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Active Bi-Amping/Tri-Amping FAQ


Chris A

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And then start all over again when the design proves unlistenable.

Just because you don't know how to get something right on the first try doesn't mean others can't :D

Btw, those Hypex amps are crazy awesome.

From all indications and the tech. papers I read from the designer, I would agree.

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  • 4 months later...

Iv been running my man cave system for five years, just went active last Thursday and had a visit from a guy today, behind my house, four doors down.

He did did not mind the tunes, it was the Bass.

Yes active is the way, for the rest of my days, well worth the money.

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  • 11 months later...

A big thanks here to Chris A. and participants in this thread for expending the funds, energy, and time to document and explain how to get around the issue of time delay.

 

Interestingly, I was reading Dr. Klipschs' Dope from Hope Volume 13, No. 3, in answering a question (2) regarding phase shift in amplifiers said "In 1972 I presented a paper "Delay Effects in Loudspeakers". Time Delay and "Phase" are one and the same. You can move your head a foot and change the "phase" of a 6500 HZ tone a matter of 2160 degrees. The delay is only 0.0009 second. The fact that speaker displacements in a 2-way and 3-way systems of up to 2 feet are undetected should indicate in insignificance of the delay effect as long as it is within the 2 foot limit. As a matter of fact our experiments here indicate the limits may be of the order of 4 feet or nearly 0.004 second."

 

Ok, so it seems he was saying that as long as your woofer, mid, and tweeters are within 2-4 feet of each other you're good to go. Or am I reading that completely wrong?

 

A couple of questions for the active crossover pros:

 

1) Do all of you have professional equipment or are you running a rack full of balanced to unbalanced converters?

 

2) Most of the nice system processors have software that runs on a PC. They (all) fail to mention what operating system is required. I already know the answer is Windows. Here is the question, has anyone come across processor software that runs in a browser?

 

Once again, thanks to all and have a great weekend!

-bb

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It's been my experience that time alignment of drivers needs to be within about 1/10th of a wavelength at the center crossover frequency in order to not be clearly audible. 

 

If you dial in a sine wave at the center frequency of a midrange-tweeter crossover and simply dial one channel delay off by a few microseconds, it will drive you out of the room listening to it.  It's the same story for the bass bin-midrange, except that the delays are about 10x longer to achieve the same effect--proportional to 1/10 wavelength at both crossover points. 

 

Also, it is audible to hear the 360 degree (one wavelength) delays of drivers, assuming that you have inadvertently inserted too much or too little delay - you can hear it on the transients - drums, percussion, etc.  Once you correct all delays/phase issues at the crossover points with the Jubs, they sound very "crisp" on transients.  It also shows up clearly on the measured impulse/ETC plots.

 

All my equipment has XLR balanced connectors from the Preamp-downstream, except for a First Watt F3 amplifier driving the TAD TD-4002 compression drivers, which only comes in RCA (unbalanced) connectors.  There I use an XLR-to-RCA connection, which works fine.

 

I've not seen a "browser app" for my active crossovers, but in general, I don't use the PC_based software-except for the two XTi-1000 amps pushing my SPUD subwoofer drivers, which actually require you to use System Architect from HK (parent of Crown).  I fat finger in the settings--it works very well, indeed and is easy to change on the fly without having to hook up the crossovers to the laptop via USB or ethernet connections.

 

Chris

Edited by Chris A
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Thanks for the reply Chris and I agree it is audible when you hit alignment, as the sound image comes into focus. I guess PWK's opinion was from the perspective of the guy that had to mount stuff into a box, make it look good, and be able to sell them. I seem to have achieved basic alignment manually with a frankenwall setup and a laser level.

 

The EV DC One appears to function fully from the front panel so I guess that's it for me, as you can see from my avatar, I just can't run windows here. Unfortunately I'm maxed out on AC connectivity so no rack-o-converters either. All my tube amps have consumer connectors.

