Sound Skulptor forums

Build help and troubleshooting => SK49 Multi-patern Tube Microphone => Topic started by: Alex Harmer on November 07, 2025, 07:15:38 AM

Title: How long is the 7-pin XLR cable that comes with the SK49 kit?
Post by: Alex Harmer on November 07, 2025, 07:15:38 AM
I am hoping to hang the SK49 microphones for orchestral recording from our local town hall. 

The ceiling is around 18 metres above the stage. 

Will the 7-pin XLR reach down from the power supply (in the ceiling), to rigging drop length, which is about 17 metres?

If not, do you recommend a good cable supplier?

Thanks :) 
Title: Re: How long is the 7-pin XLR cable that comes with the SK49 kit?
Post by: JPK on November 07, 2025, 09:30:39 AM
I am sorry, the cable is 6 meters long so you will need a longer cable.
https://www.designacable.com/7-pin-xlr-tube-microphone-cable-neutik-sommer-sc-octave-mic-lead.html

Title: Re: How long is the 7-pin XLR cable that comes with the SK49 kit?
Post by: Alex Harmer on November 08, 2025, 12:15:01 AM
Thank you, that’s fine.

My question now becomes… will I need to adjust the heater output voltage on a 25 metre cable run?

I think for 25 metres the voltage drop may be around 0.4v with 22AWG cable. Would it be safe for me to run it at 6.1v instead of the recommended 5.7v from your setup guide?
Title: Re: How long is the 7-pin XLR cable that comes with the SK49 kit?
Post by: JPK on November 08, 2025, 10:45:50 AM
I think the best method would be to check the voltage across R13 in the PSU.
You want around 140mA in the tube heater so the voltage should be about 0.14 * 27 = 3.78V.
If the current falls under 133mA (3.6V accross R13) you can lower the value of R13 to increase the current.
Title: Re: How long is the 7-pin XLR cable that comes with the SK49 kit?
Post by: Alex Harmer on November 08, 2025, 10:08:53 PM
Thank you. 

Last question:

The cable you linked above  (https://www.designacable.com/7-pin-xlr-tube-microphone-cable-neutik-sommer-sc-octave-mic-lead.html)has a lot of different variants, depending on the microphone. If you look at the drop-down menu, you will see. 

Which microphone cable is the SK49 compatible with, in terms of its XLR pinout?

Thanks,
Alex

Title: Re: How long is the 7-pin XLR cable that comes with the SK49 kit?
Post by: JPK on November 09, 2025, 04:14:07 PM
Probably Telefunken M16 Mk2 and t.bone.
But I would first check the compatibility with them:


If the cable has some thicker wires they should go to pins 7 (ground) first then to pin 2 (heater).
Title: Re: How long is the 7-pin XLR cable that comes with the SK49 kit?
Post by: Alex Harmer on November 09, 2025, 07:40:07 PM
Thank you! Very helpful.

Here is the Telefunken M16 Mark II pinout:


Title: Re: How long is the 7-pin XLR cable that comes with the SK49 kit?
Post by: JPK on November 10, 2025, 07:57:12 AM
Yes, this cable will work if the two ground wires are independent and not connected together in one of the XLR connectors.
Title: Re: How long is the 7-pin XLR cable that comes with the SK49 kit?
Post by: Alex Harmer on November 25, 2025, 10:57:37 PM
Thanks very much for an amazing microphone design!

I've just finished building my pair in New Zealand. They are working perfectly, no issues. 
Title: Re: How long is the 7-pin XLR cable that comes with the SK49 kit?
Post by: JPK on November 27, 2025, 11:34:32 AM
(https://fonts.gstatic.com/s/e/notoemoji/16.0/1f44d/32.png)
Title: Re: How long is the 7-pin XLR cable that comes with the SK49 kit?
Post by: Alex Harmer on April 21, 2026, 12:50:59 PM
Quote from: JPK on November 27, 2025, 11:34:32 AM
I think the best method would be to check the voltage across R13 in the PSU.
You want around 140mA in the tube heater so the voltage should be about 0.14 * 27 = 3.78V.
If the current falls under 133mA (3.6V accross R13) you can lower the value of R13 to increase the current.
Hi JPK,

I'm resurrecting this topic about the 25-metre long 7-pin cable for orchestral recording. 

Would you consider selling me two new power supplies with a specific value in R7 that would be appropriate for the voltage drop across this length of cable? 

The microphones are amazing - and rather than risk damaging the power supplies with some modifications that I don't understand, I'd prefer to have two dedicated power supplies for when I am using longer cables. 

What do you think? The microphones are amazing, and I'd like to use them for this task of longer cable runs. 

Cheers from New Zealand. 
Title: Re: How long is the 7-pin XLR cable that comes with the SK49 kit?
Post by: JPK on April 23, 2026, 11:55:51 AM
I just made the test with five 6m cables connected together for a total of 30m.
The voltage accross R13 was still adequate at 3.61V and this include 4 additionnal male/female XLR junction.
So I think you are OK with the standard PSU and a 25m cable as long as it is a 7 wires good quality cable.
Title: Re: How long is the 7-pin XLR cable that comes with the SK49 kit?
Post by: Alex Harmer on April 25, 2026, 08:59:29 PM
Quote from: JPK on April 23, 2026, 11:55:51 AM
I just made the test with five 6m cables connected together for a total of 30m.
The voltage accross R13 was still adequate at 3.61V and this include 4 additionnal male/female XLR junction.
So I think you are OK with the standard PSU and a 25m cable as long as it is a 7 wires good quality cable.
Thank you so much, that is incredibly helpful!