Signal caps on the Trainwreck

[dms]

Hi - I can't recall where, but I thought I had read about the real wrecks using some type of brown colored (not orange drop, not Mallory) signal caps. Does anyone know what these caps might have been and who made them, etc.? Assuming they can't be found, what are people opting for? The Komet's use Mallory 150s, and I'm not sure which Sprague Orange drop is the part# of choice (the Two Rock guys said theirs were custom/proprietary, but did mention the Sprague 418 - not sure if the 418 is the one people use).

thanks, Davids

[Wayne Alexander]

I used Sozos, which are similar to Mallory 150 in "type" of sound (less harsh/bright than the polypropylene 715 and 716 series Orange Drops) and based closely on the old Mustard caps that were used in 60's Marshalls and Voxes.

[gnugear]

I've got soZos in my Marshalls but I'm trying the 716 series Orange Drops for my Wreck build.

[Allynmey]

I'm using Sozo caps and Kiwame resistors in my Board. I'm using Sprague Atoms for my power supply.

Allynmey

[mobisimo]

Little off topic, but how do the kiwame's differ from xicon or koa carbon films? Worth the money?
Back on topic, Mallory 150s seemed like the best cap for the money. I ordered those for my 18, but I am currently having to split between them and 715s because mouser had limited stock of the 150s. Alas. Swapping the rest of the 150s in when they get here. Maybe I should get some Sozos. That said, how do they differ from 150s?

[Dai H.]

IIRC, the "Kiwame" Rs are silicon-coated carbon film which come in 2W and 5W (might have been manf. by KOA also). The 2W ones are physically small for their 2W rating and have long leads.

[Wayne Alexander]

To my ears comparing an amp full of Mallory 150's to the same amp full of Sozos, the Mallories will sound a little less clear and focused, the Sozos sound pure with lots of harmonics. It's subtle, much less difference than, say, between either of those and the normal Orange Drop 715's or 716's, which are polypropylene and sound to me much harsher and brighter and brassy by comparison.

[dms]

Hi - I'm still wondering about the Sprague "418" orange drops- they are polyester film/foil (as are Sozos, Mullards, Mallory 150s) and were mentioned to me in passing by the Two Rock guys as a better choice; the SBE spec sheet mentions audio amps as an application for the 418. Unlike Sozos, etc. the Orange Drop 715/716 series are polypropylene and the corresponding spec sheet doesn't reference audio amplification, but rather "high pulse/high current applications where high frequency operation is required." I have heard comments about the brightness/sometimes harshness of 716 - makes me wonder why the 418s are not the more popular choice for orange drops. Anyone ever use them?

Still hoping one of our original Wreck owners will share some info on the brand/type of caps used in the signal chain... :)

Thanks, Davids

[gnugear]

Do the 716 Orange Drops have the same harshness as the 715, or are they a little smoother?

[Jackie Treehorn]

I did a quick little experiment using some aligator clips to clip in a well broken in Mallory 150 and a fresh 716 between the source and amp on my hi fi. To my ear, the 716 does not make the source brighter, but sounds very close to no cap at all. The 150 sounded far worse, rolled off highs, less and less distinct bass, worse transient response. So I don't think the 716's are bright, it's that the Mallories are dull!

However, if you WANT some extra high frequency roll off, the Mallories would be a good choice. I think one pays a price in transient response and mid range quality. With a 716, one could just roll off a bit of highs between the plates of the phase inverter, if needed.

It's probably better to try them both and see what works best with ones guitars and speakers. I'd rather hear the guitars and tubes, so I like the transparency of the 716's.

[Mark]

In discussions I've had about Trainwreck amps and caps. I'm told that some Trainwrecks were built with 715 caps. I believe the Dave Funk amps were built with Sprague 418's.

The cap that Ken Fischer prefers for his amps are polyester caps. I think the orange caps in his amps are orange Mallory caps.

I suppose it is questionable how different they would be to Sprague 418's 225's or 6P? caps.

It is also important to note that Komets are built with Mallory 150 caps. Are these caps Ken Fischers latest favourites?

The Sozo caps could also workout quite well in these amps.

KF also prefers Mallory electros too, though I have never compared the difference in tone between Sprague Atoms and Mallory supply caps.

On the question of resistors, the resistors he used were carbon film. There were the standard half watters.

I hope this helps

[geetarpicker]

My original '89 Express has 715 orange drops. I seem to recall my Liverpool also had them, but I don't own that one anymore.

EDIT: sorry guys, I don't know why I thought this back then. Later I looked and realized my original '89 Express has Mallory PVC caps for sure...

[Mark]

Dear Geetarplayer

Thanks for the reply. It's good to hear this sort of thing as it gives us some sort of time line as to when KF used these caps.

I do wonder how different an Express built with polyester caps would sound compared to an amp like your one built with 715's.

I do recall some time ago several guys at Ampage built Tweed Bassman amps, one with 715's and the other with poly caps. They said the poly caps won it hands down. Perhaps you could get the same sort of outcome from the 715 as the poly caps with a small cap across one of the plate resistors?

Anyway..........

[geetarpicker]

I know this is a late reply to this thread. I had my '89 Express out on the workbench setting the bias on some new tubes. Boy, you really can set an Express hot and still not have the tubes red plate on you. I guess the 400v or so B+ makes the amp quite able to handle a wide range of bias settings. More like, adjust by ear to taste. I settled on 50ma per tube, which was about 33v bias. Sounded good at that setting, and the tubes seem fine. Higher bias than you can get away with on a Marshall or something with the 450-500B+ or more.

I noticed the caps were of the same variety as Francesca, Mallory PVC601's. Not sure why I had it in my head for years that there were 715's in there. Anyway my Express is very very close in spec to Francesca, except mine was one of the first with the new transformers. Actually mine had a defective PT originally, but was later discovered that Ken had an entire batch that needed to go back. Bad internal solder connections on the heater windings/leads. Caused intermittent noises that were hard to trace on my Express, but were eventually fixed 100%.

I remember on my Express there sometimes was a little instability causing some HF oscillations. The fix was just a tiny bit of foam rubber stuffed under the board where the primary leads went under towards the OPT. The leads needed to be pressed down tight against the chassis, then it was cool even with all the knobs maxed.

Fired her up tonight (Orphan Annie) into two '68 BW 4x12s stacked and she sounded sweet!