Can anyone tell me what type of resistor this is?

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Explorerman
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Can anyone tell me what type of resistor this is?

Post by Explorerman » Thu Nov 05, 2020 9:02 pm

Hi, I’m about to embark on a 2204 50 build and am looking at my current stock of components before I order the majority from VS. I have a whole bunch of 1/2w resistors in our old electronics spares (possibly from the 80s or 90s - I have no idea), but they look like they are carbon comps. I cracked one open to see the construction of it and you can see a spiral film under the outside crumbly material. Can anyone tell me if these are carbon comps or if they are something else? I’m looking to put some in the 50w build in the suggested locations in the 50w instructions.

Also, if these are some kind of hybrid carbon film resistor, would they be suitable to include in the build (noisy?) or should I get some Nos AB or carbon films? Thanks!

https://www.dropbox.com/s/8dswk7xrpcqem ... m.png?dl=0

danman
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Re: Can anyone tell me what type of resistor this is?

Post by danman » Fri Nov 06, 2020 6:35 pm

They appear to be carbon comp. I have tried using a few in my Marshall type builds and I always rip them out. Carbon comp will elevate the noise floor slightly and I can't hear any difference in the tone when using them. If you are dead set on trying some, purchase new production carbon comp. The Allen Bradley's that VS sells are NOS stock but new production resistors will certainly be quieter than older versions that have been in storage for years.

FWIW, Marshall used Piher carbon film resistors in their early amps and then switched over to Iskra carbon films in the 70's. You can find these on Ebay but they are quite expensive and hard to get these days. Most hobby and boutique amp builders use The 1 watt carbon films sold at VS. They work great and will certainly leave you with a quieter amp.

Explorerman
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Re: Can anyone tell me what type of resistor this is?

Post by Explorerman » Sat Nov 07, 2020 7:04 pm

Thanks mate, yeah I’ve read the nos ABB CC’s can create noise. Maybe I should stick with the VS CF’s. Just checked ebay for iskras CF out of curiosity and you are not wrong! There’s no way I’ll be paying those premium prices, surely there can’t be an audible difference in the manufacture of resistors worth the extra $$, coupling caps I can understand.

It’s been nearly 2 years since I was on here with various questions about the 2204 and 1987 and at the time planned to build the 2 in 1 on the SDM site. In the meantime, I’ve built an 18w TMB with JCM style pre-amp and power amp scaling, this thing sounds awesome even at home levels. But still really want to build a Metro spec 2204, and looking to re-visit this as a new project.

danman
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Re: Can anyone tell me what type of resistor this is?

Post by danman » Mon Nov 09, 2020 6:22 pm

I have built several of these circuits and did spend the extra money for Piher resistors a few years ago when they were a bit cheaper. I have also built them with the standard CF from Valvestorm and I can't hear any difference. I like to look at what the big name boutique builders are using in their amps, and many seem to be using the standard Xicon 1 watt carbon films that you get at Valvestorm. Good luck with the build!

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