Someone suggested replacing a pair of 5V4 recs in a Cary amp with the Weber Copper Caps which is a solid state version of the 5V4. Has anyone tried it and if you have, how did it affect the sound and was it reliable? Thanks.
The Webber part is OK in a guitar amp. Do NOT use it in a HIFI unit.
I've heard tell that the now retired Dennis Had took considerable liberties with 1st filter cap. limits. Please describe your unit. Better yet, post a schematic.
I've heard tell that the now retired Dennis Had took considerable liberties with 1st filter cap. limits. Please describe your unit. Better yet, post a schematic.
I don't have a schematic of my SLA 70A Signature which is a Class A design, but attached is the Class AB version of the amp which uses 5AR4 recs instead of the 5V4. The two schematics are almost identical. Thanks.
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Do you see the 1100 μF. 1st filter cap.? That's a guarantee of trouble. A 5V4 really should be held down to 10 uF. in the 1st position. While it's true that 5AR4s are (for vacuum rectifiers) extremely tolerant of largish 1st filter caps., you can't go beserk. The 5AR4 limit is 60 μF.
Looks like Cary produced some VERY dubious designs. 🙁
Looks like Cary produced some VERY dubious designs. 🙁
Thanks and yes, this was pointed out to me previously as a potential problem but another person mentioned that Cary also uses a choke to keep things stable. I don't know enough about tube electronics to really comment so I guess the question is this:
I've had a pair of Sylvania 5V4's in this amp for close to 10 years with no problem. I recently replaced them with a pair of RCA's in which one shorted after about 3 months. Should I consider the melt down of the RCA just a bad tube destined for the trash can or did I get lucky with the Sylvania's? Either way, I don't think that using Weber CC's is the answer.
I've had a pair of Sylvania 5V4's in this amp for close to 10 years with no problem. I recently replaced them with a pair of RCA's in which one shorted after about 3 months. Should I consider the melt down of the RCA just a bad tube destined for the trash can or did I get lucky with the Sylvania's? Either way, I don't think that using Weber CC's is the answer.
I have a silicon version with the same socket for 5AR4 to replace, but the B+will turn higher, and sound different, even 5V4 also sound different to other direct heating tube like 5U4, depend on your personal choose, you should check amp's current still normal before to replace a new rectifier to it
tony ma
tony ma
As far as I know, the copper cap is just a pair of SS diodes, a resistor (of the same value as the internal resistance of the tube) and a thermistor. I would have thought it would be an ideal substitute for an overworked 5V4.
Is it possible that the 1100uf cap is the one after the 500R 1W resistor and the 22uf is the first cap? That would be a rectifier friendly design.
If not: To answer your question, I suggest you download a copy of PSUII and model that power supply circuit. I think I'd look at adding a choke, changing some cap values (or perhaps just reversing their order) and keeping the 5AR4.
Monjul,
Without a truly accurate schematic, a certain amount of guessing is going on.
All indications are that your amp does not have a PSU choke.
Your Sylvania tubes survived by dumb luck. The "pedigree" of RCA tubes is beyond reproach.
Unless you are willing and able to make modifications to the unit, put the Weber CC rectifiers in and live with the sound you get.
If it were my amp, I'd put Chinese 5AR4s from a reliable vendor, like Jim McShane, in. I'd make the 1st filter cap. 100 μF. and add a choke of approx 1.5 H. between the 1st filter cap. and everything already in place.
BTW, another questionable item is paralleling plates from both rectifiers. The experience of John Atwood, a highly competent designer/builder, suggests that paralleling the plates of each rectifier tube and connecting each tube to only 1 end of the rectifier winding is the proper technique.
Without a truly accurate schematic, a certain amount of guessing is going on.
All indications are that your amp does not have a PSU choke.
Your Sylvania tubes survived by dumb luck. The "pedigree" of RCA tubes is beyond reproach.
Unless you are willing and able to make modifications to the unit, put the Weber CC rectifiers in and live with the sound you get.
If it were my amp, I'd put Chinese 5AR4s from a reliable vendor, like Jim McShane, in. I'd make the 1st filter cap. 100 μF. and add a choke of approx 1.5 H. between the 1st filter cap. and everything already in place.
