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I have Paramours (originals) with a little bit of hum. If I decide to do it, what problem would I have in making a regulated DC supply for the heaters? That assumes the hum is from the heaters.Would having DC heaters on the drivers make any difference? The drivers are 76s.
Remember, YOU are the only one who needs to be happy with the sound of your system
Grainger Morrison
There Is Only One (Grainger Morrison, it seems)
Edits: 09/21/09Follow Ups:
My hum is minuscule. I only hear it with no music playing, not in low passages. But I kind of got the idea from the Paramounts' DC heaters.It is the tweaker's itch and I could put in a new DPDT power switch that also turns on an outboard heater supply.
I know, it is a sickness.
Remember, YOU are the only one who needs to be happy with the sound of your system
Grainger Morrison
There Is Only One (Grainger Morrison, it seems)
Edits: 09/22/09 10/02/09
There are three sources of possible hum in the Paramour circuit:
1) The 2A3 filament. In the Paramount, we use Schottky diodes and a choke filter (no capacitors), plus a filament winding that is shielded from the high voltage windings. The shield plus the leakage inductance of the filter (which is common-mode) protect from common-mode noise. The Paramour II power transformer has a similarly shielded 2.5v winding but is not capable of providing DC power.
2) The power supply. The filter is adequate to reduce hum below the residual filament hum, but if DC filament power is to be used, more capacitance and/or a choke to replace the 270 ohm resistor in the power supply would be needed.
3) The driver may pick up hum from its supply. As long as that supply is grounded, this is not usually a problem with the stock 12AT7, but the 56 and 76 have very little insulation between heater and cathode - it's rated for no more than 45v positive on the heater, and zero negative. So a DC supply here would be potentially useful. The Paramour II power transformer (Bottlehead PT-2) has enough current capacity for such a power supply, but the original Paramour does not.
Unfortunately I don't think there are any PT-2s left in inventory.
Hats off at the attempt for DC heaters. You obviously have some skills as you have already jumped to 76s. I looked into the DC conversion but reviews on SETs w/ DC heaters seemd mixed and it is a big task. People talked about DC heaters having less 'life'... I got down to 0.8 mV hum w/ C4s, 10 turn pots, HV snubber and a couple of ground tweaks (plus meticulous layout). Have fun and write back w/ impressions.
Be advised that many of the VS recs are for the older transformer which is not center tapped and may cause problems if applied to more modern paramours.
Use STP for the filaments and change over to 45's. I forget why, but I have had way better luck getting 45's quiet than 2A3's.
Paul,Thanks for the suggestion. I would love to have a 45 amp but first I have to get speakers that will work on 1WPC. My speakers are 94dBW and are just sensitive enough in my room for my listening preferences.
But I would really like to have a 45 amp! ! ! ! I have liked all that I have heard. They are really magic sounding.
Remember, YOU are the only one who needs to be happy with the sound of your system
Grainger Morrison
There Is Only One (Grainger Morrison, it seems)
Edits: 09/22/09
I put resistors coming off each side of the 2a3 (and then 45) humpots as on VS' site and lost all hum. I also did some of his tricks to get rid of interwinding capacitance to the driver filaments (more of a buzz), and finally went with a dedicated filament tranny for the drivers. I did not go to DC fils on the 'mour drivers and was happy with them.
Maybe not the answer you were looking for.
Triamp... Take a load off!
Thanks, I will look at the site. I bookmarked it a long time ago but haven't looked at his Paramour information.
Remember, YOU are the only one who needs to be happy with the sound of your system
Grainger Morrison
There Is Only One (Grainger Morrison, it seems)
Edits: 10/02/09
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