Quad 8 .... whats the skinny?

[John Hardy]

Paul Wolff said:

Some will take a capacitor and resistor between the collectors of the input differential stage to lower the gain at higher frequencies. Dean used the chokes in the emitter side to do the same thing.

Deane did NOT use the emitter inductors to lower the gain at higher frequencies. The emitter inductors have absolutely nothing to do with lowering the gain at higher frequencies. They increase the gain at lower frequencies to reduce the noise voltage in the audio bandwidth. It is the emitter resistors that determine the high-frequency gain and stability of the stage.

To quote from Deane's paper about the 990:

Emitter resistors of 30 ohms are required for high-frequency stability, but these increase the noise voltage by more than 3 dB above the case without the emitter resistors. To prevent the noise increase, emitter inductors can be placed in parallel with the emitter resistors.

Thank you.

John Hardy
The John Hardy Co.
www.johnhardyco.com

[John Hardy]

Regarding the 990, Paul Wolff said:

It did not sound very good with the steel core transformers.

Can you be more specific about what models of steel core transformers the 990 did not sound very good with?

Thank you.

John Hardy
The John Hardy Co.
www.johnhardyco.com

[ToneLux]

Originally posted by John Hardy
Paul Wolff said:

Deane did NOT use the emitter inductors to lower the gain at higher frequencies. The emitter inductors have absolutely nothing to do with lowering the gain at higher frequencies. They increase the gain at lower frequencies to reduce the noise voltage in the audio bandwidth. It is the emitter resistors that determine the high-frequency gain and stability of the stage.

To quote from Deane's paper about the 990:

Thank you.

John Hardy
The John Hardy Co.
www.johnhardyco.com

You guys are way to jumpy. OK, so they increase the gain at lower frequencies because they short out the 30 ohm resistors. OK the resistors set the high frequency gain, which is lower than the low frequency gain.

So what you are saying is that with the inductors, the gain is higher for the low frequencies and lower for the high frequencies.

What I am saying is the gain is lower for the high frequencies and lower for the low frequencies.

And, without the inductors or resistors, the gain would be higher over all the frequencies.

So what you are saying is it's hotter outside than inside. I'm saying it's cooler inside than outside.

Hmmm.

[ToneLux]

Originally posted by John Hardy
Regarding the 990, Paul Wolff said:

Can you be more specific about what models of steel core transformers the 990 did not sound very good with?

Thank you.

John Hardy
The John Hardy Co.
www.johnhardyco.com

The 990 sounded the best with the nickel core transformers. The 2520 sounded best with the steel core transformers. Both op-amps were designed with each designer's theory of what they felt was to go with it. The 2520 doesn't sound good with nickel, as it was optimized for the steel. The same goes for the 990. Now, since this is a word parsing contest, I would have to correct my self by saying that the steel sounded better with the 2520 opamps because they were optimized for them. A normal opamp doesn't sound as good because it doesn't react incorrectly with the steel, making it all sound better.

Of course, you must think I am saying that the steel sounds better than the nickel, which I didn't say. But the studio's that I have worked with over the years selling more than 40 consoles, the overall agreement was if someone wanted to replace the 2520s with 990s on the summing bus because they were quieter (they like a lower input impedance and don't start generating noise +n as soon as the 2520 does), they always sounded better with the nickel core transformers than they did with the steel ones. The same goes with the 2520. They may have sounded cleaner with the nickel transformers, but they sounded better if the nickel was being driven by 990s.

We've gone over this for years, and as many times as the 990 and nickel are spec wise better, people still like the fatness of the 2520 and steel. No way around it. Just a fact.

Jeeezzus you guys are either over sensitive or need a couple of beers.

[Mr. Fancy Pans]

Regarding my comments of Deanne Jensen, I met no disrespect at all. I spoke out of turn, what was told to me by one of the early Quad Eight engineers I interviewed for this article. Since then several engineers have called me to set the record straight on this particular individual.

