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Old 19th February 2013, 02:41 AM   #1
wcwc is offline wcwc  United States
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Default Would this work?

From what I read most people who have heard the Mark Audio drivers like them. Most of the people who have heard more than one seem to like the 7.3 the best. Most like to run them with tube amps, including small watt tube amps. I have not heard any of the MA drivers or even tube amps to compare to SS. Due to the low sensitivity of the drivers, they don't get real loud with single digit SET amps.

So since I don't have any experience with them I was wondering if one could build a sealed sub with an 8" driver and set an Alpair 7.3 in a golden ratio mar-Ken enclosure on top. The baffle for the sub would be wider than the Alpair enclosure. Have you ever done this before? I read some of the threads on the FAST systems, but your Woofers were side mounted instead of front mounted. I was thinking of a single speaker with two cavities: one sealed cavity for the sub and one front ported for the Alpair driver. Would this work? I am pretty inexperienced when it comes to speaker design, but while I have seen OB builds like that I have not seen ported/sealed speakers being done that way.

Thanks,

Mike
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Old 19th February 2013, 02:45 PM   #2
wcwc is offline wcwc  United States
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I made a small drawing of my design. Bottom is an 8" self powered sub and the top is a Alpair 7.3 in a golden ratio mar-ken enclosure. Sub is 15" high.

Speaker design.pdf

Last edited by wcwc; 19th February 2013 at 02:48 PM.
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Old 19th February 2013, 04:10 PM   #3
chrisb is offline chrisb  Canada
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Mike - there are numerous ways to approach this, and yours is certainly among them.
Since this query has been posted at the Planet10 forum, I'll feel free to express some of my own thinking on the subject:



Driver height - I'd try to target for the 7.3 be centered between 32-36" from floor (opinions / tastes will vary, but being a short guy, and doing most of my listening in a relaxed sitting position, that's something that works well for me).

Other than the fact that most woofer candidates would be larger than the MarKen enclosure, any particular reason for the tapered shape of the sealed box in your sketch? Dave does have variations of plans for the 7.3 that include a "wide GR", with side exit port slot - it's over 10" wide, which could allow for matching footprint woofer enclosure for up to 8" driver.

Provided you're not constrained by walls to the outside, or large pieces of furniture to the inside, there are some aesthetic advantages to side mounting of either single or multiples of smaller bass drivers. A recent and surprising performing design we've executed consists of 2 little Peerless 4.5 bass drivers (830870) side mounted in a push-push configuration in a column with the same footprint as the little microFonken ( i.e. 158mm wide)

In any case, after a listening session this weekend during which we swapped around several pairs of enclosures with 7.3 and MAOP7, as well as 3 tube and one class T amp, I was reminded of why I like floorstanders; unless you get exotic, less total cost of materials than for a smaller pair and quality speaker stands, and in my case at least, exponentially higher WAF. I'd been living with a pair of EL70 Castle Microtowers for a couple of years, and this weekend gifted them to my mom for her 80th birthday ( a healthy 80 is the new 60, and she's gotta lot of listening years left) Anyway, after swapping them out in our living room with the MAOP7 enclosures, my wife's first question was "when can you build another pair of my speakers?" She is quite happy to keep the EL84 PP tube amp in place.



Back to your case: yup, there's no reason your general approach couldn't work just fine. You could either build as 2 separate enclosures - allows for much greater placement flexibility - or integrate in one.

Have you decided whether you'd like to power the woofers separately, or run passive XO?
My own system uses a single powered cube ( sealed SDX7) mounted behind an end table, dialed in around 100 Hz, with the mains run full range. . I still haven't kludged together a PLLXO for HP, but that would be a good idea.
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Old 19th February 2013, 05:11 PM   #4
wcwc is offline wcwc  United States
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The drivers will be around 36" high. The y will be sitting on a 12" high fireplace mantle. The mantle is 12" deep.

I just came up with the tapered box just for looks to get the baffles to come together. For the sub, I was thinking of using one of the 8" GR servo subs. The plate amp would be mounted on back. I was planning on using a 3.5 W SET stereo amp for the 7.3. May put in a simple high pass filter if I find in necessary. I will use the plate amp to adjust the sub's low pass setting.

Side mounting the bass modules would be a little tricky. Left speaker has equipment rack to one side and Plasma TV to the other. Right speaker has the plasma to the other side.

I figured using the subwoofer as a stand would save me from having to build stands for the monitors. I could just building the subs as rectangles and put the 7.3 speaker on top, but I was concerned about the subs vibration causing issues with speaker on top of it. I guess building them seperate would allow some variation in setup.
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Old 19th February 2013, 07:18 PM   #5
chrisb is offline chrisb  Canada
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Quote:
Originally Posted by wcwc View Post
The drivers will be around 36" high. The y will be sitting on a 12" high fireplace mantle. The mantle is 12" deep.

