The primary difference was a JFET input stage on the 1A,
replacing bipolar devices.
I don't seem to have a schematic, but the circuit was ordinary
enough - N channel JFET diff pair followed by a PNP common
emitter voltage gain stage, both of these constant current
sourced. Vbe multiplier for the bias, and complementary
emitter followers for output stage biased into Class A. Very
simple.
replacing bipolar devices.
I don't seem to have a schematic, but the circuit was ordinary
enough - N channel JFET diff pair followed by a PNP common
emitter voltage gain stage, both of these constant current
sourced. Vbe multiplier for the bias, and complementary
emitter followers for output stage biased into Class A. Very
simple.
My first NP amplifer too.
Recently i read your question from a couple of months ago.
The Forte Model1A combined very well with Quad ESL's.
I have not heard it on Audiostatics, the 200's are a lot easier to drive than 63's though.
The Model1A i compared to the Audio Analyse A9, a 50 watt class A amp, and the JH50, an EL34 tube amplifier from Jean Hiraga.
All three i heard on the ESL's and the 1A sounded way better.
Mr Pass prooves he can toss out half of the components, if i had the brains to think of the circuit i could have built it myself.
The 1A was rated at 50 watts i think, Audio or Stereo measured it at over 60 continuous output.
The 1A was even the cheapest of the 3, call me Dutch
(3000 DM for the 1A, 3800 DM for the A9, the JH50 was 5000 DM in Holland )
Recently i read your question from a couple of months ago.
The Forte Model1A combined very well with Quad ESL's.
I have not heard it on Audiostatics, the 200's are a lot easier to drive than 63's though.
The Model1A i compared to the Audio Analyse A9, a 50 watt class A amp, and the JH50, an EL34 tube amplifier from Jean Hiraga.
All three i heard on the ESL's and the 1A sounded way better.
Mr Pass prooves he can toss out half of the components, if i had the brains to think of the circuit i could have built it myself.
The 1A was rated at 50 watts i think, Audio or Stereo measured it at over 60 continuous output.
The 1A was even the cheapest of the 3, call me Dutch
(3000 DM for the 1A, 3800 DM for the A9, the JH50 was 5000 DM in Holland )
Has anyone turned up a schematic for the Model 1 or 1A?
Used Model 1's are coming onto the market and I want to be prepared.
It seems there's an upgrade article for the 1A in
audioXpress May 2003
* "A MOSFET Update of the Forte 1A Amplifier, Pt 1"
which I probably have somewhere. But I'm thinking of purchasing a Model One since the price is right.
Used Model 1's are coming onto the market and I want to be prepared.
It seems there's an upgrade article for the 1A in
audioXpress May 2003
* "A MOSFET Update of the Forte 1A Amplifier, Pt 1"
which I probably have somewhere. But I'm thinking of purchasing a Model One since the price is right.
If you were the new father of a Model 1, what would you do to it?
The Audio Amateur article (thanks Walter) is almost a complete replacement reusing the power supply and chassis. It's basically a new amp when you're done. (I do have some unpopulated A75 PCB's laying around, perhaps an A75-lite?)
Is there something less drastic you could do, other than replacing the now old electrolytics caps?
(Have soldering skills, not design skills, yet)
Still haven't found a service manual for this yet. The guy I may get getting this from doesn't have the manual or know where to get one.
Probably not interested in turning it into an Aleph. At 30-watts or so its too little power to be a main amp and too much to be a bi-amp tweeter amp.... although... could be an excuse to make the next speakers hi efficiency horns.
The Audio Amateur article (thanks Walter) is almost a complete replacement reusing the power supply and chassis. It's basically a new amp when you're done. (I do have some unpopulated A75 PCB's laying around, perhaps an A75-lite?)
Is there something less drastic you could do, other than replacing the now old electrolytics caps?
(Have soldering skills, not design skills, yet)
Still haven't found a service manual for this yet. The guy I may get getting this from doesn't have the manual or know where to get one.
Probably not interested in turning it into an Aleph. At 30-watts or so its too little power to be a main amp and too much to be a bi-amp tweeter amp.... although... could be an excuse to make the next speakers hi efficiency horns.
I had 3 fortè audio 1a, and I think i'll have in pdf format instructions, list of components used and the schematic.
Nelson may have some tips but it appears to be a completely direct coupled design.Other than checking for proper bias levels and DC offset issues,the filter caps and maybe bridge rectifiers might be all you need to be concerned with due to their age.