I got the Vox board + OT + tube, guess what...I prefer the Valve Jr stock amp!

[BadAssBluesDude]

I'm new here to this forum and if you've seen my previous posts I haven't used and amp in 25 years. I bought a Valve Jr half stack and loved it. I'm a DIY-er, but new to tube amps so before I started my own modding I wanted to do a lot of homework.

 

While I was learning, I bought a Valve Jr head on Ebay with the turretboards.com Vox board, the Heyboer OT, and a new 12ax7. I just got it and don't get me wrong, it sounds great, but I think I prefer the stock Valve Jr. Am I insane? I guess it's just a matter of taste, but the modded amp has no clean headroom at all, and I'm just not digging the tone as much.

 

I've got a 5751 tube on the way to swap out with the 12ax7, and I might even try a 12au7. That might change my opinion.

 

I guess I might turn around and sell the modded amp and then maybe try the BitMo Mod and maybe a new OT in my stock amp.

 

 

I'd love to hear some feedback to see if anyone else has any similar experiences.

 

TC

[cGil]

That Heyboer is a sweet OT with exceptional detail and great dynamic balance. And a turretboard amp is far easier to mod and much more reliable than the stock pcb amp, but I'm not surprised you don't care for the tone out of it. I have my own preferences as well, and that Voxy mod doesn't do it for me. Don't care for the basic Marshally mod, either. But that's the great thing about modding. You can push it in any direction you want!

 

So, swap C1 for a standard .022uF, tweak C3/R9 and C4/R8 as required, and use 100k in both R6 and R7 to restore the original gain curve. If you want the Bitmo tone pot, take R6 and R7 back to 1M. If you want more harmonics, try a 100k 1/2w carbon comp in R4. Want more of a musical sparkle in the tone, try Sozo caps in C1 and C2 (makes Orange Drops sound boring and sterile in comparison). Want less sparkle and a ceiling to icepicky brightness, try those smooth sounding Mallory 150 caps. It's the little things like these that make the tone what you want it to be!

 

Gil...

[AnthemBassMan]

-Have you heard the Fenderish Champ mod from Turretboards? I have one of their boards for my Ver. 1 combo but haven't gotten around to wiring it yet. I was thinking either the stock VJ values or the Champ. Any other ideas? I'm not really interested in high gain. If I want that I'll just throw a pedal in front. I kind of really like the stock tone with the volume at around 11-12 o'clock.

 

L8R,

Matt

[cGil]

I kinda like a blend of the Fender and Marshally mods via a C3/NFB+C4 switch plus a gain switch. That way, I can get pretty much any tone I want, any time I want.

 

http://i166.photobucket.com/albums/u103/cgil155/AbbeyFunk47-Final.jpg

 

Gil...

[Cole]

Hey gil which would you recomend for C1 and C2, mallory, sozo or oarnge drop? My main tone i'm shootin for is a Billy Gibbons/ Jimmy Page/ Angus Young tone. My old V3 Vj has a lot done to it. For the new one this is what i've done so far and yet to do. R1 1meg. C3 stock but on a switch. C4 4.7uF. R6 100k. R7 1meg/100k on a switch. I don't think i'm gonna add a tone control to this one but i might. I plan to change R2 to 10k. R4 to 100k 1/2w carbon comp. C4 to 1uF. R8 to 1.5k. R9 to 680 ohm. C5 to 1000uF. I'm gonna order all the parts soon and was just wonderin which caps i should get for C1 and C2 and if there is a big enough difference in them to put on aswitch. I really like the old school marshall tone. not too hot but just hot enough like right on the edge. Also are 3w metal oxide resistors okay or what kind of resistors and caps should i buy?

[BadAssBluesDude]

Thanks everyone.

 

Gil, you're right, I'm going to keep the modded/eyelet board to modify and sell my stock VJ.

 

I'm new at this so please bear with my questions. My biggest problem with the Vox board is the gain issue. So, currently according to the layout I see on turretboards.com

 

C1 is presently .0022 and I want to switch that with a .022.

