transparent gain

[krytikal1]

i'm looking for a really transparent stereo or dual mono gain stage in my chain. something with extremely high headroom, and stepped or easily repeatable settings. it would be the last thing in my chain if i wanted to make up gain into the converter. either to allow a lower level through the chain for a smoother ride, or a higher level into the converter for more artifacts . i'd love for it to be unoticable (if possible) if it were left inline but not in use. i really don't need more than a couple db, but up to 6 would be cool.

i don't mind diy, and i'm not necessarily looking at a console.....but am open to any suggestions. i'm farely happy with what i have, but always looking for other color.....or in this case, lack thereof.


thanks,

k

[cooker]

TK Audio BC1 Stereo Buss Compressor (...and the "sound' of the gain cell is almost non-existent...)

Saw this on the banner here, might be what you're looking for? (I never used it by the way)

[okydoky]

hi,

check out daniel weiss' stuff, including the a to d converters which i believe have what you are lookiing for built in.

i think he probably has some other boxes that would help you if you don't want to buy the converters.


right.

[bob katz]

Originally Posted by krytikal1

i'm looking for a really transparent stereo or dual mono gain stage in my chain. something with extremely high headroom, and stepped or easily repeatable settings. it would be the last thing in my chain if i wanted to make up gain into the converter. either to allow a lower level through the chain for a smoother ride, or a higher level into the converter for more artifacts . i'd love for it to be unoticable (if possible) if it were left inline but not in use. i really don't need more than a couple db, but up to 6 would be cool.

i don't mind diy, and i'm not necessarily looking at a console.....but am open to any suggestions. i'm farely happy with what i have, but always looking for other color.....or in this case, lack thereof.


thanks,

k

I built one with a pair of THAT 1606 line drivers and I'm really happy. I use a multiturn dial pot to get the gain adjustment. THATs are quite transparent, and yes, the output gain stage is probably not a good place to be colorful.

[Mars 2078]

Originally Posted by bob katz

I built one with a pair of THAT 1606 line drivers and I'm really happy. I use a multiturn dial pot to get the gain adjustment. THATs are quite transparent, and yes, the output gain stage is probably not a good place to be colorful.

Interesting...please if you can, could you share some other info about it?
I read that you used also the Api 2500 gain to adjust the level before the converters.

I use above all the STC8 gain with a little bit of the vari mu before

[Adam Dempsey]

Originally Posted by Mars 2078

I use above all the STC8 gain with a little bit of the vari mu before

More than enough clean gain there (the STC-8). I'd use that second only to the custom console here, which has no 'sound' whatsoever.

[pmx]

i'm using my weiss' in the beginning of the chain, and a stepped tk audio bc1 (mv, thomas made one on request, very nice!) for driving my ntp's at the end.

tc6000 has a nice gain, and a diy THAT solution isn't too bad either...

[lucey]

Originally Posted by krytikal1

i'm looking for a really transparent stereo or dual mono gain stage in my chain. something with extremely high headroom, and stepped or easily repeatable settings. it would be the last thing in my chain if i wanted to make up gain into the converter. either to allow a lower level through the chain for a smoother ride, or a higher level into the converter for more artifacts .

From a 'pure' transparency standpoint this is a losing battle, as no matter the solution you'll sense a loss. If you're open to a little color then tailor the solution in that direction.

Can you alter the input ref of your converter? Or just get the gain in small pieces with other pieces in the chain?


(and the BC1 is very clean but not neutral when placed last, I had it there.)

[dietrich10]

Has anyone tried the Portico 5043 for this use? someone (cant remember) mentioned they used it just for gain adjustment at end of the chain and rarely used it to compress

D

[bob katz]

Originally Posted by Mars 2078

Interesting...please if you can, could you share some other info about it?
I read that you used also the Api 2500 gain to adjust the level before the converters.

I use above all the STC8 gain with a little bit of the vari mu before

I used to use the API 2500 for that, but the 2500 is no longer in my mastering chain, it's been moved to the mix room.

You can easily calibrate the output stage of any decent compressor to supply the appropriate gain before the converters. But sometimes all I want to do is D/A/D with no processing in between, for the subtle softening that provides (you can call that a loss or an improvement depending on your point of view) and the calibrated clipping is then relegated to the THAT 1606-based output stage. Do you need the schematic of the line stage I used to get the calibrated output?

