Hi all,
After reading through the forum, I’m a bit confused while trying to design my next full-range speaker.
I’m planning to build a speaker with the SEAS FEA18RCZ 6.5" driver. The speaker box will be vented with a port, and I’m aiming to tune it to 40Hz.
Looking at the T/S parameters, I noticed that the VAS is 31L. After reviewing SEAS' application notes, I saw that their recommended VB is around half of the VAS.
This is where my confusion began. The more I read about the relationship between VB and VAS, the more confused I get.
The suggested application by SEAS doesn’t fit my design goals, and I’d like to understand what the effects would be if I created a box of, for example, 27L, 35L, or 40L (of course port length and size will change in relation to box size).
Additionally, given the physical size of the driver, I seem to be leaning toward a shallow box. Are there any rules of thumb I should consider, such as ensuring the depth is at least twice the depth of the driver, or other factors that might affect the sound? I understand that having the back of the box too close to the driver can affect its performance.
Thank you,
Avi.
After reading through the forum, I’m a bit confused while trying to design my next full-range speaker.
I’m planning to build a speaker with the SEAS FEA18RCZ 6.5" driver. The speaker box will be vented with a port, and I’m aiming to tune it to 40Hz.
Looking at the T/S parameters, I noticed that the VAS is 31L. After reviewing SEAS' application notes, I saw that their recommended VB is around half of the VAS.
This is where my confusion began. The more I read about the relationship between VB and VAS, the more confused I get.
The suggested application by SEAS doesn’t fit my design goals, and I’d like to understand what the effects would be if I created a box of, for example, 27L, 35L, or 40L (of course port length and size will change in relation to box size).
Additionally, given the physical size of the driver, I seem to be leaning toward a shallow box. Are there any rules of thumb I should consider, such as ensuring the depth is at least twice the depth of the driver, or other factors that might affect the sound? I understand that having the back of the box too close to the driver can affect its performance.
Thank you,
Avi.
Madisound is a US reseller they have several recommended options. The larger you make the box, the lower the box will go. Look here:
https://www.madisoundspeakerstore.com/approx-6-fullrange/seas-h1794-fea18rcz-7-full-range/
If you simulate all of these options, you can see the tradeoffs in power handling, maximum SPL, etc. As far as depth of box,, as long as you have damping material behind the driver it shouldn't matter much. You don't want the damping material touching the driver, though. If it moves at all with the cone it can add mass or change the parameters.
https://www.madisoundspeakerstore.com/approx-6-fullrange/seas-h1794-fea18rcz-7-full-range/
If you simulate all of these options, you can see the tradeoffs in power handling, maximum SPL, etc. As far as depth of box,, as long as you have damping material behind the driver it shouldn't matter much. You don't want the damping material touching the driver, though. If it moves at all with the cone it can add mass or change the parameters.
Baby brother to the FA22 which i have and like (needs some works).
Box size is a relationship between Vas, Fs, and Qts.
40 Hz tuning looks like about a 25 litre box to get a nice curve. But anywhere between 15-30 nlitres looks to work.
AFAIC FA22 requires an added phase plug, that will help with some of the rough bits from the whizzer, treatment with modPodge and some ZIG 2-way glue onthe baack of the whizzer edge. nLooks like the same BVC as FA22so this phase plug should fit (it, like the FA22, will probably need notches in the base). Those will help with the rough top, they should also be listened to a bit ooff axis.
My FA22 (playing downstairs)
dave
Last edited:
Thank you Ron, Madisound recommendations its a good starting point.
Dave. thank you for the deep insight. Can you please elaborate what do you mean about the phase plug? when you write notch you mean the suggested crossover by SEAS to handle the high frequencies?
Thanks
Notch filters i stay away from. The tweaks are to try to deal with the issues with the driver at the source.
By noch, i mean that he top of the pole piecce that the phase plug sits on is not flat, so you have to add physical noches o the phase plug so that it sits flat,
http://www.planet10-hifi.com/pp-install.html
Here a pictori\al installation of FE167 which is similar size to SEAS. http://p10hifi.net/tlinespeakers/FAL/167-surgery/167-surgery.html
dave
By noch, i mean that he top of the pole piecce that the phase plug sits on is not flat, so you have to add physical noches o the phase plug so that it sits flat,
http://www.planet10-hifi.com/pp-install.html
Here a pictori\al installation of FE167 which is similar size to SEAS. http://p10hifi.net/tlinespeakers/FAL/167-surgery/167-surgery.html
dave
There is nothing wrong with using the LR shelving filter suggested by SEAS for this driver for taming the rising response of this driver. Use a good quality inductor, something like: https://www.parts-express.com/Dayto...AWG-Perfect-Layer-Inductor-257-322?quantity=1
Personally, I wouldn't cut into a $250 dollar driver and Dave's modpodge and driver painting and modification tactics are not for everyone, but to each their own.
Personally, I wouldn't cut into a $250 dollar driver and Dave's modpodge and driver painting and modification tactics are not for everyone, but to each their own.
I’d rather first work on fixing a driver’s problems where they happen, as opposed to a bandaid filter. But it is reversable, tweaking a driver is not.
dave
dave