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First of all, a dutiful disclaimer: the writer has been passionate about electronics and guitar pedals for a very short time, so I ask you to forgive any stupid or meaningless questions dictated by the few acquaintances gained so far.
So, I recently built a Deacy Amp following the Paul Stevenson / Greg Fryer layout and scheme. By Fryer's own admission that version of the Deacy was very similar to the original, but not 100%. Further studies therefore followed, but concentrated mainly on the loudspeaker used which led to a result such as to produce and sell the product obtained as a replica.
The scheme on which this amplifier was based was practically the one present in the Mullard Reference Manual for Transistor (page 171) but, as it turned out later, the original circuit diagram recovered in a skip by bassist John Deacon belonged to a portable radio from 1965 produced in South Rhodesia called Supersonic PR80.
The diagram of the amplification section of that radio is in fact practically identical to that present in the Mullard manual, but not perfectly identical (it should be noted that unlike those indicated in the manual, the Fryer layout uses transistors AC125, 126 and 128).
From what I seemed to understand, much of the accuracy of the sound is given by the two transformers present in both circuits but, around those of the PR80 there is a sort of mystery which seems rather difficult to solve.
Now, given that: finding a PR80 seems like an impossible feat (I tried asking a group of vintage radio enthusiasts here in Italy and was offended by my intentions to dissect it and turn it into a guitar amplifier: D), the price proposed by the only manufacturer who has managed to put his hand on that circuit is absolutely exaggerated for my pockets (€ 300 only for the complete pcb) I ask you if it is somehow possible to modify the Stevenson / Fryer layout to make it more similar to the , let's call it PR80, without having to replace the two transformers.
Finally, a question regarding the amp I just finished: what makes it dissimilar to the original is the lack of that "fizz" that makes it so distinctive (as well as a slightly less muffled sound). Could this lack be caused by transistors that do not have sufficient hfe?
I thank all those who want to participate in this discussion.
I attach photos and links of the various layouts and schemes:
Stevenson / Fryer Layout: https://paulinthelab.blogspot.com/20...tripboard.html
Stevenson / Fryer Schematic: https://2.bp.blogspot.com/-CIf5yPKau...1600/deacy.bmp
Supersonic PR80 Schematic: https://i.pinimg.com/originals/67/68...ca90c2e630.jpg
So, I recently built a Deacy Amp following the Paul Stevenson / Greg Fryer layout and scheme. By Fryer's own admission that version of the Deacy was very similar to the original, but not 100%. Further studies therefore followed, but concentrated mainly on the loudspeaker used which led to a result such as to produce and sell the product obtained as a replica.
The scheme on which this amplifier was based was practically the one present in the Mullard Reference Manual for Transistor (page 171) but, as it turned out later, the original circuit diagram recovered in a skip by bassist John Deacon belonged to a portable radio from 1965 produced in South Rhodesia called Supersonic PR80.
The diagram of the amplification section of that radio is in fact practically identical to that present in the Mullard manual, but not perfectly identical (it should be noted that unlike those indicated in the manual, the Fryer layout uses transistors AC125, 126 and 128).
From what I seemed to understand, much of the accuracy of the sound is given by the two transformers present in both circuits but, around those of the PR80 there is a sort of mystery which seems rather difficult to solve.
Now, given that: finding a PR80 seems like an impossible feat (I tried asking a group of vintage radio enthusiasts here in Italy and was offended by my intentions to dissect it and turn it into a guitar amplifier: D), the price proposed by the only manufacturer who has managed to put his hand on that circuit is absolutely exaggerated for my pockets (€ 300 only for the complete pcb) I ask you if it is somehow possible to modify the Stevenson / Fryer layout to make it more similar to the , let's call it PR80, without having to replace the two transformers.
Finally, a question regarding the amp I just finished: what makes it dissimilar to the original is the lack of that "fizz" that makes it so distinctive (as well as a slightly less muffled sound). Could this lack be caused by transistors that do not have sufficient hfe?
I thank all those who want to participate in this discussion.
I attach photos and links of the various layouts and schemes:
Stevenson / Fryer Layout: https://paulinthelab.blogspot.com/20...tripboard.html
Stevenson / Fryer Schematic: https://2.bp.blogspot.com/-CIf5yPKau...1600/deacy.bmp
Supersonic PR80 Schematic: https://i.pinimg.com/originals/67/68...ca90c2e630.jpg
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