Need more inputs

[Silver Strings]

I need to add more channels to my DP-32SD. I’ve used up all the inputs and I need to add a couple of more mics and instruments. Can I do so and if so, how do I go about doing this. I’m not looking to spend a lot of $$$ on this so any suggestions on what good quality budget mixer (or whatever you would call this gadget) that I should get would be appreciated.

 

[Matt B]

Are you recording a huge ensemble?

I have most of the inputs of my DP24 filled up, but that is mainly because I don't like moving the cables around. It is acceptable to use a single input, reassign it to the desired channel, and record all of the tracks for a song. You would only need multiple inputs of you are recording several different instruments (or different mics on the same instrument), at one time.

If you are recording a lot of stuff at one time, there are a lot of good mixers out there you could use. I am sure one of us (more recent experience than me) can help find a good one for you.

Matt B

 

[David Porter]

Unless I'm misunderstanding... it seems to me that a small Mackie mixer like the $75.00 Mix 8 or something similar will do the trick. Just sub-mix to a stereo pair.

 

[Silver Strings]

Matt, I’m not recording yet. The mission at this point is using it as a basic mixer. I have a little wannabe band that practices in my studio with keyboard, bass, two guitars, mandolin and 3 mics. An electric drum kit and a fiddle will be joining us soon and I want more mic inputs for back up vocals. At times when we get all bowed up and chest beating because we think we nailed a song we then like to record it as an ensemble.

 

[Matt B]

Got it. A good basic mixer would do the job. With enough channels, you could sub-mix the drums, the vocals or both!

Just be aware that the channel count and full channel count on mixers can be very different numbers - a 12-channle board might have only 4 fully-controllable channels.

Let us know what you get.

Matt B

 

[Silver Strings]

Hey Matt, I ended up getting a Mackie ProFX16v2. Very nice board. I have the two hooked up .... main out of sub mixer (Mackie) via 1/4” TRS to main mixer (Tascam) channel 1 & 2 via XLR. I stumbled across a video that said whenever possible use line level jacks to tie the two together. I was under the impression that from a signal conduit standpoint XLR & 1/4” TRS were basically the same? The two mixers are right next to each other so distance is not a factor. The video was hooking up with regular guitar cables which I assume were TS cables. Does it matter if I connect the two with 1/4” TRS x XLR or 1/4” TRS x 1/4” TRS or XLR x XLR? Any advantage of one way over the other?

I’m all ears

 

[Matt B]

A bit above my "pay grade," but you hadn't gotten an answer yet. This is what I THINK is right.

On XLR vs TRS, they may be different. A TRS can be a stereo signal. If not stereo, it will make little difference on short runs. The XLR is a balanced line, more resistant to interference and signal loss due to long cable runs. Going from XLR output to a 1/4 input (with appropriate cable) will work, but will subject the setup to the same interference and distance loss as a 1/4 to 1/4. I think your set-up as described is fine. If you need 50 feet between the Mackie and the DP, reconsider then.

Line level is a stronger signal than mic level, having been amplified. It will be much more resistant to interference and signal loss. A line level output must be matched to a line level input, or you may get overload distortion.

Someone else please let us know if I got it all correct.

That looks like a fine mixer. I am amazed how good and reasonably-priced stuff is now. Back in the 70s, a setup with the capabilities of a DP24, non digital would have probably cost $30K. Our prize mixer was a Tapco, noisy and temperamental, and was probably way over $1000.

 

[Mark Richards]

This may shed some light on using the XLR inputs v the 1/4" phone inputs.
http://www.tascamforums.com/threads/dp-24-32sd-tutorial-videos.4475/page-4#post-25973

If your mixer output is line level (e.g. meant to be connected to an amplifier or other high impedance input device) you should be using Hi to Low impedance step down transformers to run the mixer into the DP XLR mic input (which is mic level/low impedance). The transformer would be 1/4" plug on one end; male XLR on the other end. The transformer connects to the DP using a standard XLR M/F mic cable or XLR M/F short patch cable. These should be available on Amazon and most pro music stores.

TRS cables have two hot wires and a ground shield inside. The same signal is carried through both hot wires. One signal is made out of phase with the other electronically by the receiving device's input circuitry and only one of the hot wires carries the signal into the receiving input circuitry. Any noise that built up in the signal is canceled out. This is an oversimplification, but the idea is to compensate for signal loss in long cable runs by eliminating noise buildup so a clean signal can be raised up to a usable level at the end of the long cable run. XLR cables/inputs work the same way

The DP 1/4" input is TRS line level/high impedance (22kOhm). If the cable run is under 6 feet I would just use unbalanced cable with TS 1/4" phono plugs on each end.

You also need to pay attention to the source impedance (the mixer output) and the load impedance ( the DP input). The latter should be at least 5x the former, and preferably 10x or better.

 

[Silver Strings]

Gentlemen, thank you very much for your input. All that technical stuff is leading me down a road I’ve never been on before so I’m doing a study on it so I have a better understanding about what it all means. I just didn’t realize all that needed to be considered. The width of my thinking was just connect balanced cables to it (balanced to keep the signal clean) and adjust the input channel trims so that each mixer was as close to unity gain as possible and I would be good to go. I did that using a tone generator and both mixers meeters seemed in sync, not perfect but very close without clipping. Then when I saw the video I mentioned on the previous post, I realized that I might be missing something here and figured I should reach out for help. In the mean time I experimented using different cable configurations and saw a significant difference in the signal output (clipping or -30’ish dBu) depending on the cable configuration I was testing. Now I’m getting an education on the missing piece of the puzzle. Thanks again for pointing me in the right direction. I probably will be asking more questions as I begin to get my head wrapped around this piece.

Mark, when you say I should be using a high to low impedance step down transformer, are you referring to a passive DI box between the two mixers?

 

[Mark Richards]

Silver Strings,
A transformer's main design purpose is to change the XLR mic's impedance from Low to High Z, increase the mic signal by about +25dB, and filter out any cable noise at the High Z input so that the Low Z mic can be used effectively with the unbalanced High Z input.

But it will also work in reverse, converting an unbalanced High Z line level output to XLR balanced Low Z; and reducing the High Z line level signal by -25dB so it won't overdrive the balanced XLR mic input. At the XLR mic input, any noise picked up in the cable run will be filtered out electronically as I described in my previous post. If the High Z line output is TRS balanced, the transformer treats it as unbalanced TS on the High Z end. Since the conversion occurs at the High Z connection to the transformer and the signal is converted to XLR balanced immediately, TS v TRS has no relevance.

A typical basic passive direct injection (DI) box is designed to convert an unbalanced High Z (typically 40kHz) guitar pickup signal to a balanced Low Z signal for connection to a balanced XLR mic input where a long cable run (>15 feet or so) is required. Some advanced design DI boxes may function like a reversed XLR mic transformer.

IMO the least expensive and most practical method is to keep the entire link High Z if the cable run is short. You can use 1/4" TS male connectors on both ends, even if the mixer output jack and the DP input jack are TRS balanced. If the High Z cable run is >15 feet and both devices hve TRS jacks, then TRS male connectors should be used. In either case, set the DP trim pot full left at the line level setting, and use the source mixer level output controls (not the trim pot) to adjust the level coming into the DP.

Hoping not to cause info overload, this post has a bit more:
http://www.tascamforums.com/threads/dp-32sd-source-fader-level.5239/#post-25860

 

[Silver Strings]

Thanks Mark. I took your advice and hooked up via 1/4" TS and all is good. I appreciate everyone's input. Thanks a million. This is a great forum, wish Mackie had one.