Frequency response is everything!?...

[Tim Link]

Tim, line array horns? Other than from PRO/PA world, I haven't stumbled on that, could you elaborate pls.

Yes, I've got stacks of folded horn cabinets in each corner of my room that go up to the ceiling. They are comprised of four triangular cabinets that each have an 18" woofer, with a split path folded horn path that merges toward the end to come out the center. The wiring is series parallel so each stack of four horn woofers is powered from a single amp channel. Viewed from the top the cabinets are sort of heart shaped. The effective path length is about 6 feet. The idea here was to combine the four horn mouths with the corner of the room to get horn loading down below 30 Hz. They succeed at that, and I think would go lower if it weren't for limited back chamber volume. According to horn resp. simulation the back chamber volume is the limiting factor. To add volume would have made the speakers too big. However, since I'm no longer using the midrange horns that are sandwiched in the middle of each woofer stack, I could add some volume by pulling the mid horns out and sealing up the opening with a panel. I might try that some day. The back chamber volumes are all connected when the cabinets are stacked in place, and they also connect to the area behind the mid horn. I don't think it'd make a huge difference.

 

[Salectric]

Wow! That is some speaker!

 

[Tim Link]

Wow! That is some speaker!

Thanks! One of the surprising things about putting these in the corners is that they make the room look better! I've been told this by various family members and friends. I have to give credit to my friend Gavin Donahue who did most of the design and woodwork on these, with me assisting as I could. Gavin died about a year later from kidney cancer, or so I'm told. Unfortunately he got angry at me for not keeping the tooling we used to make these, along with other issues, and cut off all contact with me. He put a lot of work into these and they meant a lot to him. I did keep all the drawings and notes, and a bunch of photos and videos of some of the processes, but the tooling was just too much for me to store, and truthfully needed to be re-built if we were ever to make another set. If I had to do this again there'd certainly be changes which would require some testing to figure out, so new tooling would be in order regardless.
The accuracy to which he built these cabinets is pretty amazing. When I moved, my helpers were astounded how perfectly the cabinets could be stacked neatly into each other in a variety of different ways to fit best on the truck.

 

[Solypsa]

Yes, I've got stacks of folded horn cabinets in each corner of my room that go up to the ceiling. They are comprised of four triangular cabinets that each have an 18" woofer, with a split path folded horn path that merges toward the end to come out the center. The wiring is series parallel so each stack of four horn woofers is powered from a single amp channel. Viewed from the top the cabinets are sort of heart shaped. The effective path length is about 6 feet. The idea here was to combine the four horn mouths with the corner of the room to get horn loading down below 30 Hz. They succeed at that, and I think would go lower if it weren't for limited back chamber volume. According to horn resp. simulation the back chamber volume is the limiting factor. To add volume would have made the speakers too big. However, since I'm no longer using the midrange horns that are sandwiched in the middle of each woofer stack, I could add some volume by pulling the mid horns out and sealing up the opening with a panel. I might try that some day. The back chamber volumes are all connected when the cabinets are stacked in place, and they also connect to the area behind the mid horn. I don't think it'd make a huge difference.
View attachment 115016

Wow. Wow. What are you using for
mids if not what is pictured?

 

[Tim Link]

Wow. Wow. What are you using for
mids if not what is pictured?

What I'm doing lately is an experimental and highly unorthodox arrangement with a derived center channel. This uses 3 little cheap bookshelf speakers (for now) in the center using a matrix of L-R, L+R, R-L signal mixing to create a crosstalk canceling effect. This provides a suprisingly excellent and wide soundstage, with great purity of center panned images since they are entirely extracted from the two side channels and play exclusively from the center speaker. This array works down to around 600Hz. Below that the little speakers are too close together and the waves start to merge. So, from 600Hz on down the big horns take over. This provides a very wide spacing for lower frequencies, and narrower spacing with crosstalk reduction for higher frequencies. It's surprising just how good these little Sony speakers can sound when they're crossed over at 600 Hz in an array like this. I had read years ago that lower frequency drivers should be spaced apart further than higher frequency drivers for a more even stereo effect. The lower frequencies rely almost entirely on phase difference across the head to get a directional effect. In a standard listening triangle the high frequencies are too far apart, causing a comb filtering effect in each ear. The low frequencies are too close, not able to create much of a phase or volume difference across the head. This current setup creates a deep, clear and even soundstage across the room in front of me when sitting in the middle.

