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212 amp, one speaker blown, advice please.
Old 9th September 2020
  #1
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ggrey's Avatar
 

212 amp, one speaker blown, advice please.

Hello, I am in need of advice of those who have acquired more speaker load knowledge than I. Thanks in advance for your input.

I have a Peavey Classic Chorus 212 Scorpion amp with one of the 12" speakers blown/heavy distorted buzzing and am in need of using the amp, but have no funds to fix.

According to the manual the speakers are 8 ohm each. And the amp states it needs an 8 ohm minimum load, so I am assuming the 2 speakers are wired in series and not parallel.

My question is, can I disconnect the blown speaker and use the amp with only the one good 12". I realize the sound will change, but will it cause any damage to the amp.

Thanks!
GG
Old 9th September 2020
  #2
Gear Maniac
 

Quote:
Originally Posted by ggrey View Post
My question is, can I disconnect the blown speaker and use the amp with only the one good 12". I realize the sound will change, but will it cause any damage to the amp.
Tube or solid state amp?

If you just disconnect the bad driver chances are you will blow the good one as it will be acoustically unloaded and very easily overdriven. The way to minimize this problem is to disconnect and short the terminals on the bad driver... and hopefully there is enough good voice coil left to dampen it's cone movement. The single driver won't take as much power as the pair so you would have to lower the overall drive level.

If this is a tube amp it won't be happy with the change in load and could be damaged with only 1 driver connected, but a solid state amp doesn't care.

P.S. Just looked it up and appears it's a stereo solid state amp, in that case there is no problem with disconnecting 1 speaker but it won't produce any stereo effects anymore... yes it will sound different.

And if you disconnect the bad speaker be sure not to short the leads from that amplifier, tape up the + and - separately.
Old 9th September 2020
  #3
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ggrey's Avatar
 

Thanks for the quick response. It is a SS amp.

"The way to minimize this problem is to disconnect and short the terminals on the bad driver"

I am not very tech savvy...How do I do short the terminals?
Old 9th September 2020
  #4
Gear Maniac
 

You would just put a piece of wire across the terminals, but after looking up the model I don't think this will be necessary as it's an open back cab anyway, so just make sure the disconnected amp leads can't short together or to anything metal.
Old 9th September 2020
  #5
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Hey paul o. I think you should be very careful when talking about "shorting terminals" anywhere near an output load and especially to one not tech savvy. This is an open back cab so I don't see a major issue with acoustic loading anyway.

Hello ggrey. It is possible to get 12 inch 8 ohm speakers new or used for around 60bux. Is that a posssibility? That is not as good as an exact replacement especially if yours are the cast frame Scorpions, but they would work. In fact I just saw 2 x Peavey stamped frame 12s for 49.99 total for both on eBay. I'd look around.
Old 9th September 2020
  #6
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Thanks enorbet2 I agree replacement will be best, but at the moment not possible. Although I may have an old 8" 8 ohm I could substitute for the time being. I again assume that would be better than no speaker...?
Old 9th September 2020
  #7
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enorbet2's Avatar
Quote:
Originally Posted by ggrey View Post
Thanks enorbet2 I agree replacement will be best, but at the moment not possible. Although I may have an old 8" 8 ohm I could substitute for the time being. I again assume that would be better than no speaker...?
It will assuming you can fashion a temporary adapter so the acoustic properties are not compromised and the 8 can handle the power. Be careful with too high a Bass control setting, too.
Old 10th September 2020
  #8
Gear Maniac
 

Quote:
Originally Posted by ggrey View Post
Although I may have an old 8" 8 ohm I could substitute for the time being. I again assume that would be better than no speaker...?
How would you mount an 8" speaker in a 12" hole? Simply disconnecting the bad driver is the best temporary solution.
Old 10th September 2020
  #9
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Thanks for the input and recommendations. From above from paulo....

""""Just looked it up and appears it's a stereo solid state amp""""

And as such has one power amp per speaker. I have always understood you cannot power an amp without a speaker load. You risk burning out the amplifier circuits. True, or not?
Old 10th September 2020
  #10
Gear Maniac
 

Quote:
Originally Posted by ggrey View Post
I have always understood you cannot power an amp without a speaker load. You risk burning out the amplifier circuits. True, or not?
Does not apply to solid state amps.
Old 10th September 2020
  #11
Quote:
Originally Posted by ggrey View Post
Thanks for the quick response. It is a SS amp.

