Friday, October 10, 2025

Re: [Avid-L2] OTish: Audio Level Converter? Pyle Premium Direct Injection Audio Box - 2.36" x 4.09" Passive DI Unit Hum Eliminator w/ Input Attenuator to Connect Guitar & Bass, 1/4'' Impedance Transformer Connector to Balanced & Unbalanced XLR

Nerd alert

Not that it's relevant to your issue but it's worth noting that the XLR pinout 'standard' is anything but. Pin 2 + and Pin 3 - isn't universal, so grounding Pin 3 doesn't always work - sometimes you have to ground Pin 2. Even Shure couldn't make up their minds with an SM58 wired Pin 2 + and the inputs to their little mixer (I'm going back to the 80's here) having Pin 3 hot. 

I made a 4 channel DI box many years ago for a cabaret venue that had a both XLR and 1/4" inputs and outputs for each channel along with 4 audio isolation transformers and a bunch of switches to select which input socket, swap 2&3, short 2 or 3 to 1, ground input to output or keep them isolated. It wasn't for level matching, simply for hum removal. It got frequent use for a number of years. 

/nerd

Tony

Sent by magic over t'interweb


On 10 Oct 2025, at 09:35, John Moore via groups.io <bigfish=pacbell.net@groups.io> wrote:



[Edited Message Follows]

So I tested the Pyle Box which is a bass/guitar direct box and found it does work for my purposes.  I tried going straight out of the M-Track Duo main outs to the PA speaker amp consumer line input and it worked but there was a Hum.  The 1/4 inch to RCA cable was not a TRS 1/4 plug so plugging into the Balanced 1/4 main output on the M-Track shorted pin 1 shield to pin 3 low.  When I ran a TRS 1/4 to XLR cable from the M-Track Main Output to feed the Pyle XLR input/output connection and took Unbalanced instrument input connectors and connected them with the 1/4 unbalanced to RCA cables to feed PA speaker amp consumer line input it worked but depending on the position of the ground lift button the hum would come and go.  The ground lift button shorts pin 1 shield of the XLR connector of the Pyle box to chassis ground which ties it to the sleeve of the unbalance instrument connectors.
 
I found that I got a little more power out of the Headphone jack than the main outputs.  I did some googling around about +4dbu compared to the headphone output of 60mW/ch into 32 ohm and came up with the headphone works out to roughly +5.1 dbu which explains why it's a little louder than the main output.  So far it seems that going the extra mile for a isolation transformer is worth it to eliminate the hum.  I was surprised that I didn't need to use the attenuation switch on the pyle box.  I guess because I'm feeding from volume controlled outputs of the M-Track it wasn't overdriving the consumer line level inputs.
 
Here are the M-Track output specs for the nerds I try my best to emulate  ;-)
<mceclip0.png>
Posted by Video Geek Squad at 3:10 AM 0 comments

Re: [Avid-L2] OTish: Audio Level Converter? Pyle Premium Direct Injection Audio Box - 2.36" x 4.09" Passive DI Unit Hum Eliminator w/ Input Attenuator to Connect Guitar & Bass, 1/4'' Impedance Transformer Connector to Balanced & Unbalanced XLR

[Edited Message Follows]

So I tested the Pyle Box which is a bass/guitar direct box and found it does work for my purposes.  I tried going straight out of the M-Track Duo main outs to the PA speaker amp consumer line input and it worked but there was a Hum.  The 1/4 inch to RCA cable was not a TRS 1/4 plug so plugging into the Balanced 1/4 main output on the M-Track shorted pin 1 shield to pin 3 low.  When I ran a TRS 1/4 to XLR cable from the M-Track Main Output to feed the Pyle XLR input/output connection and took Unbalanced instrument input connectors and connected them with the 1/4 unbalanced to RCA cables to feed PA speaker amp consumer line input it worked but depending on the position of the ground lift button the hum would come and go.  The ground lift button shorts pin 1 shield of the XLR connector of the Pyle box to chassis ground which ties it to the sleeve of the unbalance instrument connectors.
 
I found that I got a little more power out of the Headphone jack than the main outputs.  I did some googling around about +4dbu compared to the headphone output of 60mW/ch into 32 ohm and came up with the headphone works out to roughly +5.1 dbu which explains why it's a little louder than the main output.  So far it seems that going the extra mile for a isolation transformer is worth it to eliminate the hum.  I was surprised that I didn't need to use the attenuation switch on the pyle box.  I guess because I'm feeding from volume controlled outputs of the M-Track it wasn't overdriving the consumer line level inputs.
 
