The truth about electrolytic capacitors? Large can or multi-cap banks?

undertow · « **on:** 23 Mar 2016, 04:48 pm »

Just curious of any thoughts or opinions on this.

I see Mundorf now makes large power supply electrolytic 'cans' that may or may not be a big deal.

http://partsconnexion.com/capacitor_ele_mundorf_hc.html

I know Cornell Dubllier was more or less the "Audio" standard for years with big power caps used in everything from Krell, Levinson, Threshold etc...

http://partsconnexion.com/capacitor_ele_cornel.html

Are these new Mundorfs any better? Or are there even better suggestions?

Also, I know there are some split opinions on this, but you can just replace the "Big cans" with multiple smaller caps rather easily.

Any thoughts if it's truly better to go this route on more classic amps, and just throw a board in with multi-banked caps vs. a couple big can replacements?

One advantage I can say from a physical perspective is the big can amps which I am looking at have as large as 8 gauge battery cables feeding the power caps with big bolt on lugs! This is easily replaced with smaller boards and wiring, but obviously the high current, and big conductors can play some small part in the sound quality vs. using some 14 gauge into small legged Nichicon caps. But maybe this would not be the case.

By the way I know the old Threshold amps for an upgrade they did remove the large caps in exchange for a multi-cap bank... Not so sure this was a huge sonic advantage, or more toward the fact it kept the pricing a lot lower because this was done as a normal maintenance procedure due to the age of the caps needing replacement as much as it was an upgrade ultimately.

*Scotty* · « **Reply #1 on:** 23 Mar 2016, 06:29 pm »

The Threshold upgrade lowered the total ESR of the power supplies capacitors, this in turn lowered the dynamic impedance of the power supply. Theoretically the Mundorf caps have a lower impedance than the stock capacitors. I have used Jensen 4-pole caps as well as the Mundorf 4-pole clones which may have also been made by Jensen. The 4-pole caps have been the best sounding caps for linear supplies I have ever heard.
The patent was held by Sprague and they were designed for switching power supplies which need a very low impedance at high frequencies.
Scotty

undertow · « **Reply #2 on:** 23 Mar 2016, 06:40 pm »

Scotty,

Thanks

I do understand there are some measurable differences in the ESR for sure when paralleling caps. Not sure if it helps any old power supply or not vs. the big caps.

Only thing is I know the couple applications I was looking at only have standard 2 pole caps, not 4 pole. Like this exactly shown below using 2 large caps, 2 taps each...

Not sure we can use a 4 pole, or do you parallel the taps on the 4 pole or something to get lower ESR, and can use them in place of the 2 pole caps? -

Folsom · « **Reply #3 on:** 23 Mar 2016, 08:20 pm »

Several smaller caps is better than just one or two larger ones, in the right application. I've found the actual capacitor determines the sound more. For example I use to use Panasonic FC. I'd use many small ones. But then I found other caps that sounded so much better that I don't bother with FC ever again. I've found no amount of Panasonic FC's would overcome the sound of a single capacitor that simply sounded better.

undertow · « **Reply #4 on:** 23 Mar 2016, 08:23 pm »

Yeah its always tricky with caps. Film caps even and they are easier to tell specifically when in much more critical audio signal locations, but Electrolytics its a mixed bag. But I am thinking that putting the 4 pole over the 2 pole having the isolated input and output taps would be a good upgrade regardless. Probably going to go that route now that I figured out how to wire it.

Folsom · « **Reply #5 on:** 23 Mar 2016, 08:32 pm »

A big problem with electrolytic 4 pole vs 2 pole is that the 2 pole are rarely on a low inductance PCB board design. The gap in performance gets a hell of a lot lower when you use copper pours instead of tracing.

undertow · « **Reply #6 on:** 23 Mar 2016, 08:40 pm »

Yeah well I just got a great deal with like 40% off on the big 100 volt / 4 - pole Mundorfs --- 47,000 uF at only about 100 bucks each. So I think it will work out well vs. the standard 2 pole Cornells in there. These Mundorfs are double the Voltage though at 100 volt vs. what I think was 50 volt in there, no big deal I can mount the new Mundorf clamps as I am sure they are bigger diameter.

It's already a killer classic amp, sounds perfect right now, but figured when it's such an easy target, and replacement in order to take these over the top why not?

Thanks!

*Scotty* · « **Reply #7 on:** 23 Mar 2016, 09:03 pm »

Be sure to connect the caps up exactly as indicated by the circuit diagram. They will not tolerate a mistake here. It was also good that you purchased 100volt rated caps even though the old caps were rated for 50volts. If the 4-pole cap sees even 2volts more than it is rated for IT WILL DIE. The 4-pole caps don't have the typical +10% tolerance to over voltage conditions that a conventional electrolytic cap has.
These caps, as well as solid polymer aluminum electrolytic caps, should never be bypassed.
Scotty

undertow · « **Reply #8 on:** 23 Mar 2016, 09:06 pm »

Understood... Yeah here is the current photo I have inside my amp. I think I might have to cut all the cables going in anyway to separate the terminals, plus there is a Bridge putting the caps in series on one terminal. I probably have to build a new bridge cable anyway as I am pretty sure these new Mundorfs will not sit in the same distance with the terminals to use that existing bridge.

undertow · « **Reply #9 on:** 24 Mar 2016, 03:00 pm »

Okay guys I need a little help... Its an easy upgrade, but the "Negative" current flow, and a few of the taps are now confusing me on the 4 pole caps since we gotta get an in out direction on everything.

