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Old 2nd December 2001, 08:21 PM   #1
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Here's the deal: i'm building a 3 way system- to be split via an active crossover. Current x-over points are: 500hz and 3k to 5khz. My goal is a balance of quality of sound (freq resp., phase, imaging, etc) and dynamics.

I'm pretty sure on the lower point (500hz), based on my drivers (see below); but i'm unsure of the upper x-over point. Anywhere from 3k-5k - it's well above the Fs of the tweeter.

I already have my amp to drive the woofers (Acurus), and the Mids (Sumo), but i do not have the amp for the highs yet.

This is what i asked in the 'loudspeaker' forum:
So i'm wondering if anyone could point me to a function/equation that would allow me to calculate my power req's of my upper end amp based on the x-over point.
-i asked this to figure out what power range of amps i should be considering.


If you have any other input on the 3k - 5k x-over points, please chime in.


i this forum i ask you this: tell me why i should consider tubes for the High Freq amp?

i am considering getting 4 (not 2) of the vifa tweeters mentioned below and running them dipolar... any input on that? (and would the drop/gain in impedence, from 6 ohms for one driver, to 3 or 12 ohms for a pair per side, be of any benefit in getting more sound out of your recommended tube amp?)

components:

X-Over: 3 way active w/ low pass, band pass, highpass x-over points. Each portion will have a level control.

LF driver: 2 x A/D/S 312rs.2 12" dual 4 ohm VC's sens: 92db; nom. power handling: 600w rms

Mid Driver: A pair of Gallo Micros, [they claim to work from 90hz and up... but i was unsatified with them as rear/surround speakers] so i'm using them as mids here. 100 watts power handling above 100hz, sens: 92db

HF Driver: Vifa D27TG-05-06. 92db sens, and 100 watts above 2.5khz

LF Amp: Acurus A200x3. 200watts into 8 ohms (315watts into 8 per Audio Mag [r.i.p.]) -- yes, that leaves one ch. to spare (hehe) maybe an active Adire tempest subwoofer?

Mid Amp: Sumo Polaris II. 100+ watts into 8 ohms

HF Amp: to be determined.

in the meantime, the A/D/S and Micros run as a passive x-over'd bi amped 2 way pair (at 500hz)
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Old 2nd December 2001, 10:53 PM   #2
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The hands-down best place for tubes is the midrange. The upper frequencies are more of a toss-up as to whether to go tubes or solid state. It will depend on the circuit. Sometimes solid state is better--sometimes tubes.

Grey
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Old 3rd December 2001, 04:07 AM   #3
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Default High Hz amp

Personally I like the way tubes distort at the upper levels better than the SS. This is not always the case and often depends on the equipment involved but I find the highs generated by SS to be piercing. Sustained highs can get down right uncomfotable. This does not happen to me with tubes. Some people call this the warmth of tubes but I personally believe that tubes distort in such a way that it is natural sounding and therefore not bothersome. I just bought an active crossover and I am planning on using SS for the woofers and SE tube for the mids and highs. I will still use passive crossover parts for the mid/tweeter. If you do decide on tubes for your highs wire the tweets in series and double the impedance since tubes like higher impedance than SS. Higher impedance cables might be a help on the tube amp as well. Something you might try down the road. Single ended tube amps with the right speakers create the best presence and sound stage I have ever heard. And I listen to a lot of stuff. If you do get SE tube try running both the mids and highs off it sometime just for grins.
David Thatcher
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Old 3rd December 2001, 04:39 AM   #4
paulb is offline paulb  Canada
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http://sound.westhost.com/bi-amp.htm
Rod has a good article on biamping & triamping, and there's a table of % power vs. crossover frequency - I believe it says 10% above 5 kHz, 60% below 500 Hz.
My gut feel says that the best amp should go in the midrange. If I ever get my triamp system off the ground, the midrange will be an Aleph.
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Old 3rd December 2001, 03:17 PM   #5
walker is offline walker  Australia
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Hakalugi, something to contemplate, your low/mid crossover is in the middle of vocal and most instruments range. This is a personal opinion; I like to get full coverage of the 100-2kHz from one driver, not a difficult task,(I know that many instruments go below 100Hz). Less damage can be done by the crossover region. There aren't many woofers that handle this area well even if they can emit it. This will make a considerable change to the power handling of your mids.

