[Neutrino]

Dear all,

my first post here after enjoying the wisdom gathered in this forum for some time now...

I got an Electrovoice PL20 microphone from eBay which to my knowledge is identical to the better known RE20 except for the color.
When I first tested it, I was disappointed by the nasal tone it delivers, so I did a side by side comparison with an almost new RE20. Both microphones recorded simultaneously, i.e. it is the same take, same distance and both high-pass filters were deactivated. The differences are unmistakable. Please listen yourself:

RE20 (intact):
https://www.dropbox.com/s/klo37cqhb7pemqw/RE_20_Test.mp3?dl=0

PL20 (is it broken?):
https://www.dropbox.com/s/ptwg0qui8smzmuo/PL_20_Test.mp3?dl=0

Forgive my crappy singing 

Is the PL20 supposed to sound like that or is it broken? Any suggestions are appreciated.

Best,
Waldemar

[klaus]

"Broken" may be too strong of a word.
If your two samples are truly representative of the sound of the mics (always a big "if" in my experience), the PL
seems a bit more mid-ranged pinched, but with excellent high frequencies, yet a bit tight in the bass. Put another way, the RE seems smoother overall.

I would start by checking output impedances of both mics (see wiring diagram below) and, if the strapping of the RE is different, make it the same for the PL. 

I have found that, against all logic, in most situations the 500Ω strapping is beefiest and best for RE20, but that may not apply in your situation, as I don't know how your specific preamp's input impedance communicates with these mics.

[Neutrino]

Klaus, thank you for the quick reply. Here are a few more details:

- I recorded both mics through my Apollo preamps which are very clean and have a rather high input impedance (5.4 K Ohms). I use these preamps constantly and never had any trouble.
- No other hardware or plugins were used in the signal path
- The "jumper" for the output impedance selection of the PL20 is set to 150 Ohms (I checked).
- The RE20 is new and hasn't been modified, so the output impedance is the default 150 Ohms as well (I'd like to avoid opening it if possible
since it is new and the XLR jack is still sealed)
- When I measure the DC resistance between Pin 2 and Pin3, I obtain the following reading:
  RE20: 32.5 Ohms
  PL20: 25.3 Ohms

As far as the sound is the PL20 is concerned maybe my sample did not expose it extremely enough, but it can REALLY be annoying in the 3k region, while the RE20 is very smooth as we all know it from radio 

[klaus]

Set the PL20 to 250Ω, then to 500Ω and report back on the differences.

If the pinched midrange remains in all three settings, the problem may be capsule related. Replacing the capsule unit is a major repair cost.

[Neutrino]

I understand, you are trying to exclude the transformer as a potential cause?

Right now I'm only looking for a confirmation that SOMETHING is wrong with this mic. If that is the case, I will ask for a refund as the mic was sold as fully functioning. To do that, I shouldn't touch the mic with the soldering iron for now.

[klaus]

I neglected to point out something important earlier, because I read your OP sloppily:

Your sound files cannot determine whether this particular mic is defective. The reason: no credible third party observed your test setup which the sound files were based on. Only EV can make an objective determination whether what you heard indicates the mic is out of spec.
I would contact EV directly: Phone +1-800-289-0096, E-mail TECHNICAL.SUPPORT@US.BOSCH.COM

Additionally, my experience with sellers is one of two: they either are gracious and won't drag you through the hassle of filing a claim, regardless whether you are right or wrong, or they will fight you. If the latter is in the wings, I would make damn sure to submit more than third-party opinions based on sound files. Providing independent third-party objective confirmation of your suspicion is the way to go with eBay.

[Neutrino]

Thanks for your experience, Klaus.
Yes, I already tried to contact Electrovoice earlier. But they could only offer me to send in the mic for repair which will immediately cost a significant amount.

Probably what I will do is to bring the mic to a workshop at the next large music store. It will cost a small amount to have them  analyzing the mic and making an estimate for the repair job, but then having it black an white I should be on the safe side.

