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Not so Easy to Skip the Preamp?


I have just tried to assemble a system for a third office, using a Behringer A500 in stereo.

I have tried a Hagtech USB interface to output SPDIF ito an Audio Research DAC5 and both the optical and RCA outputs of a Behringer interface.

As I am only using one input (the PC) I hoped to skip a preamp and any extra sets of cables.

In all three cases as above, however, the sound was pretty bad - congested, veiled and distorted almost as if the speakers were blown.

Is this because neither an interface box or the ARC DAC would have sufficient gain to drive a power amp correctly?

This was not immediately obvious to me because there is sufficient volumn and the VU meters on the amp are well below clipping - it just sounds bad.

Thanks for any ideas - maybe a cheapo Parasound preamp would help for these types of "systems".
cwlondon
ojgalli
165 posts
 
Better check the amp. You may have been lucky with the A500s, but I was not. For me, 3 out of 5 were bad, one within a month, two straight out of the box. I also found that the volume controls are not good—best to leave them at full output.
cwlondon OP
1,210 posts
 

Main desktop system:

Computer USB to USB hub > Behringer Interface Box > Interface optical out to DEQ24 > Also, analogue out from Cablevision HDTV box to DEQ2496 > 2x Behringer A500 (in mono) > ATC SCM 7's and/or Epos ELS3's

In this case, I use the DEQ2496 as a "preamp" of sorts to switch between computer and HDTV. Sometimes, I also experiment with the RTA and equalize the speakers.

I was curious to see how much better the computer audio might sound if

a) I was using the Hagtech and SPDIF instead of the USB hub and optical cable and

b) I was using the ARC DAC instead of the Behringer DAC. (In this configuration, I am not using the 2496).

As I have spare ATCs and Behringer amps, I was otherwise hoping to "A/B" the demo, and was surprised when it sounded terrible.

Perhaps Ojgalli is correct and it is simply a bad amp. I have generally had much better luck however, using another pair of A500s since 2007, which I leave on 24/7 and use every day for both HDYV and computer...

Thank you, everyone, for all of your help and thoughts and Happy New Year.
cwlondon OP
1,210 posts
 

Ojgalli,

OK so I checked the Behringer and it was perfectly fine, and sounded surprisingly good.

In fact, I did another A/B vs a Bryston amp and at least at pre clipping levels, there was no obvious winner. Thanks God I paid < $500 for the Bryston on Ebay and not the $1895 MSRP.

Then, I reconnected everything using the Hagtech USB to SPDIF, into the Audio Research DAC, and straight into the Behringer.

This time, for some reason, everything worked fine.

So, in fact, it was easy to skip the preamp, so I will consider using these amps for desktop applications with small monitors.
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