[kinku]

Hi,
I am the proud owner of a Cayin A70-T(Manual biased)  . I bragged a little bit about some weak bass issues.Seems like a powertube issue than anything(they are 6 years old).I am wondering if y'all have experience with pre amp tubes for this Model. Currently running on RCA clear tops 12AU7 and Amperex bugleboy 12AX7.Soon will be changing the original power tubes to Tung Sol 6550. I do not want to lose the transperency and musicality of this amp with current config. But please share your experience,understanding after certain limits all those changes are basically how your ears are(and brain) tuned for.
Current config is extremely good for vocals ,violin ,instrumental and not at par with POP and hip hop(may be its the  excessive mids).

[ltr317]

Hi,
I am the proud owner of a Cayin A70-T(Manual biased)  . I bragged a little bit about some weak bass issues.Seems like a powertube issue than anything(they are 6 years old).I am wondering if y'all have experience with pre amp tubes for this Model. Currently running on RCA clear tops 12AU7 and Amperex bugleboy 12AX7.Soon will be changing the original power tubes to Tung Sol 6550. I do not want to lose the transperency and musicality of this amp with current config. But please share your experience,understanding after certain limits all those changes are basically how your ears are(and brain) tuned for.
Current config is extremely good for vocals ,violin ,instrumental and not at par with POP and hip hop(may be its the  excessive mids).

Changing the preamp tubes will change the tonal emphasis but not give more bass.  You need to change the output tubes for that purpose.

[kinku]

Thank you. Glad that I got your attention. Do you have any recommendations for power tubes? What I am looking for is a no coloration but warm equally balanced sound.Monitor audio RS6 is bright on the upper frequencies as you might already know.
Do I need to change all 4 powertubes at a time. I was thinking of changing one channel(one pair) to see the difference.

[FullRangeMan]

FWIW, 12AU7 and 12AX7 had many similar tubes:

12AU7(gain=20):  ECC82, ECC802S, 5963, 5814, 6189, 5814, 5963, 6189, 7316

12AX6(gain=100): 7025(low noise version) 12AD7,  12BZ7, ECC83, ECC803S, ECC803, E83CC, 5751, 6681, 7025, 7058, B339.

[FullRangeMan]

Thank you. Glad that I got your attention. Do you have any recommendations for power tubes? What I am looking for is a no coloration but warm equally balanced sound.Monitor audio RS6 is bright on the upper frequencies as you might already know.
Do I need to change all 4 powertubes at a time. I was thinking of changing one channel(one pair) to see the difference.

Do I need to change all 4 powertubes at a time. I was thinking of changing one channel(one pair) to see the difference.
This depend on the Bias, how is the Bias in this amp?? Manual biased for each power tube or biased in pairs??
If biased in pairs you need change the tubes in pairs and replace with a matched pair.
Looks good see the user manual for that bias detail to know what the manufacturer recommend.

[kinku]

Thank you Fullrangeman.
The manual is missing.I tried to mail cayin but no luck.
As far as biasing goes it has 4 power tubes and has bias test points for each one and has 4 bias pots numbered V1-V4 corresponding with each powertube. Hope this means each tube is biased seperate.

[FullRangeMan]

Correct. Individual Bias is a good thing, better than bias in pair sets.
If you substitute just one tube, maybe you had to compensate for the bias of a new and an old tube in the same set.
I unaware this detail, so I can be wrong.
Good luck.

[kinku]

Thank you.I thing I would go with pair powertubes to be on the safer side. Better chance of selling if I did not like it. I am still swimming in deep sea of power tubes to figure out which one to float with before settling. I would appreciate if you all can suggest few tubes which might work well with a bright speaker like Monitor Audio RS6.I love this speaker for it mid and high but if not careful ,it overwhelms the listening and it has some inherent difficulty in bringing up the bass.I know it does make good bass response but brightness seems like the issue, if you are not careful in selecting sources and amps.Please do not suggest to get rid of it.It is like a borderline girlfriend ,that one can never get part with but if not careful will give you a headache. Still she has a lover.

[Ericus Rex]

You'd actually have an easier time reselling a matched quad then a matched pair.  You'd also get a much more accurate idea of the overall sound if you change all instead of just one side.

In addition to the Gold Lion reissues, some people on here really like the Penta KT88SC.  I've never tried them:

http://www.dougstubes.com/power-tubes/6550-kt88/penta-kt88sc.html

Doug's tubes also has the GL for about the best price you'll find.  I'd say these two are probably your best of the affordable options.

If money really is tight for you right now, the Shuguang (sometimes called Sino brand) are cheaper and really don't sound bad.  Not as full and refined as the GL but better than most other cheaper options.

You also asked about using a 6550 tube.  In my experience, that tube sounds best in guitar amps.  In hifi it tends to sound rather nasaly and congested.  I'd stick with a true KT88.

[ltr317]

Thank you. Glad that I got your attention. Do you have any recommendations for power tubes? What I am looking for is a no coloration but warm equally balanced sound.Monitor audio RS6 is bright on the upper frequencies as you might already know.
Do I need to change all 4 powertubes at a time. I was thinking of changing one channel(one pair) to see the difference.

