Tower with Sierra 2 woofers?

[Sivar]

I notice the Sierra Tower's woofers use nearly the same driver (with longer windings, according to one review) as the Sierra 1.

Since I am so impressed with the Sierra 2's larger woofer, I wonder why was it rejected for use in the tower (perhaps with similar modifications)?

I am not questioning the decision and won't pretend to know a thing about speaker design -- I am just curious.

[curtis]

I notice the Sierra Tower's woofers use nearly the same driver (with longer windings, according to one review) as the Sierra 1.

Since I am so impressed with the Sierra 2's larger woofer, I wonder why was it rejected for use in the tower (perhaps with similar modifications)?

I am not questioning the decision and won't pretend to know a thing about speaker design -- I am just curious.
With all three speakers, the design objectives for the woofer are different. In other words, what the woofers were expected to do, are very different.

[GirgleMirt]

I wonder why was it rejected for use in the tower (perhaps with similar modifications)?

I don't think it was rejected, I think it just didn't exist. Historically, I think it went like this:

Sierra1
Sierra towers
Sierra1 NrT
Sierra RAAL towers
Sierra2

So when the towers were designed, there was no Sierra2 & so no sierra 2 drivers. As you mentioned, tower woofers are similar to the Sierra1, and later on the Sierra1 NrT upgrade was made available, using the same tweeter as the towers. So the Sierra2 drivers most probably did not exist and could not be chosen for the towers!

[davef]

I notice the Sierra Tower's woofers use nearly the same driver (with longer windings, according to one review) as the Sierra 1.

Since I am so impressed with the Sierra 2's larger woofer, I wonder why was it rejected for use in the tower (perhaps with similar modifications)?

I am not questioning the decision and won't pretend to know a thing about speaker design -- I am just curious.

The Sierra-2 woofer was specifically designed for great tight bass -and- clean detailed mids up to about 5kHz. For its intended purpose, it is about as good as one can get.

In general, the wider the frequency response needed from a woofer -- the greater the compromise. For example, I have found that it is basically impossible to have a woofer play accurately down to 35Hz while also having accurate mids up to about 4kHz. The reason for this is simple, to play deep bass requires a significant amount of mass that must move back and forth (longer voice coil, more windings, heavier mass cone etc.) These are the polar opposite of the characteristics one would want for accurately reproducing upper mids with an accurate transient response, which require low mass and a light and stiff cone.

The Sierra-2 woofer is quite special -- it is fully optimized for the bandwidth required of it and is about as near a perfect woofer as one can get for its intended purpose.

if we were to replace the bass woofers in the Sierra Tower with the Sierra-2 woofers, we would lose a significant amount of bass extension. The exceptional midrange response of the S2 woofer would also serve no purpose in the tower, which uses a dedicated very low mass high efficiency midrange. Overall performance of the towers would be slightly compromised yet we would be adding a significant amount of additional expenses as the S2 woofers are very expensive.

This is one of Ascend's key design features, we never use any driver (woofer or tweeter) in an inappropriate application. Every driver is fully optimized (often being fully custom designed) for the intended application...

Hope this makes sense!

[kdaq]

Makes sense. How do subwoofer designers balance this, though? You can't get deep bass with low mass, yet you can't get good control with high mass. Rythmik even makes a point of saying that their servo sensor is decoupled from the driver so it doesn't add moving mass.

Could you make a sub with light material but a bigger cone to compensate?

[Sivar]

Hope this makes!

Thank you for the detailed and interesting explanation...straight from the source.
Sadly, I fell to the "halo effect" cognitive bias because...well, the Sierra 2 woofers look like they really mean business.

And they do. I can't wait to hear the towers. The Sierra 2's are the first home audio speakers that haven't disappointed me since I was 15.

[ne24611]

The Sierra-2 woofer was specifically designed for great tight bass -and- clean detailed mids up to about 5kHz. For its intended purpose, it is about as good as one can get.

In general, the wider the frequency response needed from a woofer -- the greater the compromise. For example, I have found that it is basically impossible to have a woofer play accurately down to 35Hz while also having accurate mids up to about 4kHz. The reason for this is simple, to play deep bass requires a significant amount of mass that must move back and forth (longer voice coil, more windings, heavier mass cone etc.) These are the polar opposite of the characteristics one would want for accurately reproducing upper mids with an accurate transient response, which require low mass and a light and stiff cone.

