Sontec: hardware bypass, balanced THAT I/O, MS, power supply - at one PCB!

[Igor]

0.2 db difference: not related to IJR DOA's. Trimmers are for minimization of DC offset.
Check all resistors in audio path on MS board.... also, did you tuned it for minimum crosstalk in MS by MSBAL pot (left bottom on MS/Bypass pcb)?

 

[duantro]

How do you check for the ms adjustment? With an audio analyzer or a voltage measurement somewhere?

 

[ilfungo]

0.2 db difference: not related to IJR DOA's. Trimmers are for minimization of DC offset.
Check all resistors in audio path on MS board.... also, did you tuned it for minimum crosstalk in MS by MSBAL pot (left bottom on MS/Bypass pcb)?

I went ahead in the test ...
if increase or decrease the input level of the difference in M / S changes from 0.2 to 0.1 in a strange manner, a higher level or lower = 0.2
mid-level = 0.1
If I change the frequency up to 3000 Hz = 0.1 from 4000 up difference = 0.2
I also tried to replace the IC but nothing changes.
Which resistors i must check?
Thanks

 

[Igor]

How do you check for the ms adjustment? With an audio analyzer or a voltage measurement somewhere?

Feed signal to left channel; short right to ground (no signal);
ms is in; adjust the pot for minimum signal at right output.

0.2 db difference: not related to IJR DOA's. Trimmers are for minimization of DC offset.
Check all resistors in audio path on MS board.... also, did you tuned it for minimum crosstalk in MS by MSBAL pot (left bottom on MS/Bypass pcb)?

I went ahead in the test ...
if increase or decrease the input level of the difference in M / S changes from 0.2 to 0.1 in a strange manner, a higher level or lower = 0.2
mid-level = 0.1
If I change the frequency up to 3000 Hz = 0.1 from 4000 up difference = 0.2
I also tried to replace the IC but nothing changes.
Which resistors i must check?
Thanks

Now I lost you

Most of folks were say "Welcome to analog world". Well, not much curious, but still interesting what is going on here

EQ is off on both channels; MSBAL pot adjusted for minimum signal leakage; feed 0db from analyser and measure output! Dats all! Should work fine.

About digging into details.
If you use soundcard for testing, take into acct, it should be calibrated with rms voltmeter.
Than, if you use handheld fluke as rms voltmeter, take into acct it shows bit different at different frequencies.

I used my oldy heavily modified Boonton 1120.
If the eq input is referred to 0db, outputs of the eq are within 0.1 db with or without ms independently of frequency.
I know Boonton gives me about -0.05 db at 20kHz vs 1kHz and have to find some time to adjust the variable cap at input card, but I know the unit's error...so fine with me.
Now, 0.02db is within the normal error of rms detector of Boonton at 1V RMS 1Khz which is really not bad.
Audio precision have almost same precision but have also a digital compensation, so, reading can be bit better.

If the eq will be used for mastering, you can order from me Uni-Q, digitally controlled, completely tested etc. - it will be available very soon.
For the DIY use, if you do mastering version, ahm... you do it on your rescue

If you build this EQ for mastering, 1% or better resistors should be used everywhere and no pots - switches only.
And I'd avoid cutting the boards like some folks did and running long cables to switches.

Stepped mastering unit should be done with this thought from the start.

If the eq is used with pots for mixing tracking etc, 0.1db difference between channels is fine, mixer's fader or gain knob have way more tolerance.
The tolerance of pots when eq engaged will add more unpresision and imperfection...but that's the way it goes

Well, just some OT thoughts

If you will explain me as for complete stupid what is going with your EQ and what is the test setup, I will try to be helpfull.
Measuring units should be in db's or volts but how can i understand what is 0.1 or 0.2?

 

[ilfungo]

HI igor
thanks for the reply!
the difference of 0.2 db I measure with eq out, but in M / S
in the same situation but in L / R channels are perfect!
What can be?
Thanks

 

[dandeurloo]

Hey guys I just wanted you to know that I am working on a case for this as the standard Sontec case wont work.  I am on my second revision of it now.  I am building a stereo eq now to test in it.  The front panel has a lot of stuff going on so its gonna be close.  But if I can get it all in my chassis it should be a very nice project.  I have the back panel all worked out and there is more then enough space inside the case for everything.

I will let you know once I can confirm it all works.

 

[duantro]

Hey Dan,
Everything fit in your case just fine, with a little drilling for the extra switches on the far right side of the front panel for me. I also just ran wire for the xlr cutouts as well. I originally thought that the m/s/ bypass/LR switch was going to be replacing the in/out switches, since I saw Igor's prototype did this. * see my previously confused posts.  ??? After people shed light for me, I didn't have a problem squeezing them in.

