***Desktop Speakers***

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Danny Richie

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Re: ***Desktop Speakers***
« Reply #100 on: 23 Mar 2012, 11:42 pm »
But those responses look identical.   I'm still confused.

Okay Larry,

I have copied the Blue line from the second graph (with the in line inductor) onto the first graph. Now do you see the difference in the two blue lines?



Peter J

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Re: ***Desktop Speakers***
« Reply #101 on: 23 Mar 2012, 11:58 pm »
But those responses look identical.   I'm still confused.

Larry, they look similar, but in the second graph the upper woofer (lowest on graph...dark blue) starts falling off a little sooner, around 800 Hz.

 I'm actually getting to the point that I recognize a little more of what I'm looking at! The phase and wavelength thing still befuddle me...oh well.


Danny, I have to say that from my limited knowledge, moving that woofer forward made a significant difference, no?

I'm game to try the tweeter, do you have a recommendation?

While I appreciate your candor when you ask us,"Okay, how's this" ,  I sure don't feel qualified to say, " well Danny, that looks great!". Having  just gotten my yellow belt in speaker design and all :) I know just enough to be dangerous!


 

 

Danny Richie

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Re: ***Desktop Speakers***
« Reply #102 on: 24 Mar 2012, 12:26 am »
Quote
Danny, I have to say that from my limited knowledge, moving that woofer forward made a significant difference, no?

Yes it did.

And the response is very smooth.

You can use just about anything for a rear ambiance tweeter. It is only going to add a little air in the very top end. So just about any inexpensive dome tweeter would be good.

LarryB

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Re: ***Desktop Speakers***
« Reply #103 on: 24 Mar 2012, 12:52 am »
Danny:

Absolutely, the thick blue lines are quite different.  But you said before those were the lower woofers, which is why I got confused:


Quote
Blue is the lower one

Larry

Peter J

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Re: ***Desktop Speakers***
« Reply #104 on: 24 Mar 2012, 01:17 am »
Yes it did.

And the response is very smooth.

You can use just about anything for a rear ambiance tweeter. It is only going to add a little air in the very top end. So just about any inexpensive dome tweeter would be good.

Perhaps AV123 stuff, like what the X-LS has, or would that be overkill?

Mounted up near the top on rear, that's a lot of holes cut in a small area, do you think it would be wise to look at smaller diameter or maybe lower mounting?

Danny Richie

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Re: ***Desktop Speakers***
« Reply #105 on: 24 Mar 2012, 01:48 pm »
Danny:

Absolutely, the thick blue lines are quite different.  But you said before those were the lower woofers, which is why I got confused:


Larry

Oh, sorry about that.

Perhaps AV123 stuff, like what the X-LS has, or would that be overkill?

Mounted up near the top on rear, that's a lot of holes cut in a small area, do you think it would be wise to look at smaller diameter or maybe lower mounting?

High mounting is fine.

LarryB

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Re: ***Desktop Speakers***
« Reply #106 on: 24 Mar 2012, 04:20 pm »
Apology accepted.  Someone's gotta' keep you on your toes. :)

Peter J

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Re: ***Desktop Speakers***
« Reply #107 on: 24 Mar 2012, 09:32 pm »


Another thought on this is that a rear firing ambiance tweeter could be added with a single small cap and resistor (adjustable) to give it back a little air. That will help with the over all sound since the top end is a little soft. It would also not effect the on axis response, just the overall in room response and balance. It will also lower the impedance in the top end and balance the impedance load.   


Danny, when you say adjustable, I'm assuming changing value of cap and resistor accomplishes the adjustment, correct? Where does one start with these values?


Danny Richie

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Re: ***Desktop Speakers***
« Reply #108 on: 24 Mar 2012, 10:00 pm »
Danny, when you say adjustable, I'm assuming changing value of cap and resistor accomplishes the adjustment, correct? Where does one start with these values?

The cap value will be pretty small to match the rear wave output. Then the level of the tweeter can be adjusted up or down via the resistor value.

Peter J

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Re: ***Desktop Speakers***
« Reply #109 on: 27 Mar 2012, 02:53 am »
Question for those following this thread, (assuming any are still hangin' in!).

 I'm soon to build a finished pair...pretty basic, with laminate as the final finish. Maybe mess with a rear tweeter later. If there's interest, I'll shoot pics along the way. What say you?

skeeter99

Re: ***Desktop Speakers***
« Reply #110 on: 27 Mar 2012, 03:04 am »
Question for those following this thread, (assuming any are still hangin' in!).

 I'm soon to build a finished pair...pretty basic, with laminate as the final finish. Maybe mess with a rear tweeter later. If there's interest, I'll shoot pics along the way. What say you?

I'm still following and would love more pics! I'm getting ready to cut holes in my towers :-)

DeeJayBump

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Re: ***Desktop Speakers***
« Reply #111 on: 27 Mar 2012, 03:38 am »
Absolutely, keep us updated with pics.

