Custom Vibrolux Reverb - Mark Moyer Mods

[fezzy]

Nope, I dont remember any added hiss at that point. The only noticeable change was the 'thickness' of the reverb.

For tubes, I'm going to go with the Tungsol 12AX7 mostly and I'll order a couple of the Jan-Phillips 5751 so I can try out the degaining trick and see which I like better. The Sovtek 6L6WXT+ sound like the way to go for this amp.I'll post another update once I try out some different tube combinations.

Also, I'm gong to order a pair of Weber 10F125 speakers. I'm really excited about getting those in the amp. Currently, I have the stock Jensen P10R (25w 8ohm) that came with the amp. They sound good at low-medium volumes but when really pushing the amp they sound so damn muddy-ish I can't imagine anyone enjoying that sound. They just dont seem to handle low end very well at all.

What speakers are you guys using?

Also, I found on another thread a guy using a combination of Weber F150 + A125. That seems like a great way to take care of the super high-end and pretty deep low-end. Thoughts / Suggestions?

[twangmeisternyc]

Most like the Weber line of speakers. The one you selected is a ferrite, so that is a big difference right there. Those Eminence Ragun Cajun's show up in a lot of threads, too.

My other baffle is a Jensen C15N 4ohm 15" Ferrite Ceramic...very 60's in its design. Definitely, higher highs and lower lows, real clear...my guess is it may only start to push a bit at loud volumes...not sure it would break up at 40 Watts...

That mismatch between speakers was used a lot back in the day. Trying to remember which makers actually did that right from the factory - not as uncommon as you might think at first glance.

Also, remember to wire the pair pos-pos, neg-neg when you are switching things all around - if not, you get the cancel out effect with one starting forward and the other going backwards when you strike a note. Take a digi picture first!

[fezzy]

Also, remember to wire the pair pos-pos, neg-neg when you are switching things all around - if not, you get the cancel out effect with one starting forward and the other going backwards when you strike a note.

Will do. I once wired a 4x12 cabinet incorrectly so the speakers where out of phase with each other. It feels like your brain is being ripped apart from the inside. Haha :)

[twangmeisternyc]

All my parts and tubes arrived in the mail this afternoon. Ordered a couple other caps for the reverb circuit, too, a 1000pF and a 2200pF ceramic disc.

Need to go get my multimeter and strippers, some wire, and also try to find those small fuses so I have a spare. More on the mod's next week.

[kcwm]

Can you post a clip of your amps with the mods done?

There's a guy on the local craigslist selling one of these that I might be able to make a trade for (and perhaps eventually trade for a DRRI). My biggest complaint about the Vibrolux was the hiss when the tremolo was on.

Thanks!

[twangmeisternyc]

I have no means to post sound clips...nor do I think you could make any determination from one.

Hey Fezzy,

I was able to collect all my stuff this weekend, and was also fortunate that my dad had some 3M aluminized foil just like the RF shielding seen across the underside of the top of the cabinet.

Those 5*20mm, 10A, 250V fuses aren't easily found retail...but this link should be helpful if you want to order spares.

http://www.alliedelec.com/Search/Sea...BA1C006928E17F

There is no minimum order...I placed mine this morning, will be a couple days before I expect to receive via USPS mail.

That fuse is a funny rating, too. It must be taking into account a maximum failure of the power tubes/transformers as well as adding the power from the tray of storage capacitors.

[fezzy]

KCWM - your best bet would be to play one for yourself. In the end its just another good sounding fender amp. Everyone has different playing styles so what sounds good to me might sound lame to you and so on. Definitely not a good idea to buy a piece of equipment because someone else sounds good through it. :)

Thanks for the link twangmeister! I was looking for one of those fuses over the weekend and had absolutely no luck. How are the other mods coming along?

[twangmeisternyc]

I'll get onto the Reverb Cap next...hopefully tomorrow.

I need to stare at the schematic again regarding splitting the two channels. I need Reverb on the Normal channel for some of my guitars...not ready to give Normal up yet.

