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Peavey Valverb help please n thanks!
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AndyFromDenver
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#1
3rd January 2012
Old 3rd January 2012
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Peavey Valverb help please n thanks!

*edit: scroll to #11 post for my mounting contraption!*

Hey!
I bought a valverb recently; it rules.
I'm swapping out the no name tubes.
(2 12ax7 and 1 12at7).
1. Any recommended tubes? I've ordered a pair of jjs and ehx to compare.
2. There is mention of a simple mod to help the tremolo not drop out slightly when engaged, but all the links are from years ago and dead.
I dl'd the schematic and would be happy to post if that is helpful.

Thanks!! I really love this thing and want it sounding it's absolute best.

Also, I'm in the planning stage for an enclosure that won't vibrate the springs for live use. Will post build when I come up with something.

schematic from web:
Attached Thumbnails
Peavey Valverb help please n thanks!-valverb.gif  
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4th January 2012
Old 4th January 2012
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Quote:
Originally Posted by AndyFromDenver View Post
Hey!
I bought a valverb recently; it rules.
I'm swapping out the no name tubes.
(2 12ax7 and 1 12at7).
1. Any recommended tubes? I've ordered a pair of jjs and ehx to compare.
Quite Frankly? Ebay. Search for whatever tube it is you're looking for, and look for the used ones in groups that look old and that don't have a name in the auciotn title. Then look at the picture, or ask the seller what the name on it is. If it's old, chances are it's good, and if you only end up paying a few dollars for it, and it's weak or microphoni, then you haven't lost much more than a couple dollars. The best is to find a lot from a seller who has a tube tester and lists his results in the auction description. I ended up with some killer RCA and Sylvania tubes that really brought out the life in my guitar amplifier.

Quote:
Originally Posted by AndyFromDenver View Post
2. There is mention of a simple mod to help the tremolo not drop out slightly when engaged, but all the links are from years ago and dead.
I dl'd the schematic and would be happy to post if that is helpful.

Thanks!! I really love this thing and want it sounding it's absolute best.

Also, I'm in the planning stage for an enclosure that won't vibrate the springs for live use. Will post build when I come up with something.
I don't know where to find this, but if you post a schematic, I think I'll be able to help you out. some people here know this on the tip of their fingers. why are they not answering?

anyway, it has something to do with the resistors on the output of the cathode follower for the transducer amplifier (the tube that receives the reverberated signal and sends it out to whatever amplifier you're using).
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4th January 2012
Old 4th January 2012
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By the way, If you really want to know the best 12xxx tubes ever made were from Telefunken, Brimar and Mullard. according to Mr Weber in hos book "A hip guide to Vintage tube amplifiers". Which I recommenr for someone like you.

You might also want to look at : Antique Electronic Supply

have fun and DON'T get electrocuted... discharge those caps! (I think you know already, and by now you probably have a tool (1K 10W resistor) to discharge your caps)

Cheers!
AndyFromDenver
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4th January 2012
Old 4th January 2012
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I'll attach the schematic to the original post
Ok thank you!!. I probably shouldn't have mentioned the tube thing, cause i'm not really a tube hunting type person (probably to the delight of you all ). I'm thinking as long the new ones i'm ordering work i'll be happy. When I bought it the 12at7 tube wasn't glowing and I took it to a tech for replacement, but he was out of 12ax7s cause he was building an ac30 for a customer.

Thanks for the friendly advice!!! I saw so many posts about how simple it was and thought i'd ask. I'm still super green. Yeah, I have been safely discharging the capacitors with the little hook ends and my multimeter, it takes foreeever and I do need to build a little resistor tool. I'll use the value you mentioned and splice it between some alligator clips

I got a couple more books for Christmas and will look into the one you mentioned.
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5th January 2012
Old 5th January 2012
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OK, cool. You seem to be on the right path, if there is one lol!

You know what? You might consider using a toaster as a discharge tool. It could work. The reason why I suggest this is for three reasons:
- it's free, everybody owns a toaster (even me)

- it has virtually all the power handling capacity you'll ever need(1000W or more) to discharge any capacitor you'll encounter (no, not that type of capacitor!)

- if it doesn't work it will give your significant other a good reason to go buy a new one. Even if it's with your money.

