Speaker design/test software

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simon
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Re: Speaker design/test software

Post by simon » Sun Oct 20, 2019 7:04 pm

Watching with interest Mark. I'm seriously thinking about triamping with low pass and high pass filters within the amplifiers and it might be a bit approximate doing it by ear.

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Re: Speaker design/test software

Post by IslandPink » Fri Oct 25, 2019 3:10 pm

I've got all the bits but it'll be clip-lead city, owing to how I've only got the bi-amping set up via the phono amp, currently. I'll get REW on the laptop and have a look at the layout of everything this evening.
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Re: Speaker design/test software

Post by chris661 » Sat Oct 26, 2019 11:27 am

simon wrote:
Sun Oct 20, 2019 7:04 pm
Watching with interest Mark. I'm seriously thinking about triamping with low pass and high pass filters within the amplifiers and it might be a bit approximate doing it by ear.
Gimme a shout if you'd like me to bring some measurement gear round.

Chris
If you can see the cone move regularly, you haven't got enough speaker.

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Re: Speaker design/test software

Post by simon » Sat Oct 26, 2019 11:38 am

Thanks Chris!

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Re: Speaker design/test software

Post by IslandPink » Sun Oct 27, 2019 5:28 pm

OK I've got the kit set up, but a brief try at getting some sound to come out of the speakers has failed so far. I need to read some sort of basic guide, I just hoped it would sort of become clear what to do :) but it hasn't. More application required by the student.
Any tips appreciated, Chris.

ps. I did hear a test signal coming out of the Laptop, so maybe I need to edit something on the control panel to tell it to send audio out via the USB ?
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Re: Speaker design/test software

Post by IslandPink » Sun Oct 27, 2019 7:30 pm

Should just re-cap on what I have done :
-Installed REW on the laptop.
-Downloaded the driver set for UMC202 from Behringer
-Connected the UMC to the laptop to complete the driver installation process.
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Re: Speaker design/test software

Post by chris661 » Sun Oct 27, 2019 8:10 pm

Preferences (spanner at the top right) > Output Device > select the UMC soundcard

Same for input device.
Should get you going.

Chris
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Re: Speaker design/test software

Post by IslandPink » Sun Oct 27, 2019 10:11 pm

Thanks, I'll have a tinker tomorrow.
Weekend has been dominated by toothache, hoping for an emergency appointment tomorrow if I can get one !
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Re: Speaker design/test software

Post by IslandPink » Mon Oct 28, 2019 8:05 am

There's stuff that pops up about calibrating SPL ; then in the blurb also about calibrating the soundcard. Are these things I need to do, or not ?
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Re: Speaker design/test software

Post by chris661 » Mon Oct 28, 2019 9:37 am

Calibrating SPL just means the vertical dB scale is accurate. ie, the speaker actually produced 90dB at 50Hz, 84dB at 1kHz, etc etc. Not of particular importance for you IMO. Your measurements might read 70dB at 50Hz, 64dB at 1kHz. Not a big deal.

The soundcard calibration probably isn't necessary either - it'll just show REW the HF and LF rolloffs on your soundcard. IIRC the UMC range are something like -3dB at 5Hz, so again, not of particular importance.

IIRC, REW was originally made for the home-theatre crowd, where some of the nutters are trying to get flat to 5Hz (or lower), so correcting for the LF rolloff of the soundcard is of importance.

Chris

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Re: Speaker design/test software

Post by IslandPink » Tue Oct 29, 2019 8:19 pm

Had a few mins just now and had a further test.
This time, progress, up to a point. Thanks for the tips, Chris. Got the input/output sorted via REW. One thing you didn't mention is it seems to default to the R-channel jack output when there's only one lead connected. Swapped it from L to R and got sound to come out of the speaker :)
However, microphone doesn't seem to be picking up much as the graph is very low and REW is complaining the data level is too low for useful results.
This picture could have been better. I do have the 48V switch ON at the back and the knob turned up on the front. Anything else I should check ?
Is the UMC202 sensitive enough to deal with the Behringer mic output without a pre-amp ?
REW_UMC_first.JPG
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Re: Speaker design/test software

Post by chris661 » Wed Oct 30, 2019 7:45 am

Looks like you could run the input gain much hotter. The UMC soundcards get slightly noisy towards the very top of the range (3 o'clock up to 5 o'clock where they max out), but anywhere up to there should be fine.

If you click "measure" and then "check levels" it'll give you an idea of how things look. IIRC REW wants the incoming level to be at -35dB or it'll complain. So, use the input gain knob to get that number somewhere good.

Chris
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Re: Speaker design/test software

Post by IslandPink » Wed Oct 30, 2019 11:42 pm

Turned both knobs up to full, has improved, but still about 20 or 30dB short of where I need to be. I was hoping not to turn up the amp system above where I was using it, because I wanted to check what my ears had said was correct ( I need to turn up two amps independently ) but I guess I need to do that now.
I have played around with some of the other push-buttons but I have not got anything positive from that.
More tests on Friday.
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Re: Speaker design/test software

Post by chris661 » Thu Oct 31, 2019 10:59 am

All the other buttons should be in the out position - one of the buttons is an (IIRC) -20dB pad on the input, which is used for when you're recording something very loud and don't want to overload the input. For your application, never ever press the "direct monitor" button - it feeds the input straight through the soundcard to the output, which will result in mic feedback. PA speakers are designed to suck that up for a minute, but HiFi drivers can be considerably more fragile so there's a risk of damage. You'll notice the loud noises, though.

An ECM8000 into a UMC202HD should be able to get plenty of signal into REW. Remember, it wants to see somewhere in the -20 to -30dB range on the input when you press the "check levels" button. If REW says "Level OK", you're good to go.

What sort of level are you testing at (ie, v.quiet, speaking volume, shouting volume?), and what's the distance to the mic?
Oh, and what's the sweep level set to on the measurement popup? I don't know what the default is, but you can get some more gain there.

Chris

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Re: Speaker design/test software

Post by IslandPink » Thu Oct 31, 2019 3:40 pm

I will comment more later, just at work.
Results i was getting last night were about -60dB ( up from -80dB )
Think the buttons are all out as they should be - checked on those.
You may be right on 'sweep level' though - hadn't spotted that. That's on REW ? Test squawk comes out at a moderate listening volume - was expecting louder.
Microphone was about 1m.
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