Crate V5 mods... anyone?

[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."

[cebreez]

Awesome.... Im checking it out now! Thanks SciFi!!

[jim p]

A big problem for headroom in the V8 is the power supply for the op amp is only +/- 8volts so you can have clipping with low gain on the op amp. The V5 has +/-15 volt rails and you could up them to +/- 17 to 18 volts no problem if you want. I think any op amp is going to change the tone with approx 30 transistors and feedback inside the op amp it is not the same as going straight into a tube. The V5 is the V8 but using the gain control as the volume control and removing the volume control and line out.

[cebreez]

Yeahhhh.......... well....... I totally agree with you!!! I really do! Does make you wonder why the "geniuses" put it there to start with. Seems like a big waste of time and money. Honestly in the end I will probably do exactly what you are suggesting but in the meantime Im going to see what kind of fun I can have with this. Like you did...

[cebreez]

Anyone wanting to relive this discussion. Im starting my mods any day now. The new thread will be here: http://www.thefret.net/showthread.ph...-will-commence!

[nbs2005]

Hi, Trying to bring this back from the dead. I want to do the mod described by deafelectromark which is about the skill set I have. (OK, that might be more than I have). I'd really like to see some of the pictures that were posted for that back in the day and are now dead links. It would really help me in my project.

BTW, this has been a great thread.

[marnold***]

Hi, Trying to bring this back from the dead. I want to do the mod described by deafelectromark which is about the skill set I have. (OK, that might be more than I have). I'd really like to see some of the pictures that were posted for that back in the day and are now dead links. It would really help me in my project.

BTW, this has been a great thread.

I think you may be out of luck since he hasn't visited The Fret in over seven years. You could try emailing him via his profile and hoping against hope that he has the same email address.

[nbs2005]

I sent him an email. It did not bounce, but I haven't heard anything back either. If anyone has done this mod and is still on the board, I'd greatly appreciate a picture of the work done.

Thanks,

J

[nbs2005]

Hey all, one more update. I took the v5 to Steve Moratto, he's an amp builder in Ajax just outside of Toronto. For $125 Canadian, he turned this into a pure tube tone monster. That included new pots. He's a great guy with a great reputation in Ontario. You can reach him here http://www.morattoampshop.com/ And no, I'm get nothing for this; just wanted to promote a fellow Canadian.