BadAssBluesDude Posted November 26, 2008 Share Posted November 26, 2008 I've been a professional musician all my life. In the "big hair" 80's I used rack gear and then in '92 I got a cruise ship gig and started using a Roland VG (digital modeling) system, so even though I've made my living playing guitar, I haven't owned an amp or a pedal in over 25 years. Now that I'm back on dry land I'm getting into the Valve Jr thing in a big way. Normally I'm a DIY-er, but I build guitars, teach school, gig, and have a 2 year old so I don't have time to do a lot of modding myself, plus electronics are my weakness. I plan to get my feet wet with a "buildyourownclone" pedal so I can't set the house on fire. I bought a stock Valve Jr., (love it) and was about the buy the parts to do the turretboard.com "Vox mod" + OT + new tubes, when I found one already done on Ebay for less than the price of the parts! (currently being shipped) Here's my questions...some of which this forum has already answered, I'm just checking my facts... I'm playing "Outlaw/RedDirt" country music so I want more clean headroom, my plan is to change out the 12ax7 with a 12au7 or a 5751. Will this clean up my tone without sacrificing volume? Do I just want a JJ gold tube? How are GooveTubes tubes? What are the best and are they worth the extra $$$? Next, I haven't found anyone who has done a mod involving a footswitch. I'd love to have a "lead switch", or if using (for example) the Bitmo mods, I'd love to be able to switch things with my feet instead of at the amp. Any ideas? This might be a really stupid question, but remember I haven't used a real amp in 25 years, is there such a thing as an A/B box where you can use two heads that share the same cabinet? Like I said, I'll be playing country, is the stock 1-12 speaker okay or should I think about upgrading? Although I have a ton more questions, I'll make this my last for now, I've seen a lot of people flipping their chassis over so the tubes are on top. To me, this seems like it will help ventilation, is this something I'll want to do? Thanks everyone and p.s. I've love to see any and all pics of mods, upgrades, and "re-designs". TC Link to comment Share on other sites More sharing options...
cGil Posted November 27, 2008 Share Posted November 27, 2008 Radial's Tonebone series pedals have 'Ampbone' and Cabbone' models that do amp head and cab switching. But each one cost as much, if not more, than the VJr head and cab combined! The far cheeper option is to just get a cab for each amp and an ABY pedal to do the switching! There is a gain-boost mod that can be accomplished by footswitch. The original mod came from Blackheart, but it's easily adapted to the VJr. It simply requires on start with 100k in R6 and 1M in R7, with a 100K switched in parallel with R7. This mod does not work well with the Bitmo tone, but works just fine with the standard Tweed tone pot. For the most clean headroom possible, you'll need to disconnect C3 and add Negative Feedback. Preferably on a 3-wa7y switch so you can access all three options. This is commonly referred to as the C3/NFB mod. A 5751 (my fav), or a 12AT7 will still give a good bit of gain. The 12AT7 sounds like a slightly stiffer 12AX7 to me, while the 5751 sounds brighter, with a smoother distortion character that I happen to really like a lot. A 12AU7 or 12AY7 will offer a lower gain factor than either the 12AT7 or 5751. Gil... Link to comment Share on other sites More sharing options...
BadAssBluesDude Posted November 27, 2008 Author Share Posted November 27, 2008 Thanks for your response. In my long-winded post I forgot to mention the most important thing. When talking about electronics, please talk to me like you would a 4-year-old, because I know virtually nothing about it. I can solder, and if I see something done, or have very detailed (for dummies) instructions, I can do basic work, but when it comes to terminology, I'm a dullard. Redial. I knew I had seen that before. Although cost is always and issue, it's more of a space issue. I have a very small car and I don't think I can fit another speaker cabinet in there. I read about the C3/NFB mod option but I have no idea what that means. I'm assuming that disconnect C3 means taking out a capacitor, but I have no clue what "add Negative Feedback" is. Is there a tutorial you could point me to? I keep seeing references to sewatt.com but their site is down. I've also read that the C3/NFB mod will reduce output. I'm wanting to keep as much output as possible, I'm just trying to tame my gain. If for no other reason than the learning experience, I'm going to buy all the tubes and experiment with swapping them out. I've read previously that I won't need to worry about rebiasing, is this correct? I think I follow what you're saying with the footswitch idea. Thanks TC Link to comment Share on other sites More sharing options...
