Worked up a pretty good looking crossover design this morning before the rest of the house was awake. LR4 @ 3.5 kHz. Total of 11 parts per side, three of them are just resistors. Problem with narrow width baffles is the very pronouced diffration hump above the BSL. That takes a series notch, then a few extra parts to suppress the aluminum cone's breakup. I have all the parts on hand so I might be voicing these by weekend's end.
Prototype xo's are together. Probably get to do some listening tomorrow. I just threw these xos together with what I had on hand, read: a bunch of Madisound buyout 10 uF mylars, two NPE caps, and two buyout 20 gauge steel laminate core inductors.
@PWRRYD said:
Prototype xo's are together. Probably get to do some listening tomorrow. I just threw these xos together with what I had on hand, read: a bunch of Madisound buyout 10 uF mylars, two NPE caps, and two buyout 20 gauge steel laminate core inductors.
Sounds like my kind of prototyping. I use a bunch of Audiophiler caps, though. Bought a shitload of them strictly for inexpensive builds and prototyping. My favorite stage of design work!
Today was "Christmas" decoration day. The MAC-4 woofer is a good sounding little woofer and a great driver for the price.
The Beston RT003C isn't a complete turd but is by far the limiting driver in this design. Its distortion mandates that it is crossed north of 3.5K. And even crossed that high its distortion is an order of magnitude higher than a dome tweeter costing 1/2 the price.
Yeah, that is pretty bad. I measured a Pyle automotive tweeter years ago that measured ruler flat from 3K but had similar distortion profile. In the garbage it went, live and learn.
HD is high compared to SOTA drivers, but when you look at it like the minimum requirement is -25dB, it is close to that. Did you take the HD after the xover was added? Don't forget that series resistance damps the HD according to the Purifi guy, and i needed a 15 ohm in series to pad it to match. This can help as well. Did you use a cap or treble only source track on it when you measured it? This driver really can't play low and drops like a rock below 3k. There could be several reasons why it looks the way it does when used raw.
Like I said before, it sounds different, but not bad. These little boogers render brushed cymbals much better than a lot of other tweeters have, IMO. Sometimes it is more than the lines on the paper.
It's one of the reasons I never posted the HD plots I took as it would deter builders from trying it. The same thing happened to the Dayton PT2 when Zaph gave it a horrible review. Truth was it wasn't a bad driver either, used in its optimal way.
To back up my observations and earlier comments regarding the Beston vs the MAC, here is the distortion measurement of the MAC-4 driver inbox, same mic distance, same drive level, etc. Raw driver measurements, no crossovers applied:
Yeah, there is a distortion blip around 2.2k but it doesn't stand out in any way. In my opinion this driver sounds WAY cleaner and more detailed through the midrange compared to the Dayton ND105-4 or the TCP115-4. The ND105 is harsh and the TCP115 is kind of dull.
Sorry, gona let my stupid out.. But I've never thought a whole bunch about this before..
That 3rd order peak looks identical to the cone breakup peak. If you squash the breakup does it also squash those 1/3 and 1/2 frequency peaks? Rendering it a non-issue if taken care of?
Not necessarily. 2kHz peak is there because of 6kHz breakup. output of the driver is boosted at 6kHz, so 3rd harmonic generated at 2kHz occurs at 6kHz, and is boosted. Filtering the input signal upstream does not change this, 3rd harmonic will still be boosted, the breakup and natural behaviour of the driver is still there.
Of course, reality is a bit more complex with passive components. Speakers are an electro-mechanical transducer, electricity turns to sound, just as sound turns to electricity, so resonant behaviour of the cone becomes a back EMF force on the voice coil. Depending on circuit topology, resonant modes can be damped somewhat. Digital filters don't provide this luxury unfortunately.
Ok I see.. I was thinking about it backwards. The 2khz frequency creates a 6khz resonance not the other way around. And the energy is being stored within the cone flexing so it minimally moves the coil compared to the output it is creating. You can only damp that coil movement with the circuit, so the damping is only so effective. Sorry to muddy up the discussion. Thank you, Carry on
If I'm understanding correctly, then no unfortunately. Because the issue is actually being created at 2khz. Even if 0 voltage is being given at 6khz. The distortion would only be 6db down, the same as the 2khz response being 6db down.
Like an annoying dog that howls when you sing. Only way to stop it is to stop singing (or stop playing 2khz in this case, then 6khz stops ringing). I edited my response above. I finally saw the light and just now getting over my mind being blown. Scraping the chunks back together.
OK - this finally clicked for me too. Really interesting stuff. I thought the 3rd order HD was a mechanical occurance of the cone but is both mechanical and electrical?
Comments
Micro-tower build . . .
The rate at which Craig can just whip threw projects is very impressive, and he is constant in action. Amazing.
I like to stay busy
Worked up a pretty good looking crossover design this morning before the rest of the house was awake. LR4 @ 3.5 kHz. Total of 11 parts per side, three of them are just resistors. Problem with narrow width baffles is the very pronouced diffration hump above the BSL. That takes a series notch, then a few extra parts to suppress the aluminum cone's breakup. I have all the parts on hand so I might be voicing these by weekend's end.
