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Twin Servo DIY Mic Preamp beside SCA?
Old 13th September 2012
  #1
Twin Servo DIY Mic Preamp beside SCA?

SCA is not willing to sell their kits without transformers and their 990 op-amp. I'd like to build their J99 preamp but I don't want to use the transformer they provide, I'd prefer to use Jensen's and Hardy 990's.

Is there another Twin Servo kit out there that doesn't force you to buy the transformers/op-amps?
Old 17th September 2012
  #2
Old 18th September 2012
  #3
Gear Head
 
🎧 10 years
How much gain do you need?

If 60db is enough, the M1 is a much simpler build. John Hardy posted somewhere (groupdiy? search there) confirming that the M1 sounds essentially identical to the Hardy Twin Servo, but with less gain.

The M1 is essentially a 312 card with a 1:2 Jensen JT-16-B input transformer and 990 DOA. There are also a few board-level component changes to compensate for the 990 op amp. I think you could build it with a common 312 PCB.

The Twin Servo, being a dual stage design, is more complicated to implement.
Old 18th September 2012
  #4
Gear Head
 
🎧 10 years
John Hardy is very generous online with his knowledge and time. There are posts of his around, both here and at prodigypro. Maybe he'll swing by.
Old 18th September 2012
  #5
Gear Maniac
 
🎧 15 years
Quote:
If 60db is enough, the M1 is a much simpler build. John Hardy posted somewhere (groupdiy? search there) confirming that the M1 sounds essentially identical to the Hardy Twin Servo, but with less gain.
That comment is a bit unclear to me. Could you elaborate on what I supposedly posted? (essentially identical, but with less gain....)

By the way, it is correctly known as the "Jensen Twin Servo 990 Mic Preamp", built by the John Hardy Company. "Hardy Twin Servo" might be OK for a short-hand reference, I suppose, but the credit for the circuit belongs to Deane Jensen.

Quote:
The M1 is essentially a 312 card with a 1:2 Jensen JT-16-B input transformer and 990 DOA. There are also a few board-level component changes to compensate for the 990 op amp.
As long as you realize that "a few board-level component changes" include a DC-Servo circuit, input bias current compensation circuitry, no coupling capacitors, tons more power supply filter capacitance, a superior output transformer - Jensen JT-11-BM (yes, it's an option, but virtually everyone gets it), etc.

Quote:
I think you could build it with a common 312 PCB.
If you were Spock. (OK, it's possible, but a LOT of grafting would have to be done, with lots of parts hanging on all over the place)

Quote:
The Twin Servo, being a dual stage design, is more complicated to implement.
Yeah, you would need two 312 cards...

John Hardy
The John Hardy Company
The John Hardy Co. Home
Old 18th September 2012 | Show parent
  #6
Gear Head
 
🎧 10 years
Quote:
Originally Posted by John Hardy ➑️
That comment is a bit unclear to me. Could you elaborate on what I supposedly posted? (essentially identical, but with less gain....)

By the way, it is correctly known as the "Jensen Twin Servo 990 Mic Preamp", built by the John Hardy Company. "Hardy Twin Servo" might be OK for a short-hand reference, I suppose, but the credit for the circuit belongs to Deane Jensen.


As long as you realize that "a few board-level component changes" include a DC-Servo circuit, input bias current compensation circuitry, no coupling capacitors, tons more power supply filter capacitance, a superior output transformer - Jensen JT-11-BM (yes, it's an option, but virtually everyone gets it), etc.


If you were Spock. (OK, it's possible, but a LOT of grafting would have to be done, with lots of parts hanging on all over the place)


Yeah, you would need two 312 cards...

John Hardy
The John Hardy Company
The John Hardy Co. Home
Thanks for the clarification.

I haven't attempted a Jensen-style build--by all accounts, it appears more complicated than a straight 312. It certainly won't be paint by numbers like SCA. There's more information at prodigy pro, much of it from Mr. Hardy himself. I'm the kind of person to attempt it as a learning experience, but if you're not up for it and you don't want to go the SCA route, Mr. Hardy's Beatlejuice-quick appearance is all the more reason to give him your business.

