Line level splitter?

[JW]

I've been thinking about a box that splits the line level output of microphone preamps and/or other rack gear (compressors etc) on the way to the recorder (AD inputs) This would be a workaround in order to monitor with no latency with an external mixer, while I have the direct signal go straight to the converters.

Something like 8 in/16 out would be great. It's essential to keep the direct signal clean and un affected. Is the best way to do this to hang an opamp circuit in parallel off of the preamps outputs? (almost all of them are transformer outputs)

I'm not that concerned with perfect sound quality of the 'monitoring leg' as I am with maintaining the direct sound to the recorder.

???

 

[emrr]

Patchbay mults. I have a bay that's just used for this dedicated purpose, hits my monitor console and my AD in parallel.

 

[chilidawg]

Sorry to hijack an almost 2 year old thread. I don't want to start a new one, because I have a similar need as the original poster (or should I say, the client who is paying me to build the active 1:6 balanced line splitter unit)

Anyway, I'm thinking of 12 opamp buffers, arranged like in this schematic (shown for 2 channels)

Only problem is, I'm not sure if I have to add an output capacitor, or an output resistor, or both, for each opamp. Hoping that the resident experts can help clarify.

 

[Newmarket]

Sorry to hijack an almost 2 year old thread. I don't want to start a new one, because I have a similar need as the original poster (or should I say, the client who is paying me to build the active 1:6 balanced line splitter unit)

Anyway, I'm thinking of 12 opamp buffers, arranged like in this schematic (shown for 2 channels)

Only problem is, I'm not sure if I have to add an output capacitor, or an output resistor, or both, for each opamp. Hoping that the resident experts can help clarify.

Assuming your source is low impedance eg a preamp output, then you can likely just split the output without an additional opamp buffer. Unless driving a low impedance input like 600 Ohm.
With the circuit shown you would normally have a build out series resistor to avoid problems with cable capacitance. Capacitor optional but the safe bet as you don't generally know the details of the destination although most kit will ac couple at the input.
Apart from DC offset considerations a suitably rated capacitor helps with any P48 danger.

 

[chilidawg]

Totally understood that it's an overkill to have multiple opamp buffers, but it's what the guy wants.

I tested the circuit as it is, sounded pretty good, but my cable was very short. So just to play it safe, I will add a 100 ohm output resistor and 100uF/35V output cap, including another 47K resistor to ground after the cap.

Thanks for the clarification!

 

[jokeramik]

Use 50 Ohms and a 470µF output capacitor. It´s lowers the THD at the lower frequencies significantly.
Best regards!

 

[chilidawg]

Use 50 Ohms and a 470µF output capacitor. It´s lowers the THD at the lower frequencies significantly.
Best regards!

Unfortunately, I ran out of 470uF electrolytic caps. I used my last batch of Chemicon KZE in a few dozens of Meanwell SMPS repair for a local lighting company, and I'd rather not spend a dime to buy more but instead use/exhaust what I already have. Those components including tiny SMD parts are taking up too much space

 

[jokeramik]

Unfortunately, I ran out of 470uF electrolytic caps. I used my last batch of Chemicon KZE in a few dozens of Meanwell SMPS repair for a local lighting company, and I'd rather not spend a dime to buy more but instead use/exhaust what I already have. Those components including tiny SMD parts are taking up too much space

you decide what you do
best regards

 

[MidnightArrakis]

Unfortunately, I ran out of 470uF electrolytic caps. I used my last batch of Chemicon KZE in a few dozens of Meanwell SMPS repair for a local lighting company, and I'd rather not spend a dime to buy more but instead use/exhaust what I already have. Those components including tiny SMD parts are taking up too much space

[I'd rather not spend a dime to buy more but instead use/exhaust what I already have] -- You would be doing your client a great disservice by being so cheap as to not buy a few capacitors and do the job correctly, instead of merely using what happens to be laying around your workspace!!! In addition, as -- jokeramik -- had pointed out, his suggested capacitor and resistor values would offer greatly improved audio performance!!! >> DON'T BE A CHEESEBALL!!! << >> DO THE RIGHT THING!!! <<

NOTE: -- Use at least 63V electrolytic capacitors!!!