 

Do you have any thoughts regarding alignment in the vertical plane as I might play with a "flying" tweeter. I'm guessing if you center the dispersion angle of each horn at face level, its going to sound pretty good.

 

BTW, thank you for the Missing Octave thread. Awesome stuff there and a good six months of playing with my flacs!

-bb

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Do you have any thoughts regarding alignment in the vertical plane as I might play with a "flying" tweeter. I'm guessing if you center the dispersion angle of each horn at face level, its going to sound pretty good.

 

I assume that you're talking about positioning a tweeter in the mouth of a midrange or bass-midrange horn.  It will work very well if the tweeter's shape isn't too reflective of acoustic energy from the rear (i.e., it isn't really big) and you delay the tweeter channel to align with the midrange.

 

If you are talking about "flying" a tweeter above or below the midrange, then the same deal applies: time alignment is key.  If you're crossing above 2 kHz or so, a baffle really isn't required for the tweeter.

 

in fact, the K77 tweeters mounted in the Heritage Klipsch speakers really need to be moved to the back of the cabinet on top of the speaker so that they are not looking through the 3/4 inch (19 mm) thickness of the front baffle and are aligned in time with the midrange driver mounting surface.  It makes a huge difference in the soundstage once you do this with any of the Klipsch Heritage models (but covering the hole in the Heresy to make it airtight again).  The K-77 tweeters also work a little better mounted vertically--as detailed in the old EV literature. 

 

From time to time, I plan on updating the "Missing Octave" thread based on things that I learn.  Right now, I'm still remastering--actually "unmastering"-- my flac music library: it has been a pleasure to listen to all this music that I've listened to for a long, long time with a new and much better/natural sounding set of tracks.  Highly recommended.  They beat my multichannel versions of the same tracks now, since the multichannel tracks also have the same issues - poor mastering.

 

Chris

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Yeah, I'm experimenting with this stuff in a manual sort of way by physically aligning components by calibrated eyeball and help from a laser level.

 

Cornwalls on their side, with a 2" Eminence mounted to a Selenium bi-radial sitting on top, centered. The tweeter is a B&C DEC120 with that crazy FaitalPRO elliptical (it's the 80x70) on a speaker stand, a piece of 2x4 and lots of speaker gasket tape. I use the Cornwall crossover and the unbridged woofer posts to connect a 100W class D.

 

All of you guys with the nice custom crossovers please cover your eyes because you're not going to like this part: I was anxious to hear the new stuff, and not having the ability to build a crossover,  I bought a Dayton 800/5.2K 3-way. So the new top end is connected to that and my 6 watt tube amp. Ghetto setup for sure, but hey - I'm single. So yes, the flying tweeter is up in the air to clear the mid horn which, when physically aligned with the woofer hangs off the front of the Cornwall by quite a bit. I get to play with toe in for each speaker. I have a bag of Mills 1 percent resistors to pad the mid and tweet down to the woofer sensitivity, but to be honest these horns sound incredible at their stock output levels (mid is 110db, tweet 106), seems to smooth out some of the direct radiated bass.

 

I'm amazed at your ability to analyse and "debug" your FLACs. I've always had Ardour installed as I'd need it at some point (got lots of vinyl). but your step by step allowed me to play with this stuff. What amazed me was just how poorly mastered some of my music is. Well no wonder it sound like a$$, it's a complete solid bar from top to bottom. I see you are remastering some of your stuff track by track. Have you automated this process as it seems to be quite time consuming to figure what is required to re-equalize. I ended up making a "house curve" that puts stuff where I like it. Hat's off to you, as one can make something that sounds terrible and make it passable. I can hear the DR improvements on well mastered rips. Just gonna have to retire to get the time.

 

I tried all of the multi-channel audio and video stuff but it's just not my bag. Two channel large format horns for me!

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Before Heyser came onto the scene, nobody in the industry cared about the time domain because they had no way to quantify it.

I just heard a lecture on Heyser and saw a newly uncovered lecture that was recorded. He had to start with fundamentals of science because he was being ignored for having such wild views. Now we take it all for granted, and those that knew him feel there is more to the story. We just don't have anyone smart enough to continue his work.

