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Author Topic: Some updates to my odd ball Paramounts  (Read 305 times)

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Offline johnsonad

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Some updates to my odd ball Paramounts
« on: January 14, 2021, 09:45:35 AM »
This week I made some much needed updates to my Paramount-ish amps.  There is a thread on their build somewhere on the archives.

These amps were originally designed to add a much larger footprint for experimentation.  They were built before the Kaiju was released which addressed the minimal shortcomings of the original Paramounts. The operating point is different, 350v P-K, -76v, 50mA, 5k.  To lower the voltage of the power transformer two PC-2 plate chokes were used in the power supply.  The parafeed choke is from Magnequest gapped for 50mA and the output transformers started with MQ EXO-050’s with full nickel.  A couple of years later I added TL-404 XL’s with a couple of switches to go between these two OPT’s.  To play around with drivers, I split the shunt regulator tube to an additional 9 pin and an 8 pin socket.  This allowed me to use a 5670 for the shunt reg side and play around with tubes for the driver.  I tried 6J5 and variants and 7A4 locktels with a tube converter.  It was a lot of fun exploring what was out there.

Fast forward another three or so years and my system has had a few changes.  The Altec 19’s were replaced by Altec 755A’s in WE cabs and Rythmik subs.  I use the HPF in the subs to feed 80Hz and above to the Altecs.  With no crossover, these little drivers show any changes you make. After the speaker swap, the 050’s in nickel were just too much for me.  It’s hard to describe but in the end, I couldn’t listen to them for long lengths of time and spent most of the time listening to the 404’s.

 I made a fortunate trade and ended up with a pair of pinstripe EXO-050’s.  These were swapped with the full nickel and from the first record played I was happy.  Compared against the 404’s, the pinstripe’s were significantly better in this amp.  PB attributed it to increased magnetic headroom.  Whatever it was, the improvement was what I was looking for.  The 404’s were removed along with the switches and these amps are finally where I want them.  For drivers, after all of that tube rolling, I couldn’t find one that beats the GE 5670 in my system.     

I included a few before and after photos.  I’ve seen a few people struggle with large caps in their build.  I added a photo of my work around.  Just put a standoff in with a cable holder and zip tie the cap to the cable holder. 
Aaron Johnson

Offline Doc B.

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Re: Some updates to my odd ball Paramounts
« Reply #1 on: January 14, 2021, 11:19:22 AM »
TL404s were intended for a lot less power than a 300B makes. Mike sent me a pair from the first run he made and I think I recall him saying a couple watts was the sweet spot. Not surprised a pinstripe EXO-050 sounds better in this application than all permalloy cores for the same reason. We were always pushing MQ iron a bit past Mike's comfort zone when we used it in our circuits.

That said, I think I am just as happy with our own iron in our amps these days. There is something to be said for having control over the design of the magnetic components as well as the circuit. Makes it easier to get to the desired end result.
Dan "Doc B." Schmalle
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Offline Deke609

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Re: Some updates to my odd ball Paramounts
« Reply #2 on: January 14, 2021, 11:26:42 AM »
These amps were originally designed to add a much larger footprint for experimentation.  They were built before the Kaiju was released which addressed the minimal shortcomings of the original Paramounts. The operating point is different, 350v P-K, -76v, 50mA, 5k.  To lower the voltage of the power transformer two PC-2 plate chokes were used in the power supply.  The parafeed choke is from Magnequest gapped for 50mA and the output transformers started with MQ EXO-050’s with full nickel.  A couple of years later I added TL-404 XL’s with a couple of switches to go between these two OPT’s.  To play around with drivers, I split the shunt regulator tube to an additional 9 pin and an 8 pin socket.  This allowed me to use a 5670 for the shunt reg side and play around with tubes for the driver.  I tried 6J5 and variants and 7A4 locktels with a tube converter.  It was a lot of fun exploring what was out there.

