Author Topic: SVU-1 Calibration affected by heat? (Read 6696 times)

blu666z · « **on:** April 08, 2005, 07:12:36 PM »

Been having a little issue with my SVU-1 lately and wanted to see if anybody else had experienced it. I have been calibrating my SVU-1 out of my bag. I set the first red light to match up with the -3db light on the UA-5. What I have found is after about 20-30 at a show, the SVU-1 will light up both red lights fairly brightly before the UA-5 light is coming on. Does it make sense that a build up of heat in the bag from the UA-5/JB3/SVU-1 could be affecting the metering of the SVU-1? If so, I can easily rememdy it by letting everything warm way up before I calibrate it, but I wanted to make sure I was on the right path before I did.

-Kevin

mmmatt · « **Reply #1 on:** April 30, 2005, 09:39:53 AM »

I never had that issue with mine, and I used mine (svu-2) a lot in my bag. Are you connected to your ua-5 or to your recorder?

Matt

blu666z · « **Reply #2 on:** April 30, 2005, 12:41:08 PM »

mmmatt · « **Reply #3 on:** April 30, 2005, 10:28:39 PM »

Quote from: blu666z on April 30, 2005, 12:41:08 PM

UA-5

This leaves room for error. First off, the headphone out shares an amp with the rca outs, so if you are patching someone out of either, then your are reducing the signal to the svu. Secondly you have adjustments for the output of the rca and headphone amp, and there is a monitor button that does something... can't remember exactly what though. Your best bet all around is to run the svu off of your recording device. This will help with a consistant level, monitor the level of the recording directly, and it is a great way to troubleshoot your recorder. I assume you are using a jb3? If the lights ain't flikerin', you aint recordin'!

Just my 2 cents.

Matt

blu666z · « **Reply #4 on:** April 30, 2005, 11:04:52 PM »

I would still have the same problem of the calibration changing no matter of where it is in the line.

-Kevin

mmmatt · « **Reply #5 on:** May 01, 2005, 02:46:43 AM »

Quote from: blu666z on April 30, 2005, 11:04:52 PM

I would still have the same problem of the calibration changing no matter of where it is in the line.

-Kevin

if it is heat, yes.

Matt

*edit* you may want to post this question on the team svu-x thread, and see if anyone else is having this problem.

blu666z · « **Reply #6 on:** August 04, 2005, 10:58:37 PM »

Update. Been working on recalibrating the SVU tonite. I only had the left RCA jack on the back of the SVU connected and the REC Source button on the UA-5 set to Analog. If I turned the right gain knob on the UA-5 it would affect the left meter on the SVU. ie. The right gain was at minimum and I had the left gain adjusted to have the SVU at 0 DBs. If I turned the right gain all the way up, the left meter on the SVU would jump up another light to +3 DBs.

By setting the REC Source to Digital, moving the right gain on the UA-5 had no effect on the left meters. Some sort of bleed through in the UA-5 when you have it set to Analog.

Can anyone explain or confirm this?

-Kevin

dklein · « **Reply #7 on:** August 05, 2005, 10:11:33 AM »

Quote from: blu666z on August 04, 2005, 10:58:37 PM

Can anyone explain or confirm this?

-Kevin

Was the monitor button lit? - try again with monitor off.

blu666z · « **Reply #8 on:** August 05, 2005, 11:16:33 AM »

Monitor was on, default when unit is turned on. I'll try again tomorrow with it off.

-Kevin

willndmb · « **Reply #9 on:** August 05, 2005, 12:01:38 PM »

can't really help you with the issue but i know 99.9% of everyone i talked to said use the svu and jb3 line out, not the ua5
so as mentioned that could be part of the prob

blu666z · « **Reply #10 on:** August 05, 2005, 12:43:20 PM »

As long as the UA-5 is used with the same settings as it had when you calibrated, you should be fine. My problem is that the SVU was calibrated with the REC source in the digital position but that later got set to Analog. Why add the JB3 between the UA-5 and the SVU-1? Seems like that just adds another layer of settings that you have to keep the same as when you calibrated it.

-Kevin

willndmb · « **Reply #11 on:** August 05, 2005, 01:30:16 PM »

well i was told that if you use it at the end, you will have the exact settings everytime
and if for some reason one of your parts isn't working right you will prob notice sooner because the svu will not light up
for example if the jb3 stops working with the svu before it you will not know because the svu will still show activity, but if the jb3 stops working and the svu is last you will see because the li8ghts will stop working too

blu666z · « **Reply #12 on:** August 05, 2005, 03:26:56 PM »

Good point.

-Kevin

mmmatt · « **Reply #13 on:** August 05, 2005, 03:32:31 PM »

I tend to beat this one like a dead horse, but you are monitoring your recording and not your pre. It only makes sence to connect to the recorder.

