Horn/Waveguide Questions

[mortron]

Hello all... Hope things are as well as possible given things.

As with many, I've been left ample time to ponder things and have a few burning questions regarding horns and waveguides. Unfortunately my experiences are limited and getting a frame of reference for how things sound is tricky at best.

Looking at the Yuichi A290 horn, the A480 and others of the sort has me wondering about how these sound compared to more modern waveguides like say the M2. I realize the horn and waveguide comparison is tricky, as they actually do different things in theory, but am wondering:

- how does the sound of a Yuichi type horn compare to that of a CD waveguide like the one found on the much more modern M2?

- I'm guessing directivity between the two types differ... Is there certain situations where one excels over the other?

- always considered the 1.4-1.5" throat drivers a good compromise between LF extension and HF... But don't see them used in the Yuichi type horns very much. Is there a reason?

- if going big like a 2", does the older 2445 function as we as more modern, non JBL offered drivers? Any merit to a coaxial in a Yuichi horn?

I'm not planning anything yet but trying to navigate all the options and compromises sometimes gives me more questions than answers. I understand different strokes and the sort, but just looking for a generalization of the differences, whether they're things you personally like/dislike or just general perceptions. Thanks in advance.

[JeffW]

The drivers with 2" exits like those that are used on the Yuichi have a different flare rate than the snout-less 1.5" exit drivers. I'm no expert, but it's my understanding that the flare rate of the horn and driver need to be compatible for best results.

[Robh3606]

Looking at the Yuichi A290 horn, the A480 and others of the sort has me wondering about how these sound compared to more modern waveguides like say the M2. I realize the horn and waveguide comparison is tricky, as they actually do different things in theory, but am wondering:

- how does the sound of a Yuichi type horn compare to that of a CD waveguide like the one found on the much more modern M2?

I can't say anything about the Yuichi but I do have the M2 waveguides and they are really nice and enjoyable to listen to.

- I'm guessing directivity between the two types differ... Is there certain situations where one excels over the other?

I prefer CD type horns/waveguides so I am biased. You really need to listen and decide for yourself, obviously both can sound very good but CD offers better off axis response.

- always considered the 1.4-1.5" throat drivers a good compromise between LF extension and HF... But don't see them used in the Yuichi type horns very much. Is there a reason?

I would guess the timeframe that it was developed in and what drivers were available at the time. All of the large 2" throated drivers are actually 1.4-1.5 when you remove the throat. Take a look at the 2450 vs 2450SL same exact driver except the SL is throatless. Another example is 2446 vs 2447 check the Library

http://www.lansingheritage.org/html/jbl/specs/pro-comp/pro-comp.htm

- if going big like a 2", does the older 2445 function as we as more modern, non JBL offered drivers? Any merit to a coaxial in a Yuichi horn?

The main difference between a 2445 and more modern drivers is the phase plug. It uses the older style like a 2441. All of the current large format drivers use some form of the Coherent Wave Phase Plug. That was first used in the 2446 CD.

Rob :)

[Ian Mackenzie]

Hello all... Hope things are as well as possible given things.

As with many, I've been left ample time to ponder things and have a few burning questions regarding horns and waveguides. Unfortunately my experiences are limited and getting a frame of reference for how things sound is tricky at best.

Looking at the Yuichi A290 horn, the A480 and others of the sort has me wondering about how these sound compared to more modern waveguides like say the M2. I realize the horn and waveguide comparison is tricky, as they actually do different things in theory, but am wondering:

- how does the sound of a Yuichi type horn compare to that of a CD waveguide like the one found on the much more modern M2?

It’s a subjective assessment and something you need to investigate personally. Not all people agree on what’s best subjectively. It can come down to how well either type is implemented and the impact of the listening room.

- I'm guessing directivity between the two types differ... Is there certain situations where one excels over the other?

The Yuich horns belong to the radial horn family with a particular flare rate. Typically they are 40 x 90 dispersion. In these designs fins with a particular geometric curve are used for dispersion along with the flare rate of the horn.

The wave guides use a diffraction shape of the horn throat adapter to shape the dispersion. The wave guides often have a rapid flare rate.

Sometimes a wide dispersion is advantageous but it depends on a number of factors such as your room acoustics. For example a Jbl use 60 x 90 dispersion in their consumer loudspeakers.

- always considered the 1.4-1.5" throat drivers a good compromise between LF extension and HF... But don't see them used in the Yuichi type horns very much. Is there a reason?

They are specifically designed for JBLs pro horns with rapid flare rates. The idea behind that was to maximise the flare rate in the horn throat so these drivers have a short throat. The driver resonance is much higher as a result.

- if going big like a 2", does the older 2445 function as we as more modern, non JBL offered drivers? Any merit to a coaxial in a Yuichi horn?

I would say no because those horns were designed around those drivers and the Tad 4001 drivers.
You need to have a deep understanding of how to implement the non Jbl coaxial drivers in order to make best use of these designs. It also depends on the aims of you overall loudspeaker design.

It’s subjective. Have a look at the Joseph Crowe YouTubes.

I'm not planning anything yet but trying to navigate all the options and compromises sometimes gives me more questions than answers. I understand different strokes and the sort, but just looking for a generalization of the differences, whether they're things you personally like/dislike or just general perceptions. Thanks in advance.

