THAT4301 compressor

[steves.mastering]

I've tried using the search function but havent seen anyone mention this.
On the Version 1.7 PCB, is there an error on the silkscreen. It says C15, 22u. However, looks like that should actually be called C12.
Just thought i'd point it out in case anyone else comes across this

 

[tonedude]

One comment about stereo linking. I found that hard linking collapses the image quite a bit, and when I designed the 2500, I put in the variable link control, and it usually sits about 50%. If you link an old 1176 or 525, they link at 50% which allows both sides to be attached but 50% of the CV from the left hits the right. So if a mix has a strong element in one side, it doesn't suck the other side down. A 3 way switch would work, L=hard link, center off, R=50%...

Inspired by the above post I'm trying to figure out how to implement this in my LA Audio TCX-20 that use the THAT4301 VCA. To "hard link" the two channels you just connect pin 5 on both RMS modules, but what about softlinking at about 50%... ? Have anyone done that with the THAT4301?

The one solution that I could think of is to link them with a resistor in between, and just use trial and error to determine the appropriate size for "soft link" resistor, maybe a pot to make linking variable?

The other thing that I have to figure out is if it's possible to do this with one set of controls for, threshold, ration, attack and release? I guess I have to use both sets of controls in the CV sidechain to implement a soft link in the TCx-20 comp. In the stereolink mode in the TCX-20, one set of controls for the CV sidechain is bypassed when the stereolinkswitch is pressed.

Link to full schematic
https://gearspace.com/board/showpost.php?p=4038646&postcount=16

 

[abbey road d enfer]

The one solution that I could think of is to link them with a resistor in between, and just use trial and error to determine the appropriate size for "soft link" resistor, maybe a pot to make linking variable?

The problem with this solution is the impedance of this node is extremely variable, so one resistor value would not fit all possible states.
I would suggest you use a potentiometer between the top of Vr103 and Vr203 and adjust to your taste. I would think a value of about a few kiloohms should do it.
It wouldn't be a perfect solution because the percentage would be variable anyway.

 

[tonedude]

Yepp, the solution I though of wasn't working out... at all...

I'll try your solution Abbey road d enfer!

 

[FIX]

depending on how you want to link them, you can link thresh, after ratio, actual CV going to VCA, etc. I usually summed them into each other.

 

[AUDIO FREQ]

Id like to purchase this kit, but do I need 2 PCB's for stereo mode? Or is there a single PCB stereo mode available?

P.s. The 4301 chips I have are SMD mounted...I suppose I will have to make an adapter board to fit this build.

 

[KA-Electonics.com]

One comment about stereo linking. I found that hard linking collapses the image quite a bit, and when I designed the 2500, I put in the variable link control, and it usually sits about 50%. If you link an old 1176 or 525, they link at 50% which allows both sides to be attached but 50% of the CV from the left hits the right. So if a mix has a strong element in one side, it doesn't suck the other side down. A 3 way switch would work, L=hard link, center off, R=50%...

When the capacitor nodes of the RMS detector outputs of the 430X are hard-coupled it is called "True Power Summing" and was the basis for the stereo Pico compressor.

EDIT: It's galvanic but not actually hard linking in the sense that current summation occurs rather than greater of two envelope peaks which is what it electrically appears to be.

 

[abbey road d enfer]

So if a mix has a strong element in one side,

Which would be a strategic error in the context of a stereo mix, unless one would recreate the aberrations of early stereo attempts, such as the Beatles "stereo" albums, with vocals on one side and drums on the other.

it doesn't suck the other side down.

Actually, it's a good indicator of a wrongly balanced mix.

A 3 way switch would work, L=hard link, center off, R=50%...

Perfectly justifiable for almost unredeemable mixes.

 

[Script]

aberrations of early stereo attempts

Early Rolling Stones had that too. Hard pan. Irritating. Almost like demo or quick session take.

 

[abbey road d enfer]

Early Rolling Stones had that too. Hard pan. Irritating. Almost like demo or quick session take.

It was a common disease at the time; almost all pop records had it.
It was a limitaion due to the absence of multitrack recorders.

 

[Brian Roth]

In Ye Olde Days, 45 RPM records and AM radio were mono. However, it wasn't uncommon for "smaller" studios to have a 2 channel/track tape deck and a mono machine for mixdown. First session I ever attended (1967?) was for a neighborhood garage band's session. The studio was kind of a dump, but did have two Ampex tape machines. The entire band played to one channel of the 2 track until they had a decent take, then overdubbed vocals on track two. The 2 tracks were then mixed down to the mono deck. The studio had a mono cutting lathe, so we each walked out with our very own 7" 45 RPM copy of the two songs!

If there had been a "stereo" release from that....entire band left, all vocals right <g>.


