I've been doing a bit of research , cross referencing between different builds and I see that some use Tantalum Caps and Polystyrene (EZ1290) and the proaudiogc doesn't. I've seen the same happening between the EZ1073 500 and the DIYRE version .
I'm still a beginner in many ways so I'm trying to make sense of what's the most "authentic" to the original design. Are those designer choices or a variation on the circuit?
When looking for "authentic," which model and serial number are you making reference? Component value tolerances were much higher than now, so two brand new units could sound very different. I have found that trying to build a vintage circuit
exactly like an "original" (see above) to be a fool's errand. If you build a 1073/1290 style circuit with quality components and bias it for symmetrical clipping, you will have a great sounding circuit.
I have completed numerous build using BA283 type amp blocks and my recommendations are the following:
- Use WIMA radial caps instead of polystyrene. I have build them with both and without some sort of forensic examination, I cannot tell the difference. I will say that unless your board is laid out for axial polystryene capacitors, it will require you to get creative dealing with placement while stuffing boards designed for radial caps. And if you are newer to DIY you might destroy them in process by overheating them.
- Unless you have a specific, trusted distributor who tests NOS transistors, Use MPS18 and place them backwards in relation to the silkscreen on the board. I used to seek out older active components for building vintage designs but after getting a batch of bad transistors to build a stereo ADR Compex 760, I said never again. It was already a troubleshooting PhD thesis and then having to disassemble it several times before finding out that dozens of the NOS batch of transistors were bad. You have been warned.
- Transformers will make a difference. I have had great results with Carnhill, Ed Anderson, and AMI. Currently all of my new builds use AMI.
Thanks!
Paul