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GK 800RB - new or old?

#22
Ya know, adding a second pair of output transistors to the 100 watt section gets you the exact power section of the rb400, and 4 ohm capability. I'm just sayin...
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Say what?!?!?!?!
Why have I never heard this before? I LOVE my 400Rb, but if I could have an 800 with this mod and run either the 800 or 400 power section, depending on the gig... nice.
 
#23
I have an early to mid 80's 800RB - just can't remember exactly when I bought. It was new in the box when I got it from EU Wurlitzer in Boston - does anyone know how to date them? Grooveman I would love to chat with you about giving mine a tune up - it is making some noise.
 
#25
Vanni said:
It might be interesting this link, on this topic

http://www.talkbass.com/forum/showthread.php?t=142006&highlight=
Daniel Elliott said:
Well you got us there. The LED light is a different color and the knobs are different. Oh and the original one had two output jacks for the High Amp, now it only has one. Hmm, what else is different. The only electronic change was to the DI to add protection from Phantom Power. That was done around 1992. And the Transformer was changed from the square type to a Toroidial type around 99.
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Vanni
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Interesting info that can help narrow it down. Wish I knew how to tell whether my DI was Ph. Pwr. protected. I have a two-output 100 watt section.
 
#27
Standalone said:
Interesting info that can help narrow it down. Wish I knew how to tell whether my DI was Ph. Pwr. protected. I have a two-output 100 watt section.
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Well, I don't see any specific mention of the phantom power issue in my documents. I do see that in 1999 the the wiring on pins 2 and 3 were reversed, but the eco indicates that was to correct an out of phase condition. Perhaps that corrects some issue with the di tolerating 48v.

Well, the quoted post isn't quite correct. There have been more component changes than what was mentioned.

Pots changed through the years, boost swith chip changed, op amps in the crossover changed. Other little changes as well resistors and caps to accomodate pot changes, etc.
 
#28
Oh my, here's a juicy little morsel. I see that in 1995, a change was made to r34, to increase drive current. The eco says the change was because the amp was clipping before full out put...so it appears as if '95 and later might be more powerful. Also, a capacitor was added in 91 across r21 to improve high frequency oscillation.

So it would appear that the post 95 units may be superior.

They got toroids in 99. so those would theoretically be the best ones.
 
#29
Grooveman1961 said:
The newer ones use a more reliable output transistor set, Mj10024,25 as opposed to the older mj10022,23. Higher power ratings.
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I have to correct this one, the bill of materials and schematics that I have, still show the MJ15022,23. Oh hell! I got that wrong as well, I said MJ10022, etc.

Anyway, same out put devices from 82 till 2005 for sure.

I put the mj15024, 25 in my units. Sorry if that caused confusion. I'm sure you were all ripping the lids off to check.
 
#31
Grooveman1961 said:
I have to correct this one, the bill of materials and schematics that I have, still show the MJ15022,23. Oh hell! I got that wrong as well, I said MJ10022, etc.

Anyway, same out put devices from 82 till 2005 for sure.

I put the mj15024, 25 in my units. Sorry if that caused confusion. I'm sure you were all ripping the lids off to check.
Click to expand...

Ishould also mention that the ones I identified as being higher power are actually higher voltage spec'd. Put down your soldering irons.

I just had a big ol cup of coffee. Can you tell?

Ya Know, speaking of differences, I always wanted to know if Mr. Gallien prefered the old crossover that had the 3080's and 351's. After all, there are 353's in other parts of the amp, so he could've chosen those. (new 800's have 353's in the crossover.) Wouldn't just love to hear about the design process he went through?
 

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