pharpo
384 posts
Oct 27, 2010
5:01 PM
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I just picked up a Crate V18-1-12. I thought it sounded better than the fender Blues Jr. that was next to it. Are there any recommended tube swaps to make it even more "HARP friendly"
thanks !
Paul
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Music is your own experience, your own thoughts, your wisdom. If you don't live it, it won't come out of your horn. They teach you there's a boundary line to music. But, man, there's no boundary line to art. - Charlie Parker
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roberth5
20 posts
Oct 27, 2010
9:10 PM
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Hi Paul,
Why don't you call, or email the guys at Tube Depot.
I found them really helpful.
http://www.tubedepot.com/?gclid=CJ_9tvfX9KQCFQjPbgodxWGbhw
Rob
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pharpo
385 posts
Oct 28, 2010
3:52 AM
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Thanks roberth5 !
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Music is your own experience, your own thoughts, your wisdom. If you don't live it, it won't come out of your horn. They teach you there's a boundary line to music. But, man, there's no boundary line to art. - Charlie Parker
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KingoBad
466 posts
Oct 28, 2010
5:42 AM
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Please let us know how it worked for you!
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bacon-fat
24 posts
Oct 28, 2010
8:57 AM
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With 3 12ax7 preamp tubes in that amp you could mess around with them; try swapping the first one with a lower gain 12ay7 and see how you like it
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toddlgreene
1988 posts
Oct 28, 2010
9:07 AM
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Also, isn't that a double EL84 amp? if so, and it has Sovtek or ElectroHarmonix or other cheaper Russian-made tubes, they have a harsh-sounding distortion. The JJ's are considerably warmer sounding and greyplate 6QB5 tubes are nice as well. I'd like to hear it!
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Todd L. Greene, Codger-in-training
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pharpo
386 posts
Oct 28, 2010
1:53 PM
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@todd -thanks you are the second person to suggest JJ's
@ bacon-fat According to the schematic the are 4 12ax7's . One prior to the overdrive/gain (v1A) and then three more after that - v1B / v2A / and v2B...I'm assuming you mean the V1A tube ? AND what about a 5751 ?
Now I am a HAM and familar with tube stuff.....but after I change thenm to I need to get the Bias reset ?
Thanks guys !
Paul
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Music is your own experience, your own thoughts, your wisdom. If you don't live it, it won't come out of your horn. They teach you there's a boundary line to music. But, man, there's no boundary line to art. - Charlie Parker
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Greg Heumann
831 posts
Oct 28, 2010
8:55 PM
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If you have 3 or 4 12AX7's you're gonna have a lot of gain and hair-trigger feedback. Swapping in a single 12AY isn't likely to get you far enough. I would try a couple of 12AU7's in any position but the first preamp position. If that is too far, take one out and go back to something more. If it isn't enough, lower the first preamp tube a little, like to a 5751 or a 12AT7.
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/Greg
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JohnnieHarp
70 posts
Oct 28, 2010
10:01 PM
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Hi Greg
Kudos to you for taking the time to pass on all the great information that you share with all of us ... much appreciated!
Johnnie
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bacon-fat
25 posts
Oct 29, 2010
5:38 AM
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V1A and V1B are one entity; same with V2A and V2B. Separate items in the circuit, yes, but both in one bottle.
No need to rebias when replacing preamp tubes.
Hamfests are good sources for good tubes, military, nos and used.
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Joe_L
756 posts
Oct 29, 2010
9:32 AM
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Paul - I think someone on the Weber board modded a V18 for harp and got it sounding pretty good. I can't remember what they did, but you might want to check over there.
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pharpo
391 posts
Oct 30, 2010
5:57 AM
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Joe...I looked and did a search but could not locate it. There are a bunch of intensive mods out there , but I don't think i need to go THAT far.
Bacon Fat - Thanks !
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Music is your own experience, your own thoughts, your wisdom. If you don't live it, it won't come out of your horn. They teach you there's a boundary line to music. But, man, there's no boundary line to art. - Charlie Parker
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tbirdflier
2 posts
Oct 30, 2010
8:35 AM
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One other though would be to check the amp's output transformer, you may want to eventually swap out the original one for one with more "horsepower".
I did that to a Blues Jr. I use to own and it helped give the amp better tone and more balls.
As far as 12AX7 tubes go, I like the Tung-Sol brand myself.
12AY7's and 12AU7's can mellow out the amp but usually remove a bit of the overall output factor, which may or may not be an issue for the type of playing you are doing.
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joshnat
76 posts
Oct 30, 2010
5:37 PM
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@Greg: can you explain a bit why he should swap the second or third preamp tubes but not the first? I'm dealing with a similar layout in an Egnater head, and it's not bad with a 12AY7 in the first preamp position, but it hadn't occurred to me to leave that alone and experiment with the last two preamp tubes instead. Thanks!
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5F6H
349 posts
Oct 30, 2010
6:24 PM
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Any of the 12A#7 series tubes (inc. 5751) will work in a 12AX7 socket, there's no right or wrong, whatever works for you is right. But in some amps a tube is split between 2 channels & they can tolerate relatively extreme tube subs, if all the tubes and their triodes are in series (as are V1 & V2 in this amp) then you get a much bigger drop in gain...with 3 tube positions, there is an awful lot of variations to work through (180 odd...).
Generally, replacing the preamp tube that feeds the power tubes can have the more subtle effect, as it only drops one stage's gain, as opposed to dropping gain in 2, series stages.
