DV Mark Little Jazz Aux Input

**rpjazzguitar** · 01-01-2019, 06:23 AM

Just tried the Aux Input in my new DV Mark.

I wanted to play IRealPro backing tracks from my phone through the amp.

But, instead of what I expected, I got an oscillating thumping hum when I plugged in the phone.

Then, I happened to try it again with the phone already in playback mode when I plugged it into the Aux In.

At that point, the noise stopped and the amp played the IRealPro track properly. Sounded fine.

BUT, as soon as the track finished playing, the noise came back. This time not oscillating. The Ground Lift button on the back didn't affect it.

The cable (stereo 1/8th inch) worked properly with my old setup, playing into a Zoom PX5D.

Would someone with a Little Jazz try this and report back?

Thanks in advance.

**tamirgal** · 01-01-2019, 06:37 AM

The aux input works as expected on mine. The audio quality on the aux in is not superb, but it functions ok. The only noise i get is when the aux cable is not connected to the phone. Otherwise it works fine. It might be a cable issue after all.
I actually would have preferred the master volume to control the aux as well, but it is what it is.

**rpjazzguitar** · 01-01-2019, 07:37 AM

Originally Posted by tamirgal

The aux input works as expected on mine. The audio quality on the aux in is not superb, but it functions ok. The only noise i get is when the aux cable is not connected to the phone. Otherwise it works fine. It might be a cable issue after all.
I actually would have preferred the master volume to control the aux as well, but it is what it is.

Thanks for checking it.

Stereo cable between phone and amp in your test?

BTW, I agree about the Master volume. Sure, you can control the volume with the phone, but why not the Master too?

**lawson-stone** · 01-01-2019, 10:45 AM

Mine works like the others here have noted. I notice, though, on the Micro50 head, that the aux input seems not to grip the plug very tightly. I have been tempted to open it up and just bend the contacts on the aux-in to grab the plug better, but I don't know what I'd be getting into doing that!

**Alder Statesman** · 01-01-2019, 11:18 AM

My Aux In works great on my LJ. The headphone jack hisses and is unusable, but I do not need that feature.

**sgosnell** · 01-01-2019, 11:23 AM

It may be an issue with your phone. Phones can sometimes be problematic with audio.

**DonEsteban** · 01-01-2019, 03:27 PM

Works fine here but I had the same thing happen when I tried to connect a small mixer to the aux in of the micro 50.

Pulsating hum noise, no way to stop it. When I connected an mp3 player using the same cable it played fine.

Most probably an impedance mismatch problem of some sorts...

**KirkP** · 01-01-2019, 04:00 PM

Using a mono cable would short out one channel of your phones output, which might create odd noises in the remaining channel.

**rpjazzguitar** · 01-01-2019, 05:44 PM

Originally Posted by DonEsteban

Works fine here but I had the same thing happen when I tried to connect a small mixer to the aux in of the micro 50.

Pulsating hum noise, no way to stop it. When I connected an mp3 player using the same cable it played fine.

Most probably an impedance mismatch problem of some sorts...

First off, thanks to everybody who replied. Much appreciated.

I emailed the company and I'll report back if they respond.

Since it works properly during playback, I'm thinking that the phone does something to the circuit when playback stops, but I don't understand what it might be. Maybe, for some reason, it completely opens the circuit. That is, instead of having some resistance between the hot and ground conductors of the cable, it creates infinite resistance and that produces hum. Doesn't explain the oscillation.

Anybody understand this stuff?

**DonEsteban** · 01-01-2019, 05:53 PM

Originally Posted by rpjazzguitar

Anybody understand this stuff?

Kiddin'? We're all guitarists! hahaha

No, seriously.. main problem as I see it, phone earphone plugs are 4 x connectors (stereo listen, left right and ground + microphone which shares the same ground). And of course - how could it be different - there is no standard.

So which ring is ground, mic and so on varies depending on make and system... a real bonanza of possible problems... and they want it like that, just to squeeze some extra bucks out of your pocket.

So, I'd first try to get a proper 4-connector to single connectors adapter, just to make sure everything is exactly connected to where it should. That'll be a starting point to troubleshooting.

**Jim Soloway** · 01-01-2019, 06:50 PM

The Aux input is the one great weakness on both the Little Jazz and the Jazz Micro 50 head. They're just really poorly implemented. We're actually using my Jazz 50 and my Buscarino cab as the main music system in our home right now until I can find something more suitable so I'm living with it every day. It sounds ok but I have to keep the gain on the amp around 1 and control the actual volume from the music player. I'll be happy when we get a real stereo.

**sgosnell** · 01-01-2019, 08:21 PM

What most people seem to be using now is bluetooth speakers. Wired connections are so 20th Century.

The Little Jazz probably has a standard 3-wire stereo jack, and the phone jack has the mic in addition to the stereo audio. That might be the issue. On my Android phone it works correctly, with no noise as long as the phone is connected. But I have no idea about iThings. DV Mark seems to have made a design decision to have the aux input not connected through the amp volume control. That makes sense in a way, because it allows the amp volume to be adjusted without affecting the aux input. I don't think there was any thought about using the amp as a stereo amplifier, just for guitar. There are tons of mini stereo amps available on ebay for $20-$30, and they're actually pretty good. I use one attached to my computer, splitting the audio from the HDMI into it, and from there to good passive stereo speakers, and get audio quality far better than any powered computer speakers I've found, and I have several sets sitting on shelves. I usually use that amp instead of going through the Little Jazz aux, because it sounds better, and I have control over the volume via a remote control.