Here is the catch: I don't know if it will work. A toaster uses AC and caps charge DC. So applying 300VDC on a toaster element will put more of a stress on it than necessary. It could overheat, meaning your toast could be darker than desired, if you so wish to discharge your caps in the morning.

IF the caps are charged with less than that (maybe around 100V) then that shouldn't harm the toaster.

Note: this will only work with old type toasters. The new ones with microcircuits and all that $h it will probably be damaged by this process.

I guess you can scratch that idea. Unless you have nothing to do with an old toaster.
AndyFromDenver
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5th January 2012
Old 5th January 2012
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Lol. I made a resistor with alligator clips thing per a DIY web page. Works super fast. I changed the tubes and it seems more quiet and improved.
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5th January 2012
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Super!
I'll take a look at this schematic later on. It should be way simple.
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5th January 2012
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Hmm, OK so this thing has tremolo too?
I saw the LDR on the bottom right of the schematic and started to wonder why they would have used this to switch the reverb in/out. Q101 and Q102 seem to be some kind of a astable multivibrator circuit, with either VR106 or VR107 being the depth and speed controls. I don't really know.

About the cutting out mod, I believe the issue lies in the fact that the incoming audio from the tone control gets completely shorted to ground when you bypass the reverb circuitry. It does this by means of K1a and K1b. If you insert a 1K resistor in series with that junction and the output of the tone stack, it will prevent a complete short (whcih would cause an immediate discharge of the tonestack controls capacitors to ground) of the audio signal. 1K is insignificant compared to 250K, which is the load resistance.
here is a picture of where you need to add the resistor.

I do not guarantee this is what will work! It's just my guess at it.


COMPLETELY DISREGARD WHAT I WROTE. I DID NOT PROPERLY READ YOUR QUESTION.

Here is the info you seek: http://blueguitar.org/new/schem/peav...es/valverb.txt
look at the end you 'll find them talking about replacing the LDR. supposedely you were able to get the part from Peavey.

I thought you meant "there's a volume dropout while using the reverb" not tremolo. Makes perfect sense now.
Attached Images
File Type: bmp valverb_nocutout.bmp (931.2 KB, 452 views)

Last edited by 2N1305; 5th January 2012 at 07:33 PM.. Reason: corrected wrong info.
AndyFromDenver
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5th January 2012
Old 5th January 2012
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Yay cool!! Thanks! I'll look into that link. (edit: ill try again but i think thats a dead link...) Yeah the tremolo is really nice compared to my Princeton. It's more of a square wave. I don't really notice the drop out and people were stating it happens when the footswitch is used. I may just leave well enough alone.
I'm still gonna post a pic when I come up with an enclosure that minimizes vibration. I'm now thinking a collapsible Contraption similar to a mic shock mount. Tbc....

I really appreciate your posts!!!
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5th January 2012
Old 5th January 2012
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Thanks, I'm happy about that!

the modification, in case you can't see the link (I was able, actually I just browsed through a couple of hits on google) is this:
The original Light-dependant-resistor is prone to thermal degradation, which we all know in a tube unit, can be a big problem. therefor Peavey has admitted this (from what I can understood) and will seel you the correct part to replace it. I would simple find a substitute, but knowing exactly what MPN that was is another story...
To make things a bit more complicated, the LDR is DUAL. Meaning it has two LDRs inside it. Probably to achieve a greater Light-to-dark resistance ratio.

now I am wondering was the original problem the fact that the level was too low, or it was actually cutting out?
AndyFromDenver
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7th January 2012
Old 7th January 2012
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Low tech solutions for a high tech world presents:

My spring mounted spring reverb stabilization apparatus. *an awed hush fills the room*
Yay or nay
Attached Thumbnails
Peavey Valverb help please n thanks!-imageuploadedbygearslutz1325953380.232758.jpg   Peavey Valverb help please n thanks!-imageuploadedbygearslutz1325953406.836965.jpg  
#12
8th January 2012
Old 8th January 2012
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Quote:
Originally Posted by 2N1305 View Post
[...]

