Excellent! Please pass on my thanks to Dr. Lindgren.
EDIT: Actually, I am now quite confused.
If I hold vent diameter at 3" (as it is for EL70 in microTower) and reduce length to 1-5/8", the box tuning goes way up to 70-ish Hz (right at driver Fs) and the gain graph has a huge hump.
If I change the port diameter to 2" (as it is for CHR-70 in microTower) and reduce length to 1-5/8", then the box tuning is 53Hz (right between the EL70's 56Hz and the CHR-70's 50Hz) and the gain graph looks much more "normal".
Maybe there are aspects of T/S parameters and MLTL alignments that I just don't understand - in fact, surely there are. But normally a MLTL allows for a box tuning frequency considerably lower than Fs (as is the case for both the EL70 and CHR-70 in microTower).
Dr. Lindgren, when you have time could you confirm whether the port should be 2" x 1-5/8" or 3" x 1-5/8" for P7HD, and if it is 3" then a layman's explanation of why this will work would be greatly appreciated. I struggle with some of these concepts.
EDIT: Actually, I am now quite confused.
If I hold vent diameter at 3" (as it is for EL70 in microTower) and reduce length to 1-5/8", the box tuning goes way up to 70-ish Hz (right at driver Fs) and the gain graph has a huge hump.
If I change the port diameter to 2" (as it is for CHR-70 in microTower) and reduce length to 1-5/8", then the box tuning is 53Hz (right between the EL70's 56Hz and the CHR-70's 50Hz) and the gain graph looks much more "normal".
Maybe there are aspects of T/S parameters and MLTL alignments that I just don't understand - in fact, surely there are. But normally a MLTL allows for a box tuning frequency considerably lower than Fs (as is the case for both the EL70 and CHR-70 in microTower).
Dr. Lindgren, when you have time could you confirm whether the port should be 2" x 1-5/8" or 3" x 1-5/8" for P7HD, and if it is 3" then a layman's explanation of why this will work would be greatly appreciated. I struggle with some of these concepts.
Last edited:
The only data I have for the microtowers indicates:
microTower (twin driver): CHR and EL both used a single 2in diameter x 2 1/4in long vents
chubbyTower CHR (quad driver): twin 2in diameter x 2 1/4in long vents, or a single 2.83in diameter x 2 1/4in long vent
chubbyTower EL (quad driver): twin 3in diameter x 4in long vents, or a single 4.24in diameter x 4in long vent
halfTower CHR (single driver): single 2in diameter x 2 1/4in vent
halfTower EL (single driver): twin 2.12in diameter x 4in long vent
So it looks like I've wasted my time. I'll try to look at it again but I'm struggling badly to keep up with everything so please be patient.
microTower (twin driver): CHR and EL both used a single 2in diameter x 2 1/4in long vents
chubbyTower CHR (quad driver): twin 2in diameter x 2 1/4in long vents, or a single 2.83in diameter x 2 1/4in long vent
chubbyTower EL (quad driver): twin 3in diameter x 4in long vents, or a single 4.24in diameter x 4in long vent
halfTower CHR (single driver): single 2in diameter x 2 1/4in vent
halfTower EL (single driver): twin 2.12in diameter x 4in long vent
So it looks like I've wasted my time. I'll try to look at it again but I'm struggling badly to keep up with everything so please be patient.
Assuming a 3in diameter vent (which I do not have a record of)
microTower = 4in duct length (untapered)
halfTower = 6in (not too happy about that length although the down-venting should hopefully attenuate any unwanted 1/2 wave modes)
edit: I've dug through some old pdfs on a spare HDD and stand corrected; I've found one noting a 3in diameter duct for the EL. Unfortunately I sometimes struggle to keep up with everything. So no change required for the 7HD. Just watch the impedance if the drivers are in parallel -I generally have 3ohms as my minimum threshold.
microTower = 4in duct length (untapered)
halfTower = 6in (not too happy about that length although the down-venting should hopefully attenuate any unwanted 1/2 wave modes)
edit: I've dug through some old pdfs on a spare HDD and stand corrected; I've found one noting a 3in diameter duct for the EL. Unfortunately I sometimes struggle to keep up with everything. So no change required for the 7HD. Just watch the impedance if the drivers are in parallel -I generally have 3ohms as my minimum threshold.
Last edited:
I am so sorry if I have wasted your time. Perhaps I should have been clearer.
Attached is the only information that I have on microTower tuning (for the dual driver versions of CHR-70 and EL70).
As you can see, it shows the single 2" x 2-1/4" vent for the dual CHR-70 (main diagram) and the zoom view shows a single 3" x 4" vent for the dual EL70 configuration.
I used a 3" x 4" vent for my dual EL70 boxes, based on that information. (This corresponds perfectly with your ports for the chubbyTower EL (quad). Double the drivers, double the ports.
I am not sure that you have wasted your time, actually. It seems to me that the 2" x 1-5/8" port is correct for the P7HD.
Attached is the only information that I have on microTower tuning (for the dual driver versions of CHR-70 and EL70).