Bri

 

[Script]

Slightly before my time. Radio and audio in my early childhood was all mono -- so wouldn't even have noticed.

And that's how I mixed my very first recordings ever. Basic instruments building up by bouncing back and forth in mono. Last take however was played live and mic'ed in stereo -- thanks to a stereo tape machine.

 

[KA-Electonics.com]

Which would be a strategic error in the context of a stereo mix, unless one would recreate the aberrations of early stereo attempts, such as the Beatles "stereo" albums, with vocals on one side and drums on the other.

Actually, it's a good indicator of a wrongly balanced mix.

Perfectly justifiable for almost unredeemable mixes.

Give a listen to "Blue Moon" by Julie London. It's a feast for the ears (and eyes). String bass left, Julie center, guitar right. Very tasteful. You can visualize the trio on stage.

I used that song for a True Power Sum demo for the Pico. The center image was rock stable.

 

[Cqwet Dbdfte]

It seems like great many people misunderstood 2-channel sound vs. stereophonic sound.
Blumlein method goes back to the 1930s and yet many did not get the memo.
I found the following note on the back of a jazz LP from 1959 interesting.

Too much technology does not guarantee a good recording.
https://en.m.wikipedia.org/wiki/Alan_BlumleinAgree Beatles recordings were simplistic, as were many of the sound reproducers of the era.
Not much marketing effort is spent on increasing appreciation for good sound, it is not visual nor printable.

 

[abbey road d enfer]

Give a listen to "Blue Moon" by Julie London. It's a feast for the ears (and eyes).

Sure, mainly for the talent of the three persons involved, but I really question the "stereo" effect.

Very tasteful. You can visualize the trio on stage.

Sems very unnatural to me. More so on headphones.

I used that song for a True Power Sum demo for the Pico. The center image was rock stable.

For sure. Perfect tracking between side is a prerequisite for that kind of mix.
Without it, the bass would constantly steer to its opposite side.
I've always been a proponent of tight stereo tracking. that's why I abandoned FET's or optocoupleurs for stereo compressors.
VCA's only. Never dug seriously in PWM.

 

[KA-Electonics.com]

Rosalfonso Bortoni shared THAT's 4305 to THAT4301 adapter layout and schematic with me back in 2022. I should have posted it earlier but didn't know about this thread until recently. IIRC they hadn't actually built one to check the layout so it's good simon, PedalPCB and others have taken the ball and run with it. Rosalfonso originally sent this to Profusion who, until recently, hosted it on their site.

 

[abbey road d enfer]

I found the following note on the back of a jazz LP from 1959 interesting.
View attachment 120517

In the absence of a real technical discussion explaining how it differs from a 2-tack recording, this could be pure marketing BS.

Too much technology does not guarantee a good recording.

That's for sure.

Agree Beatles recordings were simplistic, as were many of the sound reproducers of the era.

It's clearly documented in Geoff Emerick's book and in "Recording the Beatles" (p.402-404) that the mutation from mono to stereo was reluctantly adopted by SE's and producers, with inconsistant help from technicians and equipment limitations. I would think the situation was similar within most recording organizations.

 

[Cqwet Dbdfte]

Dear Abbey,
It is rare to find anything related to recording techniques on an album cover, this is a rare one, I would not expect anything other than marketing lingo on a cover. The image of the needle in the track is cute, I think the needle just found its way out of the haystack.
This was in the 50's, Blumlein two-mike was from the 30's, one would think that the memo had been passed around in the 60's. Maybe because electrical instruments lack a true acoustic presentation any semblance to a stereophonic recording was tossed aside, and the buying public did not expect it anyway.
https://en.m.wikipedia.org/wiki/Blumlein_pair

 

[abbey road d enfer]

Dear Abbey,
It is rare to find anything related to recording techniques on an album cover, this is a rare one, I would not expect anything other than marketing lingo on a cover.

I agree, but sometimes I feel I would rather have nothing than something as uniformative as that.

This was in the 50's, Blumlein two-mike was from the 30's, one would think that the memo had been passed around in the 60's. Maybe because electrical instruments lack a true acoustic presentation any semblance to a stereophonic recording was tossed aside, and the buying public did not expect it anyway.

It seems there was a lack of communication between classical and pop SE's. Stereo classical recording techniques have always concentrated on a "natural" stereo image.
"Pop" SE's seem to have looked down on classical SE's for their lack of adventuresomeness, which, in that case, is wrong IMO.

 

[Gavin Pursinger]

Great thread...in trying to stereo mic my 100 yr old 7 foot grand my matching mics options are limited. I have considered the reasonably priced Aavantone CK40 stereo LDC with pattern options for each capsule to try Blumlien and MS...I am sure it is not a C24...bit it ain't $ 25 grand and seems the best affordable entry into this world
Anyone used this mic ?.THX