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Playtime new idea on severe amp control

CJ14

O.H.
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.

88044728_2265603430409252_8990967138810331136_o.jpg


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.
 
Loving the way you're easing into retirement there Colin :D

Nice work BTW! i just spent the best part of a week planning, modifying/upgrading and totally rebuilding this from bare chassis:


It was physically making an annoying very low level two tone hum which turned out to be one of the 18000uf/63v capacitors. Now all 8 replaced with 22000uF/63v Mundorf M-lytics.
You should try them, they are definitely worth it - a justifiably upgrade.
 
The ESR is the problem for me if the ESR is to high,higher than the Xc I cant suck current out fast enough to get the rising edges faster has I would like and the falling edge. This beast has a rise time of 60nS with a 1KHz square wave a little slow I must whip it up a bit. I think I will fit some ITW Paktron cap on it and go to from 2oZ PCB to 4oZ PCB material and maybe from 2 to 4 layer to reduce the skin effect on longish tracks.
 
So whats it gonna be when it grows up?

It's gonna be mine!

It will have 30W pure class A output then push pull, doubling into everything down to about a half ohm. It's for my new Revel f-208. (Colin always states power output very conservatively, this is likely to produce 100/8R all day long.)

The feed forward sensing connects an extra set of cables to the speaker terminals. This goes back to the amp, which corrects for cables and losses. It's like a direct connection to the speakers.

There's also a feed forward system going between the matching pre and this power amp (balanced only).

Other cool features include bias switch. It's a class A/B, cool running amp by day (tv duty etc in the lounge) and a class A, hot blooded beast when it's listening time.

The whole system is true dual mono, balanced bridged. Also it has internal balanced mains supply, like the EWA M-100 (which this is based upon).

It is a slightly smaller version of Colin's largest EWA amplifiers, but with interesting SQ tweaks and experiments to keep my mad scientist friend interested!
 
Nice. A proper grown up amplifier. Colin is a star for sure.

Grown up. Wonf. o_O

@Alan Brown So like an M-100 Turbo with NOS :D

Assuming you mean n2o, this is slightly smaller than the M-100 but it has more in common with the turbo version, hopefully will sound better. It's lacking one pair of output devices due to the smaller case, but I'm not chasing absolute power.

(New Old Stock? Non Over Sampling? Not Overly Sensible?)
 
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.
 

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! o_O

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. This makes for an interesting combination with the savage speed and control. I don't get tired listening at silly volume levels (which will soon stop, as I prefer it a fair bit lower). I have 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.
 
"
Alan
10:00AM edited 10:01AM Flag
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. "

http://www.audiochews.com/discussion/2360/playtime-new-idea-on-severe-amp-control#latest
 
Superb; congratulations on a fantastic new addition to your set up.

I love it’s uncompromising and functional looks.
 


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