MiniDSP Microphone & REW

[RobinKidderminster]

Ordered from France today to play with. Hopefully some expert here to walk me through.

First question - can I just use the laptop or better to use an external sound card. I have a SoundBlaster X-Fi.

Thanks and apart from the neccessary calibration download and the videos available thru RadioShack are there any rooky pointers to get me going please. :cheers:

 

[ellisdj]

With Rew first thing to note you definately need a sound card - and the first thing to do is to make a calibration of the sound card.

I found this very tricky with Creative Drivers - rather than getting a normal freq line you get squiggles - thats because something is monitoring somewhere and causing a feedback loop. Its a nightmare getting it to work

Using an Asus sound card and the Unfified drivers REW works perfectly - I use the Xonar ST but I am sure they will all work fine.

Set it to left channel in REW and not right channel - that can cuase the loop problem when doing the calibration file and further tests.

You will need the calibration file for your microphone - you should be able to get that from the site you bought it from.

I assume you are going to use the mini dsp to filter / eq the bass - when you select the REW EQ section make sure you select the mini dsp under the equalizer.

Now the trick is to not over equalize - you will want to set REW to give you the flattest resposne to your target - THIS IS A BIG MISTAKE - more equalisation is bad, less is more in this regard.

So set your target level of flatness 3 or 4db with no smoothing , the select it to create your filters - then add 1/3 smoothing to the predicted results. Then uncheck each of the filters it has given you and see if they make a big difference. If they dont you dont need them and dont use them

If you want to get the best bass which I assume this is for - then read this guide and set your eq to a hard knee house curve - ignore what you assume a house curve might be like - trust me its the way forward. You need more bass the deeper the bass as your ears hear it at reduced db - hence why big high end floorstanders have so many bass drivers - to go deep and to boost it in comparison to the mid / treble

http://www.hometheatershack.com/forums/rew-forum/6818-minimal-eq-target-levels-hard-knee-house-curve-long.html

You will thank me big time in the long run - a flat bass curve does not work!!!!!!

 

[RobinKidderminster]

Many thanks ellisdj.. I will study your advice alongside the guidance. It wont make complete sense until I get it connected. I will (probably) be posting a record number of posts to hold my hand!

As Arny once said - I'll be back'.

Cheers

PS looking at your Asus it looks like an internal pc card. I hope my laptop/usb SB sound card does the job.

 

[ellisdj]

Its not the card - all sound cards will work its the drivers - XFi drivers are rubbish

 

[RobinKidderminster]

Doing (a little) reading it seems to suggest that I dont need an ezternal sound card with this (usb) microphone. I guess the sound card is not used???? Some conflicting advice. Is this correct please?

And I dont think my V2065 has preamp inputs so not sure how to connect. Does this matter? May need to read more!

Ah. Maybe I can connect laptop via hdmi .....

 

[ellisdj]

The best way I have found is to feed the av receiver a. Digital signal via spdif from your sound card.

but first you have to make a sound card calibration file - you need to plug the line out into the line in - normally 3.5mm to 3.5mm cable. And then click make cal.

Remember select left channel in REW and it's a good idea in the windows control panel click sound - then for the output go into properties and move the balance to the left.

the mic should have a line out which you will plug into the line in on the sound card but it might get power from the USB as it must have a preamp

does that make sense?

 

[RobinKidderminster]

Thanks. It makes sense. I will wait till I get the mic' since it has no line out as far as I can tell. Cheers

 

[hoopsontoast]

Hi,

As per your questions, AFAIK that would work, UMIK into the Laptop, then HDMI out into the receiver.

I have found it a really easy tool to use, and make sure you calibrate it before you use it (like I didnt, oops). You can input the serial number into the MiniDSP website and it will generate a calibration file, which you input to REW.

An example, comparing DSP to minimal filters:

The DSP one sounds terrible, even with the roll off it sounds a lot better.

 

[RobinKidderminster]

Thanks hoops. Will be asking lots more soon!

 

[ellisdj]

Sounds like hoops can help you more directly.

It also sounds liek the minidsp people give you the calibration file for the device so that makes life easier

Select hdmi out and mini dsp in in REW - hope that your levels are good - but again you will need to switch the balance to left in Windows sound properties otherwise both speakers will play.

It migth not be so imprtant if you are only measuring your sub - as you can select to use the sub to get your level.

I would suggest when you set the level for your sub set it at 80/81db - 75db is quite low. However if measuring speakers 75db is fine

 

[RobinKidderminster]

Thanks again. My phallus has yet to arrive. 🙂

 

[RobinKidderminster]

MiniDSP mic' connected. Laptop to Yamaha thru hdmi. First measurement after some Win7 fiddling. Now? Assuming I can get some free time! Set to stereo + sub with no processing to get baseline measurement? Measure with some amp dsp/crossover settings? Measure the sub on its own using its built in notch filters? Measure each speaker and compare in the asymetric room? Check the centre speaker output by connecting to a front channel? My aim is to use the amps eq to flatten the response for f/l/centre & use the subs filters to smooth the low end. And further to check the centre & to look at the crossover frequencies. Does this sound like a (feasible) plan?

 

[RobinKidderminster]

A quicky? 'In windows turn volume down on one side to hear one speaker'?? Will it harm amp to disconnect the speaker(s) not required and the sub off to isolate just fronts? I guess when the amp is set to stereo and fronts + sub are indicated (rather than the full 7.1) then the speaker output is still eq processed (PEQ or GEQ or off in graphic equalizer)? And I guess the tone controls too

 

[RobinKidderminster]

Some measurements to analyse. Little to compare tho in real world results. Seem to have a nasty dip around 160hz which wont disappear with eq settings. Mains seem to be a bit better tho. Lots more to do especially trying to get a natural centre.

 

[ellisdj]

What do you mean by a natural centre?

I will give you my advice again - its easy tol look at the results in REW and then EQ as much as possible to try and get the results to match the line it gives you as a target.

This is a mistake - EQ as least as possible - and I personally would never boost Freq's - I would also never eq around the crossover point

 

[RobinKidderminster]

Thankx again ellisdj. Taking ur advice onboard. My only concern was a significant dip around 160hz which seems untouchable and I have no idea where it comes from. The room? Room treatment? My centre / natural is my effort to get the centre as accurate for speech as possible. Strangely maybe, in applying a very modest eq to the fronts seems to have corrected the centre. Still plenty to play with but interesting experiments so far. Cheers

 

[RobinKidderminster]

I guess.an omni.directional mic' should be pointed vwrtically rather than towards the source?

 

[ellisdj]

Yes it's recommended to point the mic straight up

a dip in freq response can be caused by several factors - room dimensions is generally the cause and lack of absoption at that freq - 160hz will probs require you to treat a lot of corners - not easy in a living room otherwise I would have done mine 🙂

if it makes you feel better I have several nulls

big one at 80hz on all speakers inc the sub so cross my sub over at 90- I have a nasty dip on my front L speakers in the 150hz region and above.

analysing REW can be soul destroying - but I would concentrate on removing big peaks don't worry about dips- do not boost freqs it will most likely make things worse.

try to eq as least as possible - in my experience the more you eq the thinner the sound gets - not good. If it doesn't make a big diff with 1/3 smoothing you probs don't need it

Seriously try the sub set to a hard knee curve once you are confident - it doesn't sound like you would expect - it's clean and smooth no boomy like you might think from a house curve 😉