What does all this mean? Eff all really, grab a 12AY7, a 12AU7, a 5751, a 12DW7 & A 12AT7 and swap them about until you get something to work with.
Really the V18 could do with some circuit mods too, but the build construction makes them a PITA...so tube subs would seem the obvious route..
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joshnat
77 posts
Oct 31, 2010
1:23 PM
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The reason I'm asking about V1 is that i read somewhere else the other day that tubing V1 down causes it to struggle with the current developed by a hot mic element. I think it was the harp listserve. If that's true, it makes sense to tube down V2 and V3 to get a handle on the gain of the amp, and leave V1 alone. However, if one of those tubes is the PI, would tubing it down have positive/negative/any effect? I suppose this all has to do with the circuit design of the amp: the only universal is that there are no universals!
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Last Edited by on Oct 31, 2010 1:26 PM
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5F6H
350 posts
Oct 31, 2010
2:20 PM
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The opposite is usually true, that for a very hot element, tubing down the input triode handles the voltage better...of course, in the case of the Crate, changing V1 tubes down 2 stages (V1 a & V1b), unless you use a 12DW7, which has a high gain and a low gain side...can't say for sure which is wher in the Crate without seeing the pin numbers.
Tubing down the PI only drops gain at one triode (effectively) rather than 2 triodes, as with V1 & V2.
There are so many variables, mic, tube in question, how you as a player sound, how you play & what you are looking for...it really is a case of trying all the (180 odd) options.
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Greg Heumann
836 posts
Oct 31, 2010
10:28 PM
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@Joshnat re: @Greg: can you explain a bit why he should swap the second or third preamp tubes but not the first?
I can't give you a theoretical answer. I learned this from Sonny Jr - this is how he sets his amps up. I experimented quite a bit as well with other combinations but found this seems to work well for most people. YMMV
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/Greg
Last Edited by on Oct 31, 2010 10:28 PM
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5F6H
351 posts
Nov 01, 2010
2:22 AM
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"I can't give you a theoretical answer. I learned this from Sonny Jr - this is how he sets his amps up." The way Sonny's amps are voiced, Greg has a point...but from amp to amp results change, e.g. an RI bassman, or a Clarke will sound fine with a 12AY in V1. A stock Victoria 45410, Kendrick 2410, stock Weber kit 5F6A, Blues Deville, Laney LC 15 for example, then I'm more likely to run a 12AX7 in V1 & move the 12AY/other low mu tube somewhere else.
Whilst dropping the mu in V1 can make it easier for an amp to handle a big signal, it does also tend to give the biggest change in frequency response, lower mu means less bass (& less harsh high end), so if your amp is a bit "woofy" with a 12AX7 in V1, a lower mu tube can be fine, if your amp sounds OK to start with (12AX7in V1) then it can just go a bit thin/strident with a lower mu tube. Subbing V3, or even a lower mu tube in V2 as well, can make the amp calmer/looser, but typically with a less drastic effect on the voicing/frequency reponse.
As the Crate has 2 series triodes on V1 & V2, V3 might be the place to start...but it has a lot of gain stages, even compared to a Deville...so you'll have to spend a bit of time on it.
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joshnat
78 posts
Nov 01, 2010
5:59 AM
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@Greg and @5F6H, thanks for the answers. I'm actually trying retube an Egnater Rebel 20 head, with which I had been unsatisified after putting a 12AY7 in V1. Original was 12AX7 in V1 and the gain was unbearable. I put the 12AX7 back in V1 and put a 12AU7 in V2 (based on Greg's earlier recommendation for the Crate), and it really smoothed things out. What's interesting is that Egnater recommends running the master volume at maximum and adjusting the Gain knob for distortion. This generates most of the distortion out of the power tubes, rather than the preamp tubes. What a difference when you reverse the knobs (i.e., gain up, master vol down)! The preamp distortion has nowhere near the clarity or smoothness of the poweramp distortion. I knew this in theory, but on this amp you can really hear it. I was going to look for some NOS preamp tubes, but now I think I'll find some NOS 6V6's instead and see if that improves things even further.
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pharpo
578 posts
Jun 01, 2011
4:22 PM
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Well it's been a while since I threw this out there...I thought I would report back to everyone that tried to help. After figuring out how to get to the tubes..(they were not facing the back when the back panel was removed)....I replaced to Sovtek tubes with a matched set of JJ's (NOS). (thanks Todd)
I only had 2 12AY7's (NOS)so after experimenting a bit I put one in the first position and one in the third position.
Pleased to say the amp now has a "mellow grit" that it did not have before. BUT I think that it has more to give me. Going for a 5751 next. I am very happy that I did this....It does sound so much better.
Much thanks to 5F6H / Greg / Todd and all you guys for the help.
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Procrastinator Emeritus
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pharpo
580 posts
Jun 03, 2011
12:15 PM
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OK......Now what about a speaker recommendaton ? Weber ? Jensen ?....it has what i can see....a no name "crate" speaker.....
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Procrastinator Emeritus
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pharpo
639 posts
Jan 14, 2012
4:02 PM
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Hey guys...wanted to update you....As stated above I switched out the Sovtek power tubes with JJ's. I then played around with different combinations in the preamp stage with 12 ax7's and 12 ay7's. My final combination that I believe sounds the best....5751 in the first pre amp position and then 12 ay7's in the next 2. With a hot CM element I can now almost MAX the volume without problems. I can cut through all the "guitar gods) LOL.... Seriously... A great guitar player here in Syracuse has been my biggest supporter...always teaching...coaching...and supporting.
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Procrastinator Emeritus
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