Cabinet Design for Altec 414z's - Page 3

buzzforb · 4th January 2013, 10:21 PM

GM,
You got cab dimensions on this one. Stilll have a pair of 414's to pair with 806's

vinylnvalves · 5th January 2013, 05:03 PM

GM

AOT = adjust on test

" Well, the MLTL is a simple to design/build/tweak, higher sound quality [SQ] vented alignment, so hard to go wrong with it IF it meets the needs of the app" Your statement corcerns me, what is the downside of the MLTL ? ( My assumption was if the onken works for me then should be similar with better LF, based on your comments.

Just reading into what your saying, i just make the cabinet as big as possible with a TL around 62" and tune the port to get what i want.

Would it not be possible to use a non rectangular cabinet ...

Whats the issues with expanding MLTL as i have seen a number on the web, and lends itsself better to the cabinet shape i propose.

I need to get MJK software up and running so i can simulate, i assume port location and room effects need to be accounted for?

Have some particle board i was goint to knock up a test cabinet, so i can experiment with port and driver location etc. Can initially make a simple rectangular cabinet to see how the MLTL integrates with the horns, so a good starting point would be appreciated.

I noticed someone putting a Karlson type port on their MLTL i assume that this is not the right thing to do?

On the topic of cleaning the altec surrounds - is a tooth brush to stiff to move the doping around with?

dumptruck · 5th January 2013, 07:55 PM

I don't think literally "as big as possible" is going to be right for a 414 - you'll run out of excursion eventually.

vinylnvalves · 5th January 2013, 10:13 PM

That was a figure if speech, obviously if space wasn't an issue, i would probably be considering a front loaded horn. I am wondering if something like the Edgar "show horn" may be an alternative to whats being discussed. With my space constraints this would be limited to around 45 hz, assuming i get help from the corners of the room.

GM · 6th January 2013, 10:59 PM

Quote:

Originally Posted by buzzforb

GM,
You got cab dimensions on this one. Stilll have a pair of 414's to pair with 806's

I already posted all the pertinent dims except I forgot the vent location, which is
~12.2" up from the back bottom.

GM

vinylnvalves · 7th January 2013, 09:49 PM

Do we take it as a 48" long column, CSA = 288 inches, with the vent 12.2" from the bottom, if so, sorry i missed where the driver is located from the top then.

vinylnvalves · 28th January 2013, 07:57 PM

Got around to measuring the 414'z. Using the -6db approach i got the following for one of the drivers

fs=38hz qms=3.0 qes=0.25 and qts=0.23 Vas=160 ltrs Re=11.2 ohms ( the VAS determined this using a closed volume, adding weight method gave me 466 ltrs - quoted Altec spec was 256ltrs so not close with either approach.)

Not as close as i was expecting, but then again they are 47 years old. I may try cleaning the goop off the surround and then remeasure to see what changes.

vinylnvalves · 7th June 2013, 07:38 PM

Long time doing other things, starting to look at the cabinets again. Managed to get the fs down to 35hz by cleaning the surrounds with some MEK (well really redistributing it). Started looking at the MLTL cabinet again for these drivers. Managed to find my account details for MJK's site and software so was going to try replicating GM's simulation in Mathcad, unfortunately my student version of mathcad doesn't seem to load anymore, and don't feel like paying out again for it.

Reason i wanted to simulate it isn't i wanted to second guess GM but was looking at making the cabinet a little taller @ 36" ( better for the TPL) and was going to attempt to work out what i needed to change. I was going to keep Vb the same and adjust the CSA down accordingy for the extra 4" of height.

Initially my throughts are to knock together a simple cabinet from particle board adding the flexibility to move the port location so i can fine tune.

One thing i was musing with is can the Decca corner horn approach of having reasonant cabinet panels to damp the harmonics as suggested by Ralph West be used to minimise internal stuffing used with MLTL's or is this an idea from the 1960's best ignored?

Greebster · 8th June 2013, 02:59 AM

Tho not as accurate as MJK's speadsheets, Transmission Line v.3.6.1.14 does a nice job. Known to be accurate from ~80-200Hz. Above 200 the resonances are greatly lifted in amplitude and below 80 response is reduced by 6-8dB @20Hz. Take this into consideration and it works quite well.

Here is the diy thread

vinylnvalves · 9th June 2013, 12:49 PM

Thanks for that. I tried loading it, without success, issues loading the MS framework needed to run it. This could be why my copy of mathcad doesn't work. May ask one of the offspring if i can borrow one of their more upto date laptops (that i bought anyway) and see if it works on that.