"The way to minimize this problem is to disconnect and short the terminals on the bad driver"

I am not very tech savvy...How do I do short the terminals?
DON'T DO THAT!!!!!!

How long the speaker lasts depends on its wattage rating.

The 212 Chorus has a stereo power amp, so each speaker has its own amp.

You can get a recone basket for the Scorpion speaker at your Peavey dealer and fix it yourself. It's just 3 bolts.

It is not advised to mismatch speakers in this amp, as it will make your stereo chorus sound lopsided.
Old 10th September 2020
  #12
Quote:
Originally Posted by ggrey View Post
Thanks for the input and recommendations. From above from paulo....

""""Just looked it up and appears it's a stereo solid state amp""""

And as such has one power amp per speaker. I have always understood you cannot power an amp without a speaker load. You risk burning out the amplifier circuits. True, or not?
NO.

You must not power a TUBE amp without a load. SS amps are different - you must not operate those with a load below the rated impedance.
Old 10th September 2020
  #13
Quote:
Originally Posted by ggrey View Post
Thanks enorbet2 I agree replacement will be best, but at the moment not possible. Although I may have an old 8" 8 ohm I could substitute for the time being. I again assume that would be better than no speaker...?
It must be the same or higher impedance. If the impedance is below rated spec you will blow the amp most likely. If it's 8 ohm it will probably work till it blows.

You can get a replacement basket for between $75 and $115, depending on source. Swapping in a new basket gives you a new speaker.
Old 10th September 2020
  #14
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Rick Dalton's Avatar
Quote:
Originally Posted by ggrey View Post
Thanks enorbet2 I agree replacement will be best, but at the moment not possible. Although I may have an old 8" 8 ohm I could substitute for the time being. I again assume that would be better than no speaker...?
May have missed it, but did you swap speaker leads? just to make sure it is the speaker and not the amp section? if not, do that first and if it is the speaker, lay it face down unbolt the magnate from the basket, be careful and pull it straight up, then have a look at the voice coil for debree, ware/rub marks on the inside of the voice coil were the motor may be rubbing, look for loose winding's/coil wires, if you find some try to get them back in their place and tac with a little superglue, (don't let it get away from you) Notice if the voice coil is deformed, you can tell easy, as that will be the first signs of rubbing, if its a slight rub area and not to concaved, use some 400grit sandpapper, wrap it around some soft foam rubber Pipe insulation,(the black tube kind,,, stuff the inside of it so its just a little larger than the voice coil diameter, you're turning the foam into a hone, use a felt marker and mark all the way around (zigzag) up and down the voice coil and use the hone, just turn this hone evenly 360% for 10 turns, then take a look for marker, see if its getting even and or going away, if not repeat (put a little felt mark all the way around zigzag up and down the voice coil and hone, check and once all marker is gone, blow out debree/dust, clean and reassemble very carefully. Once assembled you can push in on the cone evenly (around center Not in the center) and feel for smoothness, if it feels gritty like sandpapper you still have rubbing. You can repeat. Just keep an eye on the inside, that you're not sanding all the way through the bobbin to the coil wires. anyway, you've nothing to loose, and this does work, or i wouldn't be wasting my time, typing this. But first make sure you swap speaker leads, and see for sure. if you haven't already tried.

EDIT= acouple things, lay that amp on its back and play it for awhile, see if that helps, it could loosen debree, if you think if helped. use a vac a try to suck it, be careful you don't let the vacuum lock on. also if you end up having to take the speaker out, look over the cone and surround real good, push lightly around the outer/surround, you could have some separation/ cone unglued somewhere. it happens.
Old 10th September 2020
  #15
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enorbet2's Avatar
Quote:
Originally Posted by paul o View Post
How would you mount an 8" speaker in a 12" hole? Simply disconnecting the bad driver is the best temporary solution.
It is by no means ideal since very few 8inch speakers will handle that kind of power, but OP says he has no bux right now. It isn't at all difficult to make a plywood adapter that will bolt up like the original 12 but with a cutout for the 8. With decent tools it can be done easily in a half hour. Unfortunately that may be about how long it will last if he cranks it up. However bedroom volumes might be OK if he keeps Bass low..