PWK's old views are just plain wrong, but I have a feeling he warmed up to these ideas in the later years....only problem is he wasn't writing articles like everyone was back in the 70's. Or maybe he never changed his views, who knows.

Edited by DrWho
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Got to appreciate those type of folks who think so far outside the box, that they can explain stuff that is difficult for normal folks to wrap their head around, so thanks for the tip on Mr. Heyser.  I'm sure the answer to my question of why one's recorded voice doesn't sound like your voice when played back to you is somewhere in the many PDF's I grabbed. How can one not be familiar with ones own voice? This has GOT to be some kind of voodoo audio trickery gone wrong somewhere between ear and brain.

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Anyone here using a bi-amp setup with just two amps and running the highs and mids together?

Jay

Jay I am doing that. I took out the gold connecting bands. I am using a Hafler DH-200 to drive mid/tweeters (100 watts per channel with 2.5 dynamic range around 250 watts) and a Carver M-200 to drive woofers (201 watts per channel with a 1.9 dynamic range around 293 watts). I use a Hafler DH-100 Series 2 (I have a Series 1 I am fiddling with) Preamplifiers to drive them. My Preamp uses very simple separate Bass and Treble controls that raise or lowers +/- 10dBs Bass from 20Hz to its upper limit and Treble (Mid/Tweeters) from 1000Hz up to 24kHz. The sound is great when I turn up the Bass it just gets tighter until I use too much then it muddies while turn up the Treble and everything becomes more focused and if I use it too little the sound becomes muddy again while turning it up all the way it does not clip rather the sound becomes lousy (disjointed?). Doing this division everything is allowed to work better than the specs in many cases producing an excellent sound stage! I am so much happier with music now. (My Klipsch R-28F's split the mids with the highs from the bass just by taking out the gold connection bands)

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I see you are remastering some of your stuff track by track. Have you automated this process as it seems to be quite time consuming to figure what is required to re-equalize.

 

I could batch process some tracks that I find that have unchanging EQ curves for most tracks, but I've found that batch processing would do more harm than good.  Each album and each track is more or less different in some way, and sometimes those differences require changes to some aspect of the process.  I've found that listening to each remastered track most of the way through is really a requirement.  Otherwise something important is missed and a really wrong correction to the tracks is applied and saved, thus compounding issues later when I come back at a later date and listen, then realize that I have to do more work on them.  Sometimes I found it was a bit embarrassing to play some of the earliest work that I did for my friends and family, not originally hearing the defects in the original corrections until days later.  That also causes you to get better and use better processes, to spend a little time initially to get it right, and to listen carefully before saving the updated tracks.  Batch processing would significantly multiply the pain of the corrections that have to be made later.

 

For me, these music tracks are the reason why I assembled my music system.  In general, they have a high enough value for me to do the best job that I can.  Some of them have been a part of my life now for a very long time and define my recollections of life.  In other words, they're important.  Other music tracks--well maybe not so important, but still important enough to edit them one at a time.  If they're not that important, I don't bother spending time on them at all and don't really listen to them.

 

Chris

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OK, so your basically doing a Chris's Greatest Hits. It took me about six months to get through about 50gig of my 650gig collection, and yup, I dorked a few up as well. I ended up with two curves, your classic missing octave curve, and one that did that and reduced mids and highs on a slow curve up from -6db @ 100hz to -3db. That seemed to cover most cases.

 

I chilled out realizing I may not get through the whole collection. I guess I'll regroup and take your approach. I have a playlist of favorites that weighs in at about 5000 tunes, problem is I just started that recently. This is the only time I ever acknowledged that yes, you can have too much music!

 

Never understood what the heck a phono preamp did until looked at the curve in Audacity (think I called it Ardour in an earlier post).

-bill

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OK, so your basically doing a Chris's Greatest Hits.

 

Well I'm planning on remastering about ~80% of my disc inventory, if that gives you a better idea.

