Yep I realise this but still...mic is dissapointing I'll go probably for Earthworks M23..Axis D-Audio sound card seems to be the best solution for sound measurements...

http://www.duran-audio.com/pdfs/downloads/d-audio/D-Audio_1.2.pdf

That looks fine, though I'd prefer a sound card that supports USB 2 and 24-bit recording. Not that you need more than 16 bits for room testing! But if this sound card is inexpensive then go for it.

Hi, all
I'm hoping someone here had a similar experience or has worked with the same Tascam USB device.

Here's what I'm trying to get set up for room measurement:
R+D on a laptop with Vista home premium.
External Tascam US-122L USB interface.
Behringer ECM8000 omni condenser mic.
Single self-powered monitor speaker to play the test signals.

I haven't been able to get this working so that the auto mic-spkr distance measurement is correct AND I have a decent S/N ratio.

Initially, running the loop test with auto mic-spkr distance set, I would get like 234m. With a regular measurement, it would come out to 900+m. If I tried to run the measurements with manual mic-spkr distance set (0 for loop test, 1m for regular measurement), R+D would crash.

Doug has been looking into this for me, and feels it's a driver issue. I've got the latest driver and firmware update installed from the Tascam website.

The last thing I tried was to set the latency to "Lowest Latency" setting on the Tascam interface. With this setting, I was finally able to get the auto mic-spkr distance to work.
However, the best input signal S/N I can get is about 14dB.
That's tweaking the output level and mic gain settings on the Tascam to try to find an optimum setting. That's the best I can get; deviating from those settings, the S/N either gets worse, or the calculation of the mic-spkr distance fails again.
Also, on that latency setting, I'm getting some clicks out of the interface.

I did see in another post that someone solved their S/N problem by unplugging the AC power; I'll try that next.

Otherwise, anyone have more suggestions? Is this Tascam US-122L a POS interface? I'd like to avoid buying a different interface if possible. I bought this specifically for this purpose, and wanted one with phantom power for a condenser mic.

Is there any possibility this could be cables? I've got a mogami mic cable, and an instrument-type cable for the line output to the monitor speaker (and also for the cables for looping in to out).

Thanks for any help! I want to get this up and running and get on to the real fun of learning to use it!

Does anybody here use the Soundblaster USB MP3+ (or similar)external soundcard, AND a condensor mic, with R+D?

If so, what are you using to provide phantom power and connect the mic to the Soundblaster?

Thanks

Hi Ethan,
I read elsewhere in this thread that you're using an omni condenser mic, and a Firebox with R+D. This would seem to be a very similar setup to what I'm using (other than firewire vs USB computer interface).

Have you run into any problems with that setup? Poor S/N ratio, incorrect mic-spkr distance calculation, or crashes as I described a couple of posts earlier?

Keith,


This is definitely a question that Doug can best answer. I will mention that many (most?) receivers have some amount of delay built into the signal path, and this is the likely culprit. Not sure why distance even matters though. Are you using a receiver?

Regardless, if your sound card basically works, and it works for all other applications, the driver is probably fine.

--Ethan

Yes, but the FireBOX has phantom power.


I have had poor s/n, but only with the composite test signal. If you switch to the swept sine wave you should be able to get 40 dB or better.

--Ethan

Receiver as in stereo receiver? No, I've got the soundcard line out going to a powered monitor speaker.

Yep, the Tascam US-122L also has phantom power on the mic inputs; that's one main reason I went with that type of unit.

Wow, your "Tele-Vision" video is cool. The only thing I did not see you playing was drum kit. I'd guess that you could, though, you appear to be a very talented individual!

Keith Carlson: "With this setting, I was finally able to get the auto mic-spkr distance to work.
However, the best input signal S/N I can get is about 14dB."

This is very strange. Could you email me this measurement ?

Can you send me an electrical block diagram that shows exactly how this is all connected ?

"Not sure why distance even matters though."

It doesn't really - RPlusD will tolerate more than 100 ms of path delay.

Doug, thanks for your support on this.
I'll hold off on the email for now. I tried R+D with the Tascam interface and same mic, cables, etc. on a desktop computer running XP, and it seems to work fine there. S/N ratio of 35dB and consistently accurate mic-spkr distance.

All I can think of is it doesn't work well with this Vista laptop (although I don't understand *why* it doesn't).

