Horn/Waveguide Questions

[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

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