Playtime new idea on severe amp control

Some new toys I am playing with, with A - A/B select and remote cable sense and Balance and Un-balance input Mono amps about 70W max 8Ohm. 1 channel shown here.

Each channel (1 shown) 4 off 47,000uF 2 off 300VA at 15V transformer. 12 output devices, 4 temperature sensors.Ag wire in PTFE for input and output wires. Poly Carbonate input caps. BW 1Hz - 400KHz flat 70W/8R 140W/4R bias from 30W Class A to 5W Class A in A/B mode. SECA driver stage max 140MHz BW to control with ease silly loads. Very expensive to make lots of time and very costly bits.


  • Well, hello!

    (How does it sound?)
  • Not switched it on yet it has taken two weeks to make it so far and 4 lovely days with maths and a drill. Board 2 to complete and mount then Alan will blow his neighbours away with it.
    I am hoping to get the DC offset to 10uV and drift of 5uV in 100Hrs max, Max Temp A/B Amb + 22C in AA/B Amb +40C
    Max cable sense depending on driver wire about 50M.
    Max sense current full power. 
  • Wowzers,  look like serious beasties.

  • Very interesting!
  • Watch out Alan's neighbours!
  • Muahahahaaaa..... 😈

    Best bit is the bias switching. It's a tame class A/B one way, no more than 30W consumption. Fine to be left on 24/7 on full time TV duty or whatever.

    Flip a couple of switches and it's class A monster substation... Let's find out what these Revels will do!
  • Picture of front panel, showing on/off L&R, and bias switches above (class A/AB), and a single switch for balanced/single ended input.

    The other pic shows both circuits and the four transformers placed in situ.

  • We'll be looking forward to your experiences with it when it has been tuned and approved by Colin.
    One of a kind or a prospect?
  • Well, this one is mine. It's proving super fiddly for Colin to make, which I feel guilty about. But when the next revision of the boards is designed and made, all these fiddly connections and wires can be incorporated into the PCB.

    To be honest, these sell in such low volume that each one is a custom build, so never say never...

  • Cool stuff.
  • Its growing 

  • All working.
    75W/8R 140W/4R as it is a pair of Mono Amps
    Low A Class setting 5W 8R
    High A Class setting 30W/8R
    BW 1Hz - 326KHz flat
    Balance or Non Balance input 1V full power.
    Input RCA 22KR
    Input Balance XLR 600R nom (1KR)
    Max short term current peak 62 Amps 
    Damping Factor (silly)

    To select amp function there are switches to select Balance and High/Low A Class
    THD Low A Class 0.001% into 8R at 20Hz - 50KHz
    THD High A Class ( silly) 0.00001% 8R at 10Hz - 100KHz

    More tests to be done on sense load input.
  • The beast goes to Alan on Monday so those within 50 miles move now.
  • 😬
  • I may be just on the edge of the destruction zone.
  •  Night time, stealth mode...

    Not so stealthy. There's a pleasing aesthetic to the beast in my opinion, a sort of '80s lab-test-gear-chic, which I just made up.

    And it sounds at least as good as it looks! 

    I'm not sure what to say about it at the moment regarding SQ. First impressions are a massive, full low end, presence and pace. Superb imaging, detail and texture but also a warmth, a delicacy for the subtle stuff. I've heard a lot of the Wonf amps but I think this is the best, and by quite a lot!

    It's the perfect partner for my Revel F-208. 

    Perhaps Colin can give some impressions as well? You were here for three hours or so, and you've heard a lot of systems in your time?
  • Jealous vibes emanating from West Sussex :-)
  • From Lincolnshire also.
  • ...and from other places on the planet!
    >:) :*
  • That is 100% wow.
    Mega jealous.
  • Even in Somerset ? or Basildon maybe ?
    Well one more to make for me, bass was like a huge truck driving into the wall like seismic quake,,, the image was like 3D and the strings you could hear the woodworm singing along. The slam on all the front edges was real live and amazing. well I must stoppppppp  has this fucking keyboard aaaaaaaaaaah the stuuter agani watch out world I am going to chuck the fucking thing. Bloody HP ssssssssssssht

  • AntiCrap said:
    Well one more to make for me, 

    How very selfish. I would have thought at least 2 or 3 each for everyone here at least.
  • I love to but Dave said it rather have a SECA
  • As ever, he’s behind the curve. ;-)
  • Always behind the curve.
  • I really have to go to work... πŸ™„
  • edited March 13
    Hi Col, thanks for your comment!

