Sledgehammer... not a good idea, the cab in itself is alright.
Sledgehammer... not a good idea, the cab in itself is alright.
Gretsch Corvette
Parker P-38
Yamaha APX500
Vox Pathfinder 15R
Vox Tonelab ST
Blackheart LG
... That's it.
Have you ever worked on tube amps before? Do you have a DMM? Do you have a schematic for the amp?
I believe the V5 is the same amp as the VC-508, but with different cosmetics.
I've never seen the inside of one, so it may be hard to mod if there are SMDs on the PCB.
tung
- Dave Lizewski, Kick-A$$I was just a regular guy. My only super power was being invisible to girls.
Nop, not a licensed tech or anything... i consider myself a good tinkerer and good with a soldering iron, but i could never come up with the slightest idea on how to mod a tube amp.
That's why i'm waiting for some mod-kit to come up (with instructions), that i can manage. BTW, i'm aware of the dangers involved in tube amps, and know the right proceedures for a proper drain.
Schematics i don't have but i'll start working on getting those (never dealt with Crate people).
As of now, i only have some pics of the amp's board (if that gives any help).
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Gretsch Corvette
Parker P-38
Yamaha APX500
Vox Pathfinder 15R
Vox Tonelab ST
Blackheart LG
... That's it.
A few more pic's of the Crate V5...
Sovtek tubes...
And here, the 99 dollar cab and crappy speaker...
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Gretsch Corvette
Parker P-38
Yamaha APX500
Vox Pathfinder 15R
Vox Tonelab ST
Blackheart LG
... That's it.
The good news is that it looks like there are no SMDs on the board.
One thing I would check is the bias. If the schematic I have is correct, the cathode bias resistor is only 100 ohms. It seems like it should be bigger.
You will want to check the plate voltage as well.
What are you trying to accomplish by modding your amp?
tung
- Dave Lizewski, Kick-A$$I was just a regular guy. My only super power was being invisible to girls.
The amp lacks of bass tones, and the overdirve is kinda fuzzy. the volume range jumps drastically when dialed between 6-7... cleans are ok.
The tone knob is really wierd... seems to be a -10/0/10 kinda knob where turning it from one end to the other (0 to 10) the tone at 0 seems be down, then go up at the middle (5) then down again when reached 10 (dunno if i explained myself).
I've read a few other reviews were changing the speaker and tubes helped for some, but others claim that not even that helped (i don't have extra speakers nor tubes to try this out).
So basically the mods consist in providing some bass to the amp and making the tone knob work correctly.
Gretsch Corvette
Parker P-38
Yamaha APX500
Vox Pathfinder 15R
Vox Tonelab ST
Blackheart LG
... That's it.
Just to make sure I'm looking at the same schematic, what value do you have for R17? On my schematic, it is a 100 ohm, 5 watt resistor.
The circuit should have plenty of bass. I would guess that it is a combination of the 10" speaker and a small output transformer. I wouldn't know what to recommend for a replacement, it depends on how much real estate is on the chassis, and how the OT is connected into the circuit.
The volume control is kind of weird. On my schematic, it is a 10k linear pot. On most circuits this control is 470k to 1 meg ohms and would be an audio/log pot.
The tone control looks like a modified Baxandall to me, but I could be wrong. It definitely isn't the treble cut tweed type that I'm familiar with.
The input gain stages is a cascaded opamp. A TL072. Any of the replacements will give you slightly differing results. I would pull the stock opamp and put in a socket so you can swap them out easy. I believe the TL072 is pin-compatible with the Tube Screamer types. You might even want to spring for a spendy Burr-Brown type.
tung
Originally Posted by Tarin
- Dave Lizewski, Kick-A$$I was just a regular guy. My only super power was being invisible to girls.
Where did you find a schematic for this amp?Originally Posted by tunghaichuan
FWIW, I am getting to the point where I might just replace the whole schematic with a hand-wired replacement. If possible, I wanted to just replace the tone stack (I doubt the solid state components are entirely to blame)...but I also believe the guy who said he replaced the entire circuit (save the tubes and transformers).
I was hoping for a glance at the schematic before I rip the guts out).
Thanks in advance for any help on this.
Right here: http://www.thefret.net/showpost.php?...2&postcount=28Originally Posted by chris2002rock