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Unofficial Mackie User Forums => DL1608/DL806/DL32R/ProDX Mixers => Topic started by: Greg C. on August 19, 2014, 11:39:05 PM

Title: Combing channels from a 3.5mm stereo jack to mono
Post by: Greg C. on August 19, 2014, 11:39:05 PM
Several of you have mentioned that you don't want to use up 2 channels of your mixer (understandable) for music playback from your iPod/iPad/MP3 player/laptop/etc. So far, I haven't found a cable pre made on the market that does proper resistive summing of the left and right channels. There are plenty that don't like this common Hosa cable (http://www.amazon.com/Hosa-Cable-CMP105-Inch-TRS/dp/B000068O3F). They merely short the left and right hots together. Though you're device may have some protection from burning out the output driver of your headphone jack, it's not ideal. At minimum it can result in distortion, at worst it can result in damage to the output. I'm sure many of you have read "Why Not Wye" (http://www.rane.com/note109.html), that pretty much explains it all. If you don't feel like building such a cable, you might consider something like the IsoPod (http://whirlwindusa.com/catalog/black-boxes-effects-and-dis/transformers-isolation-devices/isopod). There are also DIs on the market that will properly sum line output to mono made by Whirlwind, Radial, etc. FWIW.
Title: Re: Combing channels from a 3.5mm stereo jack to mono
Post by: RoadRanger on August 19, 2014, 11:57:23 PM
http://www.pimfg.com/Product-Detail/PVS-582-PT
Works great! :)
Title: Re: Combing channels from a 3.5mm stereo jack to mono
Post by: WK154 on August 20, 2014, 01:58:32 AM
So what's wrong with a $4.55 cable that gives you the option to go one or two DL channels with an iPad by flipping a switch (software) for mono or stereo? If your devise doesn't have this ability (stereo to mono) I can see the benefit of other solutions.
http://www.bhphotovideo.com/c/product/846982-REG/Hosa_Technology_HMP_003Y_REAN_3_5_mm_TRS.html
Title: Re: Combing channels from a 3.5mm stereo jack to mono
Post by: RoadRanger on August 20, 2014, 02:37:35 AM
It's pretty common for a band to have stuff they want to play (break music and/or tracks) on an iPhone, MP3 player, or whatever and I don't want to have to go into it to set it to mono. BTW that transformer thing I linked has a REALLY short cord but you can just use a regular XLR cord to extend it out to wherever it need to be - I generally prefer whomever owns it to operate it instead of me fumbling with it. That way it's not my fault if it's messed up ;) .
Title: Re: Combing channels from a 3.5mm stereo jack to mono
Post by: Greg C. on August 20, 2014, 05:46:59 AM
http://www.pimfg.com/Product-Detail/PVS-582-PT
Works great! :)

There we go, I knew I has seen a couple of different solutions out there. Just couldn't track them down. This isn't unlike the Whirlwind device, a lot less expensive though. I wonder how good the transformer is as far as LF saturation goes...
Title: Re: Combing channels from a 3.5mm stereo jack to mono
Post by: Keyboard Magic on August 20, 2014, 01:38:14 PM
I don't know if you can get ART Pro Audio Gear everywhere, but here's another option to check out if anyone's interested? The price is Canadian, and maybe a little expensive? It might be worth a look just the same.

http://www.long-mcquade.com/11048/Pro_Audio_Recording/Mic_Preamps_DI_Boxes/ART_Pro_Audio/ART_Stereo_Multi-Media_Interface_to_Single_Mic_Input.htm

 ;)
Title: Re: Combing channels from a 3.5mm stereo jack to mono
Post by: stevegarris on August 20, 2014, 10:20:55 PM
Wow - a lot of great choices here - Thanks Greg!

The Whirlwind unit looks nice, but $50 is a lot after seeing the $12 cable from PI.

I had looked and and considered the ART unit at one time.

