The new AOS classic series amplifier by Tube Distinctions

[The Black Adder]

Hi all.

Over the last year I set upon the decision to re-vamp the AOS classic series amplifier. Originally Steve Toy commissioned this already lovely sounding Pure Sound A30 to a spell with Anthony at Tube Distinctions bringing it away from being an integrated amplifier and in to a purely superb stand alone power amplifier.

Well, it's been a few years since Steve had the amp and two very happy owners later the amplifier came back to me from Anthony after some major heart surgery. That is to say the amplifier now no longer resembles the original A30 in circuitry/sound terms and has been updated to the hilt!

And yes... it now has a new heart, oh yes folks!

The original PSU has now totally gone as it induced noise through the speakers due to the coupling effect with the metal chassis. Generally this would not be noticeable with less efficient speakers but with my Tannoys (15" Monitor Golds) being so sensitive it needed to be addressed.

So now it has a brand new heart in the form of a HUGE top quality external power supply and dual chokes. This baby is now simply something truly magnificent in the way it articulates the layers of music. The bass is so effortless and is really quite something. I'm finding sub bass existing where I never thought it was before and with that brings even more presence, really quite eerily so in a lot of cases. The best way to explain it is that it's the most realistic I've heard up to now, sumptuously engaging.

The amplifier in this current re-configured form is designed to run the bonkers KT120's and the KT150's (as well as the original KT88's). So lots of options there for taste. The two GZ34's are now super diodes which form a newly added function of a HT switch (standby) so once the amp is fully warmed, the standby switch can be operated, putting the amp into a form of rest mode ie; no HT voltage, just heaters. Very handy indeed. They are also kept in the circuit primarily to maintain the soft start function that indirectly heated rectifiers like the GZ range offers.

The way that the standby switch is configured in this amp is quite unique as far as valve amps are concerned' in that it starts the soft start process again exactly like from cold, so the valves get a much easier life coming off standby, and of course there is no audible thump in the speakers which has become accepted as normal with some amps, which for delicate drive units such as Vintage Tannoys is added piece of mind.

The first gain stages are now completely different from the original circuit, and near perfect balance is achieved in the phase splitter, and output valve driver stages which in turn further decreases distortion, and the need for high levels of over-all negative feedback is also greatly reduced whilst still maintaining a wide and flat frequency response at both ends of the audio spectrum, and without compromising bass control.

I am in ore at what Anthony has done to this already great sounding amplifier and with this thing gripping the Tannoy's as tight as Lord Flasheart's codpiece.... A-HAHAHAHAA! - I'm a very happy bunny!

Some pics:









Cheers

[synsei]

Congratulations Joe, it's a wonderful looking thing too and I wish you many happy hours of musical nirvana. Happy New year dude

[Marco]

Great pics, Joe. The amp looks fab! Is the wooden casing just a surround that the original amp casing sits into or is it a whole new dedicated casing? Pleased to hear that the amp is sounding fab, too... How is it gelling with your Croft?

Oh, and any chance of some full system shots, showing that lovely room of yours in all its retro splendour, as well as your Lockies with external crossovers? We need some more audio porn, man!

Marco.

[Alex_UK]

Looks fab Joe, and knowing how Anthony works his magic I can well believe it sounds it too.

[The Black Adder]

Congratulations Joe, it's a wonderful looking thing too and I wish you many happy hours of musical nirvana. Happy New year dude

Hi Dave. Thanks man. Nirvana.. well, I really do think that I've got it... finally!

Great pics, Joe. The amp looks fab! Is the wooden casing just a surround that the original amp casing sits into or is it a whole new dedicated casing? Pleased to hear that the amp is sounding fab, too... How is it gelling with your Croft?

Oh, and any chance of some full system shots, showing that lovely room of yours in all its retro splendour, as well as your Lockies with external crossovers? We need some more audio porn, man!

Marco.

Cheers Marco. The casework is a surround I had made, the amp simply slots inside, nice and tight! It's a proper job with the base plate recessed and mounted on the bottom.

It's gelling with the croft really well. And it's just getting better and better as those SCR Teflon caps you suggested seem to release a little something each day.



I'm a bit embarrassed as our room needs decorating... lol - the wall looks like I've sprayed it with and AK-47... lol - We had some units as you rememeber and they left loads of now filled in holes. But I'll see what I can do as I've now got my vintage Psychedelic posters up. Kind of framed, but that's another story...lol

The crossovers are now behind the speakers but will be re-appearing later in (another form)...

Looks fab Joe, and knowing how Anthony works his magic I can well believe it sounds it too.

Cheers Alex. Yeah, it's simply stunning, make me want to not cook anything and just sit and listen. Even from in the kitchen it sounds utterly superb!

[keiths]

Very nice indeed Joe.

[The Black Adder]

Cheers Keith. Just a few more additions to go and then it's finished aesthetically too!

[Roy S]

Great looking kit, see you're still using the MP10.

[The Black Adder]

Great looking kit, see you're still using the MP10.

Thanks Roy. Yes, the humble MP10 has been in for a month or so now. It's a nice sounding cart and for the price I paid it's a good bargain. It's not the most revealing cart but it's balanced accordingly and doesn't try and do something it can't.

[John]

Looks lovelly