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Old 3rd March 2014, 05:44 AM   #1
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Default Carr Rambler

Has anyone been inside one of these?

Why I ask is because my friend is going to purchase one and the price tag is pretty heavy. I have never played through one but my buddy keeps on saying it's class A and of course I said guitar amps are pretty much never truly class A but Carr's website states that it is a class A design yielding 28 watts from a pair of 6L6GC's. This kind of sales pitch always rubs me the wrong way when amps are cathode bias people think they are class A. I couldn't find a schematic online but I did find a post on another site about someone who took some readings of his rambler and posted the results. The readings were 380 plate volts and 50mA of idle current.

My thoughts were that a 6L6GC class A PP amp would run at a lower plate voltage and higher current, somewhere around 300 plate volts and 100mA putting out under 20 watts of power. Even if the amp is class AB it seems to be biased cold for a cathode biased amp.

I don't want to burst my buddies bubble or anything but I don't trust amp builders who don't know what they are talking about.
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Old 3rd March 2014, 05:55 AM   #2
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PS: The front end of this amp is supposedly the similar to a Deluxe Reverb so I am guessing around 40v grid to grid signal going to the power tubes so the bias of around -25v would put this amp in class AB.

Last edited by famousmockingbird; 3rd March 2014 at 06:05 AM.
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Old 3rd March 2014, 08:48 PM   #3
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I don't know anything about this particular amp. Class A has a strict meaning.....and a guitar amp interpretation, you know the "my Vox AC15 is a class A amp" kind. I suspect that this falls into the same category.

It IS possible to build a class A amp using 6L6GC's with 380 volts on the plate, 270 on the screen, cathode bias with 50 mA PER TUBE idle current, and get around 20 watts while still remaining in class A. The plate load impedance would need to be somewhere north of 16K ohms which is very unlikely due to the complexity of the OPT.

I tried something similar, using a 6600 ohm OPT wired for 13200 ohms, slightly less B+ and more current. I didn't like the sound.

I wound up using the same 6600 ohm OPT (I have lots of them) with about 325 volts on the plate and screen and about 75 mA per tube. It worked much better. If I remember the power was about 20 watts.

Remember this, even a true class A amp isn't class A any more when you plug in a stomp box and drive it well into clipping.
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Old 3rd March 2014, 11:01 PM   #4
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Bottom line question "is the tone worth the dollars?"
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Old 4th March 2014, 12:49 AM   #5
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Thanks Tubelab for you knowledge and insight.

I figured about the same that if it is class A it would be just under 20 watts and not his rated 28. And yeah a much larger plate load would be needed than the usual 6600. I am thinking it too falls under the same category of "my ac15 is class A".





Quote:
Originally Posted by djgibson51 View Post
Bottom line question "is the tone worth the dollars?"

This is the real question, and sounds like I will find out very soon.



I built him a tube preamp for his Guild Artist Award guitar so he can just plug into PA's and have it sound good and have tone controls etc. He also already has a Hard Truckers 2x12 cab with Tone Tubby alnico drivers in it. I am trying to convince him to let me build a power amp for about 1/3 of the price of the Carr but I think he has his mind made up. If he gets it I will give it a workout and maybe open it up and let you boys know what I think. Also since there is no schematic to be found on the interwebs I might take the time to draw one up
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Old 4th March 2014, 03:29 PM   #6
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Quote:
I am trying to convince him to let me build a power amp for about 1/3 of the price of the Carr
I learned a long long time ago that this will never work. Even if you took the guts out of whatever your friend wants and stuck it in a different case, your friend will always say that it sounds "different." Never mind that the one he buys will sound "different" than the exact same amp played in the guitar store....or anywhere else.

I thing the only "clone" that I ever made that was a big hit was the copy of a Vox Tone Bender / Dallas Arbiter Fuzz Face that I made for a friend back in 1969. I wound up making about a dozen of them. Still have mine.
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