Polarity reverse in a balanced to unbalanced input

[ccaudle]

It was frustrating not to have that feature. So here I’m thinking I’ll add it to my console build.

So you console has unbalanced inputs? I thought you said earlier it had balanced inputs:

the inputs are (could be) balanced, from there-> the signal travelling inside is unbalanced

If you have balanced inputs, as Pucho812 said in post #14 just put a switch between the XLR or TRS connector and your balanced-to-unbalanced stage.

 

[Stack]

I would add an op amp before adding a transformer just to realize a polarity inversion.

I don't recall seeing many (any?) class A consoles, while everything was class A if you go back far enough.

JR

PS; Yes the 5534 is an old soldier that has performed well over the decades, at least since the 70s.

Some of those very early mixers CBS and RCA engineering would dream up, had modules of matched transistor circuits of the 1940-1960. Dan Flickinger was clearly impressed by the early tube oriented designs. Sitting behind it made you start looking for a white lab coat. That bit over single ended was off the mark as it really defined power sources to the opamps. With a balanced front end, the bipolar supplies offered less noise. Single ended meant “+ & gnd”. Someone else showed me.

 

[thakava]

So you console has unbalanced inputs? I thought you said earlier it had balanced inputs:


If you have balanced inputs, as Pucho812 said in post #14 just put a switch between the XLR or TRS connector and your balanced-to-unbalanced stage.

I’m building a new console, so the inputs are not decided yet, but as I would want a polarity reverse switch, I guess I could go with 1:1input transformers. The question comes from the fact that the rest of the console is unbalanced aka. Eqs and auxes etc.

 

[ccaudle]

I’m building a new console, so the inputs are not decided yet, but as I would want a polarity reverse switch, I guess I could go with 1:1input transformers. The question comes from the fact that the rest of the console is unbalanced aka. Eqs and auxes etc.

Any reason in particular you would use transformers and not solid state for the inputs?

 

[Stack]

I’m building a new console, so the inputs are not decided yet, but as I would want a polarity reverse switch, I guess I could go with 1:1input transformers. The question comes from the fact that the rest of the console is unbalanced aka. Eqs and auxes etc.

Spot the looney here ! I confess to this abberation of terms.....I've been away from it a while but I think I can clear it all up, as being the perp who misconstrued a term or two.....Single ended really references most to rail voltages powering up ICs. single ended meaning a ground and a + voltage present at the IC's pinouts. Bipolar Opamps supply Plus, Minus and a ground ref. A balanced opamp. Many opamps, however, only provide the high side of the rail voltage.

 

[JohnRoberts]

Spot the looney here ! I confess to this abberation of terms.....I've been away from it a while but I think I can clear it all up, as being the perp who misconstrued a term or two.....Single ended really references most to rail voltages powering up ICs. single ended meaning a ground and a + voltage present at the IC's pinouts.

Perhaps the better term is "single supply"

Bipolar Opamps supply Plus, Minus and a ground ref. A balanced opamp.

Bipolar (two polarity) power supply, with +/- signal swing.

Many opamps, however, only provide the high side of the rail voltage.

Balanced and unbalanced have different, pretty specific meanings in the context of audio interfaces, unrelated to power supplies.

JR

 

[Stack]

Hi gang!

Building a line in console that will be unbalanced, but would like to have a polarity reverse at the input. Would putting a input transformer like this make that possible?

Best/
Tom

Have you seen Rupert Neve's mix summing mixer ? Iso iron on all inputs, and a BLEND in the transformer pot on the stereo buss. You do pay for the name but his deployment here, for me, sets the Bellweather for line level summing mixers, as the correct method. Why some "systems" give the pan pot to the DSP is beyond me, really. Why ? Speed of light electronics is about the fastest any of us will get in this life. For the sake of the discussion, I believe I'd be happier having something like this, for certain. Thoughts ? I'd bet his inserts are buffered too.

 

[Stack]

Hi gang,
Thanks for all replies.
As a reference: I had an early Trident B-range a while ago, that was unbalanced, except for the mic input (Zutt transformer) it only had a polarity reverse on mic input, not the line.
I was told back then that if I wanted that feature a line transformer would have to be added. Never did that.
It was frustrating not to have that feature. So here I’m thinking I’ll add it to my console build.

