DaveP

Presto 41-A
« on: June 12, 2012, 07:38:27 AM »
Came across this compressor in Oliver Read's book.

It must be pre 1952 when his book was published, similar to a Gates SA-39.

It looks fairly conventional, anyone ever heard or had experience of this?


best
DaveP
Soundcloud: Delayed Action.


EmRR

Re: Presto 41-A
« Reply #1 on: June 12, 2012, 10:05:08 AM »
They're pretty rare, and are all the rage because of it.  Sell for a small fortune, it's a contest to see who can own one.   UTC A series audio iron if I remember correctly.  They look awesome on the front.  That's all I know of them. 
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde

letterbeacon

Re: Presto 41-A
« Reply #2 on: June 12, 2012, 10:24:56 AM »
Came across this compressor in Oliver Read's book.
I hope this doesn't derail the thread, but what's the book you're reading?  I Googled 'Oliver Read book' (pretty vague!) but nothing came up...

DaveP

Re: Presto 41-A
« Reply #3 on: June 12, 2012, 12:56:49 PM »
but what's the book you're reading?  I Googled 'Oliver Read book' (pretty vague!) but nothing came up...

Matt,

About a third of the way down the page of this excellent site. 16MB Download.

http://www.tubebooks.org/technical_books_online.htm

"The recording and reproduction of sound" by Oliver Read.

best
DaveP
« Last Edit: June 12, 2012, 03:46:18 PM by DaveP »
Soundcloud: Delayed Action.

DaveP

Re: Presto 41-A
« Reply #4 on: June 12, 2012, 02:25:32 PM »
They're pretty rare, and are all the rage because of it.  Sell for a small fortune, it's a contest to see who can own one.   UTC A series audio iron if I remember correctly.  They look awesome on the front.  That's all I know of them. 

I feel another project coming on!
best
DaveP
Soundcloud: Delayed Action.

EmRR

Re: Presto 41-A
« Reply #5 on: June 12, 2012, 02:34:09 PM »
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde

letterbeacon

Re: Presto 41-A
« Reply #6 on: June 12, 2012, 03:37:53 PM »
About a third of the way down the page of this excellent site. 16MB Download.

"The recording and reproduction of sound" by Oliver Read.

best
DaveP

Do you mean this site?  I can't seem to find it!

I did some searching over on GS - there's one guy on there with 7 of these things!

DaveP

Re: Presto 41-A
« Reply #7 on: June 12, 2012, 03:45:48 PM »
Letterbeacon,

Oops, it didn't paste!

Here we are

http://www.tubebooks.org/technical_books_online.htm

best
DaveP
Soundcloud: Delayed Action.

letterbeacon

Re: Presto 41-A
« Reply #8 on: June 12, 2012, 03:51:06 PM »
Thanks Dave!

alexc

Re: Presto 41-A
« Reply #9 on: June 13, 2012, 03:58:47 AM »
While on the subject of esoteric limiters, have any of you guys seen a Westrex model?

The schematics are in the Audio Cyclopaedia.

Real interesting in that they use tube powered side chain amps with transformers.
Love to know more about them.

Thx
I ping therefore I am


DaveP

Re: Presto 41-A
« Reply #10 on: June 14, 2012, 06:16:10 AM »
Looking at the schematic in detail, the coupling caps to the output tubes are only 0.001uF!
If you remember, the Altec 436 is 0.022uF and this is considered quite a small value.

There is quite a lot of feedback to smooth some of this LF loss, but I wonder how much this compensates, only the Maxson CA1589 has such low value coupling caps, there must have been a thumping issue here, maybe not such a good design after all.

best
DaveP
Soundcloud: Delayed Action.

EmRR

Re: Presto 41-A
« Reply #11 on: June 14, 2012, 09:24:30 AM »
Both are considered to sound magic, not that the Presto should sound anything like the Maxon, but magic in the Maxon = telephone sound. 
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde

DaveP

Re: Presto 41-A
« Reply #12 on: June 14, 2012, 10:31:53 AM »
Ah Ha,

I've just noticed that the Presto is almost a straight copy of a WE 1126A, even the 0.001uF caps.

Only changes are they have dispensed with the  interstage chokes and used 6SJ7's instead of 6J7's.

well well
DaveP
Soundcloud: Delayed Action.

Re: Presto 41-A
« Reply #13 on: June 14, 2012, 12:57:49 PM »
You hear people harping on how great a bass sounds through something like the Federal (truncated response curves).

One way of viewing the magic there = lazy man's special.  Think of all the cutting and EQing you tend to do on modern bass tracks during mixdown .  Box already does it for you !  And maybe adds a dose of distortion from iron not speced to do deep bottom anywhere near cleanly.   When you look at some of the typical preset DAW EQ curves for "bass enhancing"  you see curves that have broad boosting in the 200-3K area, which is essentially what you end up with when using an amplifier with the speech range response. 

DaveP

Re: Presto 41-A
« Reply #14 on: June 14, 2012, 02:08:00 PM »
You hear people harping on how great a bass sounds through something like the Federal (truncated response curves).

  When you look at some of the typical preset DAW EQ curves for "bass enhancing"  you see curves that have broad boosting in the 200-3K area, which is essentially what you end up with when using an amplifier with the speech range response. 

Yes I see what you're saying there and another way to look at it is, that if the amp does not have much bass response then neither does the side chain (which is fed from the amp) so what bass there is does not get compressed as much as the mids and top.  This probably evens things out.

best
DaveP
Soundcloud: Delayed Action.

Recording & Reproduction of Sound
« Reply #15 on: June 27, 2012, 12:35:19 AM »
I have a copy in very good condition, sell for $20.00. Packe with info. on disc cutting & audio recording electronics.

vinyvamos

Re: Presto 41-A
« Reply #16 on: August 09, 2019, 06:37:04 AM »
Old thread exhumation commencing... I am looking into building a comp based around 6L7 tubes and the obvious options are WE1126 and Presto 41a. From your comments here Dave P, did you ever pursue these ideas? I am curious as to whether inserting an interstage trafo would allow for larger coupling caps to be used to the final stage, and eliminate any possible thumping issues that increasing the caps would otherwise cause.

Has anyone successfully built a 6L7-based comp and been happy with it?
Atomic Analog Devices
*************************
Studio Silo - A Tape Studio in East Iceland

DaveP

Re: Presto 41-A
« Reply #17 on: August 09, 2019, 08:22:31 AM »
Hi Vinny,

Probably the best compressor to make with 6L7's is a Gates 39-B, you can follow my build here:-

https://groupdiy.com/index.php?topic=50998.msg647328#msg647328

The advantage of this design is that it does not use an interstage transformer.

DaveP

Soundcloud: Delayed Action.


 

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