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Posted: Fri Jul 23, 2010 6:59 am
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Thanks 63supro. Another stupid question - what is a Class A amplifier? Is this a good or bad thing, or just an arbitrary name based on circuit design? Does the HRDlx qualify?


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Posted: Fri Jul 23, 2010 8:43 am
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suddentwigs wrote:
Thanks 63supro. Another stupid question - what is a Class A amplifier? Is this a good or bad thing, or just an arbitrary name based on circuit design? Does the HRDlx qualify?


It gets a little complex at this point, but a HRDlx is not a Class A amp.
Here is an article I found explaining it.

http://www.mesaboogie.com/US/Smith/Clas ... ersion.htm

Class A amps are fun but very inefficient and sound incredible and have a very complex tone. The explanation is too lengthy to put here and would possibly bore you to tears.

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Posted: Fri Jul 23, 2010 12:48 pm
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Thanks everyone for the replies, its a HUGE help. i'm gonna keep lookin around, but I think im liking the GrOoVeTuBeS as of now

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Posted: Fri Jul 23, 2010 1:57 pm
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rubyinthedust88 wrote:
Thanks everyone for the replies, its a HUGE help. i'm gonna keep lookin around, but I think im liking the GrOoVeTuBeS as of now


Ouch! :shock:

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Post subject: Tube change
Posted: Fri Jul 23, 2010 2:08 pm
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Hey rubyinthedust88,

Hang on to your "old" tubes and keep them in the boxes that your new ones come in, if you do get new ones. You just might find that those "old" ones are ok.

I didn't really ask you why you thought that the tubes need to be changed when you said that it's really starting to affect the tone quality. There are other things that you can do about the tone, it could be capacitors or some heat related issues. 63supro can probably tell you of some other issues you might want to consider in the Hot Rod Deluxe.

Don't void your warranty, I think that it is five years. But you can at least "look" in the amp for signs of other problems. With the amp unplugged from electricity, carefully remove the 6 silver screws on the back panel and remove the back cover and look inside, don't touch anything inside the chassis because there could still be an electrical charge. The cover may be tight on both ends, but it will come off. If you see any evidence of heat damage or anything unusual, or bad solder joints (if you know what that means :lol: ), button it back up and take it back to the dealer and tell him what you find. Tell them about the sound quality and see if you can get them to go through the amp and fix it. You might suggest to them that you want the solder joints and capacitors checked, and the bias set correctly. There is an adjustment that they can use, so it would be very easy for them to do. Make sure that you puff up your chest before going into the dealer and be firm and almost demanding with them, so they don't try to weasel out of anything. They might also have to "send it somewhere else" for repair, so it might take a while.....(no amp for you!) But if you don't have the receipt for it, or for some other reason you don't have a warranty, then all bets are off. :D

But, hopefully if all seems well inside the amp and you just want to try some new tubes, go for it and definitely let us know what your experience is.


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Posted: Fri Jul 23, 2010 2:59 pm
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good description

i gotta friend with a super 40, and it sounds great when it starts breaking up, but it sounds good .
he uses a TTE with it and a leslie cabinet too~

but yeah, pushin' that clean channel into breakup territory is where it is....

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Posted: Fri Jul 23, 2010 5:11 pm
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Interesting stuff, 63supro. Clearly a thing to be investigated for the eventual collection. However, details on the interweb are sketchy about what amps are class A - I have learned the Vox AC30 isn't (though everyone thinks it is), but which ones are?


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Post subject: Class "A" amps
Posted: Fri Jul 23, 2010 6:02 pm
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Most amp designated Class "A" have CATHODE BIASED power tubes. I have two Matchless amps which are Class "A." A Spitfire (two EL84) and a Chieftain (two EL34). Both have cathode resistors tied to ground with cap bypasses.

Most Fenders (except those single ended Champs, and some tweed Deluxe and Princetons) are FIXED BIASED and set to Class AB1 parameters. They have a fixed negative voltage (BIAS POWER SUPPLY) applied to the power tube grids. Adjusting this supply alters the set (thus "FIXED") negative voltage on the grid and thus the idle bias of the power tubes.

Tone is completely different betweem the two models of biasing. I have seen and heard some Fenders which have both FIXED and CATHODE biasing. And yeah, I guess you can say that the tone is somewhere in between the two.


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Posted: Sat Jul 24, 2010 9:30 pm
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Supro, that is a great article, touches on alot of important subjects ! Thanks ! Art

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Posted: Sun Jul 25, 2010 5:16 pm
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Groove Tubes are beyond AWFUL in my opinion and sound so harsh.

JJ's are the best tubes for these amps. Hands down.

CC

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Posted: Sun Jul 25, 2010 5:54 pm
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Celtic Cyclonus wrote:
Groove Tubes are beyond AWFUL in my opinion and sound so harsh.

JJ's are the best tubes for these amps. Hands down.

CC


Hey CC hows it goin man... I biased my Groovy tubes to 85... a world of difference from the factory setting! Still Im really wanting order the Blues kit from EuroTubes... Any thoughts?

Bill

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Posted: Sun Jul 25, 2010 6:10 pm
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Here's some additional notes on Class A amps......

http://www.aikenamps.com/ClassA.htm

Arjay

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Post subject:
Posted: Mon Jul 26, 2010 5:42 am
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bill948 wrote:
Celtic Cyclonus wrote:
Groove Tubes are beyond AWFUL in my opinion and sound so harsh.

JJ's are the best tubes for these amps. Hands down.

CC


Hey CC hows it goin man... I biased my Groovy tubes to 85... a world of difference from the factory setting! Still Im really wanting order the Blues kit from EuroTubes... Any thoughts?

Bill


Bill, it's up to you but I'd back off the GT's a little. Unless you want some new JJ's. :wink: My GT's gave up the ghost at 72mv. The GT's were horrible. They were re-branded Sovtek 5881's. They pretty much sucked no matter where I biased them. My JJ's on the other hand were biased at 85mv with no problems. Bob at Eurotubes says they can go as high as 95mv. I tried mine at 90mv and it broke up a little too early for my taste. YMMV

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