The Acoustic Guitar Forum

Go Back   The Acoustic Guitar Forum > General Acoustic Guitar and Amplification Discussion > Acoustic Amplification

Reply
 
Thread Tools
  #1  
Old 02-10-2021, 09:00 AM
Josh83 Josh83 is offline
Registered User
 
Join Date: Sep 2020
Posts: 5
Question Acoustic guitar with 2 pickups, but no internal mixer: what to do to make it mono?

Hey guys

I just wrote about a custom Taylor Dan Crary guitar which has two pickups installed. One goes to the left, one to the right stereo channel.

One pickup is for the strings, the other for the body sounds (ie. percussion).

The current owner used a Y-cable to split the stereo signal into a separate left and right mono output, then plugged each output into his mixer, and there he could decide how the signals would be mixed.

I'm a street busker traveling with minimal luggage, and I need to keep my gear as little as possible. I have two inputs on my little PA system, one for my microphone, the other one for my guitar. I don't want to carry around an additional mixer. So I need a way to mix those two signals together into a single mono channel.

I have no idea about acoustic engineering, but I think it should be possible somehow to build a simple adapter which has:

- at one end a male 1/4" TRS stereo signal (to receive the two pickups' individual signals)
- and then merges it into a 1/4" female TRS mono at the other end

Preferably, it would offer a little control dial/knob so I could manually choose the wanted ratio.

I have a friend who knows to solder audio cables and such, he just doesn't know a lot about guitar gear, so it would be great to get some advice from you guys.

Another way to go could be the installation of a small mixer into the guitar's body. I don't like the huge plastic elements and displays of many modern guitar mixers; in fact, the Taylor's unobtrusive three little knobs are most appealing to me (while the Dan Crary in question doesn't have any of these at all).



So maybe there is even a small mixer that allows for what I need which would only have a single knob on the outside of the guitar body (I don't care too much where it would be... possibly directly next to the stereo output)?

Any help is highly appreciated. Thanks a lot.
Josua

Last edited by Josh83; 02-10-2021 at 09:13 AM.
Reply With Quote
  #2  
Old 02-10-2021, 01:49 PM
James May's Avatar
James May James May is offline
AGF Sponsor
 
Join Date: Dec 2015
Location: Nevada City, CA
Posts: 711
Default

Assuming both pickups are active and have buffered outputs, you could simply use a 4.7K resistor from each to a common tie point as your mono output.

If you want adjust-ability, try a 10K pot and wire each end of the pot to each pickup, and the center wiper becomes your mono output.
__________________
James May
Audio Sprockets
maker of ToneDexter
James May Engineering
maker of the Ultra Tonic Pickup
Reply With Quote
  #3  
Old 02-11-2021, 01:50 PM
Josh83 Josh83 is offline
Registered User
 
Join Date: Sep 2020
Posts: 5
Default

Thanks for posting an idea.

My friend understands the first part, but is unsure about this:

> If you want adjust-ability, try a 10K pot and wire each end of the pot to each pickup, and the center wiper becomes your mono output.

Can you explain a bit more in detail, please?
Reply With Quote
  #4  
Old 02-11-2021, 02:13 PM
James May's Avatar
James May James May is offline
AGF Sponsor
 
Join Date: Dec 2015
Location: Nevada City, CA
Posts: 711
Default

Use a 10K linear pot.

Connect one of the outside terminals of the pot to the output from your first active pickup (on the TIP connection of the jack).

Connect the other outside terminal of the pot to the output from your second active pickup (on the RING connection of the jack).

The center connection of the pot then becomes your mono output which you can send to your amp. The pot will serve as a blend/balance control for the two pickups.
__________________
James May
Audio Sprockets
maker of ToneDexter
James May Engineering
maker of the Ultra Tonic Pickup
Reply With Quote
  #5  
Old 02-12-2021, 03:15 AM
Josh83 Josh83 is offline
Registered User
 
Join Date: Sep 2020
Posts: 5
Default

Thanks a lot for the more thorough explanations. :-)

Meanwhile, I have experimented with my friend a bit.

We first tried to follow these instructions here: https://qscprod.force.com/selfhelppo...-to-mono-input. But that didn't work out (sound was very, very low and bad quality). Not sure whether we did everything right?

After that, we have created a guitar cable with a male stereo jack on one side, then inside the cable, the left and right channels are combined (by simply soldering them together), and on the other side of the cable, there is a male mono jack.



As I don't have the Dan Crary guitar with me, we have simply tested it by connecting the stereo jack to a radio, and the mono jack to an active speaker. When panning to the very left or right on the radio side, either the left or the right stereo channel can be heard through the speaker. It seems to work pretty well (we couldn't distinguish sound quality by ear from a standard mono cable, although we couldn't turn up the volume too much because of sleeping kids). So the first goal (combining stereo into mono) seems to be achieved.

Question so far: is there any issue with our approach? I read somewhere about two channels "canceling themselves out" by just soldering them together.

If the two pickups of the Dan Crary guitar deliver roughly the same volume, then this would work pretty well. I'm unsure by the way whether the pickups are active or passive. The K&K Pure Mini seems to be passive (see https://www.kksound.com/products/puremini.php), while for the hexadecimal pickup I don't have any further information; I just wrote an email to the seller though.

After this first success, we wanted to experiment a little more. My idea was: if the two pickups do not deliver same volume, we only need to be able to lower the volume of the louder one so it matches the less loud one.

