[[silent:arts]]

 

you are in contact with Gustav?
I can't home etche ...

[Matthew Jacobs]

Component layout drawings & copper layer pdf for home etchers published. See the first post in this thread.

Thanks audiox. Thanks very much. I may just give this a try as my first home etch...

I'm thinking of combining this with you other "mastering studer 169 EQ". IIRC you design that circuit with that in mind right?

J

[audiox]

you are in contact with Gustav? I can't home etche ...

Gerber files are ready, but I hope that someone checks the mechanical dimensions first. Most likely they are OK, but better to ensure before manufacturing the boards. Maybe someone involved in the 51X rack project could do that. I think dxf file would be the easiest way...

[[silent:arts]]

Gerber files are ready, but I hope that someone checks the mechanical dimensions first. Most likely they are OK, but better to ensure before manufacturing the boards. Maybe someone involved in the 51X rack project could do that. I think dxf file would be the easiest way...

pm me your email address and I will mail you the outline of Jeffs MicPre in dxf format for comparison.

[audiox]

I will mail you the outline of Jeffs MicPre in dxf format for comparison.

Thanks. Your dwg file opened perfectly...

[jsteiger]

Thanks. Your dwg file opened perfectly...

Good. I hope all was correct for you.

This will be an excellent project. Thanks for all of your hard work audiox! No home etch for me either. I will be looking to buy a few boards. 

[audiox]

Is there a gerber?

Gerber files e-mailed to Gustav.

What has been the practice with the card edge connector contacts on the PCB? Hard gold plating is quite expensive...

[jsteiger]

Gerber files e-mailed to Gustav.

What has been the practice with the card edge connector contacts on the PCB? Hard gold plating is quite expensive...

I do gold fingers on my mic preamp cards, on the bottom side only. Peter Purpose brought up a good idea in his 1084 thread. Only plate the actual used contacts. This will give you 9 for your eq and 10 for a preamp requiring 48V. It's not a huge saving but it all adds up! 

I wish Peter would have thought about this a year ago.

Jeff

[audiox]

I do gold fingers on my mic preamp cards ... Only plate the actual used contacts ...

Could you contact Gustav and explain him the details? I think that would be the best way to ensure that we get the right type of plating with decent price.

[peterc]

These are pins & sockets I use for my DOA stuff, from RS:

434-712 socket
433-860 pins

Regards

One question before creating the Gerber files:
Which is the hole diameter that I should use for the discrete op-amps? The socket pin diameter varies from one manufacturer to another...

[audiox]

I think selectable frequencies for the high and low bands would be a better addition than the mic pre. And would make the eq much more versatile.

I also think Baltimore's suggestion is much better than the preamp addition.. selectable frequencies are always good, if it's easy to do..

Earlier today I had time to think about the frequency selection option. There is actually space enough for two on-off-on miniature toggle switches in the front panel. Not the prettiest solution but could be worse too. Picture attached (you must be logged in to see it).

Only a little manual wiring and you get 3 selectable frequencies which should be enough most purposes. When I designed the board I included some extra pads to make the wiring easier. I will publish some documentation about it when I have time.

- - -

I e-mailed the Gerber files to Gustav 5 days ago. No answer so far... Someone (jsteiger?) could also talk to him about gold finger plating. I have ordered boards with hard gold long time ago and things have probably changed a lot from those days.

[[silent:arts]]

any news on this ...

[audiox]

any news on this ...

I e-mailed Gerber files to Gustav more than a month ago. No answer so far.

A pdf file for home etching can also be found in the first post in this thread. So I guess it is up to you guys...

[dmp]

I'm curious about the Opamp for the balanced output? There might be space on the board to add an option for an output transformer in the upper corner? (Maybe one like EA2623?) If there was room for the cutout (~1.1"x1.3") the builder could do either.
I'm new, maybe someone can shed some light.

[audiox]

Mechanical documents published.

Front panel:
http://docs.google.com/fileview?id=0B_XBYPfmG8pVNWZlNzA1ZjktOTA3ZS00Nzg5LWI2NWMtMzEzMjAyNmEyMjkw&hl=en

Since L bracket is not easy to DIY, I have used a different approach to support the front panel (mounting block made of hexagonal spacer):
http://docs.google.com/fileview?id=0B_XBYPfmG8pVMjVkMDYzNTEtYzdhMS00ZDlkLWJjNWMtZGZjMGFiODAzYTNl&hl=en

[shot]

Silly question... I'm wondering why are potentiometers P2 and P3 (high and mid gain) double 10K lin?
Why not a single 4K7 linear? Shouldn't it perform almost same? (or I don't quite understand it yet...)
Are their pins supposed to be wired oppositely maybe?

 

[audiox]

Silly question... I'm wondering why are potentiometers P2 and P3 (high and mid gain) double 10K lin? Why not a single 4K7 linear?

Dual unit is used for mechanical reasons. (I also noticed that dual 10K is easier to get than single 4K7, which is not available from Audiomaintenance web shop).

[Gustav]

I just wanna say I started a feeler thread on this in the black market, and the files have been sent for fabbing now. It wont take long.

The gold fingers wont add much to the cost. Ill keep the price down. Doing a few less fingers wouldnt change the price - it would add some manual work covering up those areas when doing the gold plating I think.

Gustav

[regularjohn]

I just breadboarded this circuit to try it out and see how it sounds before I go through the process of making a pcb.

I've noticed that the level with the eq switched in and all three boost/cuts at 0 is several dB higher than with the eq bypassed.  Has anyone else had this experience?  Any suggestions for trimming down the level?

It's a great sounding eq otherwise!  

[Snatchman]

I just breadboarded this circuit to try it out and see how it sounds before I go through the process of making a pcb.

I've noticed that the level with the eq switched in and all three boost/cuts at 0 is several dB higher than with the eq bypassed.  Has anyone else had this experience?  Any suggestions for trimming down the level?

It's a great sounding eq otherwise!  

Hey Dustin..Check your PM........!

Anyone interested in some API 500 format projects??

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