Your best to obtain a couple of different types and assess them yourself.
Some people rave about the old RCA drivers. Typically restricting the range of a horn or use of horns for different frequencies bands is helpful in diy audio. Attempting a wide range horn or wave guide requires a higher level of technical understanding and skill for a satisfactory result. Typically an additional high frequency driver above 8000 hertz will be more subjectively pleasing than attempting to equalise a waveguide or horn above these frequencies. Mass roll off occurs in any compression driver above 3000-4000 hertz at about 6 dB per octave. The way a compression driver and a horn or waveguide behaves at high frequencies does not necessarily live up to marketing claims.

My advice is not to expect too much out of a horn or a waveguide. For example don’t try and use a small horn or wave guide to crossover below 1000 hertz and don’t push it too high. A lot of these horns and wave guides are talk up on forum with nothing more than opinions without any practical experience with the horn or driver in question.

[mortron]

Thank you for the replies. Much of what you said confirms what I suspected.

When I look at it now, it's clear there are definitely trade-offs in many designs. Different time periods had different solutions to different problems. I would definitely like to try a 2" throws Yuichi at some point in the future as a long term goal of mine, if even just to hear one.

Is it fair to say the M2 waveguide is the culmination of all we have learned about waveguide technology to that point? I understand it's designed with a specific driver, but what about another JBL 1.5" driver? Would say a 2452 work well with the M2 guide? They're certainly much cheaper than they once were and tho still expensive, feel like the ask is worth it as far as what you get for the money. It's the implementation that is key tho, yes?

Choosing what to do is overwhelming. One could spend forever shopping for ingredients to a recipe that could turn out flopping. I try to see what works for others if even just for inspiration later down the road.

I used to be enamoured with the old woofers like 2235, but now see while they're great, newer drivers offer more in regards to refinement etc, and presume the same is true with the compression drivers, ya? I know the newer woofers have differential drive and the new compression drivers are something special, but do many of the legacy drivers hold a candle to them, or is it just chasing nostalgia? I notice the speakers Timbers made for his home use all modern (for the time) components... Even tho those are unattainable now too.

[ivica]

Hello all... Hope things are as well as possible given things.

As with many, I've been left ample time to ponder things and have a few burning questions regarding horns and waveguides. Unfortunately my experiences are limited and getting a frame of reference for how things sound is tricky at best.

Looking at the Yuichi A290 horn, the A480 and others of the sort has me wondering about how these sound compared to more modern waveguides like say the M2. I realize the horn and waveguide comparison is tricky, as they actually do different things in theory, but am wondering:

- how does the sound of a Yuichi type horn compare to that of a CD waveguide like the one found on the much more modern M2?

- I'm guessing directivity between the two types differ... Is there certain situations where one excels over the other?

- always considered the 1.4-1.5" throat drivers a good compromise between LF extension and HF... But don't see them used in the Yuichi type horns very much. Is there a reason?

- if going big like a 2", does the older 2445 function as we as more modern, non JBL offered drivers? Any merit to a coaxial in a Yuichi horn?

I'm not planning anything yet but trying to navigate all the options and compromises sometimes gives me more questions than answers. I understand different strokes and the sort, but just looking for a generalization of the differences, whether they're things you personally like/dislike or just general perceptions. Thanks in advance.

Hi mortron,

Yuichi A290 horn is internally consist of (I think) 5 small horns that would make good horizontal dispersion of the high frequency what is technical challenge while making standard horns. Usually a kind of diffraction slot is applied in the horn throat of such horn. Such type is much more difficultly to equalize, contrary to the A290 that has almost flat response from about 500Hz. So passive crossover network can be applied without any EQ.
I think using JBL aluminum diaphragm in to the drivers motors like 2446 or 2450 with A290 would satisfy all of You needs, so it would be possible to make a kind of 2-way system without many problems. Proper bass driver would be much more difficult to get. You can try 2216nd-1, 1500AL, 2235, mounted in the about 150 Lit bass-reflex box, with the crossover round 600Hz.
Some of the forum members are applied M2 horn with 2450SL/51 (476Be, 476Mg) with the satisfactory results, but a kind of UHF drivers are used. M2+D2 drivers can be applied too, but proper EQ must be applied.

regards
ivica

[Ian Mackenzie]

If you read the project M2 diy threads there is a lot of feedback there on various options with different drivers on the M2 horn. It requires an adapter.

But, be prepared to make a number of adjustments in order to equalise the horn correctly in the Dsp.

There is nothing clean cut about any of this and the end result is largely your perseverance.

It’s subjective as some people find the original Jbl drivers used in the M2 too detailed while others seen happy with it.

Read that thread carefully before you leap.

I personally would not embark on the M2 horn if it’s your first project.

There is a lot of head scratching details in setting up that wave guide with dsp.

You can get lost in the dsp trying to figure out where your going with measurements amd the subjective assessment.

Horns like the Yuichi and the improved Joseph Crowe horns are far more intuitive for diy purposes.
You don’t have to screw around with dsp endlessly and the learning curve that goes with it.


https://josephcrowe.com/collections/see-all/products/full-cad-cam-plans-for-es-290-biradial

[jmpsmash]

Thank you for the replies. Much of what you said confirms what I suspected.