I dunno but it seems to me a used replacement could be had for mowing 3 lawns or spending a day delivering pizzas, but whatever twirls ur beanie..
Old 10th September 2020
  #16
Gear Head
 
ggrey's Avatar
 

Thanks for the input John and Rick...Rick, I did not swap speaker wire or try your other suggestions, but will and report back the results.
Old 11th September 2020
  #17
Quote:
Originally Posted by Rick Dalton View Post
May have missed it, but did you swap speaker leads? just to make sure it is the speaker and not the amp section? if not, do that first and if it is the speaker, lay it face down unbolt the magnate from the basket, be careful and pull it straight up, then have a look at the voice coil for debree, ware/rub marks on the inside of the voice coil were the motor may be rubbing, look for loose winding's/coil wires, if you find some try to get them back in their place and tac with a little superglue, (don't let it get away from you) Notice if the voice coil is deformed, you can tell easy, as that will be the first signs of rubbing, if its a slight rub area and not to concaved, use some 400grit sandpapper, wrap it around some soft foam rubber Pipe insulation,(the black tube kind,,, stuff the inside of it so its just a little larger than the voice coil diameter, you're turning the foam into a hone, use a felt marker and mark all the way around (zigzag) up and down the voice coil and use the hone, just turn this hone evenly 360% for 10 turns, then take a look for marker, see if its getting even and or going away, if not repeat (put a little felt mark all the way around zigzag up and down the voice coil and hone, check and once all marker is gone, blow out debree/dust, clean and reassemble very carefully. Once assembled you can push in on the cone evenly (around center Not in the center) and feel for smoothness, if it feels gritty like sandpapper you still have rubbing. You can repeat. Just keep an eye on the inside, that you're not sanding all the way through the bobbin to the coil wires. anyway, you've nothing to loose, and this does work, or i wouldn't be wasting my time, typing this. But first make sure you swap speaker leads, and see for sure. if you haven't already tried.

EDIT= acouple things, lay that amp on its back and play it for awhile, see if that helps, it could loosen debree, if you think if helped. use a vac a try to suck it, be careful you don't let the vacuum lock on. also if you end up having to take the speaker out, look over the cone and surround real good, push lightly around the outer/surround, you could have some separation/ cone unglued somewhere. it happens.
This might work, kinda, but is not advised, as what you're doing is permanently altering ther magnetic gap, which is a crucial part of the permanent portion of the speaker, to save a replaceable part that has gone our of spec and will probably continue to do so. You're also going to get grit in the gap, which is a bad, bad thing.

DO NOT use super glue on a speaker. It dries brittle, so it will crack, and it degrades with heat and voice coils do get hot.

The best solution is to bite the bullet and replace the basket - you'll have a new speaker instead of a damaged used one with a kludged repair.

If the speaker is dead open, make sure that the problem is not a damaged tinsel lead-in wire between the speaker terminals and the cone. That CAN be replaced with no problem, using inexpensive material from any of a number of vendors. You'll need to be careful and use heat sink clamps to avoid having the solder wick into the wire, making it stiff. Look for "reconing supplies" on Google.

If you replace the tinsel lead, make sure that it has enough slack to allow for full cone excursion, but not so much that it can short against the frame or the other lead.
Old 11th September 2020
  #18
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Rick Dalton's Avatar
Quote:
Originally Posted by John Eppstein View Post
This might work, kinda, but is not advised, as what you're doing is permanently altering ther magnetic gap, which is a crucial part of the permanent portion of the speaker, to save a replaceable part that has gone our of spec and will probably continue to do so. You're also going to get grit in the gap, which is a bad, bad thing.

DO NOT use super glue on a speaker. It dries brittle, so it will crack, and it degrades with heat and voice coils do get hot.

The best solution is to bite the bullet and replace the basket - you'll have a new speaker instead of a damaged used one with a kludged repair.

If the speaker is dead open, make sure that the problem is not a damaged tinsel lead-in wire between the speaker terminals and the cone. That CAN be replaced with no problem, using inexpensive material from any of a number of vendors. You'll need to be careful and use heat sink clamps to avoid having the solder wick into the wire, making it stiff. Look for "reconing supplies" on Google.

