Introducing the Sierra-LX!!!

[davef]

Two questions.

1) Are the port plugs needed if someone is using room correction/EQ to tame down any excess bass energy due to placement?

2) Will the plugs be included with upgrade kits as well?

Good questions:

1) Are the port plugs needed if someone is using room correction/EQ to tame down any excess bass energy due to placement?

Room-Eq can do things that the plugs cannot, and the plugs can do things EQ cannot. Best solution is using both. Ideally, turn off all auto-eq - determine which plug is most beneficial, and then run auto-eq.

2) Will the plugs be included with upgrade kits as well?

No, Q-Plugs will need to be purchased separately if a customer wishes to use them. That, or we would need to raise the prices on the kits.

Take care!

[SunByrne]

Unfortunately, due to the sheer force the LX woofer can produce, those original Q-Plugs did not perform well in the LX.

I now have this wonderful mental image of Dave standing there, clipboard in hand, turning up the volume and watching Q-plugs flying out of the back of a pair of LXs. It just made me laugh—so thanks for that, Dave.

Also, as I may perhaps be one of the people you were referring to with the whole "lengthy in-depth and often highly technical discussions with our customers" it has occurred to me that the port tune frequency for the cabinets was really designed to match the original S1 woofer, which doesn't go nearly as deep as the LX woofer. So it seems like it might be desirable to lower the port tune frequency, but of course you're kind of stuck with the original cabinet design. (Which, I, Mr. I-can-now-upgrade-a-Sierra-blindfolded, still greatly appreciate.) But if you could have tweaked the port a little for the LXs, you would have, yes?

Side note: I really do have to try to get out to Ascend again sometime so I can actually meet you in person—and bug you with these kinds of questions not on the forum or over email.

[davef]

I now have this wonderful mental image of Dave standing there, clipboard in hand, turning up the volume and watching Q-plugs flying out of the back of a pair of LXs. It just made me laugh—so thanks for that, Dave.

Haha - aside from clipboard in-hand, this is EXACTLY what happened. You just made me laugh as it was a funny memory. This is why we went with higher density foam, which also better damps any port noise.

it has occurred to me that the port tune frequency for the cabinets was really designed to match the original S1 woofer, which doesn't go nearly as deep as the LX woofer. So it seems like it might be desirable to lower the port tune frequency, but of course you're kind of stuck with the original cabinet design. (Which, I, Mr. I-can-now-upgrade-a-Sierra-blindfolded, still greatly appreciate.) But if you could have tweaked the port a little for the LXs, you would have, yes?

While the original tuning of the cabinet and port (that is a custom tooled port tube) was originally for the Sierra-1, the LX woofer was designed specifically for this cabinet volume and port tuning. It was actually one of the last engineering projects Claus Futtrup at SEAS completed before he moved to a different country.

The bass response of the LX is very smooth, flat and accurate - the issue is that in many small rooms, SBIR and room modes can become an issue as ideal placement for a bookshelf speaker is never going to be the ideal placement for accurate bass. Few, if any bookshelf speakers, are capable of digging this deep with such authority.

We did the same thing with Sierra-1 if you remember, Q-Plugs to help aid in room modes, placement issues etc.

Side note: I really do have to try to get out to Ascend again sometime so I can actually meet you in person—and bug you with these kinds of questions not on the forum or over email.

You are welcome any time!

[High Fidelity]

The bass response of the LX is very smooth, flat and accurate - the issue is that in many small rooms, SBIR and room modes can become an issue as ideal placement for a bookshelf speaker is never going to be the ideal placement for accurate bass. Few, if any bookshelf speakers, are capable of digging this deep with such authority.

Would effectively integrating two subwoofers to deal with room modes and even out the bass response in a small room negate the need for Q-Plugs?

[davef]

Would effectively integrating two subwoofers to deal with room modes and even out the bass response in a small room negate the need for Q-Plugs?

Yes, provided that you are using bass management properly.

I should clarify - Q-Plugs are really for those who are using our Sierra LX full range with less than optimal placement and/or annoying room modes. They can also aid in integrating the speakers and sub and for many customers, they can just be another way to "tweak" things to achieve perfection.

[SunByrne]

While the original tuning of the cabinet and port (that is a custom tooled port tube) was originally for the Sierra-1, the LX woofer was designed specifically for this cabinet volume and port tuning. It was actually one of the last engineering projects Claus Futtrup at SEAS completed before he moved to a different country.

