KT 88 Driver Stage Alternatives.

[AP@1992]

Enamored by the Boyyurange EL 34 Tube amp (fitted with Mullards EL34, GZ34 rectifier and Russian 6HI), I was convinced that for the songs I prefer, this sounds best.

So I decided to let go of my Rega Elex Mark IV. Instead of a sale, I got an offer to exchange it with a Cayin A-88T MKii. I took the bite. That things looks gorgeous.

However the Cayin sounds very unlike the Boyyurange. Fitted with Sovtek KT88, Ps vane UK6sn7, Tugsol GTB 6sl7, it sounds clean, clear and precise. Unbelievable midrange clarity and base and treble extension. Demanding songs that needs drama and dynamics, it sounds great.

However, in comparison with my other tube amp, there is total lack of warmth and tonal richness.

This was partly remedied by swapping the input stage with Russian NOS 6ns7 and 6sl7.

I wanted to know, whether there exists a KT 88 tube which is on the warmer side of things.

How about Mullards (new production KT88) ? My go to tube dealer has also suggested a very rarely used CV345 (aka 12E1's) as a drop in replacement for KT 88? Any experience?

Cayin does come with a EL34 selector, however would want to retain the dynamics of KT88 and looking to get some bloom and warmth to go with it.

Recommendation and suggestion are really welcome.

 

[Hari Iyer]

Enamored by the Boyyurange EL 34 Tube amp (fitted with Mullards EL34, GZ34 rectifier and Russian 6HI), I was convinced that for the songs I prefer, this sounds best.

So I decided to let go of my Rega Elex Mark IV. Instead of a sale, I got an offer to exchange it with a Cayin A-88T MKii. I took the bite. That things looks gorgeous.

However the Cayin sounds very unlike the Boyyurange. Fitted with Sovtek KT88, Ps vane UK6sn7, Tugsol GTB 6sl7, it sounds clean, clear and precise. Unbelievable midrange clarity and base and treble extension. Demanding songs that needs drama and dynamics, it sounds great.

However, in comparison with my other tube amp, there is total lack of warmth and tonal richness.

This was partly remedied by swapping the input stage with Russian NOS 6ns7 and 6sl7.

I wanted to know, whether there exists a KT 88 tube which is on the warmer side of things.

How about Mullards (new production KT88) ? My go to tube dealer has also suggested a very rarely used CV345 (aka 12E1's) as a drop in replacement for KT 88? Any experience?

Cayin does come with a EL34 selector, however would want to retain the dynamics of KT88 and looking to get some bloom and warmth to go with it.

Recommendation and suggestion are really welcome.

Past 3.5 years, I am using KT-88 as my finals in my direct coupled SET amplifier. My driver tube is 6FQ7 and is a two stage design.

 

[AP@1992]

Past 3.5 years, I am using KT-88 as my finals in my direct coupled SET amplifier. My driver tube is 6FQ7 and is a two stage design.

KT 88 of which manufacturer ?

 

[Hari Iyer]

KT 88 of which manufacturer ?

EH

 

[Yelamanchili manohar]

Enamored by the Boyyurange EL 34 Tube amp (fitted with Mullards EL34, GZ34 rectifier and Russian 6HI), I was convinced that for the songs I prefer, this sounds best.

So I decided to let go of my Rega Elex Mark IV. Instead of a sale, I got an offer to exchange it with a Cayin A-88T MKii. I took the bite. That things looks gorgeous.

However the Cayin sounds very unlike the Boyyurange. Fitted with Sovtek KT88, Ps vane UK6sn7, Tugsol GTB 6sl7, it sounds clean, clear and precise. Unbelievable midrange clarity and base and treble extension. Demanding songs that needs drama and dynamics, it sounds great.

However, in comparison with my other tube amp, there is total lack of warmth and tonal richness.

This was partly remedied by swapping the input stage with Russian NOS 6ns7 and 6sl7.

I wanted to know, whether there exists a KT 88 tube which is on the warmer side of things.

How about Mullards (new production KT88) ? My go to tube dealer has also suggested a very rarely used CV345 (aka 12E1's) as a drop in replacement for KT 88? Any experience?

Cayin does come with a EL34 selector, however would want to retain the dynamics of KT88 and looking to get some bloom and warmth to go with it.

Recommendation and suggestion are really welcome.

Your findings echo my own impressions in going from a KT88 to EL34, both tube rolled in the same amp of course. I went from an electro harmonix KT88 to JJ EL34 that I found on amazon. And I much prefer the EL34 to the KT88 on most music. The KT88 sounded detailed, but with slam and speed like a Class A solid state amp. I did'nt want the hassle of changing tubes every 4 years when a SS amp could deliver the same sound on the cheap. The EL34 by comparison is more sweeter and liquid in the mids. Perhaps there is a little bloom in the bass too. I havent seen any let up in bass or treble extension.

