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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
4est
507 posts
 
What are you using a volume attenuator? The DAC5 only has 20 bit resolution and a digital one may throw bits away? Or it may just be that there is a impedance mismatch between them. Although my DAC has plenty of drive (Weiss DAC2 -50 ohm), with my present rig I am using a TVC. There is a small sacrifice in dynamics, but has added body and weight. YMMV, and probably will.
mechans
3,048 posts
 
Do you want SS only? Otherwise I really like the Cary preamps. I am especially fond of the AES AE-3 which I think you can still buy new although hotrodded a bit at Upscale Audio for about $1200-
I don't know if you can still buy the Parasound Z-pre?

The other really cool solution is a custom made pre by Mapltree Audio in Canada. He has standard models for about $500-600 IIRC, but if you tell Prof. Peppard what you need he can make it work for you. In general he is very reasonable. Check out his website. They are all tube however.
cbw723
89 posts
 
I assume you have tested all of the components individually in other systems and they are all working properly? If so, then what computer type are you using and what playback program? Have you checked that the computer output to the Hagtech, and the Hagtech to the DAC are all configured with compatible bit depths and sample rates? If you are using a Mac and iTunes, you must restart iTunes after changing the parameters in Audio Midi Setup.

As someone mentioned above, if you are sending 16 or 20 bits, you may also be throwing a lot of bits away. Is the volume in iTunes (or whatever your playback program is) set very low? If so, you may want to get a couple of passive attenuators and put them between the DAC and amp. They should have enough attenuation so that you playback program is near full volume at normal listening levels. You can get decent ones from Parts Express for about $25, or "audiophile grade" ones from Rothwell or elsewhere.
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