Jumpering the Bright cap in and out is a possible solution, but I think there may be an elegant way to jumper the Reverb instead between channels with a switch.

We'll see. As we both know, in a live playing room environment, none of this really matters. The idle hiss is a non-issue short of a quiet setting, mic-ing, or recording...

What is nice about the concept of the amp is that you can get both the tubes to go over-the-top, as well as the speakers...so, those nuances are part of the sound in just a single combo.

What we are doing is steering things a bit for different situations. I have 3 acoustics with piezos, and 3 electrics...every one with a different pick-up and a different sound...so, my ideal plan is to know all the permutations...96 of them. Changing the tubes around last week changed my settings...still working through those new combinations.

[kcwm]

Fezzy, I can't play one with the mods done. Of course, I can play one WITHOUT the mods, but I've already done that...so it'd serve no purpose.

I've played on a CVR and made the, apparently, controversial statement that it sounded better than the DRRI. But, it was noisy. If the mods are made to reduce the hiss, I'd like to hear clips of it.

I'm not asking people to sound good. I just want to hear the difference the mods make. The memory of the hiss is still familar.

[surfcaster]

hi guys. i am not sure but i have understood that 5x20 250V 10A is a difficult fuse to found for you. is it right? if it is so, you will only need to give me a shipping address, as this is the most common type of fuse here in Spain. i will gladly send to you as many as you need.

[twangmeisternyc]

I got on to the Reverb C16 capacitor mod this early afternoon. Took a bunch of photos, wrote down wire colors and connections for all the "fast-on" spade connectors, etc. Those "fast-ons" were really tight...I had to loosen those I needed to unplug first with a small screwdriver...too tight to just yank off.

7 screws to release the PCB...all the Vol, Treb, Bass, Reverb, Speed, Intensity pots...1 ground wire screw. I only needed to release 3 of the "fast-on" wires to have enough access to remove and replace the cap.

I used a Ceramic disc 3300pF, 3000V capacitor.

So far, I have only tried just my little 1916 Gibson L1 with a piezo...LOTS more reverb, no real added hiss compared to the other 500pF capacitor. Sounds great. Need to work through all the other guitars now...

Thanks for the offer Surfcaster...I think this source I found should be OK...they sent a shipping notice this morning for the 5*20mm 10A 250V fuses

[twangmeisternyc]

The Byrdland sounds great, too. The depth of the Reverb compared to factory tubes and capacitor is an order of magnitude better. I think the higher gain Sovtek 5751 as the reverb driver is helping a lot.

[twangmeisternyc]

Have now played all but my old Epi Emperor through the 2-10 AlNiCo's, it's out for a new nut and a little fretwork. Only the Gretsch sounds a little in need of something...not bad, but the TV Jones pups and those unique controls might have liked the higher gain pre-amp. I'll try it first when I go through the same progression with the C15N baffle.

[twangmeisternyc]

The Gretsch sounds great through the C15N, must have been the way I tested before...

[twangmeisternyc]

My next step is the shunting capacitor, C20, I'll get on to that over the weekend. I'm hearing a little something, whatever a "parasitic" is, more so just a ringing that seems to want to lead to a feedback moment - but, doesn't. I think from Mark's description that C20 is fairly benign...more so some command and control element...we'll see. ;-)

[twangmeisternyc]

5*20mm 10A, 250V fuses came late yesterday...I think now I have a lifetime supply of most everything ever needed to manage a CVR, mod a CVR, OR EVEN MAKE A CVR. ;-)

[fezzy]

Thanks for all of the updates twangmeister! I'd like to see some of your pictures just for comparison purposes. Sorry I havent posted in a while. I'm waiting on my tube order to come in.

Also, I've experienced that ringing you are talking about. It went away about 2 weeks ago so I never had a chance to try and track down the cause.

[twangmeisternyc]

I put the next mods on hold this weekend as I decided to sell something on Craiglist for which I needed the amp to function. I also wanted to get the Epiphone back from the shop and give it a run through with the new set up.