 

When you say "tweak C3/R9 and C4/R8 as required" could you go into a bit more detail about what I should be tweaking and how and why etc.?

 

You say "use 100k in both R6 and R7 to restore the original gain curve", according to the layout I'm looking at it says R6 and R7 already are 100k.

 

AnthemBassMan, I think the Fender mod is more what I'm looking for. I'm still learning so who knows where I'll end up. Sewatt.com just go back up today so having never been there before I've still got a lot of reading to do.

 

Gil, thanks also for the tips about the Sozo and Mallorys, that's exactly the type of stuff I need to be learning.

[Steven Lister]

...guess what...I prefer the Valve Jr stock amp!

I'd love to hear some feedback to see if anyone else has any similar experiences.

V3 stock (w/tube upgrade) is hard to beat.

I work on sh*t all day long' date=' so the last thing I want to do when it comes my time to play is to work on something else. Most of the mods I've heard sound okay, different, but not a Marshall, Vox, or Fender. layboomo has/had a cool Vox"y" mod.

 

But the time investment to mod versus the still mostly one dimensional unit setting in front of you at the end of the job just doesn't add up for me. If it's a choice that must be made, then I'll just work some overtime and take my bounty and buy my all-time favorite "holy grail" amp for added tonal dimensions -- instead of the pitfall of the never ending mod search for the holy grail.

 

To each his own -- so I'll take my labor free V3 and multi-modeler POD -- and have time leftover to....

 

Hit every BLUE NOTE baaaby..., I'm going to play on:-"

[cGil]

Cole;

I've gotten to the point where I'd personally rather just use Sozo's, period! Regardless of the style of the amp I was shooting for. They have all the sparkle needed for Fender mods, so I like 'em on Californicated amps as much as I like 'em for Britishized amps. They do require a fair bit of bench time to break in and sound right, but they're well worth it to my ears. I used to switch coupling cap types back in my spaghettimeister Calico amp mod days, just to see how many different amps I could build into one amp, but I've sorta grown outta that.

 

3watt Metal Oxide resistors are great for R12 and R13 as well as the screen grid safety resistor. That's where I use 'em.

 

 

BadAssBluesDude;

Yep, the .0022uF coupling cap in C1 sounds about like a #10 on the sphincter factor scale to me. Swap it back to a .022uF to get the bottom back into your tone. The coupling cap, in combination with the resistor to ground form an RC filter that sets the bottom end rolloff frequency.

 

http://mysite.verizon.net/ackman11/filters/rcfilters.htm

 

 

For C3/R9 and C4/R8 values, try what Cole suggested above. He's on the right track.

 

As to R6/R7. I was thinking they eliminated R6. Guess I was wrong. Still, it's pretty simple to explain. R6 and R7 form a voltage divider, allowing a percentage of the signal to pass to the next stage, while dumping a percentage to ground. If both resistors are equal, you'll get 50% of the signal to pass. If R6 is lower than R7, more signal will pass to the next stage, resulting in higher gain. If R6 is a higher value than R7, less signal will pass, resulting in less gain.

 

Theoretically, a 100k/100k combination is exactly the same as 1M/1M. But this is guitar amp stuff, which means reality sometimes throws theory a curve! In this case, it's the volume pot in parallel with R7. So 'THE' stock gain curve will be achieved by 1M/1M and a 1M volume pot. Still, once you grasp the voltage divider thing, the rest is just a tweak away.

 

http://www.aikenamps.com/VoltageDividerRule.htm

 

Gil...

[mrjones200x]

I found the bitmo trio mod was good in the way that you can have almost the stock sound with the boost pushed in and the tone on 12 oclock and the voicing switch in the middle position and then youve still got all the extra options when you want them. I normally play with the gain boosted and the voice on the crazy setting!

[layboomo]

Yup I wouldn't be so quick to judge the whole mod based on that .0022 uf cap sucking all the life out of the tone! My voxy modded jr is a hybrid like Gil suggested. I'm also a fan of the c-3 lifted tone in valve jr's as well and I use 2 500k pots (volume and gain ala the original marshall drawing from Ken @ Watts)with 2 100K values in R-6 and R-7. There is a good thread on coupling cap values for the voxy mod over at sewatt.com .

