Altec 604 E reconing options.

[GM]

Greets!

FWIW, even though the ?E? is a very popular version I?ve the most experience with and most used in recording studios AFAIK; the original with its much larger horn and nominally 1 kHz XO is the best of the series since it has an XO that matches up best overall with a 15? in general [with around 900 Hz being the ~ ideal], not mention sounds best to me and AFAIK everyone that?s been fortunate enough to compare the original to any of the later small horn models.


All things considered then, buying a new pair of the S3 is what I would do since its horn is larger and its profile produces a much better power response overall, probably even better than the original, though disappointed that GPA didn?t go the ?extra mile? to get the overall best horn/woofer match-up. I guess they didn?t want to get too far a field from the 604?s ?signature? [vintage] sound.

Also, if you know someone locally with good XO design skills, I recommend buying them without XOs or at least not using them as is and have a proper time delayed one developed based on Jeff?s:
http://home.earthlink.net/~jmarkwart/sitebuildercontent/sitebuilderfiles/604_8Hpcwmfeq.pdf

Be sure and read about omitting HF loading caps in case they are standard on the S3, which of course will affect the XO design if you choose to try it: http://home.earthlink.net/~jmarkwart/id21.html

Anyway, please keep us periodically updated since as you know, there?s no such thing as having too much published ?hands on? experience for others to help make an informed buying decision.

GM

[charly1944]

Hello GM,
Thanks a lot for your very useful and interesting information.It is the first time that i hear that the first generation 604 (i guess you are refering to 604 and 604B)sounds actually better that the later one.I have indeed always struggled with the high crossover point (1500 to1600)which gives a hard job to the woofer and may be the cause of the shoutiness i have heard with some 604E i have listened to.Thanks also for advising me to read the recommendation of Jeff Marwart regarding cross over and loading caps.I contacted him and he was kind enough to answer my questions.He also recommended the GPAIII with the help of a sub.
Today,i am back to square regarding the option vintage vs GPA since i missed the 604 E opportunity.
Incidentally,my local reconer,who is supposed to be a competent one is telling me that he has low frequency cones produced by Nuway in the US which are the original Altec woofer since Nuway was producing those cones for Altec.I am not sure how to check wether this info is reliable . Any body who can comment on that with a documented information is welcome.I 'll keep you posted with the development of my project.

[GM]

Greets!

You're welcome!

Specifically some of the 604Bs sold, so I guess I shouldn?t refer to them as the ?original? per se. The earlier versions quickly came and went as they experimented with XOs up to at least a nominal 2 kHz and maybe other design aspects I?m not aware of [I don?t recall ever being exposed to any specs of these except in old sales literature the local distributor still had back in the ?60s]; presumably to find the 'sweet spot' trade-off between sound quality [SQ] Vs power handling and/or off axis response in the earliest days of stereo experimentation. Even then, Altec apparently allowed the buyer a choice and/or specified different XOs depending on the app as I've seen 604Bs with 1.5 kHz XOs pulled from a radio station monitor system upgrade.

Never heard of Nuway, but then I never bothered to do any re-coning since I was fortunate enough to have easy/cheap access to both plenty of used drivers and an excellent re-coner with magnetizer only a few miles away. Frankly, I thought Altec made their own based on what I saw in a ?68 plant tour, though don?t recall actually seeing them made, but it seems reasonable that due to the drastic changes to the company in more recent times that it would farm out an increasing number of parts/subassemblies same as happened in other markets.

WRT speaker/horn ?shout?, this is usually due to improper frequency shaping [EQ]. With vintage speakers designed for high output impedance, just switching to a low one [PP tubes and especially SS] automatically causes it to a greater or lesser extent depending on the speaker?s design, XO point/slope. In the 604E?s case, shelving the horn by ear will roll off the extreme HF too much, so the mids tend to be too ?hot? relative to the woofer?s output, so the ?fix? is to level match the mids to the woofer, then wire a by-pass cap around the XO to let some portion of the HF through unattenuated.

Unfortunately, it took Altec till the mid ?70s to do proper driver, XO designs for ~ pure voltage amp loading in a ?too little, too late? attempt to maintain/recover lost market share.

GM

[charly1944]

Thanks GM for all this valuable information.
I am giving myself 2 months before i go to the GPA brand new solution.I am using this time to try to listen to them here in Paris.Meanwhile, i am looking actively for either a good pair of 604E in mint condition,with original cones and diaphrams ,to be sent to GPA for remag or in average condition,but at a low price ,to be reconed and restored by GPA. They are difficult to find .I see much more 604 C and D,some of them in pretty good shape,but i cannot find any specs about them.I understand that the C and D are pretty similar and read that their Fs is around 50 hz.This looks pretty high to me.That is why i am more interested in the E .Any solution, apart from a sub,to get some bass out of such drivers.Is a reconing of an old 604 D with 604 E diaphragms going to mitigate the problem or is it only an insult to collector without any added value in terms of bass extension.

[GM]

You're welcome!

B,C, D series were all listed as having a 40 Hz Fs, but never measured any, so don't know how accurate this is. I just know all the basic factory cabs recommended for them were tuned to around 42 Hz and since they tuned to Fs back then...........

Qts will be low to couple to a high output impedance and Vas will be high to keep efficiency up, so about the same as the original 'E' except for a published ~25 Hz Fs that in reality averaged 29.5 Hz in all the measured specs I've seen; whereas the 8G, 8H, 8K, 8L averaged 26.6 Hz. Based on these, the B, C, D, series may indeed have been closer to 50 Hz, but then what really matters is how much does cab, playback loading drops it.

No clue about re-coning, that's for GPA to answer, but I'm guessing that there's only one re-cone kit available for 604s these days and I'm betting it's not going to be the one listed for any older than the E and maybe not even its original. For sure, there's no early 515, 604, 803, etc. series paper surround cone kits left and why good condition originals go for major 'coin of the realm'.

GM

[cradeldorf]

FWIW I have always felt my "C" sounded better than my "E".

[GM]

Interesting, can you be more specific? I don't recall ever being 'up close' to a C or D, jumping from a well used B in an original A5 used for school PA apps to another person's E that I got to try in different cab loadings.

[charly1944]

Thanks for the info.Which type of cabinets and crossover do you use?Have they got original cones/diaphragms or are they reconed with GPA cones?Are you using a sug with them?Any body knows what the reference D I&#39 means for a 604 D?