capacitors

[ronman]

Can I use mallory polyester film capacitors on a express build or should I use the orange drop.Every one says not to use the polypropylene but that is the one that most places sale.

[Colossal]

Can I use mallory polyester film capacitors on a express build or should I use the orange drop.Every one says not to use the polypropylene but that is the one that most places sale.

That choice will ultimately be up to you to make. The standard signal capacitor in the Express is the (now obsolete) Mallory PVC series polyester film foils. They are scarce now. Some guys use Mallory 150M, SBE 6PS series, or Sozo polyester film foil caps as a substitute. There are members here (Jackie Treehorn) who have used and like polypropylene film foil caps in the Express and Rocket (I think his amps sound really good).

The choice depends on the degree to which you are willing to go to build your Express amp; whether you are a "purist" and must a dead-on clone and will accept no substitution, or if you are ok with taking liberties with part selection, or just plain prefer the sound of different dielectric materials (polyester vs. polypropylene).

Here is a photo of the real deal:

[rooster]

Isn't Allyn ordering these in bulk from Sprague/Vishay? Can't you buy these from him then? I bought a few sets from him a few years ago anyway.

But now that I look around this site - is Allyn still here? I thought Omar handed over the reins to him but now I see no mention of that in the sticky. Man, what have I missed?

[My-Co]

Use your ears, What sounds good to you??

[sliberty]

I have used Mallory 150's and I have also used proper Orange Drops in Express and Rocket builds. Both will yield nice results. There are probably some minor sonic differences, but you would only really notice them in side by side comparisons with all else being the same.

[MikeSafreed]

For my last Express build, I used the Mallory 150's, and since I don't own another TW Express, I have nothing with which to compare the 150's. But, I will say that I expected the Express to have a lot of sweet tone, and a ton of dynamics, and this amp has both. I'm in the middle of another Express build, and this time, I purchased a set of the original PVC caps from RJ, so when I'm finished I will have something to compare against. I've been building amps for a very long time, and I've kind of put caps into a couple of major categories. Polyester's tend to be just a little grainy, and give you a tone that reminds you of a Fender Tweed circuit, and Polypropylene's tend to sound cleaner, more like a Fender Blackface (think Super Reverb or Twin Reverb). After reading the specs on the Mallory PVC's and comparing them to the specs of other caps, on paper they appear to be closer to a 150 than to something like a Sprague Orange Drop. But, in the Express I built, I don't hear that graininess, so there's a lot more to the tone of an Express than just the caps. Like someone earlier said, trust your ears. After a while, you'll learn that you can totally change the tone of an amp with a simple bias change, regardless of the caps. Bias it colder and the headroom increases and sometimes the amps cleans up, and even 150's can sound clean. Conversely, you can bias an amp hotter that is loaded with Sprague Orange Drops, and the headroom will disappear, and the amp will seem to thicken up and exhibit a warmer tone. Another consideration - there is kind of an inherent sequence of tone creators in an amp, and caps are pretty much down the list. Speakers, tubes, output transformers, and speaker cabinet construction all seem to have bigger impacts on the tone of an amp than do caps or resistors. I'm not implying that caps and resistors don't impact the tone. They do. Once you have a baseline of the best speaker(s), tubes, transformers and cabinet(s), then you can begin to tell the differences that caps and resistors can make... When a customer asks me to build an amp for them, and they start to cut costs with speakers and tubes and less expensive transformers, I pretty much know that I can use just about any type of cap and they'll never hear the difference. In the case of an Express, you really can't chinch out on the transformers, and if you use a tube like the Groove Tubes EL34M and a decent preamp tube set, about the only mistake you can make is to use junk speakers. And, if you're hip enough to build or buy an Express, you are also hip enough to know that you'll need good speaker(s). Since there really aren't that many caps in an Express, it's a good platform to use to try different types of caps. That way, you'll learn what your ears like best...

[Decko]

Hi All,

I was watching a video commentary by Ken Fisher and he was asked what made his Trainwreck amps unique. Ken responds that his amps were designed around two technologies: guitar amp technology and hi if technologies. He mentions using quality components such as silver mica and polypropylene caps.