mcrracer Posted November 27, 2008 Share Posted November 27, 2008 As A person with over 35 years training and esperience in tube amps, it scares the hell out of me everytime I see posts like this. While I applaud your desire to want to improve your amp, the fact that you really do not know what you are doing concerns me. You don't wake up one day and decide you want to do heart surgery on yourself. There are lethal voltages and currents present inside any tube amp and you really should at least attempt to acquire basic knowledge on tube amps, safety and theory of operation. If you don't care to do that then you really should take your amp to someone who knows what they are doing. It is smart to try building pedals first, only about 9 to 18 volts there, but attempting to learn on over 300 plus volts well... I do plenty of amp repair where a newby was in them first and I have to straighten out the mess.And it costs them significantly more for me to fix their mess and then do the mods they wanted in the first place. Not trying to bust your chops, just want you to be around with us for a long,long time. Happy Thanksgiving to you and yours. Link to comment Share on other sites More sharing options...
BadAssBluesDude Posted November 27, 2008 Author Share Posted November 27, 2008 No bubble burst, I appreciate your concerns, and I do not at all approach this undertaking lightly. I know all the voltages involved, I know how to discharge a capacitor, and especially with something like this, I'd never undertake a mod without being 100% I'm following proper procedure. That's why I ask so many questions. I'm just the type of person who has to experiment and learn. I maybe understated my knowledge of electronics a bit, but I'd rather have someone give me too much information. As far as the C3/NFB mod goes, I took apart my stock Valve Jr. and I have Version 3, which does not seem to have the C3 slot where I've seen it pictured on earlier circuit boards. Of course any info I can get from this forum, I'd appreciate, but the more I study it looks like sewatt.com is the source for most of my answers, I might just have to wait for their site to come back up. TC Link to comment Share on other sites More sharing options...
pharmrock Posted November 27, 2008 Share Posted November 27, 2008 TC... I bought my VJ back in March and, like you, I was relatively new to electronics. I changed pickups in my guitar, and added a neck-on switch, but that was about the extent of my soldering skills. What I highly recommend is you read like crazy before you begin. Also...I have found working on the PCB adds an extra dimension of difficulty...if you are getting a turret board, it should be much easier. I found this document to be incredibly useful in preparation of working on my amp: www.s2amps.com/docs/vj_kit_inst.pdf My advice (remember...I'm still relatively new at this) is to take it slow. Make a couple of the simple mods first and get comfortable working with the parts. As you gain experience and confidence, you will be able to tackle the more "difficult" mods. I started with the R1/R2 changes, and have now ended up with a completely Marshallized VJ with a tweed tone, a gain control, NFB/C3 mod, and a VVR (variable voltage regulator). Standby switch and Hammond 125ESE output tranny as well. Additionally, I tried a conjunctive filter but ended up removing it. Again...my best advice is to read, read and read some more. Start out simple and go from there. THERE IS DANGER!!! But follow the instructions and always use the "one hand in pocket" approach when measuring voltages. Once sewatt is back up and running, review all of the materials for making mods. The guys on that forum are incredible and have years of experience. Anyways...good luck! I really enjoyed working on my valve junior. I followed all of the instructions exactly and the only problem I had was when I installed NFB and ended up motor-boating...just had to swap the OT primaries and was good to go. I now have a tweed deluxe that I will start tweaking soon. Link to comment Share on other sites More sharing options...
