Raising the While Flag on 604 Project

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Originally Posted by GM

For some reason I thought you cloned Jay Fisher's MLTL, but the driver is in the wrong place, so to answer your Q I need to know the cab's net Vb and the port's length.

GM

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Thanks GM. Indeed, I did clone Jay Fisher's MLTL. He was incredibly generous with his time and advice, and actually guided me through the construction details.

His instructions were explicit; to mount the driver so the center was exactly 19.625" from the inside top of the cabinet. The cabinet's internal height is 42.5" and my cabinet maker adhered strictly to these dimensions.

Best I can tell, if you take the insulation into account, the cabinets are around 9.9 cubic feet. They are around 10.4 cubic feet in raw dimension. Jay told me to keep the CSA at around 426. Currently the port is 6" in diameter, and 3/4" long (basically, the width of the bottom panel). I also have the 3 ohm resistor in place as instructed.

Jay's instructions were to have the port 6" round, and 2" in length, but I have not trimmed the 6" x 6" port tube inserts that I bought. I tried inserting them into the port hole, but they had no affect. I can't imagine trimming them down to 2" would matter, but again, I'm a complete novice with this stuff! :)

You're welcome!

Going back to some docs and the MathCad sim I see you're right, we even had some correspondence about it, but I was comparing the pic he sent to yours which clearly shows it higher up, so for whatever reason he apparently didn't follow the plan: http://farm5.static.flickr.com/4014/...30408f64_b.jpg

Regardless, changing the vent from 0.75" to 2" long doesn't change the response a lot, so probably only noticeable when a 42 Hz tone of appreciable output is generated, but a 6" long vent drops Fb ~10 Hz, turning it into a near sealed alignment with F3 rising enough for a 3-4 dB loss at ~42 Hz which should be audible. Not night n' day, but a worthwhile difference if you've got some room 'boom' to deal with and the driver is less likely to audibly unload playing pipe organ symphonies.

If you're not hearing any change, then you've got one or more leaks that needs plugging.

WRT insulation, it not only doesn't decrease the acoustic volume, but up to a point actually increases what the driver 'feels': http://web.archive.org/web/200210070...ces/fiberfill/

GM

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Originally Posted by GM

You're welcome!

Going back to some docs and the MathCad sim I see you're right, we even had some correspondence about it, but I was comparing the pic he sent to yours which clearly shows it higher up, so for whatever reason he apparently didn't follow the plan: http://farm5.static.flickr.com/4014/...30408f64_b.jpg

Regardless, changing the vent from 0.75" to 2" long doesn't change the response a lot, so probably only noticeable when a 42 Hz tone of appreciable output is generated, but a 6" long vent drops Fb ~10 Hz, turning it into a near sealed alignment with F3 rising enough for a 3-4 dB loss at ~42 Hz which should be audible. Not night n' day, but a worthwhile difference if you've got some room 'boom' to deal with and the driver is less likely to audibly unload playing pipe organ symphonies.

If you're not hearing any change, then you've got one or more leaks that needs plugging.

WRT insulation, it not only doesn't decrease the acoustic volume, but up to a point actually increases what the driver 'feels': http://web.archive.org/web/200210070...ces/fiberfill/

GM

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I was going to mention that about the stuffing. One can change the amount to change the finger rap on the cone from a thump to more of a whack....you have to try it.

Also, a simple sine wave generator, a DVM, a power amp and a 100 ohm resistor can measure the box tuning.

A port firing down into the floor, especially hardwod makes no sense to me.. In a box that large, firing forward makes more sense. Especially in a "hard" room like you have. The room is such a big part of the equation.

I built 8ft^3 boxes for my 411 subs. Also used a 6" round tube port. 8" long worked the best.......

I saw quite a diff from a 1" length to the 8" length. In fact, these are so cheap, you can cut them down and duct tape them together to make them longer.

3/4 of an inch is the thickness of the cab.

The TS parameters I measured for the reconed by GPA were no where near the stock specs, more like a 416, and the tuning worked well. I tuned them to 20hz.

I just don't get the downward firing port.

Ron

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Originally Posted by RonSSS

I just don't get the downward firing port.

Ron

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Hi Ron,

Evidently, the downward firing port is intended to use the floor for boundary reinforcement in the low registers. I was experimenting with different cabinet designs, and was actually going to make a conventional tower cabinet with a false bottom (to maintain the 42.5" internal cabinet height), and a foward firing port.

