I'm very pleased with the preamp and phase inverter section of my re-built 6V6 mystery amp. In a further post we discuss cabinet options Use a half of a 12AX7 to act as tremolo oscillator and the other half to amplify the reverb pan output. If you like to have also tremolo, look at this diagram. Place a potentiometer after the mentioned recovery preamp, lift the 100nF condenser (at pin 7) from ground and connect it to the pot slider. If you wish to include a reverb you can drive its input (attenuated with a suitable resistor ! ) directly from the secondary of the output transformer.įrom the output of the reverb tank build any kind of reverb preamp using tubes op amps or transistors, and send its output to pin 7 of the second 12AX7 Replace the rectifier tube with a couple (or diode bridge if the power transformer does not have center tap) of 1N4007 and increase the size of filter caps to your taste. Leave those taps floating and connect the screen grids as pentode with suitable resistors.Īnswer 3 and 4: Look at the following diagram: I'm not exactly an tube guru but an authentic tube enthusiast, so there are my opinion:Īnswer 1: Transformer P4131 looks OK to be used in a guitar amp project as the frequency range is lower compared to hi-fi and the core size must be enough (IMHO)Īnswer 2: Yes. What are your thoughts and criticisms please?ĭon’t expect to see results immediately as I have a ton of unfinished projects but if I get fired up it may happen sooner rather than later. Possibly tremolo and/or spring line reverbĬab and chassis design open to suggestion Hopefully EL84 output valves (as I have quite a few) Some mild OD without the use of pedals, possibly foot switch controlled I’m thinking of building something along the lines of an AC15 / Marshall 18W / Fender blues Junior for use when playing slide guitar (acoustic guitar with piezo under the saddle and basic high impedance buffer). Would you recommend a single or double valve Phase Inverter (can’t remember the proper names for them). As as far as I can remember none of the guitar amps I have worked on have used screen grid taps, should I just ignore these and use screen grid resistors? The Mullard Circuits For Audio Amplifiers book shows the P4133 used with 2x ECL84 (for 8W) and the P4131 with 2x EL84 (for 10W) but these are intended for Hi-fi use so probably not that relevant. Would the P4133 be ok to use with a pair of EL84s or 6V6s? I also have a couple of suitable looking mains transformers (250v 60mA + 6.3v 3A and 260 – 0 – 260v current unspecified with 6.3v 2.5A), a Celestion green back, a spring line reverb unit and a load of suitable plywood and sheet metal so I thought why not? I recently discovered I had an old push pull output transformer (marked P4133, possibly an early Partridge P4133, probably late 50's or early 60's). I’ve been fixing valve gear since before solid state was available (mid 60’s) and have built a load of SS amps and even one class D but never a valve amp. I need a bit of advice and guidance from the valve (tube) gurus.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |