Output Coupling Capacitors

[Paully]

I was toying with the idea of using these when I order mine:

http://www.diyhifisupply.com/catalog/34

Obbligato PSU caps.

[Doc B.]

Dueland CAST-PIO, 40uF. You would probably want two in parallel for each channel. At $2,581.00 each, they seem like a total bargain.

[Grainger49]

Isn't that at, or beyond the point that we can call it Gilding the Lilly?

[Jim R.]

How about we just call it obscene :-)

Sure, I'm guilty of buying some boutique parts, cables, etc., but this just seems a bit too far out there.  Then again, I guess it's all relative to your situation.

-- Jim

[Grainger49]

Jim,

Obscene is good!  Seems that PIO caps like these are priced like Teflon caps.  Although Teflon caps are not available in 100uF.  Not any thing close that I have seen.

[machinehead]

@Doc, gotta love it!  $5k for caps..... I have read much about the Duelunds, and I am sure they are the best you can buy, but....really???!!$5k?  I gotta start winding my own!

Love the new kit, almost ready to pull the trigger on one!

Here are some vintage Mallory 100uF 250V, it takes a bit for the page to load then scroll a ways down:

http://www.vt4c.com/shop/program/main.php?cat_id=2&group_id=1&hit_cat=

[Grainger49]

Although that link says, "Paper Tube Electrolysis Capacitor,"  I feel sure they meant to say Electrolytic.  Most old electrolytic capacitors are leaky.  And I don't mean physically.  The electrolyte is drying up and they are not as good as they were when made.

Maybe these Mallory caps are different?

On second thought these caps might have been used for electrolysis after all.

[roger_s]

My Axons arrived today.  Not very scientific but I downloaded the jpg of the underside view and zoomed it up via Preview.  Best I could do was about 5.75"; close enough.  Holding one of the caps to my monitor it appears that they'll fit just fine.  They'll fit better without that terminal strip adjacent to the 6AS7. 

I ordered some of the Axons yesterday, and I'll let you guys know how we end up fitting them in. We also put C4Ss with BIG heatsinks on the 6080, so it may be a bit of a tight fit in our prototype.

[Paul Birkeland]

You could hop on over to Radio Shack and buy an extra 5 lug terminal strip, then add it to the 2nd bolt on the 6080.  Then the big honkin caps can fit between those two strips, with the caps tied between the outside terminals on the two strips.  I would jumper from the cathode pins of the 6080 (3 and 6) to the outside terminals of your added T-strip, then the wiring for the headphone outputs can be retained. 

You will, undoubtedly, have to bend the leads of the caps around their bodies a bit to get them to fit, but it should work fine. 

[Paul Joppa]

Quick note here - the last power supply capacitor is equally important to the sound IMHO.

[Jim R.]

And what would be the value/rating of that?  Will you be including a TSHA with the kit?

Also, can I ask how many terminal strips will be in this amp -- not including the extra one PB just mentioned?

-- Jim

[Paul Birkeland]

The power supply capacitors in the kit are the 220uf 250v caps found in the extended Foreplay III.  These are TSUP series Panasonics. 

There will be four terminal strips included with the kit: two 5-lug strips, and two 6-lug strips.

Although the quality of the last cap in the supply is quite important as PJ mentions, the value is also quite critical.  If it gets sized down much at all, the ripple becomes audible.  Of course, the ESR of film caps tends to be nice and low, so some experimentation will probably be needed to find a comfortable balance.

Incidentally, there is probably just enough room to squeeze a giant Solen cap between the 6-lug terminal strips that flank the power transformer.  I may need to trade in my ugly prototype for a fresh kit when the plates arrive...

[Jim R.]

Thanks, Paul.  I forgot to ask if there will be one or two of these PSU caps.  I'm assuming you're using dual supplies so as to balance the transformer secondaries on the PT-3, so I'm therefore assuming two big psu caps.

-- Jim

[Doc B.]

I may need to trade in my ugly prototype for a fresh kit when the plates arrive...

You may have to take a number. We doubled the initial chassis plate order and just ten days after introducing the kit we have only ten kits left from  the first run.

We got the Dayton film caps in yesterday and gave them an initial listen. While they sound clearer and cleaner it makes me realize that the stock lytics are pretty good. I think the C4S upgrade makes a bigger improvement than the cap upgrade. We will be figuring out an upgrade for the final cap next. The chassis is getting very crowded with all this upgrade experimentation...

[Doc B.]

Oops, make that only seven kits left from the first run. At this rate those will probably all sell this weekend. We will start a second run as soon as those sell, which probably means a lag of at least a couple weeks between runs. So if you're thinking about ordering a kit, today would be a good day to do it.