JCM 900 Advice--NEWBIE

[uraceulose]

Hey all. I am new to the forum and look forward to being a part. I have been listening to marshalls for years and nothing compares. I have a mesa boogie 4x12 and now the time is right for me to get an amp head. I am looking at the JCM 900 hi gain heads. I found two. My question is this:

One Jcm 900 is a 50 watt and one is 100 watt. Does anybody have any suggestions or can someone explain what the difference is?

I play smaller venues with a straight up rock and roll band and the marshall tone is perfect. just a little nervous if 50 watts is going to be enough and i hope it will power the mesa well. any help would be much appreciated.Thanks so much!!!!

 

[wegman]

The difference in volume between a 100 watt amp and 50 watt is only 3db. Hardly a large margin. The 100 watter by design will have more headroom then the 50, meaning the 50 will breakup sooner then 100. Take into consideration each amps tube appetitie and I would go for the 50 watter.

 

[MartyStrat54]

Yes, I too would recommend the 50 watt amp. You will have plenty of power for your cab. I mean any half stack is going to be loud. I personally have gone from the 100 watt amps down to the 50 and 60 watt Marshall's. You can play with more of the power tubes in the mix with a 50 watt amp.

 

[BluesRocker]

+1 on the 50 watt. I own a 4500 duel reverb and it is plenty loud. Plus, as already said it's good to have the power tube drive mixed in with the preamp.

 

[noise5150]

I have a 50 watt DSL and it has tons of great clean range and can get great gain at moderate volume. If you get a 100 watt head get a THD Hotplate to compensate.

 

[Adrian R]

Hey all. I am new to the forum and look forward to being a part. I have been listening to marshalls for years and nothing compares. I have a mesa boogie 4x12 and now the time is right for me to get an amp head. I am looking at the JCM 900 hi gain heads. I found two. My question is this:

One Jcm 900 is a 50 watt and one is 100 watt. Does anybody have any suggestions or can someone explain what the difference is?

I play smaller venues with a straight up rock and roll band and the marshall tone is perfect. just a little nervous if 50 watts is going to be enough and i hope it will power the mesa well. any help would be much appreciated.Thanks so much!!!!

**A 50w Marshall half stack is way loud enough, especially if its got new tubes that are properly biased. One really cool feature of the 900 series is its rear mounted power switch. This switch allows you to 'halve' the power of what the amp is operating at. This way a 100w model (4100/2100) can also run in a 50w mode if required. The 4500/2500 50w models allow you to run the amp in 25w mode if needed. The price difference between the two is marginal, so if I was you I get the 100w model and select the power you need. 100watters, although only slighty louder, do have significantly more head room, and definetely create more noticeable 'grunt' in the 100w mode. This could come in handy if you are doing an outdoor gig with minimal P.A., or jamin' with a really hard hitting, loud drummer with maple drums. A 100w head also drives two 4x12 cabinets better..so if you ever wanted to do the 'full stack' thing you can with ease..and if you've ever experienced jamin' through a fully cranked full stack you would know what I mean as NOTHING can match that kind of audible experience. In fact, the only thing that I can think of to equal that type of audio experience (from an emotional view) would be going to a NHRA contest standing trackside during a top fuel event!

Additionally, even though the 50w models allow you to run in 25w mode, I have yet to see a scenario in where 25w is enough, and the tone suffers quite significantly as well. So for me the 100w model just makes more sense as its never NOT COOL to have more horsepower on tap if needed. Downside of the 100w models is the cost when it comes time to replace the tubes. Twice as much as the 50w model. Lastly, and this is important..DO NOT ATTEMPT TO MOVE THAT POWER SWITCH WHILE THE AMP IS POWERED UP!! You can do serious damage the amp if you do so..Only after the amp has been off for a minute or two can you safely throw the power switch..

Good luck..

 

[5er driver]

DO NOT ATTEMPT TO MOVE THAT POWER SWITCH WHILE THE AMP IS POWERED UP!! You can do serious damage the amp if you do so..Only after the amp has been off for a minute or two can you safely throw the power switch.

Strange that the JCM 900 handbook doesn't mention that. I've thrown the switch while on standby a few times and maybe once or twice while I was playing, I'm not saying it's healthy for the amp to do that.

 

[stone temple pinot]

I would do the 50W, so I could knock it down to 25W.

I have the 100W JCM900 HGDR running into a 1960AC cab. It is stupid loud. It will rattle the windows with vol. on 4.

You could play in a stadium with a 100W half stack.

 

[slowhand]

Your Boogie cab have Vintage 30's?

Speaker sensitivity is another issue at play. The volume of an amp is not completely determined by its output power – speaker efficiency, or ‘sensitivity’ is at least as important. A 3dB increase is equivalent to doubling the amp’s power in terms of the volume you get out. It may sound strange, but a 50W amp with a 100dB speaker is as loud as a 100W amp with only a 97dB one. You can go for maximum volume, or earlier overdrive, depending on how you choose your speakers.

 

[Adrian R]

Strange that the JCM 900 handbook doesn't mention that. I've thrown the switch while on standby a few times and maybe once or twice while I was playing, I'm not saying it's healthy for the amp to do that.

**You know that minimal handbook doesn't say allot ot things! I've seen a few 900s blown up because of that swtich..in addition, I know of a good tech who absolutely HATES that switch, and has fixed many amps due to the improper use of that switch. There is a ton of current flowing through that switch, and throwing it while its powered up can be quite and 'old sparky'. Lastly, as with many things in life, prudence is the wise course of action within this scenario, and powering down the amp to turn the switch takes zero effort and with the benefit of this zero effort keeps your amp healthy and your wallet full.

