Going into Marshall to collect my amp tomorrow. Service and cap replacement $100. Factory tour booked for 10.00. Only live 20 miles away. Luck. Plus, used to supply transistors to them back in mid-90’s, when I bought my amp (direct). Long overdue visit. Great posts. Love these in-depth reviews. 👌🎸🇬🇧📺
C4 and C5 - 470p and 1n are standard Marshall JCM800 values, but it's all up to the customer what they want, but I personally would recommend both it if people want "Cut" and not be buried in the mix. In a recent Tone Talk last week or week before Dave Friedman actually said he preferred the 4n7 cap (ala Rhoads)!! It's pretty shrill, but again, what the customer wants and tech's opinions. I love cut, so 1n or 4n7 are musts for me. 470p is not enough and would never remove it and lose the cut. Looks like you doubled up the 10k's on the cold clipper resulting in 5k to change the bias point and increase the gain in that stage! This is late-80s JCM, so an improvement is splitting the screen cap can, so there are 5 B+ nodes instead of 4, which Jason Tong outlined in one of his Headfirst videos.
Good work Lyle, another great educational video. I noticed the 0.68 over V2a. I sometimes install a 0.33 cap here to emulate the previous stage 720Hz boost. Similar boost but in a different part of the circuit, but to me it seems to lower the noise floor when installed on V2a.
Lyle, if you want to experiment with voicing a PCB-based amplifier and expect to try a half-dozen components of various values, why not avoid pulling the board more than once by installing 1/2"-tall Molex or Amp-type header pins of the type with a plastic base-strip to keep the pins in vertical alignment, and solder the experimental parts to those pins? You can tacksolder the parts for experimental tweaking, then hook or wrap the leads of the final select, tonally-appropriate components snugly around the pins before soldering. This way, you won't have to pull the board a second or third time.
My take is that current production tubes are the problem that you correctly know the fix for . The production from 50 to 80 did not have the heater problem thus Marshall design was not bad at the time . Therefore the problem is current production tubes not the Marshall design . I do agree that the price of NOS is too much and elevated heater does do the trick . As you have seen here products are designed with what was able to be had at that time . Source of the problem is academic to make it go away is the sign of an artisan and a fine craftsman. Regards
Do you take amps from Florida? I have a 1990 JCM 800 Super Lead that was modded by Schur which sounds good but is a bit too gainy and compressed for my taste. I'm just trying to get it back to loose clear Marshall tone while leaving the master volume. Any insight would be appreciated!
You're 2 years off too, Andy... the 2203 filtering change came in late '85 in conjunction with the horizontal input jacks now being directly mounted to the pc board. '83 was still vertical input jacks.
@@AndyK.23 You must mean after late '85 were horizontal inputs on both 2203/2204. This may seem like semantics, but is an important factor in determining when Marshall changed the 2203. There's always a transition period when changes like that are made, but generally any horizontal input 2203 is of the "new and improved" neutered variety. You are correct in that the 2204 didn't have any cut-corner, cost-reduction "improvements" in the power supply like the 2203 did. Just the jacks. Regards 🎸
I never know that the later models had one less filter node. I just looked at a couple of schematics on the Hoffman site and I did not see the missing node.
good evening, first of all, congratulate you for your excellent and very illustrative video, I am writing to you from Colombia, I am in the project of making a clone of this amplifier (marshal jcm2204) but I do not have information on the input power transformer, it is possible that you Help me with the technical information of the transformer to have it manufactured here in my city, thank you
