gpa 604 8H II crossovers again, sorry

[Tom Brennan]

Originally posted by DNV47:
but I'm surprised you don't think that caps in an xover can change sonics.

<font size="2" face="Verdana, Helvetica, sans-serif">I'm not claiming that caps don't effect sonics but the OP's problem may be a frequency response problem, one of balance as another poster said, and changing caps in the hopes of finding one that acts as an equalizer, and a proper equalizer at that, seems a pretty willy-nilly way to go about solving such a problem.

Right now I'm having a similar problem with some 605As in a certain room in my house. In my other houses these speakers sounded great but in this room I can'r get them balanced right.

The speakers are bi-amped so I have 2 adjustments there; crossover point and high-low balance. And I also added an outboard EQ to replace the compensation networks on the compression drivers. But I have a problem that when the highs are of sufficient level the speakers sound harsh and "earwirey". The only way to get them to not sound nasty is to turn the treble amp down to where the speakers then sound kind'a muffled. That or EQ the highs away. Neither is a good solution.

I never had this kind of room problem before.

[DNV47]

Ya know Tom, that sounds like a problem I had that drove me nuts for months. It turned out to be a phase problem between 802's and tweeters.
The 802 diaphram is mounted backwards compared to some other brand compression drivers and I kept forgetting that. Once I reversed the black and red wires on the tweeters everything fell into place right away and the correct sounding xover point that I could never find before took me about 10 minutes to find by trying different cap values. (6db/octave)
I wonder if in your bi-amping setup you don't have a similar problem? Don't some amps invert the signal and others don't?
But if your using a two way maybe that's not it.
I was the one that posted that maybe the OP had a level problem because it looks like the GPA xover isn't adjustable with a pot.
His original post said it was suggested to him to use oil caps to tame things down. While that might work I agree that it's "willy nilly" unless your pretty much in the "ballpark" of what your looking.
Todd and Gary's posts regarding good/bad and forward sound opens the personal taste door.
Not everyone likes a more forward speaker and some just hate horns period so if the OP isn't in the muffled camp I'd like to hear if he ever gets his problem fixed and how.
Lots of people say they love Bozaks yet so many of them are trying to get more out of the tweeters or replacing tweeters.
I worked for Bozak and Mr Bozak firmly believed his speakers were accurate as is and he frequently talked about the west coast east coast sound.
I guess we're the dreaded west coast people with Altecs!
Then there were the AR ads showing Miles Davis with his AR3a's saying that he knows what his horn sounds like and AR's reproduce it.
My neighbor has homemade Valencias and the literature that came with the drivers says that the 806 goes out to 20KHZ so he thinks he's listening to a true full range speaker and doesn't want to hear where the 806 starts dropping off and by how much so obviously the exaggerated mids do it for him.

[Todd W. White]

I liked to express it to my customers this way -

Altec speakers paint the entire audio picture of the source material you put into them - warts and all!

[DNV47]

Just thought I'd mention the phase thing. In my case with a 3 way, the difference in tweeter phase reversal was not subtle. The thin shrill sound while other things sounded right was instantly gone and I got a smooth presentation where eveything just sounds right with decent recordings.

I also wanted to add to my last post that sonic tastes can change too so I'm personally not overly critical of what other people like to hear because if they are happy, that's the whole point regardless of how their system sounds to me.

My first "real speakers" of note were bi-amped Bozak 4000's. Snappy cracky and tight bass to die for, OK but maybe slightly forward mids and lack of highs. Male vocals A+++.

I had some of the earliest Z tweeters made at the Bozak factory in Norwalk,CT and they were tested by engineering. Too bad they didn't tell me that although the response was smoothed out and extended they were less efficient than the previous tweeters.
I would have been much better off with the Y's.

Then my modified AR LST's were the cats meow until I felt I wanted a more open and dynamic sound with different bass and EV Regencys were my speaker of choice.

A friend wanted to get rid of his Flamencos so he brought them over and I heard something I liked but also heard a lack of real highs and that's when the EV T350's came out of the Regencys.

Then the Flamencos got on my nerves because the bass wasn't right and the mids were too aggressive so I jumped into Model 19's with added tweeters crossed over very, very high at 6db/octave and now I feel I have the best yet but for how long?

I remember someone at work bought a pair of smallish Klipsch 3 way speakers and to listen to them was extremly painful and I always wondered if those were the buzzsaw speakers you mention a lot. It made me wonder how any speaker company could think they were OK to sell but I guess they sold.

