EQ Unity Gain ??

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04-29-2010, 12:17 PM
SEAWOLF97

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EQ Unity Gain ??

so I was biking around yesterday and found a Spectro-Acoustics EQ in pristine condition...noted model number and went home to read about it...

the web said : " Spectro Acoustics was one of the three companies started up by engineers who left Phase Linear. Spectro Acoustics was started by Robin Gudgel. The two other companies were Tapco and Carver, started by Bob Gedgel and Bob Carver, respectively."

and

210r 10-band,

" To those of you familiar with Spectro Acoustics gear You are aware of the quality of build. This mid/late 70's high end manufacturer produced some well built, good sounding equipment. This piece is over built, all the parts were military spec at the time as I remember......sliders are silicone lubed and should not have a cleaner used on them or they will loose their characteristic "feel".......the weight is 12lbs, with total immunity to external magnetic fields, distortion figures are IMD....0.0075% at any output up to10 volts composite, THD........less than 0.05% at 1 volt rms output......S/N is better than 90 db below one volt........dynamic range noise floor is over 105 db below full output...... The functional versatility of the Model 210 is unsurpassed by any product of its kind. The model 210 was far ahead of its competition in terms of maximum signal-handling ability, or so called headroom. Its integrated circuit servo op amp output stage can directly drive as many as ten super power amplifiers in parallel without problems. The controls/switches have a solid expensive feel. The sliders are not illuminated. There are10 band centers per channel with unity gain adjustments for each channel providing 30db total adjustment(+15db/-15db). The Model 210 is pristine black /gold brushed aluminum, 1/4 in. faceplate and comes with a hard wood cabinet extra. I found the unit quiet in operation, utilitarian/rugged in appearance and use. This is not a cosmetically flashy piece, it looks more like an expensive professional studio piece of gear. Very well made."

so I went back last night and bought it..since one is listed for $169 at classicaudio.com

QUESTION:

there are "unity gain" adjustments for both right & left channels....my understanding of this is not rock solid..tried the web, but most hits were about UG on amps....

can someone here clarify me on the UG function as it works on EQ's ????
04-29-2010, 12:28 PM
Robh3606

Well this is my take. When you use EQ you can lower the average level or increase it depending on how it is adjusted. That gain control helps compensate for any level changes caused by your EQ curve. Also helps to make sure you have enough headroom using a lot of boost. I think Soundcraftsman had a pinknoise and level lights on some EQ's to help you set that control. I have a gain control on my Urei 539's as well and I had them on my old Dynaco SE-10 as well.

Rob:)
04-29-2010, 01:15 PM
grumpy

yep. These controls just slide the whole gain vs. frequency response up or down.

If you mostly used band cuts, you might want to slightly deviate from unity gain in the
positive direction... as an example. Personally, if I found it necessary to use such a device,
I'd leave it at 0dB (no gain or attenuation) and try not to cut or boost more than 6dB
anywhere ... especially boost.

A 10-band EQ is really a tone control that's hard to set without training and practice.

An old op-amp based one is more than likely going to get between you and the music
at some point. They look cool in a rack. They are good learning tools. They can make
crappy recordings sounds less crappy.

Is my opinion coming through? ;)

Looks like a fun piece.
04-29-2010, 09:54 PM
BMWCCA

Soundcraftsmen used LEDs to balance the output level. Their "unity-gain" controls were labeled "adjust lights for equal intensity" right on the front panel.

My third-octave units are quite a bit more useful than the 10-band, but I find them all useful as loudness controls and easy to bypass when not needed.
04-30-2010, 10:23 AM
SEAWOLF97

Quote:

Originally Posted by BMWCCA

Soundcraftsmen used LEDs to balance the output level. Their "unity-gain" controls were labeled "adjust lights for equal intensity" right on the front panel.

My ADC Soundshaper 3 parametric does it the same way ...but even when I set the pre on MONO and adjust the LEDS...the gain usually ends up non equal in the 2 channels.
05-01-2010, 09:30 PM
Titanium Dome

As many here know, I am a big Soundcrafstmen fan. The unity gain is an interesting and potentially very useful feature. Rather than do a lot of quoting, I think this is one of the better discussions I've read on the subject.

http://www.audiokarma.org/forums/sho...d.php?t=171151

For posterity here's my current Soundcraftsmen list:

Amps
2 A100
3 A200
2 A400
1 A2502
1 Pro Power 3
1 Pro Power 4
5 PCR800
1 S800
1 S860

Preamps
1 P100
1 Pro Power 4
2 DX4100 (w/ EQ)
3 DX4200 (w/ EQ)

Scan-Analyzers
1 AS1000
3 AE2000

EQ
3 RP2215-R

Tuner
1 T-6002

Receiver
1 3000A
05-01-2010, 10:19 PM
BMWCCA

Quote:

Originally Posted by Titanium Dome

For posterity here's my current Soundcraftsmen list...

You deserve to have a Pro-EQ 44. :D

http://www.canuckaudiomart.com/image...4972&is_user=0
05-02-2010, 06:29 AM
Titanium Dome

Thanks! Shall I send you my shipping address? :D
05-02-2010, 09:49 AM
SEAWOLF97

1 Attachment(s)

Quote:

Originally Posted by Titanium Dome

As many here know, I am a big Soundcrafstmen fan. The unity gain is an interesting and potentially very useful feature. Rather than do a lot of quoting, I think this is one of the better discussions I've read on the subject.

http://www.audiokarma.org/forums/sho...d.php?t=171151

thanx for the link TD,,,after reading the AK thread, I realized that somewhere around here I have a Soundcraftsman EQ lurking too...:o: (just need a nudge sometimes)

one of these:
05-04-2010, 04:49 AM
LowPhreak

Always liked Soundcraftsmen. SAE too. :)
05-04-2010, 07:20 AM
BMWCCA

Quote:

Originally Posted by Titanium Dome

Thanks! Shall I send you my shipping address? :D

:) I'd rather present it to you in person! ;)
05-04-2010, 09:20 AM
hjames

Quote:

Originally Posted by BMWCCA

:) I'd rather present it to you in person! ;)

:crying:
You could present it to ME in person ... its a shorter drive, for sure!
05-04-2010, 10:59 AM
boputnam

Quote:

Originally Posted by grumpy

I'd leave it at 0dB (no gain or attenuation) and try not to cut or boost more than 6dB anywhere ... especially boost.

+1

Quote:

Originally Posted by grumpy

An old op-amp based one is more than likely going to get between you and the music at some point.

+1, too. :p

And remember that any filter imparts a change to the signal phase. Fewer (and fatter) is better (but this is most easily achieved with PEQ's)...
05-04-2010, 12:13 PM
Titanium Dome

Quote:

Originally Posted by BMWCCA

:) I'd rather present it to you in person! ;)

Quote:

Originally Posted by hjames

:crying:
You could present it to ME in person ... its a shorter drive, for sure!

Hmm. :hmm: Well yes, but what about the free tour of the T-Dome JBL museum and the Synthesis® One Array audition? :p