https://www.digikey.com/en/products/filter/aluminum-electrolytic-capacitors/58?s=N4IgjCBcoKwExVAYygMwIYBsDOBTANCAPZQDaIAzABxVwDsMIAuoQA4AuUIAyuwE4BLAHYBzEAF9CANgCciECkgYcBYmRAAWMGCoy6zNp0g9+wsZM0AGRtAVoseQiUjkKMSxqoUDIDl16CohKE7lTyisqOai7gFHRaIIRgdHTJPn7GAWbB4DK64fYqTuqWzBZwHnK2EQ6qzuQadJYABACtAGLpRiAAqkIC7ADyqACyuOjYAK58uDkVdFXIhVH1IFIUzQBqXVx9A8NjE9OzFgC0CNVQ-JN16oxMZ1IFkNe3Md6ECA8WNqCsUGA2P9IHAYOJxEA

And, just for grins and is distantly related to what it is that you are doing.....here is a rack-panel I had designed for a "12-Channel Microphone Splitter" system for a Canadian audio company:



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[Newmarket]

The build out series resistor value is not critical. 50 Ohm is not particularly convenient to obtain. More usually use 47R; 68R:100R as these are common Exx Series values. No need to be concerned with common RF characteristic impedances eg 50/75:Ohm.

 

[MidnightArrakis]

The build out series resistor value is not critical. 50 Ohm is not particularly convenient to obtain. More usually use 47R; 68R:100R as these are common Exx Series values. No need to be concerned with common RF characteristic impedances eg 50/75:Ohm.

[50 Ohm is not particularly convenient to obtain] -- Maybe not. But, -- 49.9-Ohm -- is close enough for Rock'N'Roll!!!

https://www.digikey.com/en/products/detail/yageo/MFR-25FTE52-49R9/9140237



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[chilidawg]

[I'd rather not spend a dime to buy more but instead use/exhaust what I already have] -- You would be doing your client a great disservice by being so cheap as to not buy a few capacitors and do the job correctly, instead of merely using what happens to be laying around your workspace!!! In addition, as -- jokeramik -- had pointed out, his suggested capacitor and resistor values would offer greatly improved audio performance!!! >> DON'T BE A CHEESEBALL!!! << >> DO THE RIGHT THING!!! <<

NOTE: -- Use at least 63V electrolytic capacitors!!!

https://www.digikey.com/en/products/filter/aluminum-electrolytic-capacitors/58?s=N4IgjCBcoKwExVAYygMwIYBsDOBTANCAPZQDaIAzABxVwDsMIAuoQA4AuUIAyuwE4BLAHYBzEAF9CANgCciECkgYcBYmRAAWMGCoy6zNp0g9+wsZM0AGRtAVoseQiUjkKMSxqoUDIDl16CohKE7lTyisqOai7gFHRaIIRgdHTJPn7GAWbB4DK64fYqTuqWzBZwHnK2EQ6qzuQadJYABACtAGLpRiAAqkIC7ADyqACyuOjYAK58uDkVdFXIhVH1IFIUzQBqXVx9A8NjE9OzFgC0CNVQ-JN16oxMZ1IFkNe3Md6ECA8WNqCsUGA2P9IHAYOJxEA

And, just for grins and is distantly related to what it is that you are doing.....here is a rack-panel I had designed for a "12-Channel Microphone Splitter" system for a Canadian audio company:

View attachment 137657

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YOU ARE VERY RUDE MY FRIEND, AND I DON'T AGREE WITH YOU!

I HAVE A LOT OF GOOD QUALITY COMPONENTS THAT I BOUGHT FROM MOUSER OVER THE YEARS, NOT FAKES FROM CHINA. I'M NOT CHEAPENING OUT ON ANYTHING OR DOING THE CUSTOMER A DISSERVICE.

I PRICED THIS 1:6 SPLITTER UNIT AT $20 WHICH IS WHAT HE COULD AFFORD TO PAY (NOT IN THE USA, OUR AVERAGE SALARY IS $300/MONTH) I BUILT IT BY HAND! IN 4 DAYS, SO YOU DO THE MATH IF I ACTUALLY MAKE A PROFIT OR NOT.