Altec 15 Series II

I've just made a deal to trade my bass guitar roadbox with two JBL K140 15" speakers for a single Altec 15 Series II speaker enclosure in order to get something smaller that will fit in my import car. The fellow who's trading the Altec 15 Series II just messaged me and says he's not sure if the speaker is designed for bass. He says he tested it with his bass and there's a lot of high frequency content, but he says it sounds great with his guitar. I was under the impression when I arranged the trade that the Altec 15 Series II were bass speakers, but I'm wondering now if that series also included guitar speakers. I'm unable to get any additional information, so I'm hoping you can tell me if what I'm trading into is a bass speaker. Thanks in advance for any information you can offer.

Apples and Oranges.

You’ll likely blow the woofer (not an instrument driver), and a fairly expensive compression driver.
I get wanting a smaller bass cab. This is 75lbs though and a studio monitor, not a bass cab.
Kinda hoping this is a first of April type joke/troll.

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Originally Posted by Spellcaster

I've just made a deal to trade my bass guitar roadbox with two JBL K140 15" speakers for a single Altec 15 Series II speaker enclosure in order to get something smaller that will fit in my import car. The fellow who's trading the Altec 15 Series II just messaged me and says he's not sure if the speaker is designed for bass. He says he tested it with his bass and there's a lot of high frequency content, but he says it sounds great with his guitar. I was under the impression when I arranged the trade that the Altec 15 Series II were bass speakers, but I'm wondering now if that series also included guitar speakers. I'm unable to get any additional information, so I'm hoping you can tell me if what I'm trading into is a bass speaker. Thanks in advance for any information you can offer.

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Originally Posted by grumpy

Apples and Oranges.

You’ll likely blow the woofer (not an instrument driver), and a fairly expensive compression driver.
I get wanting a smaller bass cab. This is 75lbs though and a studio monitor, not a bass cab.
Kinda hoping this is a first of April type joke/troll.

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I wish it was, Grumpy. I made the trade, and while it seems to sound okay....No audible distortion or signs that the driver's in distress, but it doesn't sound particularly deep. There's some aspects of your reply that don't add up for me. It sounds like you're describing a manufactured cabinet/driver combination. What I've got is a typical looking bass speaker enclosure and what I thought I was getting was an Altec bass guitar woofer, with a white cast frame...like a 421A. It's beginning to sound like I was misled a bit on what the driver was going to be. I guess I'll have to disassemble the cabinet and see what's inside. I'll come back here and report my findings, probably within a day, and hopefully you can confirm to me if it is what you're calling a compression driver. If it is the wrong speaker, I'll have to go shopping for something else, and perhaps you'll be able to advise me if what I have is saleable and what the value is. Thanks for your response so far...I hope you can give me a bit of advice after I open the box up and see what the tag on the magnet says.

Quote:

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Originally Posted by grumpy

Apples and Oranges.

You’ll likely blow the woofer (not an instrument driver), and a fairly expensive compression driver.
I get wanting a smaller bass cab. This is 75lbs though and a studio monitor, not a bass cab.
Kinda hoping this is a first of April type joke/troll.

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Okay....I've got the cabinet open on the operating table. What the sticker on the magnet says is "Altec Lansing 418-8H Series II 8 ohms Musical Instrument Speaker". So, I'm assuming maybe without the additional 418-8H, it bears some resemblance to the identification of the compression driver /studio monitor you thought we were talking about. I feel quite relieved that it isn't dramatically wrong.

It is a cast white frame with a black label on the magnet, and looks for all the world like a speaker I had in my hands last summer that did come out of a bass guitar speaker cabinet. However, the one from last summer was a 421....Not a 418. So, to get back to my original question - Is this speaker designed for bass, or is it only designed for regular guitar? The speaker I have in front of me, the 418-8H, when I look at the specs online says it is rated for continuous power of 150 watts and frequency response of 45 to 8000 Hz. When I look at the specs for the 421, it's frequency response is 35 - 4000 Hz. with rated power 100 watts.

So, is the 418 simply producing more high frequency response and less apparent bass because it extends to 8K instead of 4K. Or, is it possible that the box it's in is so undersize that it's limiting low end response? I just measured the interior volume and it's 3.2 cu ft.

Also, since this is a universal type enclosure that wasn't made specifically for this driver, there's no real science behind the vents that have been cut into the baffle board. I'd like to post a picture but there doesn't seem to be any apparent way to do that on this forum. There is a rectangular cutout above and below the speaker, each one 2" x 14", so the total cutout area is 56 sq in. and these are just cut-outs in the baffle board...There's no duct attached that extends into the depth of the cabinet.

I used to build speaker boxes for car stereo, so I'm aware of the influence duct size and length can have on response. However, I have no reference dimensions to base things on. I found good reference materials on this site that let me customize the ducts size and length for the cabinet that I just sent away with the K140 JBL's in it, but I can't find anything similar here for the Altec instrument speakers. Can anyone suggest a source for the information I want, or does anyone have any insights that would be helpful to me here?

I'd really appreciate any guidance you can give me. The speaker/enclosure is sadly lacking in bottom end and I'm groping in the dark trying guess at this on my own. You guys are the closest things there are to experts on Altec product. Can you help at all?

Ah. Perhaps there were two completely separate Altec system 15 lines, if so, “my bad.”

The one I was referring to is a -not- an instrument cabinet and it would be entirely inappropriate to use as one.

https://greatplainsaudio.com/wp-cont...-Catalogue.pdf

see pg 6

If the title had been Altec 15” series II driver in a box, I may have been less confused :o:

I believe the 418 was intended more as a guitar speaker. Could be used if you were careful not to overload it below the box tuning. Sort of like using a D130 vs 140 in jbl-land.

Edit 11/3:

421 has a lower resonance and is more appropriate for bass. I've used 12" guitar cabs for bass and it sounded great with punch, but no thump, so YMMV.

Also, re uploading pictures (there are some size constraints ... 1024 pixels wide usually is fine):

see Settings (top right) My Settings (category on left after choosing Settings), General Settings (down a bit on My Settings area), then scroll down to see editor options.

Glad you're happy with how that all worked out :)
Happy Holidays!

I know I'm too late now, but in your case I'd have built two new enclosures for your K140's, for example according to the 1975 enclosure plans from this site. Then you'd had the choice to get one or both enclosures with you, according to the individual demands of your gig. And the K140 really makes a great bass guitar speaker in the 3.75 cuft enclosure from the plans! I've also got/built one in about 1978.

Best regards!