This is part of the reason this article is taking so long, trying to get the facts straight and debunk the fiction. You have to also keep in mind that most of these gentlemen are in their 70's & 80's so their memories may be a bit foggy at times. In my excitement I posted information that I did not verify (this will not happen again). I have since talked with the original owner of Electrodyne/Sphere as well as two of the managers for Quad Eight/ Langevin. I now have 5 different individuals (who were there) proofing this article prior to me sending it in.

It's an interesting history of the audio world.

Larry DeVivo

[ToneLux]

I hope someone is learning something from this other than how to parse words and make everything into an insult.

My whole focus on these news groups is to raise awareness of how things work and why they are the way they are, without boring everyone with technical terms and legally correct verbage.

[ToneLux]

Originally posted by Mr. Fancy Pans
Regarding my comments of Deanne Jensen, I met no disrespect at all. I spoke out of turn, what was told to me by one of the early Quad Eight engineers I interviewed for this article. Since then several engineers have called me to set the record straight on this particular individual.

It's an interesting history of the audio world.

Larry DeVivo

The history of all these companies in those days were all intermixed. The Mecore guys then to the API guys, some split and went on with Quad 8, then to this and that. The real question is if the Melcore guys brought the 2520 to API, or were they fired for sexual harrassment and had to find other jobs and didn't know how the 2520 worked? Were the guys that left API and went to Q8 a good thing or a bad thing, or were they draftsmen or test guys? Did Dean ever see an op-amp design before the 990 or did he wake up one morning and say "i'm going to change the world". Did Rupert design the discrete op-amp or did one of his engineers? Did I really invent Post-its? Who invented the Pan pot? Was it the guy who left company A and right after he joined company B they came out with it? Coinsedence or Conspiracy? Maybe one of them was actually on the grassy noll. I heard that one of the guys from Mackey was the photographer that took the original fake movies from Area 51 during the moon landing...

We should construct a family tree at one of the AES shows, and let anyone come by and add to it. That would be fun. Of course, we may find out that they all came from one place in the beginning...

But, it still wouldn't answer the questions of when and where the technology was passed on or invented from. This will always remain a secret, and maybe it is best that way, because some of the best around didn't really invent anything, they just empowered others to do their best and to reach inside their hearts and come up with something that they thought was "better".

Now I want to buy everyone a little puppy.

[Slipperman]

Truly wonderful to see you Rocket-Scientist EE's bashing the living hell out of each other.

And I mean that most sincerely.

You guys are all passionate about the craft. And it is evident in these postings. Most of which I do not really understand on the component level.

I can tell you this.... I twist knobs for a living... Do it all day and night long, most days. And a few of the guys posting here in this thread, have made, or are currently making, some products that have made my job a joy to perform.

Thank you.

Best Regards,

SM.

PS. Also wonderful to see the Sphere/ED/Q8 family of "LeftCoastFilmDesks" getting some recognition. It's long overdue. There were some VERY good sounding and both practical and innovative designs from this bunch/era.

[ToneLux]

One thing all those console had in common was simplicity. When you design with discrete amps, you can't buffer everything, so you have to think hard.

Most of them had (amp count):

1) mic pre

1) input amp, serving as the pre fader amp too, sometimes it was the mic pre in a different mode

2) EQ, maybe had some discrete buffers, but for the most part, 2 amps

1) post fader amp that drove the panner and the sends and the busses and the solo.

Then

1) summing amp feeding the master fader

1) Booster amp, feeding the outside world.

Then the pressing plant, then the record store and your home.

6 or 7 amplifiers. I think today, the only console with that count is the API stuff. Everyone else has tons of ICs.

This is why all the Ouside the Box summing stations sound so good. Nolo-Buncho-Amplifcacio

It makes me feel so warm... I miss the smell of Ampex 456 in the control room....

[TheSoundSteward]

Originally posted by ToneLux
You're parsing words. The chokes are there to tame the high frequencies.
...
I am stating this in laymans terms, so others will be able to understand more about opamp design, since this is a public forum,
...
Dean used the chokes in the emitter side to do the same thing.
...
So, not to sound like a broken record, I prefer opamps with lower gain because they are naturally more stable, and that is why I said the 990 is like a lose cannon, because it has so much gain.

