** "I pray, you pray, we all pray for Footscray" !!
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Such a beautiful amp with sound to match. Coupled with one of the world's best R2R DACs makes fine music. And great book beneath your HP8."A foolish consistency is the hobgoblin of little minds." [Self-Reliance: Ralph Waldo Emerson] Thus, an inspired consistency is geniusAll-Raytheon 'roll': pair 6SN7WGT, single 7728. Such contouring, layering within soundfield; such extension and texture of low & high frequencies; such vocal purity.
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• Another good job by @geoffalter11@jonathan c would love to help! He is the tube aficionado around these parts...
Congrats on your new amp, and what I think we all feel on this thread is a big time upgrade. Those are great amps, but just wait til you hear the HP8. Especially the bass and that midrange that is like a warm summer breeze. Just so easy and wonderful. This amp is utterly fantastic. It is 17lbs of perfection. With any SET amp, especially this one tube rolling won't change the sound quality, but will change the flavor of the amp, up to the tolerances of the tubes. 8-10% or so... David Shaw will tell you that the tubes being sent are all you need and that he cannot hear a difference between tubes rolled into the amp. This is exactly what he wrote me about tubes for the HP8.
Regarding CV181s, I think they are very similar (maybe some smoke and mirrors here). I use a HP8 personally and what people forget is that any peculiarities that a tube (or transistor) has will be ironed out by the local and global feedback, as all tubes are different anyway.
"I sold 100 Mullard 12AX7s last years and tested them first in an AVO tube tester and then in a HP8 with a scope and signal generator. Out of the 100 some were quite poor, especially balance between the two halves, some with low emission. They all performed flawlessly in the HP8 with channel balance within 0.2dB exactly the same output. I was really surprised!
Even premium tubes can be down 50% on one half, tubes we supply for the HP8 worse than 10% we reject and we also check for noise and microphonics (which premium tubes are no better)."
"I am inclined to agree that all your comments are valid especially as you have not automatically clouded your judgement “that I want these tubes to sound better because I bought them...
Sadly (for me) I am sure that you have better hearing than me so am greatly encouraged by your comments."
These are all comments from David, the designer and builder of this amazing amp. That being said, I heard differences. Here are some of my favorites.
Raytheon VT-231 (any of the VT-231's from wartime are amazing)
RCA Grey Glass Wartime 6SN7GT - The Victor's from 1949.
Raytheon 6SN7GT 1956
RCA 6SN7GTB Narrow Gap Plates - These are amazing!
These were the 6SN7s I liked most in the HP8. I also greatly preferred the 12AT7 as the lower gain provided greater headroom and dynamics.
. For the 6SN7 tubes, "V2" and "V3", I will add Ken-Rad VT-231, Sylvania 'yellow print' 6SN7. For ne plus ultra ... Melz 6N8S (late 1950s, late 1960s vintage).
The only alternative that comes to mind are 2 x 6J5 tubes per 6SN7. These would need a @Deyan - built pair of adapters; there might not be enough space for all this atop HP8. Otherwise, no. Icon Audio HP8 was designed to use 6SN7 tubes.Thank you @geoffalter11 and @jonathan c for the insights! I wonder if I’ve made the wrong decision to ask because now I’m slipping down the rabbit hole of searching for the best tubes combination again
Looking at eBay, a matched pair of NOS 6SN7s is much more expensive than NOS EL84s. Are there good substitutes for 6SN7 — like how one can roll 12AX7, 12AT7, or 12AU7 interchangeably? I love the extra headroom from my cryo-treated NOS Mullard 12AT7s, which are definitely getting some rolltime this Thursday.
Did you get the normal or signature? The ceramic CV-181s that come with the signature are fantastic. They will sound great! The amp sounds amazing especially if you roll in those NOS Mullards. Here are a few 6SN7s I would look to buy under $200 for a matched pair...Thank you @geoffalter11 and @jonathan c for the insights! I wonder if I’ve made the wrong decision to ask because now I’m slipping down the rabbit hole of searching for the best tubes combination again
Looking at eBay, a matched pair of NOS 6SN7s is much more expensive than NOS EL84s. Are there good substitutes for 6SN7 — like how one can roll 12AX7, 12AT7, or 12AU7 interchangeably? I love the extra headroom from my cryo-treated NOS Mullard 12AT7s, which are definitely getting some rolltime this Thursday.
I don't know your budget, but if you have cryogenic treated NOS Mullard 12AT7 that are NOS, then you are serious about your tubes. This is just one seller, but the seller I trust the most on eBay. There are some options. Those Westinghouse won't last long. They are the golds, and are as good as anything you will find under $300.
Here is one more from another great seller @jonathan c and I both use.
One more. These are an absolute steal at the price for 1951s... They are virtually identical to the Ken Rad VT-231. But they have a base crack which is why they are so cheap. They are usually double this cost.