I spent a lot of time comparing the two schematics in the interim, hoping to see an easy way to separate the channels, and make reverb selectable to either. While it is certainly do-able...I'm seeing a few limitations. The easiest is to work the Moyer mod with a DPDT switch for the reverb lead...and at the same time disable the other channel completely. So, it is a BRIGHT channel reverb only, and the NORMAL without...or...NORMAL with reverb and BRIGHT disabled. I am still staring at it, but I think that is the safest. I do not want it to be so complex I cannot even remember! There are a few spots that switch can be mounted, it doesn't need to be all that big.

Also, the C20 shunting cap, and the R23 resistor both would seem to help reduce the idle hiss if I foregoe the Moyer reverb mod. C20 adds a little "river" between and ahead of the two 6L6's that allows a balance of power on the very low spectrum should one side get well ahead of the other. R23 determines how revved-up the pre-amp gets, as well as affects the mix ratio with the reverb. Higher ohms should add headroom and more reverb as I see it.

I like what I am hearing right now, and I do not want to be tearing this thing apart 6 times just because I can. My guess is the integrity of the assembly was conceived with only a couple interventions into the PCB and other components in its lifetime...it is not built like a 50's RCA TV.

Only other note is I put a GE NOS 6201 in for the Reverb driver, essentially bringing the gain back down to factory settings...it's a little warmer than the Sovtek 5751. I also put a GE NOS 5751 in the NORMAL channel pre-amp...still comparing that to the JAN-Philips 5751.

[twangmeisternyc]

I did what I thought was an interesting test this morning. I went through a series of tube movements for V1 and V2, listening for idle hiss and then giving full volume. What I wanted to discern was where the noise comes from. One might think that without a pre-amp tube it in, a channel wouldn't even make a whisper. WRONG!

The end of the story is the BRIGHT channel is relatively quiet, and the NORMAL channel is the majority of the hiss. From the schematic, the fact that the NORMAL channel V1B socket 6 gets powered via the V2B socket 6 by a jumper, and not straight from the PCB board via the "X" source voltage used in the Vibroverb and the Moyer mod seems to be it. That jumper wire, and the relatively low resistance through R22 and R23 appears to be the noise.

[twangmeisternyc]

I think the GE NOS 5751 is quieter and a more full tone in the NORMAL pre-amp. Somebody on another board suggested it...I agree.

[twangmeisternyc]

Hey Fezzy,

I was laughing out loud at myself yesterday...it's like 15 degrees F outside, wind howling, both radiators full blast, my room humidifier full blast...I can barely hear myself play at my regular settings, yet, I'm trying to reduce the idle hiss to a church mouse squeak!

I'm going to do the R23 and C20 mods next...more on those soon.

[twangmeisternyc]

I did the C20 shunt using a 100pF, 3000V Ceramic disc capacitor, and changed the R23 value to 82k ohms 1W Metal Oxide resistor this morning.

Results so far are what I expected...feels more de-gained, reverb is stronger. I'm using the 2-10 AlNiCo's right now, and have tried the Strat Plus and the Byrdland...both aren't quite as shrill in the BRIGHT channel, so, maybe I would also comment that some of those "overtones" or "parasitics" are more tame.

I had to release a few more of the "fast-on" connectors to be able to get to C20...and I am a little surprised at how light gauge all of the input jack and potentiometer wires are...they look very easy to break, and just from being bent over a couple times like how they act while disassembling and reassembling the chassis.

I'm going to play my CVR like this for a while...since I cannot really go to higher volumes in my apartment, and I'll wait until I get more space to "turn it up" before proceding on any other mods.

I'll add more comments as I have them...

[fezzy]

I've ordered a bunch of tubes today. When those get here I'll post updates on my different combinations and results.

All of those white wires that run from the main board to the daughter pot boards I've broken and had to resolder. Since I know I'll be taking this thing apart very soon to install the bias pot I'm going to replace nearly all of the original wires with some good solid silver core wire with cloth wrapping. I can't believe how crappy the stock wire is in these amps. Its pretty amazing. Some of the wires will pop off if you look at them wrong. lol

Recently I've been playing the amp at loud volumes and have come across a few weird static sounds here and there... Not sure what it is yet but I'll take a good look around next time I take it apart.

