DB25 summing PCB - MK2??

[Bonsaimaster]

Front panel simple and elegant.

 

[ruffrecords]

Well done. I love the minimalist front panel. Can I use those two pics to send to Pierre to put in the gallery of projects using my designs?

Cheers

Ian

 

[Bonsaimaster]

Please

 

[Dr. Sampson]

HI Ian,
how are you? How are you fixed on these boards? I could use 5 of them, let me know 

thanx
T

Yes, I still have plenty in stock. Drop me an email with your order and delivery address and I will send you a Paypal  invoice.

Cheers

ian

Hi there,

I'd love 3 of these boards if you still have any?

Thanks very much! 

 

[ruffrecords]

Hi there,

I'd love 3 of these boards if you still have any?

Thanks very much! 

Yes, I still have some left. Just follow the instructions here to order:

http://groupdiy.com/index.php?topic=48986.msg619033#msg619033

Cheers

Ian

 

[barthman.de]

Hi Ian,

I'm thinking about to make a mono switch with "pan-law" - regulation. What do you think about the following schematic using relays (busses are connect to a Neumann V475_2 summing card):

 

[ruffrecords]

Hi Sebastian,

I think that will basically work OK and a channel switched to mono will be 3dB down on both buses which is fine for panning. Ther is only a could of point to watch. The load seen by the source changes when you switch to mono but most sources should not be bothered by that at all. The other thing is the bus impedance changes slightly when you switch because of the addition of the 2K4 reisstors but, with a total of 32 sources on the bus I do not think this will make any noticeable difference.

Cheers

Ian

 

[barthman.de]

Hi Sebastian,

I think that will basically work OK and a channel switched to mono will be 3dB down on both buses which is fine for panning. Ther is only a could of point to watch. The load seen by the source changes when you switch to mono but most sources should not be bothered by that at all. The other thing is the bus impedance changes slightly when you switch because of the addition of the 2K4 reisstors but, with a total of 32 sources on the bus I do not think this will make any noticeable difference.

Cheers

Ian

Thank you, I'll try it out.

I looked around here in the forum for other ideas to design my summing box. The following features would be fine:

- optional Passive Send (I have a lot of different preamps) and Return to the summing box
- separate Line Send and Return after summing stage to insert or bypass an analog signal path (for Master-Compressor and EQ...)
- output attenuator

I have no experience how send's and return's are designed. Can I do it simple like that? 
(for output attenuator I'd like to insert your "24 Step 1K Fader" before Peak/Correlation-Meter and Main Out)

 

 

[ruffrecords]

I looked around here in the forum for other ideas to design my summing box. The following features would be fine:

- optional Passive Send (I have a lot of different preamps) and Return to the summing box
- separate Line Send and Return after summing stage to insert or bypass an analog signal path (for Master-Compressor and EQ...)
- output attenuator

I have no experience how send's and return's are designed. Can I do it simple like that? 
(for output attenuator I'd like to insert your "24 Step 1K Fader" before Peak/Correlation-Meter and Main Out)

Your schematics look good to me. Switching in the bus resistor with a relay for passive mixing with an external amplifier should be fine. Your insert relay also looks good. I am not sure why everyone seems to use relays for this these days. In my day the insert was simply wired to a  normaled pair in a patch bay. If you wanted to insert something you just patched it in. I suppose the relay allows you to compare with and without the insert. Anyway, the choice is yours. Where to put the attenuator depends on what you want it to do. If it is just for final level tweaking then last thing in the chain would be best.

Cheers

Ian

 

[barthman.de]

I am not sure why everyone seems to use relays for this these days. In my day the insert was simply wired to a  normaled pair in a patch bay. If you wanted to insert something you just patched it in. I suppose the relay allows you to compare with and without the insert. Anyway, the choice is yours.

Cheers

Ian

Hi Ian,

thank you for your help. It will take some time to build this summing box but I will report (next year  ).

The idea is that all outputs of my DAW are wired with a patchbay and than with the summing box. So I can use plugins in the DAW or easy insert hardware on every channel before summing. For summing I can switch between very clean-sounding Neumann summing amp or preamps full of character. An yes, the relay on the Master is the easier way to A/B compare. Maybe I don't use it but 4 more relays are not a thing.

Maybe I'll get back to you to calculate the shunt resistors for passive summing network but I'll try to find it out alone at first.       

 

[mus1k_freak]

Could I run the output of the summing mixer into a pultec srpp type make up stage?

 

[ruffrecords]

Could I run the output of the summing mixer into a pultec srpp type make up stage?

You should be able to. The summing bus will need first to go through a 1:10 step up mic transformer which in turn can be connected directly to the grid of the SRPP stage. The two together should have enough make up gain.

Cheers

Ian

 

[barthman.de]

Maybe I'll get back to you to calculate the shunt resistors for passive summing network but I'll try to find it out alone at first.     

Let's try it:

32 channels / every channel: 2 x 5k11 = 10220
impedance: 200 ohm
shunt-resistor: 535,08 --> 536R

Right? 

All for stereo. If I switch 8 channels to mono the impedance is changing.

 

[ruffrecords]

Maybe I'll get back to you to calculate the shunt resistors for passive summing network but I'll try to find it out alone at first.     

Let's try it:

32 channels / every channel: 2 x 5k11 = 10220
impedance: 200 ohm
shunt-resistor: 535,08 --> 536R

Right? 

All for stereo. If I switch 8 channels to mono the impedance is changing.

Looks good to me. I make the bus impedance close to 320 ohms. I would use a 510 ohms bus resistor making the overall bus impedance 196 ohms. Close enough.

Cheers

Ian

 

[ruffrecords]

I am down to the last six DB25 boards. I am wondering whether to retire this now or whether to do another batch of say 50.
Any thoughts?

Cheers

Ian

 

[Holger]

Do another run Ian. It's a very useful PCB.

 

[anjing]

Hi Ian, I have been postponing but i sure would need one or two more,

Regards,

Pierre

 

[ruffrecords]

I decided to do one last run of 100. Boards just arrived.

Cheers

Ian

 

[currentstatus]

I decided to do one last run of 100. Boards just arrived.

Cheers

Ian

Hi Ian

Do you have any boards left please..

Thanks

 

[ruffrecords]

I decided to do one last run of 100. Boards just arrived.

Cheers

Ian

Hi Ian

Do you have any boards left please..

Thanks

Yes, I have plenty. You can always find the current stock levels by clicking on the Ruffrecords PCB Emporium tab on my web site:

http://www.customtubeconsoles.com/ruff-records-pcb-empporium

Cheers

Ian