need a good low-z/high-z adapter

[harryh]

Hey guys,

 

I have a mandolin pickup that is really a dynamic mic element. It has an XLR out that is great for connecting to an XLR mic input on my MixWiz, etc.

Here's a link to a photo of one:

http://www.amazon.com/Schertler-DYN-M-for-Mandolin/dp/B001T9NUMQ

 

Balanced output, low impedance, sounds nice! Every now and then, though, I need to plug it into an amp, DI, or DI/preamp that doesn't have an XLR input.

 

So, I rummaged through my equipment shelves and found an old adapter that I bought 20 years ago from Radio Shack. Seems like it works okay. It looks like this:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=242-4776

 

 

So, I have a nice mando, a nice pickup, a nice mixer, nice speaks, etc. All of this is part of the same chain as my 'parts is parts' Radio Shack adapter.

 

It occurred to me that some adapters might be 'better' than others, or certainly better than my 20 year old Shack'dapter!

 

Just wondered if anybody here had an opinion, or a suggestion on a particular brand of adapter to buy.

 

Thanks, Harry

[twostone]

 

Hey guys, I have a mandolin pickup that is really a dynamic mic element. It has an XLR out that is great for connecting to an XLR mic input on my MixWiz, etc. Here's a link to a photo of one: http://www.amazon.com/Schertler-DYN-M-for-Mandolin/dp/B001T9NUMQ Balanced output, low impedance, sounds nice! Every now and then, though, I need to plug it into an amp, DI, or DI/preamp that doesn't have an XLR input. So, I rummaged through my equipment shelves and found an old adapter that I bought 20 years ago from Radio Shack. Seems like it works okay. It looks like this: http://www.parts-express.com/pe/showdetl.cfm?Partnumber=242-4776 So, I have a nice mando, a nice pickup, a nice mixer, nice speaks, etc. All of this is part of the same chain as my 'parts is parts' Radio Shack adapter. It occurred to me that some adapters might be 'better' than others, or certainly better than my 20 year old Shack'dapter! Just wondered if anybody here had an opinion, or a suggestion on a particular brand of adapter to buy. Thanks, Harry

 

 

I betting the 20 year adaptor has better parts then the new ones and I doubt the line transformer has changed design that much in the past 20 years. Maybe use a a DI box like LA Braggs which has a pre-amp section along with EQ to color the sound or a Radial DI box which is neutral in sound.

[agedhorse]

If it works ok for you then stay with it.

[harryh]

 

If it works ok for you then stay with it.

 

 

Thanks, Horse, now I can rest easy!

[Dogoth]

Other than some loss of gain (granted this could be an issue if it's severe enough, or you like overdrive), just a balanced XLR to unbalanced 1/4 TS adapter should work OK. Putting a high z load across a source looking for a low z load won't effect tone, just volume. Try it with just an adapter (no transformer) and see if it still works OK (that way you are eliminating possible overload of a cheap transformer).

 

Just a thought.

[agedhorse]

For your application, JR's suggestion would also work, pin 1 will probably need to be connected to either 2 or 3 for this adapter to work. Depends on the driving source.

[harryh]

Thanks, JR, Horse, twostone,

 

You know, I really appreciate being able to come here, ask a question and get some answers and opinions.

[harryh]

 

For your application, JR's suggestion would also work, pin 1 will probably need to be connected to either 2 or 3 for this adapter to work. Depends on the driving source.

 

 

Horse, your last reply came in while I was typing. I'll take a look at the connection in the next few days.

 

Thanks again! HH

[harryh]

Mr. Horse and other interested parties,

 

I have some questions that relate to the original topic, but also to the concepts of impedance matching and/or voltage matching mics with my Mix Wiz XLR channel inputs.

 

I've been 'studying up' on impedance matching, voltage matching, the 'ten to one' rule, etc., by looking at various overviews on the internet:

 

http://www.tape.com/resource/impedance.html

 

http://www.soundonsound.com/sos/jan0...ceworkshop.asp

 

For example, I've read that most low impedance mics have an output impedance of 150-200 ohms. In contrast, the mandolin 'pickup' (really, it's a mic element in a flat capsule that adheres to the top by use of adhesive putty. Weird story, but it sounds good!) has an output impedance of 500 ohms, which is considerably higher. Now, my Mix Wiz 3 board's mic inputs have an input impedance of 2Kohms, or 10Kohms if the pad is used.

 

The questions:

 

1) Does the 'ten to one rule' that I've read about (lowest possible output impedance and a relatively high input impedance by at least a factor of ten) apply to microphone scenarios?

 

2) As mentioned, the pickup/mic's output impedance is 500 ohms, which blows the '10 to 1 rule' all to hell with my Mix Wiz unless I engage the -20 dB pad. Is that important?

 

3) Does anybody know why a mic impedance would be 500 ohms and not 150 to 200 ohms?

[agedhorse]

Wait, didn't you say you were going into the 1/4" input? This input has an impedance of > 10k.

 

500 ohms into a typical mic input of say 2.5-3.5k is just fine. 10:1 is not a strict rule but a rule ofthumb that carries with it some specific assumptions.

 

Specifically, what mic element are you talking about? Is phantom power involved? You mention flat and adhesive mounted... are you sure it's not a piezo crystal and 500k isn't the output impedance?

 

I now have more questions than when you started.

[harryh]

 

 

 

thanks, Harry

[agedhorse]

Diidn't know about the DI, I thought you were going directly into the 1/4" input on a console or an amp.

 

If there's plenty of level then you do not need the transformer. If there's not enough level then you need the transformer. Part of the impedance matching is the stepping up of signal voltage, but if there is plenty of gain (I kind of doubt there is) without, then you need to use the step-up (matching) transformer. Low to hi Z will step up voltage along with impedance, that's how the transform works.

 

Using the XLR input on the MixWiz, you are just fine and plenty well matched.