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Pi seven port size using Altec 421A 15" Drivers [message #42970]

Sun, 09 November 2003 11:45

jumpin
Messages: 3
Registered: May 2009

Esquire

I am building a pair of Pi Sevens using altec 421A 15" 8ohm drivers. Could someone advise on correct port lenght and dia. Any advice on bracing would also be helpful. I am using 18mm MDF.

Cheers Jumpin

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Re: Pi seven port size using Altec 421A 15" Drivers [message #42971 is a reply to message #42970]

Sun, 09 November 2003 14:41

Wayne Parham
Messages: 18791
Registered: January 2001

Illuminati (33rd Degree)

According to "Great Plains Audio," Altec specs for the 421-8H are as follows:

Vas = 12.8ft3
Fts = 32Hz
Qts = 0.25

Based on these values, PiAlign recommends a 3.2ft3 cabinet tuned to 48Hz using a port that's 7.5" long, 4.6" tall and 8.2" wide.

Response is nice and flat with 60Hz f3 and 40Hz f10.

If this isn't the driver you have, you might consult the Altec T/S Specifications chart at Great Plains Audio to obtain the specs you need.

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Re: Pi seven port size using Altec 421A 15" Drivers [message #42972 is a reply to message #42970]

Sun, 09 November 2003 17:53

Manualblock
Messages: 4973
Registered: May 2009

Illuminati (13th Degree)

Hi; What hf driver will you be using if I may ask, Only because I use the 421 in an 4.2cu.ft. enclosure base reflex tiangular shape with an 811/806 on top and the stock 800 hz. xo and would be interested in your chioce of hf.

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If I am not mistaken... [message #42998 is a reply to message #42972]

Tue, 11 November 2003 18:36

Shanko
Messages: 15
Registered: May 2009

Chancellor

..I think Jumpin is using another big round tractrix (Oris variant) loaded with PM2A's. Crossover around 140 hz. He hasn't answered because he is cutting panels for his 7Pi's!

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