Our original plan for these speakers was to include a center channel, much like Klipsch had the Belle to go between the Klipschorns, which he recommended set widely spaced on the long wall of a room. I wasn't sure how to implement a center channel. I stumbled into this 3 closely spaced speaker array on accident. I thought that it might create somewhat of a stereo image, but would require the speakers to be exactly ear distance apart to work. To my surprise it works amazingly well up to three times that spacing when the listening position is far enough back. I think from some experiments and wave interference simulations that ideally the spacing should be about 1 foot above 1500 Hz, about 2 feet between 600 and 1500Hz, and then just go regular stereo spaced very widely below that. My tentative plan is to replace the bookshelves with constant directivity horns spaced about 1 foot center to center covering down to 1500 Hz, and then bigger horns on the floor below them spaced about 2 feet center to center. The lower crossover for those will depend on how they sound, but could be as low as 200 perhaps. In any case I feel I'll be sticking with this 3 speaker anti-crosstalk array from here on out. It's currently sounding good enough that I'm not in any particular hurry to improve it. The 3 speaker array is hiding in the cabinet below the TV! It's ridiculously good sounding for what it is. It's hard to believe that all the highs are coming out of those things. To my ears it's magic. Neither the old TV cabinet, the big flat screen TV above them, or the wall not far behind my head seem to be able to disturb the imaging. It's very robust. The speakers are all disappearing as well as I've ever heard. I think I'll replace the curtain the cat wrecked before I do anything else.

 

[Solypsa]

So cool

 

[Ampexed]

To designers of equipment, especially speakers, knowing what the frequency response is is vital. Flat frequency response is speakers is not necessarily the goal, which is why manufacturers spend a great deal of time 'voicing' their speakers, but measurements still save untold amounts of guesswork, even if the ultimate goal is to not have 'ideal' measurements.

I don't believe measurements are useful for end users at all, especially since they can be easily manipulated.

 

[schlager]

Thanks Tim, that clarifies things, nice bass horns. Placing them in the corners certainly helps with the loading and each hornmouth support each other for further loading. I use same principal (FLH) down to 20 Hz, works like a charm but gets awfully big.

 

[Ron Resnick]

I don't believe measurements are useful for end users at all, especially since they can be easily manipulated.

Frequency response measurements are one of the very few measurable and repeatable things in this subjective hobby. How can an external microphone, on a microphone stand at the listening position, fed to a real time analyzer, not be useful to an audiophile "at all"?

 

[Ampexed]

Frequency response measurements are one of the very few measurable and repeatable things in this subjective hobby. How can an external microphone, on a microphone stand at the listening position, fed to a real time analyzer, not be useful to an audiophile "at all"?

Because even speakers with outwardly 'identical' frequency responses still can sound very different. Things like dispersion, crossover frequencies, resonances, size of cabinets (and size of the sound source) etc make just as much difference as raw response, and those things are difficult for non-engineers to interpret accurately.

 

[Atmasphere]

Frequency response measurements are one of the very few measurable and repeatable things in this subjective hobby. How can an external microphone, on a microphone stand at the listening position, fed to a real time analyzer, not be useful to an audiophile "at all"?

Actually it is. Pink noise in a room makes it easier to set up speakers. I know a couple of audiophiles that use it for that purpose and I would not describe them as engineers even remotely. These days its pretty easy to do that with an app on a digital device like an iPad.

 

[Ampexed]

Actually it is. Pink noise in a room makes it easier to set up speakers. I know a couple of audiophiles that use it for that purpose and I would not describe them as engineers even remotely. These days its pretty easy to do that with an app on a digital device like an iPad.