 

It took me about six months to get through about 50gig of my 650gig collection, and yup, I dorked a few up as well. I ended up with two curves,

 

I usually have a resulting target curve that varies for each album, sometimes for each track.  I'll explain more over on the missing octave thread when I finish up with another task that I've promised to someone.

 

Chris

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"The pace, rhythm and timing of an amplifier (PRAT) need to match.

PP and SET do not match up well.

Amps with no global feedback do not match up well with amps with global feedback. "

 

I am glad this old thread was brought back up. I think most of have always believed SS was best at bass reproduction & tubes had the best mid range, or at least that was my experience. Since I started down the bi amp road I have never tried a different amp for my bass, thinking at the very least my Crown K2 was a good choice for the bottom end. . I have tried several different amps on the top end with very noticeable differences. If the quote above by djk is correct I have been missing out on another opportunity for improvement. My set amps on the top are zero feedback & the Crown has a dampening factor of 300.

Would love to hear from other bi amper's of there experience that they have tried matching both amp's with no feedback or not matching.

Need to get motivated & dig out some of my other zero feed back amps & try them on the bass. May bee the Bat vk60 or the Moondogs (uppps just sold the Dogies) :rolleyes: Dang sold the First watt F3 as well - live an learn.

 

Well i managed to get about 20 hours on a new Decware Torii PP 25 watt dual mono on my Cornwall III's. This PP is voiced very closely to the Rachael that I have around 40 hours on. Both have the stock tubes. Lots of EL34s and 5U4s in here. Straight out of the pelican case, this thing was already throwing out a great image.

 

I finished re-configuring everything this afternoon. Have the Rachael's variable output feeding an input one on the Torii for a full tube bi-amp of Cornwall base box with an Eminence N320T/Selinium bi-radial midrange, and a B&C DE120/Faital Pro elliptical HF. Feeding the Rachael with the dedicated stereo outputs of an Oppo 105. Connected digital coax to the Oppo is an M-Audio sound card. Straight FLAC 44.1 Redbook rips.

 

For a system that isn't even close to being broken in, this is nuts!

 

I'm really looking forward to getting some serious time on this setup.

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  • 1 month later...

“Do I need to disconnect my speakers’ passive crossovers from my drivers?"


Yes. At least the woofer (or low frequency driver) must be disconnected from the passive crossover to permit bi-amping. If your speakers are 3-way (i.e., woofer, midrange, tweeter in each cabinet), then you may retain the passive crossover between the midrange and the tweeter if using bi-amping (…but for tri-amping, all drivers must be disconnected from the passive crossover networks)


 


Hi All - looking for a little more elaboration on the above statement as I look to biamp my Heresy IIIs.


 


To disconnect the woofer from the passive crossover, is this just a matter of removing the coupling links from the speaker-wire binding posts, or do I need to modify the actual crossover wiring within the speaker enclosure?


 


Also, I'm planning on using an Ashly XR-1000 crossover and targetting 850Hz as the crossover point - does anyone have any experience (or views) on the appropriate crossover frequency for the bass driver on the Heresy IIIs?


 


Cheers,


Nick


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The unit that you speak of (Ashly XR-1000) appears to be a stereo 2-in, 4-out analog crossover.  Using that unit on Heresy IIIs would entail disconnecting the woofers from their passive crossovers (i.e., not connected) and the midrange+tweeter in each speaker would be connected to the passive crossovers, resulting in bi-amplified Heresy IIIs.

 

The 850 Hz crossover point would be the necessary crossover point to the woofers using the Ashly XR-1000 since the passive crossovers to the midrange drivers would still be crossing at that point (high pass).

 

Otherwise, you would need to remove the passive crossover connections entirely and tri-amp them using a 2-in, 6-out active crossover.  In that case, if you were using a digital active crossover, then you could dial in delay for the tweeter and the woofer to compensate for the midrange horn delay.  Then you could set the crossover points at will.

 

Chris

Edited by Chris A
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