A good tweeter to match 5" SB Acoustics Magnesium Woofers

[DDF]

You are 100% right, I was wrong, you guys should go about your buisness. If I ever have time to prove to you what I hear from this
type of filter/pad I will let you know. In the mean time please keep crossing tweeters over so close to the Fs not mindful of the transfer function.

Anybody interested in my findings with the Viawave etc, you know how to find me.

I think you've been treated poorly and unfailry and dealt with the situation with good humour.

FWIW I haven't heard the speaker in question, but for my own designs, such a tweeter filter with such a rise at knee gives a good line on a graph at one point in space because it equalizes for diffraction at one point in space. However IME on my speakers it dumps too much energy into the room at those frequencies, especially given the tweeter has such wide dispersion in that range.

In a large room (such as those at the DIY meets where most people get to share designs) it may not be so audible because the reflection delay is so great, but in a small room IME on my experiments with similar drivers/layouts its grating and etched.

[xmax]

The only reason I brought it up was because I was very happy the first time I tried something like that, I was very happy
with the measured results and kept trying to talk myself into it sounding good but it did just not. With a beautiful 4"
woofer why even think about running the tweeter that low! Also Brian at Madisound always grounds me with his
blunt truth. I tried pulling a fast one with the TW29B and he was kind enough to remind me I had my clown shoes on.

[xmax]

It could also have something to do with transient behavior I haven't looked at the scope yet.
You talk about cap/coil ratios around here and you are greeted with the dull lifeless eyes
of a mannequin.

[DDF]

The only reason I brought it up was because I was very happy the first time I tried something like that, I was very happy
with the measured results and kept trying to talk myself into it sounding good but it did just not. With a beautiful 4"
woofer why even think about running the tweeter that low! Also Brian at Madisound always grounds me with his
blunt truth. I tried pulling a fast one with the TW29B and he was kind enough to remind me I had my clown shoes on.

Think about it. If at 4 db lower levels it sounds bad compared to the same design without the tweeter bump and the woofer equed to fill, its not distortion 9tweeter isn't playing any louder). IME after zillion of xovers over 30 yrs, its the dispersion.

[xmax]

Think about it. If at 4 db lower levels it sounds bad compared to the same design without the tweeter bump and the woofer equed to fill, its not distortion 9tweeter isn't playing any louder). IME after zillion of xovers over 30 yrs, its the dispersion.

Perhaps clarify that for the rocket scientist around here.

[craigk]

It could also have something to do with transient behavior I haven't looked at the scope yet.
You talk about cap/coil ratios around here and you are greeted with the dull lifeless eyes
of a mannequin.

Please explain this ratio and poi nt me in the direction where I can read about it. I am not sure how you do this since every tweeter os different and the cross over points are infinite with all the different roll offs. Maybe there is a generic rule ?

[dlr]

Think about it. If at 4 db lower levels it sounds bad compared to the same design without the tweeter bump and the woofer equed to fill, its not distortion 9tweeter isn't playing any louder). IME after zillion of xovers over 30 yrs, its the dispersion.

I don't recall him having made any comments related to dispersion, something that I seriously would expect Jeff to have taken into account during design.

There's an issue that has not been discussed at all that is critical in all of this discussion. The argument made was that placing a resistor after a crossover (2nd order electrical only being considered) was not just problematic, but to be avoided in all cases. The measurements shown were for precisely that (simply sticking a rresistor into the XO) and used for the negative claims made. The one thing left out entirely is that any designer with reasonable ability would never do that, ever. The measurements shown are, in essence, apples to oranges. I have tried various resistor placements over the years and have found some situations where having it after was a benefit. However, it was NOT by simply sticking a resistor here or there. The crossover in toto was then fully optimized to take the resistance into account as I suspect everyone here would do. Dave, would you ever simply stick a resistor in a crossover, anywhere, without then fully optimizing the crossover, even if only the highpass?

If this type of comparison is to be made as it has, then the measurements for accurate comparison can only be relevant with "all else being equal" or as best as can be done. That is, add the resistor then optimize, otherwise you have two very different driver responses.

I don't agree that he has been treated unfairly considering his early posts such as:

I would steer clear of the Sopranos design that tweeter can sound so much better with a good crossover design.

Just guessing looking at the filter the tweeter would be struggling with the low high-pass frequency and slope made worse by the resistor "pad" without a shunt. I would be happy to prove it to you.

A comment to Jeff:

Hopefully you didn't make the same mistake for those designs, yikes...

Then as part of his proof, he makes this statement:

The truth as usual shows up in the phase response.