    We played a track by PanSonic from Katodivaihe (Cathodephase) called Virta 1. This EP is to all intents and purposes a hifi torture fest, and is interesting if you enjoy electronic music. The bass was literally propulsive, I don't think I experienced anything like this before. Vibration of the wall, sofa, the air between my hands. It's a good thing my neighbor was out! Yet Colin and I could still converse without raising our voices. 

    Using the amp without its feed forward wiring first, we watched in amazement as the twin aluminium bass drivers performed acrobatics and wondered how the sound wasn't distorting in any appreciable way (I had never seen then move until now). This sound very much the same as the M-100T I had here for a while. Colin smiled the satisfied smirk of a designer who knew he has knocked out out of the park - again.

    Adding the feed forward was fascinating. The drivers appeared to barely move in comparison, the twisting at the end of their travel was utterly eliminated. So strange to see a visible manifestation of this feature!

    As for the sound, it did that thing you might remember when you first heard a SECA amplifier. That wonderful infusion of subtle detail, superlative speed and convincing warmth, the sound now coupling with and driving the room like you'd not heard before after listening to transistor amps with dampng factors of around a hundred; now a SECA with a DF of thousands could intimately connect you with the music. A performance rather than simply music. Similarly this amplifier can do even better and above a SECA, but at any volume level. This in turn throws the sound image forward and spreads it wider.

    We also played 'Love turns forty' by Vienna Teng, which is the other track I think Colin refers to. It's a lovely detailed recording with a double bass. And Lia Ices 'Daphne' for that matter, which also features a string section. Colin is right, the wood body of the cellos and bass was so vivid as to really be striking.

    The aspect I'm appreciating most right now is the bass depth and power being present at low volume, the system coupling to my rooms acoustic. The extra control finally sates a desire for scale and presence at any volume, full musical body and texture at low volume with huge imaging. Yet at high volume it appears not to be loud at all (an illusion), but rather bigger. More powerful. More insistent. More - just more. Effortless. Arresting.

    This amplifier seems to be so fast, so capable that it doesn't even have to try. The Revels appear to match it's abilities foot for foot, and are just as impressive a piece of engineering. I don't doubt which would ultimately win though, this amp being capable of 64A output into DC! However, I would be Deafened long before that. This is a fascinating exercise in building a system around superb engineering, and the music taking care of itself.

    Thank you, Colin. πŸ€—
  • edited March 17
    Power Amp PCB artwork.

    The DC Blocking,SSR,SS and filter PCB.

  • Hi Col
    Your images aren't appearing because the URLs aren't valid - invalid time stamp, apparently.
    Is there another URL you should be using?

  • They're fine with Android phone.
  • They're not working on Chrome on my Mac. I guess Colin must have posted the URLs from a Android app.
  • No under Chrome try this one.

  • Nope. Can't see that either :/
  • Weirdness! I can see the images on my Chromebook, so it must be something to do with the Mac setup.
  • Buy from KFC instead
  • AntiCrap said:
    Power Amp PCB artwork.

    The DC Blocking,SSR,SS and filter PCB.

    "Art work" is the term! :-)
    Hopefully they sound at least as good as they look.
  • (No problems viewing them in Chrome on Windows 10.)
  • AntiCrap said:
    Buy from KFC instead

    Self-isolation stops all junk food :-)
  • uglymusic said:
    Weirdness! I can see the images on my Chromebook, so it must be something to do with the Mac setup.

    OK. It seems something was probably up with the cookie (I am always a fiend for biscuits) on the Mac. I logged out of Chews and in again and voila! I have the works of Van Wonfor :-)
  • You don't need to see it, I can just turn it up a bit, and everyone can listen! 😲
  • We're listening!

    Photo by kyle smith on Unsplash

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