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| |-+  JCM 800 2203, 2204, 2550, 2555
| | |-+  Newbie Just ordered the 2555
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Author Topic: Newbie Just ordered the 2555  (Read 8192 times)
Keith
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« on: July 31, 2009, 10:43:57 PM »

Well I finally broke down and bought a 2555. I added a master volume, preamp out, and power amp in. I can't wait to get this thing in and fired up. Any tips from other Ceriatone owners for a first time buyer?
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cmoore
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« Reply #1 on: August 01, 2009, 12:24:46 AM »

What can you say, they are great, affordable, hand wired amps.   If you bought a complete amp, make sure you check the bias after it gets to you.
Good Luck
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Keith
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« Reply #2 on: August 01, 2009, 11:57:52 AM »

How do you check the biasing? Can I do it or should I try to find a amp tech? Or, can a place like (and I hate this place) Guitar Center do it?
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wyatt
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« Reply #3 on: August 01, 2009, 02:47:25 PM »

I wouldn't worry too much about the biasing, I'm sure it's biased before shipped, chances of it drifting enough to affect anything seems slim...but...it's something worth knowing.

The amp is set up with bias check points.  You'll see four red jacks and one black on on the back of the chassis.  With a DMM set to measure voltage (mV), you plug the red probe of the DMM into any of the red jacks and the black probe is grounded through the black jack.  This bias points have a 1 ohm resistor to ground installed.  Thanks to Ohm's Law, you can then read 1mV for each 1mA of cathode current.  So, if you need to bias a tube to 40mA, dial in the bias pot until your DMM reads 40mV.

From there a simple table like this can help you...
http://www.webervst.com/tubes1/calcbias.htm

Note, you need to know the plate voltage.  Normally, we get this on a EL34 amp by measuring voltage from Pin 3 (red probe on pin 3, black probe to ground, like the chassis).  This exposes you to high voltage...400-500VDC in enough Amperes to kill you.  So, if you aren't wanting to go through all the reading and preparation and safety precautions to become an amp tech...just as Nik what they are averaging in his shop...or ask around here.  Changes in wall voltages will affect plate voltages, but that's unavoidable (you can't count on amp techs or clubs to have the same wall voltages as your house anyway).

As for dissipation...I start around 60%, the recommended 70% is often quite hot, and modern tubes are the most robust. 

You'll note you have 4 tubes , 4 bias points and only 1 bias pot.  Well, you have to average everything out so all the tubes are as close to you intended point as possible.  This is were matched sets come in, if a set is truly matched they should all bias up to within a couple of mAs of each other.

2555, eh?  That's a hell of a lot of output, good luck with that Prince Albert Hall gig.  Smiley
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cmoore
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« Reply #4 on: August 01, 2009, 02:55:13 PM »

It is certainly possible to do yourself, but it requires some knowledge and a little bit of test equipment.   If you live near me, I can do it for you.   As far as GC goes, I guess it depends on the store.   Maybe some of them employ an amp tech, I really don't know.
Good Luck
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Keith
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« Reply #5 on: August 01, 2009, 03:05:12 PM »

Thanks a lot guys. I'll plug it in and if it sounds flabby, I'll just take it to a tech. Hopefully this tech will give me some hands on. It doesn't sound like its safe enough for a new guy just to "just go in there". I decided the 100W would be better in the long run. I like to buy things I will keep for a lifetime. I think I read every forum on the internet that mentioned Nik's amps and the only bad things I heard were other amp makers complaining about the price. From what I heard this guy is one of the best. I hope he never changes. Someday i dream of a wall of amps and with his prices and quality I just might get there.
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cmoore
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« Reply #6 on: August 01, 2009, 08:04:56 PM »

Don't let me worry you about the bias stuff.  Like "wyatt" said, Ceriatone must have set the bias when they fired up your amp.  I am sure every thing is fine.    But there is a lot of wiggle room with bias.   After awhile, the numbers become almost meaningless.    Many times I have adjusted bias until the player says "OK I like it right there".  Then I check with a meter.   If the numbers don't seem stupid, to one extreme or the other, then I am done.   Does not matter if it is at 53% or 79%.   It only matters how the amp sounds to your ears and fingers.
We have amps made by Carol Ann, Roccaforte, Fargen, Two Rock, etc. etc.   I always check the bias when it gets to me.   You just never know for sure, unless you look.   And I have found a few problems doing so, but I see a lot of amps.
Enjoy your new, hand wired, Marshall master piece.   That amp will out last all of us!!!!!
Good Luck
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wyatt
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« Reply #7 on: August 02, 2009, 06:29:05 PM »

  Like "wyatt" said,...

No punctuation necessary, Wyatt is my real first name. 
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Keith
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« Reply #8 on: August 07, 2009, 10:29:24 PM »

Mine will be here Monday the 10th. Can't wait to get home from work that day and fire it up. I'm sure I will play it for a while by it's self but I can't wait to get into a stereo mix with it and mt H&K Triamp MKII.
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Keith
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« Reply #9 on: August 16, 2009, 08:04:14 PM »

This thing sounds awesome. I just can't get enough of the sound this thing has. Lots of chunk, not a super high gain, and if you want cleans try something else. The cleans are alright but not good or even great but thats cool because I wasn't wanting that anyway. I wanted good Marshall crunch and this this delivers. Period! Nik hooked it up too. I can't believe he sent this amp to me stock with JJ tubes. Thanks a lot Nik. Well I will soon be posting a sound clip and a Harmony Central review. Thanks a lot every one. Look for me soon posting about other Ceriatone amps.
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cmoore
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« Reply #10 on: August 17, 2009, 12:29:49 AM »

Take a peek at the PI.   Nik may have sent it with a 12AX7, try a 12AT7 and see if that suits you any better.
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Keith
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« Reply #11 on: August 17, 2009, 09:49:59 AM »

No.....I like the crunch I'm getting. I am totally satisfied. No changing.
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