When I look at it now, it's clear there are definitely trade-offs in many designs. Different time periods had different solutions to different problems. I would definitely like to try a 2" throws Yuichi at some point in the future as a long term goal of mine, if even just to hear one.

Is it fair to say the M2 waveguide is the culmination of all we have learned about waveguide technology to that point? I understand it's designed with a specific driver, but what about another JBL 1.5" driver? Would say a 2452 work well with the M2 guide? They're certainly much cheaper than they once were and tho still expensive, feel like the ask is worth it as far as what you get for the money. It's the implementation that is key tho, yes?

Choosing what to do is overwhelming. One could spend forever shopping for ingredients to a recipe that could turn out flopping. I try to see what works for others if even just for inspiration later down the road.

I used to be enamoured with the old woofers like 2235, but now see while they're great, newer drivers offer more in regards to refinement etc, and presume the same is true with the compression drivers, ya? I know the newer woofers have differential drive and the new compression drivers are something special, but do many of the legacy drivers hold a candle to them, or is it just chasing nostalgia? I notice the speakers Timbers made for his home use all modern (for the time) components... Even tho those are unattainable now too.

mortron, great fun to be building speakers. I have started late compare to the more experienced members here. One thing that I have learned is that while some of the older drivers have great reputation, their replacement parts are getting more and more difficult to find. So keep that in mind while trying to obtain discontinued drivers. You might end up having to do more work and money getting them fixed up.

[Robh3606]

There is a lot of head scratching details in setting up that wave guide with dsp.

You can get lost in the dsp trying to figure out where your going with measurements amd the subjective assessment.


Hello Ian

Not really with the 2450 series drivers. The M2 waveguide is not all that difficult to work with. With a passive network I was able to get a useable response with just 2 notch filters. A 2452 would be similar same with a 2453. You should able to set-up a similar result with DSP and possibly add a 3rd to bring up the last octave if needed. Here is an overlay POS did of the passive voltage drive vs the 2430 in the M2. As long as you are not looking for dead flat it should be fine.

Rob :)

[Robh3606]

[QUOTE]Is it fair to say the M2 waveguide is the culmination of all we have learned about waveguide technology to that point? I understand it's designed with a specific driver, but what about another JBL 1.5" driver? Would say a 2452 work well with the M2 guide? They're certainly much cheaper than they once were and tho still expensive, feel like the ask is worth it as far as what you get for the money. It's the implementation that is key tho, yes?[QUOTE]

Hello Morton

The M2 will work with the 2450 series drivers and 2452/2453. Using a passive network the only potential issue could be some last octave roll-off. Using DSP it would be no issue since you could bring the response up a bit if needed. It took only 2 notch filters to get a good passive solution. The transition with the woofer was more difficult. DSP should be similar as long as you are not going for ruler flat response.

No mater what horn/waveguide you use you will have to go through the same process. Measure, adjust and repeat as required.

Rob:)

[Ian Mackenzie]

Hi Rob,

If you are familiar and experienced with how to get to that point in the process Yes.

If your Not its a big ask in terms of learning how to do meaningful measurements and to drive and program DSP. Less than 1% of forum members understand how to make measurements. Probably a 1/10 of that have ever used DSP.

You have years of experience. We can’t assume that of the OP.

In my own experience as soon as l switch in Dirac to modify the response of an already flat response of a known loudspeaker you are playing God with the subjective presentation.

An on axis response measurement is not a strong indicator of how a CD wave-guide will work in a particular room. Often a flat response will sound too detailed in a typical consumer living space with a number of large flat surfaces. Real loudspeaker designs account for that. A conventional direct radiator system is more appropriate for on axis measurements. But the diy guy only thinks Flat response.

DSP is a big leap of faith in attempting a diy loudspeaker project. With the exception of home theatre l tread very carefully with EQ of any kind.

Edit . I just read your 2nd post.

If your out to have fun in diy (which we all are) and are not pitching for a superior nirvana presentation then what you end up with can be anything or anywhere as long as it goes as far as diy projects go.

If you want a superior nirvana presentation like a consumer design then it’s a more detailed and insightful journey requiring a lot of perseverance.

[JeffW]

[QUOTE]

The M2 will work with the 2450 series drivers and 2452/2453.


2450SL, not the vanilla 2450

The 2450SL is a 1.5" exit snoutless driver, the 2450 is a 2" exit driver with the flared snout.

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=82781&d=1542144167

[Robh3606]

Thanks your right should have been more specific! Would have to modify the mounting plate for a 2451 and countersink and use flathead screws to accommodate any of the large format drivers.

Rob:)

[Robh3606]

Hi Rob,

If you are familiar and experienced with how to get to that point in the process Yes.

If your Not its a big ask in terms of learning how to do meaningful measurements and to drive and program DSP. Less than 1% of forum members understand how to make measurements. Probably a 1/10 of that have ever used DSP.

You have years of experience. We can’t assume that of the OP.

Hello Ian

I would dispute those numbers. I think it's a bit higher than that. As far as DSP use almost all of the projects I have seen on this and other forums of late have been using DSP. I kind of feel like the forum dinosaur using passive networks in my DIY builds. That's just my preference and it's fun!

