4db output from -15db professional audio from user, amplifer help please

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Gday
I want to obtain a 4db output from a normal soundcard(about -15db or something) Does anyone know how to do this, and cheaply. I am on a tight budget and i didnt even know until two days ago that pro equipment ran at 4db, now i have spent $212au on a power amp i find i need to buy a mixer or something. Please help.
Daniel
 
Hi Daniel,

I think it is -10dB out from your soundcard and in this case it´s 14dB up to get +4db out.

There are a lot of semipro to pro level interface on the market in varying price range, but one nice I have use a lot are Radio Design Labs "flat-pak range" type: FB-UBC2 unbalanced to balanced converter (input RCA connectors and output XLR connectors) and have adjustable gain from -5 to +10 dB balanced output in 600 ohms.

I think you can get it from the mostly pro-audio dealers.

If you have audioelectronics as a hobby you can easy build a own, tell me if you want some tips for this.

-Bo Hansén, Gothenburg, Sweden
 
reply -

Yes that would be very good, i found that i had a yamaha souncard lying around, but it is pretty lousy although it does have a strong output. The amp i have got takes XLR sockets unbalanced. SO id need a converter from RCA to XLR (or that large headphone socket) but it needs to be unbalanced. if you could send me any cicuits of how to do this thatd be great!!
Thanks
Daniel
 
i had a look at the product

Input impedance: 10 kOhm
Input configuration: Unbalanced
Output impedance: 150 Ohm balanced, drives 600 Ohm or 10 kOhm lines
Output configuration: Balanced or unbalanced - - - wow!!!
Frequency Response: 20 Hz to 40 kHz (+/- 0.25 dB)

One of these would be great, however i betcha itd cost an arm and a leg, if you know how to buil one anything like this id love to know.
Thanks
Daniel
 
i had a look at the product

Input impedance: 10 kOhm
Input configuration: Unbalanced
Output impedance: 150 Ohm balanced, drives 600 Ohm or 10 kOhm lines
Output configuration: Balanced or unbalanced - - - wow!!!
Frequency Response: 20 Hz to 40 kHz (+/- 0.25 dB)

One of these would be great, however i betcha itd cost an arm and a leg, if you know how to buil one anything like this id love to know.
Thanks
Daniel
 
Here is an RDL product that already has the I/O jacks on it: RU-LA2D This is a little bit more money than the Flat-Pack, but it does have the jacks. This is a great sounding piece. If you need to do this on a smaller budget, try the Ebtech : LLS-2 .This still does a decent job and won't break the bank.

If you are handy with electronics, you can easily build a basic circuit around the BB DRV134 to balance your circuit and feed your amplifier.

Cheers,
Zach
 
Remember that +4dBu / +4dBm is the operating level. Any circuitry you use should have a further 20dB of headroom.
This means you must buy a professional interface of some sort, or make one.
The suggestion by Usekgb of the DRV143 is a good one. You'll need +&- 18v supply rails at least. No non-prof sound card will be able to reach these levels.
You should be able to "****" the feedback of the 143 to get the gain you need. It may not keep all elements of it's exemplary spec, but will be well useable.
 
You could even put an op-amp before the DRV134 to get a little bit of gain. Also, when you balance a signal, you are actually sending two signals, thus doubling the voltage at the receiving end.

Also, for the most part, Pin 2 will be hot. That is the industry standard. There are still a few pro sound companie that use pin 1 as hot (what a pain!), but pin 2 hot is the standrd.

Cheers,
Zach
 
one low budget example
 

Attachments

  • unbalbal.jpg
    unbalbal.jpg
    75 KB · Views: 294
The DRV134 will give you better performance than the 5532 layout due to the fact that all of the resistors required to set the gain of the op-amps are internal and laser trimmed in the DRV134. So, in reality, using the DRV134 will be cheaper, use less parts, and will give better performance.

Cheers,
Zach
 
Hi all,

I was looking for something like Moamps' circuit to up the sub out level of my av receiver into a behringer ultracurve pro. (then onto pro amps)

I have opa 2134's lying about here, and a power supply already built. Can I use these instead of the 5532 ? - I read elsewhere on the forum that the 5532 will handle a higher voltage.

Cheers

Rob
 
:D Cheers John but...,

I've added a couple of them to an order I've just placed. How different would a 'proper' circuit be in complexity ? I've got a few transformers lying around and am looking for a UK supplier of the DRV134 right now. Can probably adapt the power supply I've got at the mo : http://sound.westhost.com/project05.htm

I'll do a search for the DRV cicuits and see what I find.


EDIT: found this : http://www.jensen-transformers.com/as/as022.pdf

Has an option without transformers...(not drv134 though)

Cheers

Rob
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.