Here are the M-Track output specs for the nerds I try my best to emulate  ;-)
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Posted by Video Geek Squad at 1:35 AM 0 comments

Re: [Avid-L2] OTish: Audio Level Converter? Pyle Premium Direct Injection Audio Box - 2.36" x 4.09" Passive DI Unit Hum Eliminator w/ Input Attenuator to Connect Guitar & Bass, 1/4'' Impedance Transformer Connector to Balanced & Unbalanced XLR

[Edited Message Follows]

So I tested the Pyle Box which is a bass/guitar direct box and found it does work for my purposes.  I tried going straight out of the M-Track Duo main outs to the PA speaker amp consumer line input and it worked but there was a Hum.  The 1/4 inch to RCA cable was not a TRS 1/4 plug so plugging into the Balanced 1/4 main output on the M-Track shorted pin 1 shield to pin 3 low.  When I ran a TRS 1/4 to XLR cable from the M-Track Main Output to feed the Pyle XLR input/output connection and took Unbalanced instrument input connectors and connected them with the 1/4 unbalanced to RCA cables to feed PA speaker amp consumer line input it worked but depending on the position of the ground lift button the hum would come and go.  The ground lift button shorts pin 1 shield of the XLR connector of the Pyle box to chassis ground.
 
I found that I got a little more power out of the Headphone jack than the main outputs.  I did some googling around about +4dbu compared to the headphone output of 60mW/ch into 32 ohm and came up with the headphone works out to roughly +5.1 dbu which explains why it's a little louder than the main output.  So far it seems that going the extra mile for a isolation transformer is worth it to eliminate the hum.  I was surprised that I didn't need to use the attenuation switch on the pyle box.  I guess because I'm feeding from volume controlled outputs of the M-Track it wasn't overdriving the consumer line level inputs.
 
Here are the M-Track output specs for the nerds I try my best to emulate  ;-)
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Posted by Video Geek Squad at 1:32 AM 0 comments

Re: [Avid-L2] OTish: Audio Level Converter? Pyle Premium Direct Injection Audio Box - 2.36" x 4.09" Passive DI Unit Hum Eliminator w/ Input Attenuator to Connect Guitar & Bass, 1/4'' Impedance Transformer Connector to Balanced & Unbalanced XLR

So I tested the Pyle Box which is a bass/guitar direct box and found it does work for my purposes.  I tried going straight out of the M-Track Duo main outs to the PA speaker amp consumer line input and it worked but there was a Hum.  The 1/4 inch to RCA cable was not a TRS 1/4 plug so plugging into the Balanced 1/4 main output on the M-Track shorted pin 1 shield to pin 3 low on the XLR input going to the Pyle box.  When I ran a TRS 1/4 to XLR cable from the M-Track Main Output to feed the Pyle XLR input/output connection and took Unbalanced instrument input connectors and connected them with the 1/4 unbalanced to RCA cables to feed PA speaker amp consumer line input it worked but depending on the position of the ground lift button the hum would come and go.  The ground lift button shorts pin 1 shield of the XLR connector of the Pyle box to chassis ground.
 
I found that I got a little more power out of the Headphone jack than the main outputs.  I did some googling around about +4dbu compared to the headphone output of 60mW/ch into 32 ohm and came up with the headphone works out to roughly +5.1 dbu which explains why it's a little louder than the main output.  So far it seems that going the extra mile for a isolation transformer is worth it to eliminate the hum.  I was surprised that I didn't need to use the attenuation switch on the pyle box.  I guess because I'm feeding from volume controlled outputs of the M-Track it wasn't overdriving the consumer line level inputs.
 
Here are the M-Track output specs for the nerds I try my best to emulate  ;-)
Posted by Video Geek Squad at 1:27 AM 0 comments

Wednesday, October 8, 2025

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Monday, October 6, 2025

Re: [Avid-L2] OTish: Audio Level Converter? Pyle Premium Direct Injection Audio Box - 2.36" x 4.09" Passive DI Unit Hum Eliminator w/ Input Attenuator to Connect Guitar & Bass, 1/4'' Impedance Transformer Connector to Balanced & Unbalanced XLR

I designed a cable for this in my early years at Avid.  It was for connecting the AudioMedia III card (-10dBV) for Media Composer to a Sony VTR (+4dBu). I'd look up the part number but that was over 20 years ago, so doubt you could find one.  Note if you roll your own there is only a 12.8dB difference, and this goes down to 6.4 if you take the output single-ended from the M-Audio. You really could do this by just turning down the input gain. and not using pin 3 of the XLR.  Just take pin 2 (center pin) and pin 1 (shield/sleeve of the RCA) from the XLR into your speaker.
 
But, if you want a professional solution, what I recommend today is this inexpensive (well under $100) unit from ART:  

       "ART CLEANBoxPro Bi-Directional Level Matching Converter"

You can get them from any major retailer like B&H, Sweetwater, or Full Compass.
 
The aforementioned wire is the only hardware design I ever used my electrical engineering degree for professionally.  Everything else was software :-)
   - Jeff
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Posted by Video Geek Squad at 6:45 AM 0 comments

Sunday, October 5, 2025

Re: [Avid-L2] OTish: Audio Level Converter? Pyle Premium Direct Injection Audio Box - 2.36" x 4.09" Passive DI Unit Hum Eliminator w/ Input Attenuator to Connect Guitar & Bass, 1/4'' Impedance Transformer Connector to Balanced & Unbalanced XLR

I use and love a Henry Matchbox for this kind of application. I am aware that the goal here is cheap and available, sometimes a Henry isn't either. But right now there are a bunch on eBay around $30. These are so nice, I wish they were that price when I bought mine.