TWANG Posted November 27, 2008 Share Posted November 27, 2008 I didn't have any electroncis experience either. And the general concensus, even after I had modded amps, by some here and elsewhere, was that I wasn't worthy. At least that's the impression I got. So I'm not gonna mess around.. I've been sticking my nose into everything electronic for years.. junked stuff.. grabbing parts out.. tvs stereos radios phones and more and in that time I've never gotten a shock that I can recall. Not one. Furthermore, the instructions you get here and at sewatt take that into account, and explain it well. You can do it, and it's fun. And it pays off. In all the time I've worked on several epis, the worst that's happened was a fried resistor.. ok, it glowed. *S* but that was fun, too, frankly. read and understand the precautions and what do you find out..? there are just a couple of things where danger is present in the vj. And habit will cure it's risk. my amps work. I quit even asking for advice since people seemed to think I should have learned or memorized every detail.. this despite the fact that I had no experience, picked it up piecemeal, smoked a lot of.. er.. check that!, and didn't do this daily, as if it were some course I was taking and had a real instructor. Now, I don't need all that anyway, so I'm fine with it. There are people you're going to run into who want to help and those who don't even want you to try, and those who will judge you along the way, sometimes quite unreasonably. Welcome to life. But if you want to, you can. And you should. And you wont die unless you ignore the information, of which there is plenty. Don't expect to become an engineer after doing some mods.. but do take stock of the fact that there are more than one company out there selling parts for do it yourself modders.. people with no experience at all, who simply follow instructions. Nobody should tell you you shouldn't or can't. It's NOT rocket science and they aren't all genius's. First find out which things people are really happy with.. then recognize the limitations of a two tube amp.. big clean headroom isn't on the menu.. for example. but nice cleans certainly are.. great home practice or recording amp for clean or dirty. most of the knobs and switches only do incremental changes... the good stuff is primarily replacing rather low end parts with good ones.. getting good voltage through the circuit. the fabled sweet spot! the less knobs and switches the better, really, for most people. You'll see, fairly often, guys who just have the three stock things.. input volume power. and that will do! tweed tone control is probably a second fave. NFB is a nice choice. I like a gain control, but not a master volume which I found pretty much useless. the loop d jr is handy, but not the same as a typical efx loop. read the faq.. take your time and ask questions up front about the usefulness of the mods.. then layout your choices for critique.. then read again on procedure.. taking care to get the good parts, watching your budget for shipping and parts cost.. and you can wind up with a really special VJ you'll enjoy and find good use for for years. Take everybodys opinion with a grain of salt.. and enjoy yourself.. have fun. TWANG Link to comment Share on other sites More sharing options...
Eracer_Team Posted November 27, 2008 Share Posted November 27, 2008 I can only add one thing to Twang’s writings… TAKE YOUR TIME…. If you modify 5 things at one time you’ll probably be asking why it doesn’t work; and we’ll probably smack you for doing 5 things at once. And by doing so you won’t know which of the changes did the most to change the tone the way you like it. Link to comment Share on other sites More sharing options...
m-theory Posted November 27, 2008 Share Posted November 27, 2008 My advice to add would be to refrain from drilling new chassis holes until you're absolutely certainly that the mods you've done (ala switches & knobs) are what you'll actually make use of enough to make it worth carving up the face. I would add that you could consider installing rarely used switches and knobs on the back of the chassis, rather than the front. There's something about that single knob, single switch, single jack face that just seems so elegant and "perfect" to me. Link to comment Share on other sites More sharing options...
cGil Posted November 28, 2008 Share Posted November 28, 2008 That's why I recommend, and use, the C3/NFB switch on every amp I've built. If I had to have a toggle on the panel (aside from the usual power and standby), that'll be the one. A lot of other options can be accomplished by very stealthy looking push-pull pots on front, as well as footswitch jacks on the back. Gil... Link to comment Share on other sites More sharing options...
Just Strum Posted November 28, 2008 Share Posted November 28, 2008 I have to agree with all the advice here. The big thing that is said, is READ!!! You obviously are well aware of that, so I will end any further recommendation with the exception: I purchased my Valve Jr already modded from this guy and whether you contact him or read his site, you will be the better for it. He also offers links to some interesting sites. My doctor http://duhvoodooman.com/VJr/VJr_mods.htm http://duhvoodooman.com/ http://www.ehow.com/how_16749_discharge-capacitor.html My VJr Link to comment Share on other sites More sharing options...
cGil Posted November 29, 2008 Share Posted November 29, 2008 It should be noted that the amps in the S2 and VoodooMan docs reference the Version 1 VJr. Don't do the v1 heater mods on your v2 or v3 amp! Gil... Link to comment Share on other sites More sharing options...
BadAssBluesDude Posted November 30, 2008 Author Share Posted November 30, 2008 Thanks everyone. I kinda have OCD so when I sink my teeth into something I become obsessed and read and study everything I can about it. TC Link to comment Share on other sites More sharing options...
cGil Posted November 30, 2008 Share Posted November 30, 2008 Thanks everyone. I kinda have OCD so when I sink my teeth into something I become obsessed and read and study everything I can about it. TC Apparently, we're both afflicted with the same disease; so. you're probably gonna love this website! The magazine rack in my 'throne-room' is getting filled up with hard copies of this stuff. http://www.valvewizard.co.uk/ Gil... Link to comment Share on other sites More sharing options...
cGil Posted November 30, 2008 Share Posted November 30, 2008 SEwatt isn't back online just yet, but I found another source for that cool Blackheart footswitch gain mod. http://www.rowbi.myzen.co.uk/Blackheart/Documents/BH5H_boost_FS_MOD.pdf Gil... Link to comment Share on other sites More sharing options...
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