Guitar Gear Forum

Hello to you all. Just joined the forum a few minutes ago. I'm not much of a guitarist. By nature, I'm more inclined and proficient in recording and a novice at electronics. Recently bought a house and in the middle of finally building a proper home studio. Part of that process, I am acquiring a number of used guitar amps and getting them restored to the best of my abilities. The first endeavor is a little Vox VR15. As soon as I joined the forum I searched for any info on the tiny beast with no results. Any members with insights to the VR15, please share your knowledge with me.

Welcome to the fold brother - this is the best guitar/amp forum on the interwebznet!!!

Couldn't find any schematics, online, for the VR15. Anything wrong with it?

Thank you for the warm welcome.

Overall, the amp is in great shape. The pots were a bit scratchy but a squirt of DeoxIT D5 set those right. It still had the OEM 12AX7, which was functioning well but I replaced that with a Mesa Boogie unit and it is now more robust and Voxy.

There are three issues I want to address.

First, there is a bit of 60Hz hum on the clean channel but dead quiet on the Overdrive. I was wondering if this is normal. I would have suspected the opposite.

Second, I want to replace the OEM 8" speaker with a 10". Does anyone have a recommendation? I suspected there will be some issue ase the speaker is mounted to the front of baffle instead of the rear. I suspect some restrictions because of clearance with the grill cloth baffle.

Third, the biggest cosmetic problem is the grill cloth. It has become partially detached from the center top of the baffle. While the other three sides are stretched and stapled to the back of the panel, the top of merely glued to the very top of the panel. Any suggestions on how to deal with getting it stretched and reattached?

I attempted to upload a couple of photos of the speaker panel and grill panel but the editor rejected them. I suspect the file sizes are to big. Going to resize them and try again shortly.

Any suggestions or insights will be greatly appreciated.

How old is your amp? Possible filter caps if old.

I don't think I'd bother trying to reattach the grille cloth, unless it's truly vintage stuff. Source out replacement or rock the fuk outta it

Photos are best to host on another service and link to your postings here. Imgur and Photobucket work well.

Very interested in your studio build. Did one, myself, a couple years back. I documented it in a DIY thread (see my signature below).

Hello G-Space. Thanks for joining in.

As understand it, the VR15 was only in production during the 2005-2006 period. So, 12 to 13 years old.

I did a visual inspection of the filter caps and "wiggle" test. They "look" in perfect shape, but that can be deceiving, They passed the wiggle test; very solidly mounted. I haven't flipped the board over to inspect the solder joints. Should probably do that and reheat them and add a touch of fresh solder. Might do the trick. Overall the 60Hz hum is small but I would like none. A work around is I can adjust the overdrive channel to a very clean tone.

The grill cloth is a minor issue and I thought would be a simple matter of stretching and stapling. I would like to get in as near new condition as possible but I could live with it as is.

The studio build is going to take some time. I've got all the recording hardware ready to install and I'm pondering on how to best lay out the physical studio, i.e single room for the recording equipment and performance space or a "classic" separate control room and separate performance space. The 'purist' in me says a proper studio has a dedicated control room, but I fear I've not enough space. I've got 2 Hammond spinet organs (a M3 and a L-147), a large Hammond Tone cabinet and a Leslie 145. That Hammond arsenal takes up quite a lot of space. The build is the stereotypical basement and I'm researching how to best sound dampen from the rest of the house. Plus my carpentry skills are rudimentary at best. I would be interested in your insights.

60 cycle / 120 cycle hum - good vid to watch... even though, your amp is Transistor.
[video]https://www.youtube.com/watch?v=GrVtX0QGNls[/video]

Welcome, DrLunk. I know nothing about that amp, but am looking forward to hearing some of your recordings.

Welcome, mang!

^yup. that's what I thought

ajaxlepinski, thanks for the link.

I saw that vid last week and learned the difference of 60Hz and 120Hz hum, but had forgotten what it meant circuit-wise.

you saved me some searching

RUBATO,

Nice to met you. Don't know the significance of the link you left.

The link is in my signature so it will always be in my posts, though I'm gonna take it out now that you've pointed out that it's still there because it was only there to bother the person for whom I made the clip.

Welcome DrLunk!

DrLunk wrote:Hello G-Space. Thanks for joining in.

As understand it, the VR15 was only in production during the 2005-2006 period. So, 12 to 13 years old.

I did a visual inspection of the filter caps and "wiggle" test. They "look" in perfect shape, but that can be deceiving, They passed the wiggle test; very solidly mounted. I haven't flipped the board over to inspect the solder joints. Should probably do that and reheat them and add a touch of fresh solder. Might do the trick. Overall the 60Hz hum is small but I would like none. A work around is I can adjust the overdrive channel to a very clean tone.

The grill cloth is a minor issue and I thought would be a simple matter of stretching and stapling. I would like to get in as near new condition as possible but I could live with it as is.

The studio build is going to take some time. I've got all the recording hardware ready to install and I'm pondering on how to best lay out the physical studio, i.e single room for the recording equipment and performance space or a "classic" separate control room and separate performance space. The 'purist' in me says a proper studio has a dedicated control room, but I fear I've not enough space. I've got 2 Hammond spinet organs (a M3 and a L-147), a large Hammond Tone cabinet and a Leslie 145. That Hammond arsenal takes up quite a lot of space. The build is the stereotypical basement and I'm researching how to best sound dampen from the rest of the house. Plus my carpentry skills are rudimentary at best. I would be interested in your insights.