I don't know where to find this, but if you post a schematic, I think I'll be able to help you out. some people here know this on the tip of their fingers. why are they not answering?

anyway, it has something to do with the resistors on the output of the cathode follower for the transducer amplifier (the tube that receives the reverberated signal and sends it out to whatever amplifier you're using).
It's not so much a mod as it is a repair. It's simply replacing the LDR component. They pretty much all got wrecked by solder heat during manufacture and the damaged component causes the volume drop. Phone Peavey parts Department and asks for the LDR for a Peavey Valverb. It will be about $5.

Find the part on the circuit board, replace it being careful not to heat the legs up too much. Done. No mod, just a swap.
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AndyFromDenver
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8th January 2012
Old 8th January 2012
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Quote:
Originally Posted by travisbrown View Post
It's not so much a mod as it is a repair. It's simply replacing the LDR component. They pretty much all got wrecked by solder heat during manufacture and the damaged component causes the volume drop. Phone Peavey parts Department and asks for the LDR for a Peavey Valverb. It will be about $5.

Find the part on the circuit board, replace it being careful not to heat the legs up too much. Done. No mod, just a swap.
Yay Travis Brown! I'll do that. I wonder if some are ok, cause though I notice a slight volume decrease when I turn up the trem I just chalk it up to the effect. I'm going to inquire if they still have the part anyway.
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8th January 2012
Old 8th January 2012
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Quote:
Originally Posted by AndyFromDenver View Post
Low tech solutions for a high tech world presents:

My spring mounted spring reverb stabilization apparatus. *an awed hush fills the room*
Yay or nay
well that works! Good thinking

So it's made of steel? (it has to be springy and resilient)

The next step would be to mount the unit in a box with its own little shock mounts. Like 16 springs (or 4, one on each corner, front and rear)

Good work!
AndyFromDenver
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8th January 2012
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I thought about making a box with springs like you mentioned, but I think this will work other than being a little funny looking!

I was soo close to using the champ clone and valveverb at a gig last night, but last minute chickened out and used the Princeton reverb Next gig I'm going to elicit all the wtf's and bring the champ verb combo! It's really stable and is velcrod to the apparatus which is wedged under the amp handle, and it's super springy I've jumped in front of it and it doesn't make the thunder.
AndyFromDenver
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9th January 2012
Old 9th January 2012
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Alright. Clearly I didn't follow the thread with the dead schematic link all the way down cause they have a part # and everything for the LDR.



I ordered the part. The lady in the parts dept. almost ordered something totally different cause she entered the wrong part #, and it was going to be $1.25 (minimum order of $5 so i'd have gotten 3!!). But right at the end we figured it out and it's a dual light dependant resistor? So we cleared it up and it's $14.50. I'm going to preemptively state I may need help locating it on the pcb if it looks different from the original after 20+ years. I did google what the symbol will be and am checking the schematic.
This has been a good learning experience! Thanks for putting up with me
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9th January 2012
Old 9th January 2012
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hey hey, not at ALL! it's been fun. That LDR is dual, and it has obviously five pins (two for the led and three for the LDR pair, one being common to the two LDRs)
it should be black and have two pins on one side and three on the other.

cheers!

2N
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9th January 2012
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Quote:
Originally Posted by AndyFromDenver View Post
[...] I'm going to preemptively state I may need help locating it on the pcb if it looks different from the original after 20+ years. I did google what the symbol will be and am checking the schematic.
This has been a good learning experience! Thanks for putting up with me
Looks the same. Easy to spot.

When installing, hold the LDR leg with a little pair of pliers. This will help divert the heat from the soldering iron contact. If it is so sensitive to heat that they wrecked the component to begin with, then better to be safe.
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13th January 2012
Old 13th January 2012
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Well I installed the new ldr. Used hemostats as a heat sink. That thing is a pain to disassemble!
Gotta take off the 4 obnoxious little springs holding the, err, spring to the chassis.
In typical life fashion it sounds the same so the original part was probably fine....

Thanks guys for your help! It was a good learning exp.
#20
31st December 2012
Old 31st December 2012
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Anyone ever look at a mod with the valverb to convert the reverb circuit to a preamp boost?
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31st December 2012
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you mean make it not be a Valverb?
#22
1st January 2013
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Yes, you could say that, Maybe sacrilegious I know, but I use it for the preamp and the tremolo. I'm a fan of the tube tremolo, and never use the reverb.
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1st January 2013
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Gotcha. I'm sure it can be done easily.
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