Raising the While Flag on 604 Project

[Seadweller]

The room appears to be overly "bright"...bare walls, no drapes, bare floor, etc. Have you tested them in any other rooms?

Indeed, the room is somewhat bright...There's quite a bit of furniture in the room, and a carpet that covers a large portion of the floor, but there are no wall coverings. Unfortunately, I don't have another room in the house that's any better (or, where they'll fit )

My prior speakers, in the same location, worked fine however. In some cases, the bass output was too high. I think the shoutiness is more XO or driver related than room related, because it's evident even at low listening levels, with a listening position closer to the speakers.

[Seadweller]

The top couple of octaves will also diminish as you turn the high frequency driver down, but these can be restored with work on the crossover, bypass caps etc. It is most important to get the vocals right, the rest can follow.

Thanks for the great input Steve...Unfortunately, this is where I fall flat on my face. I know nothing about crossover design, so I've been providing anecdotal data to the gentleman that's been working on them...I'm in Florida, and the crossover designer is in Chicago, so I provide comments, ship the XO to Chicago, he makes changes, ships them back, and the process has gone on for some time now.

I have a CD with incredible female vocals, and listening to it through this system will give you goosebumps. I've noticed when dialing down the horn, that the high frequencies suffer, and the "air" and "sparkle" is lost. I believe my latest XO was designed to allow the horn to be adjusted, while a lift circuit restored the highs, which is I believe what you suggested.

If I could make these XO adjustments myself, I'm sure I could tweak the system until it was right, but I wouldn't even know where to begin. Ultimately, this is a stumbling block I haven't figured how to circumvent.

[oface1]

Seadweller,

have looked at your speaker connections? Sounds maybe there "might " be a phase issue.

I had a similar problem with another set of speakers....

sorry if you have all ready went through the trouble.

I have 604-8k's and at very low volume the bass is a little anemic, but when I crank it up , I get bass. Plus it looks like I will have to do some acoustic panels to help tune the room. I have a bass nodes when I walk around. DO you notice an increase/decrease in the BW when you walk around while listening?

-chris

[Seadweller]

Seadweller,

have looked at your speaker connections? Sounds maybe there "might " be a phase issue.

Hi Chris,

Yep, I've gone through the connections 100 times at least! I do notice that the bass improves in the very back of the room, but I'm sure that's normal. Some CD's have more bass than others, but in general, the bass output is much weaker than my previous pair of speakers.

It seems that the low bass output, and excessive midrange output have combined to create one heck of an issue to overcome..

[oface1]

Hmm...

Well, I can tell you that my 604's (in 620 A cabs, using the older GPA XO), do not have the slam/impact in the bass region that I was used too, but it is there....

And just like you, I got to the back of my room and there is the bass, just rattling the walls (music depending),

But when I go to my listening position, it is not as pronounced.....

when you say the bass is weaker, can you give a factor maybe?I know that he 604 isn't suppose the be the last thing in BW dynamics, & and there is a significant drop below ~40 Hz.....Have you tried using a Active XO or any other Eq to adjust to taste?


-chris

[aeyb701]

Good day:
You mentioned insulation-too much can hinder bass extension in my experience-typical thing is to line one opposing side of each pair of sides from what I've gleaned on this site over the years.
I didn't read if you were using new GPA drivers or 604-8K's, when I glanced back briefly. New drivers may have very stiff suspension, as I know from a 604C re-cone from GPA versus the springiness of the original cone. This may or may not affect LF response, and if so does it need time and use to improve? I don't know and have not been able to tell from a forum search. I have not used mine long enough to tell.
What about trying original Altec 604-8K crossovers, without the tweaks? I have -8K's in Stonehenge-style aftermarket enclosures, about 8 cu. ft., with orig. Xovers and they sound great- strong bass is there when the program calls for it, but no bass hints or boom ("undertones"?) when there is no bass info.
-Jon Archibald

[vuki]

Hi,
few months ago friend of mine bought GPA604-8hII. He built 10cu ft. boxes and decided to use Jeff Markwart's crossover design. To make a long story short - it was disaster.
Very bright (no bass), extremely colorated midrange - unlistenable. He asked me for a help.
Measurements revealed the situation I just described. So, after a bit of measureing, soldering and listening here is what I came up with. It measures pretty linear and sounds excellent. Anyway - I think it's worth a try if not satisfied with stock (GPA) or any other crossover.

[Panomaniac]

Hey, maybe we've got you back on the horse! :2thumbsup:

If you really want to tweak, you should get a Behringer DCX2496 and an extra amp. You may already have the amp. You can always sell the DCX2496 after if you don't want to keep it.

I got a pretty nice sounding rig going with the 604-8K and the DCX crossover. No lack of bass, not shouty. Good imaging. Those drivers should be close enough to your 604-8H to be no problem. My crossover points were 1160Hz on the woofer, 1530Hz on the horn. 3rd order butterworth. Some shelving EQ on the woofer and the horn. 28mm delay on the woofer.

With the DCX2496 you can tweak to your heart's content and we could even help. Once you get what you like, a passive crossover could be built. I feel for your crossover guy. Doing it long distance like that is super hard.

[Seadweller]

when you say the bass is weaker, can you give a factor maybe?I know that he 604 isn't suppose the be the last thing in BW dynamics, & and there is a significant drop below ~40 Hz.....Have you tried using a Active XO or any other Eq to adjust to taste?

-chris

Hi Chris,

I find the 604's to be much more dynamic than any of the other speakers I've owned, except of course for my Model 19's that I foolishly sold many years ago. What I like about these drivers is the liveliness of the presentation, which to me, provides greater dynamic swings than many other speakers.

I owned VonSchweikert VR-4's, and while they were an excellent system with incredible bass response, they were very subdued. If I gave the VR-4's a 10 for bass, my current 604 system would probably rank a 4 or 5 overall. I just can't figure out why I'm lacking bass using an enclosure of this size!

I went the "purist" route many years ago, buying stuff without tone controls, etc., but it has crossed my mind to try an active XO or equalizer. I've even considered one of the XO's that you set up the mic's in the room, and it automatically determines the proper settings, but I would suspect they're expensive, and I already have a small fortune invested in these speakers as it is.

I took the "money is no object" approach with the cabinets, because I thought this was the last speaker system I'd ever buy!

[Seadweller]

Good day:
You mentioned insulation-too much can hinder bass extension in my experience-typical thing is to line one opposing side of each pair of sides from what I've gleaned on this site over the years.

Hi Jon,

Yep, that's correct...I have insulation only on the top, one side wall, and real wall of the cabinet...