EV RE-20 Low output

[kooma]

Anyone had similiar?
I get sound, but it's REALLY low and no bass.
capsule "looks" good, all solders/connections looks ok.
Measured dcr between pins 2&3 and got something like 25-29ohm depending on lowcut filter.

 

[PRR]

> REALLY low and no bass.

On a dynamic (speaker or microphone), that means the voice coil is bound-up in the gap. You can't get the big motions of bass. Some small treble motion happens through coil elasticity.

On the classic E-Vs, I would suspect it has been dropped and the magnet structure shifted.

At one time, E-V was very good about repairing (re-gutting) these types of failures, no problem. However the RE-20's time is way in the past. Even if they could afford to fix ancient microphones, they may not have the materials at hand any more.

 

[kooma]

> REALLY low and no bass.

On a dynamic (speaker or microphone), that means the voice coil is bound-up in the gap. You can't get the big motions of bass. Some small treble motion happens through coil elasticity.

On the classic E-Vs, I would suspect it has been dropped and the magnet structure shifted.

At one time, E-V was very good about repairing (re-gutting) these types of failures, no problem. However the RE-20's time is way in the past. Even if they could afford to fix ancient microphones, they may not have the materials at hand any more.

ok, thanks for the info!

 

[RuudNL]

As far as I know the RE20 is still in production.

 

[MicDaddy]

#1 suspect, debris on the diaphragm... check the diaphragm for ferrous bits, easily removed.

#2 suspect, glue creep...  the adhesive(s) used to glue down the diaphragm can creep up the diaphragm and inhibit its bounce range.

#3 suspect, blunt force trauma like PRR said.  They can take a beating but they don't make them how they used to.  There is nothing other than glues (with exception to magnetic forces) holding the magnet structure together.  If the faceplate shifts, it pinches the coil into the magnet.

#4 suspect, voice coil starting to come apart.  They can unravel, though usually they still have good output but with a boingy spingy sound on transients.

I've seen the passive circuits go wonky but if the transformer is still ok it should be putting out healthy level, just might sound offensive in the essshy frequencies.

Check the diaphragm first... 0.035" hex to get in the headbasket.  I'm betting it's frozen shut with foam gone to goo and ferrous bits.

They still make these mics, though the insides are quite a bit different and have changed a lot over the decades.

I can repair just about anything inside this mic including winding new voice coils and rewinding the transformers.

 

[kooma]

Thank you all for tips.
I took few photos, capsule doesnt look dirty, foam on the grille and around capsule were ok,
but the bottom foam(under tha capsule/above transformer) was all mushy..

 

[kooma]

capsule closeup

 

[kooma]

capsule without that plastic "thing" is that foam really suppose to be there? and what's it's funtion? dampen something?
I tested mic without the foam, as it fell off taking these picture and output was lot healtier; but dunno was it normal, this is the first time I hear this mic

 

[kooma]

foam fell off

 

[kooma]

closeup

 

[kooma]

sorry for spamming pics

another thing is that I found schemo online:
https://www.gearslutz.com/board/attachments/geekslutz-forum/324380d1357614872-temperamental-ev-re20-late-re20-circuit.jpg
and this mic seems to be earlier model, this is missing those caps
and transformer has more wires red,blk,yel and grn,blue,blk

 

[MicDaddy]

That capsule was made 34th week of '98

The circuit likely has a transformer, one inductor and one cap, there will be another inductor for the bass roll off.

The schematic you linked to was for the version after yours.

Lol at that foam....  :  get it out of there.

If you hold the capsule from the bottom black circle, and wiggle it back and forth do you hear a clicking or see that little black button under the diaphragm moving?  Clicky clicky clicky.....  if that dome is off center it needs rebuilt.

Even with the black button coming free, if you're only using it for voice... it is possible to wiggle the pole piece into position where the mic "sounds good enough" on voice, and then just don't ever move it.  Any high SPL will cause funny distortion.

Yes get that foam off of the diaphragm, likely a previous owner noticed distortion and put that there to damp it.

 

[kooma]

Thanks! That foam really felt odd, but as never seen this mic before, so I thought it must be some clever...well something

Yes, that black button is moving freely as I tap the side of the mic or shake it!
so that foam must be put in there to keep that button center!(?)

F*ck.. so new capsule or rebuilt?

 

[MicDaddy]

The foam is preventing all of your excursion = giant debris  8)

You should get some bottom end back with that foam gone. 

You can find new capsules here http://www.fullcompass.com/product/471335.html

If you want to talk about trading your capsule + $99  for one I've rebuilt you can email me.

 

[zebra50]

Ben's rebuilt capsules are excellent BTW. I have used a few and there is no measurable difference between these and the factory-fresh capsules.

:thumb:

 

[kooma]

ok, Thank you all for info!
sent Ben e-mail.

 

[Bomper]

Hey, sorry to hijack this topic. I have a RE20 that I bought second hand. The mic sounds ok, i think (haven't owned one previously), but the whole capsule is able to move around in the mic housing because the foam, that normally surrounds the capsule and prevents it from ticking against the housing, has deteriorated over time. I think I see that foam in the first pic that kooma posted. Can I replace that foam with something new that would hold the capsule in place better?

Thanks in advance, Thomas

 

[kooma]

Hey, sorry to hijack this topic. I have a RE20 that I bought second hand. The mic sounds ok, i think (haven't owned one previously), but the whole capsule is able to move around in the mic housing because the foam, that normally surrounds the capsule and prevents it from ticking against the housing, has deteriorated over time. I think I see that foam in the first pic that kooma posted. Can I replace that foam with something new that would hold the capsule in place better?

Thanks in advance, Thomas

those foams seem to available from http://www.fullcompass.com/product/478061.html

 

[totoxraymond]

Hi,

Foam is quite easy to replace. There are several tutorials for this on the net. You will certainly need to replace the 2 foams. One is around the capsule, the other at the top end of it.

I even ordered the parts at my local microphone dealer and got them for 20€

I found this topic interesting since mine has the same problem since some time. I'll check it when i'll get time for this.

Thomas

 

[Bomper]

I'm checking to get the parts through Bosch because I'm in Europe. FullCompass doens't really deliver to Europe. Allthough I was able to ask for a quote from them to send the parts to Europe. Anybody have any experience with parts from FullCompass to Europe? They do have some nice replacement parts...

Regards, Thomas