I'm going to order the PI unit today.
Title: Re: Combing channels from a 3.5mm stereo jack to mono
Post by: Greg C. on August 20, 2014, 10:26:33 PM
I suspect the Whirlwind model has a better transformer which means flatter frequency response and less distortion - especially with hotter input levels. Typically the cheapy transformers, like in cheap DIs and line level isolation transformers, tend to saturate at lower frequencies and add distortion. But the PI probably works fine based on Road Ranger's observation.
Title: Re: Combing channels from a 3.5mm stereo jack to mono
Post by: stevegarris on August 21, 2014, 06:33:03 PM
I suspect the Whirlwind model has a better transformer which means flatter frequency response and less distortion - especially with hotter input levels. Typically the cheapy transformers, like in cheap DIs and line level isolation transformers, tend to saturate at lower frequencies and add distortion. But the PI probably works fine based on Road Ranger's observation.

I'll let you know, I've got one coming.
Title: Re: Combing channels from a 3.5mm stereo jack to mono
Post by: stevegarris on August 27, 2014, 06:58:18 PM
I suspect the Whirlwind model has a better transformer which means flatter frequency response and less distortion - especially with hotter input levels. Typically the cheapy transformers, like in cheap DIs and line level isolation transformers, tend to saturate at lower frequencies and add distortion. But the PI probably works fine based on Road Ranger's observation.

I'll let you know, I've got one coming.

OK - Last night I did a quick test. I found the Beatles recording that always sounded funny on playback (disappearing guitars, weird instrument levels changes). Tried both my Radio Shack stereo to mono adapter, and the PI transformer cable.

Neither cable fixed the weird sound on this recording, which I believe is a bad mp3 file. The Radio Shack cable sounded best, with excellent bass and clarity. The PI cable really sounded bad in comparison. I left my Radio Shack cable in the rest of the night, playing recorded music for a small dinner party we were having. Everything coming through it sounded fantastic.

I'm going to do some additional testing, but my preliminary report is that the PI "DJ" transformer cable is no better than a simple adapter, and perhaps worse.
Title: Re: Combing channels from a 3.5mm stereo jack to mono
Post by: Greg C. on August 27, 2014, 07:13:52 PM
OK - Last night I did a quick test. I found the Beatles recording that always sounded funny on playback (disappearing guitars, weird instrument levels changes). Tried both my Radio Shack stereo to mono adapter, and the PI transformer cable.

Neither cable fixed the weird sound on this recording, which I believe is a bad mp3 file. The Radio Shack cable sounded best, with excellent bass and clarity. The PI cable really sounded bad in comparison. I left my Radio Shack cable in the rest of the night, playing recorded music for a small dinner party we were having. Everything coming through it sounded fantastic.

I'm going to do some additional testing, but my preliminary report is that the PI "DJ" transformer cable is no better than a simple adapter, and perhaps worse.


It sounds like the file might be shifting stuff in and out of phase left relative to right. When in full stereo, you wouldn't notice it so much in the acoustic domain. But when summed electrically, it cancels before it makes it out to the speakers.
Title: Re: Combing channels from a 3.5mm stereo jack to mono
Post by: cupojoe on August 28, 2014, 06:15:54 PM
new dl1608 user - forum lurker until now

We use an iphone into the dl1608 for music to start sound checking and for breaks.   I also went the DI box route to get it to one channel :

 http://www.musiciansfriend.com/pro-audio/rapco-horizon-stl-1-stereo-line-direct-box?source=3WWRWXGP&gclid=Cj0KEQjwpvufBRCwzp_zyqfkhrcBEiQA8b-SHFJ1nXlwrbtEWmZsiCHUlEzQlWoHBgbni88BitGtjZ8aAvDQ8P8HAQ&kwid=productads-plaid^82226234787-sku^336017000000000@ADL4MF-adType^PLA-device^c-adid^51870555867 (http://www.musiciansfriend.com/pro-audio/rapco-horizon-stl-1-stereo-line-direct-box?source=3WWRWXGP&gclid=Cj0KEQjwpvufBRCwzp_zyqfkhrcBEiQA8b-SHFJ1nXlwrbtEWmZsiCHUlEzQlWoHBgbni88BitGtjZ8aAvDQ8P8HAQ&kwid=productads-plaid^82226234787-sku^336017000000000@ADL4MF-adType^PLA-device^c-adid^51870555867)

