dustbro

Re: SSL 4K G-Series Mic Preamp
« Reply #20 on: February 04, 2017, 08:11:04 PM »
PCB's are on the way. Anyone want to volunteer for beta testing?


Potato Cakes

Re: SSL 4K G-Series Mic Preamp
« Reply #21 on: February 04, 2017, 09:29:16 PM »
I'd be interested in being a guinea pig.

Thanks!

Paul

totoxraymond

Re: SSL 4K G-Series Mic Preamp
« Reply #22 on: February 05, 2017, 02:46:54 AM »
I volunteer too.

Thomas

Whoops

Re: SSL 4K G-Series Mic Preamp
« Reply #23 on: February 05, 2017, 11:51:11 AM »
I also volunteer to test the pcb's and circuit.

Thank for you work Dust Bro

Martin Griffith

Re: SSL 4K G-Series Mic Preamp
« Reply #24 on: February 12, 2017, 01:32:33 PM »
What are you using for the input transistors? LM394's are quite obsolete. A quick search shows the Mat03 is on Last Time Buy at Digikey

Pusch3l

Re: SSL 4K G-Series Mic Preamp
« Reply #25 on: February 12, 2017, 03:14:17 PM »
Interesting Project. If you have a volunteer slot available i would be happy for testing.

dustbro

Re: SSL 4K G-Series Mic Preamp
« Reply #26 on: February 13, 2017, 11:34:31 AM »
Thanks guys! I'll let everyone know when prototype boards are available.
PM me your mailing addresses.

dustbro

Re: SSL 4K G-Series Mic Preamp
« Reply #27 on: February 13, 2017, 11:36:50 AM »
What are you using for the input transistors? LM394's are quite obsolete. A quick search shows the Mat03 is on Last Time Buy at Digikey
EBay seems to have a sufficient supply.

Potato Cakes

Re: SSL 4K G-Series Mic Preamp
« Reply #28 on: February 13, 2017, 12:39:38 PM »
EBay seems to have a sufficient supply.

There is an older thread regarding replacing the LM394 and someone used 2 OPA2604's in its place with great results supposedly. However, I didn't see any data posted to support this. But dustbro is right, there are plenty LM394s on eBay.

Thanks!

Paul

abbey road d enfer

Re: SSL 4K G-Series Mic Preamp
« Reply #29 on: February 13, 2017, 01:11:27 PM »
There is an older thread regarding replacing the LM394 and someone used 2 OPA2604's in its place with great results supposedly.
Supposedly is the word. I don't see how a BiFET opamp with 10nV/sqrtHz noise voltage can replace an LM394 with 10 times less.


Quote
  But dustbro is right, there are plenty LM394s on eBay.
I would be very cautious about possible counterfeits, though.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.


Potato Cakes

Re: SSL 4K G-Series Mic Preamp
« Reply #30 on: February 13, 2017, 01:35:28 PM »
Supposedly is the word. I don't see how a BiFET opamp with 10nV/sqrtHz noise voltage can replace an LM394 with 10 times less.

 I would be very cautious about possible counterfeits, though.

Indeed, caution is necessary with buying NOS transistors/ICs on the eBay.

When the prototype boards show I will try the dual 2604 option after it's working with LM394s.

Thanks!

Paul

Whoops

Re: SSL 4K G-Series Mic Preamp
« Reply #31 on: February 13, 2017, 04:41:15 PM »
You can use MAT02EH instead of the LM394,  it has better specs actually.

I buy MAT02EH from this source, fast shipping and never had a problem:

mary
Aosiwei Electronics Co.,Ltd
 
Tel:  +86 -27-82848366                         Fax:     +86-27-82848466

E-mail: [email protected]
MSN: [email protected]     
Website:    www.aosiwei.com

Martin Griffith

Re: SSL 4K G-Series Mic Preamp
« Reply #32 on: February 14, 2017, 04:40:50 PM »
Analog have a few matched pairs http://www.analog.com/en/products/linear-products/matched-transistors.html and I might get some ssm2212 which are not too expensive ( for RS!). I was thinking of the AMEK 2500  with npns maybe the 2n5088. I'm always wary of buying NOS. The Aosiwei Electronics site wouldn't let me search anyway.

dustbro

Re: SSL 4K G-Series Mic Preamp
« Reply #33 on: February 14, 2017, 08:03:51 PM »
I would be very cautious about possible counterfeits, though.

Very true... I just bought a boatload of LF351 from china, and they exploded in my circuit. TL081 worked fine

Pusch3l

Re: SSL 4K G-Series Mic Preamp
« Reply #34 on: February 17, 2017, 03:28:47 AM »
Very true... I just bought a boatload of LF351 from china, and they exploded in my circuit. TL081 worked fine

I think nobody wants such a situation on the first power up..

But i have a question regarding C3 on the phantom power. Is the cap not a bit overrated with 100VDC? I have to admit i just know from some articles that electrolytic caps likes to run at 75% of its max rating. After some basic math (yes i dont have much to do at work...) i ended up with a 63VDC max rating.
Hope i didnt get that wrong ::)

abbey road d enfer

Re: SSL 4K G-Series Mic Preamp
« Reply #35 on: February 17, 2017, 05:21:26 AM »
I have to admit i just know from some articles that electrolytic caps likes to run at 75% of its max rating.
  Who sez? Capacitor ratings are for continuous operation, and tolerate about +15% surges. Useful life of el caps is more dependant on temperature than voltage (as long as it's < than the rated voltage).


Quote
  After some basic math (yes i dont have much to do at work...) i ended up with a 63VDC max rating.
Hope i didnt get that wrong ::)
You're right, 63V is adequate for phantom isolation.
If I had to choose between 63V/105°C and 100V/85°C, I would choose the former.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

Re: SSL 4K G-Series Mic Preamp
« Reply #36 on: February 17, 2017, 07:13:43 AM »
You can use MAT02EH instead of the LM394,  it has better specs actually.

I buy MAT02EH from this source, fast shipping and never had a problem:

mary
Aosiwei Electronics Co.,Ltd
 
Tel:  +86 -27-82848366                         Fax:     +86-27-82848466

E-mail: [email protected]
MSN: [email protected]     
Website:    www.aosiwei.com

Did a business once with that company, and for 5 years she and her colleagues wouldn't stop spamming my inbox.

Pusch3l

Re: SSL 4K G-Series Mic Preamp
« Reply #37 on: February 17, 2017, 01:39:22 PM »
Useful life of el caps is more dependant on temperature than voltage (as long as it's < than the rated voltage).

So i did get that wrong..sorry  :-[

dustbro

Re: SSL 4K G-Series Mic Preamp
« Reply #38 on: February 18, 2017, 02:38:04 PM »
Is the cap not a bit overrated with 100VDC?
Overrated? yes... but I found them cheaper than 63V caps :)

dustbro

Re: SSL 4K G-Series Mic Preamp
« Reply #39 on: February 18, 2017, 02:48:15 PM »
still waiting for the boards to ship. Hopefully soon