JCM 800 KIT?

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dd3keegs
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JCM 800 KIT?

Post by dd3keegs » Wed Apr 05, 2017 10:15 pm

Hey. I've taken some of the forum member's advice and started small. My first build was a single channel Class A 5 Watt Hi Octane amp from AX84.com. I then built The same amp with and extra gain stage. Then moved up to Fender Tweed 5e3 clone. Now I think I'm ready for a JCM80O CLONE with an Extra Gain Stage and Depth Mod? Silly question...but does Metro amps sell this as a kit? I already have a empty Head cab with 2 matching Closed Back1 x 12 cabs loaded with Celestial Vintage 30s. I also found this wiring diagram online. Is their any other BOM or wiring schematics or diagrams that are better? ANY help would be appreciated. Thanks.

danman
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Re: JCM 800 KIT?

Post by danman » Thu Apr 06, 2017 5:00 pm

Valvestorm sells kits that are based on the Metroamp kits and layouts. Here is the page for the 2204 which is the predecessor to the JCM800...http://valvestorm.com/2204%20Kit You basically build the kit from their 50watt checklist and instructions and add in the couple of extra bits that you need. The regular 50watt and the 2204 circuit are very similar except in the preamp. The 2204 has a cascaded preamp which gives you the extra gain. You do have to buy your own transformers which allows you to use what you prefer. The Metroamp, Marstran and Classictone trannys are all very good so it's up to you want you want to use. I will mention that the early 2204 circuit ran a much lower B+ (around 370-390vdc) than the later JCM which was up in the mid 400s. Some people prefer the warmer, earlier breakup of the low voltage model and some prefer the brighter, punchier nature of the later high voltage models. If you have any question, just email Valvestorm and he will get you the answers you need.

danman
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Re: JCM 800 KIT?

Post by danman » Thu Apr 06, 2017 5:11 pm

I just noticed on the Valvestorm site, where they list the transformer part numbers from different manufacturers, they have the classictone PT and OT part numbers mixed up. The standard PT is 40-18089 and the OT is 40-18025. Classictone also offers the 40-18054 PT which has a high voltage secondary (450v) and also a low voltage secondary option (about 410-420v). This PT allows you some flexibilty in your final B+ voltage. Just be aware that the chassis that Valvestorm sells requires a laydown PT and not the upright style...http://valvestorm.com/Transformers#50watt

danman
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Re: JCM 800 KIT?

Post by danman » Thu Apr 06, 2017 5:15 pm

I wrote all that and then realized you may want to build a 100 watt model instead of the 50 watter. Either way, they have what you need for the bigger amp also.

dd3keegs
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Re: JCM 800 KIT?

Post by dd3keegs » Thu Apr 06, 2017 7:09 pm

Thanks so much. I've checked out Weber, Tritone and Mojotone. This looks like a good kit too. :toast:

danman
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Re: JCM 800 KIT?

Post by danman » Fri Apr 07, 2017 9:32 am

Valvestorm took over the amp kits when Metroamp stop selling them. He is also a member here so he can help with any questions you may have. Any of the parts on his BOM with the letter "M" beside them are what was used in the original Metroamp kits. You also have the option to order the vintage NOS parts instead if that's what you prefer.

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neikeel
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Re: JCM 800 KIT?

Post by neikeel » Fri Apr 07, 2017 5:28 pm

I think you will find the Valvestorm/Metro project a much better quality and more true to the originals than the other kits, most people get stuck half way through with the others and then toddle along here for help!

Build one true to the originals with correct wire colours. The Classic tone trannies appear to be good value but they have odd wire colours.

A 2204 is a very usable amp with great tone when set up properly.
Neil

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Re: JCM 800 KIT?

Post by fixer2 » Wed Jul 06, 2022 2:13 pm

Hi I purchased the stuff from valvestorm to make there 100 master volume kit how much if any is this different than a JCM800 10” watt Marshall I know Marshall made jmp in the late 1977 or 1978 that were 100 watts and had a extra gain stage that the 50 didn’t until the 1981 JCM800 50 . I want to build a jmp 100 with a extra or two extra gain stages . We’re could I look for a layout or guidance.

Asphaltbouncer
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Re: JCM 800 KIT?

Post by Asphaltbouncer » Wed Sep 07, 2022 10:22 pm

Very cool idea.

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