Paul,

I am indeed parsing words. It was my mentor Deane Jensen that first taught me that when addressing scientific issues, the words one uses are critically important to successful communication. Deane always insisted that he see the final print galley of any article he wrote in order to prevent editors from botching it. In one article he was discussing an IR drop (which is the voltage drop that happens in a wire when current flows through it). Some non-technical editor who was apparently unfamiliar with Ohm's Law, in the desire to be helpful, substituted the word "InfraRed" for "IR", which made the whole sentence into nonsense.

I believe that most "laymen" can understand a lot about all kinds of technical stuff if the person who really understands it well can explain it simply, but accurately. There is no need to mis-state what is really going on in order to "simplify" it. Usually the gory details (like the math) are not necessary to convey the principles. The book "The Art of Electronics" by Horowitz and Hill is a great example of how complicated electronic subjects can be explained in simple, understandable language.

I will once again try explain clearly for you and anyone else interested that the chokes in the emitter circuit of the 990 have no influence on its high-frequency compensation. They do NOT serve the same function as the RC network between the collectors of other opamp designs. The chokes bypass the high frequency compensation in order to make the 990 perform better in the audio band.

Your comments about high frequency instability of opamps, including overshoot, ringing, and oscillation degrading their sound quality are exactly correct. That is the reason that Deane worked so hard to adjust the internal compensation in the 990 so that it did not have overshoot, ringing and oscillations. The 990 is a great sounding amplifier precisely because it is so stable. In addition, its high gain in the audio band gives it superior distortion performance to amplifiers with lower gain. The trick with high gain amplifiers is that they take a lot more design skill to properly compensate than lower gain types.

To say that "high gain" as a property, makes any opamp better or worse for audio is like saying all audio transformers are bad, when in fact some of them are bad and some of them are good. It depends on how well they are designed and made.

The truth is that some high gain opamps are notoriously unstable and some, like the 990, are very stable and exhibit no overshoot, ringing, or oscillations. IMHO the stable ones sound much better.

I have no beef with your preference for lower gain opamps. You're welcome to that preference with my blessings. My desire in responding on this forum is hopefully to help those who read it distinguish between preferences and facts.

Best wishes,

[ToneLux]

I'm not going to take this any further becasue it is becoming stupid.

An inductor goes high impedance at high frequencies.

At lower frequencies it is close to a short.

If a resistor is in parallel with an inductor, at low frequencies, the inductor is a short. At high frequencies it is the resistance of the resistor.

If the gain of a stage is dependent on a resistor and you short the resistor out, the gain will be higher. If you switch over from the resistor to an inductor, the lower frequencies will get shorted out and the higher frequencies will be set by the resistor that takes ove when the inductor goes to a higher impedance than the resistor.

The input stage has higher gain at lower frequencies and lower gain at higher frequencies. The inductors set the gain for the lower frequencies and the resistors set the gain for the higher frequencies.

Just STOP already.

[ToneLux]

I'm not going to take this any further becasue it is becoming stupid.

An inductor goes high impedance at high frequencies.

At lower frequencies it is close to a short.

If a resistor is in parallel with an inductor, at low frequencies, the inductor is a short. At high frequencies it is the resistance of the resistor.

If the gain of a stage is dependent on a resistor and you short the resistor out, the gain will be higher. If you switch over from the resistor to an inductor, the lower frequencies will get shorted out and the higher frequencies will be set by the resistor that takes over when the inductor goes to a higher impedance than the resistor.

The input stage has higher gain at lower frequencies and lower gain at higher frequencies. The inductors set the gain for the lower frequencies and the resistors set the gain for the higher frequencies.

Just STOP already.

[ToneLux]

I'm not going to take this any further becasue it is becoming stupid.

An inductor goes high impedance at high frequencies.

At lower frequencies it is close to a short.

If a resistor is in parallel with an inductor, at low frequencies, the inductor is a short. At high frequencies it is the resistance of the resistor.

