#1
I have a Crate v18. It's a really cheap tube combo. I'd like to try and make it sound a little brighter and fender like. I'm considering adding the same tubes as a '57 twin-amp, GT-6L6 power and 12ax7 pre. It comes with 2 el84 power, and 3 12ax7. My question is how much will it change the amps characteristics, tone, feel, etc... Obviously the 12ax7's will be of higher quality if I get replacements.

Or would altering the wiring, resistors, and all the little stuff instead of the tubes have a bigger influence on the sound?

I'm looking to stay under $100, but as long as it's not too much over, I can make do.
Guitars
Gibson SG '61 Reissue 'Aretha'
Fender MIM Strat 'Rosy'
Takamine EG 332c 'Betsy'
Epiphone G-400 'Lucy'

Amps
Crate V-18 1x12
Roland Cube 30x


Pedals
Dunlop Original Crybaby
Electro-Harmonix Double Muff
Line 6 Echo Park
#2
Changing pre-amp tubes would create the biggest change, I believe. Changing speakers would also change things up, but I wouldn't invest that kind of money into a cheap tube combo. As for the power tubes, make sure that you adjust your amplifier's bias, el84s and 6l6s have different currents. Another big tone changer is upgrading output transformers, but that is rather expensive.

Best of Luck
#3
I have a V18 as well. If you have the 1x12 the first thing I would suggest is buying a Weber ceramic Silver Bell or Blue Dog for $120 after shipping; those speakers are phenomenal. I have one of each running in my 2x12, 30W undoped. Just email the company and they'll help you out. The Blue Dog will give more of a Voxy chime and the Silver Bell gives more of a Marshall crunch, but they're both voiced very similarly, the Silver Bell's just a bit more bassy and the Blue Dog a bit more chimey. http://www.tedweber.com/

If it's the 2x12 then I'd probably go with a tube change first then save up to change the speakers. The tubes I have running right now I got from Doug at dougstubes. V1 is an Electro-Harmonix 12AY7, V2 is a JAN GE 5751, and V3 is a balanced JAN Philips 12AT7WC. For power tubes I got a matched pair of late breakup JJ EL84s. All of this greatly increased the headroom of the amp and gave it a more singing quality, cost about $80 or so I think. Make sure you clean the pins with some contact cleaner or denatured alcohol to make sure there's good contact and reduce noise. The NOS tubes especially should be cleaned. http://www.dougstubes.com/

If you want to alter the circuit there are a lot of mods you can do, some you won't even need to buy components for. First you can try swapping R4 and R10, that will decrease the gain a bit. If you want to open up the tone a bit and make the amp more dynamic and responsive you can remove R6 and leave nothing in R10 and jumper it from where the right leg of R6 was to where the left leg of R10 was. This removes the little tone stack between V1A and V1B. To bump the gain down more you can remove the cathode bypass capacitors (C6 and C13) on V1A and V2B. I also changed R5 to about 4.4K (I used three 1.5K resistors in series) and R12 to 100K to cut the gain on V1B. After these mods and tube changes the gain knob is useful in its full range. You might not want quite as much gain cut, just do mods one at a time and see what you like. If you want to make the tone stack more responsive change the slope resistor (R18) to 100K, definitely recommend this one. All of these mods can be done topside, but would be easier if you want to take the board out, probably a little safer since you won't need to heat the PCB as long. And as always, remember to drain the filter capacitors or you'll be in for a nasty surprise.

I've spent about $530 total on this amp with speaker changes and tube changes and buying the amp itself and I think it was worth it. I now have a sound that I feel is much better than $500 amps like the Blues Junior, and most certainly better than the V18 is from the factory. I've also heard changing to a full-size reverb tank (accutronics 4EBC21B) can provide a big improvement for the reverb and I'm sure the OT could be improved on, but I haven't tried those.

Pics to aid you (don't ask why some are rotated, imageshack just did it randomly).





















And the corrected drawings for the innards. http://www.blueguitar.org/new/schem/misc_amp/crate_v18_corrected_drawings_v2.pdf

Good luck!