It works great with left and right inputs down to one XLR out (XLR B channel in mono mode).    I also use phantom power so I wanted that separation.  However, I'd totally opt for a simpler cable solution if anyone has a less cumbersome suggestion than a DI box.   
Title: Re: Combing channels from a 3.5mm stereo jack to mono
Post by: thedrums on August 28, 2014, 08:29:17 PM
Quote
However, I'd totally opt for a simpler cable solution if anyone has a less cumbersome suggestion than a DI box.   


http://www.sweetwater.com/store/detail/ISOPOD (http://www.sweetwater.com/store/detail/ISOPOD)
Title: Re: Combing channels from a 3.5mm stereo jack to mono
Post by: gtrdudes on August 29, 2014, 06:14:44 AM
For what it's worth I've made the hosa type cable. Left and right (tip and ring of the 1/8") to the hot (tip of the 1/4"). Used it for two years now with no problems.  I've used iPhones, iPods, etc... 

If it works, Wye fix it.
Title: Re: Combing channels from a 3.5mm stereo jack to mono
Post by: cupojoe on August 29, 2014, 02:15:11 PM
Quote
However, I'd totally opt for a simpler cable solution if anyone has a less cumbersome suggestion than a DI box.   


http://www.sweetwater.com/store/detail/ISOPOD (http://www.sweetwater.com/store/detail/ISOPOD)

Thanks.   I hadn't seen that before... Slick.
Title: Re: Combing channels from a 3.5mm stereo jack to mono
Post by: Greg C. on August 29, 2014, 02:24:39 PM
I linked to it in my original post.
Title: Re: Combing channels from a 3.5mm stereo jack to mono
Post by: Wynnd on August 29, 2014, 02:26:05 PM
I found a mini-phone plug to two XLR cable at Guitar Center.  Works fine with airplay or devices.  Probably need to watch out for phantom power, but I don't use that very often.  (Actually one of the things I don't like about the mixer.  Think phantom power should be restricted to the first bank, channels 1-8.  Wonder if there's an easy way to change that after my warranty ends.) 
Title: Re: Combing channels from a 3.5mm stereo jack to mono
Post by: stevegarris on August 31, 2014, 01:51:20 AM
I suspect the Whirlwind model has a better transformer which means flatter frequency response and less distortion - especially with hotter input levels. Typically the cheapy transformers, like in cheap DIs and line level isolation transformers, tend to saturate at lower frequencies and add distortion. But the PI probably works fine based on Road Ranger's observation.

I'll let you know, I've got one coming.

Another test today:

I compared the PI transformer cable against my Radio Shack stereo to 1/4" mono cable using various recordings on the iPod.  The results; They both sounded exactly the same. Full fidelity, no distortion, same input level, same output volume.
Title: Re: Combing channels from a 3.5mm stereo jack to mono
Post by: robbocurry on September 01, 2014, 08:49:14 AM
Quote
However, I'd totally opt for a simpler cable solution if anyone has a less cumbersome suggestion than a DI box.   


http://www.sweetwater.com/store/detail/ISOPOD (http://www.sweetwater.com/store/detail/ISOPOD)

Thanks.   I hadn't seen that before... Slick.

Looks great, bit expensive though compared to a DI box.
Title: Re: Combing channels from a 3.5mm stereo jack to mono
Post by: gtrdudes on September 01, 2014, 01:12:45 PM
This one is $10 cheaper and has a volume control. Works great.

http://www.sweetwater.com/store/detail/LTIBLOX
Title: Re: Combing channels from a 3.5mm stereo jack to mono
Post by: WK154 on September 01, 2014, 04:55:42 PM
According to the specs this is a mono (single) channel 3.5mm to TRS converter and states nothing about combining two channels (stereo). I find a lot of recordings to be dual mono anyway (mono compatibility) which makes all this converting meaningless and for the few that are true stereo combining the two channels before speaker output looses the whole effect anyways. It does however combine all sounds, a simple setting in the iPad.  In your typical gig (a mono environment) it's pointless unless you have true stereo music for playback. It only makes sense in a home theater environment and in a specific designated location (sweet spot). L is the conventional input for a stereo setup if you have a mono source for equipment that has the facility. The DL only requires one input channel and directs sound according to your output setup.