[drummerwill]

 I don't know about you guys but I just can't stop building stuff..   
 
  While waiting for a steel chassis to rebuild my 6SN7 DC 45 IT 845 Low power amp. I
was thinking .... It would be nice if I changed it to a DHT front end, like a Type 26 .

  So to see what a type 26 driving a 45 would sound like I wiped together this little
   amp  to hear...... Well it only puts out about i/2 watt per channel and when I use a passive
   preamp I have to crank the source and the amp volume all the way max to get loud
   music from my GPA 604 III's in MTLT's.

    But its a sweet captivating sound ........ But not for Rock n Roll !
         (Gotta finger out how to post pics with this system )

    Have fun
   Willie

[daves]

Willie, does replacing the 2a3s count as DIY?

[MerRev]

Good to hear you're still at it Willie.     It's hard to walk away from something you enjoy so much.   Have you assembled and new trains recently or PP845's?

                                                                                                    -merrev

[drummerwill]

 Hi Ya Chris

    Naaw .... no more Trains or PP anything.... What I've learned since building the PP 45 Train and the
 other 45/2A3 PP amps, they are just not as challengeing as SET amps.

   I've been learning from 2 guys Jeff Medwin and Dennis Fraker ( of Serious Stereo ), that SET amp sounds are
 more influence by the way they are designed and built than PP.

   The power supply is the key to a great SET, moreso a "Modern Designed" power supply has more influence than the
  type of output tube, as far as sound is concerned..... That coupled with a thoughtfully designed layout of the amp,
  quality wiring and parts, will get you to "World Class " performance.

    So right now I'm waiting on a new 21"X13"X4" steel chassis to start the rebuild of my Low power 6SN7 to 45 to
   845 SET stereo amp.... I think the next 8 to 12 months of my spare time is counted for.

  Sooooo, Thats where I am now,...... trying to spread the word.

   Have fun
   Willie

[drummerwill]

Willie, does replacing the 2a3s count as DIY?

    Sure Dave, ...swapping tubes count !

    Have fun
     Willie

[MerRev]

Glad to hear it Willie!

Good company there with drlowmu and Dennis. 
Back to the ole 845 tube- can't wait to hear it once completed. 
Since your an Altec 604 nut have you ever considered Oris or Azura horns?

merrev

[DaveC113]

   The power supply is the key to a great SET, moreso a "Modern Designed" power supply has more influence than the
  type of output tube, as far as sound is concerned..... That coupled with a thoughtfully designed layout of the amp,
  quality wiring and parts, will get you to "World Class " performance.

Agreed.

Have you tried these PS caps?

https://www.partsconnexion.com/capacitor_film_clarity_tc.html

Very low ESR specs, these will make a massive difference in your PS performance. I just got them for both my SET and my 6SN7 tube preamp. I have a Mundorf M-Tube Cap that is similar to the Clarity caps in the SET amp and the difference between that and an electrolytic was amazing, even though the electrolytic was in parallel with 2 80 uF oil filled motor run caps. The Clarity Caps have about an order of magnitude less ESR than the Mundorf Tube Caps, so I expect it will be even better.

[drummerwill]

 Yeah I was just looking at Clarity caps on a Parts Connextion ad, I did not look see these
  TC series cap..... say you've had good results with them ..eh !...I only hope they're better than
  Solens .............I DO NOT use electrolytics if I have any chioce in the matter.

   Thanks
    Willie

[DaveC113]

Yeah I was just looking at Clarity caps on a Parts Connextion ad, I did not look see these
  TC series cap..... say you've had good results with them ..eh !...I only hope they're better than
  Solens .............I DO NOT use electrolytics if I have any chioce in the matter.

   Thanks
    Willie

I have just used the Mundorf M Tube Cap so far, but I have 3 of the TC series caps at 110 uF sitting on my table for my amp and preamp, and just ordered a 33 uF for the 1st stage of my amp's PS, right after the rectifier tube. The Mundorf made a huge difference in my amp and I'm hoping the TC caps will be even better, the ESR specs are 9 mOhm for the Mundorf and about 1 for the TC cap. They are very large, like motor-run cap size... very expensive, especially since my preamp has separate RC filters for each channel so I needed 2 of them.... but once I heard the difference the Mundorf cap made any thought about them being too expensive didn't matter so much anymore. 

That will rid my preamp off all electrolytics in the signal path, unfortunately my SET amp needs a cathode bypass caps on the power tube's cathodes large enough to be impractical for using film caps, but I found bypassing that with a good film cap has helped immensely. I also ordered 2 of the Clarity Cap ESA series 250V 1.5 uF for new bypasses as I think my current bypass caps are too small at .1 uF and only affecting the upper-mid to high freqs.

Solen does have some larger film caps that would work but I can't find ESR specs besides "Extremely Low". Price seems pretty similar, and since the Mundorf and TC caps were designed for tube amp power supplies I would choose them over the Solens.

