my new 604 cabinets I'm building.

Well it sounds like you don't need any help at all !! Great Job BTW ! :Thumbs up:

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Originally Posted by Altec Best

Well it sounds like you don't need any help at all !! Great Job BTW ! :Thumbs up:

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Thank's AB, I really don't have a clue what I'm doing just rehashing all the info I read on the net. Eventually it kinda makes sense and if I get enough of the same opinion I feel like I can pretty much trust that it's true. :) BTW that Martin J king stuff goes over my head like the space station. I don't think I would be able to understand it if Martin himself was telling it to me himself one word at a time.

Quote:

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Originally Posted by Altec Best

You need to be exact with the numbers to be accurate with the results. I think you said 12.44 cubic feet in an earlier post.But from that .jpg looks like you put in 12 cubic ft.IIRC you have 2 different 604's that you had GPA recone correct ? If so what did they recone them as 604 g,h, ???

He came up with the 41 Hz from your port dimensions I think.You may need to add length to the port to lower it some. 25-30 Hz port tuning is more in line for HiFi/HT I think GM was getting at.

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I do have 2 different 604's a"C" and an "E" GPA did not recone them as they said they didn't need it and I would be better off leaving them alone so I did.

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Originally Posted by cradeldorf

I just don't know how he calculated the 41 hz box tuning frequency? I just used this online one and came up with 29.4836? Not sure If I'm doing it right, but it looks right. Did you read the link I posted in post #32 by
John L. Murphy Physicist/Audio Engineer?

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Easy, I used well-proven math for vented alignments, not the formula for a heavily stuffed sealed alignment as this calculator does.

Yes, I?m familiar with it; the basslist threads I was usually a part of prompted many of his tech topics. For the record though, his generalizations are just that, a ?vents for dummies? tutorial since at the time few of us on the forums that understood most/all of the ramifications didn?t want to part with our hard won knowledge just so folks could go off and use it for profit.

Anyway, if anyone is serious about DIY speaker design as a hobby or business, I strongly recommend you use MJK?s MathCad software [please pay the business fee if applicable] as it?s the most accurate I?ve ever used and not nearly as hard to learn in depth as AkAbak.

FWIW, the math I?ve used for decades to calculate vents match right up with his calculations when a lightly damped golden or acoustic ratio cab is simmed and his MLTL vent calculations line up with the measured results of some of my old designs I still had final details of, so confident enough that any other alignments would be too, though if I needed it to be tuned to Fs I would cut the vent[s] too long and do the measurements to fine tune it.

GM

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Originally Posted by VolvoHeretic

I'm still quite confused on this, especially after reading my Radio Shack "Advanced Speaker Design" book three times and doing all of the math long hand. Isn't the only frequency coming out of the port the box/port resonance and at Fb the speaker is motionless and all of the air motion is in the port and in faze with the woofer? Doesn't aiming the port out the rear, bouncing off of the wall make it out of faze with the woofer? :)

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It?s a narrow pass-band of frequencies with its width [Q] being determined by the vent and system Q which in turn determines how ?locked up? the driver is at Fb. Consequently, it?s only in acoustic phase at Fb, rotating increasingly out of phase on either side as shown on an impedance or transfer function phase plot. This animation does an excellent job IMO of visualizing driver/vent interaction: Essay

This is addressed in JM?s tech note. Still, I?ve used rear and bottom firing to good effect and in many cases preferred bottom firing for MLTLs, using adjustable feet to fine tune vent loading.

GM

Quote:

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Originally Posted by GM

Easy, I used well-proven math for vented alignments, not the formula for a heavily stuffed sealed alignment as this calculator does.

Yes, I’m familiar with it; the basslist threads I was usually a part of prompted many of his tech topics. For the record though, his generalizations are just that, a ‘vents for dummies’ tutorial since at the time few of us on the forums that understood most/all of the ramifications didn’t want to part with our hard won knowledge just so folks could go off and use it for profit.

Anyway, if anyone is serious about DIY speaker design as a hobby or business, I strongly recommend you use MJK’s MathCad software [please pay the business fee if applicable] as it’s the most accurate I’ve ever used and not nearly as hard to learn in depth as AkAbak.