Looking forward to your impressions of our little driver.
Prototype xo's are together. Probably get to do some listening tomorrow. I just threw these xos together with what I had on hand, read: a bunch of Madisound buyout 10 uF mylars, two NPE caps, and two buyout 20 gauge steel laminate core inductors.
Sounds like my kind of prototyping. I use a bunch of Audiophiler caps, though. Bought a shitload of them strictly for inexpensive builds and prototyping. My favorite stage of design work!
Yep mine too!
I can get a pretty good idea how a driver sounds even using less than stellar xo parts.
Absolutely.
So the Beston was not good?
. . . And, WHICH Beston?
Today was "Christmas" decoration day. The MAC-4 woofer is a good sounding little woofer and a great driver for the price.
The Beston RT003C isn't a complete turd but is by far the limiting driver in this design. Its distortion mandates that it is crossed north of 3.5K. And even crossed that high its distortion is an order of magnitude higher than a dome tweeter costing 1/2 the price.
Thanks for the heads-up concerning the RT003C.
I don't mind it. It sounds 'different', but I would not call it bad.
InDIYana Event Website
I really like the round Beston in the Indium 7, but the high pass is at 5 kHz...
Sehlin Sound Solutions
Beston RT003C in box distortion measurement at 25 inch mic distance. SPL is accurate.
😳 that might be the shittiest Distortion graph I’ve ever seen so far.
Yeah, that is pretty bad. I measured a Pyle automotive tweeter years ago that measured ruler flat from 3K but had similar distortion profile. In the garbage it went, live and learn.
HD is high compared to SOTA drivers, but when you look at it like the minimum requirement is -25dB, it is close to that. Did you take the HD after the xover was added? Don't forget that series resistance damps the HD according to the Purifi guy, and i needed a 15 ohm in series to pad it to match. This can help as well. Did you use a cap or treble only source track on it when you measured it? This driver really can't play low and drops like a rock below 3k. There could be several reasons why it looks the way it does when used raw.
Like I said before, it sounds different, but not bad. These little boogers render brushed cymbals much better than a lot of other tweeters have, IMO. Sometimes it is more than the lines on the paper.
It's one of the reasons I never posted the HD plots I took as it would deter builders from trying it. The same thing happened to the Dayton PT2 when Zaph gave it a horrible review. Truth was it wasn't a bad driver either, used in its optimal way.
InDIYana Event Website
To back up my observations and earlier comments regarding the Beston vs the MAC, here is the distortion measurement of the MAC-4 driver inbox, same mic distance, same drive level, etc. Raw driver measurements, no crossovers applied:
Yeah, there is a distortion blip around 2.2k but it doesn't stand out in any way. In my opinion this driver sounds WAY cleaner and more detailed through the midrange compared to the Dayton ND105-4 or the TCP115-4. The ND105 is harsh and the TCP115 is kind of dull.
Sorry didn’t mean to talk bad but I figured a $35 tweeter would measure better than that. I measured the MAC-04 awhile back in IEC. My results
Sorry, gona let my stupid out.. But I've never thought a whole bunch about this before..
That 3rd order peak looks identical to the cone breakup peak. If you squash the breakup does it also squash those 1/3 and 1/2 frequency peaks? Rendering it a non-issue if taken care of?
Not necessarily. 2kHz peak is there because of 6kHz breakup. output of the driver is boosted at 6kHz, so 3rd harmonic generated at 2kHz occurs at 6kHz, and is boosted. Filtering the input signal upstream does not change this, 3rd harmonic will still be boosted, the breakup and natural behaviour of the driver is still there.
Of course, reality is a bit more complex with passive components. Speakers are an electro-mechanical transducer, electricity turns to sound, just as sound turns to electricity, so resonant behaviour of the cone becomes a back EMF force on the voice coil. Depending on circuit topology, resonant modes can be damped somewhat. Digital filters don't provide this luxury unfortunately.
What if it was crossed 6db down at 2KHz using an electronic/DSP filter/XO?
Ok I see.. I was thinking about it backwards. The 2khz frequency creates a 6khz resonance not the other way around. And the energy is being stored within the cone flexing so it minimally moves the coil compared to the output it is creating. You can only damp that coil movement with the circuit, so the damping is only so effective. Sorry to muddy up the discussion. Thank you, Carry on
The driver would receive 6dB less signal at 2Khz...
. . . And would the 6KHz and 2KHz HD also drop to/near non-existence?
If I'm understanding correctly, then no unfortunately. Because the issue is actually being created at 2khz. Even if 0 voltage is being given at 6khz. The distortion would only be 6db down, the same as the 2khz response being 6db down.
Like an annoying dog that howls when you sing. Only way to stop it is to stop singing (or stop playing 2khz in this case, then 6khz stops ringing). I edited my response above. I finally saw the light and just now getting over my mind being blown. Scraping the chunks back together.
OK - this finally clicked for me too. Really interesting stuff. I thought the 3rd order HD was a mechanical occurance of the cone but is both mechanical and electrical?