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Thread: Rookie DIY project based on 604 hpln

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    Rookie DIY project based on 604 hpln

    I have some questions regarding my project! Its based on 604-HPLN By the way I am a rookie. I am mounting them in 612 cabinet (I know its not perfect in terms of bass extension) but the size of my room combined with my family's sense of aesthetics must be taken into consideration. I have the original crossovers should I use them or replace them with werner jagusch (if... how do I buy from him?) or others please recommend? I have the dimensions of the cabinet but what about the dimensions of the plywood how thick and what about the front baffle is it supposed to be thicker? And does anybody have pictures or drawings of the inside bracing? inside cabling?...recomendations on terminals..should buy specific screws bolts and what size? ok enough with the questions thank you all Best /J

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    Senior Member RMC's Avatar
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    The plans for the 612 cab indicate a 6 cu.ft. box. The material thickness appears to be 3/4" on the plans i have. Good 7-ply Fir plywood should be ok on all panels.

    The diagonal brace on plan for the back panel i guess isn't a good idea even if it comes from Altec. More recent work from D'Appolito and Alden has shown that a diagonal brace is less effective than a straight one. So each brace should divide a panel in two equal parts and placed lengthwise (glued and screwed). You can probably use good 2X2" for bracing.

    An horizontal brace on the baffle between woofer and vent (closer to woofer than vent) is a good idea. You can attach on that horizontal brace a front to back panel brace which is very strong being oriented in the direction of greatest stiffness (can't stretch or compress). Finally, a left to right side panels brace mid way joining the two is also strong for the same direction of greatest stiffness reason. So basically, in addition to each panel being braced, you will also have a cross type bracing (front to back and side to side) taking care of the largest panels which are more prone to vivration. I often use the bracing mentioned here and it works well.

    Regarding the horizontal brace on baffle between woofer and vent i typically use a piece of 1X3" ON EDGE, it takes less space, easy to attach the front to back brace on and minimizes vent air flow issues for nearby vent (braces should not be too close to or in the way of air flowing in/out as much as possible). Regards,

    Richard

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    plans drawings

    Thank you so much I am currently drawing my speakers in 3d. But I would love to see the plans/diagrams you refer to just to make sure my dimensions are allright?

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    This is part of a larger (too large) document to post. I'll try to make a smaller size version of the document. Send me a Private Message with an e-mail address so i can forward the plans directly to you.

    Richard

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    I forgot to mention, since the 612 plans are somewhat old there are no Metric measures on these, only Imperial ones and there's a lot of them, meaning you'll have to do a large amount of conversions to Metric. Still interested in those plans?

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    Always look in the Library 70's Enclosure Plans

    http://www.lansingheritage.org/html/...ltec-plans.htm

    Rob
    "I could be arguing in my spare time"

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    Quote Originally Posted by RMC View Post
    I forgot to mention, since the 612 plans are somewhat old there are no Metric measures on these, only Imperial ones and there's a lot of them, meaning you'll have to do a large amount of conversions to Metric. Still interested in those plans?
    Sorry have been busy but back with the project! thank you so much I would be very interested! If its not to much to ask thanks

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    Senior Member RMC's Avatar
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    I asked you (Post # 4) "Send me a Private Message with an e-mail address so i can forward the plans directly to you."

    You didn't reply and never sent me a message with an e-mail address so i can send this to you. Still waiting...

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    Tuning the enclosure by adjusting the port

    I found a PDF online which explains how to tune Name:  Port.jpg
Views: 137
Size:  145.5 KBthe port for better low frequency and transient response.
    It recommend making a larger port 48.68 square inches? what do you think Should I go for that or stick to the original?
    I am also curious if it's the area that is important and if I can change dimensions of the port?

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    I sent you the 612 plans 2 minutes ago.

    I will answer your other questions in your last post later tonight since i'm busy right now.

    Richard

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    Jon,

    First a bit of history for better understanding about port tuning. In the old days (60's- early 70's) Altec and others tuned their ports based on a woofer's free air resonance (then called cone resonance) and box volume. The results were more or less acceptable but it was the way back then. The science evolved since, for the better, and this is why at the start of your document posted it mentions "... describes a method of improving the low-frequency and transient response ...".

    The enclosure customizing offered, based on more modern principles, is what the document is about, and for your specific case Example #1 from the document addresses your driver/box situation. Basically Altec did the calculations work for you to achieve "preferred results".

    Yes the suggested port area is 48.68 sq. in. RE "go for that or stick to the original?" Personnaly i would follow the improved tuning. You could always tune the box lower but something else will have to give. Downtuning a box to reach lower LF has some negative implications too.

