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Gear / Technical Help => Cables => Topic started by: page on January 16, 2010, 12:21:49 AM

Title: sonically neutral attenuators?
Post by: page on January 16, 2010, 12:21:49 AM
Can attenuators be sonically neutral or really close to it? I've gone through two now with various problems (one flipped the channels even). They all seem to hit on the bass to the order of about 4-6db so I end up with stuff thats brighter then it normally is.  :-\

ok, after reading: http://www.uneeda-audio.com/pads/
I wonder if part of my bass issue is a mismatch of load.
Title: Re: sonically neutral attenuators?
Post by: greenone on January 16, 2010, 01:18:47 PM
Was it the M-Audio one that flipped the channels? I've been thinking about picking one up but not if it flips channels obviously...
Title: Re: sonically neutral attenuators?
Post by: yug du nord on January 16, 2010, 03:06:20 PM
Are you talking attenuation boxes or individual "barrels"?  I'm guessing boxes cause I don't see have a pair of barrels could flip channels......

I'm in need of a pair as well, so this caught my interest.  I've seen some decent looking barrel style attenuators made by Shure and AT that I've been thinking about.
Title: Re: sonically neutral attenuators?
Post by: page on January 17, 2010, 12:37:18 AM
The M-Audio one lost the bass, the one before that from AT which was a cable flipped the channels. I haven't used a box, these have either been cables/barrels.
 
:-\
Title: Re: sonically neutral attenuators?
Post by: SmokinJoe on January 20, 2010, 12:43:28 PM
I made a set using just resisters and I couldn't hear any difference (used that Uneeda/pads page as a guide.)   There is a little bit of science involved in choosing the right resister values so you match impedance of input and output, but it's not rocket science, and I expect anyone in that business would know how to do it.  I can envision someone using impedance matching transformers, and that inductive load might change the sound?

I made balanced XLR > mini TRS so I could run my V3 analog > Korg MR1.  This had 20db drop and allows me to have the V3 meters match the Korg meters.  I have run V3 with analog going into these cables > MR1, and at the same time the digi out of the V3 > R4.  Then I made a wave file with alternating one source, then the next etc, and I couldn't hear a difference.  What I was trying to test was V3 A/D vs. MR1 A/D, but again... I couldn't hear a difference.  Are my ears not fussy enough?  Perhaps.

My suggestion is look at make your own as described on "uneeda", or try Niaint (spelling??).   I have a set of 15db XLR attenuators from him you can borrow for a test if you like.
Title: Re: sonically neutral attenuators?
Post by: page on January 20, 2010, 01:06:53 PM
I have a set of 15db XLR attenuators from him you can borrow for a test if you like.

Dunno, I'm going to tinker with it a bit.  :-\

Would current direction play a role? That dawned on me this morning as a possibility...
Title: Re: sonically neutral attenuators?
Post by: SmokinJoe on January 20, 2010, 06:02:20 PM
What are the attenuators for?  XLR? Between what devices?  Given that info it might make more sense.

Are you trying to do a balanced>unbalanced conversion at the same time (or vice versa)?
Title: Re: sonically neutral attenuators?
Post by: rowjimmytour on January 20, 2010, 06:32:58 PM
I made two pairs to run from SDB>R4 and found this link very helpful:
http://www.uneeda-audio.com/pads/
XLR>RCA -30db 15'
(http://i5.photobucket.com/albums/y181/rowjimmytour/-25dBpad/DSCN0956.jpg)
XLR(stubbies)>RCA -20db 6'
(http://i5.photobucket.com/albums/y181/rowjimmytour/DSCN0927.jpg)
Note when I made the 2nd pair (XLR>RCA 15' I found that longer was better to get around the SDB and more pad was a good thing so I never had to bug the FOH during the show ;)
Title: Re: sonically neutral attenuators?
Post by: page on January 20, 2010, 11:15:41 PM
What are the attenuators for?  XLR? Between what devices?  Given that info it might make more sense.

Are you trying to do a balanced>unbalanced conversion at the same time (or vice versa)?

unbalanced all the way.

I have a set of extremely sensitive inner ear monitors which when I use my dac/amp I can just barely get it loud enough on the gain to get rid of the channel imbalance present at low voltages without blasting my ears off. I'd like to lose about 5-10db is all.

3.5mm > 3.5mm
Title: Re: sonically neutral attenuators?
Post by: page on February 15, 2010, 06:33:47 PM
That's a power circuit--low power, but still power.  Probably the resistor values you used are too high.  What's the impedance of your IEMs?

56ohm.

I'll agree, it seems that I'm inappropriately loading the attenuator or IEM as I lose that bass down regardless of direction (I had a set of AT attenuators that just didn't work the opposite direction...)