My JCM900 should arrive today!!

[SepultuRick]

Re: My JCM900 should arrive today!!

It's 3 12ax7 tubes and for el-34's I heard JJs, Svetlana, and Sovteks are good. The 12ax7's are pre-amp tubes, these you can install on your own. The power tubes need to be brought to amp tech to bias and install. Biasing just means setting the current going through the tubes, this part requires you go inside the amp where the wiring is and is really dangerous to play around. Also check the vault section a pre-amp tubes for high gain are recommended there.

I have the 50 watt combo which i think uses jus tthe 2 el34 tubes

[greendy123]

Re: My JCM900 should arrive today!!

so i need 2 el34 valves and 2 12AX7 valves and 1 12X7 valve. correct???

can i use any brand? can i fit them myself or so i need to take them in to a professional?

It's 3 12ax7 tubes and for el-34's I heard JJs, Svetlana, and Sovteks are good. The 12ax7's are pre-amp tubes, these you can install on your own. The power tubes need to be brought to amp tech to bias and install. Biasing just means setting the current going through the tubes, this part requires you go inside the amp where the wiring is and is really dangerous to play around. Also check the vault section a pre-amp tubes for high gain are recommended there.

[SepultuRick]

Re: My JCM900 should arrive today!!

so i need 2 el34 valves and 2 12AX7 valves and 1 12X7 valve. correct???

can i use any brand? can i fit them myself or so i need to take them in to a professional?

[Buckeyedog]

Re: My JCM900 should arrive today!!

Gain and Tone. V1 is the most important tube in your chain. that's the first small tube, farthest from the power tubes. That one has the most impact on overall tone and gain. The new Tung Sol has plenty of nice tight gain and sounds really good. Chinese and EH's also have nice tight crunch. Sovtek LPS is nice as well. If you put crappy tubes in your amp, it will not sound very good. Period. Don't run it through crappy speakers either.

[SepultuRick]

Re: My JCM900 should arrive today!!

ok so what tubes should i buy and why? i know some have been suggested already but why? I play mostly metal if that helps

[ErikH]

Re: My JCM900 should arrive today!!

Don't worry bro, take it one step at a time. In the end you'll have tone to die for. Get the amp taken care of so you can at least play through it. Who knows, the pickups you have now may sound better or be what you want afterwards. With the Gain Sensitivity and Preamp Volume on full, you probably don't need an overdrive right way. Doesn't hurt though.

[Buckeyedog]

Re: My JCM900 should arrive today!!

Yes......isn't it great?!! Spend $$ only to spend more $$. Welcome to being a gearhead!

[SepultuRick]

Re: My JCM900 should arrive today!!

great so i need new pickups, new tubes, amp serviced, guitar set up properly for new string gauge and err oh yeah maybe a new overdrive pedal if i need to push my amp at all!!!!!!!

[ErikH]

Re: My JCM900 should arrive today!!

I just found out off the guy i bought my jcm900 amp from that the tubes are the originals that were in it from 1992!!!!!!!! this means they need changing right?

Oh yeah. Preamp tubes last longer than power amp tubes but to get it to really sound the way it should, new tubes throughout will be worth it. It's like changing the oil in a used car you get from someone. You'll know what's in it and how long it's been since the last change.

[Buckeyedog]

Re: My JCM900 should arrive today!!

Absolutely they need to be replaced. SED's and JJ's are very nice power tubes. Good pre's for Marshall's are the new Tung Sol reissue, Chinese, EH's. E-mail or call dougstubes.com or revolutionguitar.com. Both great guys to deal with and will help with selection.

[SepultuRick]

Re: My JCM900 should arrive today!!

I just found out off the guy i bought my jcm900 amp from that the tubes are the originals that were in it from 1992!!!!!!!! this means they need changing right?

[ErikH]

Re: My JCM900 should arrive today!!

To answer the questions not answered on my page (cause half are..lol).

Set the impedence to whatever the speaker is rated at. It can be set to 4(16) or 8. The 4(16) setting is for either 4 ohm or 16 ohm loads.

Hmm, the others have been answered already. If we don't see ya for a few days we'll know why...LOL LOL.

[greendy123]

Re: My JCM900 should arrive today!!

Check erikh profile, it has a link to stuff about the amp. For the question the pots I would just get it checked out by tech to get it cleaned up and possible find any problems now before they get worse.

[ShredFetus]

Re: My JCM900 should arrive today!!

Standby switch: When you turn the amp on, switch the POWER switch on FIRST while the STANDBY switch is OFF. Then after a few mins turn the STANDBY switch ON. Complete the procedure in reverse when turning it off. ie. Standby off for a few mins, then power off.

[SepultuRick]

Re: My JCM900 should arrive today!!

ok it came!!, its second hand off ebay. It seems in good condition but the volume knobs crackle quite a bit when i move them. Can this be fixed?

the high or low output option on the rear of the amp is for changing the wattage i presume. The low output option more suitable for lower volumes? is this right?

also the impedence can be changed between 4 or 8 ohms. which should i have it on?

i am also unsure what the standby switch is about and also the 2 channel thing is confusing me a bit. Is the gain sensitivity knob just an extension of the preamp volume??

thanks for the help guys.