I'm after recommendations for HF drivers. This is for low power, off grid use, just for me, for fairly close listening (i.e. not for gigs).
System will be run off battery + chip amps, X-over will hybrid active and passive (miniDSP) - so I can apply EQ pretty easily. Most of my listening will be < 1 watt.
EDIT> the intention is to keep the electronics simple: 1 miniDSP, 2 amps. My default would be to have the LF/mid crossover active, and the mid/HF crossover passive <EDIT
My test rig has:
2x15"< 300Hz (12dB crossover)
6" mid on fairly big 2" horn 300Hz-1kHz (no crossover)
Dayton D250P-8 on fairly big expo horn >1kHz (12dB passive crossover)
...and I rather like it. I'm interested in trying something similar-but-better for the HF
EDIT> Picture of test rig added. I listen to the test rig very close, about 1m. It sounded better after I recessed the LF box by about 15cm relative to the horn mouths, but I have the mid & LF mouths on the same plane (despite the mid horn being longer).
The intent for the final build is to soffit mount. When I do that I could physically recess the LF component by slot mounting the woofers, or I could use digital delay. <EDIT
Smooth is good (hence interested in polyimide or similar). Reasonably priced is good.
It doesn't have to go all the way to 20kHz, or be super efficient (the Dayton unit is only 104dB).
My default would be the B&C DE250 or DE500 because Dr Geddes regularly used them as low as 1kHz.
...but I was considering the newer style annular diaphragm drivers,e.g.
Eminence N151M-8 because:
a) Patrick Bateman liked it and tested his with a 600Hz crossover - "I don't think it will have any issue doing 1khz on a decently large waveguide."
b) it measures well: https://audioxpress.com/article/test-bench-eminence-n151m-8-1-compression-driver
c) the annular claim of having a better / cleaner acoustic path is intriguing
Secondary query: assuming low power and a horn that supports a low cutoff, what drivers are NOT usable to 1kHz?
e.g. the cheap driver I'm using has a 44mm voice coil, power rating of 60watts and it works OK with a 1kHz cross.
--> Would any driver with 44mm voice coil and 60watts rating be just as happy at 1kHz?
--> The Eminence N151M-8 has a 38mm voice coil, smaller diaphragm, and is rated for 45watts but (according to PB) is still fine at 1kHz ...and PB kinda thrashes his gear. So that makes me wonder if any driver with a 38mm or greater voice coil would be OK.
System will be run off battery + chip amps, X-over will hybrid active and passive (miniDSP) - so I can apply EQ pretty easily. Most of my listening will be < 1 watt.
EDIT> the intention is to keep the electronics simple: 1 miniDSP, 2 amps. My default would be to have the LF/mid crossover active, and the mid/HF crossover passive <EDIT
My test rig has:
2x15"< 300Hz (12dB crossover)
6" mid on fairly big 2" horn 300Hz-1kHz (no crossover)
Dayton D250P-8 on fairly big expo horn >1kHz (12dB passive crossover)
...and I rather like it. I'm interested in trying something similar-but-better for the HF
EDIT> Picture of test rig added. I listen to the test rig very close, about 1m. It sounded better after I recessed the LF box by about 15cm relative to the horn mouths, but I have the mid & LF mouths on the same plane (despite the mid horn being longer).
The intent for the final build is to soffit mount. When I do that I could physically recess the LF component by slot mounting the woofers, or I could use digital delay. <EDIT
Smooth is good (hence interested in polyimide or similar). Reasonably priced is good.
It doesn't have to go all the way to 20kHz, or be super efficient (the Dayton unit is only 104dB).
My default would be the B&C DE250 or DE500 because Dr Geddes regularly used them as low as 1kHz.
...but I was considering the newer style annular diaphragm drivers,e.g.
Eminence N151M-8 because:
a) Patrick Bateman liked it and tested his with a 600Hz crossover - "I don't think it will have any issue doing 1khz on a decently large waveguide."
b) it measures well: https://audioxpress.com/article/test-bench-eminence-n151m-8-1-compression-driver
c) the annular claim of having a better / cleaner acoustic path is intriguing
Secondary query: assuming low power and a horn that supports a low cutoff, what drivers are NOT usable to 1kHz?
e.g. the cheap driver I'm using has a 44mm voice coil, power rating of 60watts and it works OK with a 1kHz cross.
--> Would any driver with 44mm voice coil and 60watts rating be just as happy at 1kHz?
--> The Eminence N151M-8 has a 38mm voice coil, smaller diaphragm, and is rated for 45watts but (according to PB) is still fine at 1kHz ...and PB kinda thrashes his gear. So that makes me wonder if any driver with a 38mm or greater voice coil would be OK.
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Hi,
for low power use why not, but there is limit for any driver in any application so I guess you'll just have to find out. To play safe you could buy what others have found out to work, as you wrote.