I preferred ultra-linear with maximum negative feed back on the KT88's.
And I prefer triode mode with zero negative feed back on EL34's.
And I deliberately under bias the tubes by 10% to prolong tube life and not to stress the amps. So they dont run at their optimum voltages and dont sound at the very best of their potential, but I like the added distortion ( tubey goo a goo )

Even I found subtle changes swapping out the input / driver tubes. I think I changed from EH to Gold lions 12AH7 and found a slight uptick in transparency and a cleaner sound. But my mind might be making that up.

One tube guru once told me, that the valve has no sound of its own, but it is the circuit that we hear. So the same valve in different designs will sound very different .

Since the Cayin has the EL34 option, I would suggest to give that a try. Iam sure cayin has built in the option of voicing the amp for warmth when providing that EL34 VS KT88 selector switch and you maybe pleasantly surprised with the difference. All the best

 

[AP@1992]

Your findings echo my own impressions in going from a KT88 to EL34, both tube rolled in the same amp of course. I went from an electro harmonix KT88 to JJ EL34 that I found on amazon. And I much prefer the EL34 to the KT88 on most music. The KT88 sounded detailed, but with slam and speed like a Class A solid state amp. I did'nt want the hassle of changing tubes every 4 years when a SS amp could deliver the same sound on the cheap. The EL34 by comparison is more sweeter and liquid in the mids. Perhaps there is a little bloom in the bass too. I havent seen any let up in bass or treble extension.

I preferred ultra-linear with maximum negative feed back on the KT88's.
And I prefer triode mode with zero negative feed back on EL34's.
And I deliberately under bias the tubes by 10% to prolong tube life and not to stress the amps. So they dont run at their optimum voltages and dont sound at the very best of their potential, but I like the added distortion ( tubey goo a goo )

Even I found subtle changes swapping out the input / driver tubes. I think I changed from EH to Gold lions 12AH7 and found a slight uptick in transparency and a cleaner sound. But my mind might be making that up.

One tube guru once told me, that the valve has no sound of its own, but it is the circuit that we hear. So the same valve in different designs will sound very different .

Since the Cayin has the EL34 option, I would suggest to give that a try. Iam sure cayin has built in the option of voicing the amp for warmth when providing that EL34 VS KT88 selector switch and you maybe pleasantly surprised with the difference. All the best

Appreciate your response. I felt slight lacked of treble and bass extension, may be, cos I used EL34 in a different, much lower powered AMP. Rest, our findings and impression are mostly similar.

I am told that new production Mullard (now manuf through New Sensor) makes KT 88, which sounds lightly sweeter and warmer albeit slower. Also, the very old CV345 (the cap design) is also a replacement and sounds good.

I agree that tubes don't change sound as much we think they do but those subtle changes which play a huge role in the realm of 'pyschoaccoustics' that is the 'perceived sound'. That is what is addictive.

 

[Anshul_J]

As @Yelamanchili manohar mentioned above, change the power tubes to EL34, It will be more to your liking, overall a more musical tube. Also check if you could use KT77 tubes(usually a direct replacement for EL34), there are glowing reviews for Gold Lion KT77 tubes, supposed to be among the best new production tubes in the category.

 

[AP@1992]

As @Yelamanchili manohar mentioned above, change the power tubes to EL34, It will be more to your liking, overall a more musical tube. Also check if you could use KT77 tubes(usually a direct replacement for EL34), there are glowing reviews for Gold Lion KT77 tubes, supposed to be among the best new production tubes in the category.

Thanks for your response.

EL 34, I know is my last resort. I have those NOS Mullards which sounds wonderful. However, I wanted to understand if there were any KT 88 alternatives which could be a middle ground, retaining it's signature slam and drifting towards a more smoother and warmer tone.

 

[Anshul_J]

You can also try Tungsol 7581A, it is supposed to be sonically somewhere between KT88 and EL34. Search about them online.

 

[Yelamanchili manohar]

As @Yelamanchili manohar mentioned above, change the power tubes to EL34, It will be more to your liking, overall a more musical tube. Also check if you could use KT77 tubes(usually a direct replacement for EL34), there are glowing reviews for Gold Lion KT77 tubes, supposed to be among the best new production tubes in the category.

Even I would recommend the KT77, read that they are middle ground between EL 34 and KT88. But then the amp should be able to accommodate these tubes. Do you have the option of manual bias if you try something other than EL34 or KT88 on the Cayin.

Whether you ultimately settle with KT88 or EL34 will also depend on your speakers efficiency. My speakers are around 90db, so the EL34 in their triode mode putting out a measly 40 watt per channel is more than enough for me in my small room.

Moving up from the KT77 into KT88 or KT 120 or KT150 is mostly an increase in power keeping the same sound characteristics. So instead of trying different makes of KT88's, I would suggest to try the EL34's you already have at hand in the Cayin, and then take a call.

Iam adding @yogibear to the conversation, fondly hope he will chip in, in due time.

