Plate reverb driver repair - unknown maker

[dmp]

This is a driver for an old (20+ yrs) plate reverb. The plunger has a thin coil of wire (like a voice coil) and it sits in a magnet. Over the years the wires have broken repeatably, and to repair, the wires has been unwound. At this point it is not repairable. The current plan is to try to rewind it. Any other suggestions? Replacement?

The plate is 40" x 80" with a red frame. Any ideas on the maker?

 

[dmp]

Back of the magnet

 

[glorymorris]

Looks just like the ones used in the Echoplate. Could be from an EMT. Winding that thing is going to be a real bitch though.

 

[madswitcher]

It might be possible to get a speaker repair outfit to do a rewind for you as it seems to resemble a speaker voice coil.  If you are in the UK give Wembly Loudspeakers a call - usually a very helpful bunch

Cheers

Mike

 

[SSLtech]

..I'm pretty sure that Madison, Wisconsin is a pretty long way from Wembley... 

Most speaker repair places will only recone or use factory-supplied parts, I doubt that many (if any) do much coil-rewinding... but they are probably the people to start by asking.

 

[dmp]

Looks just like the ones used in the Echoplate. Could be from an EMT.

Probably not either of those - it could be a custom job. The ecoplate I've seen is similar, but the drivers are different. This one is massive in comparison. A very heavy magnet.
It is also a steel plate, so it is more like an EMT.

 

[QUEEF BAG]

another vote for a speaker repair house.

i had a toasted coil on an echo plate driver, took it to the speaker re-cone shop and asked if there was any way...

his only question was "ya want one 4 ohms or 8 ohms?".

 

[Bill Wilson]

I believe it is an Audicon plate that was sold by Audio Consultants, Nashville; I was service manager in the mid 70's before opening my own sales & service co. Audio Consultants was the MCI dealer for the southeast & Texas. I had run console checkout at the MCI factory in Ft. Lauderdale a few years earlier & became friendly w MCi's sales mgr. Claude Hill, who established A. Consultants.

Gene Lawson (Lawson Microphones) had the plate design but lacked a marketing organization & funding. A. Consultants sold the plates & paid Gene for the units.

With respect to the driver, he selected a speaker that had the desired magnet assembly. Saved the voice coil, & widened the magnetic gap to prevent a rubbing voice coil; the voice coil was fastened to the plate & the magnet assy. was mounted on an lauminum plate & fastened to two upright 1/2" steel angle pieces welded to the top & bottom of the frame. The voice coil should be 8 ohms.

Sorry about the mistaken identification as I had not looked at the picture of the rear of the driver. Anyway you now know how the Audicon plate driver was made.

 

[chet.d]

Giving this a nudge for any appreciated insights.

I have an ecoplate 2 that has an issue in that the speaker (input) to the plate has been determined to clearly "break up too early" by myself & a tech here.  As a result, the returns have to be pushed to hard and results in too much noise. 
Otherwise, the amp was recapped and attended to by JW so the amp seems to check out fine.

We discovered that the voice coil windings are slightly undone in a spot or two. The tech believes it's likely the issue and he believes that a reglue of the windings should be possible as they're only slightly separated in two spots.

So I'll soon find out. He may be by tomorrow for the attempt.
Otherwise I may need to seek out a replacement which is so far,  tough to find info on what might be appropriate given the plates design by JC.

Wanted to mention FWIW and in case anyones had a similar issue,  or suggestions.
Thanks.

 

[Bill Wilson]

It sounds as though the loose wire on the voice coil is likely rubbing on the magnet structure; in other words it is a rubbing voice coil. The v.c. needs to be rewound. It should be an 8 ohm voice coil.

 

[chet.d]

It sounds as though the loose wire on the voice coil is likely rubbing on the magnet structure; in other words it is a rubbing voice coil. The v.c. needs to be rewound. It should be an 8 ohm voice coil.

Thanks Bill. 
The tech worked on the VC today with a re-glueing of the windings and reassembled.  We were very careful to position the driver back on to make sure the VC is Not rubbing on the magnet structure.  It move smoothly back & forth inside the magnet.

...Unfortunately, the input break up sound (hairiness) ensues and it does not seem to be appreciably better.

Although the amp was  worked on a few months ago by JW  (changed some of the drive/recovery EQ caps to compensate for the greater low end the discs have.  +  opamp and resistor changes to optimize the noise floor)

…the tech suggested we try to use another small amp to drive the speaker and rule out that there may be something going on there.   

So the saga continues.  It's remarkable to me it's been such a PIA as there's really not much to the whole design but so it be.

 

[Whoops]

…the tech suggested we try to use another small amp to drive the speaker and rule out that there may be something going on there. 

I think thats a good idea.

Also are you sure the coil doesn't need to be re-wound instead of just glued?

 

[emrr]

I suppose there could be an intermittent factor in the winding, almost like a spark gap, which passes enough to make 'hairy audio'. 

I've seen something similar with output transformers passing DC in which a certain amount of current made background noise, but it you ran audio with no DC current, it was fine.  The particular transformer later went fully open circuit. 

 

[chet.d]

The tech knows quite a bit about speakers/VC's  and believes that if any distortion ensues the re-glue,  it's not the VC.

It seems the amp should be checked out.  Hope to get that done in the next few days.

I'd honestly love to hear of any others experiences with the ecoplate 2 and its innate sound if there's anyone out there.
It's a tough one to generally assess & have an idea of what it "should" sound like.  I also may not have it tuned well.
Hope to report back soon & thanks for the thoughts.

 

[dmp]

I have an ecoplate at my studio space and I usually drive it with a monitor speaker hanging about 1.5' away. The mounted VC works fine but I rarely use it since the speaker sounds really great and I don't want someone to fry it.
It sounds wonderful. Pretty much everyone that comes in and hears it is blow away.

I would suggest trying yours out with a speaker and make sure you can get good results (you should be able to). If you are driving the plate too much (whatever the sound source) you will get something that doesn't sound good. If you are driving it too low you will have too much noise on the return.  Mine has a sweet spot that sounds great and has a noise level you can live with.
If you are used to verb plugins that have no noise, you might be trying to get something that isn't possible in the real world, by driving it too hard to reduce the noise.

I have compared the mounted VC to the speaker and the noticeable difference is in the low end, which I don't generally want much of anyway.
If you want to send me something I could run it through for you to hear.

 

[radardoug]

Is that 1.5 inches or feet away?

 

[dmp]

Feet

 

[chet.d]

Feet

Wow really?  seems like a far distance from the plate.

Kind of you to offer running a file through yours. I'd be glad to take you up on that.

It continues to seem clear that the input gets a bit distorted at low input levels.  I'm not bothered by the returns noise,  just trying to optimize this thing before setting & forgetting.  So far, the amp seems to be checking out.

The tuning does however have me thinking its influence on its sound is significant and w/o  the JC tuning gauge,  it seems the tuning sweet spot can be elusive thus far.

 

[dmp]

Wow really?  seems like a far distance from the plate.

Kind of you to offer running a file through yours. I'd be glad to take you up on that.

You can actually just drive the plate with music in the room too. Drums for instance can be in the same room as the plate.

Email me by clicking on my user name if you want to run a file.

 

[emrr]

You can actually just drive the plate with music in the room too. Drums for instance can be in the same room as the plate.

True, my Ecoplate I is in the live room next to drum position, You could definitely print live from that.