PS I must have been thinking of this post. Mine was a bastardized summary --what I took away from it, correct me if I'm misinterpreting, is that the M1 can be used in much the same way as the Dual Servo, to much the same effect, with the most noticeable difference at high gain levels.
Old 18th September 2012
  #7
Gear Maniac
 
🎧 15 years
Quote:
PS I must have been thinking of this post. Mine was a bastardized summary --
It was the bastardization that was not making sense to me. My original post as referenced above should be self explanatory.

Thank you.

John Hardy
The John Hardy Co.
The John Hardy Co. Home
Old 18th September 2012
  #8
Lives for gear
 
🎧 5 years
Some guy that.




Henk
Old 18th September 2012
  #9
John, thank you for contributing. I get to use your M-1 preamps a lot; I work at Jack Clement and Mark Howard's studios regularly and I'd say 80% of what's recorded at those studios goes through your preamps.

I think the SCA is as close as I'm going to get...maybe I can sell the Cinemag and Lundhall transformers and put that towards the Jensen's...
Old 18th September 2012
  #10
Gear Maniac
 
🎧 15 years
Sean;

There are 12 channels of M-1 at Clementvision. As you probably know, they had a major fire there, and the M-1 preamps sustained a fair amount of damage. We completely overhauled them and they look and work like new.




Higher resolution images are available. Thanks.

John Hardy
The John Hardy Co.
The John Hardy Co. Home
Old 18th September 2012
  #11
Hey John,

Have you seen any picture of the studio since the rebuild?

If not, I'll see if I can get some from a session there last week. We had a great band for Johnny Rodriquez. Mark Howard, David Briggs, Guthrie Trapp, Matt Sweeney, Joey Miskulin and Patrick Keeler.
Old 18th September 2012 | Show parent
  #12
Lives for gear
 
ddageek's Avatar
 
🎧 15 years
Quote:
Originally Posted by John Hardy ➑️
Sean;

There are 12 channels of M-1 at Clementvision. As you probably know, they had a major fire there, and the M-1 preamps sustained a fair amount of damage. We completely overhauled them and they look and work like new.




Higher resolution images are available. Thanks.

John Hardy
The John Hardy Co.
The John Hardy Co. Home
Dang John
I feel a kinship with those poor M1s !
I bet you charged less than it cost to rebuild this burnt body!

Also are you still planning on a 500 series M-1?
Old 18th September 2012
  #13
Gear Maniac
 
🎧 15 years
Eric;

Quote:
Dang John
I feel a kinship with those poor M1s !
I bet you charged less than it cost to rebuild this burnt body!

Also are you still planning on a 500 series M-1?
So you've had some rebuilding of your own! Best of luck with that.

We spent quite a bit of time cleaning things up inside the Clementvision M-1s. Fortunately, the front panel served as a firewall, so things were not TOO bad inside.

I'm still working on the 500 series. A variation of the Jensen Twin Servo wil be first. Any day now. Then the M-1 and M-2 variations.

Thanks very much.

John Hardy
The John Hardy Co.
The John Hardy Co. Home
Old 18th September 2012
  #14
Gear Maniac
 
🎧 15 years
Sean;

Quote:
Have you seen any picture of the studio since the rebuild?

If not, I'll see if I can get some from a session there last week. We had a great band for Johnny Rodriquez. Mark Howard, David Briggs, Guthrie Trapp, Matt Sweeney, Joey Miskulin and Patrick Keeler.
I have one photo from Brooks Watson, showing the equipment rack that held the three M-1 preamps and some other things, immediately after the fire. Ashes and other crap everywhere.

Sounds like you had quite a session there. I will get down there one of these days, after I catch up with a few things.

I would love to see the "before" and "after" shots.

Thanks.

John Hardy
The John Hardy Co.
The John Hardy Co. Home
Old 18th September 2012
  #15
It was very sad after the fire, seeing the ashes from the grand piano and plate reverb and burnt up tape reels piled up in the back yard.

But, now the house is nicer than it ever was.

I'll be sure to get them for you. Mark did a really nice job designing the studio. I wired a lot of it up, building the mic panel and doing the Cat 5 runs for the headphone system. A small rule in a big project. Soldering a hundred or so XLRs wasn't the enjoyable way to spend a week, but I enjoy being over there.
Old 19th September 2012
  #16
Gear Maniac
 
🎧 15 years
Here is the picture that Brooks Watson sent to me. Three M-1 mic preamps in the rack with various other items.



