We have schematics for the M-50 and MP-1, Will.
You asked for a schematic, not internal layouts. We don't have a schematic that is all that neat as I mentioned before. But apparently even if I had provided it, that would not have solved the problem, which is you also want the layout.
I did point out to you on the phone that we use several terminal strips, the largest being a 3-place terminal.
You told me that you have one of the blue units, which is from the first run of 10, nine of which are hand wired, and 3 of which had the phono circuit. We don't have any of those on hand (only a few were built that way) as a reference; all the units we have on hand employ the circuit board.
Since the circuit is simple, and I have laid out its characteristics, it follows that it will be easy to service in the event that we go out of business. All of our equipment was built to be serviced; I put myself through college by servicing consumer gear and got quite tired of fixing equipment that was clearly not intended to be serviced after the sale.
So here is what I can tell you about the layout, which is from memory as we don't have internal photos of the handwired units. The 3 position terminal is located to the front of the unit, where the output coupling caps are located. The inputs were thus towards the rear, and tied directly in to the phono so that only the output is switched; and is adjacent to the input selector switch. The chassis is equipped with pressed through studs for mounting the tube sockets (this was done to minimize visible hardware on the outside of the unit). There are extra pressed through studs that aren't used for the tube sockets.
They are meant for terminal strips. Unlike some companies, we don't use hot melt glue to hold things in place. We use Keystone terminal strips as they are accessible and easy to get. The Keystone part numbers used are #810 for the 2-position strips used on either side of the sockets, and #813 for the 3-position parts which are mounted on the studs not associated with the tube sockets. They and the tube sockets are secured by 4-40 KEPS nuts (KEPS nuts have a captured lockwasher). I was attempting to tell you this information at the end of our phone call. If you'd stayed on the phone longer I would have told you more, and still will if you care to pursue this project.
One thing I forgot, we use stopping resistors in series with the grids of each stage. The value is 300 ohms. This allows the phono section to be stable and so reduces ticks and pops that would otherwise become audible due to short-term oscillation. This is why you will hear more ticks and pops on a PAS-3 (they missed the second stage of gain) than you will on the UV-1.
Regarding the power supply: you should have at least three filter caps in your line stage at present- two 33uf parts and one 100uf part. For the phono section, two 22uf caps are added, one for each channel. So there are two resistors of 22.1K that feed those 22uf units from the 100uf unit. Both stages of the phono run off of the 22uf part.
We never generated layouts for the initial run; what you may not know is that the preamp was originally commissioned by a third party, and we were uncertain at the time where exactly the project would go. When that party backed out of the project, we already had the first 10 chassis sitting on a shelf, where they sat for a couple of years until we realized that there actually was a market for the preamp and so we built some up. We did try to keep all the handwired units looking the same internally but as there were only three built with the phono and since it is a fairly simple circuit, no-one here thought to document the layout, since the intention all along was to put the whole thing on a circuit board.
I'm sorry this has caused you such distress; we do support our products to the best of our ability.
You asked for a schematic, not internal layouts. We don't have a schematic that is all that neat as I mentioned before. But apparently even if I had provided it, that would not have solved the problem, which is you also want the layout.
I did point out to you on the phone that we use several terminal strips, the largest being a 3-place terminal.
You told me that you have one of the blue units, which is from the first run of 10, nine of which are hand wired, and 3 of which had the phono circuit. We don't have any of those on hand (only a few were built that way) as a reference; all the units we have on hand employ the circuit board.
Since the circuit is simple, and I have laid out its characteristics, it follows that it will be easy to service in the event that we go out of business. All of our equipment was built to be serviced; I put myself through college by servicing consumer gear and got quite tired of fixing equipment that was clearly not intended to be serviced after the sale.
So here is what I can tell you about the layout, which is from memory as we don't have internal photos of the handwired units. The 3 position terminal is located to the front of the unit, where the output coupling caps are located. The inputs were thus towards the rear, and tied directly in to the phono so that only the output is switched; and is adjacent to the input selector switch. The chassis is equipped with pressed through studs for mounting the tube sockets (this was done to minimize visible hardware on the outside of the unit). There are extra pressed through studs that aren't used for the tube sockets.
They are meant for terminal strips. Unlike some companies, we don't use hot melt glue to hold things in place. We use Keystone terminal strips as they are accessible and easy to get. The Keystone part numbers used are #810 for the 2-position strips used on either side of the sockets, and #813 for the 3-position parts which are mounted on the studs not associated with the tube sockets. They and the tube sockets are secured by 4-40 KEPS nuts (KEPS nuts have a captured lockwasher). I was attempting to tell you this information at the end of our phone call. If you'd stayed on the phone longer I would have told you more, and still will if you care to pursue this project.
One thing I forgot, we use stopping resistors in series with the grids of each stage. The value is 300 ohms. This allows the phono section to be stable and so reduces ticks and pops that would otherwise become audible due to short-term oscillation. This is why you will hear more ticks and pops on a PAS-3 (they missed the second stage of gain) than you will on the UV-1.
Regarding the power supply: you should have at least three filter caps in your line stage at present- two 33uf parts and one 100uf part. For the phono section, two 22uf caps are added, one for each channel. So there are two resistors of 22.1K that feed those 22uf units from the 100uf unit. Both stages of the phono run off of the 22uf part.
We never generated layouts for the initial run; what you may not know is that the preamp was originally commissioned by a third party, and we were uncertain at the time where exactly the project would go. When that party backed out of the project, we already had the first 10 chassis sitting on a shelf, where they sat for a couple of years until we realized that there actually was a market for the preamp and so we built some up. We did try to keep all the handwired units looking the same internally but as there were only three built with the phono and since it is a fairly simple circuit, no-one here thought to document the layout, since the intention all along was to put the whole thing on a circuit board.
I'm sorry this has caused you such distress; we do support our products to the best of our ability.