4th January 2013, 10:21 PM	#21
buzzforb diyAudio Member Join Date: Oct 2010 Location: Burlington, NC	GM, You got cab dimensions on this one. Stilll have a pair of 414's to pair with 806's __________________ \|F6 Kit/Trasnformer GB Sign up sheet Closed,\|Primrose GB Sign Up sheetClick Here ...Shape the sound , Man!

8th June 2013, 02:59 AM	#29
Greebster diyAudio Member Join Date: Aug 2010 Location: South of the Skyway	freebie TL software Tho not as accurate as MJK's speadsheets, Transmission Line v.3.6.1.14 does a nice job. Known to be accurate from ~80-200Hz. Above 200 the resonances are greatly lifted in amplitude and below 80 response is reduced by 6-8dB @20Hz. Take this into consideration and it works quite well. Here is the diy thread

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5th January 2013, 05:03 PM	#22
vinylnvalves diyAudio Member Join Date: Dec 2008	GM AOT = adjust on test " Well, the MLTL is a simple to design/build/tweak, higher sound quality [SQ] vented alignment, so hard to go wrong with it IF it meets the needs of the app" Your statement corcerns me, what is the downside of the MLTL ? ( My assumption was if the onken works for me then should be similar with better LF, based on your comments. Just reading into what your saying, i just make the cabinet as big as possible with a TL around 62" and tune the port to get what i want. Would it not be possible to use a non rectangular cabinet ... Whats the issues with expanding MLTL as i have seen a number on the web, and lends itsself better to the cabinet shape i propose. I need to get MJK software up and running so i can simulate, i assume port location and room effects need to be accounted for? Have some particle board i was goint to knock up a test cabinet, so i can experiment with port and driver location etc. Can initially make a simple rectangular cabinet to see how the MLTL integrates with the horns, so a good starting point would be appreciated. I noticed someone putting a Karlson type port on their MLTL i assume that this is not the right thing to do? On the topic of cleaning the altec surrounds - is a tooth brush to stiff to move the doping around with?

5th January 2013, 07:55 PM	#23
dumptruck diyAudio Member Join Date: May 2010 Location: MN	I don't think literally "as big as possible" is going to be right for a 414 - you'll run out of excursion eventually.

5th January 2013, 10:13 PM	#24
vinylnvalves diyAudio Member Join Date: Dec 2008	That was a figure if speech, obviously if space wasn't an issue, i would probably be considering a front loaded horn. I am wondering if something like the Edgar "show horn" may be an alternative to whats being discussed. With my space constraints this would be limited to around 45 hz, assuming i get help from the corners of the room.

7th January 2013, 09:49 PM	#26
vinylnvalves diyAudio Member Join Date: Dec 2008	Do we take it as a 48" long column, CSA = 288 inches, with the vent 12.2" from the bottom, if so, sorry i missed where the driver is located from the top then.

28th January 2013, 07:57 PM	#27
vinylnvalves diyAudio Member Join Date: Dec 2008	Got around to measuring the 414'z. Using the -6db approach i got the following for one of the drivers fs=38hz qms=3.0 qes=0.25 and qts=0.23 Vas=160 ltrs Re=11.2 ohms ( the VAS determined this using a closed volume, adding weight method gave me 466 ltrs - quoted Altec spec was 256ltrs so not close with either approach.) Not as close as i was expecting, but then again they are 47 years old. I may try cleaning the goop off the surround and then remeasure to see what changes.

7th June 2013, 07:38 PM	#28
vinylnvalves diyAudio Member Join Date: Dec 2008	Long time doing other things, starting to look at the cabinets again. Managed to get the fs down to 35hz by cleaning the surrounds with some MEK (well really redistributing it). Started looking at the MLTL cabinet again for these drivers. Managed to find my account details for MJK's site and software so was going to try replicating GM's simulation in Mathcad, unfortunately my student version of mathcad doesn't seem to load anymore, and don't feel like paying out again for it. Reason i wanted to simulate it isn't i wanted to second guess GM but was looking at making the cabinet a little taller @ 36" ( better for the TPL) and was going to attempt to work out what i needed to change. I was going to keep Vb the same and adjust the CSA down accordingy for the extra 4" of height. Initially my throughts are to knock together a simple cabinet from particle board adding the flexibility to move the port location so i can fine tune. One thing i was musing with is can the Decca corner horn approach of having reasonant cabinet panels to damp the harmonics as suggested by Ralph West be used to minimise internal stuffing used with MLTL's or is this an idea from the 1960's best ignored?

9th June 2013, 12:49 PM	#30
vinylnvalves diyAudio Member Join Date: Dec 2008	Thanks for that. I tried loading it, without success, issues loading the MS framework needed to run it. This could be why my copy of mathcad doesn't work. May ask one of the offspring if i can borrow one of their more upto date laptops (that i bought anyway) and see if it works on that.