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Old 13th June 2014, 10:41 AM   #1
SNR is offline SNR  Canada
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Default Fun with 604E

Hello, I would like to build boxes for my Duplex.

I have come across various designs on the net. I might build it similar to the 620 cabinet or larger.
Space will not be an issue with these cabinets.

I have read that these speakers can be used in around 20 cu foot cabinets, although 5-9 cu foot is more typical.

Right now they are in 5 cu foot boxes which obviously do not sound flat.

The point of me buying 15" 100 db speakers is to get good sound without any EQ, even if this means having the equivalent of two refrigerators in my listening room.

So I guess my first question is how big can I go to improve bass without compromising the glorious sound of these bad boys?

Second question, actually more opinion, does anyone have a prefereence in sound between the typical vented box vs MLTL with this driver?

I tried my hand at WinISD, but the driver does not appear in the database, I was unsuccessful at entering the data manually. I assume the documented T/S for the 604E would get me in the ballpark without having to measure my set, although I do not object to that.

Also I did join the Altec Users, but the website is messed up and I am only half registered lol. There appears to be a lot of technical problems there. Too bad, it's a good little site otherwise.
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Old 13th June 2014, 04:32 PM   #2
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Great to see you want to get the most out of this wonderful coax! Box alignment and crossover are the obvious keys to your project.

First is to get an accurate measure of the woofers T/S values. Have you measured them?

I also assume you are aware of Jeff Markwarts interesting site about phase correct crossover solutions. Jeff Markwart's Corner - Phase Corrected Crossovers
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Old 13th June 2014, 05:32 PM   #3
GM is offline GM  United States
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Greets!

Well, if you research me [GM, GPM, among others] you’ll find my preference has been Harry Olson’s late ‘40s tall reflex [vented tower, column, MLTL] alignment since I was exposed to it in the ‘60s .

The largest cabs I recommend for < ~ 0.4 Qts drivers are typically Vb = Vas, Fb = Fs, so for the 604E, the largest MLTL can be up to ~27.5 ft^3, though the largest actually built to my specs IIRC was 17.64 ft^3 net/tuned individually to each driver’s Fs [< 30 Hz] by a professional horn blower in NYC and set up in a relatively tiny room/near-field listening app [home recording studio monitors? Can’t remember now].

Driven with a matching impedance SET, he was a ‘happy camper’, with solid bass down to Fs, but this was well over a decade ago now, so no clue if they stood the test of time.

Specs have varied quite a bit over the decades of re-coning, so considering how far out of spec some of GPA’s re-cones have been, I’d be leery of designing around the old published specs unless yours are still OEM and not been seriously abused with high enough power to heat weaken the motors; otherwise, ‘smart money’ is to measure their specs.

I sent a PM to the forum’s moderator about your sign-up problem, so hopefully it will be resolved soon.

WinISD or WinISD Pro alpha? Best to use the latter, for which I have many additional drivers plus there’s a tutorial and driver database here:

WinISD Pro Tutorial and Download (A detailed guide on how to use WinISD Pro) - Home Theater Forum and Systems - HomeTheaterShack.com

Downloadable WinISD Pro Files - Home Theater Forum and Systems - HomeTheaterShack.com

GM
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Old 13th June 2014, 05:48 PM   #4
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OP,
Is the GPA and the Altec vintage product the same thing? Which one you have...
(I would guess you have the new one.)
http://www.dvq.com/hifi/images/604e.pdf
http://www.greatplainsaudio.com/down...ec%20Sheet.pdf
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Old 13th June 2014, 07:11 PM   #5
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Quote:
Originally Posted by SNR View Post
Also I did join the Altec Users, but the website is messed up and I am only half registered lol. There appears to be a lot of technical problems there. Too bad, it's a good little site otherwise.
Hello I'm the Moderator over at the Altec Users Board and will see if I can help you with your problem.. So Sorry for your problems registering.. Steven is a great guy and will send him a PM ! I will try to get you fixed up in a hurry and BTW Welcome to the Board ! I assume you are trying to register under the moniker SNR ?


