Balanced Mic Preamp suggestions

[WA2SQQ]

Been doing some upgrading to my audio chain that will eventually feed the Flex 5000 on AM. I’m looking for an inexpensive mic preamp that has balanced audio in and out. All of the Behringer / Mackie small mixers do not offer balanced outputs. Any suggestions on what I should look for on the used market? Tried using one of the $50 variety 12AX7 preamps offered by guitar center, but this just has too much 60 hz crud coming out of it.

[N2DTS]

My vx2000 has a balanced output...
I also have an ART tube preamp someone posted about, a small thing, has power for the mic, phase reversal switch, a nice meter, input and output level pots, and a limiter. Its supposed to be balanced in and out but I am not sure it really has a balanced output or not. Was $25.00 I think, has no hum on it.
TRS and XLR input and output jacks on it, heavy metal case, backlit meter, color changing LED's.

[N2DTS]

The price is a bit high, but...

http://www.ebay.com/itm/Behringer-Ultra-Voice-VX2000-/161546883885?pt=US_Preamps_Channel_Strips&hash=item259cf1d32d

[w1vtp]

Are you saying my Behringer MIC100 doesn't have a balanced output? HMMM.

[w1vtp]

If I may, how about sharing your setup details eg.. mic cable length general hookup detail.  Maybe we can help you debug things.  I'm quite satisfied with my Behringer MIC100 and use it with a legal limit AM transmitter.  Gotta be something we all can debug.

Do you get the same hum problems going into a dummy load as you do on your antenna?

GL  Al

PS:  While I'm at it why don't I put up the manual

[Ralph W3GL]

The price is a bit high, but...

http://www.ebay.com/itm/Behringer-Ultra-Voice-VX2000-/161546883885?pt=US_Preamps_Channel_Strips&hash=item259cf1d32d

The bidding hasn't moved off $20.00 but yes, the shipping is a bit high at $25.00...  

I use one of these to modulate my TS440 and yes, it has balanced output
going direct to the balanced modulator ...

A quick reminder, in order to eliminate any ground loop (hum)  problems, the shield of the VX2000 or any other balanced preamp line should BE isolated, IE, not connected to the casing of the audio output line connecter.  Just run the audio to the ring & tip to the B. modulator input xformer...

[KD0HUX]

 A Behringer VX 2000 and a Behringer PEQ 2200 would do good that was my plan for my Flex 1000. I changed my mind . I am going for more of a ( TUBE ) sound. I plan to use a HHB RADIUS 40.  I will swap out the cheap rough sounding ruskie tubes for  European   60s vintage tubes.   If you are interested the Behringer VX 2000 and Behringer peq 2200 are  4/sale.

[w1vtp]

The price is a bit high, but...

http://www.ebay.com/itm/Behringer-Ultra-Voice-VX2000-/161546883885?pt=US_Preamps_Channel_Strips&hash=item259cf1d32d

The bidding hasn't moved off $20.00 but yes, the shipping is a bit high at $25.00...  

I use one of these to modulate my TS440 and yes, it has balanced output
going direct to the balanced modulator ...

A quick reminder, in order to eliminate any ground loop (hum)  problems, the shield of the VX2000 or any other balanced preamp line should BE isolated, IE, not connected to the casing of the audio output line connecter.  Just run the audio to the ring & tip to the B. modulator input xformer...

This might help with ground loops in a balanced line system:

http://amfone.net/Amforum/index.php?topic=37478.0

[WA2SQQ]

Currently using the same ART tube preamp that N2DTS mentioned. Actually purchased and returned it twice as each unit has 60 hz crud on the output. Pretty sure it’s not a ground loop as I can see the 60 hz on the output with nothing connected to it. Also tried using an isolation xmfr, just in case, with no change. At this point everything points to the preamp.
Mic is a Heil PR40, feeding a Behringer 2496. My goal is to keep audio balanced all the way through to the Flex 5000. Cables are short, longest about 4 ft – all double shielded.

[w1vtp]

Currently using the same ART tube preamp that N2DTS mentioned. Actually purchased and returned it twice as each unit has 60 hz crud on the output. Pretty sure it’s not a ground loop as I can see the 60 hz on the output with nothing connected to it. Also tried using an isolation xmfr, just in case, with no change. At this point everything points to the preamp.
Mic is a Heil PR40, feeding a Behringer 2496. My goal is to keep audio balanced all the way through to the Flex 5000. Cables are short, longest about 4 ft – all double shielded.

Difference between using a dummy load and using the ant?

[WA2SQQ]

Definitely not RF. Turned output down to 0 - same.

