Marshall JCM 800 Owners

wntbtw

wntbtw

New member
Hi--I need you advice please! I just purchased a used 1982 JCM 800 amp and need to change all of the tubes and would like your opinion on which ones i should install. I would like to get as close as possible to whatever the 'stock' tubes were for these amps, but also know that I want more of a slightly 'bright' sound/tone as opposed to a 'dark' sound/tone [but not totally 'bright'--just 'mid-bright!] And i`m leaning towards the '6550' power tubes unless everyone tells me that the EL34`s give a 'brighter' tone. Please tell me what tubes and manufacturer you think i should use [ie Sovtek, EH, etc] Thank you for any help you can offer.
 
Re: Marshall JCM 800 Owners

Both of my JCM800's still have the stock 6550 tubes...but EL34's are the classic Marshall tone. You'll have to have one resistor in your bias circuit changed to expand the range of adjustment if you want to switch to EL34's. I will probably do that to mine sooner or later.

My brother Bruce tells me he likes new Svetlana EL34's and I like those and also Sovteks. I don't use any new 12ax7's...only NOS GE's, Telefunken or RCA's, though the Russian made Sovteks can be nice. I don't use Chinese 12ax7's if I can help it...but it's been a while since I've tried any. In the past, I thought they tended to be microphonic and to bright sounding but that may have changed.
 
Re: Marshall JCM 800 Owners

The 6550 used by Marshall during that period was supposed to be the GE 6550. If your looking to make it "period correct", then be careful to get a bright & clean current production 6550. Parhaps Winged C. Many of the modern 6550's don't always get the brightness and high head room of the original GE 6550. Actually, a current production KT88 might give a sound closer to a NOS GE 6550, than a current production 6550.

There was a Tung-Sol 6550 back in the late 60's that is supposed to sound quite different from the regular GE 6550. I don't know because I've never heard one, and it was not used by Marshall into the 80's.

I kinda wonder what a 6CA7 would do in this type of application? The 6CA7 is in between the EL34 and the 6550 types. That might be an interesting option?
 
Re: Marshall JCM 800 Owners

I'm not a fan of EL-34s in single channel JCM800s. To my ears they can be rather shrill and lacking in the lows. Very different than how they seem to sound in JMPs. I've often wondered if Marshall changed the JCM800 tone stack to sound 'right' with 6550s.

Dual channel 800s are another story. That circuit is not the least bit lacking in bass / low mids, so I prefer EL-34s in these amps for their extra brightness, cut, and aggression. I don't own an 800 at the moment, so I'm GAS'ing for both an early 2203 w/ 6550s and a 2205 with EL-34s. In fact I know of a great sounding 2205 locally, just need to see if I can get them to come down to a realistic price.
 
Re: Marshall JCM 800 Owners

wntbtw said:
Hi--I need you advice please! I just purchased a used 1982 JCM 800 amp and need to change all of the tubes and would like your opinion on which ones i should install. I would like to get as close as possible to whatever the 'stock' tubes were for these amps, but also know that I want more of a slightly 'bright' sound/tone as opposed to a 'dark' sound/tone [but not totally 'bright'--just 'mid-bright!] And i`m leaning towards the '6550' power tubes unless everyone tells me that the EL34`s give a 'brighter' tone. Please tell me what tubes and manufacturer you think i should use [ie Sovtek, EH, etc] Thank you for any help you can offer.
Click to expand...

My Sovtek 6L6s sound beautiful, so I can say Sovtek is a pretty good brand. Not the best, but definitely a good value. I'd say go for 6550s for the extra bawls. Sovtek, JJ, EHX or Tung-Sol would be the brands I'd recommend.
 
Re: Marshall JCM 800 Owners

dystrust said:
I'm not a fan of EL-34s in single channel JCM800s. To my ears they can be rather shrill and lacking in the lows. Very different than how they seem to sound in JMPs. I've often wondered if Marshall changed the JCM800 tone stack to sound 'right' with 6550s.

