How to decrease noise in Paramour I?

[Jon L]

My Paramour I has always had a little bit of hum and hiss through my 95dB sensitive speakers, but not enough to bother me.

However, I've been using them to power a Stax transformer box to run electrostat headphones, and the hum/hiss is VERY audible this way.  Same thing running AkG K1000 earspeakers. 

Am I pretty much stuck with this situation or is there a way to decrease the noise?  I didn't build these myself, but should I mess around with that little knob underneath (humpot?)?

 

[Doc B]

The hum balance pot can minimize the hum, but there will always be some hum through headphones, since the Paramour uses an  AC filament supply - it was not conceived for headphone use. The Paramounts have a DC filament supply and are quiet enough for this kind of application. They also sound great with AKG K1000s.

To balance the hum connect a DMM to the speaker binding posts and set the meter to the lowest AC volts scale. Adjust the hum pot for the lowest meter reading, which will typically be around 2 or 3mV depending upon the tubes used.

 

[ssssly]

Check out voltsecond's web site. Lots of good Paramour I stuff. Don't know if it will get it quiet enough to get rid of hum in headphones but definitely good stuff.

 

[Paul Joppa]

Just a quick check - do your Paramours have the C4S upgrade on the driver? It's a small circuit board, like a large postage stamp, sort of floating in midair near the driver tube socket. If not, that upgrade will reduce hum quite a bit. (It also sounds better!)

 

[Grainger49]

Jon, you have a PM.

 

[Jon L]

Just a quick check - do your Paramours have the C4S upgrade on the driver? It's a small circuit board, like a large postage stamp, sort of floating in midair near the driver tube socket. If not, that upgrade will reduce hum quite a bit. (It also sounds better!)

Yes, it's got the C4S upgrade but stock irons.  Tubes are all fresh and the hum is the same on Left and Right. 

Well, this might give me incentive to hunt out some Paramounts, I guess, but I love my EML 2A3 solid plates, and the Paramounts are supposed to shorten their life

 

[Paul Joppa]

We hope to have a slow-turn-on modification for Paramounts in a few weeks, which (again, I hope!) will let them use the EMLs. I have some other plans as well, for later in the year, that could result in a new Paramour power supply with DC filament power.

The hiss problem strikes me as rather odd, however. In a low-gain power amp, I would not normally expect it to be audible, especially on average or low-sensitivity headphones. That leads me to wonder whether it might be upstream from the power amps. Can you install shorting RCA plugs in the Paramours and listen for hum and noise? If you still hear it, is it tilted to the treble (sibilant) or bass (more of a rushing sound)? If you have an FM tuner, the interstation hiss is a reliable reference for a random noise spectrum; it's Gaussian (hissy) up to about 2kHz, then more of a rush in the treble.

 

[ssssly]

Paul,

Put me on the list for the first batch of the shunt regs with the slow turn on.

Is the final piece of my Paramour upgrade project.

Will the new power transformers have the same relative footprint as the PT-2?