KT 88 Driver Stage Alternatives.

[AP@1992]

Thanks for sharing that video, that cayin is grogeous

This Cayin, along with many of their new radical tubes amp posted in their site is crazy.

 

[AP@1992]

It’s the onus of the designer / maker of the amp to clearly specify tubes to be used. 6SL7 is high gain and low current tube and 6SN7 is opposite. So the real sonic impact will depend on the biasing of the amp. I would still urge to try 6CA7 tubes in place of KTs or 34. And driver stage tube as stated by the amp maker.

My own favorite driver stage tubes are 6SN7 (Russian) and 6N2P. I find 6CA7 to be more pleasant sounding than EL34 in every way. Details and instrument separation was staggering.

I am trying to lay my hands on some 6CA7 and will report back my impressions on the same.

 

[AP@1992]

Update on the tube rolling with Cayin AT88-mk2

System 1: Kt88 Sovtek + Stock 6ns7 and 6sl7
Sound had slam and punch. Bass was terrific, so was the treble. Overall the sound was detailed, clear and precise with great separation of instruments. The midrange, particularly voices were so crystal clear and tangible that it felt like a centre channel is installed. However, the voices sound dry, without a lot of texture and kind of tiny and not very intimate. There was total lack of warmth with the voices as well. With certain tracks voices had a harshness and sort of sibilant.

System 2: Kt88 Sovtek + Russian NOS 6H9C + 6H8C
All the pro’s of system 1 remained. However the midrange, particularly the voices had bit more warmth. Smoothness also increased. The voices sounded little bigger and lil more forward and were slightly more intimate.

System 3: Kt88 Sovtek + Russian NOS 6H9C + PS Vane UK 6NS7

All the pros of system 2 remained same. Additionally midrange warmth increased even more. Voices now had a nice texture to them and they no longer sounded tiny. They sounded more open, big and nicely forward and intimate.

At this point, I realised I have matched Quad of PS vane El34C lying unused, which came as stock with my Boyuurange.

System 4 PS EL34C+ Russian NOS 6H9C + PS Vane UK 6NS7

Sounded very different. That warm, smooth tone of EL34 made its presence felt. Voices had a lot of texture, Sounded big, warm, smooth and nicely forward. Bass articulation, separation of instrument, treble extension, clarity, pace, punch small were all less than System 3, but with rights songs this rich, warm, and lush tone is really addictive. Midrange/voices clarity was also great and there was nothing to be desired, but this was not at the same level as system no. 3 which was in some other level.

To put it in a “philosophically audiophile” lingo, System 3 pleases the mind whereas system 4 pleases the heart.

Also, Cayin A88T Mk2 , in general, and irrespective of the kinds of tubes I put, did a great job with bass, mid-range clarity (both voices and instruments) and treble performance. I am really surprised at the quality of these amps. Very well made amp too. The current iteration i.e. CS-88A is exorbitantly priced though.

Lastly, amazed at how tube rolling can meaningfully effect and get you the sound you prefer.

Atlast I tried my Mullards NOS EL34. These are obscenely prized and I had managed to get these courtesy some jugaad.


System 5. Mullards EL34 NOS + PS Vane UK6ns7 and Russian NOS 6H9C.

Same warm and textured tone of system no.4 remained. Voices and instruments pops out and this one sounds properly holographic. The bass, dynamics, pace, attack, clarity, seperation of instruments etc etc everything was more or less same in relation to system 4. Bass may be a Lil less punchy.

Since the voices are very palpable and oozes out and floats around, sense of clean sound and clarity does suffer a bit. But voices are wonderfully textured and smooth.

This one sounds more closer to a general description of a tube sound. Mellow, liquid mid-range and romantic sounding.

This sound is however limited by the choice of songs it plays well.

 

[AP@1992]

@yogibear @Yelamanchili manohar @coaltrain

I was informed by users of this specific amp that the low gain and higher volt 6NS7 in charge of the driver stage impact the sound considerably.
I was further advised to use a livelier (and more having resolution) 6NS7 (preferably one from Tungsol) if I wish to pair the Mullards NOS EL 34 with it. Since these version of Mullards although sounding big, lush and holographic, lacks a bit of resolution, is slow and sounds darker.

I was also told that the PS Vane UK 6NS7 is made to replicate old NOS tubes of European mades, and have a nice neutral to warm tone and open/big and forward sound stage with nice mids; however doesn't compare well to Russian made tubes in so far as clarity, sense of air, separation and resolution is concerned.

So I did that:

System 6- Mullards EL34 NOS + "Tungsol 6NS7 GTB" and Russian NOS 6H9C.

