• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Speakers and Subs - FR or XO?

aschen

Member
Joined
Feb 3, 2021
Messages
92
Likes
86
I have very large mains (dynaudio c4s) and just a single sub for now (parts express DIY 18" ultimax). I thought I was a prime candidate for FR mains. However after a bunch of experimentation and in room measurements I found High passing them give better subjective and objective sound. I did land at a relatively low freq of 50hz though.

When I tried to align the sub with the speakers playing full range, they would always ad in some spots and subtract in others. These interactions were pretty substantial in amplitude as well. In the end I was able to make things much smoother in the listening position with the speakers high passed. The added available dynamic range of relieving the mains of spectrum less than 50Hz is a big plus as well, even with 120 lbs per mains.

For smaller less LF capable mains I would definately be high passing the mains. I had some snobophile objections to using a minidspHD for this purpose originally because I wanted to avoid the extra ADC and DAC operations for the mains, but I made the switch to minidsp SHD as my pre to preserve my delicate sensibilities. I am sure the reality is that the ADC is less harmfull than a distorting small woofer trying to make real bass.
 

sarumbear

Master Contributor
Forum Donor
Joined
Aug 15, 2020
Messages
7,604
Likes
7,314
Location
UK
How did you come to these specific conclusions about diy folk? Experience?
Observance. A few examples:
  • Using a rectangular parallelepiped enclosure and placing the tweeter at the centre of the baffle. Olsen showed us 71 years ago that it is the worst possible enclosure shape and you will always have frequency response anomalies because of diffractions even if you have a drive unit with a ruler-flat frequency response. A rectangular truncated pyramid and parallelepiped combination (look at the link) is not difficult to achieve by a DIY carpenter or a small shop.
  • Using off-the-shelf crossovers that are designed for a fix, resistive load. Most tweeters have their fs around 1-2kHz. You think you are using a 2nd order, 2kHz crossover as that is what the label says but it will in fact be working at a different frequency and slope. That is because the impedance of the drive unit will be varying wildly around fs. You cannot design a crossover that can be used with any tweeter. It must be customised for each drive unit model. An off-the-shelf 2-way crossover is an engineering folly.
  • Ignoring the acoustical behaviour of a speaker in a room at frequencies below 70Hz and solely concentrating on the speaker's frequency response. (Post #41 is a good example.) At or below that frequency the response is mainly dictated by the room modes (standing waves) as the wavelength is similar to the listening room dimensions. Moving the listening position by a meter can easily cause a 6dB change in frequency response. A bass-trap will make much more affect on the frequency response than any electronic means. Why prioritise the speaker frequency response errors of a few dB in that range?
 
Last edited:

sarumbear

Master Contributor
Forum Donor
Joined
Aug 15, 2020
Messages
7,604
Likes
7,314
Location
UK
In my experience DIYers are always trying to learn something new and know/understand much more than typical "audiophile" consumers.
The issue is, there is almost nothing new to learn. Direct radiator loudspeaker behaviour had been analysed and papers published as long ago as 1951. Richard Small published his definitive thesis back in 1972 and his seminal set of papers soon after. We are talking knowledge that existed for half a century. All you need to do is to take a few courses in elementary physics and electronics, read Small's & Olsen's papers, then use a software to calculate the elements of your design.

Hobbyists often take courses in their interests like carpentry, welding, sewing, internal combustion engines, etc. I find it interesting that they do not do the same for speaker design? Because if they did conversations on this and other similar forums would be different. They wouldn’t be building speakers with obvious errors either.
 
