JCM900 Combo 2x12 100w: sell or upgrade?

[Emopunk]

Re: JCM900 Combo 2x12 100w: sell or upgrade?

As far as tubes go, the preamp tubes on these don't change the sound quite as much as with a lot of other amps, but you will hear a difference. All I've tried in my 50w 900 head were the stock Marshall labeled pre's and Sovtek 5881s that came in it, and a set of Tung-Sol 12AX7 gold pins and a set of Tung-Sol 5881s. The change really helped it out

So I understand that you changed both pre and final valves with Tung-Sol models? Did you need to make adjustments to the circuitry or is it a simple swap? What kind of improvement did you notice?

[Emopunk]

Re: JCM900 Combo 2x12 100w: sell or upgrade?

Ehm.. I know it may sound stupid question to some of you but.. Do I need 8Ω or 16Ω Vintage 30 speaker for my 100w 4102 combo?

[dystrust]

Re: JCM900 Combo 2x12 100w: sell or upgrade?

So I understand that you changed both pre and final valves with Tung-Sol models? Did you need to make adjustments to the circuitry or is it a simple swap? What kind of improvement did you notice?

You can technically change both preamp and poweramp tubes yourself, but you should have it rebiased by a tech after changing power tubes.

Ehm.. I know it may sound stupid question to some of you but.. Do I need 8Ω or 16Ω Vintage 30 speaker for my 100w 4102 combo?

According to the JCM900 owner's manual I found here, the combos have output transformers with 8 and 4 ohm taps. Your combo is a 2x12, and a pair of 16ohm speakers in parallel would yield 8 ohms, so you'd need a 16 ohm Vintage 30.

[Chickenwings]

Re: JCM900 Combo 2x12 100w: sell or upgrade?

Keep it. It is a good amp and also one of the last marshalls to come out of england. A head and 2x12 is just as much of a PITA to carry as a 2x12 combo. Just get a folding trolley.
A fresh set of tubes is always good for re-energizing your amp, but a speaker swap would be cool too. Chuck in a set of jjs in the power section for bottomn end and EH in the preamp slots for low noise/high gain and a gutsy and aggressive midrange. I used a 900 100w head for many years and also owned a 900MKIII master volume 100w combo. This tube combo was great for both, but really...you could put any fresh set of tubes in there, bias them up properly and have a great rocking sound.
I'm guessing you have a pair of g12T75s in there at the moment. They are quite mid scoopy and heavy on the bass and high trebles. They are ok but far from my favourite voice in the celestion range. Very 80s hair metal sounding.
I would recommend a pair of creamback g12m speakers. They will give you that classic midrangey 60s era tone and the other advantage is that they are not very efficient, which means you can run your amp a bit louder on the volume control than you normally would with the speakers you have in there. A pair of creambacks g12ms will be able to handle the 100watts of your amp no problems. They will give a warmer, woodier more vintage vibe to your amp. Nice. The tonality that springs to mind is Eric Claptons "cream" era tone. Nice singing midrange. Your amp, with its two channels and maybe a nice fuzzface and you will be rocking with the best of them.
The other speaker worth looking at is the creamback g12H. These are also fine as a pair with your 100w amp. They have a much stronger low end and a much more present top end than the g12m, much more defined over all. However, they are also a lot louder, so in a club you will not be able to push your amp as hard without upsetting the punters, the soundguy/your bandmates. The tone of these guys is wide open...think along the lines more of Jimi Hendrix "band of gypsies". Big, bold, open and loud.
The last one to look at is a bit unusual for marshall amps but a really good sounding option is to go for a pair of speakers from eminence. Either get a pair of texas heats to soak up your 100watts without breaking a sweat and giving you a really thick tone with no flab. These guys are great for taming the output of big amps and smoothing off the tops. Ive been running a texas heat with a marshall for a while and its just great. Muscular sounding across all the frequency spectrum and never harsh or buzzy. If not a pair of those, then go for one texas heat and one private jack. The private jack is voiced something like the g12m celestion so youll get a groovy, complex tone by running the texas on one side and the private jack on the other...bear in mind tho that the private jack is only rated for 50 watts. This is fine as you are running it in a pair with another speaker, so even a pair of 50 watt speakers will be ok with your 100 watt amp, but it will be working closer to its limits so you will get some of that famous "cone cry" of the 60s. However, one speaker running like that, sitting next to the 150watt texas heat and youll get the best of both worlds. One will be loose and spongy (and just plain cool) and the other will be powering out the low end like it doesnt care. It is a sound ive used in the studio and run mics on both speakers to get a really great stereo spread. Sound engineers love it. For live...just mic the texas.
Ok...so that's 4 speaker options that are all nicer than what you have there:
1. 2 x creamback g12ms
2. 2 x creamback g12hs
3. 2 x texas heats
4. 1 x texas heat 1x private jack
Hope this info is useful
Keep your amp, its cool ....maybe a bit of armor all on the tolex and possibly some shoe nugget and your amp will be looking great too and you will remember why you liked the amp in the first place.