If you want better sound have you looked into swapping the horn? I remember Geddes saying there is more audible difference between waveguides than between drivers, don't remember/know the context though. But as it is low power use I would guess any driver is fine while most of the sound is in the waveguide (and system design overall).
for low power use why not, but there is limit for any driver in any application so I guess you'll just have to find out. To play safe you could buy what others have found out to work, as you wrote.
If you want better sound have you looked into swapping the horn? I remember Geddes saying there is more audible difference between waveguides than between drivers, don't remember/know the context though. But as it is low power use I would guess any driver is fine while most of the sound is in the waveguide (and system design overall).
Another cost effective 1" driver is the Selenium D220Ti. In my opinion, you still need to look at least at the resonant frequency (fs) of the driver, however small the power would be, as that is a physical aspect of sound reproduction.
I did not really like the DE500 much, but it could be that the pair I own is not in perfect shape. I tend to prefer plastic diaphragms or Ti with mylar surround. All Ti membranes usually sound slightly harsh in the high end to my ear at close distance and low power. But that might be just me and the drivers I had. I would say almost any 1" CD could do 1 kHz at low volumes. Some suggestions are here: https://www.diyaudio.com/community/...on-driver-may-2020-suggestions-please.353564/
I have a few to play with, and am not adverse to making them.
To some degree, I'd be doing both (at a minimum): the Dayton unit is a screw-on, with an adapter between it and the horn I'm using. Switching to the exact same driver, in bolt-on form, would improve the horn throat 🙂
"I remember Geddes saying there is more audible difference between waveguides than between drivers, don't remember/know the context though."
The context was pretty much all the time. His mantra was that any decent driver, was about as good as any other... but then he did swap his personal units from DE250 to DE500.
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I think I agree on not liking Ti membranes, but this is just me as a hobbyist with
a) small sample size
b) poor control when doing comparisons
I do sweeps increasing the voltage level looking for a rise in THD to determine how low I can cross a compression driver (E.G this type of measurement). Unfortunately the voice coil mag N151M-8 THD plot is cut off at 2kHz before the rising distortion so there is no indication on how low would be comfortable. I'm also planning on using this driver but for a >4kHz application due to its high efficency, smooth response and lack of resonances. Also not a fan of pure Ti drivers they tend to have high Q resonances in the 10 - 20kHz range. I'm using a P-Audio BM-D466 down to 1.27kHz with a 4th order electrical crossover but that looks to be the limit according to my THD measurements.
Seems valid, i.e. the rising THD in that plot <500Hz is informative.
...but to me it looks like that frequency (at which THD rises) is independent of voltage level: 1watt or 20watts, you'd still want to X-over at about 500Hz.
I posted some measurements of the 18Sound NSD1095N vs B&C DE250 on the 2nd page of the thread here: https://www.diyaudio.com/community/threads/18sound-nsd1095n-as-good-as-it-gets.381895/
The NSD is, IMO, a step up from the DE250, but of course they're also in a different price bracket.
IMO, drivers which could be used in many projects (or one long-standing one) are worth spending the cash on, as you'll reap the benefits for years to come.
Chris
The NSD is, IMO, a step up from the DE250, but of course they're also in a different price bracket.
IMO, drivers which could be used in many projects (or one long-standing one) are worth spending the cash on, as you'll reap the benefits for years to come.
Chris
That may not be the driver's limit - the horn is only 15cm long, and the data sheet says it loads to 1200Hz.
https://ampslab.com/blog/2016/10/29/dayton-audio-d250p-review/
This review/build is using the same horn as my test rig, which is 5cm longer, with a claimed 800Hz limit. Mike / Mr Ampslab used a 950Hz crossover.
If you look at 300Hz however, you can see that your top 2 sweeps show a much bigger step up in distortion than the relatively consistent increments between the lower driver levels.
That tells you that, on this horn, you don't want to cross as low as 300Hz. Now, that may be precluded by other factors anyway (I don't know that particular horn), but the point is it's that divergence between the distortion curves that you're looking for, as well as just the general increase as frequency decreases.
You can take these down to 500Hz if you use them appropriately or use them at low levels. A waveguide will be large at that frequency.
http://p-audio.co.uk/pdf/PH_4220.pdf claims Fc = 400Hz ... what the actual acoustic impedance is at 1kHz though I don't know.
Horn loading doesn't really mean the horn giving something for the driver to push against.
In any case, some horns can readily be used below where they load and some are problematic.
In any case, some horns can readily be used below where they load and some are problematic.
It doesn't? What does horn loading mean, then? Is it not to do with the acoustic impedance transform?
For infinite length exponential horns Fc is the frequency below which sound propagation no longer occurs so has a strict definition. For real horns there is no strict definition but its often taken as the point where the real part of acoustic impedance = 0.2.
^^ Yes. The significant element constraining the diaphragm will be the compression ratio, and that doesn't change between horns.
How about radiation efficiency?
I mean loading in the normal sense, just getting down to details.. did you mean something in particular?
I felt this was relevant a few posts back because of the THD measurement.
I mean loading in the normal sense, just getting down to details.. did you mean something in particular?
I felt this was relevant a few posts back because of the THD measurement.
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