18Watt.com

Hey Guys,

I need yall's indispensible advice on new old stock caps and resistors before I spend $75.00 on a set to outfit a new JTM45 I am about to build. Is there any noticable difference in tone between the NOS and current stock? I have been told that NOS caps and resistors "crackle" in humid environments and are more prone to hum and that the trade off in tone is negligible. I must admit that I am partial to their appearance, they make for a sweet looking board. Would my money be better spent on a handwired, custom set of trannies?

Won't make a decision without yall's advice. Thanks, Rock On.

Sean

Hi Sean,

If you've got $75 to spare, I say you buy the NOS supplies, build your amp, then take copious amounts of photos and post 'em here for us to drool over.

Here's the good part - if you don't like the tone/noise/sounds you get, take 'em out, put in the new stuff and THEN record us some samples. No one's the wiser!

Dean

I used NOS Allen Bradley CC's in my Tweed Deluxe and the results were good but since reading up a lot more I'm leaning toward Jeff's strategy. I got the parts for the Deluxe from Mike Clark and I think he screened out some of the bad ones because the ones he sold me were all within spec.

I don't think I'd consider NOS caps. There's too much good stuff available. If I wanted to go for broke I'd use paper in oil signal caps from Angela before I'd risk old ones.

It would make a nice looking build but I've replaced too many caps over the years on my day gig to want old caps in my new amps.

$.02 from a tech

Paul captured my philosophy as well, except I would avoid the CCs altogether unless I was desperate for more mojo.

I totally agree with gtrmac - caps are one thing NOT to buy NOS. The metal flim caps we could debate about, but electrolytics - no way! I won't even buy LCRs anymore unless they have 98 or 99 datecodes.

NOS tubes are excellent, and generally do not go bad with age. Everything else is suspect in my book.

--mark

I was reading some tech data the other day, from a cap manufacture. Think it was mallorys site. Anyway, the electrolitics seem to have the shortest shelf life. And it depended on the cap rating. The higher the temp rating of the cap the longer shelf life. 125 degree caps being the best or longest.
As for the other caps. What they described was where they may be stored, and type,but most of them could be fine for 20 years {storage in a dry place} Now as with NOS or new, you can see bad in any of them, i guess they can slip by. It also showed the life expectancy of the caps in hrs of use. Or abuse..lol
I wish i had kept the link, it had some great info.
Richie

Thanks Guys,

I am gonna spend the $ on a custom set of trannies from Handwound Transformers instead of spending the loot on the resistors. Hey I can always rob some Testors model airplane paint from my son and paint some new ones in mustard yellow, purple and green. Then I can pass them of to some the guys in our group as NOS for $75.00 a set huh? Rock On.

Sean

I wouldn't buy NOS aluminum electrolytics, but film and oil maybe--depending on what they were. Like the old Philips "mustard" caps (commonly found in Marshalls and other British amps like Hiwatt, Vox, etc.), for instance, seem to have held up and hold up fine (i.e. don't leak DC). The old Sprague Black Beauty and similar types like the CDE Black Cats--they sound good to me but I wouldn't buy them unless I could get a bunch really cheap (so I could sort out the non-leaky ones and have multiple backups--I've got one that is shorted internally too to give an example of another defect you can encounter) or maybe a tested one. But even then, I wouldn't feel comfortable putting them in someone else's amp (but maybe my own) because I'd have doubts about reliability over time. The Sprague Vitamin Q and similar hermetically sealed oil caps don't seem to leak while just about every old Japanese (non-hermetically sealed) oil cap (usually blue or gray covering) leak or develop leakage. So you couldn't use those in amps but for a different application (like inside your guitar for the tone cap--no voltage on it--or insignificant voltage), they should work (so don't throw them away automatically). Carbon comps seem okay as long as they're stored well and not overheated (circuit overload or sloppy lingerting-too-long soldering I would guess are some of the cause for "bad" carbon comps). I have a huge bunch of old Japanese 1/4W 51k c.c. which were apparently stored poorly and the tolerances are all over the place (don't feel comfortable using those), but I've also got a bunch which were apparently stored well (in the original plastic packaging with some having a bag of silicon dessicant inside) and have held their tolerance. I think the whole signal chain *as a system* is important, but if pressed, I would say, make sure you get good transformers, speaker(s), and tubes, and the rest should be fine with readily obtainable parts like the Mal 150s, Sprague ATOMs, carbon film, or the Xicon/Kamaya carbon comp, etc.--get one of Paul's turret boards (or someone else's equivalent item) to make it easy to change parts and you could experiment with the caps and resistors later on if you wish/as you get more money.

Dai

Sean wrote:Thanks Guys,

I am gonna spend the $ on a custom set of trannies from Handwound Transformers instead of spending the loot on the resistors.

Expect a LONG lead time for those transformers. Folks have just received deiveries in the last few weeks for trannies ordered at Christmas time.

Just FYI...

I have both Heyboer trannys in stock right now for immediate delivery. These are made to the exact specs of the original Radiospares trannys but with 120V/240V primarys so that they can be used here in the USA or in the rest of the world. I even have a few PTs with 100V taps for the guys that live in Japan.

See my parts ordering page for pricing.

http://elektro.cmhnet.org/~graydon/18wattbuyparts.html

Sean's looking for trannys for a JTM-45 clone. I see Graydon lists JTM-45 power tranny and choke but no listing for output tranny. I guess Mercury Magnetics or OEI have offerings for the output but the new OEI is not due to ship until mid-July.

Mac and Sean,

I have alwyas been tolerant generally of off-topic posts, and the JTM45 is really not that far off topic anyway, so we let this one slide.

You are correct, I do not sell an OT for the JTM45. The OEI and MM OTs are shrouded by lots of mojo and reputed to be the best so I felt no need to supply my own version of that OT. My JTM45 chassis is designed to accept the standard JTM45 trannys, so OEI or MM OTs and PTs will fit my chassis.