How many Hammond 155J chokes?

[tpatton]

I've just put a second Hammond 155J choke into a Seduction.  The 1st replaced a 1000 ohms resistor between terminals 12 and 15.  The second replaced another 1000 ohms resistor between terminals 15 and 25.
There are three 220 uF caps in this area: I've upgraded the innermost two, the furthest in (terminals 11 and 12) by both sides of a Mundorf M-Lytic 100 + 100, the next furthest in (terminals 14 and 15) by a JJ 200 uF.

Will I get any benefit out of that second 155J choke, or am I just overdoing the upgrades, as usual?  (I have TX2352 Vishays in as 47K ohms input load resistors, as always.)

Thanks for any expert advice on this, or just opinions.

[JC]

As a general rule, chokes in the PS tend to impede changes in current flow.  In that respect, they tend to make the PS "tighter", or less apt to fluctuate with the demands placed upon it.  The filter caps, on the other hand, tend to want to keep the Voltage constant, so the caps and the chokes compliment each other.

Whether or not this has an audible effect in your particular application, well, you will have to be the judge of that!  Please post your impressions!

[Doc B.]

You can also model the circuit in PSUD and see what changes the additional choke will make to the power supply output. That's how we do it here at the Chateau.

[Paul Birkeland]

You will certainly get some benefit out of that second choke.  You would probably get some benefit from putting the Panasonics back in place of the JJ electrolytic cap (this is from my experience).

The chokes will actually let you use much less capacitance for similar ripple reduction.  You could probably go down to 33uf and use film caps (250v is fine).  

[bernieclub]

You can also model the circuit in PSUD and see what changes the additional choke will make

Where does one find the impedances required in PSUD of the various power transformers??
Thanks,
Bernie

[tpatton]

Thanks Paul B for your intriguing idea about using film caps, though I've always liked what the Mundorf M-Lytic "double" caps have done for me.  JJ electrolytics are thoroughly rotten?  Pity.  As for modeling the circuit as Doc B and Bernieclub have suggested, PSUD, to this Newbie, just looks like a poor spelling of SPUD.  I have no idea how even to begin to do that.  I'll just assume that the second 155J does indeed help.

[Paul Birkeland]

No problem. It's not that the JJ's are rotten, but rather that the Panasonics are carefully chosen There are many less expensive options out there that could be shipped with the kits, but the low ESR and good lifetime specs of the Panasonics put them at the top of the list.  I don't remember, does JJ specify ESR?  I have a bunch of them in my parts bin, so perhaps I will do some digging.

The Mundorfs I'm sure are plenty good!

[Paul Joppa]

Most cap companies make a wide variety of electrolytic caps. It is worth the trouble to find the specifications of a candidate capacitor even if the manufacturer is generally well thought of. As far as specs go, I look for temperature (85C is OK, 105C is better), rated lifetime (multiply by 4 if they are 105C rated), and low ESR at 100kHz.

Modern designs give low ESR at high frequency so they will not blow up in switching power supplies, but that's good for us too. The caps remain capacitive rather than resistive or inductive well past the audio range, unlike older designs where many caps become inductive as low as 10kHz. Incidentally, this is why AFAIK bypassing electrolytic caps first became popular.

Of course, subjective sound seems to involve more than just the specs. The Panasonic TS-xxx series of snap-in electrolytics have had an enviable reputation for a long time, so we have mostly used them in areas where they can affect the sonics. I'm sure there are others that are also good. We may be finding out, given the turmoil and unreliability of suppliers during this recession.  :^)

[coca]

FWIW, I think one has to go a long ways to find an electrolytic cap to better a pansonic ts-xxx sonically. At least that has been my experience.

Bernie D.