External Pre's through Inserts

[Neil Eckstein]

How?

Hey All. I'm new to the forum. There is a TON of awesome information on here and I'm pumped to find so many people who care about helping each other!!

This might be a simple one, but I'm willing to admit my ignorance here.

I noticed that someone else was having an issue with clicks and pops being printed to the recorded audio. His solution won't work for me.

Right now I'm routing a Neve 511 and an API 512V via XLR into the additional 1/4 in TRS on a UA 4-710d and then sending all of that ADAT to the DM-3200. I've got the routing figured, but I'm getting some drift somewhere; I know it's a clock issue, and I'm sure I could get a master clock and that might fix the problem, but honestly I don't need that. Really I would just like to send the analog signal from the external pre's into the inserts on the DM so that my conversions are happening in one place.

How? I just don't see how to do this. Is it possible? What are the settings to make it happen?

 

[Neil Eckstein]

OK so I routed the outs from the Neve to the Insert on the board and it just works. However, I noticed that the pre on the DM is still coloring the signal. Is there any way to bypass the preamp circuitry on the board?

 

[Clinter]

I'm pretty sure that the insert bypasses the Mic pre; the channel trim has no effect on the insert input. You would loose a little gain because the insert is unbalanced. That may be why it seems "colored" by that routing. You could always route the mic pre to one of the Assigned Return inputs on the DM. In my experience, that probably would not sound much different, though. I'm using an old ADAT HD24 as a digital patch bay to get external Pres into my DM via the light pipe. The HD slaves to clock via the DM's ADAT output without any problem, and the conversion sounds great.

 

[Arjan P]

Yup, what Clinter said, see here:

 

[Neil Eckstein]

Wow. I truly appreciate the speedy replies! Thanks!

The reason I said what I did is because I noticed that if I cranked the pre on the same channel where I'm inserting, it prints the noise floor of that pre to the audio.

So, I guess the better question is: should I change the input routing on the channel to which I'm inserting to NOTHING so that the preamp has no effect whether engaged or not?

Also, how does the board know which insert goes to which channel? If I don't specify in the insert menu then it goes direct. Can I change where it goes by simply changing the channel routing in that insert menu? And more importantly, does that mean I can use e.g. channel 1's preamp with mic/line and then also use the insert (with a different pre) routed to a different channel?

Again, I really appreciate the info. I've NEVER posted on message boards before because it's usually pointless. You guys are a different story though. Thanks a lot!

 

[Clinter]

In your original post, I had assumed that you were referring to the hardware inserts in the back of the DM. Those are, of course, hardwired to their respective channel. The Insert function that is part of the Routing menu on the DM is a whole different animal. The software Insert, if my understanding is correct, assumes that you already have a signal that has been processed by a mic pre and are simply routing to another external processor like an EQ or a compressor. If you strap in an external mic pre as part of the software Insert routing, you are essentially re-amping your signal, which I think is not what you want to do. Even if you can by-pass the original mic pre input, you are still adding an extra D/A/ A/D conversion which is probably not a good idea, either. I would suggest that you use an Assigned Return to get your external pre into the DM. There is definitely no pre amp on the Assigned Returns. The routing would be much simpler than the software Insert routing and your external pre would be going through much less circuitry that could "color" your sound.

 

[Arjan P]

Yeah, sounds like your confusing hardware analog inserts with the digital software inserts (that come with a menu).

Another thought - if we're talking hardware inserts - is the question whether you push the TRS plug fully in. If you're supplying signal to the insert alone, you should push the plug halfway. That way, there is no way the preamp trim can have any influence.

 

[cmaffia]

There are also proper insert send/receive cables you can purchase for this. Another option is getting the Analog Card expansion card if you're planning on adding more preamps.

 

[Neil Eckstein]

Guys. Thanks so much. I ended up just snaking each new preamp to an insert and it's working great. I just have to make sure the board pre's are down.

This forum is awesome. I'll be back.

Thanks again.

 

[cmaffia]

I'm assuming you are implementing an external preamp to bypass the channel's preamp coming into the desk, correct? If that's the case you are going to use the hardware inserts per channel and you would use the INSERT RTN (the RING of TRS) for this signal. I thought that once the INSERT RTN was engaged, it bypassed the boards preamp signal flow and went straight to the A/D converter so I'm a little confused when you say that you have to "keep the board's preamp down". It's been a while since I used the hardware inserts so I may be wrong. I remember experimenting with the hardware inserts to SEND my firewire stems to an analog mixer as well.

 

[Neil Eckstein]

Well when I had them fully plugged in there was no noticeable difference in quality from monitoring the external pre without the board. However, if you turn up the preamp (which brings up the noise floor regardless of anything being plugged in), it prints the inherent noise floor to the track. I don't know why, but it's exactly the reason I was trying to sort this out in the first place.

 

[Arjan P]

OK, so this should eliminate any preamp noise: try using a fully plugged in stereo jack and only supply signal between sleeve and ring contacts (the return side of an insert snake). That way you not only supply signal at the right place but also open the switch contact, cutting off the analog preamp fully. See above schematic.