So here is the crossover in the flesh.
And a test rig I set up.
That 8" sub is not the driver I intend to use (I haven't ordered the 6.5" drivers yet) but it is the same impedance so I thought that I would see how it goes. This driver, though capable of much more total output than the ones I am ordering, is not nearly as efficient so the balance is not ideal, however, even at that the difference is tremendous. Even as high up in the frequency range as the tympani it is a night and day improvement over the other channel where I am using the FR in ported box. The low bass note on Boston's "The Journey" is very clear where it was only the harmonics that one heard in the ported FR alone.
The combination of the sealed box for the FR and the 1st order HP allowed me to throw a lot more bass at the system without overextending the driver. It also seemed that the helper woofer and crossover allowed the FR to really sing with increased clarity. Can't wait to get the new drivers and start putting it all together.
And a test rig I set up.
That 8" sub is not the driver I intend to use (I haven't ordered the 6.5" drivers yet) but it is the same impedance so I thought that I would see how it goes. This driver, though capable of much more total output than the ones I am ordering, is not nearly as efficient so the balance is not ideal, however, even at that the difference is tremendous. Even as high up in the frequency range as the tympani it is a night and day improvement over the other channel where I am using the FR in ported box. The low bass note on Boston's "The Journey" is very clear where it was only the harmonics that one heard in the ported FR alone.
The combination of the sealed box for the FR and the 1st order HP allowed me to throw a lot more bass at the system without overextending the driver. It also seemed that the helper woofer and crossover allowed the FR to really sing with increased clarity. Can't wait to get the new drivers and start putting it all together.
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Hi M,
Looks like your project is shaping up very nicely.
Some thoughts for you on selecting a 6.5" driver (if you've not yet fully decided).
1 - Check out moving masses. You'll usually get more resonant output from lower mass cones and power-trains
2 - Take a look at the depth of the cone. The wider shallow profile coned drivers usually offer better dispersion and closer match the CHR-70 in this respect.
3 - Take a good look at the front suspension. Large forward projecting (forward-hung) suspensions may present dispersion problems. The cheaper drivers mostly use lower grade materials so the suspension is larger to retain tolerable linear excursion. More shallow, wide front suspensions usually means the designer has put some effort into the driver. Chances are more money has been spent on the driver's power-train components and dispersion has been factored into its design. Its more challenging to find drivers with back projecting (reverse-hung) suspensions as these are more of a design challenge. They usually require the more expensive 3 or 4 mix Ei graded materials. Fewer driver designers have sufficient knowledge on the mechanical properties of this type of suspension so tend to steer clear.
4 - Be prepared to further experiment with the 6.5 box to driver optimisation (if possible). Sims are a good guide but won't always give you the final listening solution.
Cheers
Mark.
Looks like your project is shaping up very nicely.
Some thoughts for you on selecting a 6.5" driver (if you've not yet fully decided).
1 - Check out moving masses. You'll usually get more resonant output from lower mass cones and power-trains
2 - Take a look at the depth of the cone. The wider shallow profile coned drivers usually offer better dispersion and closer match the CHR-70 in this respect.
3 - Take a good look at the front suspension. Large forward projecting (forward-hung) suspensions may present dispersion problems. The cheaper drivers mostly use lower grade materials so the suspension is larger to retain tolerable linear excursion. More shallow, wide front suspensions usually means the designer has put some effort into the driver. Chances are more money has been spent on the driver's power-train components and dispersion has been factored into its design. Its more challenging to find drivers with back projecting (reverse-hung) suspensions as these are more of a design challenge. They usually require the more expensive 3 or 4 mix Ei graded materials. Fewer driver designers have sufficient knowledge on the mechanical properties of this type of suspension so tend to steer clear.
4 - Be prepared to further experiment with the 6.5 box to driver optimisation (if possible). Sims are a good guide but won't always give you the final listening solution.
Cheers
Mark.
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I'll be honest here. With the amount of money I have already spent on this project and the amount waiting in the wings I am afraid I will have to economize on the woofer. I justify this by telling myself that it only has to give support from 40Hz to 100Hz (plus the overlap) so good behavior in the mid range is not necessary. So this is what I was planning to use.
6-1/2" Woofer 4 Ohm
I know, probably a cheapo driver and xmax is only 3mm but the larger cone area (v.s. the CHR-70) and the likelyhood that xmech is probably a little larger than that makes me believe that they might be just fine. At $10 a piece I figure it is worth a try and if they aren't up to the task I can still use them in some other non-critical application.
I was a bit more choosy when picking the full range to use of course.
6-1/2" Woofer 4 Ohm
I know, probably a cheapo driver and xmax is only 3mm but the larger cone area (v.s. the CHR-70) and the likelyhood that xmech is probably a little larger than that makes me believe that they might be just fine. At $10 a piece I figure it is worth a try and if they aren't up to the task I can still use them in some other non-critical application.
I was a bit more choosy when picking the full range to use of course.
I'll be honest here. With the amount of money I have already spent on this project and the amount waiting in the wings I am afraid I will have to economize on the woofer.
I know, probably a cheapo driver and xmax is only 3mm but the larger cone area (v.s. the CHR-70) and the likelyhood that xmech is probably a little larger than that makes me believe that they might be just fine. At $10 a piece I figure it is worth a try and if they aren't up to the task I can still use them in some other non-critical application.