On Sun, Oct 5, 2025 at 3:21 PM John Moore via groups.io <bigfish=pacbell.net@groups.io> wrote:
All good suggestions.  I thought just turning down the volume on the main or headphone output might do it but wanted to be prepared if it didn't.

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Posted by Video Geek Squad at 10:53 PM 0 comments

Re: [Avid-L2] OTish: Audio Level Converter? Pyle Premium Direct Injection Audio Box - 2.36" x 4.09" Passive DI Unit Hum Eliminator w/ Input Attenuator to Connect Guitar & Bass, 1/4'' Impedance Transformer Connector to Balanced & Unbalanced XLR

All good suggestions.  I thought just turning down the volume on the main or headphone output might do it but wanted to be prepared if it didn't.
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Posted by Video Geek Squad at 12:21 PM 0 comments

Re: [Avid-L2] OTish: Audio Level Converter? Pyle Premium Direct Injection Audio Box - 2.36" x 4.09" Passive DI Unit Hum Eliminator w/ Input Attenuator to Connect Guitar & Bass, 1/4'' Impedance Transformer Connector to Balanced & Unbalanced XLR

A 14dB drop is about 80% reduction. So a series 100 ohm resistor and a 20 ohm across the output would work if it's all unbalanced. A simple T attenuator. Cost - around a dollar. 

Tony

Sent by magic over t'interweb


On 5 Oct 2025, at 07:58, bouke via groups.io <bouke=editb.nl@groups.io> wrote:

A single resistor soldered in a plug will to the trick. 
Custom cable for a few dollar of parts.

(Forgot the value, but ai will tell)

Bouke

On 5 Oct 2025, at 07:42, John Moore via groups.io <bigfish=pacbell.net@groups.io> wrote:

I'm thinking of trying to use this box to take the +4db main output of an M-Audio M-Track Duo to -10db consumer level to feed a powered PA Speaker/Amp unit that has consumer level RCA inputs.  There are more active units but they cost more.  This is a one off Zoom Comedy show for a non profit meeting hall I attend so I'm not trying to get super picky.  The fact that it seems bi-directional and has a attenuator I'd think the -20db setting would take the +4 signal down to the consumer level -10db ballpark.  

Pyle Premium Direct Injection Audio Box - 2.36" x 4.09" Passive DI Unit Hum Eliminator w/ Input Attenuator to Connect Guitar & Bass, 1/4'' Impedance Transformer Connector to Balanced & Unbalanced XLR



John Moore Barking Trout Productions Studio City, CA bigfish@pacbell.net

Posted by Video Geek Squad at 7:36 AM 0 comments

Re: [Avid-L2] OTish: Audio Level Converter? Pyle Premium Direct Injection Audio Box - 2.36" x 4.09" Passive DI Unit Hum Eliminator w/ Input Attenuator to Connect Guitar & Bass, 1/4'' Impedance Transformer Connector to Balanced & Unbalanced XLR

I'm not familiar with that Pyle unit but, by way of a gross generalization, matching transformers shine when you need to go from unbalanced to balanced and when you're dealing with circuits that are super finicky about impedance. The downside is that there's usually a strong correlation between price and distortion.  Your solution might be as simple as turning the output level down on the MAudio box and turning the input level down on your powered speaker. If that doesn't work, you could probably use an inexpensive L-pad plugged in just before the signal hits the PA. If Radio Shack still existed you could buy a dollar's worth of resistors locally and roll your own. JB

On Oct 5, 2025, at 12:42 AM, John Moore via groups.io <bigfish=pacbell.net@groups.io> wrote:


I'm thinking of trying to use this box to take the +4db main output of an M-Audio M-Track Duo to -10db consumer level to feed a powered PA Speaker/Amp unit that has consumer level RCA inputs.  There are more active units but they cost more.  This is a one off Zoom Comedy show for a non profit meeting hall I attend so I'm not trying to get super picky.  The fact that it seems bi-directional and has a attenuator I'd think the -20db setting would take the +4 signal down to the consumer level -10db ballpark.  

Pyle Premium Direct Injection Audio Box - 2.36" x 4.09" Passive DI Unit Hum Eliminator w/ Input Attenuator to Connect Guitar & Bass, 1/4'' Impedance Transformer Connector to Balanced & Unbalanced XLR



John Moore Barking Trout Productions Studio City, CA bigfish@pacbell.net
Posted by Video Geek Squad at 7:06 AM 0 comments

Re: [Avid-L2] OTish: Audio Level Converter? Pyle Premium Direct Injection Audio Box - 2.36" x 4.09" Passive DI Unit Hum Eliminator w/ Input Attenuator to Connect Guitar & Bass, 1/4'' Impedance Transformer Connector to Balanced & Unbalanced XLR

Without knowledge of the cabling distances involved in your setup... why don't you use the headphone output of the M-Audio box?
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Posted by Video Geek Squad at 4:24 AM 0 comments
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