Regards ~ AB
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Last edited by Altec Best; 13th June 2014 at 07:18 PM.
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Old 13th June 2014, 10:34 PM   #6
SNR is offline SNR  Canada
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Quote:
Originally Posted by John Busch View Post
Great to see you want to get the most out of this wonderful coax! Box alignment and crossover are the obvious keys to your project.

First is to get an accurate measure of the woofers T/S values. Have you measured them?

I also assume you are aware of Jeff Markwarts interesting site about phase correct crossover solutions. Jeff Markwart's Corner - Phase Corrected Crossovers
I have not measured them yet. I will see if I can put together a testing rig this weekend. Any objections to using Rod Elliott's technique for this?

I did come across Jeff Markwart's crossovers, however I failed to mention that I acquired a pair of N-1500 A crossovers. If I understand Jeff correctly, I could just go with these networks.

Quote:
Originally Posted by GM View Post
Greets!

Well, if you research me [GM, GPM, among others] you’ll find my preference has been Harry Olson’s late ‘40s tall reflex [vented tower, column, MLTL] alignment since I was exposed to it in the ‘60s .

The largest cabs I recommend for < ~ 0.4 Qts drivers are typically Vb = Vas, Fb = Fs, so for the 604E, the largest MLTL can be up to ~27.5 ft^3, though the largest actually built to my specs IIRC was 17.64 ft^3 net/tuned individually to each driver’s Fs [< 30 Hz] by a professional horn blower in NYC and set up in a relatively tiny room/near-field listening app [home recording studio monitors? Can’t remember now].

Driven with a matching impedance SET, he was a ‘happy camper’, with solid bass down to Fs, but this was well over a decade ago now, so no clue if they stood the test of time.

Specs have varied quite a bit over the decades of re-coning, so considering how far out of spec some of GPA’s re-cones have been, I’d be leery of designing around the old published specs unless yours are still OEM and not been seriously abused with high enough power to heat weaken the motors; otherwise, ‘smart money’ is to measure their specs.

I sent a PM to the forum’s moderator about your sign-up problem, so hopefully it will be resolved soon.

WinISD or WinISD Pro alpha? Best to use the latter, for which I have many additional drivers plus there’s a tutorial and driver database here:

WinISD Pro Tutorial and Download (A detailed guide on how to use WinISD Pro) - Home Theater Forum and Systems - HomeTheaterShack.com

Downloadable WinISD Pro Files - Home Theater Forum and Systems - HomeTheaterShack.com

GM
OK I will look into the Olsen cabinet tonight.

I might be jumping ahead here, but will I be ending up with a 17 cu' cabinet or be prepping for a 27 cu' ? Size will not be a restriction for this project, but if there is diminishing returns beyond 17 cu' 30 Hz? How much lower would the additional 10 cu' go?

I will measure the specs. I don't think they were abused too bad. I think I am the 2nd/3rd owner as I bought them from the original owners son, possibly grandson.
They came in Valencia cabinets, along with the matching center console which had a Fisher 400 in it.

I thought last weekend that it was a home-built type deal by the way the amp was mounted. It was also hacky where the Garrad was dropped in.I was certain it was DIY which was good as I really did not want the cabinetry.
Well this morning I stumbled across the center console and speaker cabs in an unrelated image search lol. I had already tossed it, but a co-worker decided he wanted it. I'm over it now but I definatly wasn't looking to scrap anything Altec.
I won't be tossing the speaker cabinets now though. lol.

So aside from a recent Halloween party, I don't think the speakers have been used and abused all that much, but this is speculatively based on information from time of purchase.

I downloaded alpha and beta, but only installed alpha. Thank you for the links, I will find the tutorials helpful.

Quote:
Originally Posted by Inductor View Post
OP,
Is the GPA and the Altec vintage product the same thing? Which one you have...
(I would guess you have the new one.)
http://www.dvq.com/hifi/images/604e.pdf
http://www.greatplainsaudio.com/down...ec%20Sheet.pdf
Vintage version, I am not yet fully aware of the nuances between the two other then maybe the efficiency and surround composition.