FWIW, the math I’ve used for decades to calculate vents match right up with his calculations when a lightly damped golden or acoustic ratio cab is simmed and his MLTL vent calculations line up with the measured results of some of my old designs I still had final details of, so confident enough that any other alignments would be too, though if I needed it to be tuned to Fs I would cut the vent[s] too long and do the measurements to fine tune it.

GM

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I love how you force us to learn, it kinda feels like your a professor and were your pupils. It truly is a good feeling and as my dad used to say nothing worth earning is free. I have the winIsd at home on my puter so I'll fire it up and see if I can remember from the last time I tried using it. As always Thanks Greg.

Wow--lots of great info for all of us to absorb here--thanks GM! I was about to put an SOS message on this thread (Save Our Speakers)! Much of this goes over my head but I'm going to do some reading and see if I can make (more) sense of at least some of it. Greg, I know this stuff is not always completely black and white, but do you think Cradeldorf is "better off" putting the port on the front or the back of his cabinets? Also, 65 square inches seems awfully big to me for a port size if he wants to get a "modern hi-fi" tuning for his cabs (as you alluded to)--any suggestions (even a ballpark suggestion?) as to what port dimensions may get him a nice low tuning--say closer to the tuning of the Model 19 cabinets?

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Originally Posted by cradeldorf

I'm mulling over filling all the voids between the braces with 2" egg crate foam. I hope the 2" is the total height of the foam plus the eggs and not just the foam itself.

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Originally Posted by Altec Best

I'm not sure foam is a good dampening material internally in the cabs.Good old Fiberglass insulation performs better IMO.YMMV

Maybe someone else could help out with this decision and chime in.I only ever use insulation.

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Anyone have any preferences/ideas that they'd like to share as far as this "egg crate" foam vs. more conventional insulation?

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Originally Posted by cradeldorf

I think you would be astonished at how much bass my as101's make Vott. they literally shake the fillings in my teeth. :; <---see one tooth fell out already. :D ......

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I'm not saying that the current tuning of your AS 101 cabs with regard to being used with 604's isn't resulting in enough bass. Quite the contrary, from this post and some of your other posts in other threads, I think the fact that those cabs were not tuned with 604's in mind may be giving you way too much mid-bass response which is throwing off the ratio of midrange to midbass to the "lowest" bass your speakers can produce and resulting in a "mess" (yes, I know, a very technical term) and the "shelf" that someone added in a failed attempt to implement DBR tuning may be reeking havoc with the tuning/sound quality as well in ways I can only imagine since I haven't heard them. Hopefully these new cabs, once tuned/ported/insulated/etc. "properly", will sound great!

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Originally Posted by cradeldorf

I think you would be astonished at how much bass my as101's make Vott.

I wish Greg hung out here more....

I think I'm gonna split the back board so I can just replace the bottom half with a different one with a different port size in it.

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Bass or mid-bass? Vintage tunings typically were mostly mid-bass, same as most prosound still are, not to mention most recorded music peters out quickly below ~40 Hz or higher in older recordings.

Regardless, without response measurements at the listening position [LP], need to know how much series resistance there is as well as room acoustics to zero in on what you?re hearing, so mostly a rhetorical question unless you have perfect pitch.

Circumstances has forced me into a ~ one [more like half] man ?crew? doing a whole property rehab on a shoestring budget, so at best probably won?t have much quality time for at least another year to spend much time on the forums, PMs, etc.. The rain has stalled me till probably tomorrow and should be doing indoor stuff, but you know how it is with hobbies??..

Good plan, I typically recommend a removable/gasketed vent panel to allow easy tuning changes. That, or use heavy cardboard or PVC pipe vents left extended enough to easily swap them out, using blu-tac or similar to temporarily seal them to the baffle.

GM

Quote:

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Originally Posted by cradeldorf

I'm mulling over filling all the voids between the braces with 2" egg crate foam. I hope the 2" is the total height of the foam plus the eggs and not just the foam itself.

I don't think I need dampening, That's only for small boxes that you want to make sound larger than they are. What I want is to break up the standing waves and keep the mid frequency waves from bounding all around the inside of the cabinet and coming out through the port or cone.

