Hello,
I should have found a pair of CHP-70.2 at less than half of their normal price.
I would like to know which easy build I can do with them.
I've found those that seem quite easy:
https://frugal-phile.com/boxlib/pensils/Pensil10-2-map-211010.pdf
https://frugal-phile.com/boxlib/pensils/PensilP70s3-map.pdf
https://www.markaudio.com/wp-content/uploads/2022/09/CHP-70.2-vented-box-standmount.png
What to expect from those cabinets?
Something else that can be easy to build and well sounding?
Thank you in advance,
Roberto
I should have found a pair of CHP-70.2 at less than half of their normal price.
I would like to know which easy build I can do with them.
I've found those that seem quite easy:
https://frugal-phile.com/boxlib/pensils/Pensil10-2-map-211010.pdf
https://frugal-phile.com/boxlib/pensils/PensilP70s3-map.pdf
https://www.markaudio.com/wp-content/uploads/2022/09/CHP-70.2-vented-box-standmount.png
What to expect from those cabinets?
Something else that can be easy to build and well sounding?
Thank you in advance,
Roberto
Greets!
Well, these are Scott's designs AFAIK, but I'll give my $0.02 worth opinion anyway 😉:
Top two gives a well stuffed/rolled off/over-damped BR-like response of days gone by whereas the third one yields a more late '50s/early '60s era response with a lot more peak SPL down to ~56 Hz with some form of high pass filter needed at rated 20 W, so just depends on what your performance goals are with the understanding that the room dominates in the box's ~56-278 Hz passband.
Since it's designed for mimicking the radio/TV, small HIFI speakers of my youth; if I were to build some it would be a bit smaller tuned to Fs*, with a more rolled off LF same as the first two once the vent is critically damped (attached) for low group delay (very low/below most folk's hearing acuity 'ringing') with some form of high pass filter at rated 20 W with some form of zero feedback amp.
* 'Classic' BR: ~3.26 L net, 3.5 cm dia. x 14 cm L vent
Well, these are Scott's designs AFAIK, but I'll give my $0.02 worth opinion anyway 😉:
Top two gives a well stuffed/rolled off/over-damped BR-like response of days gone by whereas the third one yields a more late '50s/early '60s era response with a lot more peak SPL down to ~56 Hz with some form of high pass filter needed at rated 20 W, so just depends on what your performance goals are with the understanding that the room dominates in the box's ~56-278 Hz passband.
Since it's designed for mimicking the radio/TV, small HIFI speakers of my youth; if I were to build some it would be a bit smaller tuned to Fs*, with a more rolled off LF same as the first two once the vent is critically damped (attached) for low group delay (very low/below most folk's hearing acuity 'ringing') with some form of high pass filter at rated 20 W with some form of zero feedback amp.
* 'Classic' BR: ~3.26 L net, 3.5 cm dia. x 14 cm L vent
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I have build the CGR from
frugal-phile.com .
Its a proven design. From my point of view they play quite low. The bass is lovely. Deep and articulated. I use them to listen to some specific electronik music where they perform well.
They play in a small room. Acoustic stuff is ofc no problem.
frugal-phile.com .
Its a proven design. From my point of view they play quite low. The bass is lovely. Deep and articulated. I use them to listen to some specific electronik music where they perform well.
They play in a small room. Acoustic stuff is ofc no problem.
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Hmm, at this size, might as well add another 0.9 L net to it and shorten the vent to 14.1 cm for a T/S max flat for a bit more (mid) bass.
One is ~1.294 ft^3 gross, the other ~2.404 ft^3, which will have more lower bass BW, though less power handling since we're always trading efficiency for BW.
Pensil P70 is designed for the CHP-70.2. Pensil 10.2 was designed for the long-defunct Apair 10.2, which was a completely different & significantly larger driver (about 75%). For the intended unit (don't use anything else in it), it had a slightly different target alignment to most of the other pensils, which was an experiment I wasn't especially happy with, since it typically needed a greater damping density. The pensil for the current generation Alpair 10.3 was re-jigged, with a slightly different alignment despite sharing the same [more or less] Vb.
