Artist/Musician EQ Chip. Question....

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Author Message   Bobzilla Username: Bobzilla Registered: 02-2005 Posted on Friday, October 28, 2005 - 6:37 pm:    Does anyone know... is the "chip" in the EQ systems on the EQ equipped vintage Ibanez guitars the same chip that gives the old Ibanez tube screamers that crunch/power? I was under the impression that it was supposed to be that same chip. The reason I ask is because of two things.... 1) I just had my 2622 set up at the shop. I told the guy, should be same chip in there as the tube screamer chip. Tech says... the chip in mine is not that Tube Screamer chip. 2) I know this Tech, and I know that he recently "retro-modified" his re-release Tube Screamner pedal with the original chip! That concerns me a bit. And... I noticed this too... When you engage the EQ on my MC500NT, man, you have to be prepared in advance for the volume boost. You know... it goes from 10 to about 20! It's a drastic volume jump. Drastic. Not so on the 2622. Engage the EQ and I'd say it jumps from max volume of ten to maybe about 12. Dramatic difference between the volume kick on the mc500 and this 2622 I just picked up. Any insight will be greatly appreciated.   Tim_gueguen Username: Tim_gueguen Registered: 01-2003 Posted on Friday, October 28, 2005 - 7:23 pm:    What you're talking about is an op amp, of which there are a bunch of different types. The chip that gets Tube Screamer nuts all hot and bothered is the JRC 4558D op amp. But in fact the TS808 Tube Screamers could come with other op amps besides the JRC4558D, like the Texas Instruments equivalent TC4558P, while the TS9s often had things like a TA75558 op amp installed. Basically there are a bunch of equivalent op amps that do the same thing, but people find they each sound a bit different in the same circuit. I have no idea what op amps they use in the active Ibanezes.   Michaelkaufman Username: Michaelkaufman Registered: 11-2002 Posted on Friday, October 28, 2005 - 9:38 pm:    Actually, I don't think the 'eq' is an 'overdrive' like the TS808, etc. It's really supposed to be an an eq: boost or cut certain frequencies. In the Ar-500 (besides the 3 eq bands), you also can boost or cut the overall volume at the flick of a switch. I'm not sure how the 2622 works as it has less knobs.   Munch Username: Munch Registered: 02-2001 Posted on Saturday, October 29, 2005 - 5:02 am:    Hi Bob, My 2622 has massive amounts of boost on tap - to my ears its exactly as you describe the MC500 you have. The knob on the 2622 that you would think to be a passive master tone control is actually the gain control for the EQ. If you max this knob out and you don't hear gobs of volume and distortion, then something is wrong. It could very likely be this pot - I had to replace mine due to bad crackles and loud pops. It the pot checks out, then I'd suspect something in the EQ circuit. If it is the circuit, Spiro has posted some circuit diagrams and photos on this site previously. Cheers, Mark   Bobzilla Username: Bobzilla Registered: 02-2005 Posted on Saturday, October 29, 2005 - 9:05 am:    Thanx gentlemen. I know how all the controls function on both the mc500 and the 2622. The scenario I was describing above was with both the main volume and the EQ volume controls set on max., on both guitars. So... with such a drastic difference between the jump on both guitars, I think I should have it looked into. Unless.... there's two different "op amps" as described above, and that's having something to do with it. Even though the 2622 "jump" is far less than the mc500, nonetheless, it seems to be functioning fine, other than the noticeable difference between the 2 guitars. If I didn't own the mc500, I probably would have thought the 2622 is functioning fine. It actually might be. But.... I don't know.........   Strings Username: Strings Registered: 01-2005 Posted on Saturday, October 29, 2005 - 4:27 pm:    FYI to all - On my 2622, If I have my boost/cut control at zero and all 3 EQ knobs at center, I get about zero diference toggling in and out of the circuitry...the way it ought to be ;O) MK - The only "less knobs" from 2622 to AR500 is a master tone pot on the 500 (and the trisounds, of course)...'tsit.

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