Original high quality potentiometers, tube sockets and input jacks for JCM 800 2205

[jalexquijano]

Just scored a 1989 JCM 800 2205 (Split channel) and would like to know what upgrades besides the Mercury Magnetics output transformer should i make i.e. Potentiometers, input jacks, tube sockets, etc. Which supplier? I want to reduce the background noise. The amp sometimes picks up interference and would like to get rid of it. Maybe some of the WIFI signals or else.

[Tom Phillips]

Just scored a 1989 JCM 800 2205 (Split channel) and would like to know what upgrades besides the Mercury Magnetics output transformer should i make i.e. Potentiometers, input jacks, tube sockets, etc. Which supplier? I want to reduce the background noise. The amp sometimes picks up interference and would like to get rid of it. Maybe some of the WIFI signals or else.

It can be difficult to resist jumping right in to upgrades but ...
Excessive background noise is usually dirty parts and possibly a bad tube or two. It would be unusual for any of the parts you listed to need replacement. The first approach to service for the amp would usually be inspection and cleaning including treatment of the jacks, pots and tube sockets with the appropriate cleaner / lubricant / preservative such as Deoxit D5. Also re-tensioning of the tube sockets as needed. Parts replacement would only happen if a part was found to be damaged. In a blind hearing test the OT change may not even be noticeable. Usually, people just convince themselves that the amp sounds better because they spent a lot on the MM transformer.

So...I would not recommend changing any parts until you find a specific reason to do so.

Cheers,
Tom

[drewl]

The solder connections for the pots may need to be re-flowed and clean them as suggested.

[mhuss]

Usually, people just convince themselves that the amp sounds better because they spent a lot on the [fill in the part].

Ain't that the truth...

[Mick Bailey]

I've found over the years that noise in amps can be down to the location, and not necessary down to anything being wrong with the amp. Wi-Fi, phone, fridge, aircon and other noise is more usually picked up by the guitar. So the first question I usually ask is "does it do it without the guitar plugged in, or with the guitar volume turned to zero?"

The amp worked fine when it left the factory, with the pots, transformers, sockets caps and everything else that was fitted. Marshall jacks are usually perceived as plastic=low quality, but they're reliable and rarely need replacing unless damaged. Find out if there's a fault, or whether something isn't right. If you have a fault and replace the pots and transformers, you're still left with a fault. Swapping stuff out instead of troubleshooting is an expensive road to nowhere.

If you had a misfire on your car, would upgrading the wheels fix it?

[Tone Meister]

I have lots of personal experience with the 2205 Marshall heads. I toured a quad of these amps through the 80s and 90s and overall tone and functionality is best achieved by regular basic maintenance, using selected tubes (especially V1, V2, V3 preamp tubes), and most importantly speaker choice.

Speaking to the output transformer, if your amp has a functioning Drake OT then no aftermarket transformer you can buy will improve the tone in the slightest, no matter how much $$$$$ you spend. The 2205 is a two-channel amp and its Boost channel has a cascading gain which will almost always have some background hiss at moderate gain levels and above, even if you install the finest preamp tubes money can buy. That hiss is to be expected with that type of high gain circuit. Poorly functioning preamp tube(s) are a likely culprit for other types of excessive noise and/or picking up environmental RF signals from who knows where. As Mick said, sometimes an amp will pick up stray noises in some places and not others and a high gain amp is more likely to do so.

If the amp were mine, I would have it serviced by a pro and fitted with all new Tube Amp Doctor 7025-WA preamp tubes and Tube Amp Doctor EL34-B power tubes selected for high headroom. Selected Ruby tubes are also an excellent choice for tone and reliability.

My opinion is the Celestion G12T-75 is the worst speaker match for the JCM800, unless you like scooped mids and over-the-top treble response. Match it with a cabinet loaded with Greenbacks or Vintage 30 speakers and you're done. And finally, unless something on the amp is broken or not working, I'd just do the basics and call it a day.

The 2205 is one fine amp and there are times when I miss mine. Please don't hack it up.

[jalexquijano]

I have lots of personal experience with the 2205 Marshall heads. I toured a quad of these amps through the 80s and 90s and overall tone and functionality is best achieved by regular basic maintenance, using selected tubes (especially V1, V2, V3 preamp tubes), and most importantly speaker choice.

Speaking to the output transformer, if your amp has a functioning Drake OT then no aftermarket transformer you can buy will improve the tone in the slightest, no matter how much $$$$$ you spend. The 2205 is a two-channel amp and its Boost channel has a cascading gain which will almost always have some background hiss at moderate gain levels and above, even if you install the finest preamp tubes money can buy. That hiss is to be expected with that type of high gain circuit. Poorly functioning preamp tube(s) are a likely culprit for other types of excessive noise and/or picking up environmental RF signals from who knows where. As Mick said, sometimes an amp will pick up stray noises in some places and not others and a high gain amp is more likely to do so.

If the amp were mine, I would have it serviced by a pro and fitted with all new Tube Amp Doctor 7025-WA preamp tubes and Tube Amp Doctor EL34-B power tubes selected for high headroom. Selected Ruby tubes are also an excellent choice for tone and reliability.

My opinion is the Celestion G12T-75 is the worst speaker match for the JCM800, unless you like scooped mids and over-the-top treble response. Match it with a cabinet loaded with Greenbacks or Vintage 30 speakers and you're done. And finally, unless something on the amp is broken or not working, I'd just do the basics and call it a day.

The 2205 is one fine amp and there are times when I miss mine. Please don't hack it up.

Thanks Tonemeister. Well today i damaged preamp socket V3 while cleaning and now the reverb is not working. I accidentaly damaged one of the teeth of the socket while tnesioning. Do you know which is the best quality as replacement of all 5 preamp sockets?

Jorge