I was originally speaking about the lack of utility with manufacturers publishing measurements in their advertizing - not to be confused with end users making measurements of already purchased speakers in one's room for purposes of tuning using something like REW.

 

[Carlos269]

What I'm doing lately is an experimental and highly unorthodox arrangement with a derived center channel. This uses 3 little cheap bookshelf speakers (for now) in the center using a matrix of L-R, L+R, R-L signal mixing to create a crosstalk canceling effect. This provides a suprisingly excellent and wide soundstage, with great purity of center panned images since they are entirely extracted from the two side channels and play exclusively from the center speaker. This array works down to around 600Hz. Below that the little speakers are too close together and the waves start to merge. So, from 600Hz on down the big horns take over. This provides a very wide spacing for lower frequencies, and narrower spacing with crosstalk reduction for higher frequencies. It's surprising just how good these little Sony speakers can sound when they're crossed over at 600 Hz in an array like this. I had read years ago that lower frequency drivers should be spaced apart further than higher frequency drivers for a more even stereo effect. The lower frequencies rely almost entirely on phase difference across the head to get a directional effect. In a standard listening triangle the high frequencies are too far apart, causing a comb filtering effect in each ear. The low frequencies are too close, not able to create much of a phase or volume difference across the head. This current setup creates a deep, clear and even soundstage across the room in front of me when sitting in the middle.

Our original plan for these speakers was to include a center channel, much like Klipsch had the Belle to go between the Klipschorns, which he recommended set widely spaced on the long wall of a room. I wasn't sure how to implement a center channel. I stumbled into this 3 closely spaced speaker array on accident. I thought that it might create somewhat of a stereo image, but would require the speakers to be exactly ear distance apart to work. To my surprise it works amazingly well up to three times that spacing when the listening position is far enough back. I think from some experiments and wave interference simulations that ideally the spacing should be about 1 foot above 1500 Hz, about 2 feet between 600 and 1500Hz, and then just go regular stereo spaced very widely below that. My tentative plan is to replace the bookshelves with constant directivity horns spaced about 1 foot center to center covering down to 1500 Hz, and then bigger horns on the floor below them spaced about 2 feet center to center. The lower crossover for those will depend on how they sound, but could be as low as 200 perhaps. In any case I feel I'll be sticking with this 3 speaker anti-crosstalk array from here on out. It's currently sounding good enough that I'm not in any particular hurry to improve it. The 3 speaker array is hiding in the cabinet below the TV! It's ridiculously good sounding for what it is. It's hard to believe that all the highs are coming out of those things. To my ears it's magic. Neither the old TV cabinet, the big flat screen TV above them, or the wall not far behind my head seem to be able to disturb the imaging. It's very robust. The speakers are all disappearing as well as I've ever heard. I think I'll replace the curtain the cat wrecked before I do anything else. View attachment 115041

With the matrix and derived center-channel, you are progressing in the right direction if dimensional sound is the goal. I have had great success with a similar approach, with just the two stereo channels.

 

[Tim Link]

Frequency response in conjunction with timing in

With the matrix and derived center-channel, you are progressing in the right direction if dimensional sound is the goal. I have had great success with a similar approach, with just the two stereo channels.

Is there a thread where you talk about how you set up your system? My inspiration for a long time now has been the sound I heard the several times I successfully set up a crosstalk barrier. That set the bar for what how I want my system to sound. I don't like having a barrier in my face. I've played with some DSP implementations, Polk SDA, and Carver's Sonic Holography. None of those worked to my satisfaction in my attempts at using them, although I'm sure I didn't get them set up to their best potential. The barrier is the one method that cleans up the signal reaching the ear without any need for signal processing.

 

[Bjorn]

Flat and even response are two different things and often mixed wrongly by people. No one in the industry is saying that a complete flate response with same level at all frequencies is desirable. A neutral response and all standards we have have a type of response that falls towards the treble.

