ATI Pro100 Turntable Amp Question

Hey guys and gals,

Haven't been able to find a good answer for this question. We have a Barix Exstreamer with a rca male to xlr female (Cable that is still unbalanced) into an Optimod 8400. We are a small mom and pop station so money for a matchbox is not going to appear anytime soon. We have an old ATI P100 turntable amp.

Now my understanding is that most of the old turntables (Technics SL1200 MKII) were unbalanced. So my theory is that I should be able to run the output of the Barix Exstreamer (unbalanced) into the P100 then go XLR (balanced) to the Optimod 8400. In theory I should go from -12db unbal to at least +4db bal.

Can anyone see a reason why this wouldn't work? I am just trying to re-use what we already have laying around.

Thanks!

Another thing to consider are impedance and gain differences. A typical phono cartridge represents 47k ohms impedance and -50dB level into the preamp. Most unbalanced audio sources that one would use into things like a Henry Matchbox are assuming 10K ohms and -10dB level. Chances are you would completely overload the phono preamp into distortion, not to mention the phono preamp has a built in high frequency EQ curve (preemphasis) that would make your audio sound shrill and tinny sounding.

There are less expensive 'balance box' interfaces than the Henry Matchbox, which I can't fathom one couldn't afford, considering it is your program audio we're talking about here. Broadcast Tools makes a 1-way matching balance interface, as does Radio Design Labs (RDL).

A phono preamp such as you are talking about includes the RIAA curve to boost the bass. Unless you can figure out how to defeat that, you will have very odd sounding audio. You will also have a big problem with level matching. The output of a magnetic phono cartridge is in the order of -50 dbm or even less. The output of a Barix box is about -10dbm. That is a 40 dbm difference. The result is the Barix box will overload the ATI preamp, causing lots of distortion. I've found that most Barix boxes have enough poop to drive a line level input on most devices. It is not a perfect match, but usually can be made to work. If you can't get enough level out of the RCA jacks, try using the headphone output.

I'm with Kelly, You never want to skimp on your program audio. If you can't the Henry, RDL makes the FP-UBC2 for about $185 and Rolls make a MB15b ProMatch for around $56.

I see that the OhMyGod 8400 has a minimum nominal analog input level of -4-dBu so I can see why you need the gain. But I don't think that you want to mess with converting a phono pre-amp to a "Matchbox". That's just painful because of the much higher gain of a phono preamp and the RIAA eq that has to be defeated. (Too bad your Barix box doesn't have an AES digital output that could be fed into the Optimod; their 1000 Extreamer does, don't know about the others.)

I've used these "cheap and dirty" line level converters in the past to feed streaming computers from a balanced source and they worked OK although they're probably not going to set the world on fire from an audio quality viewpoint. And you can't beat the price . . . http://www.mcmelectronics.com/product/555-8485 .