Dual channel 800s are another story. That circuit is not the least bit lacking in bass / low mids, so I prefer EL-34s in these amps for their extra brightness, cut, and aggression. I don't own an 800 at the moment, so I'm GAS'ing for both an early 2203 w/ 6550s and a 2205 with EL-34s. In fact I know of a great sounding 2205 locally, just need to see if I can get them to come down to a realistic price.
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There's no lack of bass in any of the single channel JCM-800's I've owned. Maybe if you turn the master down to "1" and crank the preamp to "10"...but no professional would use one like that! :smack: I'm a huge fan of that amp and have owned four of the 50 watters...plus one of the dual channel 100 watt heads. Didn't like the dual channel version nearly as much as the 50 watt single channel amps. A lot of JCM-800's came with G12M-70 speakers which are probably Celestion's least popular design. Changing to a better speaker makes all the difference in the world. I've come to love the G12-65 speaker in my JCM-800 4010, and I'm looking for a set to put in my 2 x 12 JCM-800 4104 single channel 50 watt. I changed the 6550's to EL-34's in my previous 4104 and it sounded incredible with no lack of bass with one Classic 80 and one G12-65. Should have never sold that amp but I've since replaced it with an identical one...although I haven't yet changed the tubes to EL-34's. Lew
 
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Re: Marshall JCM 800 Owners

A primary consideration on using 6550's or EL34's in Marshalls, is how much you use power tube distortion. If you never use much power tube distortion and prefer to shape your tone with effects and/or in the pre-amp, then using 6550's may be a better way. If you want more of that classic power tube distortion at a somewhat lower volume level, then EL34's are the way to go. Both types of tubes are a capable of being bright or dark.
 
Re: Marshall JCM 800 Owners

Lake Placid Blues said:
A primary consideration on using 6550's or EL34's in Marshalls, is how much you use power tube distortion. If you never use much power tube distortion and prefer to shape your tone with effects and/or in the pre-amp, then using 6550's may be a better way. If you want more of that classic power tube distortion at a somewhat lower volume level, then EL34's are the way to go. Both types of tubes are a capable of being bright or dark.
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Thanks to everyone for their input--it`s been great reading all of them! I do need to re-tube my single-channel JCM 800 Combo, but need to mention the fact that I`ll be playing it at lower/bedroom volumes instead of 'cranking' it so am I to install the EL34`s as 'Lake Placid Blues' recommends? I really don`t know the difference in sound/tone between a 'power tube distortion' or a 'pre-amp distortion' and what amp settings is needed to achieve either one. I don`t know anything concerning this and therefore need to learn everything! I just would like to have a true JCM 800 sound/tone at a lower volume!! Please don`t tell me to get another amp as i have my heart set on this one and i`ll use a OD pedal if necessary [which i also know not too much about!] I`m just trying to achieve a great Marshall sound at unfortunately a lower volume--ugh!--so any and all help will be greatly appreciated by me!
 
Re: Marshall JCM 800 Owners

Hi! I forgot to mention that my amp [JCM 800 Combo] has one 12" Celestion 'Vintage 30' speaker.
 
Re: Marshall JCM 800 Owners

Well Marshalls are very loud amps. The loudness you will need, even with EL34's, before power tube distortion becomes a factor, is way beyond bedroom levels. The Vintage 30 is also a rather loud speaker.

To use the amp at bedroom levels, you will have to create distortion (if you use it) using some kind of effects pedal or something. In that case it won't really matter if you use 6550's or EL34's.

I'd probably completely re-tube it, but the bias has got be set up right on Marshalls to get the best out of them. Ofton a bad sounding Marshall is the result of poor quality and/or worn out tubes, and incorrect bias adjustment. Take it to a good tech and have the bias checked. When the amp is re-tubed make sure that the bias is corrected for the new tubes, what ever you decide they be. I tend to prefer JCM 800 era Marshalls with EL34's myself, but that is a just my personal prefrence. The 6550 also has merits in your case, and if the amp's bias circut is already set up for 6550's, then it may not be worth the hassle to change tube types.
 
Re: Marshall JCM 800 Owners

wntbtw said:
....... I really don`t know the difference in sound/tone between a 'power tube distortion' or a 'pre-amp distortion' and what amp settings is needed to achieve either one......
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Power tube distortion is the classic type of distortion of blues and classic rock ..ect...The amp has to be run very loud to obtain it. A lot of guys like power amp distortion, or "overdrive", because it's more touch sensitive and in many ways more dynamic. Some people find it more musical sounding too.

Pre-amp distortion is what most modern high gain amps depend on. I find that people ofton use the term "gain" to decribe the amount of it. It's a buzzier type of distortion, but a lot of it can be obtained at just about any volume.