[allbutromeo]

Re: JCM900 Combo 2x12 100w: sell or upgrade?

I'll never get why 900s seem to be so hated, it's nice to see other people who like them as much as I do. I like V30's with these amps because they have a more pronounced mid range compared to t75s, and since channel b has a different voicing hard wired into it that scoops the mids the speakers help balance it out a little. I run mine through a v30 and M65 creamback sounds great. As for my choice in tubes, I mainly went with Tung-Sol because I've had good experiences with them, and unlike I've read in online reviews of their 12ax7s, I've never had one go bad prematurely in almost 10 years of using them. Also I read a few comparisons online and nearly all of them rated their 5881s as one of the best modern production 5881s on the market, closest to vintage sounding. Overall the effect they had on the amp was more chime/sparkle on channel A but without getting shrill or "ice picky" and they smoothed out some of the fizziness on channel B and get nice and fat with smooth breakup at higher volume.
Ps yes I did re-bias it after changing power tubes. I don't remember the exact numbers, but it came out about 73% dissipation

[Emopunk]

Re: JCM900 Combo 2x12 100w: sell or upgrade?

You guys are incredible.. I came with doubts, now I know I will keep my old Amp and just pimp it up a bit
@gibson175, I see you didn't suggest at all the Vintage 30. So you think the option of one vintage with one of the 75 I have wouldn't be good?
@allbutromeo, I pretty much find it already to have a good sound, but one thing I would love to improve is the fizzines on the b-channel. Do you say it would be enough to change the pre section (is it correct?)?

Now for anothe small problem I have. I used to have a lovely cat. She's now dead unfortunately, but at the time she tried couple of time to refine her nails in my amp
So in the end my 4102 has two tears in the tolex. I would like to repair it if possible. Should I post pictures to see if you can explain to me how to do?

Thank you and lots of regards from Italy!!

[Boogie Bill]

Re: JCM900 Combo 2x12 100w: sell or upgrade?

I think I would probably keep the amp, and rather than replacing speakers I'd try to find a matching closed-back Marshall 212 extension cab to use with it.

Or get a JCM 900 head and cab--these can be had very reasonably, and a backup amp is always a good thing.

Now that doesn't solve the weight problem. You might want to look into getting a smaller combo, say 18-35 watts for when you play smaller rooms. A "pick up and go" amp. Perhaps a used Marshall DSL40 that would have a tone similar to the JCM, or go for something like a Mesa, Fender, or Peavey Classic...an amp that could back up you JCM, handle smaller venues, and expand your tonal options...should you get a gig with a jazz quartet or a country-rock band in the future.

There are lots of possibilities for you. If you really love the tone of your amp, the making some minor upgrades and tweaks is a good idea. Having a backup rig is a necessity--and hopefully, it's close enough to your Number One that it won't stress you out if you have to gig with it. And having an amp that is tonally different, and has a different power level for other venues...well, that can be very handy too.

Tough choices. Good luck; let us know what you decide.

Bill

[Emopunk]

Re: JCM900 Combo 2x12 100w: sell or upgrade?

I think I would probably keep the amp, and rather than replacing speakers I'd try to find a matching closed-back Marshall 212 extension cab to use with it.