I don't want to lead anyone down the primrose path and leave them disappointed. If you have never done any DIY before start small and inexpensive while on the learning curve and work up to more difficult projects as you gain experience.

I understand the point you are making. I am not trying to make it look supper easy just saying what's possible. We are all adults here and capable of making decisions about what kind of risks we are willing to take based on personal experience, skill and perseverance.


An on axis response measurement is not a strong indicator of how a CD wave-guide will work in a particular room. Often a flat response will sound too detailed in a typical consumer living space with a number of large flat surfaces. Real loudspeaker designs account for that. A conventional direct radiator system is more appropriate for on axis measurements. But the diy guy only thinks Flat response.

Well I disagree on that point. CD systems have very predictable in room response and power response curves which make them much more room friendly than non CD systems. As far as cone and domes the Revels are all CD designs. They are all relatively flat or slightly tilted some rising in the last octave to get a "correct" power curve. The M2 is dead flat but it's a monitor not a home system.

Most cone and dome systems are not CD so in my mind they are where off axis measurements are most important for DIY. Any CD waveguide or horn will mirror the on axis response in the power response. So with CD if you get the on axis "right" off axis will follow over that portion of the response.

The biggest issue doing DIY waveguide and horns is getting the transition through crossover smooth between the LF driver and the Waveguide and looking off axis so you don't have an abrupt DI change. You really should have good off axis measurements for that.

I agree with flat may not be right. It's not for my DIY M2 system. I am using 1db or attenuation on the waveguide. That can be with any system CD or not CD. I think most people even with basic knowledge know this and would account for it doing a DIY system.

I don't think most DIY think only flat. It's the power curve that matters most for in room response look at the Array 1400 as an example of a non flat on axis to yield a flat in-room response. Maybe I assume people have more knowledge than they do but I think most people serious about DIY know this and also have read or know about Tooles book.


DSP is a big leap of faith in attempting a diy loudspeaker project. With the exception of home theatre l tread very carefully with EQ of any kind.

I can see minimizing DSP/EQ or simply not using from a purist point of view. Any DIY system is a leap of faith that will only be as good as the work you put into it.

DSP does has advantages especially if you know what you are doing. As far as how transparent they are?? I think we can all agree they are getting better and better. To some they have no issues at all to others they don't like what they here. Only you can decide for yourself.

Rob :)

[Ian Mackenzie]

Hello Ian


I understand the point you are making. I am not trying to make it look supper easy just saying what's possible. We are all adults here and capable of making decisions about what kind of risks we are willing to take based on personal experience, skill and perseverance.

Well I disagree on that point. CD systems have very predictable in room response and power response curves which make them much more room friendly than non CD systems. As far as cone and domes the Revels are all CD designs. They are all relatively flat or slightly tilted some rising in the last octave to get a "correct" power curve. The M2 is dead flat but it's a monitor not a home system.

Most cone and dome systems are not CD so in my mind they are where off axis measurements are most important for DIY. Any CD waveguide or horn will mirror the on axis response in the power response. So with CD if you get the on axis "right" off axis will follow over that portion of the response.

The biggest issue doing DIY waveguide and horns is getting the transition through crossover smooth between the LF driver and the Waveguide and looking off axis so you don't have an abrupt DI change. You really should have good off axis measurements for that.

I agree with flat may not be right. It's not for my DIY M2 system. I am using 1db or attenuation on the waveguide. That can be with any system CD or not CD. I think most people even with basic knowledge know this and would account for it doing a DIY system.

I don't think most DIY think only flat. It's the power curve that matters most for in room response look at the Array 1400 as an example of a non flat on axis to yield a flat in-room response. Maybe I assume people have more knowledge than they do but I think most people serious about DIY know this and also have read or know about Tooles book.

Rob :)

Hi Rob,

I think your post while well informed is too sweeping in your generalised view point of what people know or don’t know or should know if they are serious about diy.

So you saying you expect people to be aware of or have read Tooles book so they can understand your post? I haven’t read it.

I can say that people who are serious about diy in other words have the means are not necessarily tech savvy in a highly detailed sense. They are generally self aware enough to get trusted advice.

The issue with you is what you think people are expected to know about Tooles Book. That’s a bit arrogant.

If you were to rephrase that to l encourage people to read Tooles book on your journey to becoming serious about diy it might be better received.

[Robh3606]

Hi Rob,

I think your post while well informed is too sweeping in your generalised view point of what people know or don’t know or should know if they are serious about diy.

So you saying you expect people to be aware of or have read Tooles book so they can understand your post? I haven’t read it.

I can say that people who are serious about diy in other words have the means are not necessarily tech savvy in a highly detailed sense. They are generally self aware enough to get trusted advice.

The issue with you is what you think people are expected to know about Tooles Book. That’s a bit arrogant.

If you were to rephrase that to l encourage people to read Tooles book on your journey to becoming serious about diy it might be better received.

Hello Ian

Well I looked at your post about less that 1% knowing how to do a proper measurement as under estimating a persons knowledge and skills. My general view is people are a lot more knowledgeable than that. Every audio forum I have been on has had numerous discussions and still regularly do about Tooles book. So any poster or reader participating on any of these forums would have been exposed to these posts and at least be aware of the books existence.

