Altec 515LF modern replacement?

[SunRa]

Hello,

This is more of an intelectual curiosity but here it goes.

Do you have in mind any modern replacements (BMS, 18Sound, B&C, AES, that sort of "modern") for Altec 515?

I am interested in low fs (around 25Hz) coupled with high sensitivity (over 98db), and this is usually meaning low moving mass.

The only similar speakers I can think of are Supravox 285 and 400.

Looking for your suggestions!

edit: another hint is that if I'd use this I'd do it in a closed or vented box, not a horn which is the usual application for an Altec.

Thank you!

[ScottG]

There are drivers like this.. but are they necessarily more "modern"? Also most are hideously expensive. In addition to most of the Supravox 400 range, there are drivers from GOTO, ALE, AER, etc.. Getting High eff. AND low fs is the problem. Ex.:

Studiobass

Note that even most of these exotic woofers have very low compliance, so they aren't quite the same. Even the more "regular" JBL 2235H (no longer produced) has a low Qm. ..the field coil Supravox 400 with a stronger voltage supply is an exception. Also see:

A515WVL | Great Vintage Loudspeakers

Further - the 515 probably isn't as efficient as 98 db (..prob. more like 97 db). It will likely get its greater db rating from the enclosure - augmented via horn loading or a higher tuning freq. for the bass reflex design.

There is however a "poor man's compromise":

Eminence EMI-1550 15" High Efficiency Sub from Madisound

Get an additional magnet for this thing, positioned (spaced) correctly for added gain - and you should be looking at about 97.5 db.

I should also note that if you increase fs by about 10-14 Hz then your choices will expand quite a bit.

[Inductor]

Kind of an intellectual response too, look at this contender in pressed steel, maybe not the same.
VOLT Ps15/300

Those AER look nice (they all look nice and w/low Fs), and they are the 4 months well spent, better than the 2 years for the Gurus/Sweden.

[Pano]

How about the GPA 515. If you want a 515, why not just get one?

Great Plains Audio's LF Loudspeakers

[ScottG]

Originally Posted by panomaniac

How about the GPA 515. If you want a 515, why not just get one?

Great Plains Audio's LF Loudspeakers

The link is also in his post.

I think it was more a matter of finding a driver that is similar yet better (at least measurably), and if possible: less expensive.

The thing is, no "large" manufacturer wants to produce a driver that requires significant volume to get a decent low-end response. Add to that increased eff.. and well, you are really pushing Hoffman's Iron Law into unreasonable domestic use (..a.k.a "Fridge +" size, and even then for only modest bass extension). Of course the 515 was used in unusual designs (at least by modern standards), but even then most designs were not only large, but still didn't have much bass extension.

[SunRa]

Thank you guys for your suggestions.

The Volt and the Eminence drivers linked by Inductor and Scott are indeed new to me, I'll look closer at them. The one from Volt looks great, but that measurement posted there might be misleading, with almost 100g moving mass and 99dB, the woofer might be closer to the typical PA woofers than what I am looking for. The low end rollover is smoother though, which is exactly I am looking for.

Unfortunately, no ALE, GOTO, Kilimanjaro, and not even GPA for me... These are way to expensive to afford them. Not even the Supravox 400. Most probably, if I'll go with the plan to use a woofer similar to the 515 I'd go with Supravox 285GMF which has a relatively decent price.

Originally Posted by ScottG

I think it was more a matter of finding a driver that is similar yet better (at least measurably), and if possible: less expensive.

Exactly yes, that I mean by modern: similar yet maybe better (copper rings, etc ), and also mainstream, which would make it cheap.

However, how Scott already put it,

The thing is, no "large" manufacturer wants to produce a driver that requires significant volume to get a decent low-end response.

To give another hint of what I'm thinking of:

This woofer would complement a large midrange (AE15TDM, 18Sound12NDA520, this type of highly efficient stuff), and would run in parallel with the midrange starting at about 80Hz.

The enclosures would be sealed, and I need this second high efficiency woofer to have a reasonable flat response down to 50Hz by summing the two responses.

Think of the inclosures of something like this:

[SunRa]

By the way, look at the T/S of the kilimanjaro series. At 10V in the field-coil you get 99.4dB and have an fs of 24.3 Hz. Why they don't make speakers like this anymore?

[Pano]

Originally Posted by ScottG

The link is also in his post.

Ooops! Sorry. Must not have seen the link against the pale blue background.

The Altec drivers were never cheap, still aren't. Sometimes you can pick up used frames for cheap and have them reconed. Still not bargain basement, tho.

It will be interesting to see what you come up with.

[SunRa]

Thanks,


I did some WinISD sims and it's just outrageous, the Altec 416C for example trumps over any 15" up to 21" eighteensound LF woofer at 50Hz in terms of relative gain. I know this is not entirely representative but you've got the point. No matter how you put it, the Altecs are 2-3dB more efficient when used in closed boxes.

[ScottG]

Originally Posted by SunRa

To give another hint of what I'm thinking of:

This woofer would complement a large midrange (AE15TDM, 18Sound12NDA520, this type of highly efficient stuff), and would run in parallel with the midrange starting at about 80Hz.

The enclosures would be sealed, and I need this second high efficiency woofer to have a reasonable flat response down to 50Hz by summing the two responses.

There is always someone trying to break Hoffmans Iron Law..

There *is* however a way to "bend" it. Aperiodic with a woofer that is pretty much "unacceptable" by modern standards. The Selenium that Panomaniac uses should work in a smaller volume (..say 4 cubic feet). "Tuning" it to lower it's LF "knee" and also flatten out phase and group delay. Considering room gain and some output from a midbass driver, it might get you closer to what you are looking for.