[krytikal1]

Originally Posted by bob katz

Do you need the schematic of the line stage I used to get the calibrated output?

That would be great to check out. Any suggestions on stepped dial pots?

Thanks Bob,

K

[LudwigM]

im also interested in the line-stage schematik. im using the chiswick reach valve compressor as my last tool before the lavry blue. and i cant drive it loud enough without hard compression.. so maybe i will try this thing...

[Mars 2078]

Originally Posted by bob katz

I used to use the API 2500 for that, but the 2500 is no longer in my mastering chain, it's been moved to the mix room.

You can easily calibrate the output stage of any decent compressor to supply the appropriate gain before the converters. But sometimes all I want to do is D/A/D with no processing in between, for the subtle softening that provides (you can call that a loss or an improvement depending on your point of view) and the calibrated clipping is then relegated to the THAT 1606-based output stage. Do you need the schematic of the line stage I used to get the calibrated output?

Thank you for the reply!!

If you can it would be great!

[Table Of Tone]

Try to get hold of a pair of Neuman R75's and hook them up to a 24 volt power supply.
These have half db steps for input and output gain and are really transparent.
They sound killer!

I believe George Marino uses these to hammer his ADC.

[pmx]

those r75 look nice! never seen them secondhand though. wouldn't that be a nice product for chris muth or someone like him to bring to the market?

[engmix]

Originally Posted by Table Of Tone

I believe George Marino uses these to hammer his ADC.

Ah, i was wondering about this. I had him master a single a year or so ago, and the end result was bloody loud as hell, but had no distortion or limiter artifacts. Not to say he used the gear you mentioned, but what ever tricks he has up his sleeve, they work very well.

[bob katz]

Originally Posted by Mars 2078

Thank you for the reply!!

If you can it would be great!

It's a THAT 1606 (which natively gives 6 dB gain) preceded by a balanced o pad with two 5K series resistors on the balanced input (one 5K on each leg) and a variable pot (variable resistor) (calibrated dialtrim pot) on the load side of the O pad (the variable resistor is across the input to the chip). It varies from neg infinity gain to +2 dB or so.

The hardest part you'll have to deal with is the surface mount chip!

[dietrich10]

how many 'Katz Gain' boxes would need to be preordered to make it worth your time?

I already know the answer...

[Mars 2078]

Originally Posted by bob katz

It's a THAT 1606 (which natively gives 6 dB gain) preceded by a balanced o pad with two 5K series resistors on the balanced input (one 5K on each leg) and a variable pot (variable resistor) (calibrated dialtrim pot) on the load side of the O pad (the variable resistor is across the input to the chip). It varies from neg infinity gain to +2 dB or so.

The hardest part you'll have to deal with is the surface mount chip!

Thank you very much!!

[dcollins]

Originally Posted by bob katz

The hardest part you'll have to deal with is the surface mount chip!

They probably sell an evaluation board for this chip that is already wired up.

Personally I would go with a standard opamp solution for this app as the 1606 can't produce anymore than 6dB gain, and would always recommend stepped attenuators for mastering level adjustments.


DC

[bob katz]

Originally Posted by dcollins

They probably sell an evaluation board for this chip that is already wired up.

Personally I would go with a standard opamp solution for this app as the 1606 can't produce anymore than 6dB gain, and would always recommend stepped attenuators for mastering level adjustments.


DC

Instead of a stepped attenuator, I'm using a multiturn numerical dial trim pot and for exactly 1 dB, etc. a small Dymo label table suffices to dial in the amount of gain preset. It takes up a lot less space and fits nicely in a 1U panel along with a pair of 1606's on a board.

In my application (analog insert gain adjust just before the ADC) I NEVER need more than 1 or 2 dB of gain, so a max of 6 is more than enough.

THAT may have a few surface mount to DIP adapter boards available with 1606's on them, but I cannot say for sure. Attached is a little photo of the two dial pots and the cheat sheet dymo label. There's enough resolution for you to see that one pot is set to 250 and the other to 256 on the dial for irrelevant reasons...

[Paul Gold]

Originally Posted by bob katz

The hardest part you'll have to deal with is the surface mount chip!

