johnsonad
New member
Im running out of potential areas to upgrade my Paramounts and would like to bounce a few thoughts off the forum. These have been brought up a few times in the archives and from the limited posting seem to make improvements but that is all subjective right!
There are three areas I would like to brainstorm over to include film caps and inductors in the power supply, a DC heater supply for the 5670 driver and a shunting switch or relay for the output transformer to prevent magnetization on start up.
First off, Im a hobbyist with limited skills in development of circuits and the implementation of them. Now that thats out of the way
1. Film caps and inductors in the power supply:
The CRC supply currently used could be changed to a CLC. Myself and a few others have replaced the 270 Ohm resistor with the Triad C-7X choke with good results. On my amps the choke is mounted behind the PS transformer. There is no additional noise that I can here with 100 dB speakers. This is a decent location but as Paul has stated before, it was originally designed to go where the present OPT is when it was configured as the Paradox before becoming the Paramount. Using a choke the capacitance could be lowered from the present 135uF. We would either need a new PS board or wire it all point to point. I for one would be willing to put in money on a small run of new boards. The film caps present a problem of size (both physical and capacitance) and DC rating. A quick look in the usual places shows Mundorf makes a cap with PC standoffs up to 47uF at 600v DC. They have screw type up to 200uF but rated at 550v DC. DIY HiFi Supply has caps with radial leads up to 70uF rated at 630v. There are more out there but these were a few I could find quickly. Unfortunately my computer OS does not support running the PSUD utility so Im unable to model an ideal supply (nor am I any good at this!). Maybe Paul, Doc, Ed could weigh in on suggesting values to use here? Physical size is the biggest problem. The caps in the LEAST will poke out from the bottom. I for one wouldnt be opposed to make a new deeper base or adding a second base that the first could slip into probably with the same wood to match the top.
2. DC heater supply for the 5670:
I for one love the soft start upgrade and the 5670 tube. Though this may make a negligible improvement, in theory a quite DC supply should improve this stage. Paul wrote that the PT-4 puts out 1.2 amps at 6.3v, plenty enough for a supply. Is it worth the effort in doing so? Location of the circuit seems to be the biggest problem. One could move the OPT topside making room for a wider PS board (this is my plan with a TFA-2004 Jr.). You could also use a second smaller board on standoffs below the new PS boards though it would make sense to keep all of the PS components on one board. Practically you could move the Parafeed choke topside too and orient it like the Paradox opening up even more room below.
3. Though not a big problem, it would be nice to get rid of the magnetization of the OPT on start up. As Xavier put it, this clears up after one record side. Paul has commented on shunting the OPT until the circuit is fully powered up. Not sure how to do this. Could use a relay or a switch it would seem. Either way there would be full voltage on it and this could be dangerous considering the limited benefit. Thoughts?
Again this is an effort in brainstorming and potentially design. We all love our Paramounts and like most things in this hobby we tweak it until perfected (at least in our own minds!). These may not be practical given the limited space but all of these upgrades have potential for benefit.
Aaron
(edited for brain farts
There are three areas I would like to brainstorm over to include film caps and inductors in the power supply, a DC heater supply for the 5670 driver and a shunting switch or relay for the output transformer to prevent magnetization on start up.
First off, Im a hobbyist with limited skills in development of circuits and the implementation of them. Now that thats out of the way
1. Film caps and inductors in the power supply:
The CRC supply currently used could be changed to a CLC. Myself and a few others have replaced the 270 Ohm resistor with the Triad C-7X choke with good results. On my amps the choke is mounted behind the PS transformer. There is no additional noise that I can here with 100 dB speakers. This is a decent location but as Paul has stated before, it was originally designed to go where the present OPT is when it was configured as the Paradox before becoming the Paramount. Using a choke the capacitance could be lowered from the present 135uF. We would either need a new PS board or wire it all point to point. I for one would be willing to put in money on a small run of new boards. The film caps present a problem of size (both physical and capacitance) and DC rating. A quick look in the usual places shows Mundorf makes a cap with PC standoffs up to 47uF at 600v DC. They have screw type up to 200uF but rated at 550v DC. DIY HiFi Supply has caps with radial leads up to 70uF rated at 630v. There are more out there but these were a few I could find quickly. Unfortunately my computer OS does not support running the PSUD utility so Im unable to model an ideal supply (nor am I any good at this!). Maybe Paul, Doc, Ed could weigh in on suggesting values to use here? Physical size is the biggest problem. The caps in the LEAST will poke out from the bottom. I for one wouldnt be opposed to make a new deeper base or adding a second base that the first could slip into probably with the same wood to match the top.
2. DC heater supply for the 5670:
I for one love the soft start upgrade and the 5670 tube. Though this may make a negligible improvement, in theory a quite DC supply should improve this stage. Paul wrote that the PT-4 puts out 1.2 amps at 6.3v, plenty enough for a supply. Is it worth the effort in doing so? Location of the circuit seems to be the biggest problem. One could move the OPT topside making room for a wider PS board (this is my plan with a TFA-2004 Jr.). You could also use a second smaller board on standoffs below the new PS boards though it would make sense to keep all of the PS components on one board. Practically you could move the Parafeed choke topside too and orient it like the Paradox opening up even more room below.
3. Though not a big problem, it would be nice to get rid of the magnetization of the OPT on start up. As Xavier put it, this clears up after one record side. Paul has commented on shunting the OPT until the circuit is fully powered up. Not sure how to do this. Could use a relay or a switch it would seem. Either way there would be full voltage on it and this could be dangerous considering the limited benefit. Thoughts?
Again this is an effort in brainstorming and potentially design. We all love our Paramounts and like most things in this hobby we tweak it until perfected (at least in our own minds!). These may not be practical given the limited space but all of these upgrades have potential for benefit.
Aaron
(edited for brain farts