1. Similar to system 5, midrange oozes out. Sound stage depth and width are huge like system 5 i.e. properly holographic. Voices literally float and are very intimate and forward.
2. Voices and instruments have great texture to them, are "adequately warm" but they now sounded less darker and with better resolution.There was a notable increase from System 5 in terms of clarity, air, focus, dynamics, pace, attack and separation of instruments. Bass thump has returned although not punchy, incisive or articulate like System 3 (KT88 based)
3. This sound is suitable for most kind of music i like. It can handle a large variety of tracks really well. Jazz, blues, Ghazal, unplugged, countryside, pop etc etc.
4. However, tracks with a lot of drama, orchestral pieces or where too much is happening, System 3 (KT 88 based) will be ideal. But for everything else, System 6 is a right mixture of sounding warm, with adequate detail and clarity, all whilst sporting a holographic sound stage.
5. I also observed that songs which are not recorded well or doesn't have inherent depth in the recording, with this level of huge sound stage and "oozing out midrange", can sound little artificial. But thats only for a limited amount of songs.
6. Lastly, System 6 whilst sounding sufficiently warm, smooth and textured, doesn't sound liquid smooth like System 5. That is obviously because of the added sense of clarity, separation and focus, which IMO is nice sacrifice and makes it suitable for a larger variety of songs.

 

[coaltrain]

@AP@1992
You’re not just tube rolling, you’re rolling and rocking!
Sounds like you’re getting pretty close to your ideal sound; a space that we’d all like to occupy

 

[AP@1992]

@AP@1992
You’re not just tube rolling, you’re rolling and rocking!
Sounds like you’re getting pretty close to your ideal sound; a space that we’d all like to occupy

That space sadly doesn't exist.

 

[Yelamanchili manohar]

@yogibear @Yelamanchili manohar @coaltrain

I was informed by users of this specific amp that the low gain and higher volt 6NS7 in charge of the driver stage impact the sound considerably.
I was further advised to use a livelier (and more having resolution) 6NS7 (preferably one from Tungsol) if I wish to pair the Mullards NOS EL 34 with it. Since these version of Mullards although sounding big, lush and holographic, lacks a bit of resolution, is slow and sounds darker.

I was also told that the PS Vane UK 6NS7 is made to replicate old NOS tubes of European mades, and have a nice neutral to warm tone and open/big and forward sound stage with nice mids; however doesn't compare well to Russian made tubes in so far as clarity, sense of air, separation and resolution is concerned.

So I did that:

System 6- Mullards EL34 NOS + "Tungsol 6NS7 GTB" and Russian NOS 6H9C.

1. Similar to system 5, midrange oozes out. Sound stage depth and width are huge like system 5 i.e. properly holographic. Voices literally float and are very intimate and forward.
2. Voices and instruments have great texture to them, are "adequately warm" but they now sounded less darker and with better resolution.There was a notable increase from System 5 in terms of clarity, air, focus, dynamics, pace, attack and separation of instruments. Bass thump has returned although not punchy, incisive or articulate like System 3 (KT88 based)
3. This sound is suitable for most kind of music i like. It can handle a large variety of tracks really well. Jazz, blues, Ghazal, unplugged, countryside, pop etc etc.
4. However, tracks with a lot of drama, orchestral pieces or where too much is happening, System 3 (KT 88 based) will be ideal. But for everything else, System 6 is a right mixture of sounding warm, with adequate detail and clarity, all whilst sporting a holographic sound stage.
5. I also observed that songs which are not recorded well or doesn't have inherent depth in the recording, with this level of huge sound stage and "oozing out midrange", can sound little artificial. But thats only for a limited amount of songs.
6. Lastly, System 6 whilst sounding sufficiently warm, smooth and textured, doesn't sound liquid smooth like System 5. That is obviously because of the added sense of clarity, separation and focus, which IMO is nice sacrifice and makes it suitable for a larger variety of songs.

Thanks a ton for posting your detailed observations with various tubes. This will be a handy guide for me when I next have to replace my tubes. All are presently brand new, after a routine service to tame some frequent bias drift in the amps. So I hope Iam good for the next 5 years, considering my sparse usage. It was just plain coincidence that I was previously using the EH EL34's, and when replacement time came, I could only find the JJ new issues on amazon. So went for them. I think my input tubes are Gold lion 12AX7's. Luckily the combination just fell in place, with a rich presentation, not sacrificing dynamics, detail and bass. I could'nt be happier, and have absolutely no inclination to try anything else.

 

[AP@1992]

Thanks a ton for posting your detailed observations with various tubes. This will be a handy guide for me when I next have to replace my tubes. All are presently brand new, after a routine service to tame some frequent bias drift in the amps. So I hope Iam good for the next 5 years, considering my sparse usage. It was just plain coincidence that I was previously using the EH EL34's, and when replacement time came, I could only find the JJ new issues on amazon. So went for them. I think my input tubes are Gold lion 12AX7's. Luckily the combination just fell in place, with a rich presentation, not sacrificing dynamics, detail and bass. I could'nt be happier, and have absolutely no inclination to try anything else.