Two words: PURE AWESOMENESS

I've been playing with the idea of doing a similar 5670 reg setup in a scratch amp build (likely with EML 45B as power tube) - just using one 5670, with each channel's Kaiju-inspited shunt reg using one side of the tube. 

cheers, Derek
Derek
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Roon Intel NUC ->  Yggdrasil DAC -> BeePre (w/ BeeQuiet and EML 300B)  -> Kaiju (w/ DCFil and EML 300B) or Stereomour II (2A3 [EML Mesh] and 45 Conversion [EML 45B])  -> Audeze LCD4

Offline johnsonad

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Re: Some updates to my odd ball Paramounts
« Reply #3 on: January 14, 2021, 11:36:49 AM »
The 404 XL’s were said to be good for 5 watts. Still, under rated for this job though I was only using them for 80 Hz and up. I’ve been looking for 050’s in standard lams for years. Sadly they don’t come up often and for good reason. The pinstripe sound great but I still want to try a m3/m4/m6 at some point.

I agree DocB. Your new iron is superb. I like it more than the MQ stuff now. If these pinstripes didn’t come along I was considering changing the operating point and putting Kaiju iron in it. You all really hit the mark with the Kaiju.

Derek, give it a go and share your build. It sounds like a cool project.
« Last Edit: January 14, 2021, 11:55:16 AM by johnsonad »
Aaron Johnson

Offline Gerry E.

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Re: Some updates to my odd ball Paramounts
« Reply #4 on: January 15, 2021, 11:13:37 AM »
Hi Aaron:

It's good to see that I'm not the only one trying to squeeze that last bit of juice out of Paramount/Paramount-ish amps!  You have gone way beyond me but I just had a friend install a pair of upgraded parafeed caps (see photo below).  Maybe these are overkill but I got them for a really good price.

Not to hijack your thread but I have a question.  The new caps are HUGE (the photos don't do the size justice).  My friend didn't want them dangling free, so he attached them to the plate choke with some silicone.  Does anyone think this is a problem?  I'm not sure if plate chokes generate any heat and/or vibration.  I listened to them for about an hour or so today and didn't hear any problems.  Thanks!

Gerry

Offline johnsonad

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Re: Some updates to my odd ball Paramounts
« Reply #5 on: January 15, 2021, 11:30:23 AM »
That shouldn’t be an issue Gerry. Damm those are some big caps!
Aaron Johnson

Offline Paul Birkeland

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Re: Some updates to my odd ball Paramounts
« Reply #6 on: January 15, 2021, 11:36:19 AM »
Gluing the cap to the plate choke is OK.  Bathroom/window/kitchen silicone is corrosive and will attack copper, so I suggest using black RTV in the future for that purpose.

-PB
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Gerry E.

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Re: Some updates to my odd ball Paramounts
« Reply #7 on: February 22, 2021, 05:22:26 AM »
Gluing the cap to the plate choke is OK.  Bathroom/window/kitchen silicone is corrosive and will attack copper, so I suggest using black RTV in the future for that purpose.

-PB

Thanks PB and Aaron!  Here's an update of my experience with the Jupiter Copper Foil caps and another question.  The caps are super smooth sounding in the good sense of the word.  The other improvement is in the sound-stage.  Before changing caps, the sound-stage was strong in the center and far left/far right.  The new caps seemed to have strengthened the images in-between.  Overall, I would not call it a night and day difference but given the cost of the caps and the total cost of my system, it was a worthwhile exercise.

Question - I haven't had much luck in selling the replaced Mundorf 3.3uF Silver/Oil caps, so I have been wondering, space issues aside, if I could add them in parallel to the Jupiter caps?  This would put the total capacitance at 8uF, well within the 6 - 12uF range as suggested by PJ when using the upgraded MQ iron.  My concern is will the addition of the Mundorf caps somehow change the sound quality I'm hearing from the Jupiter caps?  IOWs, has anyone tried paralleling different brands of caps in a significant cap position and what were the results?  I assume this is a different situation than just adding a .01uF bypass cap.  Thanks!

Gerry                 
« Last Edit: February 22, 2021, 05:36:34 AM by Gerry E. »

Offline Paul Birkeland

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Re: Some updates to my odd ball Paramounts
« Reply #8 on: February 22, 2021, 05:38:46 AM »
Temporarily solder them in and have a listen!
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline johnsonad

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Re: Some updates to my odd ball Paramounts
« Reply #9 on: February 22, 2021, 06:51:40 AM »
Or put them on alligator clips. I did a lot of cap rolling that way in the first BeePre.

Thanks for the review of the Jupiters. I’ve been considering a pair for the BeePre2.
Aaron Johnson