This is kind of more where I was going with the question. It seems like a design challenge to have the same port tuning for the S1 woofer and the LX woofer since the LX woofer digs so much deeper. I was thinking it would have been easier for you to design the LX if you had been able to change the port tuning. I did not in any way mean to suggest that you hadn't solved it, but rather it that solving it would have been more straightforward if tweaking the cabinet had been on the table as an option.

The bass response of the LX is very smooth, flat and accurate

I know, and greatly appreciate it! I got rid of the sub in my study when I switched from EX to LX—didn't need it anymore.

We did the same thing with Sierra-1 if you remember, Q-Plugs to help aid in room modes, placement issues etc.

Yes, I know. In fact, I have a set of Q-Plugs (the "O" type) in the pair of S1s that are in my campus office. I even still have the original box they came in, which is where I keep the "S" set and the white cotton gloves that came with my first S1s. I still use those gloves whenever I handle those original glossy cabinets.

[davef]

This is kind of more where I was going with the question. It seems like a design challenge to have the same port tuning for the S1 woofer and the LX woofer since the LX woofer digs so much deeper. I was thinking it would have been easier for you to design the LX if you had been able to change the port tuning. I did not in any way mean to suggest that you hadn't solved it, but rather it that solving it would have been more straightforward if tweaking the cabinet had been on the table as an option.

Actually, it is far easier for me to have SEAS optimize a woofer's T/S parameters for a specific cabinet volume and tuning, then it is for me to design a new port tube. And infinitely less costly -- if I recall, the tooling costs for that port tube were about $6K and that was about 15 years ago.

These are already tuned quite low, ~45Hz... Port tuning is quite complex, to tune lower - we would have to increase the length of the port tube or decrease the diameter. Increasing the length is problematic and would require increasing the depth of the cabinet. Decreasing the diameter leads to significant increases in turbulence, "chuffing" and port resonance.

Few manufacturers have the relationships and history with vendors like we do, or purchase in large enough quantities for them to justify custom made products. We are lucky to have this option, without it - there would have never been the EX or LX woofers.

[SunByrne]

Actually, it is far easier for me to have SEAS optimize a woofer's T/S parameters for a specific cabinet volume and tuning, then it is for me to design a new port tube. And infinitely less costly -- if I recall, the tooling costs for that port tube were about $6K and that was about 15 years ago.

Super interesting! I love that you're so willing to address my technical ignorance, so I will keep barreling ahead.

So is the LX woofer essentially designed with a dip in response around 45Hz to make up for the port tune? Somehow I feel like it can't be that simple.

[davef]

So is the LX woofer essentially designed with a dip in response around 45Hz to make up for the port tune? Somehow I feel like it can't be that simple.

I don't follow you on this. I am going to assume you mean that engineers design a dip in the frequency response of a woofer to compensate for output of the port?

If that is your assumption, that is not how woofers and ports work. The 2 work together, they are not separate components and one does not design a dip in the response of a transducer to compensate for the port output (that is not mechanically possible) With proper tuning, the port itself takes care of this.

The woofer and port work together, at port tune - the port is providing 100% of the output as the woofer cone itself will not move. You can see this by examining the impedance curve of a ported speaker , the trough between the 2 impedance peaks. In the case of Sierra LX, it is at 45Hz,

https://cdn.shopify.com/s/files/1/01...g?v=1650266886

At 45Hz, the port is providing all of the output, the woofer wont move back and forth. As you move higher in frequency above 45Hz, the output of the port lessens and is handed off to the woofer. There is a general misconception regarding ports that they relieve the air-pressure within the cabinet. This is not true, ports actually increase the air-pressure within the cabinet, thus helping limit overall woofer excursion at port tune and higher.

In a ported speaker, when a woofer moves forward, air is forced out of the port, creating a lack of pressure in the cabinet which helps the woofer back into resting position. When a woofer moves inward, air is forced back into the enclosure through the port increasing the pressure in the cabinet which helps the woofer cone move forward into resting position. Below port tune, this behavior changes and the woofer will act as if it is in free-air with no air-spring in the enclosure.

Ideally, you generally try to match the port tune frequency to the resonant frequency of the woofer (or tune the port slightly lower, or tune woofer resonant frequency slightly higher) doing so optimizes the response of the overall system because at the woofer's resonant frequency, the woofer will produce the most distortion and is least controlled.