I do apologize for the neophite question, but would it be possible to adapt the Pensil P70 as follows?
Thanks!
Roberto
- Maintain the same center-of-the-speaker to center-of-the-slot/venting at 740-18-16 = 706 mm;
- Have the speaker at the center of the front baffle: 740 mm from bottom and 740 mm from top;
- Maintain the same baffle width;
- Scale the depth of the cabinet to keep the same internal volume, so 163 mm internal, 199 external.
- Have two slots/ventings, one on top one on bottom of the front baffle, with an height of 16 instead of 32mm.
Thanks!
Roberto
One more information: what is the expected bandwidth with the P70 cabinet?
I’m thinking to gift those speakers for Christmas to a friend who’s wife likes alot audiobooks (CHP70.2 are perfect for this AFAIK), and who’s two young sons would start to listen to music.
A bluetooth TA2024 amp could be the most used amp, both for the simplicity (every smartphone can be connected in a while) and for the rated power (around 15-20 Wrms per channel).
Will the low Zout of the class D amp be a problem for the design of those speakers-cabinet?
I’m thinking to gift those speakers for Christmas to a friend who’s wife likes alot audiobooks (CHP70.2 are perfect for this AFAIK), and who’s two young sons would start to listen to music.
A bluetooth TA2024 amp could be the most used amp, both for the simplicity (every smartphone can be connected in a while) and for the rated power (around 15-20 Wrms per channel).
Will the low Zout of the class D amp be a problem for the design of those speakers-cabinet?
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Re the first five:
1/ & 2/ Unfortunately not: in MLTLs (which the pensils are a specific variation of), the physical dimensions & locations of the driver, vent etc. are functional parts of the alignment, unlike BR / later vented boxes which are based purely on Helmholtz resonance.
3 & 4/ I'm not sure I'm following (apologies, I've not had much sleep). If you maintain the baffle width, you can't hold Vb static if you alter the depth, unless height is also changed, in which case points 1/ & 2/ above come into effect
5/ I'm afraid not, for the reasons described above.
Re the amplifier, it shouldn't be an issue for any of mine, or the classic ducted vent box alignment GM suggested. Unless I mention it on the sketches, the MA boxes I've designed always assume a voltage source (low output impedance / high DF), albeit usually assuming about 1/2ohm of [speaker] wire loop resistance & some connection losses. I've done a handful where a higher output impedance is assumed, but I always state on the sketches when that applies, or things could go pear-shaped. 😉
1/ & 2/ Unfortunately not: in MLTLs (which the pensils are a specific variation of), the physical dimensions & locations of the driver, vent etc. are functional parts of the alignment, unlike BR / later vented boxes which are based purely on Helmholtz resonance.
3 & 4/ I'm not sure I'm following (apologies, I've not had much sleep). If you maintain the baffle width, you can't hold Vb static if you alter the depth, unless height is also changed, in which case points 1/ & 2/ above come into effect
5/ I'm afraid not, for the reasons described above.
Re the amplifier, it shouldn't be an issue for any of mine, or the classic ducted vent box alignment GM suggested. Unless I mention it on the sketches, the MA boxes I've designed always assume a voltage source (low output impedance / high DF), albeit usually assuming about 1/2ohm of [speaker] wire loop resistance & some connection losses. I've done a handful where a higher output impedance is assumed, but I always state on the sketches when that applies, or things could go pear-shaped. 😉
UPDATE: at the end the seller decided not to sell those speakers.
Once in a while a used pair of Mark Audio comes out on national sites. That's how I got the two MA 10.3 for the Silbury.
I will take a look for other speakers in the near future (after Christmas is usually a good period).
Once in a while a used pair of Mark Audio comes out on national sites. That's how I got the two MA 10.3 for the Silbury.
I will take a look for other speakers in the near future (after Christmas is usually a good period).
