Emu PatchMix experts inside...

[Solude]

I got my HeadAmp Reference with a dact stepped and the gain makes notches 6-10 the usable range. Realistically its 6-8 for most music and 8-10 for quiet music.

Anyway long story short I need to drop 10dB off the top to get more range on the dact. Options are sending it into Justin to be modded for a gain of 3x from the current 8x, use inline attenuators like the Harrison's HeadRoom sells or use a trim pot in PatchMix.

So for the Emu virtuosos how harmful is a trim to the final result? I currently have WAVE patched to S/PDIF using a SEND. Inserting a trim a bad idea? Let me know.

 

[Erukian]

trim_pots dont hurt your sound quality at all.. if that's what your asking.

It's not like an analog pot where things can get distorted.

-Joe

 

[Solude]

It would certainly be my preference, i.e. most cost effective but am unsure if the process is lossy or if the lower line level would effect the amps performance.

 

[jefemeister]

In the strictest sense, a -10dB gain will caues 1 bit loss in resolution. Certainly not a big deal, probably not noticeable either. I'd rather do that then use an attenuator. I guess the best solution is to get the amp reworked, but I'd say the alternatives are perfectly fine.

 

[Solude]

Meaning a drop to 23bit or 15bit? 23bit obviously would mean no drop since only the first 16 means anything.

 

[Erukian]

From what i've read, the e-mu does everthing at 24bit. So if your feeding it 16bit material, it'll use 8 bits of padding.

I don't know about losing 1bit every -10dB, but i can tell you, digital attenuation is much better than analog

If anything, try out the trim_pot cause it's free and it's something you can do to your setup 'now'.. If that's not good enough for you (it should be imho) go and get the card modded..

My two cents.

-Joe

 

[Jasper994]

I generally use -9.11db and have never noticed much (if any) difference. It's a quick and easy solution that works very well. This is particularly true if you watch a lot of movies on your rig as well. Movies tend to be a good bit quieter and I end up using -5.36 and turning up the volume a bit more on my amp. If you lower the gain on the amp itself, you may find that it won't get loud enough on quieter material.

 

[Solude]

That was my other concern. DVDs especially are VERY quiet on my PC. As long as the trim isn't harmful in an audible way, its definitely the best option.

I think part of it is also encoding. When I play a CD it sits at roughly -6dB but WMA or MP3 are pegged at 0dB. So -6dB trim really just brings it back to 'normal' levels. The other -4dB is for me

 

[Solude]

Have to ask, Jasper, why such odd -dB settings? Why not just a straight -9dB or -5dB?

 

[gerG]

Quote:

Originally Posted by jefemeister In the strictest sense, a -10dB gain will caues 1 bit loss in resolution. Certainly not a big deal, probably not noticeable either. I'd rather do that then use an attenuator. I guess the best solution is to get the amp reworked, but I'd say the alternatives are perfectly fine.

Ummm, my binary math is rusty, but I think that it is worse than that. An additional bit doubles the amplitude (or resolution). That coincides to roughly a 3 db increase. A 10 db attenuation takes a 16 bit stream down to under 13 bit. Padded to 24 bit BEFORE attenuation and you are in safe city (24 db of room to play with). btw, doesn't 16 bit audio reserve one bit for sign and 2 for parity check?

Can someone provide evidence that the Emu cards pad to 24 prior to signal manipulation? I am not arguing, I just had not heard that before.


gerG

 

[thomaspf]

As a simple approximation 6db ~ 1 Bit

16 bit ~ 96db dynamic range
24 bit ~ 144db dynamic range

This is in the digital domain only. For any real system the DAC limits the resolution by means of it's noise floor and distortions. 120db is a very good value for dynamic range. This translates to 20 bits of true resolution before noise. You can of course also hear into the noise floor as you all can attest to by listening to a badly tuned radio.

Whether a digital volume control is better or worse than analog is dependent on the resolution and algorithm used. Digital is not necessarily better!

Cheers

Thomas

 

[gerG]

I am perplexed (could be the scotch)

Where did 16 bit = 96 db come from?

gerG

edit: actually I know that that number comes from 20*log10(2^16). What is confusing me is that is peak to peak, I think. I need to go think about this one for a bit (hah!).

 

[thomaspf]

As I said simple approximation but works pretty well for most practical purposes.

Cheers

Thomas

 

[Kram Sacul]

What's with all these wacky odd db numbers? I thought you're supposed to set Patchmix at 0.0 and use your amp to control the volume. That's what I do at least.

 

[Solude]

Kram read the first post