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I’m no fan of foam, but would only use open cell, otherwise the closed cell will reduce net Vb somewhat, but no clue how much. Also, it’s my understanding that it works best when spaced away from the walls, though don’t know how far, and any braces must be covered also; so hanging a full length ‘blanket’ of it diagonally across the cab *plus damping the inside of the top* seems the best solution overall.

Your cab’s internal dims falls within the acceptable room ratios, so I normally recommend using Altec’s, i.e. lining one wall, back and end opposite the vent with 1” acoustic fiberglass insulation or if polyfil stuffing [AKA damping] is preferred, starting with ~1.67x the fiberglass’s calculated lbs/ft^3 stuffing density and adjust more/less to ‘taste’. My SWAG is that this equates to a ~0.25 lbs/ft^3 polyfil stuffing density using MJK’s software.

GM

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Originally Posted by GM

I’m no fan of foam, but would only use open cell, otherwise the closed cell will reduce net Vb somewhat, but no clue how much. Also, it’s my understanding that it works best when spaced away from the walls, though don’t know how far, and any braces must be covered also; so hanging a full length ‘blanket’ of it diagonally across the cab seems the best solution overall.

Your cab’s internal dims falls within the acceptable room ratios, so I normally recommend using Altec’s, i.e. lining one wall, back and end opposite the vent with 1” acoustic fiberglass insulation or if polyfil stuffing [AKA damping] is preferred, starting with ~1.67x the fiberglass’s calculated lbs/ft^3 stuffing density and adjust more/less to ‘taste’. My SWAG is that this equates to a ~0.25 lbs/ft^3 polyfil stuffing density using MJK’s software.

GM

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Hmmm since you say that I'm picturing a half circle of foam starting on the left side against the baffle and then making a giant u shape to the back of the cab and back to the right side of the baffle. Or I could do some 1" thick 2 x 4 acousical ceiling tiles mounted to the braces. Unfortunately I spent my allotted cabbage on those EV speakers for this paycheck. If I didn't have the car insurance man with his hand out I'd have an additional $250 to spend this paycheck but I don't. Might be another 2 weeks till I have any spare cash unless my refinancing loan goes through soon.

Well, you could do it that way, though it's not what I meant. Visualize the top is off the cab, now lay a 'curtain' rod diagonally across two corners and hang a weighted floor length 'drape' from it...... In theory, my way won't damp quite as well, but then the object is to make a design that works well with minimal internal damping.

Acoustical ceiling tiles will reduce net Vb, but is a good way to both quell any eigenmodes and mass load the cab somewhat......

I see I forgot to include damping the inside of the top also if doing the 'blanket'......

Glad you have a paycheck, they're getting scarce in my locale......

GM

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Originally Posted by GM

Well, you could do it that way, though it's not what I meant. Visualize the top is off the cab, now lay a 'curtain' rod diagonally across two corners and hang a weighted floor length 'drape' from it...... In theory, my way won't damp quite as well, but then the object is to make a design that works well with minimal internal damping.

Acoustical ceiling tiles will reduce net Vb, but is a good way to both quell any eigenmodes and mass load the cab somewhat......

I see I forgot to include damping the inside of the top also if doing the 'blanket'......

Glad you have a paycheck, they're getting scarce in my locale......

GM

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Thank's Greg, I knew what you were saying....I thought about it some more and thought maybe an upside down U might be more practical so the wave could reach the port on the back panel. It's not like it's permanent, lots of different things I can try.
Paychecks are getting scarecer and smaller here too. : ( Those rapist bastards. >: (

Ok this is where I'm at with WinIsd.....Is there a way to change the white line to the shape I want? or is this just what I'm gonna get from my cabinet?

EDIT: If I change the box freq. I got the line to look more like I think it's supposed to.
The first pic and the last pic are the new 37.5 box freq. the second is the first one the program spit out 27.11 Is changing the box frequency what I'm supposed to do to work the program correctly?
Do I want to keep the white line between the 0 and -3db line for as long as I can without it going outside of either one? because if so then 37.5 was the magic number.