Last edited:

Chrispy

Master Contributor
Forum Donor
Joined
Feb 7, 2020
Messages
7,751
Likes
5,910
Location
PNW
Observance. A few examples:
  • Using a rectangular parallelepiped enclosure and placing the tweeter at the centre of the baffle. Olsen showed us 71 years ago that it is the worst possible enclosure shape and you will always have frequency response anomalies because of diffractions even if you have a drive unit with a ruler-flat frequency response. A rectangular truncated pyramid and parallelepiped combination (look at the link) is not difficult to achieve by a DIY carpenter or a small shop.
  • Using off-the-shelf crossovers that are designed for a fix, resistive load. Most tweeters have their fs around 1-2kHz. You think you are using a 2nd order, 2kHz crossover as that is what the label says but it will in fact be working at a different frequency and slope. That is because the impedance of the drive unit will be varying wildly around fs. You cannot design a crossover that can be used with any tweeter. It must be customised for each drive unit model. An off-the-shelf 2-way crossover is an engineering folly.
  • Ignoring the acoustical behaviour of a speaker in a room at frequencies below 70Hz and solely concentrating on the speaker's frequency response. (Post #41 is a good example.) At or below that frequency the response is mainly dictated by the room modes (standing waves) as the wavelength is similar to the listening room dimensions. Moving the listening position by a meter can easily cause a 6dB change in frequency response. A bass-trap will make much more affect on the frequency response than any electronic means. Why prioritise the speaker frequency response errors of a few dB in that range?

Since it's bolded....what diy person would use an off the shelf crossover? I think that says a lot about your observations of the diy crowd....
 

sarumbear

Master Contributor
Forum Donor
Joined
Aug 15, 2020
Messages
7,604
Likes
7,314
Location
UK
Since it's bolded....what diy person would use an off the shelf crossover? I think that says a lot about your observations of the diy crowd....
I may well be wrong but can you tell me if they are not used by the DIYers who use these crossovers on the market as seen below?

Google shopping search, Amazon, eBay, etc.
 

Chrispy

Master Contributor
Forum Donor
Joined
Feb 7, 2020
Messages
7,751
Likes
5,910
Location
PNW
I may well be wrong but can you tell me if they are not used by the DIYers who use these crossovers on the market as seen below?

Google shopping search, Amazon, eBay, etc.

I didn't say some wouldn't buy that stuff, but generally the diy crowd that knows anything avoids such. I certainly can't think of ever discussing the use of such in diy discussions, altho do tend to warn off those who think you can use any box/driver/crossover you have on hand.....but I don't call that diy particularly....just random guessing maybe (outside of lack of knowledge in general).
 
Last edited:

sarumbear

Master Contributor
Forum Donor
Joined
Aug 15, 2020
Messages
7,604
Likes
7,314
Location
UK
I didn't say some wouldn't buy that stuff, but generally the diy crowd that knows anything avoids such. I certainly can't think of ever discussing the use of such in diy discussions, altho do tend to warn off those who think you can use any box/driver/crossover you have on hand.....but I don't call that diy particularly....just random guessing maybe (outside of lack of knowledge in general).
Just because you personally haven't seen discussed doesn't mean "in general" DIY speaker builders do not buy ready-made passive crossovers. Otherwise why would there be such a huge number of products on the market? As manufacturers wouldn't buy these, purely for economic reasons, who else are buying them?
PS. I am using the acronym DIY, for anyone who builds their own speakers using their own design (not from kit).
 
Last edited:

Chrispy

Master Contributor
Forum Donor
Joined
Feb 7, 2020
Messages
7,751
Likes
5,910
Location
PNW
Just because you personally haven't seen discussed doesn't mean "in general" DIY speaker builders do not buy ready-made passive crossovers. Otherwise why would there be such a huge number of products on the market? As manufacturers wouldn't buy these, purely for economic reasons, who else are buying them?
PS. I am using the acronym DIY, for anyone who builds their own speakers using their own design (not from kit).

Perhaps too broad a brush then. Usually in an audio forum when we discuss DIY we mean intelligent DIY. Not the random guessing of guys on a budget trying to make do with a box/driver/crossover they may have or will buy randomly. There's lots of people who are just not going to research, kinda like audiophiles....
 

sarumbear

Master Contributor
Forum Donor
Joined
Aug 15, 2020
Messages
7,604
Likes
7,314
Location
UK
Perhaps too broad a brush then. Usually in an audio forum when we discuss DIY we mean intelligent DIY.
Exceptions to the rule always exist. I am glad that you are one of them. However, that doesn't mean the rule is wrong.

As ASC does not have many DIY speaker design threads (there isn't even a speaker sub forum of DIY) I do not know much about the DIYers of this audio forum. However, there are lots of other forums, even specialised DIY speaker builder forums where links for ready-made passive crossovers are exchanged. That is the basis of my "broad brush".
 
