DIY Altec Clone Speaker Build Instructions/Spec?

[karlsushi]

Hi all. New to the forum and hoping for some advice from what seems to be a very clued-up bunch of folk on all things Altec 🙂

I'm based in the UK where sadly, Altec speakers rarely, if ever, come up for sale.

This journey started when I came across a great range of Altec speakers on ebay from a company called LaJazzAudio (based in LA I believe). These guys seem to do worldwide fully-insured shipping, but the costs are going to be pretty significant if I went down this route, by the time you add the shipping (around $700+) and the UK import duty (20%), so given the risks involved and associated costs, I'm very hesitant about going down this route.

These in particular have me drooling though:

So I am thinking about having something along these lines built to order by some knowledgeable and friendly folk over here in the UK. I'm not a very practical person and the thought of going down the DIY route myself is a bit of a non-starter really, but I am interested in being part of the design process.

The plan is to go for a relatively straight-forward 2-way along the lines of an Altec Valencia or indeed the 824A Iconics pictured above, probably using modern driver equivalents rather than original Altec drivers (again, because they are hard to get hold of over here). GPA are too expensive too (especially after shipping and import tax) so looking at Faital Pro or Beymer drive units, using a 10" or 12" bass unit crossed-over to a 1" compression driver (with horn) at around 800Hz. Would probably go for a ported bass reflex design.

Initial thought is to use the original Altec Valencia cabinet plan. Am I being too simplistic and could this become much more complicated than hoped if I'm planning to use drivers that will by all accounts be very different spec to the originals used in the Valencia?

So my first main question is whether anyone is aware of a ready-made specification/instructions for building a 2-way Altec clone of this kind that can just be copied rather than trying to reinvent the wheel?

At this stage, my main concern is having a speaker that looks great and sounds rubbish.

Any assistance/advice greatly appreciated.

Cheers

Karl

 

[Time60]

Why use a "modern" driver? a better driver than 414/416 i hard to find.

 

[asilker]

Why use a "modern" driver? a better driver than 414/416 i hard to find.

Karl's profile appears to be UK - finding drivers in good shape may be more challenging or cost prohibitive than in CONUS

 

[karlsushi]

Karl's profile appears to be UK - finding drivers in good shape may be more challenging or cost prohibitive than in CONUS

Correct. Unfortunately, Altec stuff is very hard to come by over here in Ol' Blighty ☹️

So I'm looking at drivers from Faital Pro, Beymer etc which can be obtained more easily over here.

 

[Audionut]

Karl's profile appears to be UK - finding drivers in good shape may be more challenging or cost prohibitive than in CONUS

Yep, just checked UK flea bay and not much going on out there. He’d be shipping from Japan or US.

 

[fleasbaby]

Hi all,

Does anyone know of anywhere it's possible to obtain ready-made instructions for building Altec speaker clones? I am specifically looking for a kit/instructions for a 2 way speaker, similar to the Altec Valencia or Iconic, but using modern drivers.

Any advice/assistance appreciated.

Many thanks

Karl

Hi Karl, check out the JBL 322CT...not sure what availability is like in the UK for these...

The specs for its JBL-built back-box are eerily close to the specs for the Altec 614 cabinet. I am using a pair in a pair of cabs very close to the 614's parameters.

Regarding the driver, I removed the transformer, and use the stock crossover. I removed the mounting bracket for the crossover from the back of the woofer, and mounted the crossover to the inside of the cabinet wall instead. I also did a horn-mod (like Ojas does with his Art Bookshelf). I was lucky enough to have a friend gift me a pair of Altec 32C horns.

Its a "poor man's Altec", but it is hits the spot in many, many ways for me personally.

 

[jimreeves]

This link may help you...

1974 Enclosure Manual

 

[karlsushi]

Just to say I may have duplicated this thread with a much shorter message. I realise now that this post was awaiting admin approval as I'm a new user, but I couldn't see it anywhere so thought it had been lost.

Apologies for muddying the forum!!

 

[J. Frum]

A willingness to have cabinets the size of small refrigerators built is a good start for a high-sensitivity sound system. How big is your room, how bass-hungry are you, and do you intend to use valve amps?

My suggestion is to copy the Altec aesthetics, but choose enclosure volume and tuning according to the woofer you select. The preferred freeware is WinISD, but one of us can probably model the box for you once a driver is selected.

There’s a lot that goes into crossover design, but you’re probably okay winging it, again, with some research and advice. It’s entirely possible to get started with an off-the-shelf jobber if you’re all thumbs.

Generally speaking, modern constant directivity horns would be crossed over to a 12” around 1200-1400 hz. 10” higher than that.

 

[Mike414]

The essence of the "Altec sound" lies in the woofer, in my opinion. Horns and compression drivers have more leeway, provided the woofer is an Altec. Anything else can still sound great, but in a different way.

There are a lot of DIY two way horn speaker projects on diyaudio.com. Many are based on Faital Pro and Beyma components.

Take a look at this project posted on this forum.

New DIY speaker build (based on Altec 614A)

Take your time, read up, and have fun.

 

[Thermionics]

If you can find a pair of Magnavox 232 (or similar Allen Organ) 15" drivers (the ones that look similar to a Jensen P15N), they've definitely got a bit of that Altec 414 magic to them. That might be easier to source in the UK for a reasonable price.

 

[karlsushi]

How big is your room, how bass-hungry are you, and do you intend to use valve amps?