Best//
Tom

Hey Tom....There was a FET switch on those 80-B Trident input modules. I'd been advised to rip em out due to distortion adding anomalies. The 80-B was a pretty fast operating console for sure. Drums always sounded better recorded through that console.

 

[thakava]

Hey Tom....There was a FET switch on those 80-B Trident input modules. I'd been advised to rip em out due to distortion adding anomalies. The 80-B was a pretty fast operating console for sure. Drums always sounded better recorded through that console.

I had a Triad B-range from 1974.
The A-range had Zutt transformers on both the mic and line input.
What also was weird with my particular console, it was line in unbalanced but also phase reversed at the busses.
With no transformers.

 

[Stack]

I had a Triad B-range from 1974.
The A-range had Zutt transformers on both the mic and line input.
What also was weird with my particular console, it was line in unbalanced but also phase reversed at the busses.
With no transformers.

We had two 80-B's at Treasure Isle, Nashville. Fred cut a deal with John Oram and then we had a new B range with Orem modules....In the rack we had half a dozen A range modules too. The Trident B's were all over Nashville....Norbert Putnam, at the Bennett House in Franklin had an A range running in their main room ( the former livery stable ).....from the 70-80's most rooms ran MCI gear. Tastes do change. The only other A range I ever worked on was in A at Cherokee in LA. Rod Stewart recorded "Hot Legs" on THAT console. Truly British, both Tridents and Neve's were in the biggest rooms in England, until SSL came along. Uggg...

 

[mcsmarket]

Quite interested in this group! I'll throw this out there , where does Electrodyne fit in the mix of all the great consoles? I have one.

 

[thakava]

If you're building from scratch, I'd go with JR's suggestion in post1: Inverting opamp

pol_inverse.gif shows two channels
Calrec PQ1347_input_polarity.JPG shows calrec's implementation with 5532 opamp

esp pages on this: Phase Inversion Switch

/Jakob E.

Thanks! It is a very good contender. Would need to design a circuitboard. Any good and easy programs for that?
Best //
Tom

 

[ccaudle]

Would need to design a circuitboard. Any good and easy programs for that?

I am a little confused. Without this inverting op-amp circuit your entire console was going to have no active electronics, and this alone is what will create the need to design a PCB?

 

[Stack]

Quite interested in this group! I'll throw this out there , where does Electrodyne fit in the mix of all the great consoles? I have one.

I recorded and mixed on an Electrodyne console at Jones Sound, Houston, Texas 1966.
Those consoles seemed the first of the manufactured consoles back then. Most studios I’d visit around Hollywood in the 1960s, most studios had custom built consoles, most were one off builds, as I recall. Spectra Sonics arrived 1968 to my awareness.we bought a pair of mic pres and EQs. Mama Joes, I believe, ended up with a custom Spectra console after Alan Parsons arrived. He showed the new console & studio to me a year after I’d returned to Houston.

 

[Stack]

I recorded and mixed on an Electrodyne console at Jones Sound, Houston, Texas 1966.
Those consoles seemed the first of the manufactured consoles back then. Most studios I’d visit around Hollywood in the 1960s, most studios had custom built consoles, most were one off builds, as I recall. Spectra Sonics arrived 1968 to my awareness.we bought a pair of mic pres and EQs. Mama Joes, I believe, ended up with a custom Spectra console after Alan Parsons arrived. He showed the new console & studio to me a year after I’d returned to Houston.

Archie Bell and the Drells, “tighten up” and early Mickey Newberry albums plus a Micky Gilly project was all cut on Electrodyne mixers to a Scully 280, 8 track recorder. BJ may have recorded his first there too, “I’m so Lonesome I could Cry”. That was Houston. Walt Andress did the FEVER TREE at his studio by the old Hobby airport.

 

[Stack]

Archie Bell and the Drells, “tighten up” and early Mickey Newberry albums plus a Micky Gilly project was all cut on Electrodyne mixers to a Scully 280, 8 track recorder. BJ may have recorded his first there too, “I’m so Lonesome I could Cry”. That was Houston. Walt Andress did the FEVER TREE at his studio by the old Hobby airport.