BTW, another questionable item is paralleling plates from both rectifiers. The experience of John Atwood, a highly competent designer/builder, suggests that paralleling the plates of each rectifier tube and connecting each tube to only 1 end of the rectifier winding is the proper technique.
Eli,
I don't have a better schematic, but I have looked at pics of the unit. A choke is nowhere to be found - it would be way too big to miss!
I don't have a better schematic, but I have looked at pics of the unit. A choke is nowhere to be found - it would be way too big to miss!
Eli,
I'm not sure I follow you. Are you suggesting that one should use each 5AR4 as a half wave rectifier? Let's say, cut the wire to pin 4 on one and pin 6 on the other?
Not quite. The schematic provided by the OP shows 1 plate of each tube connected to an end of the rectifier winding and the 2nd plate of each tube connected to the other end of the rectifier winding. JA's experience shows that you should tie the plates of each tube together and connect 1 tube to an end of the rectifier winding and the 2nd tube to the other end of the rectifier winding. Each tube is set up to be a 1/2 wave rectifier using its full current handling capability. A pair of 5AR4s is good up to 1/2 A. of B+ draw.
"Your Sylvania tubes survived by dumb luck. The "pedigree" of RCA tubes is beyond reproach."
Thanks for the replies.
I would never question the pedigree of RCA tubes. I use many in my guitar amps and they're not cheap.
Also I should add that the original rectifiers last quite a long time and never failed before I replaced them with the Sylvania's as routine maintenance.
Again, I'd like to know if anyone has experience with and an opinion formed about the Weber's effect on an amps sonics.
Thanks for the replies.
I would never question the pedigree of RCA tubes. I use many in my guitar amps and they're not cheap.
Also I should add that the original rectifiers last quite a long time and never failed before I replaced them with the Sylvania's as routine maintenance.
Again, I'd like to know if anyone has experience with and an opinion formed about the Weber's effect on an amps sonics.
Pedigree aside, any tube can have shelf life issues and that is indeed a possibility that should not be overlooked. But if you have a first smoothing cap sized so far beyond reasonable design practice, you will probably continue to short rectifier tubes. You should crawl in there and have a look for yourself. Make a drawing. Maybe post some photos.
Here's a pic of the innards. (The coupling caps were being swapped out which is why they aren't there). Yes, I don't see a choke either. Only a C and R across the filter caps.
Attachments
OK. I've had the Weber Copper Caps in since Tuesday and have about 10 or so hours on them. I hope that one chap is right who told me that they require a break-in in which they begin to open up because as of right now, the amp sounds like it sold it's soul to the Devil for $44 + shipping.
The sound right now is thin, grainy, compressed and the images in the soundstage don't sound like they have their own place in the soundstage. In essence, it sounds like everything I've always hated about Soiled State.
I'll give these things more time to break-in but I'm not optimistic.
The sound right now is thin, grainy, compressed and the images in the soundstage don't sound like they have their own place in the soundstage. In essence, it sounds like everything I've always hated about Soiled State.
I'll give these things more time to break-in but I'm not optimistic.
Hi Dave. My expertise is limited here. Exactly how would I wire in the choke? Mounting shouldn't be an issue. Thanks.
You are going to "break in" a diode? Good luck.
Those copper caps things are designed to simulate all the "bad" qualities of a rectifier tube that make them work in guitar amps. For example the prime effect guitar players are looking for is called "sag" this is where dynamics are compressed because a loud bass note will suck the voltage out of the power supply. Those old 50's vintage guitar amps had very much under sized filter caps and had quite a bit if resistance in their power supplies. Purposely NOT HiFi but they did not need to be. A guitar is a mono source with a frequency range from about 80Hz the 8KHz. Guitar amps typically have the mid frequencies attenuated and have THD from about 10% to 50% or even over 100% in some cases. Those copper cap things are designed to add "sag" to an amp.
I'd take the copper cap out and replace it with a pair of UF4007 diodes (or whatever is rated for your current and voltage). You can actually simply stuff the diode leads right into the tube socket, but I'd use solder. Then as suggested adding a choke is good. Replace the first resister in the power supply with a choke. You want the biggest choke you can have that has DC ohms about the same as the resistor it replaces or if you've used the uf4007 diodes a few more DC ohms is OK.
The diodes plus choke will have an effect opposite to the copper cap thing
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