It certainly is not a prerequisite for understanding my posts and at no time have I ever said that.

So I am not expecting anything beyond the exposure they would get from these discussions which are actually quite frequent.

If you think I am arrogant because I think people are more informed and capable than you seem to think I can live with that.

" But the diy guy only thinks Flat response."

JMHO Again under estimating knowledge and skills.

Rob :)

[Ian Mackenzie]

Hello Ian

Well I looked at your post about less that 1% knowing how to do a proper measurement as under estimating a persons knowledge and skills. My general view is people are a lot more knowledgeable than that. Every audio forum I have been on has had numerous discussions and still regularly do about Tooles book.

" But the diy guy only thinks Flat response."

JMHO Again under estimating knowledge and skills.

Rob :)

It’s not worth my time arguing about this.

However, if l took a Poll of how many people were not just aware of what an authentic FR measurement was (?) but how to make an authentic measurement to the accuracy you refer to and had enough skill and experience to do it reliably (and the right tools to do it with) it would be a small minority of Poll numbers. That l can state un categorically.

Most people don’t actually get into it. They might be aware of magazine curves and oh yeah l saw that but that’s it. We are not talking about Pink noise.

What is a ground plane measurement and when should it be used? What are the benefits and limitations of near field measurements? How do l interpret my measurements? How do l do a gated measurement? What is the difference between an MLS and a sine wave measurement? Do l need a calibrated microphone? How do l splice a port measurement with an on axis measurement? Why do l need to do a minimum phase transformation and tail correction when measuring a driver. What is the XYZ location and the reference position?

There are people who do post measurements but it’s a small minority of posters and a time portion of inactive posters and lurkers. Until you start making your own valid measurements it’s the blind leading the blind. You have to do it yourself.

I can say that because over that past five years l have had numerous requests to visit people who had no idea of how to do real meaningful measurements but after a discussion realised the importance of it in setting up their systems. From LA to Hong Kong the story is the same.

Did they know what REW is or had the desire or the means to make measurements. No. They certainly were smart and affluent. Even experienced aerospace engineer needed a hands on run through.

So l suggest you get some actual evidence to support your assumptions before you make those sort of generalisations.


Enjoy your weekend (Shrek)

Ian

[Ian Mackenzie]

I should point out this is not a judgement or selling forum members short but an observation in the field, in the trenches and getting down to the nitty gritty what what’s really happening with your own loudspeaker project.

I have been doing my own measurements for over ten years. The technology and the tools are becoming more accessible to the diy audio person and at much lower cost. An REW download is free and a Minidsp calibrated mic is just over $100.00 . Greg Timber’s recommends REW for setting up your projects BTW.

[Robh3606]

So l suggest you get some actual evidence to support your assumptions before you make those sort of generalisations.

How about just looking at the volume of measurements posted on the various forums.


I should point out this is not a judgement or selling forum members short but an observation in the field, in the trenches and getting down to the nitty gritty what what’s really happening with your own loudspeaker project.

Good glad to see that. I was talking about active forum members across the internet on DIY ASR AudioKarma Audioholics and so on. I was not talking about people in general who are interested but have no real exposure.

I freely admit you have more contact with people off the forums than I do so in that light I can understand what you are saying now.

Well gotta run

Rob :)

[mortron]

Man... I feel bad now. Jackie Moon says "Everybody Love Everybody!"

I guess it should be said that I'm not a very technically skilled person in regards to speaker design. Compared to a layperson, I probably sound super smart, and have had to correct them that I know nothing. That said, one (a guy who looks just like Shrek ironically) mentioned "why don't you go try to work for a speaker designer" to which I laughed, laughed some more, mentioned I haven't even read Toole's book and told him I want to be able to keep a roof over my head LOL. Though my day to day job isn't that speaker based, the theory is all built around RLC properties of materials, phase of signals etc passive crossovers kind of make sense. Or is it passive crossovers make my work make sense? Either way, I have a little relevant knowledge that is applicable, just not specific to speaker design.

The ability to properly measure is an art in itself. This is what keeps me looking for subjective opinions rather than just trying things. It's what keeps me from being semi legitimate as a tinkerer. I am on the fence about a mic... Calibrated MiniDSP mics are not in stock presently from Cross Spectrum. I was going to just buy a Dayton EMM6 from Solen to use as a stop gap. As I understand the calibration is most important in the higher end and working out basic crossover stuff can still be don't uncalibrated - just with some limited accuracy, yeah? I notice that when comparing mics the UMIK has some limitations the EMM6 did not. Regardless, once I get a mic I can seriously take part.

I've also spent like a decade hmm'ing and haww'ing about what to do, etc... Definitely understand many of the caveats and such involved. My visits to a friend who is constantly tuning his gear shows me that simply using proven or recommended products in a system does not instantly equal success. It's not lost on me when most suggest a proven kit for their first dip into speaker building.