In the end, because of the sheer size of the cabinets, I decided to go with my current design, both to take advantage of the boundary reinforcement, and also to give the cabinets a less "monolithic" look. I really didn't realize how big these were until I got them home. Even my wife was speechless! :)

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Originally Posted by GM

If you're not hearing any change, then you've got one or more leaks that needs plugging.

GM

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Thanks GM. I guess it's possible that the changes could be too subtle for me to detect, or even more likely, that the excessive midrange energy is masking it.

Honestly, if worse comes to worse, I could add a subwoofer to the system to fill in that gap, but it's the midrange output that I've been unable to address.

I've had numerous folks tell me that I'm nuts, and that they've not experienced this effect with these drivers, but I'm telling you, there is a range of frequencies that when a voice or instrument fall in that range, the beaming is like the phaser on the Enterprise. It would cut through solid titanium.

Of course, my preference would be to get this system correct without the use of a subwoofer, as I like the minimalist style of the speakers, and I've really no room for a decent subwoofer.

Actually, for my own curiosity, would a passive radiator mounted in the bottom of the cabinet be an option? Or how about an active driver? Perhaps mount a 416 in place of the downward firing port? I'm not sure how it would interact with the other driver, but I'm just throwing spaghetti against the wall!

You're problem might not be your speakers but your amplifier. I remember in the 70's students testing all kinds of receivers they had purchased on A-7 and none sounded the same . The worse was Technics.

For low Price budget Harman Kardon Receiver 100 Watts per channel.
In the higher end Bryston and Mcintosh.


By the way Toyota run away car has to do with cheap electronics .

When buying an amp be careful where it is built.

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Originally Posted by Seadweller

I've had numerous folks tell me that I'm nuts, and that they've not experienced this effect with these drivers, but I'm telling you, there is a range of frequencies that when a voice or instrument fall in that range, the beaming is like the phaser on the Enterprise. It would cut through solid titanium.

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I don't think you're nuts. I heard about the same thing from a 604-based speaker at RMAF in 2008 -- honestly, I thought they were just awful. I was both stunned and saddened, as I had been really, REALLY looking forward to hearing them. No idea if the mfg is using their own crossover or GPA's, but for me it eliceted instant listener fatigue each of the 4 or 5 times I went by the room.

Chris Mecurio has posted about what a great job Rick Craig at Selah Audio has done in terms of designing a custom crossover for his pair of GPA 604H-III. Maybe you could contact Rick to see if he'd do one for the II's.

Regards,
John

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Originally Posted by LICORNE

You're problem might not be your speakers but your amplifier.

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I began this process with a Parasound A-21, which was an incredible amplifier. An overwhelming majority felt that the low output impedance was impacting the bass, so reluctantly, I sold it, along with my pre-amp, and bought a Cary SLI-80 integrated, also a highly respected amplifier.

I can't say that the tube amp did much for the bass output, and I ran it in both ultralinear and triode mode. I think this time around I'm going to get a SS integrated, and steer away from separates.

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Originally Posted by nullspace

I don't think you're nuts. I heard about the same thing from a 604-based speaker at RMAF in 2008 -- honestly, I thought they were just awful. I was both stunned and saddened, as I had been really, REALLY looking forward to hearing them. No idea if the mfg is using their own crossover or GPA's, but for me it eliceted instant listener fatigue each of the 4 or 5 times I went by the room.

Regards,
John

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Hi John,

Indeed, I'm facing that very issue. It's a little disconcerting that I have this magnificent pair of speakers that I can't tolerate listening to. I can't even get through half a song. I find myself changing out CD's, one after another, desperately trying to find something I can listen to. After about 20 one-quarter songs, and 10 CD swaps, I get dejected and end up just turning the system off.

Interestingly, the system in its currrent form does OK with jazz. While I still get the excessive midrange energy, it's the voices that really cut you in two.

I wonder if you listened to the system made by Serious Stereo out of Montana. They are using the exact cabinet I'm using, however I understand they are using an XO based on the Great Plains version.

When mentioned friend got drivers and enclosures he built jeff markwart's crossover and he was so confident in good result that he immediately bought expensive boutique parts. It was really unlistenable - just as you decribed - no bass with strong highly colored mids and dirty highs.
As I can see Jeff Markwart is a quite serious man, so I doubt that he made his crossover plans without listening and measureing. What I suspect is that he got some early version of GPA driver that was different from the current ones - that's the only logical explanation for such an awful sound.

