Another Bargain driver to try

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I have seen this before and it looks interesting but did not know what the T/S params were. The pdf sheet is very different than what is posted on MCM website. Seems like quite the bargain though. I will put it in some sims with a MLTL and see how it fares. 90 Hz fs, 5 liter Vas, 89 dB efficiency, with Qts of 0.6 seem like nice numbers for a good all around driver.
Thanks X,

The 11 year old, has been watching me build all these enclosures, and wants to build a set for his room. It would be a fun project to do together. Granted they don't have to be Audiophile quality for his room, but the better they sound the more excited I will be. haha.
I think this design may be something you can try with your son. It isn't a bad driver, but may need some augmentation with a tweeter - try without first and see how you like it.

Bipole MLTL with HKM XF-131-828: 7 in wide x 13 in deep x 42 in tall, driver at 10.5 in from top, down firing vent is 4 in x 4 in (or equiv CSA) x 2.5 in long, set vent exit at 3.5 in above floor with legs, stuffing in top 2/3rds of line as usual.


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Very cool. Thanks again X. Can I fold it 3 times so it would be 3- 14" paths. Stuffing 2 of the paths and putting the vent at the end of the last path? Can't draw up what i'm thinking but I can later.

He even saw some PVC tube enclosures that he liked. I got a 6" pvc heater at work so I could bend it into any shape. Curly Q so to speak. I'm thinking like a 11 year old now!!! Way outside the box
X i was only going with one driver per enclosure. Nothing too fancy. I could use 1/4 wave calc with the pvc pipe. Cut to length and then throw it in the heater and bend it into a shape that meets the boy's approval. Port the end and have him throw some paint of his choice on it.

M cutting it into a Z shape with 45 degree cuts would be cool too. I have access to a plastic fusion tool that would work amazing on the joints. No glue needed. 500 degrees works wonders on pvc. haha
rocket speakers

Well the boy and I have been having some fun in the garage. Mad scientist style!

What we have at this point is a 1/4 wave TL 66" overall for a tuning of roughly 50hz. The speaker is placed at 22" and the line is stuffed up to 44" with the last 22" open.

It sounds pretty good for what we are working with. The next step is to place 4" to 2" reducer at the 44" mark (where the stuffing ends) and finish the length with 2". Then we can cut the 2" to taste for tuning so to speak. MLTL-esque

In the end will come up with approx 6' tall rockets with fins for stands. Even if they don't sound the greatest the boy and i had fun building them and he will be proud to show them off to his friends.


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Yes we are the mad scientists. I wish had some hair like Gene Wilder just for effect!

Thanks X, I will experiment with the reducer. We have plenty of old pipe to play with. I asked him what he wanted for shapes and he said rockets so.... rockets it is. He's the lead designer on the project and I'm just the silent partner. haha
Well they're up and running.

The pipe on the left is 66" to the reducer and then has a 12" piece of 2" on top. It is only stuffed to 44"

The pipe on the left is 66" also with no pipe on the reducer but is stuffed completely to top.

The fully stuffed one sounds a bit punchier with just a bit less extension. I don't have anymore 2" or I would have tried an even longer piece on top. I'll have to wait and grab some more scrap from work on monday.

Pretty fun project so far.


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