Name That Engineer

[NewYorkDave]

If someone wants to share it with a couple of friends via email, that's his business. But I should warn against posting any AES papers publicly--they're under copyright.

 

[CJ]

Larry, I asked Doc Hoyer, not Mr. Sowter. Doc has rewound maybe forty or so 670 control outputs, so I gave you the specs for the original. Says they quit making the endbells, which pisses him off.
The NFB winding is 300 turns of #35 wire, if your curious.

I guess PRR is right. People like popping those outputs.

Rein talked quite a bit about Ampex, and it wasn't pretty. Gross mis-management by admin people, who wouldn't listen to their engineers, and the rest is like the company, history.

He took a 300 tape machine when he was at Gotham and stripped out everything but the transport and made his own amplfiers. Said the originals had too much distortion. Sheesh, talk about DIY!

I will check on that model number. Running the interview thru a Pultec for that "old school" sound!

cj

 

[Larrchild]

Running the interview thru a Pultec for that "old school" sound!

If the peaks are excessive, I could smooth them out with a local 670. =)

 

[CJ]

Rein has a recording out of his field work in the refugee camps. I asked him if he squashed it with a 670, but he said no.

 

[NewYorkDave]

[quote author="CJ"]Gross mis-management by admin people, who wouldn't listen to their engineers[/quote]

That sounds like every job I've ever worked, especially my current job.

 

[Larrchild]

It's a shame they Rein'ed on his parade. They lost a talented cat. Sorry to Poniatificate.

 

[CJ]

Actually, everyone started bailing out, so they made him the boss of the Titanic. He quit it all and went on a long vacation with his family on his 37 foot boat, around Lake Michigan and up and down the rivers. Ampex had him move to Chicago from the west coast, then he ends up bailing out anyway.

 

[SonsOfThunder]

[quote author="CJ"] people, who wouldn't listen to their engineers[/quote]

The only people who listen to engineers...are other engineers. I think its because they can't speak the language maybe. :thumb:

Peace!
Charlie

 

[CJ]

In the Ampex case, Rein and his team had developed a product that was to be aimed at the consumer market. But the admin guys were afraid that it would take away from the more expensive commercial product, so they refused to release it. Sound familiar?
.

.

.

Think IBM.

 

[SSLtech]

I have a 5670 here that I just tweaked and trimmed up. There also a Mercury 66 single channel 'clone' here, too. The limiting action is similar on both units, but I just plotted a couple of Amplitude/frequency sweeps and on the 670 both channels roll off gently, starting about 100Hz, down about 2dB at 20Hz.

For grins, I swept the 66 as well... the response is quite different. unlike the 670 there's no actual flat part of the curve, it's actually tilted upwards slightly across most of the spectrum. the 'peak' is about 3kHz, though the slope is very gentle, down about 1dB evenly all the way down to 20Hz. Above 4kHz, it slopes down about ½dB by 20kHz.

Larry, how does your unit do on amplitude/Freq? I think the iron msy be different in the mercury, haven't looked to see which tues they do it with just yet...

Keith

 

[dylancw]

Mr. Narma may or may not have mentioned this in the discussion, but Fairchild's stereo cutterhead (641?) was Vertical/Lateral, not 45/45 like the westrex, this might explain some of the 670 controls.

 

[SSLtech]

Doesn't matter for the limiter. While the 670 seperates Mid/Side (or lat/vert) for processing, even when this mode is selects, the signal inputs still go in as L/R and are re-converted to L/R for output. it's just about how the limiting is applied to the signal... unless I misunderstand you, which is certainly not impossible! :wink:

Welcome, BTW...! :grin:

Keith

 

[Larrchild]

Larry, how does your unit do on amplitude/Freq? I think the iron msy be different in the mercury, haven't looked to see which tues they do it with just yet...

The Sowter input xfmr actually had flat response past 10k and had a peak at 15k. The original 670 had a compensation trimmer on the secondary, so I added some pf's of "c" and it leveled off.

Low end is level-dependent of course, but down one db @ 20hz sounds about right.

 

[SSLtech]

Egg-sallent, -thanks Larry!

The 670 was looking much healthier when I left yesterday. Both channels exhibiting similar slope, timing and threshold characteristics, unlike previously.

The Mercury -while nothing like the same amplitude/frequency sweep, was commendably similar on the ratio curve, and it appears to use 6V6's.

Keith

 

[Larrchild]

The Hammond 1645 and pair of 6BQ5's is working out great for me here.
I'm getting like 85 volts on the bridge rectifier now. About 35 db of GR too.
And the 4 ohm floating winding is working perfect for a feedback tap.

And the world is full of 6BQ5's =)

Lar'

Regarding curves, I think people would generally want a very transparent path for their main mix to go thru, with the Fairchild compression signature.

The Triads and whatever else Fairchild used were only rated to 15kc and indeed start to roll off and are not transparent by todays' standards.

 

[SSLtech]

Good deal.

I reckon that if your version is all that it can be, I'll certainly recommend a demo the next time someone I know asks for Fairchild type compression!

Keith

 

[NewYorkDave]

So CJ, ya gonna share this interview with the class, or are ya keeping it to yourself? :razz:

 

[CJ]

still transcribing ...
Kayak season winding down ....two weeks left. :sad:

 

[SSLtech]

The Eel river was chilly! -Had to stop off at the Eel River Brewing Company in Eureka for a bit of a swift, restorative snifter afterwards!

Kayaks, Variable Mew and Beer all closely linked, dontcha know! :wink:

Keef

 

[SUPERMAGOO]

Excellent post!
very good story!
I was thinking about using 6V6 instead of 6bq5.
specifications seemed more like those of 6973.