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Thread: AD Audio bespoke fully balanced valve buffer stage

  1. #1
    Join Date: Jan 2008

    Location: Norfolk, UK

    Posts: 6,209
    I'm BigBobJoylove.

    Default AD Audio bespoke fully balanced valve buffer stage

    Well, after having built my system into a powerhouse, I thought it may be possible to get 'more more more' from it, in particular a bit more warmth.

    After having read countless threads over the years on the gloriousness of valves, I headed into internetland to chat to folk, on here if I'm honest. After a short thread, David Coe over at AD Audio sent me a PM. We chatted for a few messages and he said he could build me a bespoke, fully balanced, valve buffer stage to sit between my DAC and power amp. Why not I thought? If the valves don't add anything then I can always move it on.

    Well, how wrong I was! After a few weeks my beautiful buffer stage was ready. Fully balanced, built by hand, and sporting a pair of NOS Sylvania 6SL7GTs that David supplied with it, and a lovely email on the layout of the sockets, switches and additional features. I shut the DAC and power amp off, added in an extra set of XLR cables I'd already purchased (to match the existing set), set it on the plinth I'd already set up, plugged in the mains to the socket I'd already run from the conditioner, powered up and waited an agonisingly-long ten minutes to wait for the valves to warm up a touch.

    I was sitting on the sofa with my girlfriend Rose, whom in fairness uses the system far more than I do, and we sought one of her favourite tracks on YouTube Music.

    So, what difference did it make? Well, I shall copy in my email to David which I sent shortly after a night-long listening session...

    Hi David,

    Just to let you know that the buffer stage arrived safe and sound. I set it up last night and let it warm up for ten minutes, and then me and my girlfriend ended up listening through to the midnight hour.

    What an incredible piece of kit! Where do I start?

    Well, the combo of the Leema Elements and the Bel Canto Ref500S was already a good one; but very clinical in its combined nature. The introduction of the buffer stage has brought much more to the party than I’d ever have imagined.

    Firstly, there’s that bass! Weighty, warm, powerful, clean and so easy to follow in the mix. This was the combo’s biggest failing to my ears; it was too lean before, but not now. It feels like the bass I got from my Arcam A85 amp, but so very much more - and so much cleaner and smoother.

    Then there’s the vocals; simply astounding. The Reiver Edingdales were already exception in the vocal band, serving them up right in the middle of the room. But now the voices are even clearer, erringly so on some tracks. And they’re so much clearer too.

    Prior to the buffer going in, the combo have a tendency to express sibilance on some recordings, so much so that I had to back off the ribbons on the Edingdales (thankfully Colin put an L-Pad resistor on each speaker). Well, back up to 0dB they went. The sibilance is gone, but the treble crispness remains, and in fact has become even more detailed.

    What has really struck me though is the ultra-short transients; the clicks and snaps and ticks that embellish so much of today’s electronic music just sound so clean and tight that it’s hard to believe they were missing in the first place. There’s just so much more of everything. Even if the system is playing in the lounge whilst I work in the office, I can hear so much more - and then there’s the bass again. I had to fiddle with the subwoofer controls slightly, raising (oddly) the cut off frequency, and that’s made the low mid bass just perfect.

    Also it looks really cool standing on its own acrylic plinth and AIEX resonance absorbers.

    So I thank you for your fine work sir, an absolute triumph. There’s everything to love about the improvement it’s brought, and not a single thing that’s diminished in the system. Perfect and worth absolutely every penny.
    So that sums it up nicely. Since then I've purchased a brand new set of Tung-Sol 6SL7GT gold tips (not here yet, but only to keep as spares) and a pair of Russian Melz 1950's metal base, military grade 6H9Cs from Alf (Alfonzo) on here. Those valves are currently in place, and they are so much better than the Sylvanias. Seriously, the uplift in quality is mind bending. The treble and mids are frighteningly airy, the vocals are so clear and close that I swear there's more people in my lounge, and the bass is so tuneful, weighty and clear that I wonder how people can go through their hi-fi lives without having valves in their set up.

    I'm now on the lookout for more of the 50's NOS 6H9Cs to keep a bank of them in stock, hopefully I'll be fortunate enough to find some with the holes in the anodes, but I'm seriously wondering how much better they could be.

    Here's a couple of shots of the buffer, worth every single penny, and then some, of the £800 I paid for it. It's added soooo much to the performance of the system that I can barely believe it. I added the 'nose' over the power LED as it's quite bright, somehow its look reminds me of the Dartzeel amplifier that has garnered so much praise; NH108 is it?

    So a HUGE thanks to David Coe at AD Audio. He's a fine, fine gentleman to deal with and he kept me in the loop every step of the way. His work is superb, the build quality of this buffer has to be felt to be believed.

    Me out, going to have a listen. I will get round to getting a longer XLR by the way.








  2. #2
    Join Date: Mar 2016

    Location: Brighton, UK.

    Posts: 3,071
    I'm Mike.

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    What does a buffer stage do??
    Current system 1210 GR. CDP - Meridian G08. Amp -Sugden A21I - Sig. Wharfedale Lintons.

  3. #3
    Join Date: Jan 2008

    Location: Norfolk, UK

    Posts: 6,209
    I'm BigBobJoylove.

    Default

    It receives a line level / balanced input and passes it through the valves to a line level / balanced output. Essentially it’s like adding valves to the pre-amp.

  4. #4
    Join Date: Oct 2012

    Location: The Black Country

    Posts: 6,089
    I'm Alan.

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    It improves the matching so the music flows better.

  5. #5
    Join Date: Feb 2016

    Location: London

    Posts: 876
    I'm Don.

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    Great write up. Looks good too!
    Nice one David!

    Sent from my ONEPLUS A6013 using Tapatalk

  6. #6
    Join Date: Jun 2015

    Location: London/Durham

    Posts: 6,869
    I'm Lawrence.

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    Quote Originally Posted by Mikeandvan View Post
    What does a buffer stage do??
    If you're wondering if it will help with your situation you could try a Musical Fidelity X10D, it won't be as good as this but you can pick them up cheap on eBay.

    Sent from my HRY-LX1 using Tapatalk

  7. #7
    Join Date: Jan 2008

    Location: Norfolk, UK

    Posts: 6,209
    I'm BigBobJoylove.

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    Quote Originally Posted by Lawrence001 View Post
    If you're wondering if it will help with your situation you could try a Musical Fidelity X10D, it won't be as good as this but you can pick them up cheap on eBay.

    Sent from my HRY-LX1 using Tapatalk
    Indeed. If you like what it does you can ‘go larger’, if not then sell it for the same money. They were quite popular in their day, and remain saleable.

    Quote Originally Posted by Firebottle View Post
    It improves the matching so the music flows better.
    You put it so much better than me!

  8. #8
    Join Date: Mar 2008

    Location: Galashiels

    Posts: 13,669
    I'm inthescottishmafia.

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    Looks good Rob, glad it's doing the business.
    “Music has always been a matter of energy to me, a question of fuel. Sentimental people call it inspiration, but what they really mean is fuel. I have always needed fuel. I am a serious consumer. On some nights I still believe that a car with the gas needle on empty can run about fifty more miles if you have the right music very loud on the radio”

    Hunter S Thompson

  9. #9
    Join Date: Jan 2008

    Location: Norfolk, UK

    Posts: 6,209
    I'm BigBobJoylove.

    Default

    Thanks. It most certainly is!

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