 

[AP@1992]

Even I would recommend the KT77, read that they are middle ground between EL 34 and KT88. But then the amp should be able to accommodate these tubes. Do you have the option of manual bias if you try something other than EL34 or KT88 on the Cayin.

Whether you ultimately settle with KT88 or EL34 will also depend on your speakers efficiency. My speakers are around 90db, so the EL34 in their triode mode putting out a measly 40 watt per channel is more than enough for me in my small room.

Moving up from the KT77 into KT88 or KT 120 or KT150 is mostly an increase in power keeping the same sound characteristics. So instead of trying different makes of KT88's, I would suggest to try the EL34's you already have at hand in the Cayin, and then take a call.

Iam adding @yogibear to the conversation, fondly hope he will chip in, in due time.

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

 

[yogibear]

I don’t like KTs…. I would try 6CA7 fat bottle or winged C by Sovtek or Svetlana and select EL34 option on the amp.

I am not a believer of big brands for miracle. Miracle happens from clever execution of the amp around a single tube in mind. I am very fine with RCA, GE, Sylvania brands.

 

[Hari Iyer]

After listening to EH KT88, it will be extremely difficult for me to consider any other final tube.

 

[AP@1992]

After listening to EH KT88, it will be extremely difficult for me to consider any other final tube.

I don’t like KTs…. I would try 6CA7 fat bottle or winged C by Sovtek or Svetlana and select EL34 option on the amp.

I am not a believer of big brands for miracle. Miracle happens from clever execution of the amp around a single tube in mind. I am very fine with RCA, GE, Sylvania brands.

Any experience with CV345

After listening to EH KT88, it will be extremely difficult for me to consider any other final tube.

I quite see why KT 88 is so loved. But its all a matter of taste, music genres and personal preferences.

 

[Hari Iyer]

Any experience with CV345

No

 

[yogibear]

Any experience with CV345

CV345 Beam power tube with top anode plate and same octal base as EL34 / KT88 but it’s not a pentode. I wouldn’t use it instead of any of those two.

Would also need an adapter to sit on EL34 octal base. It’s fine to do this as an experiment if plate / grid voltage and cathode biasing permits but quite detrimental in the long run. You can run into hum / distortion issues.

Played these games to my own fill….

 

[AP@1992]

CV345 Beam power tube with top anode plate and same octal base as EL34 / KT88 but it’s not a pentode. I wouldn’t use it instead of any of those two.

Would also need an adapter to sit on EL34 octal base. It’s fine to do this as an experiment if plate / grid voltage and cathode biasing permits but quite detrimental in the long run. You can run into hum / distortion issues.

Played these games to my own fill….

That's for this.

That's for this.

Thanks*

 

[coaltrain]

Hi @AP@1992
I have a Cayin CS 55A with the following tubes installed:
Psvane KT88C, NOS BEL 5814A and NOS BEL ECC83.
You can read my notes on each at the page linked here:

Blind Luck

Beautiful looking room there @coaltrain Enjoy your new setup :)

www.hifivision.com

I was informed by Cayin that the preamp tubes would have the biggest sonic impact, and they were right. Switching between various KT 88s was far more subtle.

Since you liked the EL34’s sound signature, I would second the KT77 and 6CA7 recommendations. And, as you also like the KT88, why not try the 6550 as well? You just might find one that gels well with the rest of your setup.

Also, as @yogibear correctly points out, the CV345 might cause problems. Below is a recommended tubes list from the CS 55A manual. No mention of the ‘345:

 

[AP@1992]

Hi @AP@1992
I have a Cayin CS 55A with the following tubes installed:
Psvane KT88C, NOS BEL 5814A and NOS BEL ECC83.
You can read my notes on each at the page linked here:

Blind Luck

Beautiful looking room there @coaltrain Enjoy your new setup :)

www.hifivision.com

I was informed by Cayin that the preamp tubes would have the biggest sonic impact, and they were right. Switching between various KT 88s was far more subtle.

Since you liked the EL34’s sound signature, I would second the KT77 and 6CA7 recommendations. And, as you also like the KT88, why not try the 6550 as well? You just might find one that gels well with the rest of your setup.

Also, as @yogibear correctly points out, the CV345 might cause problems. Below is a recommended tubes list from the CS 55A manual. No mention of the ‘345:

View attachment 82726

Thank you.

I did installed Russian NOS pre tube and I immediately noticed a change. Sound had a hint of warmth and voices had a bit more bloom.

I suspect that after burn it, they will get better.

Regarding EL34 or its substitutes, I will eventually install it at some point.

 

[IndianEars]

The KT88 tube has a punchy & incisive sound....

No brand of KT88 will mimic a 300B

If you are looking for a vastly more mellow sound, you will probably need yo change your amp to one that uses different output tubes... these will most probably be lower powered output tubes.

Within the KT88 sound signature boundary, I would recommend the 6550 Tube.

The 6550 is electrically Identical to the KT88, and is the USA's equivalent of the KT88.

The 6550 tube tames the bite of the KT88, leaving the same drive & punch.