Anyway - as Panomaniac said; buy the cheapest parts for my crossover (ferrite inductors, wirewound resistors and MKT caps or even bipolar elcos) and put it together "in the air" - you don't have to solder- use screw terminal strips if you like.

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Originally Posted by vuki

Anyway - as Panomaniac said; buy the cheapest parts for my crossover (ferrite inductors, wirewound resistors and MKT caps or even bipolar elcos) and put it together "in the air" - you don't have to solder- use screw terminal strips if you like.

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Thanks vuki! I'm going to give your XO a try, and order the parts today, but I need some help on the parts list, as I'm unfamiliar with some of the resistor and capacitor values. Let me know if this parts list is accurate. I put a question mark where I'm unsure:

Caps
C1 = 2uf
C2 = 15uf
C3 = 6uf
C4 = 15uf

Inductors
L1 = 3.6mh
L2 = 0.82mh
L3 = 1.2mh

Resistors
R1 = 18 ohm
R2 = 33 ohm
R3 = 4.7 ohm
R4 = 27 ohm

I'm assuming that LSP1 and LSP3 are the + speaker leads, and LSP2 and LSP4 are the negative speaker leads. Is this correct?

Also, it's been mentioned that certain parts can be exchanged for different values to change the sound. Which parts are they, and should I buy different values to experiment?

Finally, can an L-Pad be installed in this design, and do you recommend for or against it?

Thanks, and sorry for all the questions... :)

Capacitors:
2,2uF
6,8uF

You won't find 3,6mH inductor - buy 3,9mH and than unwind few turns of the wire (it will work with 3,9mH, but it will be a bit lifeless).

The rest is OK.
LSP's - correct.
You can vary the value of 4,7Ohm resistor to get more or less hifreq energy - buy additional 3,3 3,9 6,8 Ohm resistors. Or you can instead of the 4R7 resistor install 8R section of L-pad, but I would go with resistors.

:2thumbsup:

Wow this certainly is something to make a guy wonder about these drivers now.. For a pair of loudspeakers that are touted by many to be the best of their kind ever made, it really shouldn't be this hard, especially considering the significant price tag!

What gives? It really shouldn't have to be rocket science should it?

I've been sitting on the fence for awhile now waiting and trying to find out as much info as I can, now I'm happy to not have ordered as of yet..

Hope all this effort, money and frustration works out for you in he end!!

:)

Hi :waver:,

I just finished soldering Jeff Markwart's "Simplified 604-8H EQ Crossover" for my 604K in 620 cabinets (with L-pad). In my humble opinion a significant lift compared to the stock crossover. Much less shoutiness (possible to fine-tune with L-pad). I used Solo Inductors and Vampire Hook-Up wire but substituted the Hovland caps for Russian NOS paper in oil capacitors including the teflon FT3s for the high-pass part. To help low end I also use a powered sub (mono). Very satisfied.

Naimare

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Originally Posted by DaveCan

It really shouldn't have to be rocket science should it?

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I haven't measured a pair, but I tend to think the drivers are awesome, though I'd echo others' wishes for a larger horn; what people are really moaning about are the crossovers -- which can be awfully difficult. Designing a crossover that everybody will be happy with is impossible.

Despite a poor first impression, I still comtemplate picking up a pair from time to time.

Regards,
John

Hello all.... feel it's time to chime in with my $0.02 worth.....

I have designed many crossovers variants for the 605A, 604E & 604-8K. The 605A and 604E's were basically stock builds, 8K's were a 1983 16X chassis re-worked by GPA into a 8K configuration. They did a great job BTW!

With these high performance... high efficiency duplexes very slight crossover differences can make a HUGE difference in sonic out come. Do not have the time to discuss my beliefs on why that is now. Maybe a later topic.

I have noticed a couple of things of importance...

How the woofer is loaded ... type - size of enclosure... or... no traditional enclosure as in OB or Cardioid is the first thing that has to be settled... and fine tuned BEFORE serious crossover work can be undertaken. The bass qualities of say the 605 are very different if operated in a sealed box, IB or vented.... let alone OB or Cardioid... and this is significant with the woofer cone having to contribute up to about 2 KHz.

