Recone for D131 16 ohm needed

[horseshead]

I have a D131 that is buzzing again. The first time it buzzed I removed it from the amp's baffle board, let it sit for a week then reinstalled it carefully so as not to over tighten the screws. This worked for a while but it's buzzing agian.

Is there anyone that can recone it. I can't sell it like this. Thank you,
Rick

[Thom]

You've probably already checked, but if the aluminum cap gets partially loose it can make a hell of a lot of noise. I've gotten a couple over the years for almost nothing that had nothing else wrong. Probably not your problem but couldn't hurt to check if you haven't already.

[horseshead]

I'll check. Is there any special way of checking? If it is loose, what is used to tighten it up - a glue of some sort?

[Thom]

Try to rattle it with your fingers. If it's loose you will know it. As far as glue, I'm sure there is a proper glue and I'm sure I didn't use it so Ill let someone else answer. I sure hope that's your problem because it's a real easy fix. Every thing else isn't so easy.

[horseshead]

Tom,
I tried to rattle the dust cap and it's not loose. I tightened the screws and the buzzing just got worse. Who recones these speakers?
Rick

[Zilch]

http://www.jblproservice.com/service/index.html

[Robh3606]

Well this is a reach but older D-130/131's had very tight voice coil tolerances and if your baffle board is a bit warped that could be it. You check the baffle board at all??? You never know, if it goes away off the baffle board I think it's worth a shot to take a look,

Rob:)

[boputnam]

I have a D131 that is buzzing again. The first time it buzzed I removed it from the amp's baffle board, let it sit for a week then reinstalled it carefully so as not to over tighten the screws. This worked for a while but it's buzzing agian. Describe the buzzing - is it mechanical from the baffle board, or from the voice coil (can you tell...?)


Try to rattle it with your fingers. Do not do this. Bad idea and could result in worse or new damage to the voice coil.


Who recones these speakers?There are members here who do - I have not checked if the kits are available (I doubt it... :( ). edgewound does this work, he's very reliable.

Take the woof off the baffle, lay it on it's motor and run a frequency sweep at low voltage drive. Listen carefully, and patiently for buzzing to occur, frequency specific. Often, older drivers like this will get into trouble - maybe a warped voice coil from over-heating / over-driving; physical damage from partially jumping the gap; sagging spider - dunno.

The voice coils of these are quite shallow (as compared to later / currrent designs) and prone to frustrations...

[Thom]

This is old enough that it's probably resolved but if all you are looking for is a cap partially unglued I really don't understand your dire warning. I didn't suggest that this was the most likely, only that it could be and if it was it would be dirt cheap. If the noise is a slapping dome, I've seen a few, you can tell quickly with your fingers, and not by touching the center of the dome. This isn't a challenge or any silly thing like that I just didn't understand "the earth will open and swallow you" bit. It's not like I told him to try to figure which direction the coil was off center from the magnet and then get a 2x4 and hit the pot the direction the coil was. And that's what makes alnico better than ceramic. Actually I was just curious what you thought I was telling him to do. It sounds like he had already done it when you posted.

[horseshead]

Describe the buzzing - is it mechanical from the baffle board, or from the voice coil (can you tell...?)


Take the woof off the baffle, lay it on it's motor and run a frequency sweep at low voltage drive. Listen carefully, and patiently for buzzing to occur, frequency specific. Often, older drivers like this will get into trouble - maybe a warped voice coil from over-heating / over-driving; physical damage from partially jumping the gap; sagging spider - dunno.

The voice coils of these are quite shallow (as compared to later / currrent designs) and prone to frustrations...

Would I not need to find a signal generator in order to perform a frequency sweep? I don't own one. Also, give me a number of what you mean by a low voltage drive.

[Thom]

This isn't anything a person would normally have to do but what you said makes me ask. Does loosening and tightening various mounting screws make any difference? In the absence of an oscillator play something it likes to buss to. I'm thinking like a warped brake drum or rotor but I have no way of knowing if you can relate to that or not. Of course if you are selling it it might be irrelevant. You might find a position maybe even with a small shim where you could play it and be happy but selling it. I have no advice on selling it. You probably cant re-cone it and sell it and come out on top so I guess you could sell it with that info someone might want it like that, I have no idea. It would be unusual but not unheard of if you could make it play by tightening it a certain way. More common would be if it played OK till it warmed up. I only even suggested that because you said it got worse as you tightened it.
I think there are tones available on the Internet and you could burn a Cd. Try the sight at the address below. You should be able to get what ever tone you want. then burn it to a Cd then play the Cd through the speaker
Good luck
http://www.eminent-tech.com/music/multimediatest.html