I have to say that I'm not familliar with your mids.

Seeing that you are going active you will have the ability to try a number of crossover frequencies.

I would like to hear others thoughts on this,
Regards WALKER

[Edited by walker on 12-03-2001 at 09:26 AM]
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Old 3rd December 2001, 05:03 PM   #6
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Default Re: High Hz amp

Quote:
Originally posted by Thatch_Ear
... I just bought an active crossover and I am planning on using SS for the woofers and SE tube for the mids and highs. I will still use passive crossover parts for the mid/tweeter. If you do decide on tubes for your highs wire the tweets in series and double the impedance since tubes like higher impedance than SS. ....
David Thatcher
David, thanks for the feedback.

Quote:
Originally posted by paulb
http://sound.westhost.com/bi-amp.htm
Rod has a good article on biamping & triamping, and there's a table of % power vs. crossover frequency - I believe it says 10% above 5 kHz, 60% below 500 Hz.
My gut feel says that the best amp should go in the midrange. If I ever get my triamp system off the ground, the midrange will be an Aleph.
great link, thanks. table is just what i needed. (and i'm looking at a Passlabs, too


Quote:
Originally posted by walker
Hakalugi, something to contemplate, your low/mid crossover is in the middle of vocal and most instruments range. This is a personal opinion; I like to get full coverage of the 100-2kHz from one driver, not a difficult task,(I know that many instruments go below 100Hz). Less damage can be done by the crossover region. There aren't many woofers that handle this area well even if they can emit it. This will make a considerable change to the power handling of your mids.

I have to say that I'm not familliar with your mids.

Seeing that you are going active you will have the ability to try a number of crossover frequencies.

I would like to hear others thoughts on this,
Regards WALKER

[Edited by walker on 12-03-2001 at 09:26 AM]
technically, my x-over point is 382hz (the 'start point' of the HighPass portion of the mid/bandpass is 500hz) but i see what you mean.

I'm using the Gallo Micros because they're already in my possession and pretty broad banded. But i may find myself switching to a Jordan driver (jx 125/ jx 150 to handle the 100hz to 3-5khz range) if i find the 382hz x-over objectionable.

I was thinking of the ~400hz x-over point b/c (apart from power per hz consideration) because the Gallow Micros have a peak around 200hz that i don't care for... oh, for more info, go here: http://www.roundsound.com/home.htm

anyways, the active x-over has not yet been purchased... i think i'll just finish this as a 3 way with 1st order crosses, LP starting at 284hz; band pass: 500hz and 3200hz; HP starting at 5600hz. and see how it sounds. all off the Acurus. --so that i can better compare it against the 'benefits' of the active system when it's done.


-again, thanks all for the feedback.

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Old 3rd December 2001, 09:42 PM   #7
walker is offline walker  Australia
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Hakalugi, I currently crossover at 200Hz because my mid has problems below that. The speaker system that Iím building now will crossover somewhere around 100Hz, (I hope) only time will tell. If your mids have a peak at 200Hz then you could set your bass crossover at 180Hz and the mid at 220Hz or something like that. Do you follow? The 200Hz peak will fill in the mismatch.

Iíve found it hard to guess crossover points, best to play with them to get the best result. This is one of the advantages of active crossovers. If you use passive crossovers please mount them outside the enclosure, it makes adjustments much easier and the crossovers are less susceptible to microphonics.

Regards WALKER
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Old 3rd December 2001, 10:03 PM   #8
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Default :)

thanks again walker- i was thinking of such an arrangement, too. i bought my coils/caps in multiples so that i could parallel and series them to made my x-over ~190 instead of 382 for just that reason... i'll post any findings.

cheers.
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