Room is decent-enough size, around 9' across x nearly 30' long, but I am still a bit restricted on size for aesthetic reasons, given this will be our family living room. I'd say Altec Valencia proportions would be the upper end of cabinet size.

Not so fussed about big deep bass. I'm using full range stand-mount speakers currently, so most things are going to go deeper than those.

And finally yes, I am using SET valve (tube!) monos currently, albeit using 805 output valves, which produce a healthy 40W. But I have thought about a 2A3 or 300B amp at some point, so it would be nice to have speakers that can be driven by a flea-watt amp.

I love what my current speakers do and they're going nowhere. They do refinement and detail and they image like nothing else, but they don't do that big, in your face, dynamic style that horns seem to bring to the party.

 

[gortnipper]

I live in NZ and have several sets of Altec drivers that I have had shipped here over the years from the US. If you are looking for a medium+ sized speaker to have built and looking to reduce some risk, I would look for a set of 604s and build a 620 cab (or, even a 612 - but go for a 620!). That will fill your room with very nice Altec goodness and you would not have to source and ship multiple items from multiple sellers.

Dont bother with an Altec crossover, either build yourself a Markwart xo or buy one of Werners (my fave). Altec's xo's are not the best, IMHO.

In fact, I would contact Werner (details here) and ask him if he knows of any drivers for sale in the wider EU. He is well connected with lots of very knowledgeable people across Europe, and can be trusted.

 

[gortnipper]

Altec604-8k

Verkauft steht ein Paar original 604-8k , original Weiche mit Gehäuser von Tischler gemacht. Sehr...,Altec604-8k in Koblenz - Koblenz

www.kleinanzeigen.de

 

[MrEd]

Were any Jensen drivers sold in UK or Europe back in the day?
That could be an alternative.

 

[Andyman]

Nice, but I have some words of caution.

In spring I acquired a set of raw 604Bs and wanted to have them face off vs. my A7-MR994s with winner take all. Diving into the tonnage of Altec info here I first built a crude extension on a JBL club cab and found it interesting enough to make a mockup of a 620 cab, so I built a single 620 cab out of some old birch plywood my daughter ahad left behind in the home she bought.

I hooked up the A7 on one side and the 604B on another and used my smartphone RTA to level match them and was shocked to see that the A7 totally blew out 604B. I'll post a video of it here; use headphones or decent computer sound system as a smartphone isn't going to produce the A7 bass.
I contacted one of our local altec gurus and we ran some tests of my 604B vs his GPA 604s and a 604C he had and they balanced well, even with the 604 mounted in a 3.0 ft3 cabinet. I took his 604C home and played it in both his 3.0 cab and my 9.0 620 to get the same results. Accordingly; I'm keeping the A7s and moving on.

So the words of caution are basically build a mockup before you commit to the good stuff. Reason #1 is the first build will reveal any production issues you may have working with large panels as cutting square, doing EXACT 45 bevels on large sheets, making the speaker and port cutouts. and using dowels. #2 is you won't spend a small fortune in materials for high end plywoods and veneers on some cabs that don't deliver the audio nirvana you hoped for.

I haven't built a large speaker cab since 2009 and this Econowave using JBL LE14s, and I did a mockup on it too. It's about half the volume of the 620.



Here's the video of the 604 vs the A7. It was mentioned that the placement may have had some effect, but the lesson remains the same.

 

[karlsushi]

look for a set of 604s and build a 620 cab

This is certainly looking like the most straight-forward option I've come across as a first attempt.

There's a pair of the 8 Ohm 604-8G drivers on ebay currently with free shipping from Japan, but still pretty spendy at $2.1k. If going down this route, I think I'd like to find a pair of the 16 Ohm units as my SET amps have 16 Ohm output transformers fitted.

Looking at the cabinet plans for the 620, it looks like the cabinet is split diagonally across the middle. Seems like an illogical thing to do if the port is in a separated section, so assume this may just be bracing?

 

[Billet]

Celestion Blue might be a great alternative... You can listen to some clean guitar clips on YouTube to get an idea of their sound. They should be easily sourced in the UK

 

[Mike414]

Interesting project here with all the details of cabinet construction and the crossover. 12 inch two way with a horn.

Mezzo Calpamos

 

[mhardy6647]

Apropos of @Andyman's (great) post above, allow me to share my two cents' worth on Duplexes.
I love the sound, tone, and presentation of Duplexes (in my case, 604E with Mastering Labs XOs) -- but I eventually became obsessed (!) with fixing one glitch. For me (and I think age-related deterioration of high-frequency hearing and concomitant, I think, tinnitus) the issue with 'em was/is limited dispersion of treble. The sound of 604 family members is marvelous as far as it goes, but they betray their nearfield monitor heritage as becoming a little hard to live with in a large space if one doesn't want a head-in-a-vise listening experience to hear them at their best.

I ultimately ended up embracing (for better or worse) the notion that the woofer part of classic Duplexes is kind of, sort of a 515B, and the treble driver is kind of, sort of an 802D. I leveraged the lovely pair of "Billfort" cabinets I'd had built by my friend, woodworker Mike Berg and ended up with 515Bs in 'em and (as of now) 802Ds on 'em loading EH-500-2 (EMILAR) horns... and sweetened with B&C DE35 used as "supertweeters" (super being relative given my hearing at this point in my life). EDIT: I'll skip details of the XOs as they currently stand in a token attempt at brevity.

I would absolutely never (!!) discourage anyone from goin' Duplex -- but I think the above could be helpful perspective to add to the deliberation process.