Quote:
Originally Posted by Altec Best View Post
Hello I'm the Moderator over at the Altec Users Board and will see if I can help you with your problem.. So Sorry for your problems registering.. Steven is a great guy and will send him a PM ! I will try to get you fixed up in a hurry and BTW Welcome to the Board ! I assume you are trying to register under the moniker SNR ?


Regards ~ AB
No, but that is a good idea, however I think "SNR" was too short. My user name is "HighFy". If it could be SNR, that would be great. Thanks.

I am going to pop open the cabinets tonight as I only briefly look in the back of one them when I bought them.

Thanks for all the enthusiasm, I assure you it is mutual.
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Old 13th June 2014, 11:40 PM   #7
freddi is offline freddi  United States
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it sounds very good in the original Karlson but may not go "low" enough for your tastes - the sound is strong, vibrant - don't use any baffle step comp. in the xover.
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Old 14th June 2014, 12:38 AM   #8
GM is offline GM  United States
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Quote:
Originally Posted by SNR View Post
OK I will look into the Olsen cabinet tonight.

I might be jumping ahead here, but will I be ending up with a 17 cu' cabinet or be prepping for a 27 cu' ? Size will not be a restriction for this project, but if there is diminishing returns beyond 17 cu' 30 Hz? How much lower would the additional 10 cu' go?
Hmm, I see I could have phrased that a bit better…………….I just meant that his his idea of a home high sound quality system circa 1950, which included a large, tall cab with tapered back baffle, driver at the top to get it up to average ear height with a ‘critically’ damped vent at the bottom showed me a better way to do vented alignments.

Since it’s ‘only’ ~8 ft^3 tuned to ~75 Hz to suit his RCA drivers, it would only be a good one for the earliest duplexes without re-tuning as by 1950 Altec was using 8 ft^3/45 Hz alignments, though in a standard ‘lowboy’ reflex.

Until you have measured them and told us the particulars of your set-up, i.e. room details, planned speaker/listening position, electronics, not much point in speculating about cab size, especially since you want to do it with no EQ.

In both the huge 604 alignments, they were Vb = Vas, Fb = Fs and driven by matching impedance amps, which effectively raised the driver’s Qts almost 2x, ‘filling’ the cab to a ~maximally flat alignment, so they each had virtually the same amount of bass, just the smaller cab has a lower efficiency.

A lot will depend on the amp used and how close to a wall, corner they will be. Most folks I’ve done cabs for regardless of brand, model usually build as big as they can ‘afford’ to maximize tuning flexibility, then use some form of EQ to balance them out.

Olson’s ‘MLTL’:

GM
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File Type: gif Olson MLTL.gif (108.7 KB, 359 views)
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Old 14th June 2014, 01:08 AM   #9
SNR is offline SNR  Canada
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OK I will work on the measurements.

As far as particulars, the room is ~12 x 20 with the speakers on the 12' wall. This of course may change so I would rather have not have too room specific. That being said, I have always typically had speakers in a similar arrangement, which has the speakers in the corners kinda toed in a bit.

This puts me in the near field about 4'-6' away from each speaker. I am not so concerned with how it fills the room so much as the near field where I will be enjoying it 95% of the time.

They will be used in similar domestic situations in the future as well.

I have pondered corner-back cabinets, but in reality I can still place rectangle cabinets in the corners so I had not planned on corner cabinets although upon reflection I have not ruled it out.

Amplification will be primarily be SET 2A3 or on occasion SE 6BQ5, basically in the 2-5 watt range.
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Old 14th June 2014, 01:40 AM   #10
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Since you are able to measure the driver and are open to EQ, consider Linkwitz transform to solve your big box quandry. The new GPA version of 604E has power rating of 100W, I don't know what the original's max power was, but even 50W will allow enough EQ to at least duplicate the sound of a Qtc .5 box (Vb=Vas) in a Qtc .7 (or maybe even Qtc 1) sized box. A small box is easier to brace and damp so far less box noise, better WAF, no reflex port distortion, etc.

More: TA Speaker Topics - Designing a Linkwitz Transform
Linkwitz Transform Subwoofer Equaliser

2A3 may not be enough power for bass EQ, but SET damping isn't best for clean bass either. Weigh the pros/cons.
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