Want more high frequency extension

Trelja...While I cannot disagree with your preference for low (or zero) feedback amps, I have difficulty believing that the difference you hear derives from greater bandwidth. Reduction of feedback will change the sound so that it reflects the characteristics of the amplifier, (most likely the output transformer) rather than the input signal. I would expect the bandwidth to be less with low feedback, and this may emphasize harmonics in the 12 to 18 KHz range that you may find pleasing.
The ability to vary the feedback is interesting. Do you have, or can you generate frequency response plots for various degrees of feedback?

Also, is the amp really "zero" feedback? No local feedback around stages, or "ultralinear" transformer windings driving output tube grids?

A schematic would be nice.

Mattybumpkin...A word of encouragement!

You, like eveyone else, have lost, or will lose high frequency hearing. When tests are run, (at least on me) sine waves of various frequencies are used. I cannot hear a sine wave much over 10 or 12 KHz, but I can clearly detect the action of a supertweeter or a filter operating up around 20KHz. My theory to explain this is that the ear senses rate of change of pressure as well as pressure change, and the steep wavefront of the HF sound is sensed, even if the frequency is not. Hey..it works for me.

Also, loss of HF hearing does not, at least for me, affect spatial perception, eg: imaging.

Thank you everyone for the responses.

I am sure my hearing is still good even though from reading the posts here it sounds like I have one foot in the grave. Who should I leave my rig to in my will?

I think I will begin to roll some tubes in the amp first, and if that still doesn't float my boat maybe I will try another pre.

Trelja, I would be curious to hear your impressions of the EL34 tubes you just got. I was thinking of trying the EH EL34's, supposed to have more sparkle up top. I know the comments you mention about the Cary V12 and the attempts to use the other tubes like KT88, etc. I wonder though, the Six Pac's are different circuitry than the V12I that was mentioned in the other thread. The new V12R is supposed to be the same pretty much as the Six Pacs. I wonder if this would make the outcome different. I'll ask Dennis I guess, or Kevin at Upscale. KT88's are more extended than EL34's, yes?

Regards,

Oh,

Tvad, I did roll back into the AI L-1 some EH 6922 that I had. It did provide some extension. Thank you. I may try to hunt down a pair of the Siemens you mentioned.

Regards,

Very pertinent points you raise, Eldartford.

While the Granite schematic is available to me, I have not asked for it, and do not have it. From their advertising, the amp is zero feedback, based on that setting. A switch controls whether the amp runs in triode or ultralinear (pentode), which I keep in triode with the KT88 tubes. And, while I have not measured the sound using feedback versus no feedback, it is instantly apparent there are dramatic differences between the two. Others who have come to listen cannot believe the degree. I could plot a response curve using a test CD, but in all honesty (and not to be a wiseacre), I always prefer listening to music as opposed to test tones.

I also concur that loss of HF hearing should not be used in any way, or at any time, as a barometer of one's ability to judge a system. Using a test tone (yes, I do use them at times), on my Fried speakers, I was able to hear the 16 kHz tone, but not the 20 kHz. I didn't much care, as I said, I prefer listening to music (which I probably the reason I didn't then go try the 20 kHz tone on my Coincidents), but the Frieds are only rated to 18 kHz, so I am now unsure if my inability to hear the 20 kHz tone was a reflection of the speakers or my own hearing. I do know most men cannot hear to 20 kHz.

Mattybumpkin, I gave the JJ E34L tubes a go last night. They were much less sparkly than the JJ KT88, so that should be a real consideration in your quest. Whereas the KT88 have a beautiful, sweet, extended signature, the E34L were much more flat in tone. It was akin to adding feedback, but not to the same degree in terms of magnitude. The KT88 were obviously much more powerful and extended at both ends of the spectrum.

I then leveled the playing field a bit by then running the E34L in ultralinear. While the sonic signatures of each tube remained, the power differences were more or less canceled. The E34L produced better bass than I expected, but the KT88 were still superior.

Based on what I heard last night, and what you are looking for, the KT88 are the more than obvious choice. Still, as you pointed out, you will have to wade into these waters VERY carefully, to avoid the issues others have faced in running this tube in the SixPacs. Due to the cost of the larger tube, it is not something to get into without being certain of the result.

Good luck!