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Originally Posted by cradeldorf

I love how you force us to learn, it kinda feels like your a professor and were your pupils. It truly is a good feeling and as my dad used to say nothing worth earning is free. I have the winIsd at home on my puter so I'll fire it up and see if I can remember from the last time I tried using it. As always Thanks Greg.

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Quote:

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Originally Posted by cradeldorf

That's what the Altec bulletin suggested for the 604? I haven't cut the ports yet, if you got a better suggestion.

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You?re welcome!

Hmm, they say you can?t force a willing victim, ;) but yeah, the longer I?ve been on-line the more I?ve made it my desire to expose folks to enough information for them to make a relatively informed decision about something that either is counterintuitive and/or has been subverted by the ?misinformation? distribution types, be they amateur or professional to [rightly or wrongly depending on your POV] protect their intellectual property, or worse, just plain mean spirited.

Please use the Pro alpha version at least for now as it has proven more accurate [assuming there?s been no recent updates to the basic version] and I haven?t taken the time to scope out /use V7.

This is a ?60s era modified version of a chart that dates back at least to the early ?50s when according to a RCA recording/broadcasting studio and control room design specs manual, the reference for a ?full range? studio or cinema sound mixing monitor was a 50-11,000 cps [Hz] ~flat BW; so a ~40 Hz tuning in a large cab driven with at least this low an Fs driver was a SOTA HIFI alignment for its time and a 75-7,000 cps response being considered adequate for orchestra and vocal groups, ergo up to a ~65 Hz alignment was what most consumer sound system designs were based on.

This is borne out if you do the math, as cone resonance increases, so does the chart?s recommended tuning [no high Q drivers tuned below Fs as T/S dictates] and by 65 Hz its tuning is ~65 Hz since back then the drivers couldn?t handle much power near its Fs due to having little usable linear cone excursion and presented a poor electrical power transfer to the high output impedance amps of the day.

Not too surprisingly, the HF design limit has been extended in step with recording advances since it?s not expensive to do and doesn?t increase the speaker?s bulk like lowering its useful LF BW does for a given system efficiency, so sadly, a ~40 Hz alignment still covers most mainstream recordings, but for SOTA HIFI it needs to extend to cover a few pipe organ symphonic recording?s 16 Hz or at least 20 Hz for a movie soundtrack and/or at least a concert grand piano?s 27.5 Hz lowest note.

With this in mind, the highest measured Fs duplexes need a separate sub system just to cover the piano and the lowest is marginal at best if not in an I.B. sealed alignment and due to their strong [low Qt], low linear excursion [Xmax] motors they typically need EQ plus some room gain to get them ~flat to this low a frequency at the listening position [LP].

So between you having mismatched drivers and not knowing their actual Fs, sealed + EQ may be your best choice overall.

For experimenting with vented though, you can easily choose a starting point using any program that ~accurately calculates the vent?s air speed with changing electrical power and choose a vent area that doesn?t exceed ~5 % vent mach [~17.2 m/s (56.5 ft/s)], then at least with WinISD Pro, select ?flanged both ends? to get the closest match-up to most of my real world results or use the ?two free ends? setting to probably ensure enough to cut off if doing measured fine tuning.

GM

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Originally Posted by GM

You?re welcome!

Hmm, they say you can?t force a willing victim, ;) but yeah, the longer I?ve been on-line the more I?ve made it my desire to expose folks to enough information for them to make a relatively informed decision about something that either is counterintuitive and/or has been subverted by the ?misinformation? distribution types, be they amateur or professional to [rightly or wrongly depending on your POV] protect their intellectual property, or worse, just plain mean spirited.

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+1 This is what puts you a cut above IMO ! Always kind and generous with your time for some of us Folk's who are just looking to build a once in a lifteime "Stellar Speaker Project" ! :cool2:

I agree, Greg you are the best defense in an all learning community. I'd hug you but your too far away...and being that your a dude...yeah it'd be kinda weird. I'll take your knowledge and use it to the best of my ability for my own personal use.
Thanks Bro.

They're in the new cabs, Even though I don't have backs on them because I'm broke again I'm totally liking what I'm hearing. I have them shoved up against the wall but because there's a base molding along the floor they're actually about a half inch off the wall. The bass is very deep and strong. Just the way I like it. :) and it's like they have mid-range now before it was totally lacking compared to the lows and highs. I do have some scrap wood I could make some backs out of but they would be pieced together.

