Help w/speaker wire connection pos vs. neg

Newbie-Doo said:
Here is my Peavey Combo 300 Bass amp that I picked it up last night. If you can believe it, I got it for $30 plus tax. I found this same model for sale on Ebay for almost $700!


I needed something loud enough to play with a band but I just don't have the money for it. I asked the Lord if he could help me find something and he has provided!

It was absolutely filthy and all the screws were missing. The head was bobbing around loose and falling out. The power light came on but it wouldn't produce any sound at all. Not even buzzing or hum.

I took it home, took it apart, found a broken connection and soldered it, then I scrubbed and cleaned and added about $7 worth of screws to hold it together.

For about $40 total I have an awesome amp and I'm ready to rock with a band! Woohoo!

Thanks again for your help! :D:D:D
D
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Really glad it worked out for you dude. You had the right answer to your problem on page one so forgive me for the subsequent train wreck.;)

There are a lot of very knowledgeable helpful folks round here in the guitar and bass board and it isn't hard to spot them. Unfortunately we are having to deal with an infestation of "stupid" recently and your thread got caught in the vapour spray.

Once again. I'm glad it worked out for you and stick around we are a decent bunch really.;)

Enjoy the amp.
 
Victory Pete said:
Good for you! I just retired one of those, we used it for years. It is currently for sale here. It was replaced with an Ampeg SVT Classic with 8-10 cab. Good luck, it is a workhorse.
VP
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Thanks man!

The SVT/8x10 is in my opinion THE greatest bass amp and cab combo of all time. Pure tonal bliss.

Through my years of watching bands, there has only been a couple of times the bass player sounded so good I wanted to know what he was playing. Each time it was an SVT/8x10.
 
muttley600 said:
Really glad it worked out for you dude. You had the right answer to your problem on page one so forgive me for the subsequent train wreck.;)

There are a lot of very knowledgeable helpful folks round here in the guitar and bass board and it isn't hard to spot them. Unfortunately we are having to deal with an infestation of "stupid" recently and your thread got caught in the vapour spray.

Once again. I'm glad it worked out for you and stick around we are a decent bunch really.;)

Enjoy the amp.
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Thank you sir, I definitely will. :)
 
arcaxis said:
DC is how I check a speakers polarity where there's no marking. :)
A quick tap with a 1.5v battery. If the cone moves outward I consider where I put the battery positive to be the (+) of the speaker terminal. Don't know this is a standard way of doing it, but I picked this up somewhere years ago.

Hmm, I was typing when 2 posts appeared......
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yeah but you're not putting the kinda current an amp puts out if it goes bad and starts putting DC into the speaker.
Older Crowns used to do it all the time.
 
Victory Pete said:
His method is common, I have done that myself.
VP
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so what?
I use the exact same method as does absolutely anyone that works on speakers.
I used to do recones BTW.
What I said was that when an amp has an output go bad and starts pumping DC into a driver ...... it smokes the driver .... and I said that older Crown power amps (DC-300 especially) used to do it all the time ....... doesn't have jack shit to do with sticking a very low current battery on a speaker to check it out or look for polarity. and I didn't say jack shit about batteries.

I was very clear ...... did you used to use a malfunctioning power amp to check your speakers?
If not, then your comment has absolutely nothing whatsoever to do with what I said.
And my comment, which you quoted! very specifically said I was talking about the high DC current you'd get out of a power amp going bad.
Did you see a single post by me concerning using a battery? Is there a single post about warning NOT to use a battery?
Isn't there a comment about batteries being fine but I was talking about power amps and have specifically said power amps every time?








Good lord you're a stupid fuck.
 
Lt. Bob said:
so what?
I use the exact same method as does absolutely anyone that works on speakers.
I used to do recones BTW.
What I said whas that when an amp has an output go bad and starts pumping DC into a driver ...... it smokes the driver ....... doesn't have jack shit to do with sticking a very low current battery on a speaker to check it out or look for polarity. and I didn't say jack shit about batteries.
I was very clear ...... did you used to use a malfunctioning power amp to check you speakers?
If not, then your comment has absolutely nothing whatsoever to do with what I said.
And my comment, which you quoted! very specifically said I was talking about the high DC current you'd get out of a power amp.
Did you see a single post by me concerning using a battery? Is there a single post about warning NOT to use a battery?
Is there a comment about batteries being fine but I was talking about power amps and have specifically said power amps every time?








Good lord you're a stupid fuck.
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All that is being pointed out is that the polarity can easilly be checked. Calm down.
VP
 
Okay, I now have a personal theory about why the old JBL speakers had negative polarity. Here goes:

On the old JBL speakers, there was very little voice coil overhang; i.e., the voice coil height was basically identical to the gap length. I had speakers come into the repair department that actually had the voice coil popped out of the gap. It was a rare occurrence, but I saw several examples of that during my days at JBL.

So, my theory is that good old Jim Lansing understood that a loud positive pop coming through an amp could push the speaker cone forward, clean out of the gap, while that same pop to a negative polarity speaker would slam the coil back into the basket, but that negative slam would cause less damage to the speaker than an outgoing pop would.

You'd hit the voice coil former to cone glue joint, and that would absorb some of the shock.

In addition, on horn-loaded drivers, the voice coil has to be sucked into the gap to produce a positive-going signal into the horn. That requires an inward-pulling signal to generate a positive output into the horn.

Anyway, that's my personal theory as to why the original JBL speakers had reverse polarity. In all the years I spent at JBL, I never thought to ask anybody why we did it that way. I'm sure George Martin or Howard Wieser probably knew the real reason.
 
Harvey Gerst said:
Okay, I now have a personal theory about why the old JBL speakers had negative polarity. Here goes:

On the old JBL speakers, there was very little voice coil overhang; i.e., the voice coil height was basically identical to the gap length. I had speakers come into the repair department that actually had the voice coil popped out of the gap. It was a rare occurrence, but I saw several examples of that during my days at JBL.

So, my theory is that good old Jim Lansing understood that a loud positive pop coming through an amp could push the speaker cone forward, clean out of the gap, while that same pop to a negative polarity speaker would slam the coil back into the basket, but that negative slam would cause less damage to the speaker than an outgoing pop would.

You'd hit the voice coil former to cone glue joint, and that would absorb some of the shock.

In addition, on horn-loaded drivers, the voice coil has to be sucked into the gap to produce a positive-going signal into the horn. That requires an inward-pulling signal to generate a positive output into the horn.

Anyway, that's my personal theory as to why the original JBL speakers had reverse polarity. In all the years I spent at JBL, I never thought to ask anybody why we did it that way. I'm sure George Martin or Howard Wieser probably knew the real reason.
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That is interesting.
VP
 
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