Hi all,
I'm currently contemplating a replacement of my Quad 405-2's power supply capacitors (original ~20 year old electrolytic caps). Now the current values are 10k uf at 50v. I'm thinking to stick a higher voltage cap (63 or 80V) and I've just noticed that I could actually get 12k uf at 80v caps from my local retailer (SMH ELECTROLYTICs). Could replacing 10k uf caps by 12k uf ones be detrimental in any ways? Or is it just going to provide the circuit with a more stable source of current?
Any comments are very much welcome before I blow up my PA 🙂
I'm currently contemplating a replacement of my Quad 405-2's power supply capacitors (original ~20 year old electrolytic caps). Now the current values are 10k uf at 50v. I'm thinking to stick a higher voltage cap (63 or 80V) and I've just noticed that I could actually get 12k uf at 80v caps from my local retailer (SMH ELECTROLYTICs). Could replacing 10k uf caps by 12k uf ones be detrimental in any ways? Or is it just going to provide the circuit with a more stable source of current?
Any comments are very much welcome before I blow up my PA 🙂
Hi Sebastien,
The 12K caps are within tolerance, don't worry about putting them in. You start running into trouble when you take big steps up in capacitance.
-Chris
The 12K caps are within tolerance, don't worry about putting them in. You start running into trouble when you take big steps up in capacitance.
-Chris
Hello Sebastien,
If you google somewhat, you will find that the power supply capacitors have been replaced with 12000 uF up to 22000 uF values. The rectifier bridge, a 7A PM7A2Q, seems to be able to cope with them.
I have put two 22000 uF/63V (EPCOS) in a 405 because they fitted nicely in the clamps (50mm diameter, 80mm height). I still need to find some time to upgrade the modules themselves.
Cheers,
Jacques
If you google somewhat, you will find that the power supply capacitors have been replaced with 12000 uF up to 22000 uF values. The rectifier bridge, a 7A PM7A2Q, seems to be able to cope with them.
I have put two 22000 uF/63V (EPCOS) in a 405 because they fitted nicely in the clamps (50mm diameter, 80mm height). I still need to find some time to upgrade the modules themselves.
Cheers,
Jacques
Having measured the tan-delta of a lot of electrolytic capacitors, I have been surprised that how almost all of them, even the old ones, behave correctly from this point of view. Then I wonder if it is worth to change the reservoir capacitors of an amp without knowing their real state.
Hi,
mirroring Drc's post, I would go for increased temperature rating rather than increased voltage.
Although 50Vdc just works an increase to 63Vdc and 105degC may pay dividends in the long term.
Now it's finding a package that matches the foortprint.
mirroring Drc's post, I would go for increased temperature rating rather than increased voltage.
Although 50Vdc just works an increase to 63Vdc and 105degC may pay dividends in the long term.
Now it's finding a package that matches the foortprint.
Thanks for all the great info... The only caps I can find around here are rated 85 celcius (LPO and SHM).
As for checking for capacitance prior to replacing the caps, I just won't bother give the price of the caps... I'll end up paying at most 10$ per cap for the replacement units (12000 uF 63 or 80V).
Now would anybody recommend one brand over the other?
As for checking for capacitance prior to replacing the caps, I just won't bother give the price of the caps... I'll end up paying at most 10$ per cap for the replacement units (12000 uF 63 or 80V).
Now would anybody recommend one brand over the other?
Hi Sebastien,
Fresh new are better than brand name old. Just buy a good brand that's long in the industry. What choices do you have?
BTW, I am root too, but never log in that way. 😉
-Chris
Fresh new are better than brand name old. Just buy a good brand that's long in the industry. What choices do you have?
BTW, I am root too, but never log in that way. 😉
-Chris
Well, I'm from montreal, so my source for componants is baiscally solen (www.solen.ca). They carry many brands of caps, but the only two brands that will actually provide me with the specs I need are the LPO by ELNA and the SHM by UCC.
Suggestions?
And no, I never login directly as root 🙂 I've been in the business of "being root" for over 12 years... 🙂
Suggestions?
And no, I never login directly as root 🙂 I've been in the business of "being root" for over 12 years... 🙂
Hi Sebastien,
Either one sounds like a good bet. They are both well respected brands.
I have not researched the particular type. Look for the lowest ESR and highest allowable ripple current.
-Chris
Either one sounds like a good bet. They are both well respected brands.
I have not researched the particular type. Look for the lowest ESR and highest allowable ripple current.
-Chris
I have replaced with RIFA 15mF/63V and with the Net-.Audio double PSU kit, which I can recommend.
Don't know about the state of the old elcos in the sense referred to here, but the sound got better...don't forget to change the old elcos on the board either...
Don't know about the state of the old elcos in the sense referred to here, but the sound got better...don't forget to change the old elcos on the board either...
The Net-Audio kit splits the transformer into two, has two recifiers, and two elcos per channel, just like the Quad amps from 306 and onwards...
Hi,
if the 405 runs both channels off one set of single rectifier and one pair of 12mF caps, then you may get a boost in performance by duplicating the PSU from rectifier onwards.
so instead of 12mF+12mF would become 15mF times 4.
The difficult part would be packaging it to fit inside the case.
if the 405 runs both channels off one set of single rectifier and one pair of 12mF caps, then you may get a boost in performance by duplicating the PSU from rectifier onwards.
so instead of 12mF+12mF would become 15mF times 4.
The difficult part would be packaging it to fit inside the case.
Check out www.net-audio.co.uk, it's all there...(I am not connected to the company, just a satisfied customer)
Wow, lots of very good advice. Thanks to you all. I'll start by going 12 or 15mf at 63V and see what that will give me. (given the pricetag of 5-10$ per cap, its a cheap experiment). Then I'll definately consider going with the double mono setup.
I've read alot of comments on upgrading the 405s and will most probably start with the PSU caps, the RCA plugs (I've already done it but in a very bad way with very bad component which I'll fix up properly) and change the caps on the amps. I also want to replace the opamps, but I'm just not that good with a soldering iron 🙂 I'll probably get that done later.
Has anybody changed the resistances to accomodate 1.5v source?
I've read alot of comments on upgrading the 405s and will most probably start with the PSU caps, the RCA plugs (I've already done it but in a very bad way with very bad component which I'll fix up properly) and change the caps on the amps. I also want to replace the opamps, but I'm just not that good with a soldering iron 🙂 I'll probably get that done later.
Has anybody changed the resistances to accomodate 1.5v source?
no need to solder the opamp, it has a socket, crappy, but a socket...OPA134 is OK, but decouple the opamp with ceramic 0.047uF on +/- to earth...
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