He also has something of a fixation on the tweeter having an Fs of 960Hz and crossing below 2K which as you know is a holdover admonition no longer relevant given the availability of crossover software. The interaction of the crossover at Fs is easily handled, one way or another. There's no consideration of the intended system usage either, in this case, a small bookshelf, not a high power stand mount. In fact, that low crossover Fc Jeff used is to be commended since as a bookshelf the listener may be quite a bit off-axis, so a low crossover Fc of a small, low power bookshelf would be highly recommended. For dispersion characteristics. By someone who takes all factors into account, that is.

He judges the sound of a system which he admits he has not heard based on his opinions about design. He has exhibited a bit of a superiority complex as well and not in just this discussion. IMO has has yet to prove his generalized contentions.

dlr

p.s. Maybe the best description of his attitude is condescension.

[Wolf]

The ratio of cap to coil is simply known as Q of the xover.
This is neither something new or something that is a rule of thumb unless you a actually calculate it. For example, LR is 0.5, and BW is 0.707, but in terms of FR, it might require a different Q to achieve the roll-off you desire. The ratio of Q is really only useful in ideal textbook situations.

Later,
Wolf

[dcibel]

It could also have something to do with transient behavior I haven't looked at the scope yet.
You talk about cap/coil ratios around here and you are greeted with the dull lifeless eyes
of a mannequin.

To be fair, you haven't actually spoke about cap/coil ratios, just some trash talk about all the projects here that have it all wrong. So we've still no idea what you're on about. Personally, with my years of electronics experience, you could say I know a thing or 2 about caps and coils. Maybe you have some magic method to making the perfect speaker, but we'll never know, it seems you are content to spit in people's faces and then expect them to ask you for advice. I suppose my dull lifeless mannequin eyes aught to be moving on for the 3rd or 4th time now... to listen to my awful distortion ridden speakers ;)

[hongrn]

Looking at all the vitriolic comments lobbed at this forum by this guy, we can safely come to a few conclusions: 1) His crossovers are done using online calculators. 2) He has no idea how a to gate an impulse response measurement. I'd disregard all his driver measurements, distortion plots, and anything related to speaker building. Go learn the basics first before spewing nonsense here.

[dlr]

He has no idea how a to gate an impulse response measurement. I'd disregard all his driver measurements, distortion plots, and anything related to speaker building. Go learn the basics first before spewing nonsense here.

The screen capture he posted of the measurement system has settings, Shape: "Rectangular" "Auto Window". It's essentially a time slice with no window setting to prevent FFT irregularities due to no tapering of the window and the start/stop times are left to the system to select if I read that correctly. I would suggest that two successive measurements with no changes whatsoever may result in two significantly different distortion plots. SPL results even with a proper tapered window will have variation, especially near the low end due to insufficient impulse length.

I have to say again that what I see does not give me confidence in the reliability of the distortion test results, separate from the other arguments made.

dlr

[dcibel]

As you can see the third harmonic is higher at 3K (the most sensitive area of our hearing)
with the resistor only the B&K mic has low enough distortion to see that. If you look
at the Via wave you can see the how low I like the 3rd harmonic. The test conditions should not have
anyone concerned about reflections. The other 2 mics are the UMM-6 and the
USB OMNI.



Maybe you guys measure speakers for different reasons than I do.
Although looking at it again the third harmonic is so low I don't think it's an issue.
I will return to this test at another date in the mean time think for yourselves and please don't drink the kool-aid.

Yeah I don't like kool-aid either - only the finest snake squeezin's for this guy!

Looks like you have a problem around 1kHz without the resistor, that pesky Fs poking through again haha ;)

3rd harmonic higher at 3kHz? We must be looking at different charts. One thing is clear, and the point that you've poorly made noting "resistor distortion" is that if you normalize the amplitude through the rest of the pass band, the tweeter with the resistor will play louder at 3kHz due to the change in transfer function it imposes. Distortion vs amplitude remains unchanged, unfortunately your measurements have not convinced me otherwise. We however already knew that and had it sorted pages back in this thread, the issue was blaming the resistor for distortion, which is doesn't inject to the circuit, it only changes the transfer function which we of course expect and intend it to do. You tried it and didn't like it - that's fine but let's not write off the resistor, follow some sort of scientific method to prove correlation and not make assumptions based on coincidence. Maybe you have had problems with Fs in the past due to non-ferrofluid tweeter with high Q resonance where the filter crossover couldn't compensate for - this will of course be represented in the transfer function and a common issue when using a calculator to determine a crossover instead of real-world data. Let's get one thing straight though - harmonic distortion caused by Fs is not a thing.

