Tube rolling in Cayin A-88T

I also love the Cayin A88T which I have owned for the last 7-8 months now. I am using the stock tubes and have been thinking of upgrading to the PentaLabs or the TungSol re-issues. This thread was just what I wanted.

I hope you guys are biasing the amp after tube rolling as this is not an auto biasing amp as some mistakenly believe.

I found one of my tubes having zero bias and I changed it immediately. The amp sounds much better now.

Kag,

I got the biasing info from Steve at Vas Audio in NJ. Seems relatively simple. Bias point of 0.4V (40mV) per tube. Clark at Acoustic Sounds was nice enough to have Vas Audio send the info to me. I will definately check bias and make sure the Tung Sols are set properly.

Ive had new tubes show 0 readings too. I have had more trouble with Ei tubes than others. The KT-90 TypeIII are notoriously bad for QC issues.

From what Clark says..he hears that the new re-issue Tung-Sols are wondeful in this amp, but take a bit of time to open up. Ill get back to this thread after they are in for awhile//Ken

Have you'll tried rolling the preamp tubes? I changed the stock 6sn7s to RCA 6sn7 GTBs and the sound improved a notch. Better soundstage, mellower and richer mids, surprisingly more detail in the mids and bass.

I did find trumpets on some recordings to be bright/hard on the stock tubes... for example, the trumpet on the track 'Papa a boo boo' on the German pressed CD of Harry Belafonte live at CG Hall was quite bright and hard sounding. This reduced considerably on the RCAs but it is still there. I wonder why? Could be due to the stock output tubes. I heard the Primare drive my speakers (Dyn 82s) and there was no hardness at all. My CDP is the Rega Planet which is known to be smooth. Interconnects are Transparent which is also mellow. So I guess the amp is the culprit.

Kag,

Haven't rolled the input tubes as yet. I have experience with the RCA grey glass VT-231 GT tube from the 50's. I thought it was definately a smoothie, but I actually liked the linearity of the stock EH tubes in my former Cary amp. The Cary definately needed the EH to sound alive. The RCA in the Cayin may be indeed a nice sound as you mentioned.

Ive yet to hear harshness from the Cayin with anything Ive played, except those discs/LP's known to be so.I recently played some trumpet from Rick Braun(Full Stride) and Chris Botti( A Thousand Kiss...) and man they sounded excellent!

Perhaps the RCA/Tung Sol combo would be very good together.

One thing to keep in mind is that the amp/speaker interface is all telling as well as you know.. It's likely the reason why you may have NOT heard the harshness with the Primare.

On my Ushers, if anything, I have a sound presentation that is more relaxed, yet very dynamic with the Cayin. I found that the 4 ohm tap didnt work as well as the 8 ohm tap and by a big margin. The 4 ohm limiting the dynamics and bass. And the Ushers are 4 ohm nominal

maybe try the 8 ohm tap if not being used would also be a suggestion. You shouldn't need the 16 ohm tap unless your speakers are rated as such or very high ohm/hi-sens types.

Just a thought.

Hoping the Tung-Sols arrive here soon!

As a aside note: When I ordered my 88T from AS's..I spoke with Clarke who recommended going with the KT-88 version. He thought it sounded better amp for amp and the 6550 version comes with EH 6550's.FWIW.

Are you guys using aftermarket powercords with the A-88t? If so, any suggestions on which works or sounds good? Thanks