Thanks.

Plund

Re: ***Desktop Speakers***
« Reply #112 on: 27 Mar 2012, 04:30 am »
More pics please!  Thanks for sharing your expertise!

Pete

Peter J

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Re: ***Desktop Speakers***
« Reply #113 on: 29 Mar 2012, 11:19 pm »
Here we go...

Parts cut out. I tried to make constuction simple so design could be easily duplicated. All butt joints and glue.




Sides and top glued and clamped, bottom left loose and used as a spacer




Glue and clamp front and back, bottom still loose, you'll see why...




Danny's Bass Box calcs called for two 1/2" dia. x 7/16" long ports. conversion to single port for same volume ended up with odd hole size that most people won't likely have, so this was path of least resistance. Removing material from inside to accomplish the 7/16" dimension in 1/2" material.




Before and after




Ready to clamp front and rear on. I did both at the same time, but might be easier one at a time if it's new to you.




Clamped




All flush trimmed and putting stop cleats in for bottom to land on




Speaker and base the same except base has 3/4" top and bottom





Next up laminating exteriors, stuffing interiors and final assembly...stay tuned!



« Last Edit: 30 Mar 2012, 12:22 am by Peter J »

Mr. Oczka

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Re: ***Desktop Speakers***
« Reply #114 on: 29 Mar 2012, 11:43 pm »
Wow, the cabinets are looking great!  I have thoroughly enjoyed following this thread!  Actually, your project has pushed me into giving it a try.  The low cost of these drivers makes it pretty easy too.

Can you post the dimensions of your cabinets?  I want to try to duplicate it.

Also, just curious, are you going to stain the cabinets or paint them?

Thanks again, Tom 

Peter J

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Re: ***Desktop Speakers***
« Reply #115 on: 30 Mar 2012, 01:03 am »
Wow, the cabinets are looking great!  I have thoroughly enjoyed following this thread!  Actually, your project has pushed me into giving it a try.  The low cost of these drivers makes it pretty easy too.

Can you post the dimensions of your cabinets?  I want to try to duplicate it.

Also, just curious, are you going to stain the cabinets or paint them?

Thanks again, Tom

Tom, I'm posting a some graphics that will give dimensions...hopefully all you need. I varied the base height from that shown to 8 3/4" because I wanted the front drivers to peek over my monitor...you'll see what I'm saying as I post more on this thread.

A few  things to bear in mind;

The base has no function other than to raise the speaker, so it can be eliminated if you like.

If you want the whole Sketchup model, I can email it to you, shoot me a PM with your email addy and it's yours, and that goes for anyone else as well. Google has a free version of Sketchup that will (I'm pretty sure) open this and give you most if not all the capability I used to draw it. It's very cool and capable and FREE, so have fun.

 http://sketchup.google.com/intl/en/download/


To make this build even easier, I think one could eliminate the rabbet for the driver flange to get them flush with cabinet without huge detriment to overall sound. Danny, can you speak to that?





Finish will be this laminate,

http://samples.wilsonartcontract.com/p-517-xanadu-7945.aspx

 which is the same as I put on the receiver in this thread.

http://www.audiocircle.com/index.php?topic=104835.0


Let me know if there's something else that I've overlooked. Let's get those things started!


 

Mr. Oczka

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Re: ***Desktop Speakers***
« Reply #116 on: 30 Mar 2012, 02:46 am »
pm sent.

Thanks,
Tom

Danny Richie

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Re: ***Desktop Speakers***
« Reply #117 on: 30 Mar 2012, 03:24 am »
Quote
To make this build even easier, I think one could eliminate the rabbet for the driver flange to get them flush with cabinet without huge detriment to overall sound. Danny, can you speak to that?

You could probably get away with not flush mounting the top driver, but if you did that to the front facing one then it would add a little ripple to the response.

Peter J

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Re: ***Desktop Speakers***
« Reply #118 on: 31 Mar 2012, 12:38 am »
Moving on with laminating and stuffing...


Parts ready, laminate cut to size




Contact on opposite sides




Ready to trim




And a little painting, you'll see why




Speaker cutout template, double sided tape 'cuz it's hard to clamp




Round-under bit for holes




Some black dye so there's no light showing




Lined with "horse hair" felt




Stayed back some  from drivers so airflow isn't impeded




And poly fill. Danny does this look like what you had in mind?















Peter J

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Re: ***Desktop Speakers***
« Reply #119 on: 31 Mar 2012, 01:02 am »
Approaching the end...

Inductors glued to bottoms




soldering inductor to upper driver positive side




Solder to binding post




Screwed risers to speakers




Sand baggie for ballast, the little drivers are hefty, so they're a little top heavy. Never really liked the look of plinths




Riser bottom installed, gettin' close




The vanity shot




Backside shot





And the obligatory installed shot





Listening to the Prentenders "The Isle of View", Chrissie's sounding fine...