"Baby Lab" is short form for Scott's series of compact Onley inspired folded labyrinth. As Dave mentioned, over the past year or so we've experimented and refined details using this format for at least 5 models by Fostex, MarkAudio, Fountek, and Aura - I've built all but the Aura
Drawings not quite ready for release.
When I say compact, a single 4x8 sheet would yield at least 3 pr, including all the internal panels
Drawings not quite ready for release.
When I say compact, a single 4x8 sheet would yield at least 3 pr, including all the internal panels
Thanks for the replies.
Looks like I chose the wrong design - should have checked here before committing myself
From further listening, it's clear that I'm not going to get the required bass from this combination.
Adding in my passive woofers and active sub really transforms the sound into something approaching very nice.
The Pensils are pretty huge in the context of my room, so it's a shame that the size doesn't add anything useful except put the drivers at the correct height.
So, my thinking is to either:
1. Use the drivers in a new mini enclosure that can sit on my existing stands.
or
2. modify the pensils to make a smaller enclosure within the pensil enclosure (sealed or BR or other) with internal bulkheads - perhaps I can then add some passive woofers into the bottom half of the enclosure?
What do you think?
Cheers,
Martin
Looks like I chose the wrong design - should have checked here before committing myself
From further listening, it's clear that I'm not going to get the required bass from this combination.
Adding in my passive woofers and active sub really transforms the sound into something approaching very nice.
The Pensils are pretty huge in the context of my room, so it's a shame that the size doesn't add anything useful except put the drivers at the correct height.
So, my thinking is to either:
1. Use the drivers in a new mini enclosure that can sit on my existing stands.
or
2. modify the pensils to make a smaller enclosure within the pensil enclosure (sealed or BR or other) with internal bulkheads - perhaps I can then add some passive woofers into the bottom half of the enclosure?
What do you think?
Cheers,
Martin
Hi,
if you are using brand new drivers I would suggest to wait some time for a final decision and let the drivers break in.
I just built a couple of weeks ago a pair of microMarken6 with alpair 6.2m;
it is a very small cabinet (3liters) and I was completelly disappointed by the bass extension. Day by day, I am getting more and more satisfied: yesterday evening I realized, by using a tone generator, that the small boxes return clearly earable sound at 50hz (obviously not flat but there).
Ok, they are not the right speakers for listening to the London Symphony Orchestra or Gun's Roses, but in a medium-small room and small ensemble music I see no need for extra bass.
northernsky
Martin: to echo northernsky (and my own earlier note), you can expect some overall improvement after the rather lengthy break-in, but it won't be a life changing experience.
Due to the limited floorspace seen in your photo for additional woofer enclosures, and the time/materials invested in the Pensils, if you still find them lacking after break-in, I'd be inclined to modify them, and add small woofers to turn them into a 2-way system. I personally like XO below the telephone band, but that tends to make component values for passive filters rather large, and costly if using films, etc. First candidate driver I can think of would be one of the 6" SilverFlutes or locally available equivalent, mounted on side panel.
Before that, though - would there be an opportunity to test these enclosures in an entirely different system - say a friend / relative's? It's always nice to isolate a problem / confirm the diagnosis before attempting a cure.
Due to the limited floorspace seen in your photo for additional woofer enclosures, and the time/materials invested in the Pensils, if you still find them lacking after break-in, I'd be inclined to modify them, and add small woofers to turn them into a 2-way system. I personally like XO below the telephone band, but that tends to make component values for passive filters rather large, and costly if using films, etc. First candidate driver I can think of would be one of the 6" SilverFlutes or locally available equivalent, mounted on side panel.
Before that, though - would there be an opportunity to test these enclosures in an entirely different system - say a friend / relative's? It's always nice to isolate a problem / confirm the diagnosis before attempting a cure.
Hi Chris and Northernsky,
Thanks for your input. I'm going to run them in over the xmas period in the spare room - 18 hours a day for 2 weeks should loosen them up a bit! After that, i'll spend time playing with the stuffing, sources and amplifiers.
I do have another amp to hand - a 1980s Cambridge audio unit with plenty of power and a lovely silky smooth, weighty balance. And then I've also got my HT setup downstairs to try.
@northernsky, the Pensils have almost the same width and depth dimensions as your microMarkens. Would just need to saw ~600mm off the bottom and form the port et voila! What sort of amplification are you using with yours?
Cheers,
Martin
Thanks for your input. I'm going to run them in over the xmas period in the spare room - 18 hours a day for 2 weeks should loosen them up a bit! After that, i'll spend time playing with the stuffing, sources and amplifiers.
I do have another amp to hand - a 1980s Cambridge audio unit with plenty of power and a lovely silky smooth, weighty balance. And then I've also got my HT setup downstairs to try.
@northernsky, the Pensils have almost the same width and depth dimensions as your microMarkens. Would just need to saw ~600mm off the bottom and form the port et voila!
What sort of amplification are you using with yours?Cheers,
Martin
300-3k.