See attached photos, one is with my diagram markups to tell you what the cables all go to, and one is plain so maybe you can just post back the photo with the exact +, - / In and outs I should be following on the 8 new taps... Going from 4 taps to 8 taps, and following the ground with caps in series reversed like this is a little bit of a mind twister. But maybe the flow of the negative does not matter? I don't know in this case.

A ground is normally just a ground, but in this case with the caps being series together on one of the in out taps via the 4-pole design, and a few other concerns I just want to make sure we have everything flowing the right direction here. You will see in the photo like the Orange line coming direct off the transformer, its not even rectified to DC and it hooks to the positive of the cap, but not sure once it flips positive to negative on the next cap if its an in our an out?

Also, the main green ground I am not really sure if direction flow is going back to the rectifier, or does it even matter which is in and out on the negatives? I clearly marked the Positive sides of the existing caps for reference because the + symbol is under the wiring and too hard to get in the photo..

Thanks, hopefully it is pretty clear in the photo what is going on. Its an easy upgrade, but I am a little thrown on the wiring of these for sure!

undertow · « **Reply #10 on:** 24 Mar 2016, 03:08 pm »

Trying to upload a larger image does not seem to be working.

Speedskater · « **Reply #11 on:** 24 Mar 2016, 03:44 pm »

That looks like a typical plus & minus supply.
with:
a] The Plus supply connected to the "+" terminal and the Common/Ground connected to the "-" terminal of one capacitor.
b] The Minus supply connected to the "-" terminal and the Common/Ground connected to the "+" terminal of the other capacitor.

undertow · « **Reply #12 on:** 24 Mar 2016, 03:59 pm »

Well this needs to run thru "4-pole" caps, the Caps in the photo are just 2- pole - that's the point we are converting it here so it's not a straightforward + / - connection anymore and every [IN / OUT] needs to be determined. Lets try it this way

Orange wire is coming directly off the Transformer - Should this feed a Positive [+ in], or a Positive [+ out] on a cap? In other words that would determine the current flow direction for me as to which way that series connection in the middle should be, and which tap IN or OUT the black wire to the main amp board should be on the other side. Currently the Orange wire on the transformer is simply feeding a standard 2 pole positive + side of the cap. But with a 4-pole I don't know if that would be determined in or out on a new 4 pole cap.
_______________________________________ _______________________________________ ___________________________________

Now the green wire connected at the negative on that cap is with the big white cable coming off the Negative [-] on the bridge Rectifier. ON a 4- pole which would be the in, and which would be the out?

_______________________________________ _______________________________________ ___________________________________

Speedskater · « **Reply #13 on:** 24 Mar 2016, 04:12 pm »

Don't connect electrolytic capacitors to power transformers. The caps connect to the bridge rectifier diodes. Not the "~" terminals. Use the "+" and "-" terminals.
The only exception would be a "DC Blocker" device and I won't go there.

undertow · « **Reply #14 on:** 24 Mar 2016, 04:21 pm »

Please read again... Currently this amp is in its correct manufactured condition unaltered in the photo, exactly as seen in photo has the ORANGE transformer wire directly connected to that caps Positive Terminal. Then you see the black bridge between the 2 caps they are now connected with the positive of one cap to the negative of the other cap with the orange wire obviously going back to the black wire on the negative terminal of the second cap which is going to the driver/amp board.

Currently this amp is 100% perfectly operational, however has older 2 pole caps in it, and I was pointed toward replacing these caps since they needed to be re-freshed anyway with 4-pole caps.

That being said I assume that Orange wire coming off the transformer is not AC voltage feeding into the cap, I assume it's just a common / ground or something to the transformer which is why it's hooked this way. But it does confuse direction as on the other cap where the black wire is would be current coming back from the amp board it seems, and that is actually feeding current back toward the orange wire, but again the IN/OUT configuration of the caps in this case is pretty unclear to use the 4-poles in this scenario. Which is why I am trying to get a determination on how to go about this hookup...

Again what you see in photo is STOCK, and trying to convert to use 4-pole caps, opposed to the original 2-pole caps. The IN/OUT directions are a bit skewed I agree due to the way its wired, and going back toward the transformer with the 2 caps in series on top of it reversing the in/and out again on me.

Folsom · « **Reply #15 on:** 24 Mar 2016, 04:36 pm »

Can you please draw schematic? More pics?

undertow · « **Reply #16 on:** 24 Mar 2016, 04:51 pm »

Folsom,

No problem... Give me 10 its coming up

undertow · « **Reply #17 on:** 24 Mar 2016, 05:13 pm »

Folsom,

I made this as clear, and clean as possible to show exactly whats going on

hopefully somebody can create a 4 pole version and post here too.

By the way I believe the green ground wire is going direct to chassis, I might be wrong on that, not sure it will matter in this case because it goes "Somewhere" on the other side of that rectifier which we don't need to know, I just need to know how to run the 4 pole, and the directions of everything.

Thanks

Folsom · « **Reply #18 on:** 24 Mar 2016, 06:30 pm »

undertow · « **Reply #19 on:** 24 Mar 2016, 06:33 pm »

After much deliberation, and then some consultation it looks like the new wiring Schematic should be this exactly...