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Multi-Way Conventional loudspeakers with crossovers

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Old 6th June 2013, 05:38 AM   #1
macsaif is offline macsaif  Slovakia
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Default which WG for DE250/8ps21

Hello,

which waveguide you recommend for the DE250 / 8ps21 combo? Is it possible to use bigger (10-12 inch) waveguide in case of crossing with 8 inch woofer?
The baffle width of the loudspeaker will be 35-38cm.
I was considering XT120, XT1086, Seos8 - 10 - 12, Pyle PH612.
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Old 6th June 2013, 04:00 PM   #2
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The Pyle is a screw-on type (and the adapters don't work that well), so probably not that one.
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Old 6th June 2013, 07:57 PM   #3
ANFR is offline ANFR  Denmark
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Hello Macsaif,
I have the combo of the DE250 and 8PS21 as top in a 3-way and I am happy with it.
I use the RCF H100 horn/waveguide. I cross it around 1600-1700 Hz. I prefer a not too narrow projection. I prefer it over the combo of the XT1086 with the BC DE25 I also have (with 18S 6ND430 as mid) even it is also good.
Best regards,
Anders
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Old 6th June 2013, 10:06 PM   #4
macsaif is offline macsaif  Slovakia
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Do you have active or passive crossover? Do you use it as PA or hifi?
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Old 8th June 2013, 06:31 AM   #5
ANFR is offline ANFR  Denmark
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I use it for hifi. I cross passive between the DE250 and the 8PS21. As a 3-way I also include a HP 1st order and resonance RLC for the low end of the 8PS21.
The (sub-)bas (BC 18PS100) is LP'ed and equalized by a MINIDSP.
The combo provides very clean sound with good resolution and transient qualities.
My top cabinet have a front baffle of 38cm (W) and 53cm (H). The 8PS21 is in a small sealed enclosure of 5-6 l (from memory). The width allows the baffle step loss to be part of the HP for the 8PS21 and supports the low range of the H100 horn..
I started out with the 18S 8NMB420, but it was not clean enough in the midrange.
I have 2 other 3-ways to compare to in addition to the one mentioned above (DE25/XT1086+18S 6ND430+ 15"JBL):
Rebuild in AR11 cab 42 l sealed: SB Acoustics SB29RDCN+SB Acoustics 5"+ Scanspeak 30W/4558T00, all passive.
In 110 l saled cab: 10913+Scanspeak 15W/8531K01+ SB34 12" woofer, all passive.
All provides clean and pleasant sound, but the DE250+8PS21+18PS100 is my preference and can play good at realistic levels.
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Old 8th June 2013, 09:21 PM   #6
macsaif is offline macsaif  Slovakia
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It sounds good.
Originally I have planned to use miniDSP to each loudspeaker and use 3 power amplifiers however I am thinking to do it as you that Mid/High - passive and use active crossover only for Bass/mid. I need to do some corrections on the bass (baffle step, 20Hz HP filter, phase ....). In that case I need only 2 power amplifiers/loudspeaker.

1.Which solution should be better
a. 2xminiDSP + 2x3 power amp
b. 1xminidsp bass/mid - 2x2 power amplifiers + passive mid/treb.
c. anal.active crossover -2x2 power amplifiers + passive mid/treb.
2. What kind of power amp.you use (how many W?)
3. Dont you have a problem with higher noise level of the miniDSP? Somebody told me that it has higher noise level than for.ex. standard CD or DAC output.
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Old 9th June 2013, 02:15 AM   #7
Jay1111 is offline Jay1111  United States
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You really wont have to cross that low to an 8" using a waveguide. Something like this will easily work

EOS-8 DIY Sound Group
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Old 9th June 2013, 02:37 AM   #8
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Better is subjective and also depends on your design goals.
1.a/b/c Yes all could work fine and have a very good end result. Example I'm testing designing a system that originally miniDSP with a near perfect passive cross between mid/tweet. This has been tested and yet have also gone straight without passive, just for kicks, how did it sound very good, but the passive was better (phase perfect +/-1.3oct). rePhase would negate the difference if implemented.

2. size them right, your choice of type/application. < example, design power 100w. Active woofer crossed @350 to a passive x mid/tweet. Half power (50w) would be require for the woofer and half (50w) mid/tweet. 15-20w amps are all that are necessary for most tweeters. If active protect that tweeter with a high quality metal foil cap, 100uF should work.
Now who was it that posted a table on power distribution/freq the other day... hmmm

3. if >105dB isn't quiet enough we wouldn't be talking $100-300 ea
Have read a few people mention they can hear the noise floor and they all appear to have very high efficiency speakers on top dollar systems.
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Old 9th June 2013, 07:43 PM   #9
ANFR is offline ANFR  Denmark
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Greebster I think you are very rigth about realizing one's design goals.

In my case I wanted initially to make it all passive (3-way), but I chose to buy and use a MiniDSP (the small 4 channel) and run active bas with passive top and experiment with it of the following reasons:
- A delay could be introduced on the top compensating the delay of the bass (bass reflex).
- The sensitivity match is more flexible and LP modifications straight forward.
- Equalization of the bass became possible.
Eventually I have kept the HP of the mid in the passive cross over combined with the impedance resonance attenuation RLC. I might still try an all passive alternative also.

With respect to crossover frequencies I made the following assessments:
- The BC18PS100 seems not good very high, I have ended up using 125 Hz in the MiniDSP.
- The Mid-Tweeter point of 1600-1700 Hz was chosen as the DE250 sound good that low and I wanted the 8PS21 to start the crossover deca (LP) that low that the resoncance peak and the breakup didn't came to close into the overlapping frequency range. Also the increased directivity (more narrow) range are kept more away from the overlapping range.
I believe the DE250 (with the RCF H100) matches good with respect to radiation pattern at this crossover point.

I have no practical problems with the noise from the MiniDSP.

Going passive on the top I have experienced as with other crossovers, that the quality of the caps is significant. I use Jantzen Super Z for tweeter and for the mid I have the AmpOhm's to be very good and less expensive than the Super Z's. The DE250 sounds absolutely great with the Super Z's. But it all up to taste and economy.

One reason for me not to go active for the top is that the more easy it is to adjust and change the more you have to do on validating and test if you change amplifiers and pre-amps. Having the top made passive it just Works.

Good luck with your project Macsaif.
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Old 10th June 2013, 01:31 AM   #10
IG81 is offline IG81  Canada
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In itself, a larger waveguide is a good thing IMO, but keeping a short distance between driver centers is also a good thing. Another aspect of the balancing act that is speaker building.

IG
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