And.. second... it really helps to have a first class reference during crossover fine tuning. That is a reference speaker that you find to be to your personal liking. It is so easy to end up chasing sonic artifacts too far before realizing where you're going is not helpful. Taking measurements helps during the tweaking (voicing process if you will) but measurements alone usually will not get you to where you need to go.

I am fortunate in that I have tons of parts... inductors, capacitors, audio grade resistors, L pads and so on as well as various sized test boxes and baffles. Plus working with crossovers for 50 years doesn't hurt either. With all that said... getting the duplex's to sing is not an easy task. But... when you get there... there are few systems that can do what these duplex's can do. Which is why they are... for many of us, worth the trouble... effort.

I have worked with Jeff Markwart's designs and they are very sound... no pun intended. Way closer than most other designs I have seen published and tried. Including nearly all Altec developed designs. His understanding the raw characteristics of these drivers and using frequency spreads to help maintain phase through the band pass is key to solving the shout and other problems so many comment on. These are Thoroughbred drivers that demand special care and attention... but like a Thoroughbred can deliver like no other.

An example of the effectiveness of Jeff's 605A work (with some personal modifications for OB operation in a small room) can be found here:

lone star audio fest 2008 and here Lone Star Audio Fest 2008 - Event Reports - Dagogo

Many were amazed by the dynamic yet smooth presentation as well as excellent imaging this set up provided. Plus the ability to play at live levels without a hint of strain.

It can be done.

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Originally Posted by DaveCan

Wow this certainly is something to make a guy wonder about these drivers now.. For a pair of loudspeakers that are touted by many to be the best of their kind ever made, it really shouldn't be this hard, especially considering the significant price tag!

What gives? It really shouldn't have to be rocket science should it?

I've been sitting on the fence for awhile now waiting and trying to find out as much info as I can, now I'm happy to not have ordered as of yet..

Hope all this effort, money and frustration works out for you in he end!!

:)

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This is what I was starting to think it shouldn't be this hard.The only differance that I can tell and from talking with Bill is between the 604-8H II and the 604-8H III is that the III is supposed to extend alittle higher to 22 khz were the II reaches 20 khz.

They are both beautiful sets of drivers what has become quite obvious is the problem lies in the Crossovers for these Beauties.Once these issues can be worked out everyone I know or have spoke to couldn't be happier with them but man to get there WTF can be a bitch.But the final outcome of these drivers is WORTH THE EFFORT!!! And all the people I have talked to about this say at the end that they think they have arrived at the speaker they have been looking for,for good. :) So the rewards could be great, everyones preferance is differant and what the L-pads try to accomplish I think is to appease the masses to fine tune to everyones liking tone up or tone down.

I'm very interested in this thread as I'll be in the same boat maybe when I start to build new cabs for my 604's come this spring when it warms abit.I hope you can come to a quick resolution with this and don't give up on such a nice set of drivers,cabs,etc..

Seadweller may you have some "Great Luck" in the near future I HOPE !!! ;)

With all the great talent on this board you are in GREAT HANDS ~ GOOD LUCK !!! :2thumbsup:

Not to step on Seadweller's thread....

But I was thinking about connect an lpad to my GPA XO's to maybe find a sweet spot for my 604's...

Where would I place it?

Thanks,


-chris

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Originally Posted by Seadweller

Thanks GM.

........or even more likely, that the excessive midrange energy is masking it.

Honestly, if worse comes to worse, I could add a subwoofer to the system..........

........there is a range of frequencies that when a voice or instrument fall in that range, the beaming is like the phaser on the Enterprise.

Actually, for my own curiosity, would a passive radiator mounted in the bottom of the cabinet be an option? Or how about an active driver?

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You're welcome!

Which can be caused by a leaky cab rolling off all the bass.........

Well, I'm not there and for sure if there's a hump in the horn's response it can sure sound this way, but I find it hard to believe that this would occur with JM's XO assuming it has the adjustable pots to dial it in.

PRs have a compliance measured in the hundreds of liters, so they can only be vertically oriented, same as most Altec drivers, including the 416.

Adding a driver to a given cab effectively reduces the air mass spring each driver feels, so F3 goes up and Fb normally must go down to keep it from sounding 'boomy'. In short, it will have ~ a half octave less bass response.

GM

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Originally Posted by oface1

But I was thinking about connect an lpad to my GPA XO's to maybe find a sweet spot for my 604's...

Where would I place it?

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Got an accurate schematic?

GM

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Originally Posted by RonSSS

I was going to mention that about the stuffing. One can change the amount to change the finger rap on the cone from a thump to more of a whack....you have to try it.

