6 dB per Octave Passive Crossovers

**LowOhms** · January 11th, 2013, 01:03 AM

Originally Posted by RonSSS

I never cared for biamping my M19's either. And I used identical amps for highs and lows. PP 6B4G modified Heath W5's. No sand amps in my system. The issue was probably my x-overs, but just never messed with the whole thing because the stock x-over just sounded better.
I have messed with 6db slope stuff. On A7's as well. But the woofer section has a peak at 250-300hz, and that just became accentuated. To my ears anyway.
So Jeff, do it and have fun and tell us what you hear.
Ron

Did you see how Dominique ( as posted on this Forum ) measured a huge peak, maybe 10 dB at around 240 HZ? As soon as he put three-sided wings on, it measured 4 dB less. He also ( IIRC) added a felt damping material - hanging inside the bass enclosure, and got it even better.

He was guessing it has to do with the frequency of the horn mouth, as determined by the distances, and wave lengths. When you add wings, it ameliorates this 240 HZ peak some, but not completely. ( It makes the bass horn mouth " look " larger. ) So Ron, I am guessing the problem you discuss is probably a function of the enclosure being only partially horn loaded, and not so much a crossover thing. My guess, I am not a speaker guru !!

Thanks for posting. Larry D. Moore nicely covers this 6 dB stuff, sorta interesting to read his Issue Six.

Jeff

**mah** · January 11th, 2013, 01:17 AM

LowOhms, your statement, "Please don't let the many Forum members, with huge listening rooms, solid state(sic) amps and active equalizers scare you off!! Allow your minority voice to be heard". would not be a good way to win friends on any forum. You have, in your first post, made a generalised slur on many of this forums members. I think the response has been quite gentle considering the double exclamation mark you used for additional emphasis.

Now, back to the topic.....................

**LowOhms** · January 11th, 2013, 01:21 AM

Originally Posted by SD-50

Also benefit from a 6db xo on my A7s. The original Altec xo's were missing when I bought the used A7s; the 12db after-market replacements were dreadful. At any rate, following countless hours of trail and error settled on the 6db xo, at approximately 600hz as the most musical, transparent, and dynamic XO I could cobble together without any sort of test gear, other than my ears. Power handling is not an issue as I rarely listen above loud conversation level.
No doubt, there are issues with the xo that need to be rectify, but without proper test gear and a lack of technical skills, it?s just not going to happen.
I?ll post a drawing of the xo later, welcome all comments, useful or otherwise.
Cheers

Hi SD 50 !!!

Yours was a post I was looking for. There must be others too. You and Larry Moore settled on a similar approach...by ear. Yes, others would like to see your schematic.

I am so HAPPY you responded.

There are two things I'd like to send you, if you are open to looking them over. One would be Larry D. Moore Esquire's A7 write up, done a number of years ago. Another is a SERIES crossover " primer ", two way and three way at 6 dB, instead of the usual Parallel passive crossovers. The same parts are employed, just minor / different wiring. Some ( Dominique, Paul Eizak, Bud Fried ) say SERIES sounds superior. Just need your email address, to send the info. as attachments. ( Any one else is welcome to it. )

What ALTEC components do you run? What power amps do you use ? Curious minds want to know. THANKS for posting sir.

Jeff

**cradeldorf** · January 11th, 2013, 01:57 AM

(Insert Popcorn eating emoticon here)

**RonSSS** · January 11th, 2013, 02:15 AM

Originally Posted by LowOhms

Did you see how Dominique ( as posted on this Forum ) measured a huge peak, maybe 10 dB at around 240 HZ? As soon as he put three-sided wings on, it measured 4 dB less. He also ( IIRC) added a felt damping material - hanging inside the bass enclosure, and got it even better.

He was guessing it has to do with the frequency of the horn mouth, as determined by the distances, and wave lengths. When you add wings, it ameliorates this 240 HZ peak some, but not completely. ( It makes the bass horn mouth " look " larger. ) So Ron, I am guessing the problem you discuss is probably a function of the enclosure being only partially horn loaded, and not so much a crossover thing. My guess, I am not a speaker guru !!

Thanks for posting. Larry D. Moore nicely covers this 6 dB stuff, sorta interesting to read his Issue Six.

Jeff

Strictly enclosure thing. I think it's pretty well documented. I measured it. Basically why I'm not an A7 fan....I use an EQ to tune it out.
I actually have a pair of a7's now, and that's what I'm doing. But these are used for TV mostly, not really hi fi.
I'm honestly thinking A7's are going to frustrate you. But play on! I bet you would love some duplexes better.
Ron

**LowOhms** · January 11th, 2013, 02:17 AM

Originally Posted by mah

LowOhms, your statement, "Please don't let the many Forum members, with huge listening rooms, solid state(sic) amps and active equalizers scare you off!! Allow your minority voice to be heard". would not be a good way to win friends on any forum. You have, in your first post, made a generalised slur on many of this forums members. I think the response has been quite gentle considering the double exclamation mark you used for additional emphasis.

Now, back to the topic.....................

Perfectly good point and I agree. Its hard doing things by typing. It was said in jest, and there is no way I can show that inflection, except, if I put a smiley behind the end of the sentence, which seemed corny at the time to me. Wish I had. I apologize to any and all I offended. You are very right about that.

Yes, back to the topic, THANKS for pointing that out to me.

Jeff

**LowOhms** · January 11th, 2013, 02:36 AM

Originally Posted by RonSSS

Strictly enclosure thing. I think it's pretty well documented. I measured it. Basically why I'm not an A7 fan....I use an EQ to tune it out.
I actually have a pair of a7's now, and that's what I'm doing. But these are used for TV mostly, not really hi fi.
I'm honestly thinking A7's are going to frustrate you. But play on! I bet you would love some duplexes better.
Ron

I've heard GPA duplexes in very well-made MLTLs on SOTA gear, and there is a lot to be said for a point source. Recall, I grew up with 604Bs as a child.

Ron, I hear a SMALL discontinuity in the midrange, I am guessing where the two drivers cross over, that makes me think I would not be pleased, long term with them. I am very open to the idea of a duplex, but I am scared to death to commit from what I have heard at RMAFs, the last six years. Maybe I will learn from Forum members, new facts on 604s, or combinations thereof, unknown to me presently. Its an "open" thing for me as of now.

YES, I was guessing, up-front that A7s are a risk. If money was not a factor, I'd run a good Danley Synergy horn. Oh well, the money is a factor.

Jeff

**mah** · January 11th, 2013, 02:47 AM

FYI: 3-way, all 6dB/octave, with Altec 515G

6moons industry features: La Grande Castine

**Old Guy** · January 11th, 2013, 05:10 AM

Originally Posted by badtoby

Can't we all just ..... Get along? And have a good time.

Sorry...but I work methodically. Irritated by amps with different timings? Then use amps with the same timings, Easy. But to scrap an entire concept after doing it badly by throwing stuff together, then crowing about how bad the concept is, just makes me wanna say, Hey, got things to do better than putting up with you.

Bad plans equal bad results, but no plans equal worse results than bad plans.

I don't have bad feelings towards Jeff, just got better things to do.