[Cole]

how many watts do the other resistors need to be and are electrolytic caps okay? I think i'm gonna go with sozos. About how long do they take to break in and is C1/C2 the only place to use sozos?

[cGil]

The resistors in the preamp (R1 through R9) can be 1watt carbon film. Actually, they only need to be rated for 1/2watt to survive, but the 1watters are more quiet. http://aikenamps.com/ResistorNoise.htm

 

R10 should be a 5watt cement block. R12 should be a 3watt, and R13 and R14 should be at least a 2watt. A 5watter in R14 is common.

 

C1 and C2 are the only places for Sozo's. They're coupling caps and should be rated for at least 400v.

 

C3 and C4 are cathode bypass caps, which will only have a couple volts on 'em, so they can be rated from 16v to 100v(max). Don't go over 100v or the caps will never form properly.

http://www.harpamps.com/micKcaps/Forming-Capacitors.html

 

C5 is also a cathode bypass cap, but it'll have around 10v on it, so a cap rated from 25v to 100v is appropriate.

 

The rest are power supply filter caps and should be rated for at least 50v more than what they'll be required to handle. 450v caps are common here, with the exception of C12, which is a filter cap for the heaters and only needs to be rated for 35v to operate safely.

 

Gil...

[m-theory]

I've gotten to the point where I'd personally rather just use Sozo's, period!

 

I can second that, after replacing the Mallorys in mine with them. Noticeably sweeter, smoother high end. Spendy as hell, but worth it, imo. I did discover the other day that Weber is selling them much cheaper than I paid for mine.

 

R10 should be a 5watt cement block.

 

Or a jumper. It's only there to stablize the power supply, from what I've been told, so if you get quiet power without it, there's no need for it.

 

i'm gonna go with sozos. About how long do they take to break in

 

100 hours, according to Sozo.

[cGil]

Yeah, that 100 hour guesstimate sounds about right. I can hear 'em start to open up by the time they get 50 hours or so, but I prefer to leave the amp fully powered up for a solid week when possible. By then, the Sozo's are totally ready for prime time. This also gives me the chance to see if there are gonna be any premature parts failures or whatever and stomp any remaining gremlins.

 

As far as Sozo's costing a couple bucks more than Orange Drops, IMHO they're definitely worth that extra pocket change. Especially when I look at the nauseatingly obscene prices on some of those high end boutique oil-in-paper caps like they have at Angela Amps or PartsConnexion. Like I want to pay $20 to $40 bucks on a cap that'll most likely take a crap all over the amp after a few hundred hours of use? Not even close!

 

Gil...

[ssgfowler]

I like the Sozos' in my amp a lot, but they're not just for amps. I used them in my SG to replace the crappy stock ceramic tone control caps. The difference really is like night and day. They're a little pricey, but not nearly as much as oil in paper caps.

[Cole]

This is probably a really stupid question but when you leave your amp powered up for an entire week do you mean you just have it on to break in the caps or you have something playing through it?

[cGil]

Nope, not stupid at all. I just turn on the amp (with speaker attached, of course) and walk away. The caps only need voltage applied to 'em, so it can't be in standby mode.

 

Only if I'm breaking in a speaker at the same time does it need to be played. Those can take 100 hours of thrashing to loosen up, usually by FM radio. BTW, I also use old bench tubes for these jobs. I save the good tubes for afterwards.

 

Gil...

[Cole]

Okay thanks! I'm gonna order the stuff probably tomorrow but i'm gonna give all the parts to someone to give me for christmas because noone knows what to get me. I figured that i would put in the stock tubes to break in the caps and save my good ones. What i'm gonna order for my amps is as follows...The *s are what i've already done. i'm gonna order everything else...