More updates soon! Keep us updated on your progress twangmeister.

[twangmeisternyc]

I am a happy camper. I put everything back together properly this morning as if from the factory. I think I addressed my initial peeves...understanding the REV/VIB foot pedal "pop", the idle hiss, and the quality and amount of reverb. Three interventions, and it still all works!

Trying to keep the volume down for the "neighbors" has always been a priority, but I can gauge the component and tube changes pretty well. A lot of times I play with just the guitar volume slightly on, and the amp volume at say 2.5 to 3...and that gives one kind of sound. But the more full, chimey sound certainly comes the other way...guitar volume full open, and the amp volume "at maybe" 1. Very full and resonant, and I know it gets better if I let it go higher.

[twangmeisternyc]

The Strat Plus with the Gold Lace sensors is just loving this new set-up. The 2-10 AlNiCo's are much happier with the de-gained circuitry and tube selections. I have more reverb at 3.5 than I did before at 10. Those in-between, position 2 and 4, pickup positions cannot be any more fun...clean, true, nice rock-a-billy/bakersfield tone. And really, really quiet.

I've opt-ed for the guitar volume to be at about 80%, leaving a little bit of something if I need it, then having the amp volume set as loud as I think the people "upstairs" can tolerate!

IT SOUNDS GREAT!

[surfcaster]

The Strat Plus with the Gold Lace sensors is just loving this new set-up. The 2-10 AlNiCo's are much happier with the de-gained circuitry and tube selections. I have more reverb at 3.5 than I did before at 10. Those in-between, position 2 and 4, pickup positions cannot be any more fun...clean, true, nice rock-a-billy/bakersfield tone. And really, really quiet.

I've opt-ed for the guitar volume to be at about 80%, leaving a little bit of something if I need it, then having the amp volume set as loud as I think the people "upstairs" can tolerate!

IT SOUNDS GREAT!

hi twangmeisternyc. you seem sooo happy with the result of your work. as i told you, it is a bit difficult for me not losing at some point because i can't understand the whole sense of some phrases in english. would you do a little summary of the mods you have finally done to your amp? thanks!

[twangmeisternyc]

Let me try to make it easy...

1) I tried the footswitch ground mod, but then returned to the factory way. So, I did not use this mod.

2) I changed C16, the "reverb cap", to 3300pF, 3000V ceramic disc from the factory value of 500pF, 1000V ceramic disc. This made for a lot more reverb, and a lot more depth of sound. 3300pF is the standard value in most of the early 60's Fender spring reverb amps.

3) I added C20, the capacitor shunt between the two Power Tubes, using a 100pF, 3000V ceramic disc capacitor. This believe this change allows for over flow exchange of power on the low frequencies between the two tubes, preventing one tube from working too hard when the other is available to do more.

4) I changed R23, the primary resistor measuring power to the pre-amp tubes to 82k ohms 1W Metal Oxide type from the factory setting of 47k ohms 1W Metal Oxide type. This change reduces the power to those tubes, essentially de-gaining the pre-amp.

[twangmeisternyc]

My tube selections are as follows:

V1- GE NOS (jan) 5751
V2- Jan-Phillips 5751
V3- GE NOS (jan) 6201
V4- Tung Sol 12AX7
V5- Tung Sol 12AX7
V6- JJ/Tesla ECC81
V7, V8- Sovtek 6L6WXT+

[Wilko]

oh and as for the '63 vibroverb, this basically converts it to that. there are a few other differences but not many. enjoy your VV!

uh... that GZ34 is a pretty substantial difference.

[JAM]

Let .

3) I added C20, the capacitor shunt between the two Power Tubes, using a 100pF, 3000V ceramic disc capacitor. This believe this change allows for over flow exchange of power on the low frequencies between the two tubes, preventing one tube from working too hard when the other is available to do more.

This is just to prevent parasitic oscillation on the output stage. Doesnt have anything to do with how hard the tubes are working. Too high a value here and you'll lose high end.

