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NAD (last night) 1982 Marshall JCM 800 4010 Master Volume 50 watt 1x12" combo

Don

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Dec 1, 2001
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I've wanted one of these for a very long time! It's dirty on the outside, the pots were scratchy as heck, and it was making some odd noises and cutting out then sounding awesome, then cutting out again... I cleaned all the pots, jacks and sockets and replaced the preamp tubes and it sounds awesome!

I'm going to replace the 39 year old electrolytics and B+ dropping resistors for the sake of reliability. I may leave the ancient GE 6550 power tubes in it and just check the bias. It's tempting to change it over to EL34s for a more "authentic Marshall sound", but I've heard arguments that the 6550s sound fatter at lower volume levels and might actually be better for the type of blues rock that I play on an amp like this.

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39 year old electrolytics! Scary!

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K_L

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Sep 11, 2014
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I`ve had one of those for a few years now & absolutely love it. Don`t get a chance to crank it very often [because it is a loud 50w Marshall!] but really enjoy playing thru it`s Low Input w/ a nice distortion pedal. It will eventually become my grave marker.
4010 & 5010.jpg
 

mdubya

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Mar 31, 2010
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You won't find many that sound better than that one! :love:

I also doubt you will find any modern tubes that sound better than those old GE 6550s. I would run those forever unless you have a very good sounding set of old EL 34s.

Congrats on a truly classic amp. 👏
 

Don

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This amp sounds passable with the master at 1, better set at 2, and roars like a lion at 3!
 

Texas Blues

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If I recall AlvisX (Alvin Youngblood Hart) who is a member here also digs on that amp.

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Don

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If I recall AlvisX (Alvin Youngblood Hart) who is a member here also digs on that amp.

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Thanks a lot! Now I have to buy a Les Paul Jr! :)
 

Holgar

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May 11, 2003
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This is a great little amp and still in original condition! Please do not mod it - it does not become better. With an OD/EQ stompbox you can achieve anything.
If you have replaced the planned parts and the amp is still not ok, maybe the Ohm selector still makes problems. I have replaced two of them last year, because irregular noise have emitted. They are wobbly and the current runs through a tiny clip.
 
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Don

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This is a great little amp and still in original condition! Please do not mod it - it does not become better. With an OD/EQ stompbox you can achieve anything.
If you have replaced the planned parts and the amp is still not ok, maybe the Ohm selector still makes problems. I have replaced two of them last year, because irregular noise have emitted. They are wobbly and the current runs through a tiny clip.

Thanks! I have no plans to modify it. It's pretty great as it is now.
 

Don

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Do you guys think these made in Japan 12AX7/ECC83 preamp tubes came in the amp when it was new?

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K_L

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As I mentioned earlier, I have a JCM 800 50w 1x12 combo [4010 w/ the 2204 circuit] like Don`s & it is a great sounding amp, even thru the Low Input w/ a nice distortion pedal--classic tones either way! Last night, as a b-day & semi-retirement gift to myself, I ordered this--a 'used' model of the new 20w Studio Classic JCM 800 combo that has the ability to switch down to the lower 5 watt setting. All that I have read about these amps is that it is a great sounding amp so I look forward to it`s arrival next week. Hope you are enjoying your Marshall 4010 Don--they have great classic Marshall tones all day long! Stock photo.jpg
 
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Don

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As I mentioned earlier, I have a JCM 800 50w 1x12 combo [4010 w/ the 2204 circuit] like Don`s & it is a great sounding amp, even thru the Low Input w/ a nice distortion pedal--classic tones either way! Last night, as a b-day & semi-retirement gift to myself, I ordered this--a 'used' model of the new 20w Studio Classic JCM 800 combo that has the ability to switch down to the lower 5 watt setting. All that I have read about these amps is that it is a great sounding amp so I look forward to it`s arrival next week. Hope you are enjoying your Marshall 4010 Don--they have great classic Marshall tones all day long! View attachment 12741

I'm really interested in this amp. It was high up on my list of amps when I bought mine last week! I can't wait to hear what you think of it- how it's similar and different.
 
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Don

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I replaced the preamp tubes and electrolytics and the amp sounds good- nice and quiet with no funny noises.

Unfortunately, the power tubes are not even a close match- there's a 24mA difference between them. When one is at 68% max plate dissipation, the other is at 41%. The difference stays with the tubes if I swap sockets.
 
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DutchRay

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Mar 15, 2015
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My buddy had one in white tolex, I never figured out why he sold it (and why not sell it to me?) It was such a great amp for small to medium size stages, everything you want from a jcm800 at reasonable volumes!
 

K_L

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Sep 11, 2014
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I replaced the preamp tubes and electrolytics and the amp sounds good- nice and quiet with no funny noises.

Unfortunately, the power tubes are not even a close match- there's a 24mA difference between them. When one is at 68% max plate dissipation, the other is at 41%. The difference stays with the tubes if I swap sockets.
That is really great you can work on your amp`s circuit! I somehow biased my amp a few years ago, but was very hesitant then & not sure I would ever want to do it again [I guess i`m a 'chicken sh#t!']
 

Don

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A friend who's a hi-fi fanatic gave me a box of 12 lightly used 6550 power tubes to go through! Ten Winged C and two Svetlana. He used four in each of his mono block power amplifiers. He said to take what I need and return the rest when I can. I ran them through his Hickok 600 tester and picked the two strongest and closely matched and put them in the amp and set the bias. The amp sounds great!
 

K_L

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Sep 11, 2014
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A friend who's a hi-fi fanatic gave me a box of 12 lightly used 6550 power tubes to go through! Ten Winged C and two Svetlana. He used four in each of his mono block power amplifiers. He said to take what I need and return the rest when I can. I ran them through his Hickok 600 tester and picked the two strongest and closely matched and put them in the amp and set the bias. The amp sounds great!
Would love to hear it!
 

DrewB

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Unfortunately, the power tubes are not even a close match- there's a 24mA difference between them. When one is at 68% max plate dissipation, the other is at 41%. The difference stays with the tubes if I swap sockets.
Yes, but does it sound great? I very much dislike matched tubes in Marshalls - sterile. If it sounds good, it is good.
 

Don

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Dec 1, 2001
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I can't get over what a great amp this is for all styles of music. I play mostly blues and classic rock, no metal or really hard rock at all and this amp is perfect. I wish I had bought one 40 years ago!
 
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