But having an even response is very important to achieve correct tonality. On the other hand, it matters greatly how you get there. Simply making an even response with EQ/DSP will introduce a lot of artifacts and isn't a good choice for correct sound.

 

[schlager]

Simply making an even response with EQ/DSP will introduce a lot of artifacts and isn't a good choice for correct sound.

Agreed, that if one is not careful the cure can be worse than the disease, but I find that with the best DRC programs using FIR and clever psycho acoustic algorithms, the perspective is changing quite a bit. Combined with some acoustic treatments, the results gets even better. I just can´t see why a recovery of the impulse response is a bad thing. In the end your ears have to decide.

 

[microstrip]

Frequency response measurements are one of the very few measurable and repeatable things in this subjective hobby. How can an external microphone, on a microphone stand at the listening position, fed to a real time analyzer, not be useful to an audiophile "at all"?

When the technique used to acquire the data is inadequate or poorly known the measurements can be misleading.

BTW, in order to define the utility of any measurement you must specify your purpose and how you are using it. Otherwise it is just clamorous talk.

 

[Atmasphere]

In case its not clear at this point, FR isn't everything.

One thing that is often left out in a discussion like this is that the ear/brain system converts distortion into tonality, and gives that tonality a fair amount of weight, sometimes overshadowing FR. This should not be controversial in any way: the ear uses harmonics to distinguish musical instruments after all...

My point here is the distortion of the system is responsible for how the system sounds as well as it changes the sound of musical instruments by adding harmonics. Quite literally the 'sonic signature' of a preamp or amplifier is in fact its distortion signature. This is the traditional source of brightness and harshness in solid state amps and the 'warmth' of tube amplifiers.

Solid state amps usually have quite a lot less distortion than tube amps, but since they make less lower ordered harmonics per capita than tube amps, their higher ordered harmonic content is not masked. The ear uses higher ordered harmonics to sense sound pressure and since the ear has a +120dB range, its keenly sensitive to their presence. This simple fact is why tube amplifiers have stayed around in audio while clearly obsolete in the rest of the electronics world. Fortunately class D has finally offered a method of getting around this issue; putting tube amps on borrowed time, for those who find brightness and harshness to be one of the greater sins of commission.

So when describing the sound of a system, the simple fact is you are describing both FR and distortion.

 

[hopkins]

In case its not clear at this point, FR isn't everything.

One thing that is often left out in a discussion like this is that the ear/brain system converts distortion into tonality, and gives that tonality a fair amount of weight, sometimes overshadowing FR. This should not be controversial in any way: the ear uses harmonics to distinguish musical instruments after all...

My point here is the distortion of the system is responsible for how the system sounds as well as it changes the sound of musical instruments by adding harmonics. Quite literally the 'sonic signature' of a preamp or amplifier is in fact its distortion signature. This is the traditional source of brightness and harshness in solid state amps and the 'warmth' of tube amplifiers.

Solid state amps usually have quite a lot less distortion than tube amps, but since they make less lower ordered harmonics per capita than tube amps, their higher ordered harmonic content is not masked. The ear uses higher ordered harmonics to sense sound pressure and since the ear has a +120dB range, its keenly sensitive to their presence. This simple fact is why tube amplifiers have stayed around in audio while clearly obsolete in the rest of the electronics world. Fortunately class D has finally offered a method of getting around this issue; putting tube amps on borrowed time, for those who find brightness and harshness to be one of the greater sins of commission.

So when describing the sound of a system, the simple fact is you are describing both FR and distortion.

It is like changing seats in a concert hall. Each seat may give you a slightly different sound, with a different frequency response, and acoustical imperfections, but you still know you are listening to a live event and can enjoy it.

 

[Atmasphere]

It is like changing seats in a concert hall. Each seat may give you a slightly different sound, with a different frequency response, but you still know you are listening to a live event and can enjoy it.

What are you talking about? IOW, its not clear to me why you quoted me and wrote that.