......................Head(dirty)................................combo(clean)

R1......................1meg*.......................................1meg*

R2......................10k............................................68k*

R4......................100k 1/2w carbon comp............100k 1/2w carbon comp

R6.......................100k*.......................................100k/remove on switch*

R7......................100k/1meg on switch*..............100k*

R8......................1.5k...........................................1.5k

R9......................820ohm.....................................1.5k

C1..................... .022uf sozo.............................. .o22uf oarnge

C2.................... .022uf sozo............................. .022uf oarnge

C3.....................22uf/remove on switch*............22uf/remove on switch*

C4.....................1uf*...........................................1uf/10uf on switch*

C5.....................1000uf.......................................1000uf

...........................................................................Tweed tone control*

.........................JJ EL84*......................................JJ EL84*

.........................Tung-Sol 12AX7*........................Jan Fillips 5751*

 

 

Do the oarnge caps take time to break in also? And my amps sound amazing as is right now so after christmas im gonna be in hog heaven!!

I just don't see how they can get better but when all i had was a stock V3 stack thats what i thought and i've came a long way so... I'M ADDICTED

[cGil]

Looks like a good parts list to me, although I'd probably opt for an optional 5uF for C4. Even that is actually a little too phat for humbuckers when the amp's cranked, but it does sound really great when clean.

 

Orange Drops sound good from the get go. I haven't noticed much of any change over time. Not so with the Sozo's, which sound brittle and harsh like a new speaker for the first 20 or 30 hours or so. I had to learn to disregard the initial tone from 'em. Glad I did!

 

Gil...

[BadAssBluesDude]

Boy this thread has taken off! Now that sewatt.com is back online I've been studying everything I can, my brain hurts. I've decided to keep the head with the "Vox" eyelet board and new OT. My main priority is reducing the gain. As I've said earlier, I'm looking for a clean but gritty country Tele twangish sound.

 

I've been reading everything I can about the NFB mod, but I just want to make sure that I'm doing it right. Sewatt's search function doesn't seem to be working so I'm probably still missing stuff. Does anyone have "diagram for dummies" showing the NFB mod? I don't read schematics, I'm trying to learn.'

 

Can someone answer me this???... I've been studying the turretboards.com "Fenderish Mod Layout" diagram and it looks to me that this has the NFB mod on it, just without any switch, am I correct?

 

As I've said, I've got a 5751 tube on the way, and I'll probably try a 12au7 as well. Once I get the gain tamed down a bit I'll start experimenting with changing out parts to tweak my sound.

 

Any comments, advice, suggestions would be appreciated.

 

Thanks everyone,

TC

[cGil]

Yep. Turretboard.com's layout is just the NFB resistor hardwired to the cathode (along with R9), and with C3 eliminated as required for NFB. It's definitely better on a switch cuz NFB can sound kinda thin at a lower bedroom practice level.

 

 

 

Here's how to do the C3/NFB switch:

 

Don't connect the "+" end of C3 to the board. Instead, attach a wire to the "+" lead and run that wire to one of the outside lugs of a SPDT "center-off" type of toggle switch. Attach another wire to the solder lug on the the board where C3's "+" lead used to connect, and run that over to the middle lug of the switch. That'll switch C3 in and out of the bias circuit. Finally, attach a 22k or 27k 1W resistor the hot lug of the 8ohm speaker jack, and attach a wire to the other end of that NFB resistor and run it to the remaining outer lug on that switch.

 

That's all it is, but it gives you three different amps to play with: one that's fat and clean down low (C3-in), one that stays tight and rocks at middle to max volumes (C3-out), and one that stays clean up to almost 3pm on the volume (NFB). And turned up is where NFB really shines brightest. Between 3pm and max volume, it's got a tighter slope into power tube distortion that's loads of fun to play with pick attack.

 

Adding to that for a fat & twangy tele, I'd recommend 4.7uF (or 5uF) 25v - 50v caps in both C3 and C4. The stock 1.5k resistor in R8 is fine, but a 750R resistor in R9 is needed for a light touch of grit like you'd get from a cathode follower tone stack amp like a Bassman or Plexi. 1/2 watt resistors will work fine, but 1watt resistors in the preamp will be quieter.

 

For a tighter power tube feel, I'd go with 1000uF/50V for C5, and a 47uF/450v filter cap in C6. For a really tight and punchy response, try 100uF/450v in C6, and 47uF/450v caps for C7, C8, and C9. If you like it feeling loose and sloppy, stay with the stock 22uF caps from C5 to C9.