As you can see, it shows the single 2" x 2-1/4" vent for the dual CHR-70 (main diagram) and the zoom view shows a single 3" x 4" vent for the dual EL70 configuration.
I used a 3" x 4" vent for my dual EL70 boxes, based on that information. (This corresponds perfectly with your ports for the chubbyTower EL (quad). Double the drivers, double the ports.
I am not sure that you have wasted your time, actually. It seems to me that the 2" x 1-5/8" port is correct for the P7HD.
Attachments
Note: I was typing that while you were replying, Scott.
So, stick with 3" x 4" or go with 2" x 1-5/8"? There is a slight difference in tuning (~3Hz).
My boxes are pretty heavily damped.
EDIT: the obvious answer is to stick with 3" x 4" and see how it goes, and only mess with it if I feel it is necessary - which I doubt.
Thanks for the warning on impedance. That's been a primary challenge for me with this retrofit because I only have 4, 8 and 16 ohm taps available on my SET. I am tempted to wire them in series for 12 ohms nominal and then I can try them on both the 8 and 16ohm taps and decide what sounds best.
I dunno... still mulling it over.
So, stick with 3" x 4" or go with 2" x 1-5/8"? There is a slight difference in tuning (~3Hz).
My boxes are pretty heavily damped.
EDIT: the obvious answer is to stick with 3" x 4" and see how it goes, and only mess with it if I feel it is necessary - which I doubt.
Thanks for the warning on impedance. That's been a primary challenge for me with this retrofit because I only have 4, 8 and 16 ohm taps available on my SET. I am tempted to wire them in series for 12 ohms nominal and then I can try them on both the 8 and 16ohm taps and decide what sounds best.
I dunno... still mulling it over.
Last edited:
You are trying to sim an ML-TL w a BR modeler. You will only get vague answers.
These drivers can move some air, ue the bigger vent.
dave
)
The rolled off top end was the only attribute that stopped me from buying a pair of EL70s.
jeff
It didn't prevent me from enjoying my microTowers for quite a few years and thousands of hours of listening. They just had a very laid back, classic "easy listening" feel to them. I compensated for a while with some DSP and chose amps, DACs etc. that were on the "brighter", more "analytical" side in order to squeeze as much detail out of the EL70 as I could.
The Pluvia 7.2HD is in another league. It's that simple. It is no exaggeration to say I am hearing things in songs that I don't remember hearing before. The highs aren't only way more substantial, they are much more coherent and realistic. Cymbals, the "air" in vocals and through wind instruments, fingers on strings - superb.
The Pluvia 7.2HD is in another league. It's that simple. It is no exaggeration to say I am hearing things in songs that I don't remember hearing before. The highs aren't only way more substantial, they are much more coherent and realistic. Cymbals, the "air" in vocals and through wind instruments, fingers on strings - superb.
Less important, but worth noting - I love the way they look in my microTowers.
These are the "soft chrome" (as opposed to the "vintage gold") and I am surprised and pleased that they have a warmer colour tone than pictured on Madisound or markaudio.com.
Dave, before you correct me on the colour names once again, I will note that I am using the exact names used on markaudio.com. If they have these colour names wrong, perhaps you should send them a heads-up.
These are the "soft chrome" (as opposed to the "vintage gold") and I am surprised and pleased that they have a warmer colour tone than pictured on Madisound or markaudio.com.
Dave, before you correct me on the colour names once again, I will note that I am using the exact names used on markaudio.com. If they have these colour names wrong, perhaps you should send them a heads-up.
Attachments
Member
Joined 2009
Paid Member
If it's of any value, I did a single driver micro-tower around the EL-70 which can be cut from a single panel from Home Depot.
MARTELLO-2, a mini-tower from a single 2' x 4'
I would add that I find these speakers to be elegant but also tippy and so they're not suited for use where they maybe easily disturbed or knocked over because they are tall and skinny. Some kind of simple outrigger/stabilizer would be a great addition but I've not had time to add one.
Bass performance is astonishing for this small driver, I wonder if the Pluvia is up to the same ?
MARTELLO-2, a mini-tower from a single 2' x 4'
I would add that I find these speakers to be elegant but also tippy and so they're not suited for use where they maybe easily disturbed or knocked over because they are tall and skinny. Some kind of simple outrigger/stabilizer would be a great addition but I've not had time to add one.
Bass performance is astonishing for this small driver, I wonder if the Pluvia is up to the same ?
Attachments
Cool design, Bigun!
I've only barely got the cones moving on my P7.2HD, but my immediate response is YES! I do not feel like there is anything missing at all in the low end - and perhaps these are even slightly more refined. I seem to get slightly more bass at lower volumes than with the EL70s.
Really, really impressive.
I've only barely got the cones moving on my P7.2HD, but my immediate response is YES! I do not feel like there is anything missing at all in the low end - and perhaps these are even slightly more refined. I seem to get slightly more bass at lower volumes than with the EL70s.
Really, really impressive.
Last edited: