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dmock66

VJ Head - after Vox mod and Hammond 125DSE - too hot

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I've had my Valve Jr upgraded to a Vox mod (using the Turretboards specs) as well as a Hammond 123DSE OT put in. Ever since, my amp breaks up BIG TIME (and not the nice saturation) at around 9:00 on the volume knob where it used to start breaking up (light natural breakup) around 11:30 with humbuckers or 1:30 with singles. I did some testing last night and found that if I put an EQ in front of the amp and pull the level WAAAAY back I get more of the expected results in terms of breakup, but the amp loses a lot of it's alive qualities.

 

Any ideas of what I may have done wrong or what needs to be reviewed/changed to get it so that I'm not at full overdrive at 9:00 on the volume dial? Do some resistors need to be modified? Is it that there input needs to be adjusted?

 

I really liked the Valve Jr stock but after reading all the posts about how much better they sound upgraded, especially with a new OT, and hearing the YouTube and audio clips, I took the plunge. Sadly, I've hardly turned it on since the changes have been done and would like to get this little gem back in my playing rotation.

 

I appreciate any assistance you might be able to provide.

 

David

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I think I can help you get there david...did you use the vox values exactly? List what you did and what kind of tone your after . I'll give you my $.02 on how to get where you want to go.

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I think I can help you get there david...did you use the vox values exactly? List what you did and what kind of tone your after . I'll give you my $.02 on how to get where you want to go.

 

I didn't do the mods - my friend did them for me. However, he did the exact values of the Turret Vox mod and swapped out the stock OT for the Hammond. That's it.

 

To be honest - I was looking for similar tone to the YouTube videos you shot with your Vox Valve Jr. That's an awesome sound!!!

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I think I can help you get there david...did you use the vox values exactly? List what you did and what kind of tone your after . I'll give you my $.02 on how to get where you want to go.

 

... and THANK YOU for your help!!! ](*,)

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OK first of all 9 is early for breakup on the voxy modded amp with stock values. ...I'm wondering if you have a resistor value wrong ..or if you have r-6 jumped out? Try 470k in r-6 and r-7 instead of the 100k values and remove c-3 from the circuit and see what you think. I also think the .0022uf in c-1 removes too much low end IMO,but it's also part of what gives that voxy vibe. If you go with a different value in c-1 you will probably want to adjust the c-3 and c-4 values to compensate. There is a good thread on sewatt about tweaking the c-1 value....you'll have to poke around a bit to find it...but it's there.

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Check the circuit as others have advised; it could be anything in there, really. R6 and R7 control the output gain so yeah; but they're pretty much a fixed volume knob (a kind of multiplier on volume really, if I'm understanding right).

 

I control my breakup with a Bitmo Trio but it'll affect your tone if you add one, you may not like that (so will new tubes though...). There's ways to mess with that thing that get me some nice volume with a good, warm, clean sound, like playing an acoustic really. That amp's capable of so many sounds just by tweaking little parts of the circuit; you'll fix the breakup problem if you work at it enough.

 

One thought, I've got a #35 EL84 from Eurotubes, it breaks up around 10:00 easy. Used to take more pushing to get that sound. Of course you modded your circuit and got that result! If there's nothing in the circuit itself you think you want to change, you could always try playing with a 12AL7 (I believe these are lower gain than 12AX7) or a lower gain tested EL84 from Eurotubes. Maybe scale back the volume on your guitar a bit first though, mess with tone knob too, cheaper than buying new tubes at $10 a pop or so.

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Awesome - thank you for the advice. I'll pass this on to my friend and let you know how it goes. I appreciate your help!

 

I also had a gain pot(500k) instead of r-7 in my amp done like the old style marshall schematic on turretboards.com with a 28k resistor to ground on one side. A preamp tube like a 12at7 or a 5751 might be worth a try too.

 

The other thing I wanted to point out is that I use the volume and tone controls on my guitar quite a bit with the valve jr amps to dial in the tones. If you keep your guitars dimed all the time I find the amps break up too soon for my tastes.

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I'll definitely have all these things checked. I'll also keep in mind the use of the volume/tone knobs to get the tones. I do tend to run my tone wide open most of the time, but I do roll off the volume - so I'll be sure to experiment with that as well.

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I'll also keep in mind the Bitmo stuff as well. I do actually have a 12at7 tube in the preamp right now so I've already tried to tame things down some in that way. It's still at full breakup.

