Crate V5 mods... anyone?

[jim p]

Another way to modify the amp would be to use the tone pot for a volume pot and the volume pot for a gain pot. This involves no cuts just jumpers and removing components with one being replaced (C24)
1) Remove PCB from chassis
2) Remove R13 C26 C24( to replace with 47nf for more bass or keep as is if you wish) C6 C5 C4 and R27
3) Replace C24 with a 47nf
4) Jumper junction of C6 C5 and CW2 (tone pot) to junction of R27 and R15
That’s it now the volume pot will control the gain of 2nd stage op amp for overdrive and the tone pot will control the volume.

[Big K]

Outstanding information!!!! But it makes my head hurt and tempts me to switch from coffee to vodka this morning with all the electrical theory.. I thought being able to solder effectively enough to swap out switches, pots and pickups made me feel like a genius when it all works but you amp modder guys are on a whole nother level : : : :
Thanks for all the shared information!

[tunghaichuan***]

Just as a heads up, I got the new flyer from Guitar Center with the V5 priced at $79. My flyer came with a 10% off coupon, so the V5 is a pretty good deal from GC right now. :

tung

[jim p]

What to do with the stock V5 speaker? Now I hope you aren’t going to sell it to someone so why not use it as a testing load for the amplifier. I put one of those cheep ¼ inch cables on it packed some fiberglass around it and put it in the box the amp came in. So now instead of just looking at the output with a resistor as a load I have a speaker instead. There is quite a difference in the waveforms on the scope between the resistor and the speaker. With a square wave you can see overshoot with the speaker you do not see with a resistor. Also you won’t drive everyone crazy (cats, dogs and neighbors)

[jim p]

Has anyone made the supply a choke input yet, just want to know exact voltage they are getting at C15+. I may want to make the same mod on one of my amps. This would also free up Junction of C16 R26 and R25 as the decoupling for the second triode. Also if the voltage is low enough can leave the screen grid connection stock.
Found with the volume control after the tone stack at minimum you still get signal at the output of the amp. I think this is due to not having separate decoupling on both the first and second triode. So being able to move R6 to the other side of R26 would cure this as long as it is not used for the screen grid.

[goonrick]

Has anyone made the supply a choke input yet, just want to know exact voltage they are getting at C15+. I may want to make the same mod on one of my amps. This would also free up Junction of C16 R26 and R25 as the decoupling for the second triode. Also if the voltage is low enough can leave the screen grid connection stock.
Found with the volume control after the tone stack at minimum you still get signal at the output of the amp. I think this is due to not having separate decoupling on both the first and second triode. So being able to move R6 to the other side of R26 would cure this as long as it is not used for the screen grid.

Haven't done it yet, as I'm waiting on some components to ship. I'll be sure to post what voltages I get when I do though.

[goonrick]

Jim,

I did the choke input mod and am getting 296V at C15 plus. Is that about what we were shooting for?

[Christopher Whitlow]

Another way to modify the amp would be to use the tone pot for a volume pot and the volume pot for a gain pot. This involves no cuts just jumpers and removing components with one being replaced (C24)
1) Remove PCB from chassis
2) Remove R13 C26 C24( to replace with 47nf for more bass or keep as is if you wish) C6 C5 C4 and R27
3) Replace C24 with a 47nf
4) Jumper junction of C6 C5 and CW2 (tone pot) to junction of R27 and R15
That’s it now the volume pot will control the gain of 2nd stage op amp for overdrive and the tone pot will control the volume.

I introduced myself a moment ago in the newbie section.
Got this amp free on a trade with an Emminence Legend and JJ tubes. Really want to do this simple mod first, has anyone completed it yet? This is my first tube amp and it was free so what the heck right?
I only have one question, would a 12aT7 work for me to lower gain a tad? I just want a tad more headroom with a bit less gain. The loss of tone control doesnt really bother me, thats why I put nice CTS pots and treble bleeds in my guitars and my pedals all have tone knobs!
Jim and the others... wow! great info thanks so much for posting all the replies!