If that's a tube amp, DO NOT screw around with filter caps, unless you know how to drain them and/or assure they are drained. Some amps have "bleeder resistors" that take care of this, but you can never be certain unless you take proper cautions. Filter caps store up HUNDREDS of volts (350V-500V is common), and will kick your ass into next week. If you're not in the obituaries after that, you'll be lucky if you have any brain cells remaining. Not kidding dude.

With that amp being 10 or so years old, chances are good that the filter caps are ok, but you won't be able to tell by wiggling them. Generally, caps will be good for 15-20 years at least, with really bad ones exhibiting 'blisters' or bulges on the ends of the casings.

Where are you building your studio? What are your objectives? If sound mitigation is what you're after, you need to decouple like crazy. Do check out my studio build - mine is a single-room studio built in the middle of my garage, with the only direct connection to the outside being the floor. We built up the walls using staggered studs, and I'd say we're probably at least 80-80% soundproofed. I documented the shit out of it. See the link in my signature.

Even if you're not building a complete room within a room, it's still possible to build decoupled walls within an existing space, and can give you some pointers on that.

Welcome, pal!

You've finally arrived at the greatest guitar forum on the interwebz!

G-SPACE

Thank you for taking the time for such a thoughtful post. I described myself in my introduction as an electronics novice. This is true in that I do not have a really deep understanding of most of this "stuff". However, I have been knocking around with this for going on 40 years, mainly under the guidance of a very old friend who is a trained certified tech who came up in the late 60s working out of his garage repairing TVs and audio equipment. I spent countless overnight sessions with John assisting him (Stand over there, hold this but don't touch the end of the wire) and picking up a gut-level respect for High Voltage AC. If you've been on the wrong end of the flyback transformer of a misfiring 25" RCA all tube TV, you know what I mean. Doing basic inspection and minor repair is something I have some experience at. The last 6 years has been spent restoring various Hammond organs and getting guidance from the various members of the Organ Forum. From all this I learned one thing: always be grateful and listen closely to those who obviously have more experience and knowledge than you. Not only will this save you time and frustration but quite literally save your life. So again, thank you.

The purpose of the "wiggle test" of the filter caps as well as other components is a quick and perhaps lazy way the find any solder joints that have weakened and the component is jangling around on the circuit board without pulling the board to inspect the solder joints initially. A tip I got from the Organ Forum and something I automatically do anymore on first inspection. A visually inspection of the filter caps is also something out of habit I do to spot any obviously bloated, swollen or leaking electrolytics. You wouldn't believe the messes you will find in a 60 year old Hammond M3. And before I touch the filter caps, I always ensure they have been discharged.

You're right, the filter caps are probably fine. And the slight hum I'm hearing may be just the nature of the VR15. Again, from my experience on the Hammonds, I have learned to expect that a properly designed, built and maintained amplifier should be whisper quiet. Did Vox design and build the VR15 to the tolerances of a '58 Hammond? I seriously doubt it.

As to the studio build, I plain to read through your post this weekend with great interest. The quick overview of my build is that is a basement installation in a room of very unfortunate limited dimensions: barely 7ft tall, 8ft wide and 30ft long. A nightmare for standing waves. I plan to do a "room within a room" and plan to use a shitload of Roxul. A primary design concern is that it is a given that the studio will house the following: Hammond M3 organ, Hammond L-147 organ, Leslie 145 speaker and a very large Hammond Tone cabinet. Those items burn up a bunch of floor space. I doubt I will be able to build the classic separate control room and performance room, though, that's always been the dream and I haven't given up on it yet.

By the way, I love the image of Puddy you use as your avatar.

Good to hear you have knowledge of caps and instant discharge. One of the reasons we make sure to reiterate is not only for the poster, but also for others who read - we don't want someone getting the idea it's ok to muck around with their stuff.

BTW, I used to service old "green screen" CRT terminals back in the 80s, and definitely saw what instant discharge looks like, using a grounded, heavy screwdriver (not the best way, I know now).

My studio ceiling is about 7'6", and fairly square, which is a separate issue. Room within room sounds like it might be a bit difficult in your situation - all my plates are 1x6, which means you'd loose about 1'3" plus an air gap on the side walls, and you'd lose at least 8" on the ceiling height. I'll try to post up some details in a bit for you to check out, and some alternatives to consider in your planning.

You might also check out Sex Panther's studio build thread - he built his in a basement, like you.

Besides Roxul, check out acoustic caulking (which I used between any drywall joints, wood framing, floor connections, etc), which you can get fairly cheaply from AVS.

One potential alternative you can try is Audiomute sheeting. I'm pretty sure some of the guys here have used them to help with sound mitigation.

To bring this thread to something of a conclusion, I reheated some dodgy solder joints on the input jack on the VR15. That greatly reduced the hum. I ordered a variety of 12AX7 from Sweetwater and swapped out the original China 12AX7B. The basic Mesa Boogie tube was the clear winner in terms of tonality and noise signature.

In addition to the VR15, I also have a Vox AD30VT and, just acquired this weekend, a Vox Cambridge 30 Twin Reverb 2x10. All three of these use the China 12AX7B. The AD30VT had the same background hum as the VR15 while the Cambridge was dead quiet. Trying out the variety of 12AX7 in all three amps, the Mesa Boogie consistently was the clear winner.

Hello.