Hybrid 312 PCB

[bobschwenkler]

These boards are now available for folks who want to buy them.

www.bicyclerecordings.com/312



I've been working on a design for a 312 type preamp circuit board. I got most of the parts in and fired it up today. Works perfectly!

I built the board to accept standard 312 inputs, LL1538, and Jensen JT16A.

Outputs are servo or standard API transformer outs.

DC bias option for the +/- inputs.

Pad and polarity reversal on relay switches and +48V for phantom of course.

There'll be a Grayhill 12P on it when it's done.

I designed it to fit the Neutrik PCB mount XLR connectors and included mechanical brackets on the front and back; these boards will need no other mounting than to attach them to the front and back panels, similar to the 7th Circle models. Next project is to design the panel layout...

Tested with a JT16A, PTownkid 990 amp, and servo out. Compared to a Fabio 312 with CM-75101, 2520, and AP2623 out.

The API had a really cool character, but the detail and high end response in the 990 model was a big step up! Frequency response of the 990 model with my limited methods of testing seemed flat +.3dB from 10 to 20k, and noticeably more smooth than the 312's. At first I thought the frequency response must be exaggerated in the high end on the 990 model because I was hearing so much more there, but it seems to be a matter of detail rather than frequency response.

Below are a couple photos of the test jig.

In the end I'll be building an 8 channel unit. 2 ch. with JT16As and servos, 2 LL1528 and servos, 4 API style, all with 990 amps.

Once I have that all done and tested out, and assuming some marginal to moderate amount of interest, I'd love to sell some of these boards to people!

 

[vertiges]

:thumb: :thumb: :thumb:

Congratulations !!!

eD)))

 

[gevermil]

Id take two if you make some . Id like to make a 990 / jensen pre :sam:

 

[3nity]

:thumb:
look beautiful! very nice layout!

 

[RedNoise]

interested in a couple of these...depending on price.
Nice layout , I appreciate the switches in front!
will u sale only boards or full kits??both??

 

[bobschwenkler]

I'm not entirely sure about the per board cost. I'd like to keep it under $25 US, but it may be more.. If there seems to be enough interest I can get a larger quantity produced and be able to pass that saving on to the people who are buying.

I won't be doing full kits but will have full American BOMs for both servo and 312 style boards. I WILL be including the PCB mount connectors with the boards as they are pretty difficult to find (Neutrik right angle PCB mount XLR connectors models NC3MBHR and NC3FBHR-2. If anyone knows where to get them in small (<10) quantity please tell me where!).

It is conceivable that I could do full kits as requested, but that could be too much of a can of worms... We'll see.

-Edited for clarity

 

[RedNoise]

ok , I'm interested in PCB at the moment.

 

[RedNoise]

what about using cinemag trannies??cmoq2s & 75... ??do they feat your pcb?

 

[bobschwenkler]

The CMOQ2 outputs are the same size as the 2503. They'll fit.

What do you mean by 75...? If you mean the CM-75101APC then yes, it fits.

 

[RedNoise]

the cinemag input tran , I've lost the reference of my mind...
so 75+something(same than reliquia)

 

[bobschwenkler]

The CM-75101APC is probably the one you're thinking of.

 

[RedNoise]

yes it is!!

 

[RedNoise]

I'm at work , I will tell you the exact reference tonight

 

[vertiges]

[quote author="bobschwenkler"]I WILL be including the PCB mount connectors with the boards as they are pretty difficult to find (if anyone knows where to get them in small (<10) quantity please tell me where!).
[/quote]

I'm not sure I'm understand... Are you talking about the XLRs, the terminal blocks ?

Thanks,

eD

 

[bobschwenkler]

I guess I could be more specific... The Neutrik right angle PCB mount XLR connectors, models NC3FBHR-2 and NC3MBHR.

 

[Siegfried Meier]

These look alot like the SCA ones. How are they really different from those, or even 3nity's?

Sig

 

[codered]

I'm waiting for somebody to do the 312 in a 500 series format- I'm sure many others are too

 

[vertiges]

Hi,

Markertek has the NC3FBHR-1 (Pin 1 connected direct to chassis and shell ground)

http://www.markertek.com/SearchProd...ort=prod&skuonly=0&search=NC3FBHR&pagesize=20

But strange, they don't seem to have the male version.
Maybe it is possible to make a special order.

eD

 

[bobschwenkler]

[quote author="Siegfried Meier"]These look alot like the SCA ones. How are they really different from those, or even 3nity's?

Sig[/quote]

In regards to the 7th Circle, this PCB has more options sound-wise and circuit-wise whereas the their boards are one circuit per board. You can build up one of these boards for under half the cost of their kits. The circuit design differs. The board layout is different.

The most obvious similarities in my mind are the mounting style (though the method I'm using differs slightly from their method) and the Neutrik right angle PCB XLR jacks.

In regards to 3nity's, just glancing at his/her "for sale" thread it appears that this board design is a straight up 312 circuit. No servo, DC bias, mine has an additional input transformer mounting option, no relays, no board-mounted XLR jacks. The board layout is different. Someone please correct me if I'm wrong on anything in this paragraph (or others for that matter), I just looked at the photo of his or her PCB for about 30 sec to glean this info.

Maybe a good way to sum it up is that this board has more options and a very easy way to mount the board within a chassis with less wiring than when using panel mounted I/O.

 

[Miska]

I'm waiting for somebody to do the 312 in a 500 series format

...same here.