[Bill Baker]

Have you tried these PS caps?

https://www.partsconnexion.com/capacitor_film_clarity_tc.html

Very low ESR specs, these will make a massive difference in your PS performance. I just got them for both my SET and my 6SN7 tube preamp. I have a Mundorf M-Tube Cap that is similar to the Clarity caps in the SET amp and the difference between that and an electrolytic was amazing, even though the electrolytic was in parallel with 2 80 uF oil filled motor run caps. The Clarity Caps have about an order of magnitude less ESR than the Mundorf Tube Caps, so I expect it will be even better.

Please do keep us posted on what you find with these caps. I have been looking at them for a new preamp but it will be a while before I can get to this part of the design. It would be great to hear what others experience with them in the mean time.

[DaveC113]

Please do keep us posted on what you find with these caps. I have been looking at them for a new preamp but it will be a while before I can get to this part of the design. It would be great to hear what others experience with them in the mean time.

I put it in my amp today and IMO the difference between the Mundorf and Clarity Cap are minimal, I think the Clarity is a little cleaner and maybe a touch more dynamic, but you'd need to set up a test with an A/B switch to get a good feeling for it. The differences between the Mundorf and the electrolytic were a game changer, huge... no need to switch back and forth.

The preamp is up next, but the caps are huge and I need to mount them through the top plate... should get it done sometime next week.

Also, these caps look really similar and have similar ESR specs to some big AVX and Cornell film caps on Mouser, but the prices are about the same... I was hoping to save some cash in the future but I don't think Clarity or Mundorf is reaming us on price.

[drummerwill]

  Keep puttin out the info.....This is good to know, Thanks

   Willie

[DaveC113]

I got the caps installed in my preamp, luckily I found a spot for them under the hood, the blue would have looked bad sticking up through my top sheet...

I also did a couple mods at the same time, I put in copper RCA jacks in the 1st input and main output... and I also figured out that I had output 1 and 2 mixed up, so I had been using the main output as the subwoofer output. The main out has RelCap copper foil output caps, while the sub out has Solen MKPs. I am sure the copper RCA jacks and using a $200 set of output caps vs. a $10 set made a difference too, but with the new Clarity TC series PS caps I am looking at low level noise, dynamics and a certain harshness to be removed based on my experience with my SET amp.

So long story short, these do the same for a preamp that they do for a power amp. The increase in clarity and dynamics is nothing short of amazing, and a HUGE upgrade over the electrolytic caps I was using.

I think these caps, whether you use Mundorf, Clarity or a similar non-audio specific model for wind turbines or whatever... these are going to have to be standard equipment for any high end tube audio manufacturer or DIY'er interested in top performance. Once you hear the difference there is no going back to electrolytics in the PS. The PS, especially the last stage filter, really is in the signal path and obviously has a massive influence on the sound of the amplifier.

Also, I want to point out that now, I think the preamp is a big improvement over the amp being driven directly by the DAC, before I wasn't so sure, but now it is definitely better, especially in the midbass... I think the pre drives the amp with more authorty vs. the DAC by itsself... at least that is what it sounds like.

[DaveC113]

I just finished putting in a 33 uF Clarity Cap TC series capacitor in my amp, to replace a 47 uF cap in the 1st stage of the PS, right after the 5AR4 rectifier tube. I went with 33 uF as it might be a little gentler on the rectifier tube at startup, I've seen a couple flashover with 47 uF caps in both my amp and preamp (when I had a tube rectified preamp). It's definitely more of the same improvement, but more subtle, as I was expecting since it's the 1st stage of the PS filter and is "hidden" behind the final cap and a choke.

While I had the amp apart I also replaced the Vampire brass binding posts with Pomona copper posts, replaced the .1 uF power tube electrolytic bypass caps with a 1.5 uF 250V Clarity ESA caps, and removed the driver tube's electrolytic bypass caps entirely (I don't need the gain). I also isolated the RCA jacks from the topsheet and used one of the RCAs as the ground point. Even though the jacks are really close together, the dual grounding paths caused a hum you could hear within a few inches of the speaker, now the amp is dead quiet. I just have a bit of hiss I need to track down in the preamp, it's not much but if I get rid of that I will have dead quiet tube amplification, which would be awesome.

The Aikido has two 47 uF 450V electrolytic caps in the 1st stage of it's PS, eventually I will replace them with the Clarity film caps, but I don't feel the need to order them up right away as the improvement is likely to be pretty subtle... probably worthwhile, but that's another $50-$60...

[DaveC113]

Willie, how do you like the 26 driver tube vs your 6SN7s? What kind of bias scheme did you use?

I am considering another SET amp using DHT drivers in filament bias... basically a power supply biasing the filament, and a single resistor from cathode/filament to ground. The resistor must dissipate both heater current and tube current, so it is not efficient... some tubes require huge resistors so it's not practical for all of them, but with some driver tubes you might only dissipate 10-20W.

[drummerwill]

 Yes the 26 vs the 6SN7,...... as an input tube for direct coupling to an output tube...
  Well for now I can only speak for the 26 DC 45 sound.... Not alot of gain you get from a
 single 26 input, but that about 0.85 watt of power on my Altec 604's sounds pretty good ........IMO.

   The 6SN7 DC 45 sound... that will be implemented in my next 3 stage Low power 845 SET build .
   For that amp maybe sometime down the road, .... switch to a 26 DHT input........even more fun !

     Later
     Willie