Crate V5 mods... anyone?

[cebreez]

Thanks SciHi! I was feeling really alone in here! I understand what you are saying. I didn't see jim p's earlier post and what I'm finding out is the older post seem to lose there pictures. Could just be my crappy computer though. I understand what you are saying but let me interject with a personal observation and please feel free to call me foolish. Like I said I know just enough to be dangerous. I built successfully the "Noisy Cricket" amp and at first was very pleased till I realized for old deaf ears it just was not loud enough and broke up way too soon. I know why and thats okay but before I took the soldering iron back to it I did a little test and plugged it into my pedal board to see how close it was to an overdrive circuit. It just made everything louder, much much louder but did not overdrive or distort the signal at all. Why.... ? My point is I believe the op amp circuit in the Crate V5 is doing exactly the same thing. It is not there to overdrive the preamp tube just to compress and amplify the input signal giving us more headroom. When I changed out speakers I got phenomenal results from a relatively cheap speaker with a bigger magnet. Now i would like to use the input circuit(the op amp) and extend the frequency range (more lows and highs) on command with a better tone circuit. I like the op amp because there is so much you can do in that little space and never have to touch the tubes or drive circuit. Like putting a performance chip in your car or cleaner gas and getting better performance without having to crack open the engine. I hope all this makes sense.... it does in my head but then again that is another matter. HA!

Thanks SciHi....

[SciHi]

... Now i would like to use the input circuit (the op amp) and extend the frequency range (more lows and highs) on command with a better tone circuit. I like the op amp because there is so much you can do in that little space and never have to touch the tubes or drive circuit. Like putting a performance chip in your car or cleaner gas and getting better performance without having to crack open the engine. I hope all this makes sense.... it does in my head but then again that is another matter. HA!

Bent on keeping that opamp, well check out Verne's posts over at HC, "Supercharging a V8." http://acapella.harmony-central.com/...rcharging-a-V8

The V8 is the V5's big brother. First thing Verne did was put in a high quality chip! Replaced the TL072, check it out, and Verne is still around and could help out keeping the opamp intact. You can compare the schematics and see where the V5 cut a few corners to "cheapen" up the amp.

Here is a favorite quote of Verne's:

"The problem with the opamp implementation as found on the V8 – particularly the hiss and extremely low amount of clean headroom – isn’t the USE of an op-amp, but the CHOICE of op-amp. The TL072 is a cheap [20 cents in quantity] component that probably introduces as much noise as using a tube, so it defeats the purpose. Because of its low headroom, it actually introduces a bunch of noise that keeps you from really cranking the gain to its sweet spot.

The “fix” is to replace it with a TLE2072. This is one of Texas Instruments Excalibur series and is renown for being the best of the best. You can get this chip from Mouser for around $2.50. The only complicating factor is that SLM soldered the TL072CN to the circuit board."