If the gain of a stage is dependent on a resistor and you short the resistor out, the gain will be higher. If you switch over from the resistor to an inductor, the lower frequencies will get shorted out and the higher frequencies will be set by the resistor that takes over when the inductor goes to a higher impedance than the resistor.

The input stage has higher gain at lower frequencies and lower gain at higher frequencies. The inductors set the gain for the lower frequencies and the resistors set the gain for the higher frequencies.

Just STOP already.

[TheSoundSteward]

Originally posted by Mr. Fancy Pans
Regarding my comments of Deanne Jensen, I met no disrespect at all. I spoke out of turn, what was told to me by one of the early Quad Eight engineers I interviewed for this article. Since then several engineers have called me to set the record straight on this particular individual.
...
This is part of the reason this article is taking so long, trying to get the facts straight and debunk the fiction.
...
I now have 5 different individuals (who were there) proofing this article prior to me sending it in.

Larry DeVivo

Mr. DeVivo,

My opinion of you has gone way, way up as a result of your recent post. Thank you for explaining that you were depending on an unreliable source for your information about Deane and the 990. I admire your desire to get to the truth, and history is often hard to reconstruct accurately. My hat is off to your efforts to get it right.

I believe Deane would say, "Apology totally and respectfully accepted!"

High regards,

[Rader Ranch]

Originally posted by ToneLux
I'm not going to take this any further becasue it is becoming stupid.....
Just STOP already.

to this lurker is seems you're the overly sensitive crotchety old bastard doing all the flipping out !??! maybe grab a couple brews for yourself....

[ToneLux]

Originally posted by Rader Ranch
to this lurker is seems you're the overly sensitive crotchety old bastard doing all the flipping out !??! maybe grab a couple brews for yourself....

Actually, I have had 2 beers already, but get bored and annoyed when people say the same thing I said, but in a different order and tell me I don't get it. and after a few more beers,

[Rader Ranch]

ahh, in that case, lose the beers and go for the stash....

[ToneLux]

Originally posted by Rader Ranch
ahh, in that case, lose the beers and go for the stash....

As every one should... where's my beer

[BrianK]

Let's see if I got this thread right -

Quad Eight made mixer boards, old ones, but they came from some other company that also made them, so they stole the blueprints and everyone was happy. The mixers were good because some guy named "Don Johnson" invented the transformer, which he put in them to make them have sound.

Then he met some X-Files guy from the government who gave him the secret Preamp plans - the 990 (like 666 upside down, but modified). They had so much gain that studios no longer needed power amps. He put these right into the boards, but also put some choke coils (from old wah wahs he had around) into them so that they had better EQ. But he knew they didn't work that way. He even wrote a paper on it to cover himself.

Later he became several other companies, making film consoles for studios on the West Coast (only). And then "Quad Eight" changed and became "Five Point One" which is now famous as "the good sound" all over the world...

[ToneLux]

Exactly

[wwittman]

To come back to Quad Eight...
it somewhat depends what one WANTS from a desk.

I mean, if I push up the fader and things sound terrific to me, more often than not, I tend to be rather happy.

If in fact, the desk is 'helping' that, rather than being more "accurate", that's fine with me.
People like records that sound great more than 'accurate' representations of less exciting sounds.

of course this is a massively pointless exageration... cool innit?

so, MY experience (limited, admittedly) was disappointing.
it certainly was not a BAD desk by any means (we can discuss MCI's of any and every generation later <g>)
Similar to my experience with the Spectrasonics that Record Plant had, I thought it was unquestionably clean and had quality.. but was somehow, subtley, intangibly boring.
Lackluster.
Everytime I brought up the fader on an A Range or an API or some Neves I smiled.
Not true with Quad Eights.

and someone should STILL buy my noise gates! <g>

[ToneLux]