I find that sometimes a little of both is the best way to go.
 
Re: Marshall JCM 800 Owners

I have a 1982 JCM 800 2204 and I'm using New Sensor tubes in it, thier "Mullard" EL34s and "Tung-Sol" 12AX7s. So far this is the best combination of tubes I've used in this amp, I'm really happy with them.

Cheers,

CJ
 
Re: Marshall JCM 800 Owners

My 2 cents:

An in-between 6550 & EL34 is the JJE34L. I think you're probably better off experimenting with pre-amp tubes in V1 though. My experiences with this lead me through a ton of 12AX7's/Ecc83's and I finally ended up using NOS RFT's. If you're on a tighter budget, the best sounding new production pre's I found were Tung-Sol re-issues.
 
Re: Marshall JCM 800 Owners

I like Tung-sol 12AX7s and EH 6CA7s for power tubes. To me the 6CA7 is a nice middle ground between EL34s and 6550s and are still biased like EL34s.
 
Re: Marshall JCM 800 Owners

Groove Tubes matches their tubes based around when in the power range they start to distort, so a pair/quad of EL34 tubes rated at 2 or 3 from them will all distort at the same time, and very low in the volume range.(good for bedroom...not so good for stage)
Sure, they get (GT) slammed, but if they re-lable Sovteks, what's the difference in buying Sovteks at the store, but for the matching GT does?

JJ tubes are all the rage right now, but they're cheap Eastern-Bloc crap just like Sovtek or the tubes from Ei in Yugoslavia. I had a JJ EL84 die on me after only 6 hours, so they're not the wonder tube of the ages, just a fairly well made tube for today's standards.

Overall, I agree with Lew, that you should look into finding some quality NOS USA or British tubes and let that amp realize how good it can be.
 
Re: Marshall JCM 800 Owners

Lewguitar said:
There's no lack of bass in any of the single channel JCM-800's I've owned. Maybe if you turn the master down to "1" and crank the preamp to "10"...but no professional would use one like that! :smack:
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My comments are the result of experience with two EL-34 equipped single channel 800s. The first was a 2204 from '87 that Dave Rogers lent to me over a weekend while I was doing rhythm guitar overdubs on a heavy rock recording. I had the gain up rather high (8-10) and the master up just quiet enough to not rattle my furniture (around 4). Not a bad sound, but not as good as 6550s. I'm sure I like a much dirtier sound than you do, and that may influence my preference.

Regarding the JMP comment, about a year ago I A/B'd my brother's 1978 JMP 2203 against a 1981 JCM800 2203 both with EL-34s. The JMP was much more full sounding, whereas the JCM seemed scooped and the brightness was difficult to control. No amount of tweaking could make the JCM sound like the JMP.
 
Re: Marshall JCM 800 Owners

both you guys are probably right based on what tubes were in those amps.

could have been the preamp tubes and output tube selection. I bet if you retubed the 2203 and 2204 with deeper bass response tubes like JJ EL-34Ls and high quality tone picked pres you'd get more bass response.
 
Re: Marshall JCM 800 Owners

Lewguitar said:
I've come to love the G12-65 speaker in my JCM-800 4010, and I'm looking for a set to put in my 2 x 12 JCM-800 4104 single channel 50 watt. Lew
Click to expand...

So you're the other guy!! :-)

After trying em all - I keep coming back to my JCM800 cab with the 65's in em. Would love to try the new Heritage version to see if they sound like the originals.
 
Re: Marshall JCM 800 Owners

i just got a set of the GT Mullard EL34's in mine to go with a GT ecc83 in v1 and two 12ax7's and it sounds sweet as poon
 
Re: Marshall JCM 800 Owners

JCM 800's are my favorite of all the marshall amps. I used to have a 200w major, a JMP , a jcm 900 and a jcm 800. They have plenty of crunch, but don't sound as bright (buzzy) and thin as the 900 series. The older marshalls than the 800's needed to be super loud to get the crunch, so i ended up using pedals.
So, for rock the 800's are great. Still loud tho.
You need a power brake. This will allow you to run the amp at levels it is designed for, but you can turn it down before the load hits the speaker - great tone at low volume!
Re tubes: Try big bottle electro harmonix 6ca7's. These are really just military spec. El34's which will give you lower noise, and fatter bottom end.
 
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