I don't have such measurements, because I use phase-linear crossovers and I don't need to measure each speaker separately, it's enough to measure three speakers together through the crossover and see on the step response which speaker plays earlier and which one plays later.
In any case, it is much easier and faster to check than to theorize on this topic. Make measurements of the speaker system on the axis, then rotate it by 45 degrees, and then by 90 degrees from the measurement axis, if the time between pulses in all three dimensions remains the same, then this means that you do not need an external speaker to measure the speaker system at an angle. If the angle does not exceed 90 degrees.
Kimmo Saunisto (@kimmosto ) definitely rejects USB microphones, as you can read in this document, for example, where he wrote:
But because REW offers the possibility to set up an acoustic timing reference, I once asked about this in the big VituixCAD thread, see here.
A little later, after some discussion, Kimmo Saunisto conceded that the way I described it is probably a useful method for setting up a timing reference that can be used for USB microphones. The discussion began here (read the following posts too):
However, I have to say that I myself use conventional XLR microphones with a two-channel audio interface equipped with a loopback cable for electrical timing reference because this setup is simply much less prone to errors.
Btw.:
The subject "reflection-free measurements" have nearly nothing to do with timing reference issues.
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That was my comprehension when I wrote "I don't get how the timing reference corrects that".
Thank you for the links.
Well you convince me to look for an audio interface as it seems better and not so expensive.
Just don't know how to choose a mic? It seems most are uncalibrated unlike the UMIK for example. Not a big deal?
As for the audio interfaçe, there seems to be a choice between very low budget (UMC202HD) and very good performance and ok price (Motu M2). Is there something good between them? Is UMC good enough?
Hello Jamproject
I did a very similar project 3 years ago. I had a pair of NOS Eton HEX 11s lying around, bought from Ebay-Kleinanzeigen for a reasonable price. Open baffle never was an option. I already had built ported 3-ways, TMLs and horns. So I decided to put them in a classic vintage sealed enclosure. I spent a long time looking for suitable midrange drivers and tweeters and finally bought dome drivers from Morel (ET 338, EM 1308). I studied the level and frequency response of the drivers in detail so that I would have to make as few corrections as possible. For 3 years they are my favorite speakers.
Why?
I, for the first time, went fully active😉.
A Behringer DCX2496, a calibrated, battery driven Superlux ECM 888, a used multi-6-channel-input Sony-AV-Receiver and a cheap but decent Douk Audio USB to Coax/Optical converter.
Then I sketched the housing with the help of online calculators - "Thiele-Small parameters", built them, calculated basic crossover frequencies and started measuring. And this, as everbody knows, is the most crucial and hard part. I never get used to REW. I'm still using Holmimpulse and playing with the DCX2496 gives you fast response and is pure fun.
All my carpets and cushions were used to make the housing, the 1-m measuring range, as far as possible anechoic. Then, after I found a satisfying flat response curve, I started measuring from the listening position (in a well treated room). Finally I compared the results with a very good headphone.
I was able to compensate for the disadvantage of the closed cabinet in the low bass by parametric boosting below 35 Hz. The Eton chassis does this without complaint.
This project has given me incomparable pleasure and I have learned so much about acoustics. And today, having just finished it, I swapped the DCX2496 for a miniDSP Flex eight. The big smile on my face now: priceless! But that also comes with it's price. Next step: Experimenting with FIR filters.
If you want to go this way: You will have to read a lot but it will give you a huge pleasure to constantly improve yourself and your equipment.
I did a very similar project 3 years ago. I had a pair of NOS Eton HEX 11s lying around, bought from Ebay-Kleinanzeigen for a reasonable price. Open baffle never was an option. I already had built ported 3-ways, TMLs and horns. So I decided to put them in a classic vintage sealed enclosure. I spent a long time looking for suitable midrange drivers and tweeters and finally bought dome drivers from Morel (ET 338, EM 1308). I studied the level and frequency response of the drivers in detail so that I would have to make as few corrections as possible. For 3 years they are my favorite speakers.
Why?
I, for the first time, went fully active😉.
A Behringer DCX2496, a calibrated, battery driven Superlux ECM 888, a used multi-6-channel-input Sony-AV-Receiver and a cheap but decent Douk Audio USB to Coax/Optical converter.
Then I sketched the housing with the help of online calculators - "Thiele-Small parameters", built them, calculated basic crossover frequencies and started measuring. And this, as everbody knows, is the most crucial and hard part. I never get used to REW. I'm still using Holmimpulse and playing with the DCX2496 gives you fast response and is pure fun.
All my carpets and cushions were used to make the housing, the 1-m measuring range, as far as possible anechoic. Then, after I found a satisfying flat response curve, I started measuring from the listening position (in a well treated room). Finally I compared the results with a very good headphone.
I was able to compensate for the disadvantage of the closed cabinet in the low bass by parametric boosting below 35 Hz. The Eton chassis does this without complaint.
This project has given me incomparable pleasure and I have learned so much about acoustics. And today, having just finished it, I swapped the DCX2496 for a miniDSP Flex eight. The big smile on my face now: priceless! But that also comes with it's price. Next step: Experimenting with FIR filters.
If you want to go this way: You will have to read a lot but it will give you a huge pleasure to constantly improve yourself and your equipment.
Hi,
I'm playing with VituixCad. I think that I have done my simulation right but have trouble to say if the result is good enough..
What I did:
Simulation baffle is:
For example with 2th order LR @3500hz between mid and tweeter
With 4th order LR @2000hz between mid and tweeter (wider dispersion but more directivity error)
For this 2 examples, would you say result is good and validate baffle choice? What would be the decision criteria between both for example?
I also consider, for aesthetic reasons, the following design but it seems complicate to simulate and compare with previous? Seems the beveled design works well generally speaking..
As a first test baffle, what would be your choice?
I'm playing with VituixCad. I think that I have done my simulation right but have trouble to say if the result is good enough..
What I did:
- Get on axis response from SB datasheets on infinite baffle for the 3 drivers
- Import the response into "half space response" from diffraction simulator, place drivers with mic centered on each driver and export full space response
- Offset the driver in crossover section and play with filters
Simulation baffle is:
For example with 2th order LR @3500hz between mid and tweeter
With 4th order LR @2000hz between mid and tweeter (wider dispersion but more directivity error)
For this 2 examples, would you say result is good and validate baffle choice? What would be the decision criteria between both for example?
I also consider, for aesthetic reasons, the following design but it seems complicate to simulate and compare with previous? Seems the beveled design works well generally speaking..
As a first test baffle, what would be your choice?