In the beginning, there were hot lumps. The lums were very "mono". Then, they discovered that the heat they generated caused life. The tube was born. Then they started glueing silicon together to make breast implants and they did what they were to do. Amplify. The tube went by the wayside as the new "solid state" became the thing. Then, the lumps made recording devices with "inputs". As the inputs grew in size, they tried to store them in boxes, but the boxes were too small, to they taped many together. They found that the sound actually was sticking to the tape to they put the tape on rolls. Soon after, the "old" tube stuff started to sell for lots of money, causing many to start making the heaters again, and there were many choices. When they ran out of sticky stuff for the tape, the sounds started coming off and had to be cooked back on in ovens, so they started storing the sound on disks. They would chop up the sounds in small pieces and store them. As the knives became sharper, the pieces became smaller and there were more of them. They needed bigger "disks" to store them in so the disks started getting bigger and cheaper. Then someone started hiding all the consoles in small computer cases, but they had to take out a lot of the parts that weighed a lot, and although they were able to store and operate the sounds, the sounds sounded different and unpleasing. This caused a revolt in the industry and the record companies invented rap to fill in the holes, but then started to implode and dissolve. Then Fredrick Atonalot discovered the MP3 format and the record companied cornholed him to death, but a new medium was born and started flying around the "internet" and all the little bands, and big ones too started making money again, and more than they ever did because the big record companies were'nt spending it on limo's. Then out of the blue, Paul quits API and starts Tonelux, and the genetic re-assembly of tone began. All the original member of the Audio Underground ate Thai food in San Francisco and Paul was so happy that he bought dinner. Now, music is fun and all the little tubes and transistors are dancing again just in time for Christmas.

Have you been good?

[De chromium cob]

I want some of what Paul's smokin' for xmas!

[ToneLux]

Originally posted by De chromium cob
I want some of what Paul's smokin' for xmas!

Actually, I was inspired by BrianK, who got the op-amp thing dead on. I was hoping that someone would actually pay attention and learn something from my rant.

This was done straight, so you know what my family has to put up with on a daily basis...

By the way, Chromium is one thing I wouldn't make into a cob, because it is a heavy metal...

[Slipperman]

Originally posted by ToneLux
In the beginning, there were hot lumps. The lums were very "mono". Then, they discovered that the heat they generated caused life. The tube was born. Then they started glueing silicon together to make breast implants and they did what they were to do. Amplify. The tube went by the wayside as the new "solid state" became the thing. Then, the lumps made recording devices with "inputs". As the inputs grew in size, they tried to store them in boxes, but the boxes were too small, to they taped many together. They found that the sound actually was sticking to the tape to they put the tape on rolls. Soon after, the "old" tube stuff started to sell for lots of money, causing many to start making the heaters again, and there were many choices. When they ran out of sticky stuff for the tape, the sounds started coming off and had to be cooked back on in ovens, so they started storing the sound on disks. They would chop up the sounds in small pieces and store them. As the knives became sharper, the pieces became smaller and there were more of them. They needed bigger "disks" to store them in so the disks started getting bigger and cheaper. Then someone started hiding all the consoles in small computer cases, but they had to take out a lot of the parts that weighed a lot, and although they were able to store and operate the sounds, the sounds sounded different and unpleasing. This caused a revolt in the industry and the record companies invented rap to fill in the holes, but then started to implode and dissolve. Then Fredrick Atonalot discovered the MP3 format and the record companied cornholed him to death, but a new medium was born and started flying around the "internet" and all the little bands, and big ones too started making money again, and more than they ever did because the big record companies were'nt spending it on limo's. Then out of the blue, Paul quits API and starts Tonelux, and the genetic re-assembly of tone began. All the original member of the Audio Underground ate Thai food in San Francisco and Paul was so happy that he bought dinner. Now, music is fun and all the little tubes and transistors are dancing again just in time for Christmas.

Have you been good?

After seeing this post, I am seriously considering selling everything and replacing it with WHATEVER Tone-Lux manufactures.

Shoes.

Lawn Darts.

Shower radios.

Recording Consoles.


Whatever.


Hilariously sick.


Very comforting to know that others have been arriving from our planet for many decades now.


SM.

[ToneLux]

But, have you been good?

