Here are some pictures, Xsim theoretical design pieces, and an outdoor measurement of the MTM pair I designed and built from scratch. Objectively there is room for improvement, but even so I think they sound great (because I made them? who knows ;P ). And I built more than one pair and tried to sell them (which is why I have this Etsy link... I'm not getting rid of them), and it is HARD to sell speakers you've made yourself. I should have known, but I had grand plans.... Ah, well.
Let me know what you think! I'm still learning and building (and have some ideas for the next projects....), and I want to take every lesson I can from this pair to improve the next 🙂
https://www.etsy.com/listing/1478244046/custom-designed-hand-made-hifi-speakers
Let me know what you think! I'm still learning and building (and have some ideas for the next projects....), and I want to take every lesson I can from this pair to improve the next 🙂
https://www.etsy.com/listing/1478244046/custom-designed-hand-made-hifi-speakers
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Nice finish. Decent frequency response to 100 hz. What is not to like?
In a world where sub-woofers are part of 90% of systems, this is a good start.
I like you did the work to install a passive crossover. You don't have to replace the dsp every time the software doesn't match the current phones. You only need 2 or 3 channels of amplifier to power up every hour of use.
What can make your design more significant is doing off axis measurements. Also a harmonic distortion measurement would be informative. My (purchased) system has HD 2nd harmonic 20 db down from response from 60 hz to 12 khz. At 5 watts. That speaker has response 6 db down from on axis at 45 degrees off axis. All frequencies.
In a world where sub-woofers are part of 90% of systems, this is a good start.
I like you did the work to install a passive crossover. You don't have to replace the dsp every time the software doesn't match the current phones. You only need 2 or 3 channels of amplifier to power up every hour of use.
What can make your design more significant is doing off axis measurements. Also a harmonic distortion measurement would be informative. My (purchased) system has HD 2nd harmonic 20 db down from response from 60 hz to 12 khz. At 5 watts. That speaker has response 6 db down from on axis at 45 degrees off axis. All frequencies.
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Cool project! For your first project, you have achieved great performance.
The minimum impedance looks like 2.5 Ohm at 300 Hz. Any problems driving them, such as the amp getting hot or tripping its protection circuit?
The minimum impedance looks like 2.5 Ohm at 300 Hz. Any problems driving them, such as the amp getting hot or tripping its protection circuit?
Keep going. A friend of mine does assorted artistic wood-working projects, so I sometimes get a sneak preview of happens behind the scenes. And let me say: 90% either doesn't sell or it's like pulling hen's teeth. But occasionally, there's a smash hit and there's just no rhyme or reason to it, and he just scales up production x100 for just that one item.
Nice speakers indeed. High WAF with those.
Curious: At what point did you decide to reverse the polarity on this 3rd order XO?
Curious: At what point did you decide to reverse the polarity on this 3rd order XO?
They look great but they look like they could have a lack of bafflestep compensation and the phase coherency through the cover frequency might be lacking.
Thank you Jo! I've attached a measurement comparing on-axis and 45 deg off axis. Huge dip right above 10k hz but I also don't normally listen from 45 deg off, I should have taken measurements from 15 and 30 deg as well but from what my ears tell me, it's more even than the 45 deg is. I'm not even sure how to do distortion measurement, I'll have to do more learning on that!
Thanks, Jim!
I have a 150 watt per channel Sony da7100es which isn't rated for 2 ohms but I haven't had (noticed....) any issues.
I'm waiting for the day! 😀 in the meantime, I need to figure out how I can use 4 or 6 of these in my small living room so they don't sit doing nothing xD
Same! Have you used them in a build? I have a few more I want to put in a full tower/3-way system.
Thank you Cal! I'm pleased to say she likes how they look and sound 🙂
I made the decision during the "theoretical" phase of crossover design (I made it in XSim, then adjusted it in real life with listening tests and then took a measurement and adjusted once more). In Ray Alden's Speaker Building 201, it shows that reversing the polarity of the tweeter in a dual 3rd-order crossover wouldn't change the phase (from my understanding of it, anyway), and it was much easier to get the FRD working with the crossover points that I wanted when it was reversed.