My recent experiment with tube rolling made me realise that tube synergy is actually quite a thing.

 

[Hari Iyer]

My recent experiment with tube rolling made me realise that tube synergy is actually quite a thing.

My experience with tube rolling have not been very exiting with positive outcomes. I have rolled 12au7 Shugaug with Tunsol and Shuguag 300B with Psvane mesh plate. After the initial thrill they both sounded same to my ears.

 

[AP@1992]

My experience with tube rolling have not been very exiting with positive outcomes. I have rolled 12au7 Shugaug with Tunsol and Shuguag 300B with Psvane mesh plate. After the initial thrill they both sounded same to my ears.

I suppose that initial thrill is what drives us. Like everything else in life, passage of time, does even out everything. Hifi is no different.

 

[yogibear]

I suppose that initial thrill is what drives us. Like everything else in life, passage of time, does even out everything. Hifi is no different.

Well said. Having reached the top tier of audio reproduction mostly through DIY (partially including the DAC too), the thrill has simmered. And I now question my own bygone craziness….

 

[Hari Iyer]

Well said. Having reached the top tier of audio reproduction mostly through DIY (partially including the DAC too), the thrill has simmered. And I now question my own bygone craziness….

Does that mean after reaching the heights it's now time to retire?

 

[yogibear]

Does that mean after reaching the heights it's now time to retire?

Hari, a few speaker projects to be completed. Parts done, assembly and crossover parts to be taken up.

However a couple of tube amp designs are in the way including a huge 300B. Iron in hand, chassis is awaited.

 

[AP@1992]

Hari, a few speaker projects to be completed. Parts done, assembly and crossover parts to be taken up.

However a couple of tube amp designs are in the way including a huge 300B. Iron in hand, chassis is awaited.

@Hari Iyer

There is nothing called retirement in the pursuit of perfect sound.

As they say 'the top of one mountain is the bottom of another'

Also, DIY builders like you and @yogibear must never retire.

 

[sunilj]

Yes, it has manual biasing.

It will take in KT77 as it works at similar plate voltage as a EL 34 and generally a drop in replacment. Will try my EL34's and also report back.

Strangely, I haven't been able to get any information on the CV345. These tubes are old, cheap and drop in replacement for KT88

I've played with CV345 (12E1) and they are not a drop-in replacement for KT88. They both could be ~30w diss tubes but don't bias up the same . All my experiments are on the Tubelab SSE and the 12E1 can pull 67v on the cathode with a plate voltage of ~300/310.

The SSE is cathode bias, so, if you are going grid bias it could be different.

 

[AP@1992]

I've played with CV345 (12E1) and they are not a drop-in replacement for KT88. They both could be ~30w diss tubes but don't bias up the same . All my experiments are on the Tubelab SSE and the 12E1 can pull 67v on the cathode with a plate voltage of ~300/310.

The SSE is cathode bias, so, if you are going grid bias it could be different.

Thanks for the reply.

I dropped the idea of replacing KT 88 with 12E1. It's may involve damaging the amp or at the very less introduction unwarranted noise / hum, if not done right

 

[AP@1992]

@AP@1992
You’re not just tube rolling, you’re rolling and rocking!
Sounds like you’re getting pretty close to your ideal sound; a space that we’d all like to occupy

I have got hold of a extremely rare and sought after NOS Tungsol Made 6sl7GT (Smoked Glass). It was obscenely prized but got some jugaad.

I have installed it. Will report back my changes.

Driver 6sn7 tubes, really exhibited not so subtle sonic changes with every tube change. Hope the same is true for 6sl7.

 

[Yelamanchili manohar]

I have got hold of a extremely rare and sought after NOS Tungsol Made 6sl7GT (Smoked Glass). It was obscenely prized but got some jugaad.

I have installed it. Will report back my changes.

Driver 6sn7 tubes, really exhibited not so subtle sonic changes with every tube change. Hope the same is true for 6sl7.

Will fondly look forward to your well narrated and detailed listening impressions as usual. I enjoy reading them

 

[AP@1992]

Will fondly look forward to your well narrated and detailed listening impressions as usual. I enjoy reading them

Sure. Initial impressions are positive. But will give these serious looking black smoked glass some time. I want to understand the reason for their obscene prices. Is it only because they are the famed tubes from 40's used by American Army and are rare OR it is because they are good IN COMPARISON to others.

 

[yogibear]

Sure. Initial impressions are positive. But will give these serious looking black smoked glass some time. I want to understand the reason for their obscene prices. Is it only because they are the famed tubes from 40's used by American Army and are rare OR it is because they are good IN COMPARISON to others.

That black coating is a special paint made by only one company on the planet and it’s a heat sinking paint. It’s very expensive paint / coating.

Some tubes have it and they are all expensive as one of my favorite driver stage tube which is EF12, first seen in Klangfilm F2a amps.