So, when designing a woofer for a specific cabinet volume and port tune - the transducer engineer will try to get the woofer resonant frequency to match the port tune or come very close. There is quite a bit more involved (including optimizing the Thiele/Small parameters of the woofer) - but this should provide you with at least a general understanding.

A speaker port is a Helmholtz Resonator, Wikipedia has a decent explanation as to how it functions.

[davef]

I don't follow you on this. I am going to assume you mean that engineers design a dip in the frequency response of a woofer to compensate for output of the port?

If that is your assumption, that is not how woofers and ports work. The 2 work together, they are not separate components and one does not design a dip in the response of a transducer to compensate for the port output (that is not mechanically possible) With proper tuning, the port itself takes care of this.

The woofer and port work together, at port tune - the port is providing 100% of the output as the woofer cone itself will not move. You can see this by examining the impedance curve of a ported speaker , the trough between the 2 impedance peaks. In the case of Sierra LX, it is at 45Hz,

https://cdn.shopify.com/s/files/1/01...g?v=1650266886

At 45Hz, the port is providing all of the output, the woofer wont move back and forth. As you move higher in frequency above 45Hz, the output of the port lessens and is handed off to the woofer. There is a general misconception regarding ports that they relieve the air-pressure within the cabinet. This is not true, ports actually increase the air-pressure within the cabinet, thus helping limit overall woofer excursion at port tune and higher.

In a ported speaker, when a woofer moves forward, air is forced out of the port, creating a lack of pressure in the cabinet which helps the woofer back into resting position. When a woofer moves inward, air is forced back into the enclosure through the port increasing the pressure in the cabinet which helps the woofer cone move forward into resting position. Below port tune, this behavior changes and the woofer will act as if it is in free-air with no air-spring in the enclosure.

Ideally, you generally try to match the port tune frequency to the resonant frequency of the woofer (or tune the port slightly lower, or tune woofer resonant frequency slightly higher) doing so optimizes the response of the overall system because at the woofer's resonant frequency, the woofer will produce the most distortion and is least controlled.

So, when designing a woofer for a specific cabinet volume and port tune - the transducer engineer will try to get the woofer resonant frequency to match the port tune or come very close. There is quite a bit more involved (including optimizing the Thiele/Small parameters of the woofer) - but this should provide you with at least a general understanding.

A speaker port is a Helmholtz Resonator, Wikipedia has a decent explanation as to how it functions.

As a follow-up to this, here are some measurements of the Dali Spektor 1. Note, I chose this speaker for no reason other than it is ported and was one of the first that popped up when I visited ASR.

Here is the speaker impedance:

https://www.audiosciencereview.com/f...er-png.142076/

Note the trough between the 2 large impedance peaks. Looks to be at ~60Hz. That is the port tune frequency. Also note the impedance peak at 110Hz and the other peak at ~ 35Hz.

Now look at the response of the woofer and port:

https://www.audiosciencereview.com/f...er-png.142069/

You will notice how the woofer output starts to decrease as the port output increases. At ~ 110Hz, the output of the port ~matches the output of the woofer, which also corresponds to the impedance peak I mentioned at ~110Hz.

Now look at the woofer output at port tune frequency (~60Hz). It is 20dB down in level and, at this same frequency, the output of the port is at its greatest. That dip you see in the woofer response at 60Hz is caused not by the design of the woofer, but by the air-pressure in the cabinet limiting the movement of the woofer cone.

Now below that frequency, you will notice that the output of port and woofer start to mirror each other rather than oppose each other. That is because we are now below port tune frequency and the port no longer acts like a Helmholtz Resonator and the air-pressure in the cabinet becomes the same as in open air, thus the woofer (and port) become unloaded and the woofer must rely solely on its suspension system to limit excursion and move the woofer back into resting position. This is valuable info because these low frequencies at moderate volume can damage the woofer. (frequencies lower than the lowest impedance peak shown in the impedance measurement)

You will notice with our LX:

https://cdn.shopify.com/s/files/1/01...g?v=1650266886

The port tune is at 45Hz and part of the unique design of our LX woofer was for it to be able to handle frequencies even lower than port tune. You will note the first impedance peak is at ~ 23 Hz, this frequency and lower the woofer looses its control. Rather remarkable for a woofer this size...

All of these characteristics rely on a combination of the cabinet volume, port tune, internal damping and a host of woofer parameters.

Hope you find this insightful