The Black Adder
07-01-2014, 13:27
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! :eyebrows:
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:
http://i457.photobucket.com/albums/qq295/musical_submarine/AOS%20system/DSC08394.jpg
http://i457.photobucket.com/albums/qq295/musical_submarine/AOS%20system/DSC08397.jpg
http://i457.photobucket.com/albums/qq295/musical_submarine/AOS%20system/DSC08393.jpg
http://i457.photobucket.com/albums/qq295/musical_submarine/AOS%20system/DSC08389.jpg
Cheers
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! :eyebrows:
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:
http://i457.photobucket.com/albums/qq295/musical_submarine/AOS%20system/DSC08394.jpg
http://i457.photobucket.com/albums/qq295/musical_submarine/AOS%20system/DSC08397.jpg
http://i457.photobucket.com/albums/qq295/musical_submarine/AOS%20system/DSC08393.jpg
http://i457.photobucket.com/albums/qq295/musical_submarine/AOS%20system/DSC08389.jpg
Cheers