 

Gil...

[BadAssBluesDude]

Gil, you seriously rock. A few more newbie questions...

 

Am I correct that you suggest only using Sozo cap in C1 & C2? Should I just swap them out for the same value?

 

What brand should I use for the other swaps?

 

There seems to be huge differences in capacitors, but resistors seems to be pretty generic. Am I right? Are, (for example) Radio Shack resistors the same quality sound-wise as any I'd buy online? Is there a brand of resistor that I should look for?

 

You use the term "filter cap". Is that a different kind of capacitor or is that just a reference to what function it is performing in that location?

 

I've read so much this past week, my brain is mush. I seem to remember reading a post that suggested if I tried to put the NFB switch on the back instead of the front, it would cause noise being so close to the OT. Is that correct? Does it matter where I put it?

 

Thanks again everyone.

TC

[cGil]

Yep. Sozo's make for very good, very musical sounding coupling caps with plenty of sparkle and chime. I simply prefer the character of the subtle coloring of Sozo for coupling caps like C1 and C2, as opposed to the totally uncolored Orange Drop, or the heavily colored Mallory, if you want to look at it like that. They're also good for bass and mid caps in tone stacks, but I often choose Orange Drop for those jobs unless I'm going for a totally consistent mustard cap look look for a project. In a tone stack, I prefer a little coloring as possible. For the treble cap in the picofarad range, I'll only use Silver Mica caps. Ceramic caps sound brittle to me.

 

On the other hand, when it comes to filter caps, it's usually a case of they either work or they don't. Not much difference between an amp with cheep Xicon or Nichicon or IC (Illinois) power supply filter caps, versus one with expensive F&T's or monsterously huge Sprague Atoms. But I would certainly expect the better quality caps to last longer. These days I typically use F+T caps in the PS, because they're reliable and look really good. For the low voltage preamp and power tube cathode bypass caps, I prefer the Spragues for their reliability.

 

But electrolytic caps don't filter high frequencies as well as non-polar metal film caps like Sozo, Mallory, and OD, etc. This is one of the reasons for having that big .1uF C11 in parallel with C8. On the pcb, C11 was also due to noise picked up from jumper Jp3. I learned a good lesson from that and now use a cheep green 0.68uF/100v metal film caps in parallel with the cathode bypass caps C3, C4, and C5. It opens up the top end, and can help smooth the typically harsh top end of an el84 or the spikey high end of an Orange Drop coupling cap for example.

 

From what I've learned around here, every little tweak you make, no matter how subtle, really adds up in the final tone. If you hear a Junior with run of the mill parts in a head to head shootout against a Junior with high end parts of the exact same value and a lot of love and TLC put into lead dress, the differences can be pretty dramatic to my ears. But no two ears are the same, not even mine; and as always, your mileage may vary. So don't be afraid to experiment and always follow your ears.

 

Gil...

[cGil]

Forgot to mention...

 

You can also combine cap types on the coupling caps! An Orange Drop and Mallory will have different charge-discharge cycling rates and when in parallel, will pass more tone! And the values simply add up, so a .01uF and .01uF would result in a .02uF combined value; or in your case, your .0022uF and a new .022uF would result in a .0242uF combined value. Ken Fisher figured this out and used this trick on his Trainwrecks. And that guy was one serious master of tone mojo!

 

Gil...

[BadAssBluesDude]

Okay, all this info/help has taken my dilemma in a new direction. As I've said I've got the turretboards.com Vox board in my VJ, rather than swapping out all these parts as suggested, wouldn't I probably be better off just buying a new blank turret board and loading it with the parts I want?

 

As I said in my first post, I haven't owned an amp in 25 years, and I must confess, I've never played through either a Fender nor a Vox. Is the Fender board closer to the clean, gritty, redneck, Tele twang that I'm looking for, or should I just start from scratch using a parts list based on the information that you all have so graciously shared with me in this thread?

 

 

Thanks everyone,

TC