That said, what cap composition did he use in the preamp? Or did he simply Taylor each amp to his customer?

Danny

[Colossal]

He mentions using quality components such as silver mica and polypropylene caps.

That said, what cap composition did he use in the preamp? Or did he simply Taylor each amp to his customer?

Danny

Danny,

Guys who knew Ken or have more intimate, firsthand knowledge may chime in and I hope they do, but did you hear Ken specifically say polypropylene in that interview? Because to my knowledge (admittedly limited), I thought the signal caps in Trainwreck amps were predominantly polyester (Mallory PVC series) and mica (Mallory).

Polypropylene caps are commonly associated with hi-fi amps because of their fast transient response, low distortion, and high stability across a range of temperatures. I have not seen a real Wreck with polypropylene caps but guys here (Jackie Treehorn) have used them in clone amps with good results. I used polypropylene in my test Liverpool and the tone is fantastic with plenty of low end. The amp is biased quite warmly.

Dave

[Decko]

Hi Dave,

Glen Kuykendal posted this video on youtube. I am sure many of you have seen it.

Ken Fischer of Trainwreck Circuits Interveiw Part 1

Put tht in the search bar on YouTube. Then slide over to 5:25.



"Back on June 6, 1992 my good friend Nigel Brewer had the foresight to interview the now late Ken Fischer at "Trainwreck Circuits" headquarters (Ken's basement amp workshop) in New Jersey. The full interview was edited down into 3 parts, and was originally shown on Nigel's "Rock Study" cable TV show which "aired" in Northern, VA. Part #2 of this interview was already posted here along with my spot on the TV show. So far the 3rd part of the inteview has yet to be found, but hopefully we'll eventually get all the footage together and uploaded. Note the 2 Trainwreck amps on the table in front of Ken. Other than this interview footage, I've never seen any other video of Ken Fischer. Enjoy! Glen Kuykendall"

http://www.glenkuykendall.com/

Danny

[Colossal]

Hi Dave,

Glen Kuykendal posted this video on youtube. I am sure many of you have seen it.

Ken Fischer of Trainwreck Circuits Interveiw Part 1

Put tht in the search bar on YouTube. Then slide over to 5:25.

Hi Danny,

Thanks for posting that. I have seen those videos before (thank you Glen) but it was a long time ago and I overlooked that particular statement. Indeed you are right; Ken says polypropylene. I am wondering if there are TW amps out there with PP caps. I sure wish we could see an archive of gut shot photos from some of his other amps. I'd like to know how many component variations Ken actually made when he tuned amps specifically for his clientele. I guess we most often think of an Express as a hard formula of Mallory PVC polyester signal caps, Stackpole carbon film resistors, Mallory TC series power caps. I know Ginger used what look like brown drops, but I don't know what flavor of dielectric. I know this is obsessing over minutiae but I'm interested in Ken's methods and line of thinking. In speaking with some people that knew Ken, they said he was incredibly resourceful and even used transformers from discarded televisions when he saw fit.

Thanks to Glen for posting those videos.

[Richie]

the last half of the caps in a Rocket are polypropelene. Some amps used other brown CDE caps. And some PVC mallory were brown and some light blue.

[Colossal]

the last half of the caps in a Rocket are polypropelene.

Wow, very cool Richie. I just checked the Rocket BOM and you are indeed right.

[Clyde]

you'll need good speaker(s).

I don't mean to hijack the thread but I'm just wondering what you like Mike.
Thanks.

[Markusv]

Not sure if this was inadvertently addressed above:

I get all my caps from Just Radio's in Toronto. Great outfit and great quality. (no association of mine)
http://www.justradios.com/capacitors.html

They have 2 types of Polypropylene:
1) Polyprop Film Foil in an OD form
2) Metalized Polypropylene in a yellow tubular axial format
They also have Polyester pf caps that I love

Of #'s 1 and 2, the Metalized PP seem smoother to me

Any insights as to the "film foil" vs "metalized" effect?

Thanks
Markus V