No reason the driver can't be front mounted. The side does allow a larger driver.
First thing needed is to figure out the volume remaining once the box is divided into 2. Likely the easiest way to do that is to mount a PVC or cardboard cyclinder behind the A6.
dave
They are a Christmas gift, I am currently testing them with a 12 Watt valve amplifier (M84 by Yarland).
northernsky
Interesting stuff. To me, the good small drivers are the FF85wk, Alpair 7.3 and possibly the new Alpair 7P. Will these 2 larger 4" drivers also work in the CHN70 cabinet ?
I knew that something like this was coming.Thank you Scott for reminding us a good approach/advice on extracting the best from each driver, but most of all a big thank you for the many designs that you have done (with help from Dave, Chris, Mark, etc).
Please don't groan. I'm sure there is enough room to release a dedicated baby lab for an A7.3 and especially the new A7p. There is no doubt plenty of interest in this new driver and many will be stuffing it into some kind of box. A new folded MLTL bookshelf, labyrinth, or baby lab, whatever you want to call it would probably be just the ticket to try it out.
Hello and Happy New Year to you all!
Finally got back to my partially run-in A6m pensils and am beginning to appreciate their charms. They are certainly an easy listen and really get my foot tapping, which is my unscientific way of telling if I like them or not
So, my plan is to forget about the LF extension and use them with my active sub, crossing over at about 120hz.
What I'd like to do is partition off the pensil enclosure to form a smaller sealed or ported box within the pensil box. Later I'll either cut the pensils down to make a pair of small stand mounters or add a helper woofer to the bottom section.
My question is, if I put a plastic tube behind the A6m or a couple of 18mm ply partitions inside, what is the ideal/optimal box size for this driver?
e.g. If I put a 120mm dia PVC tube behind the driver and seal it, I'll get a volume of only around 1.6 litres, less the volume of the driver itself. Seems a bit small?
Any ideas?
Martin
Finally got back to my partially run-in A6m pensils and am beginning to appreciate their charms. They are certainly an easy listen and really get my foot tapping, which is my unscientific way of telling if I like them or not
So, my plan is to forget about the LF extension and use them with my active sub, crossing over at about 120hz.
What I'd like to do is partition off the pensil enclosure to form a smaller sealed or ported box within the pensil box. Later I'll either cut the pensils down to make a pair of small stand mounters or add a helper woofer to the bottom section.
My question is, if I put a plastic tube behind the A6m or a couple of 18mm ply partitions inside, what is the ideal/optimal box size for this driver?
e.g. If I put a 120mm dia PVC tube behind the driver and seal it, I'll get a volume of only around 1.6 litres, less the volume of the driver itself. Seems a bit small?
Any ideas?
Martin
I just made a simulation using winISD and the optimum vented enclosure looks to be 3.9 litres with a single port dia 25mm x 65mm long.
If I put 2 bulkheads in the pensil 6 enclosure, 200mm apart, I should get to 3.9 litres.
Do I need to compensate for the driver and port volumes?
Do the above figures look about right? I also have tuning frequency of 66.97 Hz and Ql of 7.00. There's also vent match of 0.13.
Cheers,
Martin
If I put 2 bulkheads in the pensil 6 enclosure, 200mm apart, I should get to 3.9 litres.
Do I need to compensate for the driver and port volumes?
Do the above figures look about right? I also have tuning frequency of 66.97 Hz and Ql of 7.00. There's also vent match of 0.13.
Cheers,
Martin
Greets!
Different programs calculate different alignments depending on several things, so having a 'bigger is better' [BIB] philosophy, the largest I get is ~4.716 L net/61.85 Hz Fb using the published Mmd, Cms, BL in lieu of Fs, Qes, Cms, Qts for Hornresp to calculate a bit more technically correct set of specs:
Fs = 61.38 Hz
Qes = 0.46
Qts = 0.4
Vas = 4.85 L
Factoring in a 2nd order 120 Hz high pass and a ~14 W acceptable THD limit, the vent can be reduced to 19 mm diameter x ~33 mm long.
Note that <5% vent mach is the goal, though 10% for subsis often good enough for most folks.
Yes, ideally the volume of the driver, vent, bracing, etc., should be added to the calculated net cab volume [Vb].
GM
Different programs calculate different alignments depending on several things, so having a 'bigger is better' [BIB] philosophy, the largest I get is ~4.716 L net/61.85 Hz Fb using the published Mmd, Cms, BL in lieu of Fs, Qes, Cms, Qts for Hornresp to calculate a bit more technically correct set of specs:
Fs = 61.38 Hz
Qes = 0.46
Qts = 0.4
Vas = 4.85 L
Factoring in a 2nd order 120 Hz high pass and a ~14 W acceptable THD limit, the vent can be reduced to 19 mm diameter x ~33 mm long.
Note that <5% vent mach is the goal, though 10% for subsis often good enough for most folks.
Yes, ideally the volume of the driver, vent, bracing, etc., should be added to the calculated net cab volume [Vb].
GM
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