Tube Preamp Reviews

... Falcon Acoustics LS3/5a Gold Badge speakers, HR ought to consider getting an Audio Research I/50 integrated amplifier.
The I/50 costs a mere $1,500 more than the HE1 preamp.
If JA1 still has the review unit, could he send it over to HR for a follow-up?

https://www.stereophile.com/content/audio-research-i50-integrated-amplifier

https://www.hifinews.com/content/audio-research-i50-integrated-amplifier

I think I am still in the market for the Holo Serene KTE, given its competitive performance with the Audio G-D and the Lab 12. I may lean towards the Lab 12 given it's price and value therein.

What really impresses me is that these Chinese companies are using the best in audiophile parts extant and at a price point the rest of the world can't compete with. I still worry about our domestic and European counterparts though.

Kudos again HR. Your writing is always clear to me... and fun!

Hi Herb,

A great review, thanks. I am intrigued by your number of tubes theory -- very interesting; made me want to pull out my Wyetech Coral (3 tubes) and compare it to my BAT VK52SE (8 tubes).

Most of all, I really enjoyed loading up and listening to the three records you used in this review. I was particularly taken by "The Six Seasons." Some amazing double bass work ... really exciting!

-- Monty

Hi Herb,

As an avid Audio-gd customer & fan of at least a decade now, it gives me great satisfaction hearing your praise for their products. I have always believed that they provide a great cost to performance ratio, with no compromise to sound quality but I’m swayed from time to time by the promise of better from more established Western brands. I run a full Audio-gd stack and you’ve given me both validation and a possible upgrade path - I happen to have bren quite curious about their vacuum preamp.

Would love to see you complete the loop and review an Audio-gd power amp too.

Hello, y'all! I'd like to add my 5 cents to the discussion.
As was pointed out, PrimaLuna sounds radically better with NOS tubes.
As expected, really. And AudioGD preamp would do as well. However, most don't realize the international compatibility of the Russian, European and American tubes, and presume that such a swap isn't possible.
6N2P (or what looks like 6H2n in Cyrillic) is a direct equivalent of 12AX7 / ECC83, but with a 6.3V heater and a different heater pinout (12AX7 has 12.6V heater with a central point). And Ebay is full of 12AX7 to 6N2P converters that allow an easy substitution of the stock signal tubes in the Audio GD preamp for, say, Telefunken, Mullard, Mazda or Brimar ECC83. And those tubes will sound considerably better than a humble 6N2P. The only catch is to make sure that the adapter you're getting is for the ECC83 tube (top) and 6N2P socket (bottom), and not vice versa, and that requires carefully studying the Ebay item description, or even contacting the seller to make sure.
Same goes about the 6U4n tube, which is in Russian is pronounced 6Z4P (and is usually cited in this transcription most everywhere). It is, in turn, a direct equivalent of 6X4W / EZ90, again with a different base. And again 6Z4P to EZ90 adapters are plentiful on Ebay, allowing to use a GEC, Mullard or Brimar EZ90 instead of the 6Z4P / 6U4n.
One could also use octal tubes with additional adapters, allowing use of 6SL7 signal tubes and 6X5GT (EZ35) tubes, but they will most likely not fit under the top plate and thus require either to run the preamp open, or ordering somewhere a custom top plate with drilled holes for the tubes (which might actually add some visual charm Cary-style).
Finally, I would add that NOS Russian (USSR, actually) special quality tubes (-EV and rarely seen -DR versions) are quite good in their own right. So it is worth changing them only to the absolute best (and very expensive) NOS European tubes. If you're not ready to throw about a grand on those 10 tubes, it's not even worth the trouble. With all due respect, most regular US tubes like good old RCA and GE will most likely provide a different flavor instead of a real quality jump.
Hope this helps.

And Herb, thanks a lot for a great review!
You really got me salivating all over this preamps virtues, so I've bit the bullet and bought me a spanking new Audio-GD Vacuum HE1 XLR. Still waiting for it, though.
I will certainly do all the experiments I described above, including stuffing it with six huge new production Shuguang WE 6SL7 Plus and four NOS 6X5GT (pity that coke bottle 6X5G will not fit as the sockets are too close to each other). Together with a custom copper top plate that thing will look to kill! And hopefully sound amazing too)))

Nice review! As an owner of the Schiit Freya+, I’m definitely interested in giving this a go.

I emailed Audio-GD to get a quote for this preamp and the price before shipping is just under $3k. The reviews says $3999 and the pictures shown in the review show two different models (the Vacuum HE1 and the Vacuum HE1 MK2).

Which unit was reviewed and what is the US price?

Would love to support this company but their website is confusing and the review here doesn’t help.