Working on my WB Laurel Mono Blocks finally but need capacitor info help.

[Marvel]

6 hours ago, hron61 said:

Aren't those schematics for the stereo version?

I'm sorry, I uploaded the wrong ones I'll dig in my files some more, unless you already have the schematics.

[henry4841]

On 1/12/2024 at 6:07 AM, henry4841 said:

Marvel and other electronic geeks, is the top tube on the input a CCS? Looks to me like it is since the signal is tied to the cathode of that tube. Totem pole perhaps. I am too lazy to do research hoping more talented tube guys know without doing research. Pretty sure Maynard knows as well as others. 

Tube Fanatic, Maynard in an email says the two input tubes are being run as a mu stage. Learn something new everyday. Here is the link he sent me. 

 

http://audio.fam-gelder.nl/index.php/alan-kimmel-artikelen/9-why-use-the-kimmel-mu-stage-2001-alan-kimmel

 

[hron61]

On 1/10/2024 at 3:32 PM, amped said:

I was using a GFCI -something like this on my VTA ST120:

https://www.amazon.com/TRC-Southwire-14650013-6-120-Volt-1800-Watts/dp/B000XU5MEG/ref=sr_1_16?crid=1MR1T5P0YFFL1&keywords=gfci+plug&qid=1704928910&sprefix=gfci%2Caps%2C85&sr=8-16)

 

All was well but I checked my wall current. I forget the amount and it was a bit high so I got one of those circuit specialists red 5A variable transformers and the instructions said NOT to use it with a GFCI so I quit using the GFCI. A reason wasn't mentioned nor did I ask but the voltage thing bothered me more.

 

UPDATE: I found this on the website:  "Please note that Variacs are not compatible with most GFI (Ground Fault Interruption) wall outlets. Because the load is very inductive, the Variac represents a fault and will cause the breaker in a GFI to trip."

 

BTW, the analog meter on that "variac" is not accurate.

 

Many people way smarter then me on here...

 

 

 

Interesting, never saw a portable GFCI before.

 

Thanks for posting that info about usage too.

I may have to rethink using a variac here in the home.

I can always go to a friends house and use it there I reckon.

 

Question...Would a dim bulb limiter be ok with or without a GFCI installed?

Outlets here are not grounded.

[John Warren]

3 hours ago, hron61 said:

Interesting, never saw a portable GFCI before.

Common in industrial locations.  If you have a portable water pump, wet-vac or using power tools in wet areas this is what you want.

 

 

If you work on vintage, old and/or faulty electronics, lots of "gotchas" and surprises.  Here's my take, connect chassis directly to panel Earth.

 

 

 

Regarding Variac, the red, Chinese Amazon units are the POS.  Can't run at rated kVA without getting hot AF.  Wipers aren't accurate or don't function until the wick is turned halfway up then wham!  The internal winding is likely a better fuse than the fuse.        

 

A Staco 12A variable transformer runs about $650 and will source 1.4kVA all day and barely get warm.

 

[82 Cornwalls]

You can find a used Staco for $100 or less.

I looked a lot and wasn't sure how much I would use one since a friend has a variac, but finally got one for $35-$40? that works great.

[NOSValves]

4 hours ago, hron61 said:

 

 

Interesting, never saw a portable GFCI before.

 

Thanks for posting that info about usage too.

I may have to rethink using a variac here in the home.

I can always go to a friends house and use it there I reckon.

 

Question...Would a dim bulb limiter be ok with or without a GFCI installed?

Outlets here are not grounded.

 

   How high is the wall voltage that you use a variac to knock it down? 

[amped]

"Regarding Variac, the red, Chinese Amazon units are the POS.  Can't run at rated kVA without getting hot AF.  Wipers aren't accurate or don't function until the wick is turned halfway up then wham!  The internal winding is likely a better fuse than the fuse.        

 

A Staco 12A variable transformer runs about $650 and will source 1.4kVA all day and barely get warm."

 

My red, Chinese, Circuit Specialists "POS" doesn't get hot and I've not noticed it get warm either in the three years of having it. I'm using a 5A and it works fine for what I need. My wall current fluctuates between 119 and 124. My amp likes 115-117v. If I trusted myself to build a bucking transformer, I'd have done this. Same reason when I searched for an American Staco or Variac, the ones in my price range looked like they'd need repair or set my house on fire.