Did I miss something? What needs to be SMT when it's some resistors a 1606 and a pot?

[dcollins]

Originally Posted by Paul Gold

Did I miss something? What needs to be SMT when it's some resistors a 1606 and a pot?

Good point, it's available as a standard 8 pin DIP package.

I see nothing but disadvantages to using a pot in this application fwiw. Size certainly isn't an issue, and the tracking looks easy to bump or mis-set.


DC

[Table Of Tone]

Originally Posted by bob katz

Instead of a stepped attenuator, I'm using a multiturn numerical dial trim pot and for exactly 1 dB, etc. a small Dymo label table suffices to dial in the amount of gain preset. It takes up a lot less space and fits nicely in a 1U panel along with a pair of 1606's on a board.

In my application (analog insert gain adjust just before the ADC) I NEVER need more than 1 or 2 dB of gain, so a max of 6 is more than enough.

THAT may have a few surface mount to DIP adapter boards available with 1606's on them, but I cannot say for sure. Attached is a little photo of the two dial pots and the cheat sheet dymo label. There's enough resolution for you to see that one pot is set to 250 and the other to 256 on the dial for irrelevant reasons...

I like your style!

[Paul Gold]

Originally Posted by dcollins

I see nothing but disadvantages to using a pot in this application fwiw. Size certainly isn't an issue,

I'd use a switch too. I have a ton of Electroswitch C4's which need to be shoehorned into a 1RU. I like them though. It turns out a military contractor in my building is a dealer so I can piggyback small quantities. I found this out after I ordered 200pcs. At least I have them...

[bob katz]

Originally Posted by Paul Gold

Did I miss something? What needs to be SMT when it's some resistors a 1606 and a pot?

Several of the THAT chips are only available in SMT. I am pretty sure the 1606 is one of them. I'm using the balanced output to advantage and it requires fewer support parts.

You can use a 1646, which is on an 8 pin dip I believe, with some support electrolytics...

I imagine the 1646 sounds as transparent as the 1606, similar internal parts slightly different topology. If I didn't have the smt to dip adapter board I wouldn't have fussed with the smt, surface mount is a pain in the....

The 1606 is also balanced in and so once I got four boards working it proved to be a universal building block. One of my DACs really liked to see a balanced input to get the cleanest (no hum) run from my main rack to my processing rack. The other DAC was clean no matter what type of load over the same cable run.... go figure.

[bob katz]

Originally Posted by dcollins

Good point, it's available as a standard 8 pin DIP package.

I see nothing but disadvantages to using a pot in this application fwiw. Size certainly isn't an issue, and the tracking looks easy to bump or mis-set.


DC

Wrong. These dial trims are stable as a concrete foundation and singularly repeatable. These 20-turn pots cannot be accidentily turned even if you bump into them. I would revise your recommendation for a stepped attenuator in this application to a: calibratable, repeatable, dependable one. You can even repeat within 0.1 dB if necessary with this dial pot. Most 1 dB stepped attenuators you can get except for custom models you would build with resistors and a little rotary switch would take up more than 1U height. These dialtrims are among my favorite little chatchkas, I've replaced the output pots on my MR 70 with dial trims and log the output gains in the loadin notes as 3-digit numbers, with 0.1 dB accuracy.

[bob katz]

Originally Posted by Paul Gold

I'd use a switch too. I have a ton of Electroswitch C4's which need to be shoehorned into a 1RU. I like them though. It turns out a military contractor in my building is a dealer so I can piggyback small quantities. I found this out after I ordered 200pcs. At least I have them...

Ooh, that's sweet, Paul. Want to sell some of them? If you ever need a dialpot I have about 25 of them I got surplus.

[Paul Gold]

Originally Posted by bob katz

Want to sell some of them?

They are for a large project I am working on, so they are spoken for. They really don't fit very well in a 1RU case. You have to bend the tabs and heat shrink over them so they don't touch the case.

[Paul Gold]

You're right the 1646 is the 8DIP part. You only have to install the electrolytic caps if you will be feeding unbalanced loads. Phantom power will blow them up so you have to install diode protection if there is a chance they will see 48v.

I installed the the caps and diodes on the Pico compressor. I haven't made one without them to see if it makes a difference. That thing is very clean. I don't imagine it will make much of a difference.