 

My buddy emailed me and said that R-6 may be jumped out. He's going to look at that first.

 

The pot in place of R-7 sounds interesting as well. We're going to start with reviewing R-6 to see if it's jumped and go from there.

 

Thanks again for all the assistance. I really appreciate it. I know there is a lot of tone in this little amp and I'm grateful for all your help to let it out!

 

David

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My buddy changed out R-6 and R-7 with 470k and that did the trick. I've not had a chance to put it in the mix with my band yet (I'll do that tomorrow morning at church) but I plugged my Strat in and didn't start getting breakup until around 11:00 and then it was the desirable, smooth breakup. The tone is AWESOME!

 

Layboomo - thank you SO much for your help in trouble shooting this. I very much appreciate your help and expertise!

 

Bluefoxicy - thank you also for your input as well. I may try some different tubes. I do have a 12at7 in the VJ right now. Now that the mods are where I want them I may see if a 12ax7 gets me better tone. But - I agree with you, the tube changes can be very impactful.

 

David

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My buddy changed out R-6 and R-7 with 470k and that did the trick. I've not had a chance to put it in the mix with my band yet (I'll do that tomorrow morning at church) but I plugged my Strat in and didn't start getting breakup until around 11:00 and then it was the desirable' date=' smooth breakup. The tone is AWESOME!

 

Layboomo - thank you SO much for your help in trouble shooting this. I very much appreciate your help and expertise!

 

Bluefoxicy - thank you also for your input as well. I may try some different tubes. I do have a 12at7 in the VJ right now. Now that the mods are where I want them I may see if a 12ax7 gets me better tone. But - I agree with you, the tube changes can be very impactful.

 

David[/quote']

 

Glad you got it where you want it David....now go tear it up with that tone machine!

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Just a question' date=' Layboomo, what value cap did you use for C1?[/quote']

 

Well I originally used the .0022uf voxy value...but I added another cap to bring it up to around .0047 ish If I remember right. I found that to be the sweetspot with c-3 and c-4 at the stock 22uf values and the rest of the voxy mods. I also have a c-3 lift switch on that particular amp. It really covers alot of ground that way. If you look on sewatt voxy threads some of the other guys upped the c-1 values too. I don't remember the exact values they used.....ask datamonkey....I remember he did it and liked it alot.

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Thanks, I was just curious because the original VOX only used a .0022 on the bright channel and used a .47 on the normal channel if I remember right. Maybe it was .047 hard to say with my brain cloud and all.LOL

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Thanks' date=' I was just curious because the original VOX only used a .0022 on the bright channel and used a .47 on the normal channel if I remember right. Maybe it was .047 hard to say with my brain cloud and all.LOL[/quote']

 

You know what....I just pulled up a gut shot of my voxy build and it sure looks like I put an orange drop on a switch for c-1 and I'll bet it was a .047 because I have a bunch of those in my parts bin. I did alot of experementing on that amp and I'll have to open it up to be sure. That was my first scratch build turretboard valve jr....and I'm a little foggy myself on exactly what I did(it was a while ago)....but I do remember going larger on c-1 and getting a smokin' Brian May tone with a Dano lipsticktube guitar.

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Well I just checked the schematic for VOX AC30 and on the normal channel they use a .047 cap and when I heard your clip on you tube it made me remember jamming with a guy who had one and what an incredibly cool sound came out of that amp.

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I played the Voxy VJ this morning at church with my worship band. Both the other guitar player and bass player commented on how good my tone was with the VJ this morning. We had played a retreat weekend and I used my primary amp (Traynor YCV40WR). This morning, in a more volume controlled environment, I busted out the VJ and the first service with the Voxy mod was a smashing success!!! Thank you for your assistance in getting this amp back in the game!

 

... now to get in a 100 hours and get the caps burned in so the tone gets even sweeter!!!

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I played the Voxy VJ this morning at church with my worship band. Both the other guitar player and bass player commented on how good my tone was with the VJ this morning. We had played a retreat weekend and I used my primary amp (Traynor YCV40WR). This morning' date=' in a more volume controlled environment, I busted out the VJ and the first service with the Voxy mod was a smashing success!!! Thank you for your assistance in getting this amp back in the game!