 

Sorry, I'm not an engineer

 

 

 

[NOSValves]

7 minutes ago, amped said:

"Regarding Variac, the red, Chinese Amazon units are the POS.  Can't run at rated kVA without getting hot AF.  Wipers aren't accurate or don't function until the wick is turned halfway up then wham!  The internal winding is likely a better fuse than the fuse.        

 

A Staco 12A variable transformer runs about $650 and will source 1.4kVA all day and barely get warm."

 

My red, Chinese, Circuit Specialists "POS" doesn't get hot and I've not noticed it get warm either in the three years of having it. I'm using a 5A and it works fine for what I need. My wall current fluctuates between 119 and 124. My amp likes 115-117v. If I trusted myself to build a bucking transformer, I'd have done this. Same reason when I searched for an American Staco or Variac, the ones in my price range looked like they'd need repair or set my house on fire.

 

Sorry, I'm not an engineer

 

 

 

   Chances are your amp will run just fine and dandy at 119 to 124 AC volts... But I see no reason that you couldn't plug the variac into the wall plug your GFI unit into the variac and then the amp if you want to be ultra safety minded, the variac should not mess up the GFI if it's before the GFI...plugging the variac into the GFi and the amp into the variac would most likely cause the GFI to trip it fuse. 

[amped]

Thanks for the tip. My amp is a Tubes 4 hifi VTA ST 120. Bob Latino recommended that specific "variac" and I settled on that one because the U.S. alternatives were out of my range. I'd love one of those Brown Boxes (?) where you can dial in specific reductions but those aint cheap either.

 

I'm using an S/S rectifier as this amp runs 5AR4's hard. I hadn't blown one but have an auto bias board that delays the hi voltage. I did just get a Brittish NOS GZ34 for backup.

 

I'll definitely give the GFCI another shot in the right order. 

[NOSValves]

35 minutes ago, amped said:

Thanks for the tip. My amp is a Tubes 4 hifi VTA ST 120. Bob Latino recommended that specific "variac" and I settled on that one because the U.S. alternatives were out of my range. I'd love one of those Brown Boxes (?) where you can dial in specific reductions but those aint cheap either.

 

I'm using an S/S rectifier as this amp runs 5AR4's hard. I hadn't blown one but have an auto bias board that delays the hi voltage. I did just get a Brittish NOS GZ34 for backup.

 

I'll definitely give the GFCI another shot in the right order. 

 

  It does run the 5AR4 hard in fact way beyond spec which is why they start arcing over pretty quick in most cases especially any modern production 5AR4. I have no idea why Bob didn't design it with dual 5AR4's? with SS rectification you probably should be using something to get the voltage down since using SS results in much less voltage drop. The SS rectifier solves one problem but creates a running voltage problem. 

    By the way I hope you know that the number on the dial or built in gage of a simple variac like your using are never accurate. You need to confirm what the amp is being fed! 

         Good luck Craig

   

 

[amped]

I had not personally had a rectifier blow but I avoided the Chinese one in favor of the Russian Tung Sol.  Roy Motram the designer of the circuit did so 30 years ago and maybe with the rectifiers of the time it was fine. He and Bob Have retired in the last year or so. Roy did create a dual rectifier kit before leaving. They are both occasionally still on the dynaco forum.

 

As for the "variac", yes, I know about the dial and the analog meter. I always use a VOM to check. I also put my own marks on said dial. 

 

Thanks!

 

Apologies to the OP. Never meant to hijack your post.

[NOSValves]

9 minutes ago, amped said:

I had not personally had a rectifier blow but I avoided the Chinese one in favor of the Russian Tung Sol.  Roy Motram the designer of the circuit did so 30 years ago and maybe with the rectifiers of the time it was fine. He and Bob Have retired in the last year or so. Roy did create a dual rectifier kit before leaving. They are both occasionally still on the dynaco forum.

 

As for the "variac", yes, I know about the dial and the analog meter. I always use a VOM to check. I also put my own marks on said dial. 

 

Thanks!

 

   Modern production or vintage 5AR4 there is no reason to design an amplifier to use the tube beyond it's specification... No excuse for reckless engineering... To put it in laymen's terms there is no way to reliably eeck out more than about 60 watts of power from a single 5AR4 vintage or modern. Sure vintage will take it for a bit longer but as scarce as they are why burn them up? By the way the Tung-Sol reissue 5AR4 is just the Sovtek with a base change with a vintage name stamped on it (with a higher price). As is all the modern production 5AR4 tubes with vintage names. You can thank New Sensor corporation out of New York for that scam job along with every other tube type with a vintage name today. Blatant scams if you ask me... 