DDF makes a good point about the dispersion, if we correct for baffle diffraction at a single axis, we are likely over-compensating as the diffraction effects change a fair bit off-axis. It is important to consider a wide angle of radiation for diffraction and directivity when making design decisions, not just a single axis unless the intended installation is an anechoic chamber.

So we can look at the crossover design another way - what if we increase the crossover frequency to 4kHz+ to avoid all this pesky distortion stressing the tweeter? Well there are cons to that as well. The woofer then has to play higher in frequency where its directivity narrows (aka beaming) and we run into frequency non-linearities and is most cases distortion as the midwoofer encounters cone breakup in the high frequencies as well. It is always a trade-off, one has to make decisions based on all the data present to make the best of what we have.

[dlr]

Food for thought. I modified WinPCD to export the individual section transfer functions properly, I had the wrong complex data values prior to this, but most users probably aren't aware that the driver equalized response and circuit transfer functions can be exported to file. I also modified WinGraph to allow data below zero, since the transfer functions export as normalized values. Now the filter transfer functions can be viewed in a single graph. I'll be putting update files at my site, but these are minor changes, so it's not necessary to get the update unless you want to export the transfer function.

Two graphs. The first one is the original comparison made without/with the 6.2 ohm resistor after the tweeter network for a second order electrical. The second one is doing the same for another filter that's third order electrical as I used in my old 3-way for years (design at my site). The results of just sticking a resistor in blindly without re-optimizing the crossover to take it into account (as one would normally do) shows quite a different result.


Second order electrical network

\
Third order electrical network


dlr

[DDF]

In fact, that low crossover Fc Jeff used is to be commended since as a bookshelf the listener may be quite a bit off-axis, so a low crossover Fc of a small, low power bookshelf would be highly recommended. For dispersion characteristics. By someone who takes all factors into account, that is.

First, thank you to the original poster for not fretting about the thread hijack!

I can't comment on the sound of the speaker so my comments here are removed from that and based only on my experiences with my designs. My experience on how to deal with blending drivers of differing dispersions has been the exact opposite. I found pushing the tweeter lower and peaking it with a high Q crossover increases the 'tweeter bloom" and makes the design sound harsh in a small lively room. I listen in this type of environment allot and have many experiments and simulations/measurements followed by years of listening to come to that conclusion. IME, its better to use a low Q on the tweeter and on the woofer and have them overlap over a greater range. This assumes small speakers, drivers closely spaced. Off axis comes out smoother, design sounds less harsh in play. in a large room with late reflections, there's much less value to that, IME. FWIW

The following might be a bit more of general interest. During the design phase of a puny (3.3L) system ("The Napoleons", I posted design at DIYAudio at one time; what's posted there isn't the final design, need to find time to get that documented) using W4-1720 & D26NC55, I simulated effect of changing resistors at the input and output of the high pass. Reason was I had the xover built externally and wanted to try some quick voicing changes using alligator clippers and shunt jumpers. The impact on response shape is shown attached, again FWIW (I found it interesting). I can't recall the baseline (these are relative curves, not absolute) but it does show the differences.

[DDF]

I can't comment on the sound of the speaker so my comments here are removed from that and based only on my experiences with my designs. My experience on how to deal with blending drivers of differing dispersions has been the exact opposite. I found pushing the tweeter lower and peaking it with a high Q crossover increases the 'tweeter bloom" and makes the design sound harsh in a small lively room. I listen in this type of environment allot and have many experiments and simulations/measurements followed by years of listening to come to that conclusion. IME, its better to use a low Q on the tweeter and on the woofer and have them overlap over a greater range. This assumes small speakers, drivers closely spaced. Off axis comes out smoother, design sounds less harsh in play. in a large room with late reflections, there's much less value to that, IME. FWIW

[ATTACH=CONFIG]n1359898[/ATTACH]

Touching on this again, above is the reason I sometimes favour the "first to third" order crossover function (basically a very overdamped third) that I've posted about numerous times. Also why I favour a slight on axis system dip near tweeter roll off knee (recall being berated here on this forum at length for that one). Exact opposite of the speaker under discussion here.

FWIW, I'm not the only one with the opinion that bump at the low end of the tweeter usually (again I haven't heard this speaker) sounds overly aggressive in that range once room contribution is factored in . George Short from North Creek etc (as I've posted quite a few times) came to the same conclusion as I about overdamped 3rds and used those and "gfiandy" over at diyaudio is a commercial loudspeaker system designer (speakers for Arcam and others) and also advocates for the on axis dip, only achievable with a soft high pass knee:

http://www.diyaudio.com/forums/multi-way/316528-diy-vs-brand-speaker-26.html#post5306291