Edit: If you want sound clips I can try to get a good microphone from my school, I just don't have a mic right now besides my crappy webcam.
Last edited by Mike-T93 at May 26, 2010,
#4
Wow, thanks both of you. I woudn't have put in that much work on a school project, but you did for UG. This site is awesome, and occasionally so are the users.

It is a 1x12 too.
Guitars
Gibson SG '61 Reissue 'Aretha'
Fender MIM Strat 'Rosy'
Takamine EG 332c 'Betsy'
Epiphone G-400 'Lucy'

Amps
Crate V-18 1x12
Roland Cube 30x


Pedals
Dunlop Original Crybaby
Electro-Harmonix Double Muff
Line 6 Echo Park
Last edited by rhcpjhlz at May 26, 2010,
#5
Mmm, I'd just go with the speaker change and some circuit mods for now then. The tubes will need to be changed eventually, anyway, and as such should be considered a maintenance cost. As long as the cheap Sovteks in there aren't microphonic or overly noisy you can get some nice sounds while you wear them out. It just won't quite have that Voxy chime without JJs and your clean headroom is be a bit lower. The heavily-doped, lifeless speaker has to go, though. I'll A/B some soundclips of the two speakers if I can get a mic.

Edit: I just reread the OP and I thought you should be aware it won't sound very Fender-like no matter what you do to the circuit, but if you want to make it brighter you can definitely make it Voxy. I'd probably go with the Blue Dog if brightness were my main concern. I put the Silver Bell in so it would still have some serious balls on the low end. Of course you could try one of their more American-voiced speaker offerings, but since you're stuck with EL84 power tubes you might as well not fight it and go British.
Last edited by Mike-T93 at May 26, 2010,
#6
I had to replace the speaker already a while back. I dropped the amp and the magnet came off the speaker or something. Anyways, I have a celestion hi watt in there now. It's better and seems like it has a little crisper distortion, but a little warmer clean. I should have said that in the beginning, my bad.

With that though, the amp is a little short of two years old so I imagine the tubes could go kinda soon anyways since they are what came with it. You say I'm stuck with el84's, is that cause you think i should change the speakers, or is it not possible to switch to another type of tube? I've never messed with a tube amp before as this is my first.

I will probably mess with the circuitry now then. Where would I acquire the parts you mentioned in your previous post?

And thanks again, very helpful!
Guitars
Gibson SG '61 Reissue 'Aretha'
Fender MIM Strat 'Rosy'
Takamine EG 332c 'Betsy'
Epiphone G-400 'Lucy'

Amps
Crate V-18 1x12
Roland Cube 30x


Pedals
Dunlop Original Crybaby
Electro-Harmonix Double Muff
Line 6 Echo Park
#7
It would be easier and more worthwhile to build a new amplifier than modify a V18 to use 6l6 tubes. Amps are kinda built around their output section.

I would go ahead and buy the new tubes since you already have a decent speaker and your power tubes are aging. Nothing really beats Weber speakers, but the cost wouldn't be worth it for the minimal improvement unless the current speaker is totally voiced the wrong way.

As for the resistors, you can get those at Radioshack. If you haven't ever soldered anything before you'll need to get a pencil-tip soldering iron and some solder. You also should look up some videos on how to solder and practice outside the amp first. Other tools you need are needle-nose pliers and some snips.

Edit: Keep the old tubes lying around as spares when you get the new ones, it can't hurt to have them just in case.
Last edited by Mike-T93 at May 26, 2010,
#8
Alright, I'm just gonna use the tube guide on here for picking the most appropriate el84s then, unless there are any recommendations.
The speaker was a big improvement from the stock and I can't afford to spend too much so I'll just stick with what I got.
I've soldered before and have all the tools so thats covered.

Whenever I do get it all done, if you're interested I can let ya know how it goes.

Thanks

edit: After looking through the guide and some reviews, the JJ EL84's seem to be the way to go for the power section.