 

[wegman]

I look at this from a tube replacement standpoint. It is cheaper to replace two power tubes then 4, especially if you are running vintage or NOS tubes. And again as mentioned the difference between 50 watts and 100 is really not that grand volume wise.

It is my opinion that the venues most of us play are to small for a 100 watt amp. 50 is more then sufficient and even that can be overkill in a lot of clubs. I have always been able to control my volume but it became tiresome everytime I rolled my 100 watt Marshall in being told in no uncertain terms to keep the volume down.

 

[Adrian R]

I look at this from a tube replacement standpoint. It is cheaper to replace two power tubes then 4, especially if you are running vintage or NOS tubes. And again as mentioned the difference between 50 watts and 100 is really not that grand volume wise.

It is my opinion that the venues most of us play are to small for a 100 watt amp. 50 is more then sufficient and even that can be overkill in a lot of clubs. I have always been able to control my volume but it became tiresome everytime I rolled my 100 watt Marshall in being told in no uncertain terms to keep the volume down.

I must retiterate! 900 41/2100s have a power switch that allows the amp to run at 50 flippin' watts man! This is such a kick ARSE feature..you've got the extra juice if required..and lets face it..how often do you really change out power tubes man..I mean really...?? And if you do change out tubes often..their really not that much money(CP tubes).. Both models can be acquired for the same dough..and a 100w amp has its obvious advantages..a no brainer in my world..

I think the point is quite simple..'getting a 900? Good, get the 100w for the SAME PRICE and run it in the 50w mode.' This is usually adquate for the majority of the places you will play...BUT if you need it..YOU GOT IT!

Great feature..great feature indeed.. A cranked 100watter through two 4x12 cabs is guitar heaven!!

 

[wegman]

I must retiterate! 900 41/2100s have a power switch that allows the amp to run at 50 flippin' watts man! This is such a kick ARSE feature..you've got the extra juice if required..and lets face it..how often do you really change out power tubes man..I mean really...?? And if you do change out tubes often..their really not that much money(CP tubes).. Both models can be acquired for the same dough..and a 100w amp has its obvious advantages..a no brainer in my world..

I think the point is quite simple..'getting a 900? Good, get the 100w for the SAME PRICE and run it in the 50w mode.' This is usually adquate for the majority of the places you will play...BUT if you need it..YOU GOT IT!

Great feature..great feature indeed.. A cranked 100watter through two 4x12 cabs is guitar heaven!!

Sorry man I missed that. Your right then, that is definetly the way to go.

 

[TheShadowNinja]

Lastly, and this is important..DO NOT ATTEMPT TO MOVE THAT POWER SWITCH WHILE THE AMP IS POWERED UP!! You can do serious damage the amp if you do so..Only after the amp has been off for a minute or two can you safely throw the power switch..

Good luck..

Do you reckon this is the same issue on the tsl100 100w to 25w mode switch?

 

[Adrian R]

Sorry man I missed that. Your right then, that is definetly the way to go.

**Hey Dude..

No need to apologize for the crap I uttered under the influence of several Guiness stouts....especially in light of the pack sweeping them loser bears! God do the bears SUCK this year..I fu&^%$# hate em'! Its time for Lovie and the rest of them bums to take crap show somewhere else!!!!!!!!!!!!!

**Oh and btw..you are right...Gibsons and Marshalls DO RULE..everything else drools........

 

[00jett]

When i had my 100 watt jcm 900 combo i found the half power switch really changed the tone of the amp, and in my opinion not for the better. It was a nice feature but made the amp sound loose especially in the low end. im using a 50 watt dsl and it sounds tighter than the low power mode of my old jcm 900. When running in 100 watt mode it was a beast that i loved tho.

 

[Claret Badger]

Go for the 50w

I have a 4502 DR 50watt - and it is plenty loud to drown out my drummer and leave my ears buzzing

100w is loud - I mean LOUD - but so is 50w

A word about the "switch" - it is cool and darn handy in a bedroom situation granted, to drop down to 25w/half BUT what you are doing is going from PENTODE mode to TRIODE mode on the power valves and you lose some balls/kahunanas/bollocks - and the sound just is not the same:

So I normally keep it in 50w/full fat even when at home

Never mind the width - feel the quality!

hth

 

[LesPaulopolis]

+1 on the pentode vs. triode. Triode sounds darker and more lo-fi.

If you really want to knock a 100w amp down to 50 watts, take two power tubes out and half the impedance on the head (I know, I'm a broken record).

50w is prob. your best bet.

 

[wegman]

**Hey Dude..

No need to apologize for the crap I uttered under the influence of several Guiness stouts....especially in light of the pack sweeping them loser bears! God do the bears SUCK this year..I fu&^%$# hate em'! Its time for Lovie and the rest of them bums to take crap show somewhere else!!!!!!!!!!!!!

**Oh and btw..you are right...Gibsons and Marshalls DO RULE..everything else drools........

Hey dude I am originally a South sider as I am from Berwyn. So believe me with the Bears I feel your pain. Though I now reside in Packer country I still have a soft spot for the Bears. I really thought this was going to be the year to.

If you got chance there is great band in your area called Wicked Soul. I was in the band for a short stint. If you get a chance check them out they are really good.

Anyway to get OT I didn't catch that that amp could switch between 50 and 100 hundred watts when I made my recommendation. That is a pretty cool feature as long as the tone doesn't suffer.

 

[Dickie Fredericks]

+1 on the pentode vs. triode. Triode sounds darker and more lo-fi.

If you really want to knock a 100w amp down to 50 watts, take two power tubes out and half the impedance on the head (I know, I'm a broken record).

50w is prob. your best bet.

Exactly...

Buy the 100 andpull the two outside power tubes. Done.