Paramount with Soft Start Sound?

[stevesong]

Hi,
I am a newbee on Bottlehead forum and I came across 2 pairs of Paramounts.
One with Soft Start Kit installed and another without the Soft Start Kit but with some upgrades (All Nickle Magnaquest transformers, Mundorf Silver/Oil caps, upgrated connectors.

Paramounts without the Soft Start Kit sounds more dynamic and silky, but with a little more pronounced upper midrange and treble.  Since my speakers are already bright sounding, I would like to have the frequency balance of the Paramounts with the Soft Start Kit.

Can anyone guess what can be done to make them sound more relexed in the highs?
I was considering it may be due to the following:

12AT7 tubes (Telefunken, Mullard, EH, Amperex 7062) vs Soft Start Kit 5670 (GE 5 star),
or Mundorf Silver/Oil,
or Magnaquest Transformers.

I know I have to try to be sure, but if anyone can guess right it will save me money and time.

[Paul Birkeland]

The actual soft start circuit is intensely unlikely to change the sonic characteristics of the amplifier.

The 5670 vs. 12AT7 tube difference between the two will contribute to sonic differences, as would the Magnequest vs. stock iron, and the coupling caps.

The least expensive place to start would be to do the soft start conversion to your amps, then play with different caps, then change over the output transformers. 

[stevesong]

Thanks for your advise I was hoping not the soft start kit
It should be the least expensive one to consider, but involves soldering skills which is not my specialty.

Would anyone guess differences between Mundorf silver/oil (6.8 uf) vs stock Solen caps?

[Grainger49]

First, WOW 2 pair of Paramounts to play with, that is the luck of the Irish!

Let's try some things that are free.  First, swap the output tubes from one pair of amps to the other.  As Paul B above says the driver tubes are not the same and can't be swapped.

If both are 300B versions and have different interstage caps, stock is 0.1uF (I think brown film) caps, you can swap them.

If the Parafeed caps are close to the same value, the MQ iron may need a different value, then swap these. 

This will get you off to a cheap start, only time invested.

[stevesong]

In Fact, my friend, after listening to the pair with soft start kit, liked it so much and I sold this pair to him.

I had both pairs for about a week and switched output tubes (but not the driver tubes as you indicated) finding the same.
Both pairs are 300B versions and both have the same interstage caps (Russian Teflon).

The pair with soft start kit has Parafeed cap value of about 3.5uf.
6.8uf on the pair with MQ iron.

[Grainger49]

So the differences in the audio path are the driver tubes, the iron and Parafeed caps.  As PB mentions the soft start is not in the audio path.  But the Soft Start board allows tweaking of the bias on the driver.  That might make a difference with the 5670.  It might not, but it might.

[Doc B.]

It's the 5670 that makes the difference.

[stevesong]

Thanks!

I should try the softstart kit.
Will post the results here after installation and audition.