A port firing down into the floor, especially hardwod makes no sense to me.. In a box that large, firing forward makes more sense.

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Right, one way to ~critically damp the cab by ear.

Why? Acoustically there's no difference until the down firing port is close enough to the floor or other boundary to mass load it to a lower Fb except when there's padded carpet underneath, then it absorbs any out of BW noise that it may be pumping out.

GM

This GPA 604 project had to deal with 'shoutiness'. It might be helpful.

6moons audio reviews: Steph?n's Altec 604 Dream Speaker

Cheers, Marshall.

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Originally Posted by mah

This GPA 604 project had to deal with 'shoutiness'. It might be helpful.

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Thanks mah...I actually traded several e-mail's with Stephaen, and he was kind enough to give me some advice, and send me the schematic of the 4th order crossover he currently uses...I had it built and tried it, but the sound is very dark and subdued...In all fairness, he warned me this would be the case...

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Originally Posted by GM

You're welcome!

Which can be caused by a leaky cab rolling off all the bass.........

GM

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The only possible leaks would be at the removable XO panel on the back of the speaker, or the driver itself...I do not have a gasket behind the driver, although I've seen cork gasket sets on eBay...

The driver and XO panel fit extremely tight to the cabinet, and the XO panel is actually secured by 10 screws...Could a very minute amount of leakage in these areas impact bass response to this degree?

Are you saying there's no sealant between the driver or XO and mounting surface? If so, I'd be very surprised if there's no leaks and based on your various observations WRT vent lengths, various XO woes, etc., it would explain them all except maybe some portion of the high intensity beaming which can be dealt with by adding a foam insert, but that comes under the heading of fine tuning.

AFA how big a leak it takes to basically delete the vast majority of box loading it's as little as air leakage around the mounting bolts and T-nut threads, but an air leak around the driver ~completely negates any box loading.

GM

Hi gang. In my absence, I had to catch up on 11 pages of this subject.
The last time I saw a project go this bad, the problem ended up being the CD player.
Didn't you say it's 20 years old? Is it your only source?
I've heard them shout when they fall out of specs.







:)

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Originally Posted by Art J.

Hi gang. In my absence, I had to catch up on 11 pages of this subject.
The last time I saw a project go this bad, the problem ended up being the CD player.
Didn't you say it's 20 years old? Is it your only source?
I've heard them shout when they fall out of specs.

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Funny you mention this, as it is my only source...This was on my list of suspects, but quite frankly, I never tried another source, because every time I inquired, folks said that it would not be possible for the CD player, being digital, to impart its own sound...

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Originally Posted by GM

Are you saying there's no sealant between the driver or XO and mounting surface?

AFA how big a leak it takes to basically delete the vast majority of box loading it's as little as air leakage around the mounting bolts and T-nut threads, but an air leak around the driver ~completely negates any box loading.

GM

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Thanks GM....No, there is no sealant around the XO panel or the driver....The XO panel and cabinet mating surface were milled so they basically seal, but I guess without a gasket of some sort, it would not be completely air-tight....I'm sure there's leakage around the driver as well, but it never occured to me that such a minimal amount of leakage could impact the loading of the cabinet to this degree, particularly with such a big cabinet, and large driver...

If a small amount of leakage can impact things so drastically, I think my initial steps at this point will be to install a gasket in the XO panel, and a gasket behind the driver to make sure the cabinet is sound...Then I'll get an amplifier and different CD player to rule out the obvious...

From there, I guess it's back to the XO...:)

EDIT: I may have to correct myself, but I'm on my way to the airport, so I'll have to validate this weekend...It's been a while since I installed the drivers, but something tells me that GPA shipped a neoprene-type gasket set with them...I'll pull the driver and see if they're installed...

OK - time to jump in again.

1. Digital electronics, especially older digital electronics, does, indeed, impart it's own "contribution" to the sound of the audio passing through it. It just can't help it - unlike tube-type systems, which respond in what I call a "harmonic" manner (even-order harmonics), digital audio has more odd-order harmonics in it which gets added into the mix and does (believe me) sound harsh.

This is why I recommended originally getting a recording of music that you are familiar with that was recorded LIVE - not mixed down in a studio (many of them are all-digital now) - and see if the problem goes away. While I was thinking about the recording itself, it could be your problem lies in the playback equipment, at least in part.