We took a 10k potentiometer, and created another cable that has a female mono jack on one side, a male mono jack on the other side, and a potentiometer between.



The proof of concept works: we can change the volume of the audio signal using the potentiometer's knob. (The change of volume is not really "linear" when rotating the knob, but it works just fine. Maybe a higher quality potentiometer would improve the experience even a bit.)

We could now combine the two ideas, so that the potentiometer would affect one channel (the left or the right one, depending which one is connected to the louder preamp) of the stereo jack. Afterwards, both channels could be soldered, and leave through the mono jack.

We are unsure though whether this will work with passive audio signals (we don't have any equipment here to test that). I will just have to test it with the Dan Crary guitar some day soon.

If it doesn't work: is there a potentiometer-like thing that works on passive audio sources? Or is there a resistor that I could just add to the louder channel (I suppose there exist resistors with different "strengths", so I would just need to find the one that fits best)?

THANKS A LOT FOR YOUR SUPPORT. :-)

Last edited by Josh83; 02-12-2021 at 03:29 AM.
Reply With Quote
  #6  
Old 02-28-2021, 10:54 AM
Todd123 Todd123 is offline
Registered User
 
Join Date: Jan 2007
Location: NJ
Posts: 27
Default

Geez that sounds like a lot of work.. get a blender preamp detar makes them several different companies make them I use a Felix but also have Detar.
Quote:
Originally Posted by Josh83 View Post
Thanks a lot for the more thorough explanations. :-)

Meanwhile, I have experimented with my friend a bit.

We first tried to follow these instructions here: https://qscprod.force.com/selfhelppo...-to-mono-input. But that didn't work out (sound was very, very low and bad quality). Not sure whether we did everything right?

After that, we have created a guitar cable with a male stereo jack on one side, then inside the cable, the left and right channels are combined (by simply soldering them together), and on the other side of the cable, there is a male mono jack.



As I don't have the Dan Crary guitar with me, we have simply tested it by connecting the stereo jack to a radio, and the mono jack to an active speaker. When panning to the very left or right on the radio side, either the left or the right stereo channel can be heard through the speaker. It seems to work pretty well (we couldn't distinguish sound quality by ear from a standard mono cable, although we couldn't turn up the volume too much because of sleeping kids). So the first goal (combining stereo into mono) seems to be achieved.

Question so far: is there any issue with our approach? I read somewhere about two channels "canceling themselves out" by just soldering them together.

If the two pickups of the Dan Crary guitar deliver roughly the same volume, then this would work pretty well. I'm unsure by the way whether the pickups are active or passive. The K&K Pure Mini seems to be passive (see https://www.kksound.com/products/puremini.php), while for the hexadecimal pickup I don't have any further information; I just wrote an email to the seller though.

After this first success, we wanted to experiment a little more. My idea was: if the two pickups do not deliver same volume, we only need to be able to lower the volume of the louder one so it matches the less loud one.

We took a 10k potentiometer, and created another cable that has a female mono jack on one side, a male mono jack on the other side, and a potentiometer between.



The proof of concept works: we can change the volume of the audio signal using the potentiometer's knob. (The change of volume is not really "linear" when rotating the knob, but it works just fine. Maybe a higher quality potentiometer would improve the experience even a bit.)

We could now combine the two ideas, so that the potentiometer would affect one channel (the left or the right one, depending which one is connected to the louder preamp) of the stereo jack. Afterwards, both channels could be soldered, and leave through the mono jack.

We are unsure though whether this will work with passive audio signals (we don't have any equipment here to test that). I will just have to test it with the Dan Crary guitar some day soon.

If it doesn't work: is there a potentiometer-like thing that works on passive audio sources? Or is there a resistor that I could just add to the louder channel (I suppose there exist resistors with different "strengths", so I would just need to find the one that fits best)?

THANKS A LOT FOR YOUR SUPPORT. :-)
Reply With Quote
  #7  
Old 02-28-2021, 11:26 AM
DungBeatle DungBeatle is offline
Registered User
 
Join Date: Jan 2016
Location: Idaho
Posts: 324
Default

Seems like this would fill your needs.

https://www.radialeng.com/product/mix-blender



~Bob
__________________
Some stuff...
Reply With Quote
  #8  
Old 02-28-2021, 02:48 PM
MrErikJ MrErikJ is offline
Registered User
 
Join Date: Apr 2016
Location: Kansas City
Posts: 1,142
Default

Get a 3’ TRS cable and a Baggs MixPro. It’ll sum both signals to mono and give you adjustable gain for both. You just wear it on your beltclip and it runs on 9volt.
__________________
Alvarez MC90
Guild GAD-50 w/Seymour Duncan Mag Mic
Taylor 352ce
Taylor 514ce

Zoom AC3

https://linktr.ee/erikjmusic

Last edited by MrErikJ; 02-28-2021 at 04:22 PM.
Reply With Quote
  #9  
Old 03-01-2021, 04:17 PM
euraquilo euraquilo is offline
Charter Member
 
Join Date: Aug 2017
Posts: 410
Default

Another option is the Schatten Mini-Pre 2 Dual Channel preamp.
__________________
Got some guitars, some keyboards, some melodicas, some skills and a little talent.
Reply With Quote
Reply

  The Acoustic Guitar Forum > General Acoustic Guitar and Amplification Discussion > Acoustic Amplification

Thread Tools





All times are GMT -6. The time now is 01:25 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright ©2000 - 2022, The Acoustic Guitar Forum
vB Ad Management by =RedTyger=