 

[Volume11]

Hey guys I just wanted you to know that I am working on a case for this as the standard Sontec case wont work.  I am on my second revision of it now.  I am building a stereo eq now to test in it.  The front panel has a lot of stuff going on so its gonna be close.  But if I can get it all in my chassis it should be a very nice project.  I have the back panel all worked out and there is more then enough space inside the case for everything.

I will let you know once I can confirm it all works.

Ah sweet, this just seals the deal for me. I'll be ordering soon after Xmas. Thanks for this one Igor!

 

[dandeurloo]

Yeah, I just finished test fitting stuff.  These use the most front panel width of anything I have done to date!

The case will work but will require a little more drilling/dremeling on the right side panel.  Its about a 5 min job.  I found that it was just as easy to use a dremel tool and cut out a chunk of the side panel so that Igor's nice little PCB for the switches and LED's fit.  I can't move all the holes any further to the left or the left front panel mounting screws will interfere with the Silk Screen.  So the moral of the story is that its not the best fit, but it does work and will look very nice. 


I can post photos if that will help you guys.

 

[Volume11]

Yeah, I just finished test fitting stuff.  These use the most front panel width of anything I have done to date!

The case will work but will require a little more drilling/dremeling on the right side panel.  Its about a 5 min job.  I found that it was just as easy to use a dremel tool and cut out a chunk of the side panel so that Igor's nice little PCB for the switches and LED's fit.  I can't move all the holes any further to the left or the left front panel mounting screws will interfere with the Silk Screen.  So the moral of the story is that its not the best fit, but it does work and will look very nice. 


I can post photos if that will help you guys.

I'd like to see some photos, please.

 

[Igor]

Hey guys I just wanted you to know that I am working on a case for this as the standard Sontec case wont work.  I am on my second revision of it now.  I am building a stereo eq now to test in it.  The front panel has a lot of stuff going on so its gonna be close.  But if I can get it all in my chassis it should be a very nice project.  I have the back panel all worked out and there is more then enough space inside the case for everything.

I will let you know once I can confirm it all works.

Standard 2RU 250mm depth case, some milling/engraving directly from Corel file I sent you. You take it too hard

HI igor
thanks for the reply!
the difference of 0.2 db I measure with eq out, but in M / S
in the same situation but in L / R channels are perfect!
What can be?
Thanks

If in ms you don't have level difference between channels, just leave it.
I checked one I have at workshop, it was -0.12 db ms vs lr. The difference between l-r channels was 0.03 db.
Good enough. I wish all equipment will have same precision

 

[duantro]

Here's the Front panel holes that I did. Worked great minus the drill slipping and the  1 small nick. Internally I used a jeweler's saw and just carved out an indention on the inside front panel mounting flange between the screw holes. 

 

[ilfungo]

HI igor
thanks for the reply!
the difference of 0.2 db I measure with eq out, but in M / S
in the same situation but in L / R channels are perfect!
What can be?
Thanks

If in ms you don't have level difference between channels, just leave it.
I checked one I have at workshop, it was -0.12 db ms vs lr. The difference between l-r channels was 0.03 db.
Good enough. I wish all equipment will have same precision
[/quote]

maybe I explained evil ...
in M / S have a difference of 0.2 dB between L / R
In stereo mode, the channels are perfect!
I wonder, why?
Is this normal?
thanks

 

[dandeurloo]

Here's the Front panel holes that I did. Worked great minus the drill slipping and the  1 small nick. Internally I used a jeweler's saw and just carved out an indention on the inside front panel mounting flange between the screw holes.

Yeah, I will have a new front panel for these so you wont have to do any drilling and it gives just a little more room.  But people will still have to cut out the side panel a little bit for the switches and screws to fit.

Did yours fit fine in a 9" case?  The 11" case I am using seems to have more then enough room and bet it would fit just fine in the 9".

 

[duantro]

My case is an 11" one.

 

[Igor]

0.2db difference between channels in ms a bit high imo.... if eq is not used for mastering, just leave it; maybe.... a wrong resistor somewhere???

 

[ilfungo]

Hi Igor Can you tell me which resistor I must check for M/S?
Thanks

 

[duantro]

Here's my chop job on the case to make room for switches.
Thanks for the m/s adjustment tips Igor! I'll get it calibrated.

 

[dandeurloo]

I powered up my unit and everything test good.  Now I am just waiting on some DOA's that can take the 24v's so I can test this baby.  It will be nice to hear what everyone has been talking about.

 

[duantro]

I powered up my unit and everything test good.  Now I am just waiting on some DOA's that can take the 24v's so I can test this baby.  It will be nice to hear what everyone has been talking about.

Enjoy Dan! This thing sounds really good. Really smooth and musical. I'm glad I built it. Thanks again Igor.