2. As far as the GPA 604's go, I have the following to say:

A. They are excellent drivers that measure extremely well. I have seen the TEF measurements and they are amazing - the best of any of the 604's ever made. The "shoutiness" that some folks get with them would show up in the TEF response curves and waterfall plots if this problem was inherent to the speakers themselves. It's just not there. Period.

B. The stock crossover from GPA was developed by Jerry Hubbard, who was HEad of Acoustic Research at Altec for many years. His designs are straightforward, simple, and effective. He does extensive real-time testing to assure they are correct. That said, one also has to keep in mind that his design was done with these products installed in a correctly designed and built enclosure - as several have pointed out here in this discussion, when the enclosure leaks, is the wrong size, isn't properly damped, is damped too much, if the crossover is changed, etc., all these things can alter the sound coming out of the speaker, and the 604 will pain the audio picture of those changes, "warts and all."

C. With regard to the man who was disappointed in the GPA 604's at the Colorado audio show - having not attended (I will this year), I can't comment on the system that was used there. That said, I can tell you that when I demonstrated the 604-8H-II's in Stonehenge V-type boxes at the Great Plains Audio Fest in Tulsa a few years ago, using the stock crossovers, no one heard what you're talking about or complained of listener fatigue. The only person who did complain was Earl Geddes, who was yelling at me about the size of the horn being too small, but he was mad because his new, amoeba-shaped speaker was getting bested by the 604's, according to the comments of the attendees.

I was using a newer CD player and a vintage Altec 714A Receiaver (30-watts) from 1964 to power them - no eq, no L-pads. Just straight. We also auditioned some tube amps and other recordings, all of which, except one of the recordings, were well received.

D. My suggestion is:

1) Build one Stonehenge V-type enclosure with proper bracing, properly sealed, properly tuned, and properly damped. If you need drawings, dimensions, etc., I have the hand-drawn ones I made for my cabinet man to use when he built them for me. They're not pretty, but the design works.

2) Install the stock GPA crossover & connect the speaker to the amplifier.

3) Set your amplifier eq settings (aka tone controls), if it has any, to flat.

4) Find a live recording (we used to call it direct-to-disc) of music that you are familiar with, or, perhaps, totally unfamiliar with. Maybe more than one - some with vocals, some without.

5) Borrow a high-end playback unit from someone, if need be, for playback. Do not use the one you've been using. The newer digital units have been "tamed" somewhat.

6). Take the speaker outside and listen to it as it sits on the grass with no reflective surface nearby.

7) Listen to it. See what happens. Make specific notes as to what you hear on what recordings.

8) Now take it inside and repeat #7.

Let us know what happens.

Ultimately, my guess is you'll find that you've been chasing rabbits - the real problem is, I think, that you've been trying to treat symptoms that have been caused by symptoms, rather than the real problem, adding "fix" upon "fix" upon "fix", and muddying the waters even further.

As Chief Engineer Montgomery Scott, after assisting Admiral Kirk In StarTrek III in stealing the Enterprise from Spacedock and the Excelsior was unable to pursue, when handing the computer chips from the Exclesior's TransWarp Drive computer to Dr. McCoy, he said, "The more they overcheck the plumbing, the easier it is to stop up the drain."

These speakers are excellent performers - the problem is not in them. It is elsewhere.

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Originally Posted by Todd W. White

A. They are excellent drivers that measure extremely well. I have seen the TEF measurements and they are amazing - the best of any of the 604's ever made. The "shoutiness" that some folks get with them would show up in the TEF response curves and waterfall plots if this problem was inherent to the speakers themselves. It's just not there. Period.

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Hi Todd,

Could you share the off-axis measurements? The on-axis TEF measurements I've seen are indeed impressive, but "shoutiness" is sometimes apparent only when looking at the power response/ range of on- and off-axis measurements.

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Originally Posted by Todd W. White

C. With regard to the man who was disappointed in the GPA 604's at the Colorado audio show - having not attended (I will this year), I can't comment on the system that was used there. That said, I can tell you that when I demonstrated the 604-8H-II's in Stonehenge V-type boxes at the Great Plains Audio Fest in Tulsa a few years ago, using the stock crossovers, no one heard what you're talking about or complained of listener fatigue.

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I heard what I heard. And, I'll suggest that my impressions seem to echo some of the feedback received at Tulsa, as seen here: PIC'S OF ICONIC'S DEMO ROOM @ GREAT PLAINS AUDIOFEST IN TULSA! and further discussed by GM and joyspring later in the thread.

