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		UG Community @ Ultimate-Guitar.Com > Instruments > Guitar Gear & Accessories
1981 Marshall JCM800 100w lead head(2303) help..

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11-21-2012, 05:35 AM

#21

gumbilicious

beginner

Join Date: Oct 2007

Location: on the road... again

Quote:

Originally Posted by Blktiger0

I'm taking up where 311 left off on this thread-jacking process:

Cath, what are the differences between using a Pentode/Triode method of half-power

i do know that a triode uses only 3 electrodes (anode, cathode, grid) and a pentode uses 5 electrodes (anode, cathode, more gates).

Quote:

Originally Posted by wikipedia

Triodes have a lower internal anode resistance, and hence higher damping factor when used in audio output circuits, compared with pentodes, when negative feedback is absent. That also reduces the potential voltage amplification obtainable from a triode compared with a pentode of the same transconductance, and usually means a more efficient output stage can be made using pentodes, with a lower power drive signal.

basically a pentode is more efficient in the output section of an amp. switching it to triode mode should be little more than adjusting values to the pins of the tube wherein it loses efficiency and lowers the wattage.

Quote:

Originally Posted by Blktiger0

and using the "turn off two tubes" method? I'm not talking about pulling tubes, I mean as a built-in function. Is there a sound difference, cost difference, etc.?

I'm just curious becuase it bothers me when I run my amp in half-power that I'm wearing the tubes in a uneven fashion.

Stupid OCD...

afaik, this should not really be too much different than pulling tubes... so maybe cath knows something i don't here.

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11-21-2012, 06:02 AM

#22

Blktiger0

The Name's Devon! ;)

Join Date: Sep 2007

Location: Marrietta, Ohio, USA

Quote:

Originally Posted by gumbilicious

i do know that a triode uses only 3 electrodes (anode, cathode, grid) and a pentode uses 5 electrodes (anode, cathode, more gates).

basically a pentode is more efficient in the output section of an amp. switching it to triode mode should be little more than adjusting values to the pins of the tube wherein it loses efficiency and lowers the wattage.

afaik, this should not really be too much different than pulling tubes... so maybe cath knows something i don't here.

I'm aware of the difference between Pentode and Triode, I mostly meant build differences in terms of expense and differences it might have on your tone. Thanks for the info, though.

Yeah, they're basically the same, the amp just "pulls" the tube for you, as I understand.

I'm just curious about whether one would be preferable to the other for certain things

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11-21-2012, 04:26 PM	#23
wiht1 Registered User Join Date: Nov 2012	Thank you fellas, genuinly appreciated.

11-21-2012, 04:32 PM

#24

mmolteratx

UG God

Join Date: Sep 2008

Location: Richardson, Texas

Quote:

Originally Posted by gregs1020

righto gumbi.

2 - 1981 50 watt (2204) heads have sold on the bay recently. one was $1089 and the other $1075.

the 100 watter (2203) may be slightly more or less desirable, i honestly don't know. but that's what heads of the same year went for.

Also keep in mind that eBay prices are a bit higher than what you'd be able to sell for elsewhere, but with fees, you wind up paying ~12% of whatever you get these days, plus an additional 9% on the shipping costs. I'd probably pay $800 for a dead mint one. Maybe a tad more, depending on how badly I wanted it. There are just too many of them on the market to pay any more than that.

Quote:

Originally Posted by Cathbard

The 100W is more desirable. You can turn a 2203 into a 2204 by just pulling two tubes, you can't turn a 2204 into a 2203 without major surgery.
1981 makes it a vertical, that makes it one of the most sought after amps in history. It's the last true Marshall before the bean counters got control of the company and ****ed everything up.

Not really. For us, maybe. But for the majority of the market, the 50w JCMs tend to be more popular. I dunno what it is about 50w but lots of people tend to like that. Maybe because it seems like a nice midpoint between 100w and some dinky little practice amp.

Quote:

Originally Posted by bubb_tubbs

Everything here is true, though it still shouldn't be worth more than about $1100.

I've never paid more than $900 for a JCM 800 in my life, and I've owned 3.

Honestly, $1100 would really be pushing it. That's retail level, and maybe that's worth it to some but only if they get the reassurance of buying from a legit store who will take care of any undetected problems. Private sale is worth $900, absolute maximum, IMO. And that's being a bit generous.

EDIT: Also, keep in mind my prices don't include shipping, which is usually a bear these days. Expect $70-80 for that and just pass on the real cost in addition.

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11-21-2012, 04:42 PM

#25

patriotplayer90

Registered User

Join Date: Jul 2007

Quote:

Originally Posted by gumbilicious

i have seen the 2204 at guitar center for ~1100, so maybe a 2203 may go for 1200 or 1300. that would prob be considered full on retail. if you sell it to a guitar center i wouldn't expect to get more than 500 or 600 bucks for it (maybe less).

if you sell it on CL or ebay you may be able to sell it for around 1000 usd. most savy guitar gear buyers would want it for 800 or less. if you have patience and don't need to get rid of it too quick you may be able to get someone to buy it for like 1200 to 1400.

someone could prob give you better numbers. btw, marshall reissued this amp and it sells for ~2300 bucks O.o

I bought a '81 JCM 800 2204 that was modded for extra gain by Bruce Egnater a few years back for less than a grand at GC. It certainly seems like prices have risen.

11-21-2012, 05:01 PM

#26

mmolteratx

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Join Date: Sep 2008

Location: Richardson, Texas

Quote:

Originally Posted by patriotplayer90

I bought a '81 JCM 800 2204 that was modded for extra gain by Bruce Egnater a few years back for less than a grand at GC. It certainly seems like prices have risen.

10 years ago they were selling for $500. Of course prices have risen a bit. Though a few years ago, Egnater's mods also weren't really worth a whole lot due to a lack of brand recognition.

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11-21-2012, 05:10 PM

#27

patriotplayer90

Registered User

Join Date: Jul 2007

Quote:

Originally Posted by mmolteratx

10 years ago they were selling for $500. Of course prices have risen a bit. Though a few years ago, Egnater's mods also weren't really worth a whole lot due to a lack of brand recognition.

It was two years, tops. I know his production amplifiers had been established by that point, but maybe it wouldn't be worth any more now. If I could go back in time, I would rather pay $500 for an original.

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