I believe Electrodyne morphed into Quad Eight at some point. I had a very early Quad Eight console, Cowboy Jack Clement gifted me with Allen Reynold’s blessing. The old blue Quad Eight from Clement “A”, Ray Stevens, Everything Is Beautiful” and then moved to Allen’s Jacks Tracks where it recorded, “Don’t It Make My Brown Eyes Blue”, then ended up in the basement’s pool room for years of storage before I got it. It went into a trailer I ran around Nashville with recording people live. Only a memory now. Like Electrodyne, Quad Eight designed it’s own hybrid opamps. They. Got better sounding, much later.

 

[mcsmarket]

I believe Electrodyne morphed into Quad Eight at some point. I had a very early Quad Eight console, Cowboy Jack Clement gifted me with Allen Reynold’s blessing. The old blue Quad Eight from Clement “A”, Ray Stevens, Everything Is Beautiful” and then moved to Allen’s Jacks Tracks where it recorded, “Don’t It Make My Brown Eyes Blue”, then ended up in the basement’s pool room for years of storage before I got it. It went into a trailer I ran around Nashville with recording people live. Only a memory now. Like Electrodyne, Quad Eight designed it’s own hybrid opamps. They. Got better sounding, much later.

Wow! Thanks, great to see your experience with the console and the song and artist history. Quad Eight yes. I have read where the original op amps caused some issues, spent a lot of time in, under and around the board, even had some of the ACN's (active combining networks) repaired by Don King years ago, picked up 14 used from Australia recently. Do you think the API opamps would be an improvement? What do you think was lacking in the originals? Also maybe you know these switching modules in each channel, you can switch any single channel to any other channel I've always wondered why that would be necessary? It has a whole mixdown desk on the right side of the console.

 

[thakava]

I am a little confused. Without this inverting op-amp circuit your entire console was going to have no active electronics, and this alone is what will create the need to design a PCB?

Yes, indeed. Which is why thought of the 1:1 transformers to invert the polarity at the input.

 

[Stack]

Wow! Thanks, great to see your experience with the console and the song and artist history. Quad Eight yes. I have read where the original op amps caused some issues, spent a lot of time in, under and around the board, even had some of the ACN's (active combining networks) repaired by Don King years ago, picked up 14 used from Australia recently. Do you think the API opamps would be an improvement? What do you think was lacking in the originals? Also maybe you know these switching modules in each channel, you can switch any single channel to any other channel I've always wondered why that would be necessary? It has a whole mixdown desk on the right side of the console.

I’ve long forgotten the specifics regarding I/O & voltage requirements but that old quad eight console sounded fine. A big sluggish on transients so the API 2520 I believe is a matched transistor opamp with much faster recovery from hard transient signals. The 2520 is class A. The hybrid round pinned opamps seemed much slower…., made drums sound like cardboard boxes. Chip pres like TLO 71-72 and AD 5534 had designs much faster, better for transient generators like drums and grand pianos. Bass improved dramatically after that 13v/ms slew rates became more available. You don’t hear the transient disparity as much with vocals & guitars….; slow is ok recording those sources.

 

[Stack]

I’ve long forgotten the specifics regarding I/O & voltage requirements but that old quad eight console sounded fine. A big sluggish on transients so the API 2520 I believe is a matched transistor opamp with much faster recovery from hard transient signals. The 2520 is class A. The hybrid round pinned opamps seemed much slower…., made drums sound like cardboard boxes. Chip pres like TLO 71-72 and AD 5534 had designs much faster, better for transient generators like drums and grand pianos. Bass improved dramatically after that 13v/ms slew rates became more available. You don’t hear the transient disparity as much with vocals & guitars….; slow is ok recording those sources.

If hot rodding old electronics pushes buttons for you, dive in ! I do have different prefs for instrument vs mic combos. Drums need the higher speeds… rise times/ recovery/ all that jazz play integral parts in delivering snappy sounding recordings. You cannot fix a sluggish opamp, they are what they are by design. Stability was way more important in the beginning. Some of those opamps had so much internal gain, as soon as you turned a knob, massive uncontrollable feedback could occur. Feedback gain can get very squirrely and unstable. The API stuff won’t disappoint.