If you replace the tinsel lead, make sure that it has enough slack to allow for full cone excursion, but not so much that it can short against the frame or the other lead.
I get what you're saying John, and as always/most the time you're correct. I learned the hard way back when I was a kid, on the solder wicking. I'd like to hear from the OP, if he tried swapping the speaker wires, to see if it is the speaker. I've an old Trace Elliot Super Tramp Twin, 20 years ago it did this, ended up being an output module crapping.
EDIT= It wouldn't hurt for the OP to check those 3 allen bolts also.
Old 17th September 2020
  #19
Quote:
Originally Posted by Rick Dalton View Post
I get what you're saying John, and as always/most the time you're correct. I learned the hard way back when I was a kid, on the solder wicking. I'd like to hear from the OP, if he tried swapping the speaker wires, to see if it is the speaker. I've an old Trace Elliot Super Tramp Twin, 20 years ago it did this, ended up being an output module crapping.
EDIT= It wouldn't hurt for the OP to check those 3 allen bolts also.
I doubt the bolts would be a problem. Peavey puts a ridge around the magnet to insure proper alignment. The whole basket replacement process is pretty foolproof - the hardest part is cleaning the gap with tape. You just follow the instructions. IIRC they even give you the proper allen key.

I would also check the output of that module to make certain it's not passing DC, which would blow the speaker.
Old 17th September 2020
  #20
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Rick Dalton's Avatar
Quote:
Originally Posted by John Eppstein View Post
I doubt the bolts would be a problem. Peavey puts a ridge around the magnet to insure proper alignment. The whole basket replacement process is pretty foolproof - the hardest part is cleaning the gap with tape. You just follow the instructions. IIRC they even give you the proper allen key.

I would also check the output of that module to make certain it's not passing DC, which would blow the speaker.
i cant remember, seems I'd mentioned about checking for DC,,,? may have been another thread. The OP may have done, what seems the norm. needs help and never hear back. usually its the noobies. Just thought i throw the bolt part in.
Old 17th September 2020
  #21
Quote:
Originally Posted by Rick Dalton View Post
i cant remember, seems I'd mentioned about checking for DC,,,? may have been another thread. The OP may have done, what seems the norm. needs help and never hear back. usually its the noobies. Just thought i throw the bolt part in.
I don't know either, but it crossed my mind so I mentioned it. I don't check this forum (or the site) every day anymore. I actually prefer a couple sites where the guys are a lot more "senior" and more recording oriented.
Old 17th September 2020
  #22
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Quote:
Originally Posted by John Eppstein View Post
I don't know either, but it crossed my mind so I mentioned it. I don't check this forum (or the site) every day anymore.
i've not much to do, as I have to be around 24/7 to take care of my Mother. So this is the only game in town.
Old 17th September 2020
  #23
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ggrey's Avatar
 

Hi guys...OP here just checking in. The amp is at my drummers house and he went on vacation a few days ago so I will not have access to the amp until he gets back. I do appreciate your inputs and will reply back once I have tried all your suggestions...or at least the one(s) that arrive at the answer. Good suggestions and advice all !!
Old 1 week ago
  #24
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ggrey's Avatar
 

Ok OP here
I finally got access to the amp and here are my findings...

I switched wires so the left amp powered the right distorted speaker. No change. The speaker still distorted.

I laid the amp on its back and played through it for a while, hoping if something was loose, stuck in the speaker or cabinet it would shake out. No go.

Then I removed the 3 bolts and very gently lifted the magnet from the voice coil. There was no scraping and everything looked perfectly fine, except...

In the center of the magnet was a small round flat grey sponge like thingy that was barely hanging on and loose. Nothing I could do but remove it and when I did it crumbled to the touch.

I blew out the channel where the voice coil sits with an air compressor, carefully placed the magnet back over the coil, re bolted and attached the wires.

Flipped the amp over, removed the grill and gently pressed on the speaker cone equally with 5 fingers. No scraping or noise at all. Turned on the amp and the distortion remains.

Finally un hooked the distorted speaker, turned the amp back on and the distortion remains only lower and softer in volume

Remover the distorted speaker and ...no distortion.

Three of us inspected the speaker and could see nothing wrong, no tears, no splits nothing. So here we are, maybe I will run into someone who knows speakers and could fix what needs fixin for minimal $$.