Hi Kinku,

If you want to change output tubes for more bass, I would follow Eric's recommendations about sticking to KT88s and changing all four.  There is another and cheaper way to experiment first if you don't want to spend lots of money on output tubes.  Do a google search for reviews of older RCA interconnects which provide better bass.  Decide on a model and then go to Audiogon or Ebay to find a used pair.  Most interconnect cables that are ten or fifteen years old will be fairly cheap by now.   If you find they don't give you the amount of bass you're seeking, you can resell them and not lose much money or if any at all.  You can always try different output tubes if this approach doesn't work for you. 

By the way, your statement that you want no coloration but also a warm equally balanced sound is a contradiction.  Warm is coloration.  No coloration is neutral as possible. 
 
I like some warmth, especially in the mid-range.  Neutral lacks life, soul and tonal harmonic colors, especially with most solid state components.  There are many tube audio components that are not overly warm and are almost as neutral as solid state equipment, but with a slight warmth to the mid-range providing some life and tonal colors to vocals and most instruments.  I think that is what you are trying to achieve with the Cayin integrated.  Correct me if I'm wrong. 

Cheers,
Paul Mah

[FullRangeMan]

Thank you.I thing I would go with pair powertubes to be on the safer side. Better chance of selling if I did not like it. I am still swimming in deep sea of power tubes to figure out which one to float with before settling. I would appreciate if you all can suggest few tubes which might work well with a bright speaker like Monitor Audio RS6.I love this speaker for it mid and high but if not careful ,it overwhelms the listening and it has some inherent difficulty in bringing up the bass.I know it does make good bass response but brightness seems like the issue, if you are not careful in selecting sources and amps.Please do not suggest to get rid of it.It is like a borderline girlfriend ,that one can never get part with but if not careful will give you a headache. Still she has a lover.

My 2 cents:
Seems your bigger prob is this speaker treble.
There is possible to modify the xover to perform a sweeter treble.
I unknow who I would suggest to you to do this correction service though.

[kinku]

Thanks for all your suggestions. Yes Paul it was mistake. I would like to have a lively warm midrange and that is the whole purpose behind getting the tube integrated. If you all suggest to go with KT88 that what I would go for.
Just curious any of you have  experience with Tungsol6550 reissue?
Fullrangeman Sorry ,I do not want to change anything on those british ladies,they are harsh but good.Just need to select amps and tubes carefully.Thats all.

[Ericus Rex]

My experience mirrors what ltr317 was saying.  I've found changing input and driver tubes to have a much more subtle effect on the sound than the power tubes.

FRM may have hit the nail on the head.  It is entirely possible that your new amp is allowing you to now hear the true character of the speakers.  And it sounds like you don't like what you're hearing.  ltr317's recommendation of older IC and speaker cables can be another option.  I do remember hearing some Tara labs cables about 15 years ago that were a bit dark sounding and could be great for your system.  You could probably find some of those for $20 a pair.  Tara also had a solid core copper speaker cable that darkened up the sound nicely.  I'm sure those are cheap now too.  My guess is they were designed for more inexpensive mid-fi equipment that was a bit hot.  You'll probably get the sound you want if you do most of the rec's given so far.

[kinku]

I get hold of a Toshiba Gigabeat player with rockbox installed and connected it to pre amp in of Cayin A70-T.Turned on the EQ settings and there is everything I wanted.The Bass treble and warmth of mid. Does it mean I need to look for a pre amp with bass and treble settings to work with this amp? It sounds good now.Do not seem like a powertube problem then.

[kinku]

I got deviated a little bit,but back on track again. I am wondering if yall can give some details about various pre amp tubes and their tonal qualities.I am going for tube rolling.Sorry nothing exotic please.

[mjosef]

I got deviated a little bit,but back on track again. ...I am going for tube rolling.Sorry nothing exotic please.

Really...then stay away from the TS 6550 reissue, nothing warm and cuddly about that tube, ballsy and muscular yes. One the 'newer' KT88, you should like the Gold Lion reissue KT88, very cuddly without the flabbiness.
Change out one set of tubes at a time, get used to the sound for a couple week (if new tubes). Create that baseline.
Sky's the limit .
 

[underdawg]

I would recommend KT 88 as I took out GE 6550's out of mine and went to JJ telsa blue kt88's which were a great improvement in my Cary amps.

[underdawg]

On the preamp tube I use RCA command  tubes 12au7 and 12ax7. I have found them to last forever, mine have no microphonic issues, and ample supply around.

[rollo]

My experience mirrors what ltr317 was saying.  I've found changing input and driver tubes to have a much more subtle effect on the sound than the power tubes.

FRM may have hit the nail on the head.  It is entirely possible that your new amp is allowing you to now hear the true character of the speakers.  And it sounds like you don't like what you're hearing.  ltr317's recommendation of older IC and speaker cables can be another option.  I do remember hearing some Tara labs cables about 15 years ago that were a bit dark sounding and could be great for your system.  You could probably find some of those for $20 a pair.  Tara also had a solid core copper speaker cable that darkened up the sound nicely.  I'm sure those are cheap now too.  My guess is they were designed for more inexpensive mid-fi equipment that was a bit hot.  You'll probably get the sound you want if you do most of the rec's given so far.

  Would that be Tara " Space & Time" cable ?

charles

[Ericus Rex]

  Would that be Tara " Space & Time" cable ?

charles

Sounds right.  But it's been so long....  Is the "Space and Time" the IC or the speaker cable?