   It's the world we live on today no integrity anywhere..

 

        Cheers Craig

 

       

[hron61]

On 1/14/2024 at 7:22 PM, amped said:

 

 

Apologies to the OP. Never meant to hijack your post.

 

No worries. 😀

 

 

[henry4841]

I personally have quit using tube rectification on the amplifiers I now build. But you do need to bias the tube circuits with less current being that the voltage will increase with SS diodes if you want to do it correctly. Many do not and get away with doing so but it will probably shorten the tube life depending on the amplifier of course and how it was biased when purchased. SS rectification is much less trouble, expense, and has a much longer life expectancy than a vacuum tube. Many say they like the sound better with a tube but that is not what it is supposed to do. A tubes job for rectification is to convert AC into DC voltage only and not to flavor the sound. 

[NOSValves]

4 hours ago, henry4841 said:

I personally have quit using tube rectification on the amplifiers I now build. But you do need to bias the tube circuits with less current being that the voltage will increase with SS diodes if you want to do it correctly. Many do not and get away with doing so but it will probably shorten the tube life depending on the amplifier of course and how it was biased when purchased. SS rectification is much less trouble, expense, and has a much longer life expectancy than a vacuum tube. Many say they like the sound better with a tube but that is not what it is supposed to do. A tubes job for rectification is to convert AC into DC voltage only and not to flavor the sound. 

 

Most of the difference between the performance/sound of SS vs Tube rectification is from people that do exactly what is done with the amplifier in question. Plugging a SS tube replacement slug into an amplifier designed for a tube rectifier is a serious compromise. SS diode take entirely different power supply designs and voltage correction. SS rectification require larger filter banks and some way to lower the voltage back to design to allow proper biasing of the output Tubes. Simply lowering the bias is a band-aid. Every single stage of the amp will be operating at an over voltage which indeed will result in a sonic character change. In the case of Dynaco or Dynaclone like this moving to SS rectification on many of the amplifiers pushes the voltages over the specification of the power supply capacitors which are already run too close to spec. In many cases.

      If the user can't hear the difference they might be better served to get rid of there tube gear all together. 

 

         Craig 

[henry4841]

4 hours ago, NOSValves said:

 

Most of the difference between the performance/sound of SS vs Tube rectification is from people that do exactly what is done with the amplifier in question. Plugging a SS tube replacement slug into an amplifier designed for a tube rectifier is a serious compromise. SS diode take entirely different power supply designs and voltage correction. SS rectification require larger filter banks and some way to lower the voltage back to design to allow proper biasing of the output Tubes. Simply lowering the bias is a band-aid. Every single stage of the amp will be operating at an over voltage which indeed will result in a sonic character change. In the case of Dynaco or Dynaclone like this moving to SS rectification on many of the amplifiers pushes the voltages over the specification of the power supply capacitors which are already run too close to spec. In many cases.

      If the user can't hear the difference they might be better served to get rid of there tube gear all together. 

 

         Craig 

Good point Craig about increasing the voltage on the specific amplifier you mentioned, Dynaclones, and the filtering caps not up to the task of higher voltages. Always best to stick with what came with your amplifier and leave playing to those qualified to do so. I was speaking of my own builds going with SS over tube rectification. 

[hron61]

Update..

I have all the caps ordered now.

Some are here and some are still in transit.

The only significant change I made were the jensen pio caps.

I decided to use the Duelund CAST-PIO-Cu Pure Copper Foil.

All the Solens were replaced with the same.

The xicons were replaced with modern Vishays and one Nichicon.

I found a few Elna Cerafines, bought extra for future in case.

Only the Cerafine 47uf x 47uf 500v dual section power cap remains.

Hopefully it is ok still.

Still waiting on other supplies before I can start the project.

Thanks to all that have replied here and a special thanks to Henry4841,

we have be exchanging PM's and he has given me valuable info to use going forward with this.

I built these but only because I followed the manual to a tee, I know squat about electronics or tube amp circuits, I only know enough to be dangerous.

Building cables and soldering I can do pretty well.