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I placed the drivers with an irrational fractional ration from edge to edge in an attempt to help with the stacking of diffracted waves, but I definitely could have designed the xover to help with that, too.
The phase coherency... is again just beyond my knowledge, so you are most likely right! I'll look into that for the next set I build or improvements to this one 🙂
Nice to see an MTM where care was taken to get the driver centre-to-centre as small as possible.
Thumbs up!
dave
Thumbs up!
dave
Bafflestep compensation flattens response for speakers set at the front of an open stage, or in the middle of a room. Bass wraps around the back, no way to stop it. Bafflestep compensation boosts the bass. For speakers backed up to a hard reflective wall, it makes the bass too heavy. Speakers against a wall perform in a "half-space". Your picture clearly shows your speakers backed up to a wall.
Amazing how obsessed the senior members on here are that every design be suitable for performing on stage.
Thank you, sir! I think I'm only like... around half an inch away from optimal as far as the crossover point and MTM sound lobe benefit goes!
Ah... then I did know something about it without knowing that I did. 🙂 I designed these for my smaller living/listening area, so I knew they'd be up against a wall and intentionally counted on getting some gain from that, so didn't want to make the lower frequencies too high. It actually works very well! FYI, my room isn't treated at all... but I'll get some in-room measurements, too 🙂
I doubt it. What is your XO? To acheive optimal spacing in an MTM the centre-to-centre of the 2 midbasses need to be within a quarter wavelength at the XO. Pretty much impossible to achieve with traditional tweeters. But certainly doable with a WAW.
I see other criteria mentioned but they are compromises.
dave
According to D'Appolito (in Ray Alden's Speaker Building 201), "in order for the 3/2 [MTM] geometry to work properly, the distance between the centers of the adjacent drivers should be kept close to one wavelength of the crossover's frequency."
My crossover is just over 2,000 hz, and that means from center of woofer to center of tweeter, it should be about 6.75 inches.
So I'm pretty close to that -- but if there are other findings, I'd love to learn.
Jess
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Pretty much.
But show admiration as well.
Since the truncated peerless frames and truncated Dayton plates.
Was of interest for center to center.
And keep moving down the line to 4" then 3"
and abandoned D'Appolito all together.
For Diy and personal enjoyment
Very nice build.
Far as marketing and asking price.
Dont see a DIY speaker selling for that much.
Finish quality be drastically different.
And numerous competition offer full 5.1 systems
for that price. And well established brand names.
It is a pretty tough market
But show admiration as well.
Since the truncated peerless frames and truncated Dayton plates.
Was of interest for center to center.
And keep moving down the line to 4" then 3"
and abandoned D'Appolito all together.
For Diy and personal enjoyment
Very nice build.
Far as marketing and asking price.
Dont see a DIY speaker selling for that much.
Finish quality be drastically different.
And numerous competition offer full 5.1 systems
for that price. And well established brand names.
It is a pretty tough market
You placed the mid dip very well in the measured FR. That gives you a more natural off axis sound to the ear and allows you to adjust the sweet spot by toeing speakers in or out.
Old and out of date. And one of thoaw, e’ll compromise on this number.
Remeber, every loudspeaker is a set of compromises.
For that frequency the ideal goal would be 1.7” centre-to-centre.
As i said, you will see other metrics used since this is not acheivable.
dave
This is your first build? ...wish my first build was this good! From the designing of the crossover, up thru the cosmetics, good job, you should be proud. My one and only concern is indeed that 2.5 ohm value...perhaps you should pop a two-ohm series power resistor at the back. By forcing your amp to see that kinda load is "playing with fire", while still working fine now, that may change in due time....consider it insurance.
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Rick...
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Rick...
You can see the downward trend, between 100Hz and 800Hz, with the, in-room, measured response posted. This is the baffle step losses I'm talking about.
No one said the design was going to need 6dB worth of compensation but 2-3dB? Sure.
You still get some bafflestep losses with speakers even positioned like that. They need to be flush mounted into a wall, or in a corner, to get none.
Hey SE, if you have Dave ragging on you, you know you're pretty close. Most of us don't get to this stage.