Then there were the big expensive B&W's I heard and couldn't take more than a minute of that incorherent noise.

Then there's the $55,000 a pair speakers I played with. BORING and a $7 BSR equalizer from Goodwill tweaked up at the speaker xover point made them at least listenable but they were still seriously lacking in dynamics.

To each their own for sure.

I do hope the OP informs us of any progress in his quest because now I'm really curious about what it is he's hearing that he doesn't like and what the cause was.

[mondonitro]

Hey all, thanks for the responses! I did get in touch with Steven at GPA he has generously provided the schematic and suggested trying a resistor swap were the mid frequency control would normally go. Swap the 18ohm for a 10 ohm should send more to ground and bring down the region that seems to be trouble some. Seems caps flavor the stew while crossover design give it its taste. Steven said most people love the crossover as it is. They have worked hard to take care of the past issues with these drivers. So I think that is where I will start, then on to different caps, oilers most likely. I may be one of those "people that hear" that region more pronouncedly. Everybodys ears are a different shape and have been subjected to different damages ( IE:minutemen at the Mistake in 1983) so I'm convinced we hear different .I'm building some 9ft MLTL cabs also and we will see where that takes me. This crossover seems optomized for the cab I have now, 6 ft BR. ( this is their recomend) But I love this hobbie, playing around is 30% of the fun, 30% finding new music and 40% actually listening. I can research and make drawings and plans while traveling for work, but its hard to listen to my rig when I'm in La for a job and my gear is home in Chicago. Thanks everybody

[Tom Brennan]

Interesting DNV. I'll play with the phase reversal switching on the crossover.

I used to have a set of Bozak coaxials and while I loved the midrange the tweeters sounded wirey. They were the aluminum tweeters and I thought that perhaps the rubber dampers behind the cones had deteriorated letting the cones "run away" so to speak.

The midrange and vocal reproduction was first rate though. I don't have them anymore, I gave them to a young fella I ran into at Magnetar's house. At the time ole Magnetar was using 15" Beyma coaxials along with another 15 in big JBL style double 15 scoops. The sound was...interesting.

[Seadweller]

I have the same issue with my system using the stock GPA crossover...The midrange is way too hot...The range where vocals exist is so forward that it's actually "shouty," and it overwhelms the rest of the spectrum to the point that everything else is out of balance, from bass to highs...

Interestingly, I was listening to a CD and was floored by the detail; the impact of the percussion, and the "almost there" presence these drivers provide...When the vocals began, I had to stop listening to the song, they are that forward...

I'd be very interested to know how that resistor swap works out...I'm toying with building either a 3rd or 4th order design that Stephaen kindly provided the schematics on...I feel like I'm just a step away from nirvana, but I'm still not sure which direction to go...

[Todd W. White]

Are you sure your system is running without any tone controls/eq's in the circuit?

A lot of people get used to setting their system up a certain way, then, when they replace a component, complain, never realizing their system is still "tuned" for the item they replaced.

Don't forget - it could be the recording. Have you duplicated the problem with multiple recordings of vocals in different musical genre?

[mondonitro]

Hey Todd, I have a comp cd that I use when I go to CES every year. So I am using music that I am very very familar with and have heard on at least 20 different high end systems ranging from anything such as Manley/Coincendent to full avantgarde trio, Wilson Watt/ VTL , Emerald physics CS 2, Cain Cain, lowthers you name it, if I could get my disk playing I did. My fave...Avantagarde Trio. So I guess I like horns. The music ranges from male roots rock,avant guitar, local fave Patrica Barber ( so I have a live reference, plays every Monday 5 blocks from my crib ) everything but not alot of classical. It is not the associated gear, I have a EICO HF 81 and that has tone controls, with the treble down it still shouts, not as bad as the Melody but it is "hot in that vocal range". I have not "trained myself to like bad sound" I know the difference. So as soon as I get a chance I'll order up some resistors and make the swap. Then play with 3rd order if I have to. By the way the EICO is suprisingly good, I feel a real synergy with that combo, better than the Melody I 2a3 for sure. I do think oil caps will help the stock crossover. I can't find any info on the stock caps, Bosun I believe. I'll report back as I update the changes. Thanks Pete

[mah]

This 604 project may be of assistance:

http://www.6moons.com/audioreviews/altec/dream_3.html

Marshall.