I have no doubt that the 604s are excellent performers, and that I am in the miniscule minority that is perhaps hyper-sensitive to these kinds of issues. But that doesn't mean I'm nuts, either.

My apolgies for taking the thread so far afield; I'll restrain any future comments to only address Seadweller's journey.

Regards,
John

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Originally Posted by Seadweller

Funny you mention this, as it is my only source...This was on my list of suspects, but quite frankly, I never tried another source, because every time I inquired, folks said that it would not be possible for the CD player, being digital, to impart its own sound...

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Oh boy, CD players sound nasty when there is a problem in the output stage.
Or they quit all together. It could have nothing to do with the digital end of it.
I hate to sound 101ish on a Pro board but all equipment involved with such a project
should be proven and trusted ahead of time. Sorry...................






:)

I don't have the off-axis response curves here. That said, these weren't designed to be listened to very far off-axis, either.

Thanks for the reminder of the earlier discussion - my recollector isn't always what it used to be...

That said, I do recall, now that I think about it, and re-reading the posts, there were some problems with room acoustics, which most folks acknowledged. There were also some problems with one of the recordings, but, if memory serves, I later found that to be in the recording, no matter what speakers I played through (even my Model 19's, Model 6's, and others I have at home).

Room acoustics at the Tulsa show were, indeed, a problem - hard surfaces, lots of reflections, etc., not suited for listening. Not even well suited as a living room, IMO...

Also, I do agree - I think there may be some who are, as you mention, hyper-sensitive listeners. For example, for many years when stores were using those ultra-sonic burglar alarms, I had to have them turn them off, or I couldn't go into the store - it killed my ears....just killed them. The people in the stores said they couldn't hear it, but admitted that a few of their customers did complain...

So, there are some for which nothing, other than a Shure VocalMaster Sound Column would sound good (terribly limited bandwidth)...as long as their amplifier had the special "Tone" knob like the VM amp did...

Given all that's been said, I still believe that if he will go back and do what I said in my most recent post, he would find a different result. It would be impossible for the 604 - in all it's variants - to be such a widely acclaimed speaker for so many years if there wasn't a good bit of "good" performance possible with them...

Quote:

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Originally Posted by Art J.

I hate to sound 101ish on a Pro board but all equipment involved with such a project
should be proven and trusted ahead of time. Sorry...................
:)

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No apology necessary! The CD player worked/sounded pefectly fine with my prior pair of speakers, so I never gave it a second thought...We'll find out in short order if it was the weak link however...

Quote:

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Originally Posted by Todd W. White

...and they made Altec use the DH-1A HF driver magnet, if memory serves, for the 604 and the 515...

The result in the 604-8K was the midband got too much energy.

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So... (any takers) ...would an impedance sweep (a la my 'woofer tester 3') reveal them to be one vs the other? ...and I'd be checking the HF, right?

Perhaps the obvious answer would be: 'only if you have the verified 604-8k-(insert geographic subtype here) results to compare it to'. ?

Maybe not - it could be the LF cone is part of the equation, too. Remember - the crossover is around 1,600 Hz, so the cone is involved up into the midband, even though the horn starts kicking in quite a bit below that...

Quote:

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Originally Posted by Seadweller

No apology necessary! The CD player worked/sounded pefectly fine with my prior pair of speakers, so I never gave it a second thought...We'll find out in short order if it was the weak link however...

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I like finding CD players at Pawn Shops. They don't sell well in a world of i-pods
and i-phones. They go cheap. I buy the types that have a headphone jack and a
digital output so I can reference them to an external DAC and headphones. You
can score a top model if your lucky.




:)

One of the most famous recording studio on the East Coast uses Big red in the main control room of studio A. And in the recording studio. AVATAR STUDIOS

The CTV Olympic song was recorded there.

NIKKI YANOFSKY

http://www.hostboard.com/forums/hbmc...2010/02/18.jpg

Avatar is using GPA-made 604-8H-II's:

http://www.greatplainsaudio.com/Avatar_03.jpg

The Big Reds are in the control room of their main recording room. There are numerous studios that still have them but like in most studios these days they are rarely if ever used, Genelec's and other small powered monitors rule the day. A sore spot for me.

Dave

Last resort?

Hyperacusis/Recruitment

Marshall.