[horseshead]

I think there are tones available on the Internet and you could burn a Cd. Try the sight at the address below. You should be able to get what ever tone you want. then burn it to a Cd then play the Cd through the speaker
Good luck
http://www.eminent-tech.com/music/multimediatest.html

Thom,

I followed you up to the part where you remove the speaker from the amplifier and baffle board and lay it down on it's motor side. How could I play the CD of the tones through the D131 speaker? Would I hook my D131 up to my stereo? Even if I did, it's a 16 ohm impedence speaker and my stereo's speaker output jacks are for 8 ohm impedence speakers.

Hoping 2007 provides all your heart's desires,

Rick

[Guy in WNY]

Hi,
I ran the test tones just now. My 14 yo son yelled at me to turn it off when I got up to the 15,000 tone! It was hurting his ears - I could hear it, but no pain was involved. I guess those 2402's do lend a bit to the high end.
50 and 30 cycles both came through clear. Putting the subharmonic synth on the 30 cycle note just doubled it down and it sounded as if there were 2 distinct notes, which there were, but quite a bit "slappy".
The phase seemed OK.
I need to try out some free downloads and run a few sweeps. Change things around and get a good, steady, repeatable baseline setup and then start making changes. Lots of work to do.
Sounds like fun to me!

[glen]

... it's a 16 ohm impedence speaker and my stereo's speaker output jacks are for 8 ohm impedence speakers.
It's OK to run an amp with speakers of a higher impedance than specified (16 instead of 8). It's only when running amp with an impedance that is too low that it hurts: too little impedance --> too much current --> amp overheats --> magic smoke escapes from amp.

[horseshead]

It's OK to run an amp with speakers of a higher impedance than specified (16 instead of 8). It's only when running amp with an impedance that is too low that it hurts: too little impedance --> too much current --> amp overheats --> magic smoke escapes from amp.

Let's talk about my guitar amp then as well as my stereo amp. I have a fender quad reverb with 4 - 16 ohm taps. If I tried to connect 4 - 8 ohm speakers to it instead of 4 - 16 ohm speakers wouldn't magic smoke escape from IT too?

[johnaec]

Let's talk about my guitar amp then as well as my stereo amp. I have a fender quad reverb with 4 - 16 ohm taps. If I tried to connect 4 - 8 ohm speakers to it instead of 4 - 16 ohm speakers wouldn't magic smoke escape from IT too?If you have four 8-ohm speakers you'd want to hook them up series-parallel, (hook 2 speakers up in series so you have 2 sets of 2 in series, then parallel these 2 sets), and you'll end up with a total impedence of 8 ohms.

Edit - now I'm confused - I thought you meant you wanted to hook [quantity] four 8-ohms speakers to one amp - likewise, when you say "4 - 16 ohm taps", do you mean [quantity] 4 taps, or different taps, from 4 ohms to 16 ohms?

John

[glen]

Let's talk about my guitar amp then as well as my stereo amp. I have a fender quad reverb with 4 - 16 ohm taps. If I tried to connect 4 - 8 ohm speakers to it instead of 4 - 16 ohm speakers wouldn't magic smoke escape from IT too?

It's a definite possibility. Most tube amp outputs have switchable taps to handle 4, 8 or 16 ohm speaker system loads so they can work with a variety of speaker system loads. If you change the speakers to a different impedance model you should change the output impedance tap so it matches the new speaker system load to avoid straining the amp.

[horseshead]

If you have four 8-ohm speakers you'd want to hook them up series-parallel, (hook 2 speakers up in series so you have 2 sets of 2 in series, then parallel these 2 sets), and you'll end up with a total impedence of 8 ohms.

Edit - now I'm confused - I thought you meant you wanted to hook [quantity] four 8-ohms speakers to one amp - likewise, when you say "4 - 16 ohm taps", do you mean [quantity] 4 taps, or different taps, from 4 ohms to 16 ohms?

John

I'm talking about my guitar amp. It's output transformer has 4 taps, in other words I'm saying 4 wire connections, each connecting to a different speaker. Each speaker is supposed to be 16 ohms and the total output transformer is supposed to see 4 ohms.