I just came up with the tapered box just for looks to get the baffles to come together. For the sub, I was thinking of using one of the 8" GR servo subs. The plate amp would be mounted on back. I was planning on using a 3.5 W SET stereo amp for the 7.3. May put in a simple high pass filter if I find in necessary. I will use the plate amp to adjust the sub's low pass setting.

Side mounting the bass modules would be a little tricky. Left speaker has equipment rack to one side and Plasma TV to the other. Right speaker has the plasma to the other side.

I figured using the subwoofer as a stand would save me from having to build stands for the monitors. I could just building the subs as rectangles and put the 7.3 speaker on top, but I was concerned about the subs vibration causing issues with speaker on top of it. I guess building them seperate would allow some variation in setup.

I thought I already posted a response, but here goes again, with an additional comment:

Sounds like you're well on your way to a solution for your particular application.

As to vibrations from the subs causing issues with the mains, unless all boxes are very poorly built, I'd imagine it would be no worse than one could expect to encounter in a "conventional" multi-way incorporating open backed woofers/midrange/tweeters.

If you're planning on using a 3.5W SET for the 7.3s, I'd suggest you definitely consider a HP for them (no higher than 120Hz would be fine). My most favorite sounding amp of the 4 that we used on a session this past weekend was a pair of 2A3 monoblocks ( Bottlehead Paramours) - an absolutely delicious combination, but with the 7.3 in fairly damped 420ft^2 room easily ran into distress. Not so with the 12W EL 84 PP
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Old 19th February 2013, 07:47 PM   #6
wcwc is offline wcwc  United States
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Quote:
Originally Posted by chrisb View Post
I thought I already posted a response, but here goes again, with an additional comment:

Sounds like you're well on your way to a solution for your particular application.

As to vibrations from the subs causing issues with the mains, unless all boxes are very poorly built, I'd imagine it would be no worse than one could expect to encounter in a "conventional" multi-way incorporating open backed woofers/midrange/tweeters.

If you're planning on using a 3.5W SET for the 7.3s, I'd suggest you definitely consider a HP for them (no higher than 120Hz would be fine). My most favorite sounding amp of the 4 that we used on a session this past weekend was a pair of 2A3 monoblocks ( Bottlehead Paramours) - an absolutely delicious combination, but with the 7.3 in fairly damped 420ft^2 room easily ran into distress. Not so with the 12W EL 84 PP
I was looking at building the Bottlehead Stereomour which is an updated stereo amp version of the Paramours. I was going to use my AV receiver to determine the high pass setting for the amp/driver combo. Figuring it would be between 100 and 150 Hz on the high pass filter.
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Old 19th February 2013, 08:07 PM   #7
chrisb is offline chrisb  Canada
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Quote:
Originally Posted by wcwc View Post
I was looking at building the Bottlehead Stereomour which is an updated stereo amp version of the Paramours. I was going to use my AV receiver to determine the high pass setting for the amp/driver combo. Figuring it would be between 100 and 150 Hz on the high pass filter.



If your budget was comfort room for the Stereomour, I don't think you could go wrong. For me the 2A3 is rather like the South American Malbecs - there may be something more expensive and complex out there, but they're relatively affordable, and I've yet to try one I didn't like.

Are planning on using the AV receiver to dial in the appropriate HP point, and then install filters at the Stereomour? If so, you might want to try something I did a few years ago with a pair of Decware Zen C amps used in a bi-amped active system - use the PLLXO calculator found at link below to determine component values, and install them in the amp, along with a second pair of input jacks and toggle switch to bypass for full range.

TLS.org | Passive Line-Level Crossover
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Old 19th February 2013, 09:54 PM   #8
wcwc is offline wcwc  United States
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Quote:
Originally Posted by chrisb View Post
If your budget was comfort room for the Stereomour, I don't think you could go wrong. For me the 2A3 is rather like the South American Malbecs - there may be something more expensive and complex out there, but they're relatively affordable, and I've yet to try one I didn't like.

Are planning on using the AV receiver to dial in the appropriate HP point, and then install filters at the Stereomour? If so, you might want to try something I did a few years ago with a pair of Decware Zen C amps used in a bi-amped active system - use the PLLXO calculator found at link below to determine component values, and install them in the amp, along with a second pair of input jacks and toggle switch to bypass for full range.

TLS.org | Passive Line-Level Crossover
One of the benefits of building your own amp, is that adding a high pass filter to it is doable with out worrying too much about messing up the amp since you know quite a bit about the amp.

Thanks for the link. I will start out running the AVR as the preamp, then disconnect it later since the amp has a volume control.
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Old 9th March 2013, 01:17 AM   #9
wcwc is offline wcwc  United States
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How does the 7.3 behave in a sealed enclosure? What would be the effect of a 10" wide baffle?

I was thinking of making a single speaker with two sealed compartments. One for the sub and one for the Aplair. Just have a single baffle width. 10" would be probably the minimum I could use.
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Old 9th March 2013, 03:44 AM   #10
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How does the 7.3 behave in a sealed enclosure?
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