**rpjazzguitar** · 01-01-2019, 09:18 PM

Originally Posted by sgosnell

What most people seem to be using now is bluetooth speakers. Wired connections are so 20th Century.

The Little Jazz probably has a standard 3-wire stereo jack, and the phone jack has the mic in addition to the stereo audio. That might be the issue. On my Android phone it works correctly, with no noise as long as the phone is connected. But I have no idea about iThings. DV Mark seems to have made a design decision to have the aux input not connected through the amp volume control. That makes sense in a way, because it allows the amp volume to be adjusted without affecting the aux input. I don't think there was any thought about using the amp as a stereo amplifier, just for guitar. There are tons of mini stereo amps available on ebay for $20-$30, and they're actually pretty good. I use one attached to my computer, splitting the audio from the HDMI into it, and from there to good passive stereo speakers, and get audio quality far better than any powered computer speakers I've found, and I have several sets sitting on shelves. I usually use that amp instead of going through the Little Jazz aux, because it sounds better, and I have control over the volume via a remote control.

I just tried going out of my laptop's 1/8 inch headphone output into the Little Jazz Aux In and it worked fine.

So, I'm guessing it has something to do with the microphone capability in my phone.

Oddly enough, that doesn't affect using my phone going into the Zoom PX5D. Maybe the difference is that the PX5D is stereo and the Little Jazz Aux In is mono, but that's a guess.

**sgosnell** · 01-01-2019, 09:25 PM

That could be. I've tried several times, using various apps, going with standard stereo cable from my phone to the LJ, and it all works fine. But I don't know how every manufacturer implements the audio output, and going from 4 conductors to just two could cause issues, depending on the implementation. I also don't have a schematic of the LJ, but I think it's almost certain that the stereo jack becomes mono there or immediately after it. You can't do stereo with one speaker.

**KirkP** · 01-02-2019, 02:42 PM

Originally Posted by sgosnell

I also don't have a schematic of the LJ, but I think it's almost certain that the stereo jack becomes mono there or immediately after it. You can't do stereo with one speaker.

Since the manual says the aux can accept input from a cell phone, it should be designed as a stereo input that then mixes the two channels down to one. The mixing circuit might be as simple as a couple of resistors. If the circuit doesn’t mix the channels they made a bonehead error.

I think use of a stereo cable instead of a 4-conductor cable does short out the microphone input to your phone, but phones are designed to work correctly with stereo cables. Otherwise you couldn’t listen with conventional headphones.

You might try a couple of different stereo cables. Sometimes the jacks on cheap cables have nonstandard plug shapes that don’t make good contact with some jacks. I’ve had that happen once or twice.

Also, (grasping for straws) if your phone is plugged into a power supply while it’s connected to your amp, that can form a ground loop and introduce noise.

Someone suggested you use a bluetooth speaker. You can buy a small bluetooth receiver for $15-25, and plug it into your aux input, to give it a bluetooth input. I use one in pre-bluetooth car and on my living room sound system. It should work fine in any aux input.

**lawson-stone** · 09-13-2019, 10:01 PM

Originally Posted by sgosnell

What most people seem to be using now is bluetooth speakers. Wired connections are so 20th Century.

The Little Jazz probably has a standard 3-wire stereo jack, and the phone jack has the mic in addition to the stereo audio. That might be the issue. On my Android phone it works correctly, with no noise as long as the phone is connected. But I have no idea about iThings. DV Mark seems to have made a design decision to have the aux input not connected through the amp volume control. That makes sense in a way, because it allows the amp volume to be adjusted without affecting the aux input. I don't think there was any thought about using the amp as a stereo amplifier, just for guitar. There are tons of mini stereo amps available on ebay for $20-$30, and they're actually pretty good. I use one attached to my computer, splitting the audio from the HDMI into it, and from there to good passive stereo speakers, and get audio quality far better than any powered computer speakers I've found, and I have several sets sitting on shelves. I usually use that amp instead of going through the Little Jazz aux, because it sounds better, and I have control over the volume via a remote control.

For me the point of the aux input isn't just to hear the backing track, it's also being able to record with it. Just hearing the track via bluetooth speakers doesn't get the signal into the mixer for recording.

**sgosnell** · 09-13-2019, 10:24 PM

There are other ways to get both signals to a recording device, of course, but mostly not as convenient.

**CHORC** · 11-06-2023, 03:44 PM

Sorry to be late to this particular party, but I have only just bought a DV Mark Jazz 12, and while I am happy with the amp, the aux input is, as others have noted, not very well implemented. When I plugged a small mixer into the aux socket (with its output volume turned fully down), I got a loud hum, which was also present, but to a lesser extent, when I plugged an iPad in directly. It sounded like an earth loop, although not sure how, since all the kit is plugged into the same extension board. However, I bought a small (cheap) earth loop breaker/isolator (PAC SNI-1 3.5) and put it between the mixer and the aux input, and it pretty much solved the problem - it’s not perfect, but at least it is now useable; just a pity it doesn’t have a volume control on as well. Oh well…..