Vista takes up about 67% of the 1GB of RAM just starting up, with no apps running. I'll be adding a gig of RAM to see if that makes a difference.

Thanks Keith. I wrote and "performed" the drum part as MIDI, and I planned to fake the playing when I got to the video part. Then a few days before we were going to shoot the drums I came to my senses and realized there was no way I'd be able to look convincing in front of a drum set. So I had my friend Ed Dzubak fake it for me.

--Ethan

Ethan,

I love your videos. Where is the Tele Vison one ?

Never mind - I see the link.

My bird really likes you videos. He also likes Jethro Tull & The Beatles.

He started wistling and even gave me a kiss for playing it !

Yes, but the FireBOX has phantom power.

Hi, Ethan
From what I know of your setup to use R+D, I assume that your microphone is plugged into the FireBox's Mic In, right? Not into a Line In jack?

I've done it both ways. When I used to use a Radio Shack SPL meter I'd plug in into the FireBOX's line input. With my AKG C451 or my newer DPA 4090, I use the microphone input with phantom power. Both have always worked fine.

--Ethan

Maybe a stupid question...But Ethan, in your Firebox do you use a loopback connection with phantom power ON when making measurements? R&D requires this connection anyway but...mic meeds phantom as well! Should I be confused with that or it is just a matter of using a mono 1/4 jack which anyway will "cancel" the 48V from the power supply?

Thanks,

Harry

Phantom power is not applied to the 1/4 inch inputs, so it's okay to have it on for the microphone.

--Ethan

Hi,

maybe someone can explain this to me.
My question is about the normal frequency plot that every measurement software can produce from a log sweep.

What moment in time in relation the moment a frequency is sent out does the respective part of the plot represent?

When I compare it with waterfall plots, the frequency plot resembles the first layer in time.
From this I'd estimate that a frequency plot shows how loud a frequency is about 30-50 ms after the frequency started playing? Is that about right?

Greets

I assume the FR plot is the steady-state response, after any resonances have built up fully. But I'll be interested to see what Doug Plumb has to say.

Should have done this earlier but now I looked in the manual of R+D and it's explained there.
The term for this time span is Gate Time. When you have a gate time of e.g. 50 ms the lowest frequency you could measure would be 20 Hz, because the frequency must have enough time for at least one circle during the measurement.
The default for ETF seems to be 100 ms (for a low frequency response).
I guess that's enough for resonances to build up. At least in small rooms.

Can I make a request that RPlusD be it's own sub forum rather than just a sticky thread. I understand it's not had a huge amount of bandwidth. But I think the fact that it's just a single sticky is part of the reason. It seems the tool is vast enough that it needs it's own forum. Look at the REW forum, it's huge. I think RPlusD could be just as huge a forum.

Can someone explain how I export my Filters.

I see them in the box in the lower right corner but when I goto File Save menu and save them the file has no filters.

Am I missing step?

Thanks

I figured it out, I needed to manually add them.

Does anyone know how to set RPlusD to not make use of Filters that boost (when doing the automatic EQ fitting)?

My Meridian Preamp can only do attenuation.

The Corrected curve looks good but it includes a lot of boost filters (Z's). With these Z's removed it looks like crap.

Am I missing another step?

I agree but it's not my choice. I don't own this BBS, so this was all I was able to offer.

--Ethan

Hello,

I'm an infrequent user of EFT. Yesterday I loaded RPlusD, setup a Firebox and was preparing to test my control room again to get some familiarity with RPlusD. The last thing I did yesterday was fill in the registration.

Today when I opened RPlusD I went to File > New > Normal Room/Speaker Measurement and received a run time error '9' and RPlusD closed.

I couldn't find run time errors in the index, or the manual so tried to backtrack, reloaded my license, reloaded the software, etc. Then I turned to the web, found this forum, thank you.

While I didn't find a post about run time error '9', I eventually reviewed tool bar options, and turning off the mixer in Options > Mixer > Mixer Off seemed to clear up my problem.

So I wanted to post this in case someone else trips up in a similar fashion.

Question: Is there a listing somewhere of the definition of run time errors?

Thanks

Does anybody know how to print from the large room window?

I guess I just figured it out, you have to close the large room window, go to file, graphic export, and a large room graphic export is available. It seems to print whatever was last viewed.