I really appreciate all you sluts who chimed in to assist! Thank you from the bottom of my distorted heart.
Old 1 week ago
  #25
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Rick Dalton's Avatar
Quote:
Originally Posted by ggrey View Post
Finally un hooked the distorted speaker, turned the amp back on and the distortion remains only lower and softer in volume

Remover the distorted speaker and ...no distortion.
This above really doesn't add up....unless its a typo?

You unhooked the distorted speaker, turned the amp back on and the distortion remains only lower and softer in volume.
Old 1 week ago
  #26
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It's a stereo amp, duh! Having no speaker connected to one of the power amps likely would result in some (possibly softer) distortion as I'm pretty sure the Peavey Chorus used a shared power supply so even the "good" side would be affected.
Old 1 week ago
  #27
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Rick Dalton's Avatar
Quote:
Originally Posted by enorbet2 View Post
It's a stereo amp, duh! Having no speaker connected to one of the power amps likely would result in some (possibly softer) distortion as I'm pretty sure the Peavey Chorus used a shared power supply so even the "good" side would be affected.
You just had to put the "duh!" in there. for what reason? Other than being an what?
Look at your response, You throw doubt into what you're saying.
Also while you're at it, explain "Remover the distorted speaker and ...no distortion." If you can. duh!
Quote:
Originally Posted by ggrey View Post
Finally un hooked the distorted speaker, turned the amp back on and the distortion remains only lower and softer in volume

Remover the distorted speaker and ...no distortion.
Old 1 week ago
  #28
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enorbet2's Avatar
Quote:
Originally Posted by Rick Dalton View Post
You just had to put the "duh!" in there. for what reason? Other than being an what?
Look at your response, You throw doubt into what you're saying.
Also while you're at it, explain "Remover the distorted speaker and ...no distortion." If you can. duh!
Whoa Rick Dalton, if I'd meant to direct that at you as some sort of nasswhole jibe, I'd have quoted you or wrote your name. I don't know about you but I've made enough dumb mistakes in my life my forehead is dented

To be absolutely clear, while you were INcluded AND I didn't EXclude myself it was more directed and in facepalm fun at ggrey since he was first to mention it's stereo and ideally should have some load. Some SS amps will handle a no load condition but all of those, to my knowledge, have 1 PSU per Power section... not shared.

I've apparently added to my personal dent by missing altogether the sympathetic vibration situtaion resolved by pulling the speaker completely. Then again, I did think it was a given that speaker was blown..... I still missed the remark, so no worries we all have our Homer Simpson moments.
Old 1 week ago
  #29
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Rick Dalton's Avatar
Quote:
Originally Posted by enorbet2 View Post
Whoa Rick Dalton, if I'd meant to direct that at you as some sort of nasswhole jibe, I'd have quoted you or wrote your name. I don't know about you but I've made enough dumb mistakes in my life my forehead is dented

To be absolutely clear, while you were INcluded AND I didn't EXclude myself it was more directed and in facepalm fun at ggrey since he was first to mention it's stereo and ideally should have some load. Some SS amps will handle a no load condition but all of those, to my knowledge, have 1 PSU per Power section... not shared.

I've apparently added to my personal dent by missing altogether the sympathetic vibration situtaion resolved by pulling the speaker completely. Then again, I did think it was a given that speaker was blown..... I still missed the remark, so no worries we all have our Homer Simpson moments.
Sorry I jumped to conclusions. You know how GSz can get. So thanks for clearing that up.... You can kind of see, as you'd be the same if it felt like an insult to you intellect. I was just trying to unscramble what the OP was trying to convey. Sorry Sir.
Old 1 week ago
  #30
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ggrey's Avatar
 

Sorry guys ...

"Originally Posted by ggrey View Post
Finally un hooked the distorted speaker, turned the amp back on and the distortion remains only lower and softer in volume

Remover the distorted speaker and ...no distortion."

Should read...

Finally pulled the wires off the distorted speaker, turned the amp back on and the left distorted speaker is still buzzing with distortion only lower and softer in volume.

I then unscrewed and removed the distorted speaker from the cabinet and the amp plays fine ( of course now there is only 1 speaker in a 2 speaker cabinet) with no distortion.
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