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Dynakit ST70

I'm leaning toward using the original values, or close to it, and upping the voltages on the can and electrolytics if that's advisable. Can I go up or down on capacitance to give more bottom end or it doesn't really make a difference?
 
More capacitance can help bottom end, more voltage rating just adds safety margin for the elyticap. 525 WVDC max is what's offered these days and what I used for the quad can.
 
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Blackdog61 said:
I got this https://www.dynakitparts.com/shop/multi-section-capacitor-1-2/ but initially put the 80 section after the rectifier, blowing it. Installed correctly, the amp sounds great and has been problem free for two years. After trying .1 and .25 Orange Drops on the driver board, I switched to the stock value little yellow Illinois caps and think the amp sounds better.
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The yellow Illinois caps are what came with my ST-35 kit. I was going to use something fancier like, PIO, Mundorf, etc., but the amp sounds great as is so I just left the yellow toosti rolls alone.
 
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There's a short list of things that can be done to improve performance and reliability for little additional money.
The larger capacity quad can is about the same price as the oem type and can provide greater LF reserve without stressing anything if installed correctly. Related, the enhanced "yellow sheet mod" for the rectifier socket to increase current reserve and protect the rectifier tube from spontaneous failure. There's the output socket mods to add 100 Ohm screen stopper resistors to protect the output transformers from screen flashovers.
There's also adding a CL80 or CL90 soft start MOV to the transformer primary circuit. If replacing the driver board with a new populated board, use one for 6CG8s rather than 7199. Otherwise, plug adapters are available to convert the original board sockets to the cheaper more common driver tubes.
 
Pio1980 said:
There's a short list of things that can be done to improve performance and reliability for little additional money.
The larger capacity quad can is about the same price as the oem type and can provide greater LF reserve without stressing anything if installed correctly. Related, the enhanced "yellow sheet mod" for the rectifier socket to increase current reserve and protect the rectifier tube from spontaneous failure. There's the output socket mods to add 100 Ohm screen stopper resistors to protect the output transformers from screen flashovers.
Click to expand...

I am planning on doing these and keeping the 7199's since they test good. What is a good place to source the Russian capacitors? @Lavane , where did you get yours? TIA
 
I bought them from tube4hifi when I ordered the kit. If you go to the Tubes4hifi site to look at them just make sure they are the same value that's used on the 7199 board. I have the VTA board and it may use a different value cap.
 
Okay got all my parts ordered up.Those Russian caps weren't that easy. Ended up with (2) K42Y-2-.047uF and (4) K40Y-9-.1uF. Went with the Jupiter Cosmos electrolytics. I still need to get tubes. I need (4) EL34 and (2) KT88. Does anybody have a sale or anything coming up? It was mentioned on another site that PSVane was a good spot with a year warranty.
Thoughts?

P.S. Can I sell my "vintage" Black Cats on ebay? lol
 
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I recommend EH 6CA7, Dave Gillespie likes TungSol EL34B.
I've not tried the EL34B bit haven't cared for the amp with any other EL34 I've used.
 
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I second the EH 6CA7's in this amp. I also like the KT-77's. I like the EH 6CA7's a little more though. They have a slightly better bottom end to my ears. I used the KT-77's for several years. I would still be using them if I hadn't tried the 6CA7's.
Several of the EL-34's I tried had a very nice midrange, but I found them lacking in other areas. Everyone's ears are different though.
 
Thats it. But buy a matched quad. Jim Mcshane, Tubesandmore, The Tube Store, or Tube Depot Are where I buy my tubes. Pretty much in that order.
 
The EH6CA7 delivers a full range transparent sound in my ST-70. The EL34s I’ve tried have a more fleshed out midrange but are softer at the extremes; more ‘Tubey’ if you will.
 
The 6CA7 beam tetrodes are more neutral and transparent sounding to me than any of the EL34 pentodes I've tried, I have not tried the Tungsol EL34B that @dcgillespie likes.
 
Blackdog61 said:
The EH6CA7 delivers a full range transparent sound in my ST-70. The EL34s I’ve tried have a more fleshed out midrange but are softer at the extremes; more ‘Tubey’ if you will.
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I have a Mark III I just revived and it has Tung Sol 6550's. Those are too hot for my speakers and push the upper end. I'm wanting to bring the levels more mid to bottom then high to mid, if that makes sense. That's what I want to accomplish with the ST-70.
 
The Tung Sol El34B might be better, although I haven’t tried that one. I didn’t care for the 6CA7s when running bright tubes in the line stage. Returning to Telefunkens was a good match. System matching is part of the fun.
 
Off Topic: Are the American Made Tung Sol 6550's sought after? One of the bottles is cockeyed.

Tung Sol

Tung Sol

  • Media owner MissionX
  • Date added

QSNWtwUUyELnkVzr5
 
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