[panman]

The most likely fault with your PL20 are the plastic-foam parts  (#15 and #17 in the pic Klaus posted). The plastic-foam has deteriorated without any exceptions in mics  as old as all PL20's are. Those parts need to be replaced and eventually the diaphragm needs to be cleaned of the foam sticking to it.

This all is not just a simple matter and need to be done by an expert with experience with these mics. For the diagnosis however the mic needs to be opened to be sure. It is possible, that the parts have been replaced, but the diaphragm was not cleaned or some other damage was done.

Although I hear unwanted high-mid frequencies in your PL20 sample, I would not conclude much just because of that. Make sure the people at the music store are experienced with these mics (PL20, RE20), or otherwise look for somebody else to do that. By the way, those parts #15 and #17 are still available from EV.

[Neutrino]

The foam in the PL20 is intact. Actually, it looks rather new. Probably it has been replaced, as you say, but damaged or not cleaned properly while doing so.
But if that theory is correct, the technicians at the shop will not notice any abnormality if they only do electrical measurements of the circuit. will they?

[klaus]

I am confused now: You don't want to open the mic, but you think you can get someone to test the mic beyond what you were able to do without opening it up?

And you don't want to send the mic to EV, which would be the place to get a definitive answer.

This to me seems like a lot of complicated moves for a simple purchase. 

Is the seller cooperating with you on this? Have you had clear communications with him about your concerns? 
Why not look for a different mic and try to undo the purchase?

[Kai]

This microphone does not work like you expect it to do.
In cases like this I usually ask the seller for a reasonable refund, let's say 50%, if I think I can fix it by myself.

Otherwise, I would arrange with the seller to send the microphone back for full refund.
Spending extra money on this does not make sense, except if it were a real bargain.

If the mic is contaminated with deteriorated foam (even the variable D element, the tube behind the capsule), that can be cleaned, and I would give it a shot.
There is not much more you can fix, maybe check the filter cap .56uF.

[Neutrino]

OK, let me clarify a few points:

- I send these audio samples to the seller last week. He claims that he doesn't hear a difference, but he was probably listening on his laptop speakers. He said he has access to high quality studio monitors at work and would get back to me once he has listened on them. I haven't heard anything from him yet. But my feeling tells me that it will not be easy to convince him and I'm trying to anticipate what my next step should be.

- Of course, my objective is to send back the mic for a refund. But for that I need to prove that the mic is not fully functioning. That is why I think sending it to an independent microphone technician who provides the attestation that the mic is defective might be a good idea (actually that is what eBay proposed to do). Once I know a good address, I will ask the seller for his agreement on the procedure.

- I don't want to make changes to the microphone myself because then the seller has good reason to claim that I did cause the damage myself.

- I was in contact with Electrovoice/Bosch Germany. I've been told that they cannot provide the kind of attestation I am looking for. If I send the mic to them, they will repair it and send it back. This will not be cheap and I found it somewhat strange, but that's what I have been told.

- If someone can recommend a technician in Germany who would create the kind of attestation I am looking for, please propose.

Hope it clears things up a bit 

[Dan Popp]

- Of course, my objective is to send back the mic for a refund. But for that I need to prove that the mic is not fully functioning.

I'm not conversant on the official rules of eBay, but in my opinion the seller should refund your money if you're not happy with it, period.  Aside from personal integrity and ethics, he wants to avoid a negative seller rating from you. 

[Neutrino]

I'm not conversant on the official rules of eBay, but in my opinion the seller should refund your money if you're not happy with it, period.  Aside from personal integrity and ethics, he wants to avoid a negative seller rating from you.

As a private seller you can exclude any warranty and then you are not obliged to take the item back just because the buyer is not happy with it. But if the item is "not as described", which is the case here, even a private seller has to take the item back for a refund. But the buyer has to prove this.

[Kai]

- If someone can recommend a technician in Germany who would create the kind of attestation I am looking for, please propose

I don't know if this hurts the rules of this forum, but I could help you out by measuring and comparing the microphone to two other RE20 I have, plus the one you got.
I would measure acoustic frequency response, and impedance vs frequency, to exclude electrical defects.
I'd only ask for small fee, I don't want to make a business out of this.
I am located in Germany. P.m. me if you are interested.