 

... now to get in a 100 hours and get the caps burned in so the tone gets even sweeter!!![/quote']

 

David I love hearing about success stories like yours....you went from kinda unhappy with the tone...to everybody saying "great tone dude" and all it took was a little effort and a few $ worth of parts....Gotta love it! Congrats!

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I actually liked the tone out of the box. Having heard the tone you get from yours on your YouTube videos I knew it was just a matter of getting to the root of the problem. I am very appreciative of your assistance in trouble shooting my issue. My friend likes working on guitar amps. After working on my Galaxie 10 and Valve Junior he's used his knowledge of circuits to design and build a few amps by himself - two for his son and one for another guy at our church. Very cool. Your suggestions were spot on. I'm not thinking about the .047 in C-1 as well. I know how good it sounds now. If the .047 in C-1 make it sound even more Vox AC-30 like - I'm all for it!

 

Really - thank you. You put a lot into this forum and it's because of your free sharing of your knowledge and experience that people like me get to benefit with amazing tone!!! I like this forum a lot because of the openness and willingness of everyone here to share what they know so that everyone wins. You've certainly helped me at several points along my Valve Junior journey and I'm grateful! I don't really understand all the technical talk... really not at all. But it does show me what a little bit of modding can do to your tone, and that inspires me!

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I actually liked the tone out of the box. Having heard the tone you get from yours on your YouTube videos I knew it was just a matter of getting to the root of the problem. I am very appreciative of your assistance in trouble shooting my issue. My friend likes working on guitar amps. After working on my Galaxie 10 and Valve Junior he's used his knowledge of circuits to design and build a few amps by himself - two for his son and one for another guy at our church. Very cool. Your suggestions were spot on. I'm not thinking about the .047 in C-1 as well. I know how good it sounds now. If the .047 in C-1 make it sound even more Vox AC-30 like - I'm all for it!

 

Really - thank you. You put a lot into this forum and it's because of your free sharing of your knowledge and experience that people like me get to benefit with amazing tone!!! I like this forum a lot because of the openness and willingness of everyone here to share what they know so that everyone wins. You've certainly helped me at several points along my Valve Junior journey and I'm grateful! I don't really understand all the technical talk... really not at all. But it does show me what a little bit of modding can do to your tone' date=' and that inspires me![/quote']

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I actually liked the tone out of the box. Having heard the tone you get from yours on your YouTube videos I knew it was just a matter of getting to the root of the problem. I am very appreciative of your assistance in trouble shooting my issue. My friend likes working on guitar amps. After working on my Galaxie 10 and Valve Junior he's used his knowledge of circuits to design and build a few amps by himself - two for his son and one for another guy at our church. Very cool. Your suggestions were spot on. I'm not thinking about the .047 in C-1 as well. I know how good it sounds now. If the .047 in C-1 make it sound even more Vox AC-30 like - I'm all for it!

 

Really - thank you. You put a lot into this forum and it's because of your free sharing of your knowledge and experience that people like me get to benefit with amazing tone!!! I like this forum a lot because of the openness and willingness of everyone here to share what they know so that everyone wins. You've certainly helped me at several points along my Valve Junior journey and I'm grateful! I don't really understand all the technical talk... really not at all. But it does show me what a little bit of modding can do to your tone' date=' and that inspires me![/quote']

 

Thats what it's all about my friend sharing knowledge and great tone....and just to keep it real... I only passed on what I learned from others as well. Glad you are diggin' the mods. It's alot of fun...and when you have an amp that's custom it's just a little cooler!

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Thats what it's all about my friend sharing knowledge and great tone....and just to keep it real... I only passed on what I learned from others as well. Glad you are diggin' the mods. It's alot of fun...and when you have an amp that's custom it's just a little cooler!

 

I agree. Having a custom amp that sounds great is a cool deal, no doubt about it. And, I'm already getting the "you're getting that much tone out of that little amp" from people in my congregation. I luv it!

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I've been playing the Voxy Valve Jr for several weeks now and my bass player is still making comments about how sweet my tone is! That's a true testament to this little amp as he's particular about sound. But, I've gotta agree with him - it just sounds awesome!

 

At the same time as I re-introduced the modified Valve Jr I also brought back my Japanese Strat with a Seymour Duncan Little 59 in the bridge. The combination of that guitar and the VJ is a match made in heaven!

 

Thanks again for all the assistance in getting my VJ back in play. It's my "go to" amp now!

 

David

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