Or get a JCM 900 head and cab--these can be had very reasonably, and a backup amp is always a good thing.

Now that doesn't solve the weight problem. You might want to look into getting a smaller combo, say 18-35 watts for when you play smaller rooms. A "pick up and go" amp. Perhaps a used Marshall DSL40 that would have a tone similar to the JCM, or go for something like a Mesa, Fender, or Peavey Classic...an amp that could back up you JCM, handle smaller venues, and expand your tonal options...should you get a gig with a jazz quartet or a country-rock band in the future.

There are lots of possibilities for you. If you really love the tone of your amp, the making some minor upgrades and tweaks is a good idea. Having a backup rig is a necessity--and hopefully, it's close enough to your Number One that it won't stress you out if you have to gig with it. And having an amp that is tonally different, and has a different power level for other venues...well, that can be very handy too.

Tough choices. Good luck; let us know what you decide.

Bill

I actually have a smaller back-up, I have a Fender Mustang III v2, which is really good for my tastes. Quite portable too [emoji2]

[Chickenwings]

Re: JCM900 Combo 2x12 100w: sell or upgrade?

@gibson175, I see you didn't suggest at all the Vintage 30. So you think the option of one vintage with one of the 75 I have wouldn't be good?

yeah that's a popular combo for hard rock/metal. I didn't mention the v30 because it is such a strident and cutting speaker. The ones i recommended are not as efficient and not as present as the v30 so you will be able to have a warmer, fatter tone at the same volume. Really efficient and cutting speakers are fine, but it is very rare that people who have 100 watt amps need more volume. Generally, it is more useful to tame your big powerful amp so you can get a good tone at a useable stage volume, one that is thick and meaty, but not too loud for 1. The people in the front row 2. The sound engineer - who invariably want you to turn it down no matter what volume you play at and 3. the rest of the band especially the vocalist. By choosing not to have the loudest, most efficient speaker, you can use more of your amp. The other thing to steer clear from especially with 900s is speakers that are geared towards the treble end of the spectrum. Have a think about how you usually set your tone controls....if you want to sound big and bold rather than "swarm of bees" then speakers that do not have a pronounced treble will be a good fit for that amp. The other thing about 900s and especially the 100 watters is that they tend to sound better when the power tubes are actually working rather than sitting down on 1,2 or 3. Loud speakers mean you can never get your power tubes working in the "tone zone" in most clubs. The only time really you can open your amp up is at an outdoor stadium, but even then what is the point of being so loud that you can't hear the rest of the band?
It is also worth considering that speakers that sound good in closed back cabs, often sound less than stellar in open back cabs, and seeing as you have a combo its worth looking for speakers that will suit.
Anyways...my 2c worth.

[Emopunk]

Re: JCM900 Combo 2x12 100w: sell or upgrade?

@gibson175 what you say is so true about volume! I really have troubles to push my amp in most of the usual settings. Your suggested speakers perform well in a combo, for what you know?

[dystrust]

Re: JCM900 Combo 2x12 100w: sell or upgrade?

@allbutromeo, I pretty much find it already to have a good sound, but one thing I would love to improve is the fizzines on the b-channel. Do you say it would be enough to change the pre section (is it correct?)?

With most master volume amps the majority of the tone comes from the preamp section. That's certainly the case with my Marshall Jubilee which isn't hugely different from your JCM900. IMO finding the right preamp tube will dramatically help but may not entirely cure the fizziness you're referring to. To completely fix the issue you'll probably want to swap preamp tubes and at least one speaker, and possibly power amp tubes as well.

[Rand-O-Monium]

Re: JCM900 Combo 2x12 100w: sell or upgrade?

Looking forward to the progress report!


& + another for keeping it,just get some casters or a dolly board or something...

[Emopunk]

Re: JCM900 Combo 2x12 100w: sell or upgrade?

Thank you, I am making contacts with a shop to buy one or two Creambacks
Then I'll see how it works and decide when to refresh the tubes section.

In the meanwhile I need to repair a couple of tears in the tolex. If you have any favourite technique please share!
I found this:

https://www.youtube.com/watch?v=l4B4eZb0lI0

Is it an accettable way to do it?