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Re: Tantalum VS. FILM!

6/15/1999 2:18 AM
Dave Chun
Re: Tantalum VS. FILM!
Allied Electronics ( has the 6PS and a small selection of 225s. The PS are supposedly exactly the same as the 418s. I've futzed around with different types of caps, and settled on 418s in the tone stack, paper in oil in the phase inverter, and 716 or 715s everywhere else (this is an SF Twin Reverb.) With this setup, I usually run the neck pickup of my Strat with amp set 7/6/4 (treble/mid/bass) for a balanced tone with some high end bite.
6/15/1999 3:44 AM

Hi Dave,  
I just checked the Antique Electronics online cataglog, they have plenty of the PS type. Did you actually find a 418P? I think it was Allied that I had checked but their inventory is sketchy at the time. Are you able to obtain the 418P's somewhere? I may go back to the PS, had been using the 715 and 716P's. I've got a 72 Twin, stripped out the board and will rebuild it one day to maybe something other than a twin. One of may projects down the road. Terry
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6/15/1999 3:51 AM

Guess my heads really foggy tonight. When I posted earlier I left out my email address, then I reposted and listed my email address but not correctly. The correct one is listed on this post above. That's like forgetting one's own phone number. Terry PS, on the subject of caps, anyone making or rolling their own? I want to experiment a little in that area. Might me interesting. I rolled one up about the size of a cigarette in about two minutes once just to show a friend and I can't remember the value but as I squeezed it the value changed (cause it wasn't rolled tightly) We got a good laugh about it but may seriously do some in foil rather than that sprayed on crap. Goodnight!
6/15/1999 1:37 PM
Dave Chun

I found 418s by sheer luck at a local surplus store. They had a few values, couple dozen each, so I bought them all. The only other "reliable" source I've seen for them is Torres Engineering - if you're only buying a couple, then the inflated price isn't that bad to swallow. Other than that, the 418s have been discontinued as a regular product on the line, so the only way to get them from SBE is to order in the 1000s.  
Never tried rolling my own caps. I've always figured it's cheaper, easier, and safer to buy them.
6/15/1999 4:00 AM
Steve A.

    I've been buying the 600V 418P's from Dan Torres (which have come down a bit in price since he has been trying to market them on the Web). I believe that he buys them in 1000 lots and has his name stamped on them ("Butchers'R'Us"... that's a joke!) Mouser sells the 400V 225P's which I believe are the same animal in a different package and at the lower voltage.  
    The 715P's are polypropylene while the 418P/225P's are polyester, which might explain the different results I've gotten when using the 715P's.  
Steve Ahola  
P.S. Speaking of Dan Torres, he was wiring up a custom amp for Lindy Fralin when I stopped by last month. His custom amps look and sound great (it's too bad that his "one size fits all" mods for BF/SF amps have given him a bad reputation on the Web... but they have gotten a lot of people (like me!) hooked on tube amp mods and designs.)
6/15/1999 4:24 AM

Hi Steve, I was about to sign off and scanned the board one last time. I'm down here in Florida and it's just past midnight. The Torres book was the first book on guitar amps that I purchased maybe three years ago. It got me started. Since then I've purchased several books both new and a few at used book stores, flea markets, ham fests, etc. I don't know why Torres has had such a bad rap. I've got no negative opinions on the man. I could never get an understanding of what peoples complaints about him really are other than the word "butcher". I will probably order a few of the 418's from him in the near future. I think his prices have come down because long ago, his parts were quite high in comparison to some other sources. Wonder why others don't carry the 418's though or why they are so hard to find? I'm an electrician (self-employed) and I'm used to chasing parts at times. It's frustrating to know that something is manufactured yet "no one" seems to carry it. I don't know what's the problem with SBE not answering emails, also the same darn thing with ART. Am trying to find out about the LCD in an SGX2000Express that doesn't light up. The lettering is readable but the backlight doesn't stay lit. I wrote to them two years ago, faxed them about two months later and recently emailed them and still no answer. Guess I will have to call them and listen to someones BS and hopefully get an answer or get them to send me the part (I'm willing to pay for it)rather than shipping the unit back. For a unit that cost over six hundred dollars couple of years ago, I'd have been wiser to invest into a good tube amp. Live and learn! Right? Past my bedtime, ha, ha. Bye, Terry
6/15/1999 4:11 AM

Technically speaking, I would call the 225P which you described a foil cap since the capacitor plates are made of thin foil. This may sound confusing since the cap is of the polyester film variety. A more precise way of describing what I referred to as a film cap would be the term 'metalized film capacitor' in which the film itself is made conductive by spraying an extremely thin coating of aluminum on it. If you ever see metalized film up close you will know what I mean. You can hold it up to the light and actually see through the metal. The metallic coating is that thin.  
In general, foil caps sound better than metallized film. However, there is a significant number of people who prefer metalized film over foil for the following reasons: 1) metalized film caps are a lot smaller physically than foil caps, 2) metalized film caps have lower temperature coefficients than foil caps since the metal plates of foil caps expand slightly when heated, and 3) metalized film caps tend to be self healing since a short across the dielectric quickly vaporizes the metalized area involved in the short, thereby causing the short to disappear.  
My preference as far as Sprague goes is the 715P Orange Drop which is a polypropylene/foil that sounds well balanced and is slightly brighter than the 225P but not objectionably so. A good inexpensive substitute for the 715P is the Xicon MPP series of metalized film caps available from Mouser (some metalized film caps actually do sound good!). If money is not an objection, then the ultimate capacitor, in my humble opinion, for enhancing high frequencies is the Musical Interface Technologies (MIT) Polystyrene MultiCap which is a non-inductive foil coaxial cap. Hovland MusicCaps and Kimber-Kaps also get high ratings and would be an appropriate substitute for an MIT.  
Thanks for your additional insites on caps. I always find the topic intersting.  
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