Patience. Do it right when you can. Enjoy in the meantime.

Thank's Mah, well it's about 6 am and I'm getting tired. I shot a little video of them with some zoolander on. My camera doesn't really capture the sound as good as it is live but it's the best I got. Someday they'll have backs on em. :)

Zoolander on Altec 604&#39;s with new 12Ft cab&#39;s.wmv - YouTube

That's great you already hear that big of an improvement with the new cabs pushed up against the wall/even without the backs on them! Great Zoolander clip by the way (one of my all time favorite Ben Stiller movies). Did anyone see Ben Stiller host Saturday Night Live last Saturday Night? He "revived" the Zoolander character for the first time in over 10 years (first time I know of since the film was released in 2001). It was hilarious and I guess the closest thing the world will ever see to a Zoolander sequel. Here's the footage (Stiller makes his entrance just before the three minute mark).http://www.youtube.com/watch?v=-9M0igx7CjQ

Stiller also revived his Bruce Springsteen imitation on the Saturday Night Live episode last Saturday for the first time (I know of) in 20 years (since the TV series "The Ben Stiller Show" in 1991). Here's that footage http://www.youtube.com/watch?v=8accBfnvilQ
HILARIOUS CLIPS--this guy is too damn funny.

Roll up some towels and wedge between the back edges and wall. And get some better music samples! You're auditioning those beauties to Wham!?

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Originally Posted by VolvoHeretic

You're auditioning those beauties to Wham!?

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:Can't belive it: I think I would have to go with MFSL Dark Side of the Moon or MFSL 1812 Overture ! That's always my test LP's :Nodding:

Yeah--WHAM is about as lame as you can get musically! I think he also picked that clip for the great comedy and the sound of the explosion (in his defense) not just for the music. :Filmstrip:

Cradeldorf--crank up one of those great music CD's or DVD's you have in your collection! :Note:
That towel idea is an interesting suggestion (temporarily)......

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Originally Posted by Altec Best

:Can't belive it: I think I would have to go with MFSL Dark Side of the Moon ! :tongue2:

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I know Cradeldorf has some great FLOYD in his collection! (here's a FLOYD clip with his "aborted" open baffle design that comes up on youtube when you view his current clip of his new 604 cabs) http://www.youtube.com/watch?v=Kf0-CqIH91Q&feature=related

AHHHHGGGHHHH Dammit I knew I should have deleted that VID!!!!!!! LOL Shoot I was hoping you guys wouldn't ever see it. But it does prove one thing, you can practically have any goofball idea you want with Altecs and they'll still sound good. :)

Vott I can honestly say these cabs make the Heathkits sound like an 80's sparkomatic car stereo!!! they are smoother than cognac!!! And that stupid camera of mine really does no justice to the actual sound that I'm hearing in house. it's crazy delicious!!!! I'll shoot some floyd on them and get it up......the stupid wind is like a constant 50 MPH outside today....friggin driving me nuts. Now I gotta go watch those Saturday night live clips you posted they sound like some funny stuff. :D OMG!!! he should have done a Ted Nugent one too when he had that chin spinach on!!! LOL

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Originally Posted by cradeldorf

AHHHHGGGHHHH Dammit I knew I should have deleted this!!!!!!! LOL Shoot I was hoping you guys wouldn't ever see this.

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I think you also posted some photos of them here in an earlier thread. Anyways, you can still get hours of enjoyment out of those "aborted" cabinets now that you've removed your 604's from them. Just put in a dartboard where the 604's were! ;)

Quote:

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Originally Posted by cradeldorf

Vott I can honestly say these cabs make the Heathkits sound like an 80's sparkomatic car stereo!!! they are smoother than cognac!!! And that stupid camera of mine really does no justice to the actual sound that I'm hearing in house. it's crazy delicious!!!!

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That's fantastic news. It's always an amazing feeling when you "hit paydirt" on a project like this (especially after multiple cabinet attempts and the mismatch with the Heathkit cabs). I had a feeling from your description of the sound that those modified Heathkit cabinets were never appropriate/suitable for your 604's.....