Last edited:

Chrispy

Master Contributor
Forum Donor
Joined
Feb 7, 2020
Messages
7,751
Likes
5,910
Location
PNW
Exceptions to the rule always exist. I am glad that you are one of them. However, that doesn't mean the rule is wrong.

As ASC does not have many DIY speaker design threads (there isn't even a speaker sub forum of DIY) I do not know much about the DIYers of this audio forum. However, there are lots of other forums, even specialised DIY speaker builder forums where links for ready-made passive crossovers are exchanged. That is the basis of my "broad brush".

There's a general subforum for diy, though I haven't spent much time there. Other fora have diy sections that I've participated in, but the off the shelf crossovers generally don't come up but in the speaker/general subforums where someone wants to slap some new drivers and a crossover in a box willy nilly.....and the pre-made generic crossovers would be highly discouraged in those....
 

Duke

Major Contributor
Audio Company
Forum Donor
Joined
Apr 22, 2016
Messages
1,523
Likes
3,745
Location
Princeton, Texas
Sorry, maybe my misunderstanding, but pro woofers won't have necessarily less distortion, but higher power handling (i.e. more headroom before falling apart).

Prosound woofers are better at the things which I think matter most.

So even then, unless you have basically an integrated subwoofer (e.g. Salon 2), it would make sense to high-pass them; and possibly to turn a ported system into a "ported with an unexcited port" one.

With small woofers, there is arguably a lot more benefit from highpass filtering than with large woofers, whose excursion requirements are several times less to begin with.

And perhaps you find highpass filters to be completely transparent but I have high-end customers who do not, so I prefer to make the use of such filters optional.
 
Last edited:

Ron Texas

Master Contributor
Joined
Jun 10, 2018
Messages
6,078
Likes
8,914
If using stand mount mains a high pass on them will allow the system to play louder without bottoming out the mid/woofer. I'm running a 170 hz crossover point with LS50's and it works great. For this approach use 2 subs located near the mains and run them in stereo. The result is a full range speakers that go down all the way.
 

Chrispy

Master Contributor
Forum Donor
Joined
Feb 7, 2020
Messages
7,751
Likes
5,910
Location
PNW
If using stand mount mains a high pass on them will allow the system to play louder without bottoming out the mid/woofer. I'm running a 170 hz crossover point with LS50's and it works great. For this approach use 2 subs located near the mains and run them in stereo. The result is a full range speakers that go down all the way.

What subs do you have that cover the upper range that well?
 

Ron Texas

Master Contributor
Joined
Jun 10, 2018
Messages
6,078
Likes
8,914
What subs do you have that cover the upper range that well?
As it turns out I am able to do this with a pair of Rythmic L12's. I am likely getting some help from room gain. It also takes a lot of EQ. Recent SVS subs go higher. I took measurements with REQ and found the -6 dB point was 170 Hz and that's how I chose the crossover.
 

sarumbear

Master Contributor
Forum Donor
Joined
Aug 15, 2020
Messages
7,604
Likes
7,314
Location
UK
it would make sense to high-pass them; and possibly to turn a ported system into a "ported with an unexcited port" one.
Can you please explain what do you mean by "ported with an unexcited port" speaker?
 

Chrispy

Master Contributor
Forum Donor
Joined
Feb 7, 2020
Messages
7,751
Likes
5,910
Location
PNW
An example: SVS's specs for their SB/PB/PC 2000 Pro series show, on the high end, +/-3db to 290hz.
Yeah I have a couple subs good up that high too, was just curious what he had.
 

richard12511

Major Contributor
Forum Donor
Joined
Jan 23, 2020
Messages
4,335
Likes
6,700
If using stand mount mains a high pass on them will allow the system to play louder without bottoming out the mid/woofer. I'm running a 170 hz crossover point with LS50's and it works great. For this approach use 2 subs located near the mains and run them in stereo. The result is a full range speakers that go down all the way.

Indeed, and you'd have to spend many more thousands to get mains that dig down as low as moderately priced subs.
 
Top Bottom