Are these the correct parameters to use for the Pioneer B20FU20-51FW? http://www.partsexpress.com/pdf/290-045.pdf Or the published parameters from Pioneer?
Hard to say since the individual components are always being 'improved' by order of the 'bean counters' and retailers rarely bother to update their measurements like Eminence, JBL, etc., do. I mean I have measured specs from 10 yrs ago and they're not even close to the PE's, dictating a much smaller cab, so fortunately can be easily made to work with later driver's alignments, hence the specs that yields the largest cab are the ones I recommend since it's easier to shrink a cab than 'stretch' it. 😉
GM
GM
Guess 'plenty big' is in the 'eye of the beholder', my fave B20 cab was a ~10.15 ft^3/30 Hz ML-horn........ 😉
GM
GM
re:big - did it play clean? - - I've never heard B20 "clean" but only had it in modest size BR and pipe - - show me some two tone modulation tests - lol
In the intended app, yes, but if you're asking if it defied the laws of physics or had the damping of a BP, of course not.
GM
GM
I've used B20 in a little klam at high spl - are they popular on flat baffle from 250 or so upward with helper woofer? - that and network runs the cost up
The ML-horn started life as an OB with the B20's woofer variant filling the bottom end with a bit of added mass loading and a piezo horn nestled in the lee of the two in an absolute minimum driver spacing MTW. At apt./small room levels it was pretty impressive for the cost, but obviously there was only so much that could be done about the B20's basic mids/lower HF lack of high SQ resolution, so went for the low buck single driver in-room bass 'wow' factor plus piezo since it was for mostly '50s-60s DooWop, R&R, etc..
How'd it do in a Klam? I don't recall seeing any details/measurements of it.
GM
How'd it do in a Klam? I don't recall seeing any details/measurements of it.
GM
re:B20 in klam = same klam8 as this video loaded with Sammi - Sammi could take a bit more power - B20 sounded ok at 20-175 feet away - theres was about 10dB more noise available than what is in this video - I've measured these things
http://www.youtube.com/watch?v=znfE7hjQ40o
if one put B20 in a vented system it would blow the one out or modulate badly way before it ever reached these levels - although there's no low bass it sounds like theres some bass at high levels - klam small signal qtc could be set somewhere between 0.7 and maybe 1 - it'll change anyhow at large signal and voice-coil heating/
http://www.youtube.com/watch?v=znfE7hjQ40o
if one put B20 in a vented system it would blow the one out or modulate badly way before it ever reached these levels - although there's no low bass it sounds like theres some bass at high levels - klam small signal qtc could be set somewhere between 0.7 and maybe 1 - it'll change anyhow at large signal and voice-coil heating/
>>> And here's my 1m on axis in an OB
Thanks for the curves Nelson. Are you getting around 90db per watt? Just curious how OB might change efficiency. Output begins to drop at about 150hz.
I'd add a piezo around 10k and call it a day.
Godzilla
Thanks for the curves Nelson. Are you getting around 90db per watt? Just curious how OB might change efficiency. Output begins to drop at about 150hz.
I'd add a piezo around 10k and call it a day.
Godzilla
here's BU20 indoors ~ 10 ft on axis 1/6 octave in a Druid type pipe vs Eminence B102 - I'm struck by the 8dB difference at 55Hz - might pull one from a klam and do TS
An externally hosted image should be here but it was not working when we last tested it.
Nelson Pass said:
Hi Nelson:
Do you mind re-posting your TL design for these? I can't find it via search, and no harm having it available in more threads so others can find it anyway, eh?
I just got a screaming deal on a quad of these so....
freddi said:
Sounds really bad, but then neither YouTube nor my computer sound system are remotely HIFI.
Yeah, BP4 can really play loud over a narrow BW, so could be a viable option in a multi-way system.
Right, Mike Bates? trashed me when I mentioned this on one of his threads, but a 1.0 Qtc K-BP4 with multiple drivers to keep thermal power compression low and with the right specs could theoretically have several octaves of gain BW, but all things consider, a TH with a K slot mouth might be a better choice overall. If I'm ever again able to do building/testing, this is high on my audio curiosity projects list.
GM
Nelson Pass said:
Thanks! Interesting the difference between it and others published near-field? responses over the years.
GM
badman said:
I love Google 😀, the first link yielded plans, measurements: http://www.diyaudio.com/forums/showthread.php?s=&threadid=60632&perpage=25&pagenumber=3
GM
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