I was a bit more choosy when picking the full range to use of course.
Hi M,
This woof might work for your project but best not to expect too much from it. It is "bargain basement", foam front suspension will likely be a limiting factor so its 3-mm quoted excursion is about all you'll get. Its Mech X should be around 9-mm (I know the factory that makes this driver) but it will distort well before its gets close to this max. Moving mass isn't quoted but from my memory, its in the 14 to 16g range so if driven gently, it may sort of sound OK given you only need it for a low end boost.
Cheers
Mark.
Thanks Mark. I had considered this driver...
Aurasound NS6-255-4A 6" Paper Cone Woofer 4 ohm: Madisound Speaker Store
But its 80% higher VAS made the TLs I modeled much larger than the PE driver. I could try ported I suppose. I may rerun the models and see if there is any way to make it work if you think it would be a much better choice. I know the xmax is greater (I think I saw 4 or 5mm quoted somewhere).
This one...
Aurasound NS8-385-4A 8" Woofer: Madisound Speaker Store
might be even better and even though it is a larger driver the VAS is actually a little less than the 6.5" Aura. It is twice the price but it is still in the quite reasonable category. In fact I had originally settled on this one but thought of going with the PE because both price and cabinet size were still less. Maybe I should stick to my first instinct. What do you think?
Aurasound NS6-255-4A 6" Paper Cone Woofer 4 ohm: Madisound Speaker Store
But its 80% higher VAS made the TLs I modeled much larger than the PE driver. I could try ported I suppose. I may rerun the models and see if there is any way to make it work if you think it would be a much better choice. I know the xmax is greater (I think I saw 4 or 5mm quoted somewhere).
This one...
Aurasound NS8-385-4A 8" Woofer: Madisound Speaker Store
might be even better and even though it is a larger driver the VAS is actually a little less than the 6.5" Aura. It is twice the price but it is still in the quite reasonable category. In fact I had originally settled on this one but thought of going with the PE because both price and cabinet size were still less. Maybe I should stick to my first instinct. What do you think?
Hi M,
Let me have a look in my storage and sample rooms, see if I've got a pair of woof drivers that may help you out. Email me on: support@markaudio.com
Cheers
Mark.
Well, I am trying to push the budget a little bit (maybe I can sell that gas radiant heater I never installed ) Right now I am looking at possibly the Dayton Reference 6" 4 ohm or the Silver Flute 6.5" 4 ohm. Simulations indicate that either one could work within the size limitation that I have as either a TL or Ported and give maximum output of a bit over 100dB per channel down to 40Hz. I suspect that the Dayton might be a little bit cleaner but I would love to hear from others with experience with these drivers.
I have looked at some 7" and 8" drivers but most made it difficult to get down under 25 Liters for the enclosure. The MCM 8" long throw sub was an exception here but my concern is that it would be lacking in detail compared to the other options.
It has been suggested that I move the crossover up closer to 150Hz which makes some sense to me as it would reduce the excursion on the FR and thus reduce distortion including Doppler effect and further protect the driver from exceeding xmax. My only concern is that we are getting up pretty high in the fundamentals of male vocal range but crossover would still be out of the harmonics.
I played around with LT spice to see what I could do. I have on hand a couple of chokes which I believe to be about 3.5 to 4mH. If I switch the caps in the tweeter and woofer circuits so that the woofer has 400uf and the tweeter has 250uf and then add the new choke between the existing LP network and the woofer so that there is a "T" network of 9mH-400uf-4mH, the I get a crossover of around 140Hz to 160Hz and a third order roll off on the LP. The third order slope would be especially useful if I go with a TL as it would help knock out any remaining resonances.
Would love to hear your thoughts.
) Right now I am looking at possibly the Dayton Reference 6" 4 ohm or the Silver Flute 6.5" 4 ohm. Simulations indicate that either one could work within the size limitation that I have as either a TL or Ported and give maximum output of a bit over 100dB per channel down to 40Hz. I suspect that the Dayton might be a little bit cleaner but I would love to hear from others with experience with these drivers.I have looked at some 7" and 8" drivers but most made it difficult to get down under 25 Liters for the enclosure. The MCM 8" long throw sub was an exception here but my concern is that it would be lacking in detail compared to the other options.
It has been suggested that I move the crossover up closer to 150Hz which makes some sense to me as it would reduce the excursion on the FR and thus reduce distortion including Doppler effect and further protect the driver from exceeding xmax. My only concern is that we are getting up pretty high in the fundamentals of male vocal range but crossover would still be out of the harmonics.
I played around with LT spice to see what I could do. I have on hand a couple of chokes which I believe to be about 3.5 to 4mH. If I switch the caps in the tweeter and woofer circuits so that the woofer has 400uf and the tweeter has 250uf and then add the new choke between the existing LP network and the woofer so that there is a "T" network of 9mH-400uf-4mH, the I get a crossover of around 140Hz to 160Hz and a third order roll off on the LP. The third order slope would be especially useful if I go with a TL as it would help knock out any remaining resonances.
Would love to hear your thoughts.
Hi I am new on here and I hope I'm not breaking any rules. I saw that you mentioned the aurasound ns6-255-4a drivers in one of your posts. Is there any chance that you have these drivers and if so would you consider selling them?
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Sorry, This project died on the vine for reasons completely apart from the drivers mentioned. I got the power amp built but never got to the rest and the need for it is now gone.