    From what i can see (larger port area) the new tuning tunes the box higher than the old one did, there's probably good reasons for this. Altec engineers determined that in those circumstances 48.68 sq. in. provided the best outcome (compromise) in terms of box size, efficiency, power handling, bandwidth, response and distortion. When designing a cab you always have to balance these things since improving an item or two is generally done at the expense of another.

    RE "if it's the area that is important and if I can change dimensions of the port?"

    Port area (and length) are the important things. The number and shape of port(s) can vary (round, square, rectangular, triangular) but the total area and length must remain the same as Altec suggested. Changing port dimensions could change box tuning and the numbers in the document you posted could change too (Fb, F3, peak, dip, etc.).

    In case you decide to go for a slot type port for example, keep in mind Altec recommends that its dimensions ratio shall not exceed 5 to 1 (long and narrow not good). JBL has a similar note to avoid extreme proportions, but no ratio given.

    I hope the above will help you with your project.

    Richard

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    Thank you so much Richard! I have now designed everything except bracing how does it work and where should I place it? you wrote

    "The diagonal brace on plan for the back panel i guess isn't a good idea even if it comes from Altec. More recent work from D'Appolito and Alden has shown that a diagonal brace is less effective than a straight one. So each brace should divide a panel in two equal parts and placed lengthwise (glued and screwed). You can probably use good 2X2" for bracing.

    An horizontal brace on the baffle between woofer and vent (closer to woofer than vent) is a good idea. You can attach on that horizontal brace a front to back panel brace which is very strong being oriented in the direction of greatest stiffness (can't stretch or compress). Finally, a left to right side panels brace mid way joining the two is also strong for the same direction of greatest stiffness reason. So basically, in addition to each panel being braced, you will also have a cross type bracing (front to back and side to side) taking care of the largest panels which are more prone to vivration. I often use the bracing mentioned here and it works well.

    Regarding the horizontal brace on baffle between woofer and vent i typically use a piece of 1X3" ON EDGE, it takes less space, easy to attach the front to back brace on and minimizes vent air flow issues for nearby vent (braces should not be too close to or in the way of air flowing in/out as much as possible). Regards,"


    My understanding of this is: I should attach a piece of wood 1x3 horizontally right between port and woofer on the backside of the front baffle (going from side to side)? And a brace on each side going from back to front baffle?

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    diameter

    Sorry for spamming this thread but I have one final question where do I find the diameter of the woofer including the frame to know what to mill away. I know the diameter of the hole. In addition to that have a hard time figuring out how to place the screw holes. I want the woofer mounted from the back.

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    Jon,

    I've just sent to your Gmail account an Altec document which i think gives the driver related dimensions you're looking for.

    RE "I should attach a piece of wood 1x3 horizontally right between port and woofer on the backside of the front baffle (going from side to side)?

    YES.

    RE "And a brace on each side going from back to front baffle?"

    I'm not sure you understood correctly. I'll try again. 6 cu.ft. is a relatively large box. Its panels may vibrate as sound level goes up. Each panel should be braced lengthwise (not diagonal) say with a 2X2" glued and screwed (except front panel since already braced with a horizontal 1X3").

    Moreover, the addition of a front to back panels brace (2X2") is also desirable, as well as a left to right panels brace (2X2"). These two form a cross (similar looking to what Jesus was nailed to!). These two further prevent panel expanses at higher level from a large box.

    RE "I want the woofer mounted from the back."

    This is not a good idea. I know in the old days Altec and others did it, but its not a valid reason anymore to continue the practice. The vast majority of drivers today are mounted on the outside of the baffle, not from the inside, for a good reason. If it can be done on the outside this is the preferred way to go.

    The reason being sound diffraction from the edges of the woofer cutout when installed on the inside of box. This is mentioned a number of times in Dickason's Loudspeaker Design Cookbook, 5 th edition, and others. Doing it your way would increase this problem. Why bother to do it then? Also more practical on the outside since you don't have to make a removable back panel for access inside the cab.

    Finally, coaxial drivers have earned a reputation of being lossy drivers (air leaks), therefore you don't need any more losses, which means ALL cab joints must be made air-tight with the use of a sealant such as Silicone, and a soft woofer gasket. Otherwise you may regret it, in the form of a reduction of low frequencies.

    Richard

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    Thanks! I am very gratefull for the replies and all the time spent on helping me out. This image is a screenshot of the 3d model of the speaker. The bracing is visible is it completely wrong?
    Also in terms of the mounting from the back it is inspired by Devon Turnbull's Ojas Speakers and my wife she does not like how the driver looks when its mounted from the front.

    But off course I want to do it right and by your arguments (Richard) it sounds like it is the only way...

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