I'd like to put the tung sol 12ax7's in the pre amp, but it says don't do it if their is a cathode follower stage. I've read that this amp is cathode biased. So are these trouble or would it be ok?
Guitars
Gibson SG '61 Reissue 'Aretha'
Fender MIM Strat 'Rosy'
Takamine EG 332c 'Betsy'
Epiphone G-400 'Lucy'

Amps
Crate V-18 1x12
Roland Cube 30x


Pedals
Dunlop Original Crybaby
Electro-Harmonix Double Muff
Line 6 Echo Park
Last edited by rhcpjhlz at May 26, 2010,
#9
if you don't have much to spend, i suggest messing with the circuitry. if you know what you're doing, and have the right tools, it'll turn out better. just make sure you know what everything does. so far in this thread, you haven't mentioned how you want to alter the sound have you? first thing to do is switch the output tubes (maybe preamp tubes too). then see if you like it, and build a list of improvements you want in terms of sound.
Call me "Shot".

ShotRod Guitar Works

Custom Hand-wired Amplifiers and Effect Pedals.

Est. 2007


Source to everything I say about Guitars, Pedals, and Amplifiers: I make them.


UG's Best DIY PedalBoard
#10
@ECisthebest, I'd like the amp to be a little brighter with cleans. The breakup is fine and I'm not overly picky with my overdrive's, but the clean is too dark and mellow for me. I was hoping to get more of a fender sound out of it, but miket93 is saying vox is more likely.

I definitely will mess around with the circuitry soon and find what works for me. Then hopefully the Power tubes, and finally the preamp tubes.
Sound Good to you guys?
Guitars
Gibson SG '61 Reissue 'Aretha'
Fender MIM Strat 'Rosy'
Takamine EG 332c 'Betsy'
Epiphone G-400 'Lucy'

Amps
Crate V-18 1x12
Roland Cube 30x


Pedals
Dunlop Original Crybaby
Electro-Harmonix Double Muff
Line 6 Echo Park
#11
Would a sovtek 5751 work? You say I can't go from el84 to 6l6, well how about 12ax7 to 5751?
Guitars
Gibson SG '61 Reissue 'Aretha'
Fender MIM Strat 'Rosy'
Takamine EG 332c 'Betsy'
Epiphone G-400 'Lucy'

Amps
Crate V-18 1x12
Roland Cube 30x


Pedals
Dunlop Original Crybaby
Electro-Harmonix Double Muff
Line 6 Echo Park
#12
Yeah, that sounds about right. Old power tubes get dull and lifeless and JJs are brighter than Sovteks out of the box, so that'll definitely be an improvement. Do the circuit mods to your liking (remember the component values are guidelines and you can do anything similar as long as it's not too far off) and change the preamp tubes according to the sound you get after the mods. You kind of fine-tune the sound with different tubes, not reshape it. You should also keep in mind that you can use 12AU7, 12AY7, 12AV7, 12AT7, 5751, and 12AX7 tubes interchangeably to change the gain and character of the preamp. In mine V1 is an Electro-Harmonix 12AY7, V2 is a JAN GE 5751, and V3 is a balanced JAN Philips 12AT7WC. I get fairly light distortion even when cranked with this combination, it really stays clean up to 6 on the gain knob with humbuckers.
Last edited by Mike-T93 at May 26, 2010,
#13
first thing i would do to reduce the gain is lowering R7 to 100k. it has 221k for the anode load resistor, which is way too much. i would also short R34, maybe even short R8 to have the HT for preamp tubes at around 270v? then bias each tube, V1A, V1B, V2A, V2B at center, it should be around 1k5 for the cathode resistor. remove bypass caps to your likings. after those, if theres too little distortion now, raise R43 to maybe 221k. (standard value is 220k tho.)

another thing i noticed, NO triodes in the preamp have a gridstopper on them. that's going to add a lot more RF.

cleans being too warm, raise the slope resistor (R13) to 56k or 68k. 56k will give you the traditional marshall tonestack, BUT marshall's tone stack was after a cathode follower. (low output impedance) and that's why the 56k worked. with a regular triode gain stage, i would suggest raising R13. maybe even 100k. bigger gives you less mids + bass.

you could also add a bright cap on the gain knob, but it won't affect if you play with the gain all the way up. and likewise, it'll make your overdrive a little brighter. to tame the high end, put 1n~3n3 caps across R2, R7, R40, and R42. that'll get rid of annoying highs if you get any of that.


you can't do any of these unless you try them. so good luck, and be safe.
Call me "Shot".