In regards to DSP... I guess for me, there is two aspects. The purist who wants best possible single, and the tinkerer who wants the ultimate set of tools. Whilst DSP may not be a part of the final product, it's usefulness is undeniable in the design and testing stage. Much easier to try things on the fly, go back to older settings or save settings for later. I have a Driverack 260 I got for a song. It does a lot and doesn't sound half bad. A friend has the 4820 (irrc) and it looks much nicer on paper and definitely haven't heard of any issue with him using it in very high end setups. It's what inspired me to get my 260. That said, you get what you pay for. Good ADA conversion isn't free, and while plenty of options exist, I realize that as a technology, it's gotten really really good. I just can't afford that level of resolution at the moment. Using DSP to design analog filters is still something I've considered as a long term next step from a DSP speaker. Not always possible but never know till you try, design and as pointed out .. properly measure.

It sucks, my coworker went to visit the NRC and didn't even know what an anechoic chamber or a Floyd Toole was :D

In the end, it seems too that there are different goals, and design philosophies that each employ or practice that will put their ideas up against others. When it comes to something like sound, there is a lot of qualitative properties some will prefer over quantitative. Most I know don't care how flat their speaker is, they want bass, or clarity, etc. From a technical standpoint it's all relative to measurements but they don't phrase it like that. They speak in less technical terms. Maybe they just don't know what they're missing. I don't think there is going to be a lot of consensus on every point because there are so many points of compromise in audio reproduction. We've all seen those uncompromised systems and they're insane and definitely not free from criticism, yet probably sound better than much of what we have heard. Audio reproduction is about compromises. We already accept that we can't have them there live, so the recording is our best option.

[Robh3606]

Hello Mortron

Everyone has to start somewhere. The trick is just getting started in the first place and the rest will follow. You knowledge will grow you will become more comfortable as time goes on. There is a wealth of information out there and plenty of forums to reach out for help. The price of entry has dropped considerably and as Ian noted REV is great measurement system with a robust forum for support.


Rob:)

[DualTriode]

Thanks your right should have been more specific! Would have to modify the mounting plate for a 2451 and countersink and use flathead screws to accommodate any of the large format drivers.

Rob:)

Hello All,

Trying all the combinations of CD's and horns / waveguides is much of the fun of DIY.

Add in the equalization and DSP stuff there is so much fun that it gets a bit complicated.

Now that I have all this stuff on the shelf, I have a couple of recommendations.

Start out with a JBL 2451 J compression driver bought used for about $100 each on ebay and bolt on a PTH 1010 waveguide from from reconing speakers for near $63 each. with this combination of parts you have high quality / high tech that sounds pretty good all on its own. The flange of the waveguide fits inside the bolt circle of the driver add a washer at each of the 1/4" threaded studs and gently snug up the nuts

In my testing the JBL 2451 J and PTH 1010 waveguide plot as flat as the much higher price D2 driver and M2 waveguide combination.

Even a amplifier with tone controls get you close to functional equalization.

Thanks DT

If you have an interest I can post a Frequency Response and distortion plot. Plus a photo of CD attached to the waveguide.

[Ian Mackenzie]

Great to see your own practical experiments have lead some great outcomes.

If only more forum members did this rather than rely on other’s opinions or dissecting spec sheets looking for the perfect answer (itinerant wankers naval gazing for an improbable solution).

[Robh3606]

Hello DT

Not sure why you quoted my post? That is specifically about the M2 which uses a metal flange and does not have any predrilled holes for the larger diameter bolt drivers.

The PTH1010 works really well with the 1.5" 245X series drivers.

Post your measurements when you get time.

Rob:)

[ivica]

Hello All,

,,,,,,,,
In my testing the JBL 2451 J and PTH 1010 waveguide plot as flat as the much higher price D2 driver and M2 waveguide combination.

Even a amplifier with tone controls get you close to functional equalization.

Thanks DT

If you have an interest I can post a Frequency Response and distortion plot. Plus a photo of CD attached to the waveguide.

Hi DT,

It would be nice if You can show us teh measurements, and the compensation curve too.
regards
ivica

[sebackman]

I agee with much of the above. Personally I prefer the 4” drivers over D2.

A few comments.

Get 2451SL or 2452SL. 2453 does not work on these WG’s without a spacer. The first two are better drivers, pref 2451. I have all of them to compare.

Get one with an SL diaphragm or get an SL diaphragm and have it installed. They go all the way to 20kHz with some eq.

Get a BSS BLU-xxx DSP unit. Cheap on the Bay. Better algorithms than most others, albeit similar performance HW.

if you use a DSP with analog input, make certain that input level is high so the ADC have someting to work with. Alternatively feed it digital signal (BLU-USB ??)

Get the newer VTX F12/F15 wave guide, better than the older PT-xxxx, even if the look very similar. Cheap and efficient. Measures great too. Cool with wooden horns but these sound better IMHO.

These WG`s need very little correction in the DSP and XO at 900-1kHz 24LR will only require 2 EQ points to get you most of the distance. The rest you can introduce over time when you can measure. Many of us are familiar with BSS programming and can email a start setup file.

You can of course go passive but it will probably cost the same in the end and does not allow for improvement as environment, skills and taste evolves.

if you want to build a two-way system the woofer needs to be able to meet the horn in a good manor. That restricts the choise. 2235, albeit an excellent woofer, would probably not be the choice. Go 2216 ( or similar newer woofer) or go 12”. Or use a mid bass like a 1400Pro and a sub.