Matt

blu666z · « **Reply #14 on:** August 05, 2005, 04:09:59 PM »

Quote from: mmmatt on August 05, 2005, 03:32:31 PM

I tend to beat this one like a dead horse, but you are monitoring your recording and not your pre. It only makes sence to connect to the recorder.

Matt

I am feeding the JB3 an optical signal so there should be no difference correct?

-Kevin

mmmatt · « **Reply #15 on:** August 05, 2005, 04:57:03 PM »

What makes you think the l/r output of the adc is perfectly ballanced to the analog out of the ua5? End of the chain is the only place where there is not room for error... slight as it may or may not be.

Matt

blu666z · « **Reply #16 on:** August 05, 2005, 05:16:11 PM »

Quote from: mmmatt on August 05, 2005, 04:57:03 PM

What makes you think the l/r output of the adc is perfectly ballanced to the analog out of the ua5? End of the chain is the only place where there is not room for error... slight as it may or may not be.

Matt

I have to assume that the -3db light does what it supposed to and that is what I am calibrated against.

-Kevin

dklein · « **Reply #17 on:** August 06, 2005, 08:36:59 PM »

Quote from: mmmatt on August 05, 2005, 04:57:03 PM

What makes you think the l/r output of the adc is perfectly ballanced to the analog out of the ua5?

It's not...
The analog out is affected by 2 things which DON'T affect the digital output (and can lead to bad readings after you've calibrated
1) monitor switch (on/off, should be off, pain in the butt since it defaults to on)
2) output level (the one above the headphone jack)

And if you accidentally leave the monitor button on, then the monitor volume level becomes the 3rd factor that changes analog output level without affecting digital output level.

So yes, the line-out of the JB3 would be the best place to run the SVU for consistency. The down side is it *might* shorten the JB3 battery life a little bit as the JB3 is now driving an additional load.

blu666z · « **Reply #18 on:** August 06, 2005, 08:52:28 PM »

The only thing I don't understand is, if the UA-5 is run with the setting consistent with how they were when it was calibrated, what does it matter? Consistency is the only thing that bit me this time because I didn't realize the REC Source button would change the output on the RCAs.

-Kevin

willndmb · « **Reply #19 on:** August 06, 2005, 09:47:34 PM »

i personally don't think you need to run the svu nonstop if jb3 battery power is an issue
chances are after a few songs are are not going to change the levels and could turn off the svu anyway

dklein · « **Reply #20 on:** August 06, 2005, 11:03:09 PM »

Quote from: blu666z on August 06, 2005, 08:52:28 PM

The only thing I don't understand is, if the UA-5 is run with the setting consistent with how they were when it was calibrated, what does it matter? Consistency is the only thing that bit me this time because I didn't realize the REC Source button would change the output on the RCAs.

-Kevin

I guess it doesn't matter if the setup is consistent. But that means no movement of dials and you have to remember to turn the monitor button off every time you power it up. I don't think you can properly calibrate with the monitor on.

blu666z · « **Reply #21 on:** August 06, 2005, 11:35:31 PM »

Quote from: dklein on August 06, 2005, 11:03:09 PM

I don't think you can properly calibrate with the monitor on.

Why? I calibrated mine with the monitor on since that is the default...again, if it's consistent.....

dklein · « **Reply #22 on:** August 07, 2005, 12:07:07 AM »

You tell us - does it work or not? Sounds like you're having some trouble. With the monitor button on, any gain changes you make affect the signal twice. Once on the jumpered path and once thru the monitor path. I wouldn't think that's linear. My guess is the higher the gain setting, the more the SVU and JB3 drift apart, with the SVU displaying artificially high levels. Just a guess.

Enough guessing - time for you to test it.
Take some FM hiss from your stereo and use the headphone out > UA-5. Confirm the monitor button is on and adjust the UA-5 input until you're at a steady -3dB or something like that (as read on the SVU). Record it. Now drop the volume on your stereo and turn the UA-5 gain up until you're back at a steady -3dB on the SVU. Record it. Compare the levels on the 2 recordings.

blu666z · « **Reply #23 on:** August 07, 2005, 01:52:38 AM »

I thought the monitor switch only affected what was output through the headphone jack on the front of the UA-5.

I'll try and run the test you suggested tomorrow.

-Kevin

mmmatt · « **Reply #24 on:** August 07, 2005, 12:35:39 PM »

Quote from: blu666z on August 07, 2005, 01:52:38 AM

I thought the monitor switch only affected what was output through the headphone jack on the front of the UA-5.

I'll try and run the test you suggested tomorrow.

-Kevin

the headphone jack and the rca out on the ua5 share the same amp... it is a split signal going to both. This is why many people give an analog patch off the ua5 from the headphone jack... yet another thing that would screw with your metering if you choose to patch from your ua5.

Matt