John Hardy
Old 19th September 2012
  #17
I think your Hardy's are the only thing that was saved.

Here's a rather blurry picture from the studio.



Top (Left to Right): Guthrie Trapp, Me!, David Briggs, Mark Howard Patrick Keeler, David Ferguson, Dave Roe
Middle (Left to Right): Johnny Rodriquez, Cowboy Jack, Joey Miskulin
Bottom: Matt Sweeney

There are some legends in the picture and is a great pleasure to work with all of them
Old 19th September 2012
  #18
Lives for gear
 
nosebleedaudio's Avatar
 
🎧 15 years
Calling it the Jensen Twin Servo with NO Jensen input trans...
Lundahl gives VERY little info about their transformers..Also not the same Ratio as the Jensen..
Save up...
Old 19th September 2012 | Show parent
  #19
Lives for gear
 
hasbeen's Avatar
 
1 Review written
🎧 15 years
Quote:
Originally Posted by John Hardy ➑️
I'm still working on the 500 series. A variation of the Jensen Twin Servo wil be first. Any day now. Then the M-1 and M-2 variations.
Very excited to get one of these! Thanks for the heads up. Any ballpark figures for a cost?
Old 19th September 2012
  #20
I originally intended on building a pair of these:

312 Hybrid PCB

Which are pretty close to a M1. But, Bob is out of boards and isn't planning on making more.

Michael, you are right about SCA kit. I think I'm going to build some T-15's...that's a pretty good design around the THAT 1510. And cheap. I haven't found an 8 channel unit for less...except this new Five Fish Audio 8 channel preamp that's not out yet...not a lot of details but I'm interested!
Old 19th September 2012 | Show parent
  #21
Gear Guru
 
kafka's Avatar
 
🎧 10 years
Quote:
Originally Posted by John Hardy ➑️
I'm still working on the 500 series. A variation of the Jensen Twin Servo wil be first. Any day now. Then the M-1 and M-2 variations.
Looking forward to it.
Old 19th September 2012
  #22
Gear Maniac
 
🎧 15 years
Sean;

I don't see a picture. Please try posting it again. I would love to see it. Thanks.

John
Old 20th September 2012
  #23
There you go John.
Old 20th September 2012 | Show parent
  #24
Gear Head
 
🎧 10 years
Quote:
Originally Posted by Sean Sullivan ➑️
I think your Hardy's are the only thing that was saved.

Here's a rather blurry picture from the studio.



Top (Left to Right): Guthrie Trapp, Me!, David Briggs, Mark Howard Patrick Keeler, David Ferguson, Dave Roe
Middle (Left to Right): Johnny Rodriquez, Cowboy Jack, Joey Miskulin
Bottom: Matt Sweeney

There are some legends in the picture and is a great pleasure to work with all of them
Matt Sweeney! The album he did with Will Oldham and the two Chavez albums are incredible. Seriously one of the best guitarists.
Old 20th September 2012
  #25
He produced Anna Ternheim's "The Night Visitor" and plays guitar on that album. Every song started out with the two of them playing acoustic guitar live and we built the songs around that. That was a fun album to be a part of.

Will and Matt also did a 10" with us for Drag City called "I Must Be Blind" as Superwolf.

We just finished up a new album with Will last week...so look for that too! Matt plays guitar on a few tracks.

Matt is a regular in Nashville these days...
Old 20th September 2012
  #26
Gear Maniac
 
🎧 15 years
Strange as it may seem, I still do not see a picture. Is anyone else not seeing it? Thanks!

John
Old 20th September 2012
  #27
Lives for gear
 
Slikjmuzik's Avatar
 
🎧 10 years
I don't either...
Old 20th September 2012
  #28
Ok, I used a different image hosting site.
Old 20th September 2012
  #29
Gear Maniac
 
🎧 15 years
Still no picture.
Old 20th September 2012
  #30
Gear Maniac
 
🎧 15 years
OOPS! Correction: I see it, back in the original message. Sorry for the confusion.

John
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