My 25 cents

kind regards and Happy 4th of July
//Rob

[srm51555]

if you use a DSP with analog input make certain that input level is high so the ADC have someting to work with. Alternatively feed it digital signal (BLU-USB ??)


+1. if you go the BSS route you can also use one of the contrio controls in place of a pre-amp.

[ivica]

I agee with much of the above. Personally I prefer the 4” drivers over D2.

A few comments.

Get 2451SL or 2452SL. 2453 does not work on these WG’s without a spacer. The first two are better drivers, pref 2451. I have all of them to compare.

Get one with an SL diaphragm or get an SL diaphragm and have it installed. They go all the way to 20kHz with some eq.

Get a BSS BLU-xxx DSP unit. Cheap on the Bay. Better algorithms than most others, albeit similar performance HW.

if you use a DSP with analog input, make certain that input level is high so the ADC have someting to work with. Alternatively feed it digital signal (BLU-USB ??)

Get the newer VTX F12/F15 wave guide, better than the older PT-xxxx, even if the look very similar. Cheap and efficient. Measures great too. Cool with wooden horns but these sound better IMHO.

These WG`s need very little correction in the DSP and XO at 900-1kHz 24LR will only require 2 EQ points to get you most of the distance. The rest you can introduce over time when you can measure. Many of us are familiar with BSS programming and can email a start setup file.

You can of course go passive but it will probably cost the same in the end and does not allow for improvement as environment, skills and taste evolves.

if you want to build a two-way system the woofer needs to be able to meet the horn in a good manor. That restricts the choise. 2235, albeit an excellent woofer, would probably not be the choice. Go 2216 ( or similar newer woofer) or go 12”. Or use a mid bass like a 1400Pro and a sub.

My 25 cents

kind regards and Happy 4th of July
//Rob

Hi sebackman,

Very friendly and useful post, that would give far less try-and-error results.

Regards
Ivica

[Robh3606]

2453 does not work on these WG’s without a spacer.

Hello Sebackman

Which waveguides have you seen issues with? I had no issues at all on PTH1010. Measured fine sounds great!

Rob:)

[sebackman]

Hi Rob,

The newer VTX WG has a better high end and better horn load in the low segment. I think I have posted a comp earlier. -Will see if I can find the comp file.

Can it be fixed with DSP? Absolutely, but given a choise with no price difference why would you not get the better start?

kind regards
//Rob2

[ivica]

Hi Rob,

The newer VTX WG has a better high end and better horn load in the low segment. I think I have posted a comp earlier. -Will see if I can find the comp file.

Can it be fixed with DSP? Absolutely, but given a choise with no price difference why would you not get the better start?

kind regards
//Rob2

Hi

Talking about STX 825
https://jblpro.com/zh/products/stx825
(https://jblpro.com/zh/products/stx825)https://reconingspeakers.com/product/jbl-horn-lens-5006815-stx825/


Regards
Ivica

[sebackman]

Hi everyone,

Yes Ivica, they look the same but they are not. I have really sold all my vintage and other "high end" horn/waveguides and only use these or the M2 (and soon the 4367). If you can handle that they are ugly, cheap, plastic (not nice wood or cast metal) and with limited "show-off factor", they really out perform most alternatives on the market for a song. Slab some vibration damper material (rubber or similar) on the outside of the plastic plastic and make a sturdy driver support in the cabinet and you are good to go. At least with 2450SL, 2451SL and 2452SL. 2453 will need a spacer and the goes for 243X. Same problem on the M2, a nasty resonance in the throat at 10k.

Older PT's are also good, no doubt. With some additional EQ and measuring I guess you can potentially get to the same point. These are just a newer version.

If you do go the 4" SL route, which I strongly suggest, get new diaphragms as older may be out of spec dependent on prior use.

I also suggest to open the back cover on drivers prior to purchasing to check for corrosion in the drivers. If the have been in PA operations they may have been in stage monitors that from time to time get water in the horn entrance or may have been subjected to condensation at outdoors events. If the driver is rusty under the rear cover (you normally do not need to remove the diaphragm to see it) I would stay away as my experience show that it is very difficult to get them to perform. If the pole piece is corroded that often means that there may be corrosion in the phasing plug and that cannot be cleaned without dismantling the entire driver. A hve bought many "bargain" drivers that turned out to be beyond HiFi use. PA probably fine but not for critical listening.

Another topic I have not seen mentioned here at LHF is Neodym magnet rot. The older JBL drivers used Neodym magnet material that also tend to corrode/rot in certain environments. This materializes as small magnetic fragments in the coil gap and regardless how many times you clean they keep coming back. This means that the magnet is beyond salvage. I have had this on a few 2450SL/2451 drivers that had to be canned. I have also had it on a few older Neodym woofers like the 1400PRO (currently 3 dead basked in the shop). JBL knows of the problem and has also replaced a bunch back when.

My 25 cents

//Rob

[Riley Casey]

Well this is interesting. I've got a fair number of Neo drivers in various JBL boxes some coming up on twenty years old. Can you point me at any documentation on the Neo 'rot' issue?