The Sierra-2 woofer is quite special -- it is fully optimized for the bandwidth required of it and is about as near a perfect woofer as one can get for its intended purpose.

if we were to replace the bass woofers in the Sierra Tower with the Sierra-2 woofers, we would lose a significant amount of bass extension. The exceptional midrange response of the S2 woofer would also serve no purpose in the tower, which uses a dedicated very low mass high efficiency midrange. Overall performance of the towers would be slightly compromised yet we would be adding a significant amount of additional expenses as the S2 woofers are very expensive.

This is one of Ascend's key design features, we never use any driver (woofer or tweeter) in an inappropriate application. Every driver is fully optimized (often being fully custom designed) for the intended application...

Hope this makes!

Dave -- The related question that comes to mind is; could a woofer for the towers be developed that that has the same radiating area as the S-2 woofer? More specifically, could a 6" woofer be developed for the towers that would provide improved lower end response, but still fit the same cut-out in the cabinet? This new woofer would not be the S-2 woofer, but it may share some of the design aspects of the S-2 woofer. Not sure if the performance increase would justify the development and productions costs, but then only Dave can answer that question.

Just curious!

[davef]

Makes sense. How do subwoofer designers balance this, though? You can't get deep bass with low mass, yet you can't get good control with high mass. Rythmik even makes a point of saying that their servo sensor is decoupled from the driver so it doesn't add moving mass.

Could you make a sub with light material but a bigger cone to compensate?

Subwoofer drivers typically start to naturally roll off at 200Hz and higher. There is no regard to midrange response from a subwoofer. Lighter mass subwoofer cones will typically require more radiating area (larger cone) to have deep extension which would then also require larger cabinet volume. Or, low frequency extension can be gained by using more active equalization in the amplifier, which would require a higher power amplifier. It is all about choosing the compromises -- gain some performance here, compromise elsewhere etc.

[kdaq]

Interesting. Speaker design obviously has quite a bit of science to it, but it feels like the balance / compromise side is art. :)

[davef]

Dave -- The related question that comes to mind is; could a woofer for the towers be developed that that has the same radiating area as the S-2 woofer? More specifically, could a 6" woofer be developed for the towers that would provide improved lower end response, but still fit the same cut-out in the cabinet? This new woofer would not be the S-2 woofer, but it may share some of the design aspects of the S-2 woofer. Not sure if the performance increase would justify the development and productions costs, but then only Dave can answer that question.

Just curious!

If you mean deeper bass response in the towers when you mention "improved low end response", there are only 2 possibilities:

If a new woofer was designed with a larger radiating area (like the S2 woofer), to get deeper bass the cabinet volume would have to increase by about 1/2 of a cubic foot. This is significant and would also change the overall performance of the speaker (which would have to be compensated for) as well as increase the cabinet costs.

The other option would be to use the same radiating area, but increase moving mass, which would require compliance changes as well as magnet strength changes. The associated costs of this would be minor and the cabinet would not require changes, however, we would then lose a significant amount of efficiency. The speaker's sensitivity would drop down to about 85-86dB and as such, the entire crossover network would need to be changed and padding circuits would have to be placed in both the tweeter network and midrange network. We would end up with deeper bass response, but with much lower efficiency, and a more complex crossover network.

One of the neat things about the Sierra Towers is that efficiency of the drivers was specifically designed so that they ideally match without the need for padding circuits.

As I previously mentioned, it is all about compromise -- it is a complex game of give and take. With that said, don't let the published low end specifications of our towers concern you, they are honest and the bass is quite nice -- it is punchy, deep and detailed.

[RicardoJoa]

I got an idea.
If someone wanted to have more extension, why not desinged an active pair of subs sytem that can be perfectly integrated to the fronts without the need of external processors? Sort of like connecting the cable from the towers to the pairs of active sub.
I know that this could be done with some subs that offer speaker wires connections, but the integration is far from ideal.
So the concept is that the subs need to be placed at certain parameters / distance to be in phase with the towes, or even the sierra bookshelves.