Altec loudspeaker : Newbie needs advice please :)

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Hello audio Gurus :)

My name is Craig, I am a 27 year old PC tech from icy cold Maine (USA)

I have no DIY audio expirience whatsoever but am a big fan of cabinetry (I make arcade cabinets as a hobby)

My friend Dana gave me an Altec 416a 15" driver from 1964 and the plans to build an Altec 620 cabinet to put it in. I have finished much of the cabinet work but now I am spumped as I cannot find a newbie friendly "How to build a crossover" anywhere !

The driver specs are : 16 OHM , 35 Watts

Could someone please tell me how to build a simple crossover for this driver ?

I have basic wire soldering expirience and a "Martin Sound" catalogue handy to order any of the pieces I might need (I also have a bunch of capacitors and mosfets from power supplies and computer monitors)

I just can't find instructions ...

Thnk You very much in advance, I look forward to finishing this cabinet.
Craig
 

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>My name is Craig, I am a 27 year old PC tech from icy cold Maine (USA)

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Greetings from a much warmer locale!

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>My friend Dana gave me an Altec 416a 15" driver from 1964 and the plans to build an Altec 620 cabinet to put it in.

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I know you don't want to hear this, but this cab wasn't designed for the 416, though it can be made to work. For now, I recommend not doing any finish work on it until you dial in the box tuning as I'm pretty confident you won't be pleased with the vent dims as is.

BTW, will it be driven with a tube or SS amp?

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>I have finished much of the cabinet work but now I am spumped as I cannot find a newbie friendly "How to build a crossover" anywhere !

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There's websites that calculate textbook XOs, which is what Altec used for decades, but you can do better if you're willing to do a little measuring. About the best treatise on XOs on the net is Wayne Parham's Pi Align document, but you do need to understand basic electrical filter theory.

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>Could someone please tell me how to build a simple crossover for this driver ?

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Uh, you don't say what the XO point is, what it's XOing to, or what the app is.

GM
 
Lionel said:
Is the money for an answer ? :D


Thanks Lionel,

The bill is there to give a sense of how large the cabinet is, I was going to use a 12" ruler but the colors blended and it did'nt look right, then I used my assistant (pic attached) but humans are variable in size so I settled on the dollar :)

Dig it ?
 

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Hello GM,
Thank You very much for your reply, I bet together we can quickly diffuse my confusion on this matter and I can finish the cabinet :)

I will answer your questions first.

Q. will it be driven with a tube or SS amp?
A. I plan to hook it in-line with my computer speakers for robust sounding explosions in videogames. Currently (but may change) it has a 5watt computer speaker amplifier.

Q. Uh, you don't say what the XO point is, what it's XOing to, or what the app is.
A. Maybe crossover was'nt the correct term, I want to build something to filter out frequencies over 500, so my woofer won't be playing high frequencies. Is that called a crossover or a filter ?

I have a few questions for you as I did'nt understand all of your reply.

1." this cab wasn't designed for the 416"
What cab is the 416a supposed to go into ? What driver is supposed to go into the 620 cabinet ?

2."... dial in the box tuning"
How is that done ?

3."you won't be pleased with the vent dims as is"
What are vent dims ?

Thanks!
Craig
 

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GM

Member
Joined 2003
Q. will it be driven with a tube or SS amp?
A. I plan to hook it in-line with my computer speakers for robust sounding explosions in videogames. Currently (but may change) it has a 5watt computer speaker amplifier.

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OK.

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Q. Uh, you don't say what the XO point is, what it's XOing to, or what the app is.
A. Maybe crossover was'nt the correct term, I want to build something to filter out frequencies over 500, so my woofer won't be playing high frequencies. Is that called a crossover or a filter ?

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We normally just say crossover or XO, but it's technically a crossover filter. Not having any measurements or familiar with the computer system's audio, assuming it can handle the 16ohm load and passive components all I can do is give you the textbook values Altec used for the 416: 14uF in parallel with the 416 and low DCR (>0.3ohms) 7.2mH in series.

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1." this cab wasn't designed for the 416"
What cab is the 416a supposed to go into ? What driver is supposed to go into the 620 cabinet ?

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The early 604 series duplex or 515, but since you're using SS and need a relatively low Fb (box tuning), the 620 is big enough for your app as long as the video games don't go below ~35Hz. I don't play them so don't have a clue. If they do then you'll need to be able to roll off the signal below this point.

The 416 was normally loaded in the 825 (A7) or 612 cab.

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2."... dial in the box tuning"
How is that done ?

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By changing the vent size and/or length.

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3."you won't be pleased with the vent dims as is"
What are vent dims ?

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Dims is short for dimensions, which in this case is the 2.5" x 11" slot in the baffle. Anyway, try it and if it sounds too boomy and/or rolls off too high let me know and I'll work up some others to try.

I can't tell, but I assume you left out the big hole in the back.

BTW, use a vacuum cleaner with dusting brush to clean the vent screen and store it face down, don't want any dust to get in the gap.

Cute helper! :) I had some but they're 30 somethings now with their own.

GM
 
If you're using them for computer games, just hook it up with a coil and be done with it. Those games will sound like never before. Remember if that's all you're using it for, it doesn't really matter how accurate it is, the noise generator is a computer. There's nothing "natural" about it. Lotsa guys do this with a lack of regard for the tuning of the cabinet etc.

You have a beautful driver in your possession. There are others who only dream of having one. It will sound just fine, matched cabinet or not.

Oh, and when you are interested in Altec projects, that link in the thread above is a great one.

Cheers,
Cal
 
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