elskardio

Twin Servo Mic Preamp for 500 series
« on: September 18, 2019, 12:46:18 PM »
Hi Guys,

I just wanted to share my latest project. It's my take on the Jensen Twin Servo for the 500 series format.
I'm using Cinemag transformers at the Input & Output.
The discrete opamps are my version of the 990.
So far this is my favourite mic preamp. A lot of clean gain and well balanced over the frequency range.

Cheers
Gabriel


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Just to clarify... I won't be offering kits anytime soon. I have too much work at the moment and I still need to test the latest revision with the trim control.

Thanks


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I'm also working on a Revision with a variable Trim control (10dB of range).

Mockup of the TS-990 with Trim:



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Update November 4:

Here's the latest revision with bias adjustment for the discrete opamps and pcb footprint for Jensen transformers.



« Last Edit: February 06, 2020, 12:12:39 PM by elskardio »


Ricardus

Re: Twin Servo Mic Preamp for 500 series
« Reply #1 on: September 18, 2019, 01:13:40 PM »
Pics, schematic, pencil drawing, something?

  ;D
Audio mastering for hire..

elskardio

Re: Twin Servo Mic Preamp for 500 series
« Reply #2 on: September 18, 2019, 01:42:49 PM »
Pics, schematic, pencil drawing, something?

  ;D

There’s 2 pictures in the first post... let me know if it loads fine.

Fuzz Face

Re: Twin Servo Mic Preamp for 500 series
« Reply #3 on: September 18, 2019, 02:40:02 PM »
There’s 2 pictures in the first post... let me know if it loads fine.
It loaded fine for me and looks FANTASTIC. Impressive work

Re: Twin Servo Mic Preamp for 500 series
« Reply #4 on: September 18, 2019, 02:41:42 PM »
Yeah, that looks pretty amazing. Any thoughts on kits/pricing as of yet? I'm super intrigued.

Fuzz Face

Re: Twin Servo Mic Preamp for 500 series
« Reply #5 on: September 18, 2019, 02:59:56 PM »
I’d be interested in one as well

Ricardus

Re: Twin Servo Mic Preamp for 500 series
« Reply #6 on: September 18, 2019, 05:07:13 PM »
There’s 2 pictures in the first post... let me know if it loads fine.

I am not seeing any pics in that post. I'm on Chrome. Lemme check with my phone.
Audio mastering for hire..

Ricardus

Re: Twin Servo Mic Preamp for 500 series
« Reply #7 on: September 18, 2019, 05:10:43 PM »
Chrome on my phone shows them, but not on my laptop.

Firefox shows them.

Weird.
Audio mastering for hire..

elskardio

Re: Twin Servo Mic Preamp for 500 series
« Reply #8 on: September 19, 2019, 01:08:29 PM »
Yeah, that looks pretty amazing. Any thoughts on kits/pricing as of yet? I'm super intrigued.

I'm not planning to sell kits at the moment... But if there's enough interest I could probably do a small batch  ;)

Re: Twin Servo Mic Preamp for 500 series
« Reply #9 on: September 19, 2019, 03:04:26 PM »
Count me as interested, then.


Ricardus

Re: Twin Servo Mic Preamp for 500 series
« Reply #10 on: September 20, 2019, 01:25:13 AM »
I'm interested too.
Audio mastering for hire..

3nity

Re: Twin Servo Mic Preamp for 500 series
« Reply #11 on: September 22, 2019, 11:23:00 AM »
Looks great.
At one point i did had a couple of prototypes done but never made it past there... I love their 3d type of sound.
Good luck
Life is a path, death the destination.

elskardio

Re: Twin Servo Mic Preamp for 500 series
« Reply #12 on: September 25, 2019, 10:33:15 AM »
Looks great.
At one point i did had a couple of prototypes done but never made it past there... I love their 3d type of sound.
Good luck

Thanks 3nity
The grounding scheme  is a bit tricky with this one... I made 3 prototypes before everything was 100% stable, even at extreme gain settings.
I just ordered the final PCB revision. I added Bias adjustments for the discrete opamps to help the servo work faster. I also added footprint for Jensen transformers.
I'll post pictures when it's assembled in 1-2 weeks.
Cheers

Re: Twin Servo Mic Preamp for 500 series
« Reply #13 on: October 22, 2019, 08:39:36 AM »
I’m interested in kits too...

elskardio

Re: Twin Servo Mic Preamp for 500 series
« Reply #14 on: October 22, 2019, 09:59:46 AM »
I might do a small batch of kits by the end of the year...

I have the latest revision in intensive test at 2 different studios. So far everyone's loving them.  8)

I'm also testing different flavour of discrete opamps


Fuzz Face

Re: Twin Servo Mic Preamp for 500 series
« Reply #15 on: October 24, 2019, 07:36:52 PM »
This is a beautiful build. I’d love to build a pair. Even if you don’t do a “kit”, I’d be interested in the PCBs

Re: Twin Servo Mic Preamp for 500 series
« Reply #16 on: October 24, 2019, 09:23:07 PM »
I'm still very interested in a kit.

Have you tried a version of the OA10 op amp? I just put a pair of Gary Bennett's new OA10's in a Hairball Lola and they really sound great. Adds a wee bit of bite that the Hardy 990s don't have. So, as such I have a pair of Hardy 990c's sitting around just waiting for a preamp to be put into...

elskardio

Re: Twin Servo Mic Preamp for 500 series
« Reply #17 on: November 04, 2019, 07:47:21 PM »
Hi guys,

I updated the first post pictures. This is the latest revision with bias adjustments for the discrete opamps and pcb footprint for Jensen transformers.

I could probably make a few partial kits available before Christmas.

If you're interested, please post the following details:

- Your username
- How many kits?
- Planning to use the CA-990? or another DOA?
- Would you like to have transformers included in the kit?

Cheers

Ricardus

Re: Twin Servo Mic Preamp for 500 series
« Reply #18 on: November 04, 2019, 08:21:09 PM »
Hi guys,

I updated the first post pictures. This is the latest revision with bias adjustments for the discrete opamps and pcb footprint for Jensen transformers.

I could probably make a few partial kits available before Christmas.

If you're interested, please post the following details:

- Your username
- How many kits?
- Planning to use the CA-990? or another DOA?
- Would you like to have transformers included in the kit?

Cheers

Ricardus
I would be interested in 2 kits after Xmas. Money will be too tight before Xmas.
I would probably use a different Op-Amp, but would want transformers.
« Last Edit: November 05, 2019, 10:02:31 PM by Ricardus »
Audio mastering for hire..

Fuzz Face

Re: Twin Servo Mic Preamp for 500 series
« Reply #19 on: November 04, 2019, 09:15:32 PM »
Hi guys,

I updated the first post pictures. This is the latest revision with bias adjustments for the discrete opamps and pcb footprint for Jensen transformers.

I could probably make a few partial kits available before Christmas.

If you're interested, please post the following details:

- Your username
- How many kits?
- Planning to use the CA-990? or another DOA?
- Would you like to have transformers included in the kit?

Cheers
Fuzz Face
2 kits
CA-990
Transformers yes


 

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