Hi,
I would like to build a simple and cheap tube amp with the schematic below.
There will be one pcb to manage the feedback, but that will come later.
I would like to keep this part of the circuit as simple as possible, on turret or even point-to-point.
Power supply will be one single secondary going to a first 220u 550V common capacitor, then 22 Ohm to 220 Ohm for each channel.
Output transformer screens are supplier through UL connections, LTPI anodes are supplied through KT88 plates using a positive feedback connection to have better sensitivity.
A specific negative feedback circuit will manage distortion and Zout of the amp.
Negative rail will be for bias and for LTPI cathode's CCS.
Transformers are toroidal, and I want to keep them "under the bonnet", with a flat surface on top.
There will be two channels on one single stereo amp.
Thank you for the suggestion.
I would like to build a simple and cheap tube amp with the schematic below.
There will be one pcb to manage the feedback, but that will come later.
I would like to keep this part of the circuit as simple as possible, on turret or even point-to-point.
Power supply will be one single secondary going to a first 220u 550V common capacitor, then 22 Ohm to 220 Ohm for each channel.
Output transformer screens are supplier through UL connections, LTPI anodes are supplied through KT88 plates using a positive feedback connection to have better sensitivity.
A specific negative feedback circuit will manage distortion and Zout of the amp.
Negative rail will be for bias and for LTPI cathode's CCS.
Transformers are toroidal, and I want to keep them "under the bonnet", with a flat surface on top.
There will be two channels on one single stereo amp.
Thank you for the suggestion.
From what I know toroid's do not make good OPT's. That said I have a pair of brand new Heyboer Z out 6600 opt transformers I no longer need. PM me if you are interested?
Then I guess you have not seen/used Toroidy transformers.
I have used and tested many with very good results.
Toroidy are some of the few good toroidal output transformers. I also use Hayboer for my outputs and Antek for the power Tx. If you are doing solid state rectification and don’t need a 5v winding then go with Antek as they are well made and not expensive for the quality.
Do you have a liost of Toroidy part numbers? I acquired a 35w PP amp with a pair of toroidal OPTS but the only marking on them is ZD043 dated 1997.
They are about the size of a 300va mains transformer.
The design was by Claus Byrith and used a pair of EL34, with 450v B+.
Toroidy even has Single Ended toroidal OPT's. I have used them. They work and sound far better than those huge Hammond 1628SEAs that they replaced.
I confess I have no personal experience with toroidal OPT's. I have used many Antek power transformers and I love those. I've been away from amp building for a while. I remember an article about a Japanese builder who used toroid's in an 8B clone and I looked into those but they were more expensive than Heyboer. In the end I used a pair of Vintage ST70 Dynaco outputs for my 8B clone. I compared it with an actual 8b. The owner of the 8b was really impressed. The clone had better bottom but the real 8b was better in the midrange and high frequencies. But the difference was only just noticeable.
The prices seem to be more affordable than Hammonds. I wish I'd known about them last week as I've just bought a pair of OED (British) OPTs which are similar size, 90% of the price and spec to the 1640 for a PSE amp with high voltage op amp for the Vas/input stage.