Balanced Mic Preamp

[AudioFreak]

Hi,

I'm looking for ideas / schematics for a balanced mic preamp for use in the PA system at my church... The mics are Shure sm48 / sm58 and similar ... I'd like something that sounds decent (and low distortion IS an issue here) rather than the typical cheap PA gear. The design can use discretes or opamps. Any ideas?

Regards.

 

[pinkmouse]

Hi AF

Can you afford/get hold of input transformers? If so, there is a nice circuit I built from Walt Jung's new brick book on opamps that I use with my iMic to get sound into my laptop.

 

[moamps]

I'm looking for ideas / schematics for a balanced mic preamp for use in the PA system at my church... The mics are Shure sm48 / sm58 and similar ... I'd like something that sounds decent (and low distortion IS an issue here) rather than the typical cheap PA gear. The design can use discretes or opamps. Any ideas?

Hi,

- Analog Devices - SSM 2017/19
- Or, I can send to you one good schematic from Sound..... consoles. (2SA970/2sc2240/TL072).
- Do you think about using some kind of voice compressor?

Regards

 

[Sawzall]

second the thought

for thinking about processing. Worth every nickle for live sound.

 

[AudioFreak]

We've got (primative) processing but need some gain earlier on in the chain. Input transformers (anything even slightly decent at least) are probably well outside my budget. I've looked at the 'all in one' preamps offered be analog but I'd rather use opamps / discretes as stated in my 1st post.

Regards.

 

[millwood]

take a look at those instrumentation opamps (you don't have to use an instrumentation opamps. an ordinary opamp will do) and you will get more than enough ideas.

 

[AudioFreak]

I'm hoping to do something that sounds reasonably decent 1st time around which is why I was asking for help. I could work something out on my own but I dont have the time or money to try endless components / combinations ... I really need something that will do the job pretty well straight out of the box (or off the soldering iron as the case may be).

Regards.

 

[Brett]

Freakster,

Use the INA103. It's not too shabby sounding, has good specs and was available from Farnell or RS last time I looked.

 

[moamps]

I'm hoping to do something that sounds reasonably decent 1st time around which is why I was asking for help.

Hi,

In Elektor 11/97 was published one stereo microphone preamp with AD SSM 2017. This amp work very good with studio condenser microphones (Sennheiser, AKG, Neuman)(my own experience). There is PCB, also. And you can order chips like samples, I guess. This is very good solution for you 150$ Shure.
If you are interested, I can send to you this article in pdf form.

Regards

 

[Edu Silva]

Hi, all

In Elektor 11/97 was published one stereo microphone preamp with AD SSM 2017.

Analog Devices discontinued this IC. The better substitute is the TI/BB INA217:

http://focus.ti.com/docs/prod/productfolder.jhtml?genericPartNumber=INA217&pfsection=desc

But you can find a good source of schematics at Rane website:

http://www.rane.com

For exemple, their stand-alone mic preamp:

http://www.rane.com/ms1b.html

Scroll down and click on "schematic".

hope this hleps,

 

[AudioFreak]

I forgot to mention that I would like true balanced input and true balanced output.

 

[millwood]

I forgot to mention that I would like true balanced input and true balanced output.

some datasheets will give you balanced input utilizing anywhere between two to three op amps (try TL082 datasheet). balanced output can be done via two opamps (one inverting + one non-inverting, or one inverting buffer following another inverting/non-inverting opamp).

The schematics at Rane that Edu Silva mentioned has both balanced input and output.

 

[millwood]

I'm hoping to do something that sounds reasonably decent 1st time around which is why I was asking for help. Regards.

if those op amps can be used collecting extremely weak and wide spectrum signals, it will work for audio as well.

 

[Sparhawk]

I'm looking for ideas / schematics for a balanced mic preamp for use in the PA system at my church... The mics are Shure sm48 / sm58 and similar ... I'd like something that sounds decent (and low distortion IS an issue here) rather than the typical cheap PA gear. The design can use discretes or opamps. Any ideas?

You might try this. it has a balanced, low noise discrete front end. The output is unbalanced, but that is not really a problem if the preamp is located reasonably close to the next piece of equipment in the chain. If you really want a balanced output, you can add something like this .

For an IC solution, I think someone already mentioned the Burr-Brown INA103 .

 

[millwood]

if the BB isn't available, y ou can build one using this schematic in TL082 datasheet (bottom of page 10).

http://cache.national.com/ds/TL/TL082.pdf

Of course, you don't have to use the lowly TL082,