[fezzy]

I got my new tubes in and tried a ton of different combinations. Here is what I ended up with and am pretty content with at this point.

V1: Jan Phillips 5751
V2: Tung-Sol 12AX7
V3: Mullard 12AT7WA
V4: RCA 12AX7
V5: RCA 12AX7
V6: RCA 12AX7
V7, V8: TAD 6L6WGC-STR

I decided to change R23 back to 47k. The added headroom from Moyer's suggested mod is not beneficial to me and I think the amp sounds better when the preamp is hotter.

I've yet to install a bias pot. I will soon probably but Mark Moyers description of how to do it doesnt make a lot of sense to me. I've read it 10 times and its still confusing.

[twangmeisternyc]

I've been playing my old 1916 L1 Gibson and the 1940 Epi Emperor a lot the last couple days through my new LR Baggs Para Acoustic DI and into the -6db Normal input. It has taken a little while to dial in the best settings...but, wow, they both sound great.

Reverb at about 3, 2-10 AlNiCo's, gain set low, a little more presence on the Gibson than on the Epi, a little more bass on the Epi versus a little more treble on the Gibson...it's like a concert hall sound. Every nuance, real clean.

As said before, its nice to know we have flexibility..and when you want it "hot", that's available...and when you want it soft, that's available, too. And even if it is just a tube change.

I really like the way the Strat Plus sounds, too...played that for about an hour yesterday. The Gretsch in this set-up with the 2-10's likes the straight up open pickup settings the best..and the plain strings with the rocking bar bridge... it jangles a bit more.

Not sure why I say that..I think the Gretsch likes the higher efficiency ceramic magnet set-up on the 1-15 baffle. I need to switch back over and give that some more time.

[twangmeisternyc]

Just like before when I said it...the Gretsch likes the C15N baffle a lot more in the new arrangement. More distinct sound variations on the tone switch, and less of the plain string jangle...back to more the "attenuated-muted-yearning" coming of the rocking bar bridge. I get less reverb at the same settings using the Gretsch as well. Still trying to figure that one....

[twangmeisternyc]

The Strat Plus always liked the 2-10 AlNiCo's better...but now the difference is even greater. It sounds rather crappy with the 1-15...noisy, thin, yeeetch!

[twangmeisternyc]

I plan to order the extension cabinet this next week to make my Vibro-Lux STACK. I think that best before I start cranking the volume higher, making more mods, ...plus it will be a lot easier to switch between speakers.

I think I am starting to wear out the grill cloth on the corners every time I switch using my current method two baffle set-up. And I want to hear the two speaker sets in combo...bass of the 1-15 hovering the floor, the 2-10's angled back into the ceiling. And I want to hear it all really LOUD!!!

[twangmeisternyc]

Put on order from Mojotone...hopefully here by mid next month.

[twangmeisternyc]

Hey Fezzy,

My extension cabinet order from Mojotone has shipped, once I get back from holiday I'll get you a couple pics of my "Vibrolux Stack". Knowing that when I use both the 2-10 AlNiCo's, and the 1-15 Ferrite in tandem I'll be at 2 ohms...I figured de-gaining the pre-amp by putting R23 at 82K ohms would be a good thing. I hope this comes together...been planning for over a year now.

[twangmeisternyc]

Mojotone did a great job...just really clean, well thought out work. Working through the wiring connections, etc., need to finish a couple speaker cables...

Also, looking for a nifty way to rock the CVR back a bit w/o using the tilt back legs... probably a couple small black rubber wedge wheel chocks or door stops, maybe a rack...

UPS did try to spoil everything by gouging deep into the shipping carton, but "this time" I got lucky... I guess.

[twangmeisternyc]

Hey Fezzy...you still checking these posts? Tried to send you a few pics, ... your email addy failed.

TUKI covers on order...very, very pleased with the combined extension cabinet sound. Clean and true, quiet...

[fezzy]

hey twangmeisternyc,

Would love to see some pics. Send to fezzyis@gmail.com

Glad to hear your rig is working well!!