JCM 800 4212 Combo

[musicman]

I'm currently watching 2 of these on ebay.

50w 2x12 with clean & overdrive, separate eq, spring reverb, master volume.
2 channels appeals to me especially as the "clean" channel is said to break up to early Zep sort of tones.

Anybody got any thoughts please ?

[surfnorthwest]

I am pretty familiar with that amp, it is a two channel combo with 50 watts with a extra gain control. They were very popular back in the 80s and with the right tubes and speakers set up they can be very loud. A good amp with good headroom. I know there has been a lot of reliablity issues with them though also. If you can get a good deal get it, the only thing those amps need is a good eq pedal, the natrual gain from those is sweet.

http://reviews.harmony-central.com/revi ... +4212/10/1

Still my favorite and best sounding Marshall combo is the JCM TSL 602

[musicman]

Thanks Surf,
What sort of reliability issues please ?

[surfnorthwest]

Channel bleeding was just one I really remember.

[musicman]

OK thanks Surf

[ClubAndCountry]

They are not reliability issues - like all JCM800s, they're built like tanks and almost never break.

But there are some performance issues, eg the bleed-through from the distortion channel into the clean - which affects some but not others. There are three different versions, which all look identical from the outside. The best is the earliest, which has less gain but a fatter tone, and also has a post-phase-inverter master volume, like the Vintage Modern. The gain only really kicks in right at the top of the turn on both the gain and channel volume, so some people think they aren't working right, but it's just the way they are. These were made from 1982 until 1984. The second version from 1984 to 1987 has more gain and a more even control range but a buzzier tone and is the one with the worst problem with bleed-though. The third version from 1987 to 1990 is similar-sounding and with the bleed problem cured. Some people like the sound of this one the best too, but I think it's the most solid-state-like and buzzy.

You can identify the versions if it's from 1984 or 1987 - open it up, and have a look for either a dual-gang master volume pot (1st version) or a switching chip (3rd version).

The only actual reliability issue I can think of with them is that the reverb valve (position varies depending on which version) is run at such high voltage that weaker types quite often fail, particularly Sovteks. They're also all getting a bit old now so you can probably expect electrolytic cap failures sooner or later, although mostly JCM800s aren't quite at that point yet. For some reason the type of pots they used seem prone to going badly crackly too, but you can fix that with some contact cleaner/lubricant (possibly more than one attempt!).

[musicman]

Thanks ClubandCountry.
The one I'm looking at is a 1986 version with Drake Transformers.
I've asked the seller if there are any scratchy pot or bleed through issues and been told No - everything works as it should.

[ironlung40]

careful on the "No bleed through" as it is sometimes only noticeable at high volumes. In 86 or 87, these amps went through a circuit change that eliminated this problem, yours may very well be o.k.