[dov]

so how does the am-10 fit into this story?
who designed it and is based on the 990?

thanks
dov

[nosebleedaudio]

Originally Posted by ToneLux

The history of all these companies in those days were all intermixed. The Mecore guys then to the API guys, some split and went on with Quad 8, then to this and that. The real question is if the Melcore guys brought the 2520 to API, or were they fired for sexual harrassment and had to find other jobs and didn't know how the 2520 worked? Were the guys that left API and went to Q8 a good thing or a bad thing, or were they draftsmen or test guys? Did Dean ever see an op-amp design before the 990 or did he wake up one morning and say "i'm going to change the world". Did Rupert design the discrete op-amp or did one of his engineers? Did I really invent Post-its? Who invented the Pan pot? Was it the guy who left company A and right after he joined company B they came out with it? Coinsedence or Conspiracy? Maybe one of them was actually on the grassy noll. I heard that one of the guys from Mackey was the photographer that took the original fake movies from Area 51 during the moon landing...

We should construct a family tree at one of the AES shows, and let anyone come by and add to it. That would be fun. Of course, we may find out that they all came from one place in the beginning...

But, it still wouldn't answer the questions of when and where the technology was passed on or invented from. This will always remain a secret, and maybe it is best that way, because some of the best around didn't really invent anything, they just empowered others to do their best and to reach inside their hearts and come up with something that they thought was "better".

Now I want to buy everyone a little puppy.

We all stand on the shoulders of Giants...I don't care who we are, someone before us made it possible for us to design, build ect what ever, from the guy who invented the transistor and before him the guy who discovered Silicon ect ect...

[ToneLux]

Originally Posted by nosebleedaudio

We all stand on the shoulders of Giants...I don't care who we are, someone before us made it possible for us to design, build ect what ever, from the guy who invented the transistor and before him the guy who discovered Silicon ect ect...

I just wonder if the real use of silicon was for implants or the transistor...

[Orphan Audio]

This is my first post here, although I have been reading for years.
I am amused and gratified to find the industy is still filled with engineers of such passion and conviction.

This thread has provided the most entertainment I have had in years.

I have to disagree slightly with Pauls statement (quite some way back in this thread) that the Quad Eight gear did not compare in quality to its competition and as such was discarded by the industry.

More likely is that QE was engaged so strongly and successfully in the film and tv post business, and was so outnumbered by API and others in the music business, that the few custom music consoles that QE built did not make the same impression that the far more prevalent API,s did.
Lets face it, API did a hell of a job selling their product to their market and they deserve their reputation because the gear performed as advertised. If QE had been more agressive and courted the music market as strongly, with a comparable product to the API line, the balance of power might be somewhat different today and we might be valuing the QE stuff as highly as API.
Add to this, the fact that the preferred mode of disposal of a retired post production console is tipping it into a dumpster, and most of those consoles were 15 to 27 feet in length, there was little opportunity to pass those classics on the the next generation and educate them about how cool they were. Classic API and similar desks are still passed down from person to person to this day. But every once in a while I see API gear being pushed onto the scrap heap by a local tv station or film studio, and I grab it as fast as any QE, ADM, WBS, Neve, Langevin, Electrodyne or Sphere gear suffering the same fate.

The QE gear did,nt suck, it just missed the opportunity to outlast the passing of time in the same manner as others who targeted the same market as API.
Does Sphere or Helios suck just because they did'nt sell as many consoles or last as long as API? Probably not.
The music industry is geared to produce hero,s and consoles are no exception. API has rock star status.
But ask anyone who owns one of the QE consoles specifically marketed to the music industry (Coronado, Ventura, Pacifica) about how much they like their classic? You will find they value and rave about it as much as anyone who might be lucky enough to own an equivalent API or Neve. Or talk to one of the many film mixers who has posted hundreds of box office busting films on a QE film console about their fond memories.


Understand I am not looking to start another "Spirited Discussion" or faulting Paul for anything he has stated, just putting forth the opinion that placing a good product in front of a majority of people will simply make it more popular and respected than another equally qualified one with far less exposure.

Ken Hirsch / Orphan Audio , Quad Eight Electronics LLC
www.orphanaudio.com
www.quadeightelectronics.com


"Knowledge is free,.... It,s what you do with it that gets expensive"