[tunghaichuan***]

I only have one question, would a 12aT7 work for me to lower gain a tad? I just want a tad more headroom with a bit less gain.

Welcome to the forum.

If you want a lower gain 12AX7, try a 5751 or a 12AY7/6072.

The 12AT7 isn't a lower gain 12AX7, it has different specs and operation points. Other than sharing the same pinout and dual triode configuration, the two are more dissimilar than similar.

Having said that, there is nothing wrong with trying a 12AT7. It won't hurt anything, and who knows, you might even like the tone.

[Christopher Whitlow]

Welcome to the forum.

If you want a lower gain 12AX7, try a 5751 or a 12AY7/6072.

The 12AT7 isn't a lower gain 12AX7, it has different specs and operation points. Other than sharing the same pinout and dual triode configuration, the two are more dissimilar than similar.

Having said that, there is nothing wrong with trying a 12AT7. It won't hurt anything, and who knows, you might even like the tone.

Hey there! Thank you for giving me options to look into and thank you for the welcome.

[Chris Paul]

Just did this mod today and it was well worth the time and effort! Thanks a ton JimP

[Christopher Whitlow]

Sorry for the the post earlier, I was on a different account. The tone/volume mod is super easy and just what I needed. I am just learning the finer points of soldering and was a bit leery of the PCB board due to the small parts and all that. Well it went real easy with exception of clearing out solder on a couple spots. All my soldering experience has pretty much been guitar pots, switches, and repairing cables. Oh, and I can "sweat" a pipe too I have a handful of very nice pedals and really dont need the amp to have tone control...for now. I am very pleased with how this amp sounds! I played every small valve amp I could get my hands on in the last couple years and this one was on the bottom of the list as far as sound quality goes. Now it sounds IMHO better than my friends stock Vox with tube upgrades by a long shot and I liked his amp a lot.

Now I have a follow up question of sorts. I feel as though the highs are too sharp even through my "darkest" guitar. I am wondering if there is a resistor or cap that can be swapped out to tame the "ice pick" a bit. I already have a home made treble blocker installed behind the grill, which does help, but I would like to run the amp with just a tuner and a wah and not feel like I need my EQ. Thanks again all who made this thread what it is!

[Christopher Whitlow]

Quick question about the sweep of the volume pot. I have done the above mod and now would like to know if there is a to slow down the sweep of the volume pot. This little dude is loud! Friend of mine uses my Cube 30x when he comes over and the 5watt tube is every bit as loud as the Roland. The amount of volume isnt really a problem, Its how fast it get loud that is hard to deal with. At 1 1/2 to 2 it starts coming on real loud and seems to top out at 7-9 on the dial. Can I use a different value pot like I have done in guitars or is this a more complicated fix? I really need to be able to play at actual bedroom volumes and I cant afford a hot plate so I am hoping I can slow down the sweep so that 0 thru 3 or 4 are usable in the house when others are watching the tube. Thanks all!

[tunghaichuan***]

Quick question about the sweep of the volume pot. I have done the above mod and now would like to know if there is a to slow down the sweep of the volume pot. This little dude is loud! Friend of mine uses my Cube 30x when he comes over and the 5watt tube is every bit as loud as the Roland. The amount of volume isnt really a problem, Its how fast it get loud that is hard to deal with. At 1 1/2 to 2 it starts coming on real loud and seems to top out at 7-9 on the dial. Can I use a different value pot like I have done in guitars or is this a more complicated fix? I really need to be able to play at actual bedroom volumes and I cant afford a hot plate so I am hoping I can slow down the sweep so that 0 thru 3 or 4 are usable in the house when others are watching the tube. Thanks all!

The problem with the pot isn't the value, it's the taper. If your volume is coming up to fast, then it is most likely a linear taper pot. What you want is a log or audio taper. It may or may not be hard to find in the right value. What is the value?