Quote:

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Originally Posted by cradeldorf

Vott I can honestly say these cabs make the Heathkits sound like an 80's sparkomatic car stereo!!! they are smoother than cognac!!! ......the stupid wind is like a constant 50 MPH outside today

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Well when you get help from one of the best (GM) you can expect awesome results ! Yeah it's pretty windy here too !

Maybe I'll shove those EV's in them and dump them on craigslist.

Quote:

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Originally Posted by Altec Best

Well when you get help from one of the best (GM) you can expect awesome results ! Yeah it's pretty windy here too !

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Greg is Da Man!!!! Him and OldGuy said go big and they were 100% right!!! I actually think I'm shaking because they sound so good.

Quote:

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Originally Posted by Altec Best

Well when you get help from one of the best (GM) you can expect awesome results ! Yeah it's pretty windy here too !

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Yeah, we really are incredibly fortunate to have GM's expertise on this forum. He's given me invaluable assistance on multiple occasions..... We're also really fortunate to have this forum at all thanks to Todd. I've learned so much here in the almost three years I've been here. Lots of very knowledgeable people with a real passion for great speakers and music who have a very helping nature.....

Quote:

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Originally Posted by cradeldorf

Now I gotta go watch those Saturday night live clips you posted they sound like some funny stuff. :D OMG!!! he should have done a Ted Nugent one too when he had that chin spinach on!!! LOL

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I was literally laughing out loud at those clips. Zoolander gets the word "tourists" confused with the word "terrorists" for one....

Quote:

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Originally Posted by voice of the theater

That's fantastic news. It's always an amazing feeling when you "hit paydirt" on a project like this (especially after multiple cabinet attempts and the mismatch with the Heathkit cabs). I had a feeling from your description of the sound that those modified Heathkit cabinets were never appropriate/suitable for your 604's.....

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Yes I can totally tell a huge difference, before when I'd put on a Married with children to lisen to while I sleep I would have to turn it up so I could hear what they were saying. But when the theme music was playing it was wayy louder. Last night the theme music and their voices during the show were all the same level. so much nicer now.

Just shot two nice pink Floyd clips. Should be up in a couple hours. yes it takes me that long. : /

I see that you kids need help picking out your music, try these, my favorites :) ;
Weather Report - Nubian Sundance (Audio) (Mysterious Traveller) 1974 - YouTube
http://www.youtube.com/watch?v=xt91JJbyXfU
Return to Forever - Duel of the Jester & the Tyrant (Romantic Warrior) - YouTube
Mahavishnu Orchestra - Lila&#39;s Dance - YouTube
VOLVOHERETIC&#39;s Channel - YouTube

Ok, this time I uploaded the .Mov video straight from the camera to youtube instead of doing all the converting and crap. I think it sounds way better. Enjoy. : )

Pink Floyd on Altec 604&#39;s with 12CuFt Cabs.MOV - YouTube

Quote:

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Originally Posted by VolvoHeretic

I see that you kids need help picking out your music, try these, my favorites :) ;
Weather Report - Nubian Sundance (Audio) (Mysterious Traveller) 1974 - YouTube
Weather Report
Return to Forever - Duel of the Jester & the Tyrant (Romantic Warrior) - YouTube
Mahavishnu Orchestra - Lila&#39;s Dance - YouTube
VOLVOHERETIC&#39;s Channel - YouTube

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Wow, I've never heard of any of those. I'll check em out though buddy. I gotta head out for the night.

Quote:

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Originally Posted by VolvoHeretic

Roll up some towels and wedge between the back edges and wall.

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FWIW, doing a quick calculation......... hard up against a 1/2" baseboard, it appears to have a ~68.25"^2 area vent and due to wall loading, my swag is a several inch long effective vent, so ignoring some strong reflections off the wall back to the driver that's bound to be audibly modulating them in the lower mids similar to what one gets with an Onken alignment [if he hasn't installed any damping 'blanket' discussed earlier], I figure they're tuned around 34-36 Hz like one too.

Ideally though, a lower tuning is desirable, so experimenting with some towels or similar to reduce the vent area and damping the wall if need be sounds like a good plan to me.

GM