ShotRod Guitar Works

Custom Hand-wired Amplifiers and Effect Pedals.

Est. 2007


Source to everything I say about Guitars, Pedals, and Amplifiers: I make them.


UG's Best DIY PedalBoard
#15
i'm looking at this schematic:

http://www.blueguitar.org/new/schem/misc_amp/crate_v16_palomino.pdf


Quote by ECistheBest
first thing i would do to reduce the gain is lowering R7 to 100k. it has 221k for the anode load resistor, which is way too much. i would also short R34, maybe even short R8 to have the HT for preamp tubes at around 270v? then bias each tube, V1A, V1B, V2A, V2B at center, it should be around 1k5 for the cathode resistor. remove bypass caps to your likings. after those, if theres too little distortion now, raise R43 to maybe 221k. (standard value is 220k tho.)

another thing i noticed, NO triodes in the preamp have a gridstopper on them. that's going to add a lot more RF.

cleans being too warm, raise the slope resistor (R13) to 56k or 68k. 56k will give you the traditional marshall tonestack, BUT marshall's tone stack was after a cathode follower. (low output impedance) and that's why the 56k worked. with a regular triode gain stage, i would suggest raising R13. maybe even 100k. bigger gives you less mids + bass.

you could also add a bright cap on the gain knob, but it won't affect if you play with the gain all the way up. and likewise, it'll make your overdrive a little brighter. to tame the high end, put 1n~3n3 caps across R2, R7, R40, and R42. that'll get rid of annoying highs if you get any of that.


you can't do any of these unless you try them. so good luck, and be safe.

R8 and R34 are the filter resistors, that bring down the voltage of the HT. shorting them will yield higher voltage HT.

R43 is one of the voltage divider.R13 is the slope resistor in the tone stack.

R2, R7, R40, and R42 are the anode load resistors on each triode gain stage.
Call me "Shot".

ShotRod Guitar Works

Custom Hand-wired Amplifiers and Effect Pedals.

Est. 2007


Source to everything I say about Guitars, Pedals, and Amplifiers: I make them.


UG's Best DIY PedalBoard
#17
oops excuse me, i'll correct my suggestions. haha

to get "better" cleans, i would lower that plate resistor (that's acting like a top boost on an AC30) first. lowering R3 to 100k.

then biasing the triodes, i think cathode resistors of around 1k5~1k8 would work. biasing closer to the center will give you a bit more clean headroom as well. however messing with this, will alter the breakup. if you want to play with the breakup characteristics + overall distortion stability, these (i think) are great to fiddle with. well, to an extent. i'd go for 820R~2k7 on these. V2A is biased near cut-off. i think R13 could be more like 2k7 instead of 10k. however, 2203 JCM800s had 10k here. nobody complained about that did they?

then modify the tone stack a little. it's not preceded by a cathode follower, and it has a marshall tone stack. i'd say raise R18 to around 56k~68k. using a 330p cap for C12 might be better too, but that's for your taste. 470p would give you more of the "bite" that marshalls have.

four cascading gain stages, that's a pretty gainy amp. so there are a lot of voltage dividers involved.

try some of those i guess...
Call me "Shot".

ShotRod Guitar Works

Custom Hand-wired Amplifiers and Effect Pedals.

Est. 2007


Source to everything I say about Guitars, Pedals, and Amplifiers: I make them.


UG's Best DIY PedalBoard
#18
Awesome. Definitely got some work to do with it then.
thanks
Guitars
Gibson SG '61 Reissue 'Aretha'
Fender MIM Strat 'Rosy'
Takamine EG 332c 'Betsy'
Epiphone G-400 'Lucy'

Amps
Crate V-18 1x12
Roland Cube 30x


Pedals
Dunlop Original Crybaby
Electro-Harmonix Double Muff
Line 6 Echo Park