Hi everyone,

...
Another topic I have not seen mentioned here at LHF is Neodym magnet rot. The older JBL drivers used Neodym magnet material that also tend to corrode/rot in certain environments. This materializes as small magnetic fragments in the coil gap and regardless how many times you clean they keep coming back. This means that the magnet is beyond salvage. I have had this on a few 2450SL/2451 drivers that had to be canned. I have also had it on a few older Neodym woofers like the 1400PRO (currently 3 dead basked in the shop). JBL knows of the problem and has also replaced a bunch back when.

My 25 cents

//Rob

[engineerjoe]

I've got a set of 2430h drivers that have the magnet rot thing. I cleaned the gap as best I could and they now work. They don't perform that well to my ears. I think the rot continues and I would have to continually clean them as they degrade further over time. So they are sitting on a shelf here. The diaphragms look OK but the drivers do not. I don't have any test equipment.

[rubjel]

Hi everyone,

Yes Ivica, they look the same but they are not. I have really sold all my vintage and other "high end" horn/waveguides and only use these or the M2 (and soon the 4367). If you can handle that they are ugly, cheap, plastic (not nice wood or cast metal) and with limited "show-off factor", they really out perform most alternatives on the market for a song. Slab some vibration damper material (rubber or similar) on the outside of the plastic plastic and make a sturdy driver support in the cabinet and you are good to go. At least with 2450SL, 2451SL and 2452SL. 2453 will need a spacer and the goes for 243X. Same problem on the M2, a nasty resonance in the throat at 10k.

Older PT's are also good, no doubt. With some additional EQ and measuring I guess you can potentially get to the same point. These are just a newer version.

If you do go the 4" SL route, which I strongly suggest, get new diaphragms as older may be out of spec dependent on prior use.

I also suggest to open the back cover on drivers prior to purchasing to check for corrosion in the drivers. If the have been in PA operations they may have been in stage monitors that from time to time get water in the horn entrance or may have been subjected to condensation at outdoors events. If the driver is rusty under the rear cover (you normally do not need to remove the diaphragm to see it) I would stay away as my experience show that it is very difficult to get them to perform. If the pole piece is corroded that often means that there may be corrosion in the phasing plug and that cannot be cleaned without dismantling the entire driver. A hve bought many "bargain" drivers that turned out to be beyond HiFi use. PA probably fine but not for critical listening.

Another topic I have not seen mentioned here at LHF is Neodym magnet rot. The older JBL drivers used Neodym magnet material that also tend to corrode/rot in certain environments. This materializes as small magnetic fragments in the coil gap and regardless how many times you clean they keep coming back. This means that the magnet is beyond salvage. I have had this on a few 2450SL/2451 drivers that had to be canned. I have also had it on a few older Neodym woofers like the 1400PRO (currently 3 dead basked in the shop). JBL knows of the problem and has also replaced a bunch back when.

My 25 cents

//Rob

Hi Rob,

can you please share the p/n's for this new generation of PT waveguides, and where to get them?
Looking at the link Ivica posted, this is an older version of the VTX F12 waveguide?
I was about to purchase this and the PTH-1010HF-1 from the Speaker Exchange :)

[DualTriode]

Hello All,Lately I have been trying to settle on a CD / waveguide combination. I seem to like the JBL D2 2430H CD and the current version of the rectangular PT95 90 X 50 degrees. The thinking is that there is less reflection off the walls and especially less off the floor and ceiling.See the attached on axis FR plots and distortion plots attached below.Thanks DT

[1audiohack]

Hello DT.

Is that wave guide PN5006815?

There is an issue with attachments that can be worked around in settings.

I haven’t tried yet so I will see if I can send this to you so we can see what you have attempted to attach.

https://www.audioheritage.org/vbulletin/attachment.php?attachmentid=91294&stc=1&d=1669352772

Barry.

[Ian Mackenzie]

Hello All,Lately I have been trying to settle on a CD / waveguide combination. I seem to like the JBL D2 2430H CD and the current version of the rectangular PT95 90 X 50 degrees. The thinking is that there is less reflection off the walls and especially less off the floor and ceiling.See the attached on axis FR plots and distortion plots attached below.Thanks DT


https://www.diyaudio.com/community/threads/best-compression-drivers-today-2022.382609/page-26

So are you saying your guessing these ceiling reflections or you can measure it?

If you are using REW you can factually determine the 1st reflection points in any room with appropriate measurements. REW can also accurately model your room reflection points and room modes.

Another way is to measure the vertical polar pattern and then work out where the 1st reflection point actually is off the ceiling.

Hint. This is why 90 x 40 radial horns have found favour in certain situations.

Depending on the degree of controlled directivity in the 90 x 50 wave guide and your listening distance of those 1st reflections given your ceiling height will be a problem or not with the direct sound from the on axis.

For example if your listening distant is 2 metres and the ceiling is 2 metres above your ears the reflected path length will be more than 4 metres.

Edit my post got chopped

What l was going to suggest is to try the psycho acoustic smoothing function is the REW measurements. That filter provides a good indicator of what really matters. In other words aspects of your measurements require attention.

In a domestic situation most if not all people put up with 1st reflections because they don’t have a choice without installing acoustic panels. It’s a first world problem.

By selecting a particular listening position you maybe able to reduce the impact of ceiling 1st reflections. Typically this means listening closer to the loudspeaker than you might otherwise do without making some informed decisions.

Good luck

Ian