I have a delta 1010 that has the option to switch between +4 or -10. I had been experimenting and set the delta to +4 connected to a preamp (Peavey VMP2) a while back. I didn't notice it at first, but there was a underlying distortion happening and built up more as I added tracks. It was so slight that I had to really listen intently to hear it. I thought the preamp or the delta was aging and losing their vibe or maybe a new mic was in order. 

Yesterday, I switched to the -10 setting on the delta and had to lower the gain on my preamp (head scratcher - makes no sense to me) and the sound I wanted was there (smooth as in very smooth). On one hand I'm happy like I just bought something new and top quality - but what puzzles me is I am under the impression that +4 would be a more pro or cleaner sound and the preamp gain would be lower, not higher. 
 
I'm happy and frustrated at the same time - many projects have been completed with my user error settings. I feel like I'm working in a "go for it works", but don't really understand why it works.  I've been at this for years, but sometimes I still feel like a rookie. 

Anyone would care to comment. 



Thanks

+4 is a positive number, 4 units above 0. -10 is a negative number, ten units below 0.

Just kidding. They are voltage level standards, i.e. they define what range of voltages are used to represent the signal accepted and sent out. Most pro (and generally most semi-pro) equipment use +4. Probably your VMP2 does but check the docs. You should set your Delta to +4 unless you know you are using -10 gear since it's pretty certainly that it's going to be +4 if it's not consumer level gear. Some of it may have an optional setting. If so, set it to +4 on everything.
 
Setting the Delta to -10 makes it more sensitive, so the +4 signal that it's receiving is being treated as a higher level signal than it really is. It's not good gain staging because you are running a lower source signal into the Delta and then cranking it up. You generally would want the other way. You want to get a good signal into the mic, which gets you a solid signal into the preamp with the least input gain required, which gets you a good signal into the converters with the least output gain required. That makes for the best S/N ratio.
 
You could have possibly been overdriving the input of the Delta a bit perhaps and causing some distortion. Or it may have been something else, hard to say.
 

Nice joke, you have my kind of humor!

Without really knowing, that is why I used the +4... You are spot on with the -10 being more sensitive. I will experiment some more and try to make +4 work if it indeed would make for better gain staging = clean sound. 
Thanks for your thoughtful help. 


Thanks Dean!

Okay - more testing and it seems like I'm missing something.

Selecting +4 on the delta with same preamp settings produces a much lower recording gain-wise than -10. hmmmm  

The sound I'm recording with the -10 setting is very nice/better, the only big problem is I have to really watch for overages. I have one more thing to check, the delta 1010 inverts the signal on the -10 setting. They correct this at the driver level and I have that correction check marked. Later today I'll try again with that box unchecked.

Unless something else is screwed up, you can just go w/ the -10 and hope you don't blow out speakers or something. ;-)

But maybe something is wrong w/ the vm (I'm assuming it is +4).  +4 into -10 should mean the vm is needing to run very quiet, so the input gain and output is turned way down.  Maybe a problem w/ the tube if running at normal levels brings up distortion?

@

Some of the confusion may stem from the difference between specifying output versus an input settings. 

If you were configuring the output of a device such as a mixer, +4 means the mixer is going to send out a hotter signal (higher voltage) than if you had set it to -10. This is considered the "pro" standard because the higher amplitudes mean better S/N ratios and longer cable runs.

A +4 setting on an input tells the device to expect to receive the hotter +4dBu levels, so the gain at the input channel is going to be lower than if you'd set it to -10. Setting the Delta to -10dBu would cause its gain to be higher, in order to accommodate the lower -10dBu levels.

-10 is actually -10 dbv not dbu. There is a different reference level involved. The dbV setting relates to 1V as the ref level where as dbU uses the 0.775 v as the ref level. -10 dB V is actually -7.8 dBu just to add to the confusion. +4 dBu always relates to the dBu ref level.

But for most purposes what people are saying here is still correct in that -10 is a more sensitive input but a lower output and +4 means higher signal going in and louder signal coming out.

It does not matter which you use as long as the signal that goes into your soundcard matches the input setting you have chosen and the level coming out of your soundcard also matches well to the equipment it is connect to. BTW some sound devices allow you to select a different setting for input and output levels. This is handy as it allows you to better match your input and output levels to the various devices that are feeding it and what the sound card is driving.

All this is starting to make sense. Thanks to all of you for helping me understand this. The Delta1010 does let you choose +4 or -10 for both the input and output.

When I'm running at +4 input, I have to drive the vmp2 to get a strong enough signal and even then, it is recording a weak signal around -36 db. And it has underlying distortion. Maybe there is an issue with this unit, I don't know. I bought it new many years ago.

For right now, the smoothest and cleanest signal to my ears is -10 input with +4 output on the delta. With the overly sensitive -10 input (which I didn't understand prior to today), I have to watch overages with vocals. Minus that, it sounds outstanding and the recorded signal is coming in strong around -12 db. 

My wish would be to have +4 on both input and output. Jim Williams of audioupgrades lives in a neighboring city, I may drop the VMP off there for testing.

Thanks Again!

Hi Dave. Well I downloaded the manual for this unit and it looks pretty good actually. It says the nominal output is supposed to be +10 dBu and a maximum output of +20 dBu. Now these seem like pretty decent output levels so one could expect to be able to get a decent level going into your soundcard even with the +4dBu input setting which is what I would definitely use in this case. I also see that even the high Z unbalanced outs are sporting exactly the same levels as well.

I see there is no separate output level control so I assume you get this output level by setting the input gain accordingly. Usually when there are balances output connectors on anything the levels there are +4dBu. I assume you are leaving the Hi and Lo controls set flat.

So what happens when you set your soundcard to +4dBu (input) and just keep increasing the input gain until the desired level is reached going into the Delta. The input pad should also be OFF. Is it BTW? If the PAD is on then your output level is going to drop 20dB hence the nominal output goes from +10dBu down to -10dbu which could explain things. Under normal conditions the Peavey should easily drive  +4dBu level nicely into the Delta without any distortion as +4dBu is already 6dB down on the nominal output level (+10dBu) so it should be easy to get there.

If your PAD is OFF as it may well be it might be good to have the Peavey checked out. Sounds like it is working but for some reason your output levels are way low hence the reason you have to go down to -10 on the Delta input in order to get anything going in properly. You should be blasting the Delta even on the +4dBu input setting easily.

One thing that should be asked is, what are you recordng and with what type of microphone? If you are using a ribbon or dynamic (which are typically fairly low output mics), and the source you are recording is fairly low volume, then you aren't probably going to get a lot of signal out of it unless it's cranked up pretty high. You need to give them some reasonable volume in the room. Phantom powered condensors have more oomph, and typically self-phantom powered ribbons with their own external power supply have that much or more, and will require considerably less gain on the pre-amp.