A quick reminder, in order to eliminate any ground loop (hum)  problems, the shield of the VX2000 or any other balanced preamp line should BE isolated, IE, not connected to the casing of the audio output line connecter.  Just run the audio to the ring & tip to the B. modulator input xformer...

Going to try this tonight... thanks

[Ralph W3GL]

If the shield isolation does not fix the problem then try Al's isolation xformer
scheme, that has been a cure for crud elimination for years in computer sound card
inputs, etc...

Good luck.

[W2NBC]

Good reading regarding the "Pin 1 problem" and grounding with balanced audio:

http://www.rane.com/note151.html

I see that your ART unit has a supplied "9 volt adapter" (wall-wart).. Is it a switching supply, and do you have you any other clean 9 volt source to power it up?

[WA2SQQ]

It's a wall wort, but it's 9V AC. I'm almost tempted to find a schematic and build a DC supply to bypass the crazy circuit they use. I'll try the shield trick later tonight and post results.
Thanks!

[W4RFM]

My day job is selling broadcast gear.  I can get you a DBX 286S balanced in and out with EQ and compression for way under $200 easily. Dont want to be commercial, just trying to help.
Bob

[KY4SP]

+1 for the 286S. Not as many "bells and whistles" as some but does the job very well.

[N2DTS]

I was just messing with mine last night.
I never use it, never have, only got it because it was so cheap.
I plugged my mic into it, and plugged it directly into the line input on the screen modulator and for no EQ and no compression or limiting, it sounded and worked quite well.

I do not think its a balanced output though.

I was testing it because one of the switches on the VX2000 is dirty and it gets scratchy sometimes, not very high quality...

Currently using the same ART tube preamp that N2DTS mentioned. Actually purchased and returned it twice as each unit has 60 hz crud on the output. Pretty sure it’s not a ground loop as I can see the 60 hz on the output with nothing connected to it. Also tried using an isolation xmfr, just in case, with no change. At this point everything points to the preamp.
Mic is a Heil PR40, feeding a Behringer 2496. My goal is to keep audio balanced all the way through to the Flex 5000. Cables are short, longest about 4 ft – all double shielded.

[W2NBC]

ART Tube MP..

hummmm:

http://amfone.net/Amforum/index.php?topic=16673.0


Seems like hum may just be a documented issue with your unit.. 

[WA2SQQ]

Tried lifting pin 1, without any improvement. Have to just accept the fact that this unit is a piece of excrement! May just bite the bullet a pick up a Behringer mixer that has balanced out.

[n1ps]

Good reading regarding the "Pin 1 problem" and grounding with balanced audio:

http://www.rane.com/note151.html

Absolutely correct and everyone should be aware of this issue.   Many audio boxes just pipe in crud into the boxes.

p

[N2DTS]

Note, the output xlr is balanced output, but the TRS is NOT.
The TRS input IS balanced.
For fun I put an RCA 12ax7 in mine and got a firmer lower mid range and a crisp high end with tight siblance response.
I just made all that up but it sounds good, and no hum at all.
I think its interesting I can plug it right into the screen modulator (line level) and it does not sound real bad.
Seems like it needs a high end boost, but I hear nothing over 3K so it might not sound bad at all.

[w1vtp]

+1 for the 286S. Not as many "bells and whistles" as some but does the job very well.

My 286s developed noise in the mic preamp stage so I hooked up the MIC-100 that I used to use into the line input and my stations sounds good again.  Don't understand why the MIC-100 got such a ho hum reception - it is balanced both input and output and affords both XLR and 1/4" TRS option - NO hum and is cheap.  Oh well.

My class E station has absolutely no hum and here's what I use:  EV RE-15 / Behringer MIC-100 / dBx 286s --> line level out..

[VE3AJM]

If you can find some vintage Bogen solid state stuff at a good price, they work well.

I've used the M67 and the model CFC over the years. The CFC can be configured many ways and it is immune to RFI, and the M67 was widely used in the broadcast field.

Al VE3AJM

[WA2SQQ]

Did some searching and think I'll pick up a Yamaha MG06X. It's a small mixer with two channels of balanced in / out plus some other unbalanced that I might be able to make use of. Guitar Center has it on sale at $119. All the on line comments seem trouble free. I can always return it if it has problems. Thanks for all the suggestions.

[N2DTS]

Its not rack mount, but I like the reverb.
I used to have a spring reverb that I turned up when I said long as in a llllloooooonnnnnnggggg transmission.

Someone had a design of a balanced mic preamp using both triodes of a dual triode tube.
I thought that was da bomb.