related to that, or to the tubes. I didn't notice any humm difference between EL34 and KT88 .

Noise is directly related to power rating, the higher the power rating, the higher the noise. HA-6A offers a very wide range of output power to make it flexibility to our users when they can match with different headphones. To put this into context, with the same set of power tube the lowest output power setting is Triode mode + Low Impedance + Single-ended output (6.35mm), and the highest output power setting is Ultralinear mode + High Impedance + Balanced (XLR4 or 4.4mm). Roughly speaking, the later (UL+H+BAL) can be 7 higher than the first (TR+L+SE) setting. That also explained why you hear more noise when you switch to a high impedance setting with a low impedance headphone.

The table belows convert the power rating figures into Vrms so that we can compare them across different loading.

To summarize, when using KT88, at Low impedance setting, Single-end delivers 7.16Vrms, Balanced delivers 8.76Vrms, but when you switch to High impedance setting, Balanced delivers 51.96Vrms, that is 7.26x of SE (low) or 5.93x of BAL (low).

 

[ThanatosVI]

Noise is directly related to power rating, the higher the power rating, the higher the noise. HA-6A offers a very wide range of output power to make it flexibility to our users when they can match with different headphones. To put this into context, with the same set of power tube the lowest output power setting is Triode mode + Low Impedance + Single-ended output (6.35mm), and the highest output power setting is Ultralinear mode + High Impedance + Balanced (XLR4 or 4.4mm). Roughly speaking, the later (UL+H+BAL) can be 7 higher than the first (TR+L+SE) setting. That also explained why you hear more noise when you switch to a high impedance setting with a low impedance headphone.

The table belows convert the power rating figures into Vrms so that we can compare them across different loading.

To summarize, when using KT88, at Low impedance setting, Single-end delivers 7.16Vrms, Balanced delivers 8.76Vrms, but when you switch to High impedance setting, Balanced delivers 51.96Vrms, that is 7.26x of SE (low) or 5.93x of BAL (low).

Thx for that technical explanation.

Regarding triode/ultralinear Mode switch, the msnual claims that it remembers the last used state, however mine always starts in triode mode.

Is my device faulty or is the manual wrong?

 

[ThanatosVI]

Last time I already posted about the humm, so there isn't anything more to add. This is also the only negative point I could find about this amp.

So time for some sound impressions:

Background: I came from a Setup of
Android UUAP bit perfect -> Oppo Sonica -> Schiit Loki -> Meier Audio Corda Classic -> Norne Skraug cable -> Meze Empyrean( The corda classic is a mid fi Solid State amp, comparable to a Topping A90 or Schiit Jotunheim. It has a very neutral tone)

My current setup replaced the Corda Classic with the HA-6A.
I never owned a tube amp, nor an amp in that price range before.

Right from the get go (with KT88 in Triode mode) I noticed extremely good instrument separation, "tube magic" in the mids, guitars and vocals never sounded that addicting. Also bass guitars never sounded even remotely as good as here. The Staging has great depth (not witdh, which is still good). The amp has amazing detail retrieval and I noticed things I never heard before. This was the most surprising fact for me, considering that the corda classic is no slouch in it's league. Overall it has a very relaxing sound signature much like the Empyrean character. You simply sink into the music and forget the world around you. However it always stays engaging never gets boring or too smooth..
When switching to Ultralinear mode, the subbass becomes more noteable, very tight and textured, the extension is amazing. Also the highs receive quite some sparkle energy. This has overall solid state character but with just the right amount of tube magic. For me personally this is better than pure solid state.
I also really love the fact that the button is easily accessible on the front. It's not a "choose your favourite and done" I switch very frequently depending on the song.
Generally genres with string instruments and focus on vocals -> Triode mode
Modern electronic music (hardstyle, dubstep) -> Ultra linear

After a few days I switched to the EL 34 tubes.
In Triode mode they offered even more tube magic. Guitars and vocals sound magical, but for my taste it smooths out the edges too much. I really love my subbass which takes a hit. They have their upside but unless I have a phase when I listen only to a certain genre, the KT 88 are superior.
The KT 88 also offer better separation.

I think that this amp is just perfect for me. I use the Triode/Ultralinear feature A LOT, the amp is so versatile and gives me the feeling to always get the best sound possible for whatever I listen to.
Due to this feature I think that I might prefer this amp even to the "bigger brother" Ha-300, which might sound "too smooth" for modern electronic music.

Maybe I start some tube rolling around christmas.
Starting with the preamp tubes, while keeping the Generalex Gold Lion KT88.
Any recommendations on readily available (so likely current production) tubes?

Can someone describe the sound of gold lions, mullards, psvanes? (all the "cheap" reissues)
I don't plan to roll much, since I am actually really happy with the standard KT 88s, but preamp tubes are said to have the most impact anyways.

Which tubes give the best subbass (texture and quantity - importance in that order). Or give great subbass while retaining that mid magic that the standard Electro Harmonix 12au7 have?

 

[GU1DO]

Hi all,

I just want to give a closer for my problem ,, few days ago i got refunded after cayin received there packge , hopefully i will revisit this amp after the hiss issue get sorted and i see more positive feedback, also i want to thank Mr.John who was the contact from Cayin, he was very patient with me.

Best regards.

 

[kimdeug]

Hi all,

I just want to give a closer for my problem ,, few days ago i got refunded after cayin received there packge , hopefully i will revisit this amp after the hiss issue get sorted and i see more positive feedback, also i want to thank Mr.John who was the contact from Cayin, he was very patient with me.

Best regards.

Good to know that Cayin has provided refund. In my case, the local repair service has ordered the new board and will replace it. But I have very strong suspicious that it will not fix the problem. next will be refund. 3 months repair waiting is quite hard. I do not understand why Cayin until now did not recall the unit and done proper investigation. Instead of that they prefer the local repair shops all around the world to fix their problems. If it is a faulty parts it can help, but if it is a poor circuit design the local shop will not be able to fix it. Now Cayin try to convince me it is a a faulty parts, but from my radio experience it looks like poor circuit design. I have asked to measure on oscilloscope how clean DC power comes to driver tube 12AU7 (from my point the problem around this area), Also I am thinking to made bypass, take the driver stage from another OLT amp and connect to the Cayin amplification part (KT88) and vise versa to find where is the problem. Regards, Kim

 

[Gr3g277]

Good to know that Cayin has provided refund. In my case, the local repair service has ordered the new board and will replace it. But I have very strong suspicious that it will not fix the problem. next will be refund. 3 months repair waiting is quite hard. I do not understand why Cayin until now did not recall the unit and done proper investigation. Instead of that they prefer the local repair shops all around the world to fix their problems. If it is a faulty parts it can help, but if it is a poor circuit design the local shop will not be able to fix it. Now Cayin try to convince me it is a a faulty parts, but from my radio experience it looks like poor circuit design. I have asked to measure on oscilloscope how clean DC power comes to driver tube 12AU7 (from my point the problem around this area), Also I am thinking to made bypass, take the driver stage from another OLT amp and connect to the Cayin amplification part (KT88) and vise versa to find where is the problem. Regards, Kim

Do you know what parts needed to be changed , by your local shop ?

 

[ThanatosVI]

So the wife bought me a pair of Electro harmonix 12au7 gold, tube rolling starts earlier than expected.

How long do these usually take to burn in?