Vifa DX25TGO5 and wave guide?
Hi John,
I would like to find a good inexpensive dome tweeter that is reasonably efficient. I would like to use them with some Stephens Trusonic 80FR 8"drivers crossed over around 3.5kHz. Your wave guide idea looks worth the effort to try.
I found a Vifa DX25TGO5 that may work out with this 95db efficient fullrange driver.
Have you experiemented with any of the Vifa tweeters and your waveguide? And do you feel the DX25 tweeter would be a good choice with your wave guide implimented?
Thanks
Norris Wilson
Hi John,
I would like to find a good inexpensive dome tweeter that is reasonably efficient. I would like to use them with some Stephens Trusonic 80FR 8"drivers crossed over around 3.5kHz. Your wave guide idea looks worth the effort to try.
I found a Vifa DX25TGO5 that may work out with this 95db efficient fullrange driver.
Have you experiemented with any of the Vifa tweeters and your waveguide? And do you feel the DX25 tweeter would be a good choice with your wave guide implimented?
Thanks
Norris Wilson
I'll have to try this myself, looks very promising!
JonPike said:
Greets!
At a glance I couldn't see/find enough details to form an opinion, but when loading diaphragms that are easily deformed you rapidly reach a point of diminishing returns between lowering Fc and increasing distortion to an unacceptable level, which of course is listener dependent. I'm not familiar with current tweeters, but FWIW I did fairly extensive experimentation decades ago using cheap RadioShack 1" silk domes and found it could be conically loaded at up to a 2:1 CR @ 0.707*Fs @ >60 deg.. The WG was so big though that all things considered, the ~10x higher cost (at the time anyway) for a 1" exit high SQ aluminum diaphragm compression driver was worth it.
I did find them worth the effort for physically aligning the drivers at the XO point (improving their power response a bit as a side benefit) though, and have periodically suggested doing this on various audio mailing lists/forums, but it's only been since manufacturers recently resorted to this for multi-channel music/movie mastering that it's become the 'Hot Ticket'.
That said, the detractors at the time said we can't hear the minor timing error of offset drivers with the 2-3 kHz XOs of today's typical two/three way designs. I don't know since I've never tried it, but it's plenty audible to me at up to 1.2 kHz, so as always YMMV.
GM
Norris,
the DX25 would be a good candidate for a WG. It already has robust performance in the low end and excellent dispersion. The WG would lower distortion and/or allow for an even low XO point (already low for a "1 inch" dome). The controlled directivity in this range also allows superior matching to the off axis performance of the chosen midbass driver.
Which brings us to the 8" fullrange driver (I know nothing of the specifics of that driver, but this is largely irrelevant). It should be beaming badly at 3.5k. Even if it isn't, the whole point of the WG would be lost, excepy maybe a bit of directional control and time alignment. Also, it functions as a low gain horn. It will have zero effect on the efficiency above loading.
But of course, don't let me stop you from doing it if that is your desire
.Cheers,
AJ
p.s. please, please, not to discourage anyone, but a WG loaded tweeter or a dipole, etc, should be your 20th speaker project, not your 3rd - or 1st. But then again, what would I know
? An externally hosted image should be here but it was not working when we last tested it.
Thanks AJ for your reply.
Unfortunetly I do not have any measurements of the Trusonic 8" fullrange drivers, nor do I have a way to obtain them.
I am not sure about where these drivers start to beam. But, I hope since they lack a wizzer cone, that it may be a little higher than the average 8" fullrange.
I would like to find an affordable driver that is efficient enough to run on 2watts. A driver that will play well from 80Hz to 3kHz or so without a crossover.
Does anyone have a quality high efficiency driver that they would recommend for this application?
I have to agree with you about not trying to build a dipole speaker on your 1st or 3rd project. But, I feel the waveguide should be possible.
I assume the dipole speaker in your picture, is an Orion by Linkwitz.
The Orion would be an ambitious project indeed. Especially since it requires a few thousand dollars investment, and a mass amount of equalization and 8 channels of amplification.
Since I am biased towards vacuum tube amplifiers. I would not try to build an Orion speaker system due to the huge pile of equipment needed to run them, not to include the room heating of the vacuum tubes.
I would think in order to keep the sound character of vacuum tubes, one would need at least a total of 4 channels of tube amplifiers for the midrange and treble drivers.
The Orion has to be one of the finest speakers around based on the dipolar principles and it being fully active, no box colorations.
But I have not had the oportunity to listen to a pair.
Any comments about these speakers for those who have not heard them?
Norris Wilson
Unfortunetly I do not have any measurements of the Trusonic 8" fullrange drivers, nor do I have a way to obtain them.
I am not sure about where these drivers start to beam. But, I hope since they lack a wizzer cone, that it may be a little higher than the average 8" fullrange.
I would like to find an affordable driver that is efficient enough to run on 2watts. A driver that will play well from 80Hz to 3kHz or so without a crossover.
Does anyone have a quality high efficiency driver that they would recommend for this application?
I have to agree with you about not trying to build a dipole speaker on your 1st or 3rd project. But, I feel the waveguide should be possible.
I assume the dipole speaker in your picture, is an Orion by Linkwitz.
The Orion would be an ambitious project indeed. Especially since it requires a few thousand dollars investment, and a mass amount of equalization and 8 channels of amplification.
Since I am biased towards vacuum tube amplifiers. I would not try to build an Orion speaker system due to the huge pile of equipment needed to run them, not to include the room heating of the vacuum tubes.
I would think in order to keep the sound character of vacuum tubes, one would need at least a total of 4 channels of tube amplifiers for the midrange and treble drivers.
The Orion has to be one of the finest speakers around based on the dipolar principles and it being fully active, no box colorations.
But I have not had the oportunity to listen to a pair.
Any comments about these speakers for those who have not heard them?
Norris Wilson
AJinFLA said:
Greets!
In an interview very early in his career, Roger Penske was asked why he chose to start racing in a Corvette (fastest production class) rather than in the time honored way of learning the craft by progressing up through the slower classes, to which he snapped back, "I did!"
GM
Thanks GM .
Hi Norris,
the pic was not to point out a dipole, that's a WG loaded Vifa - the XT19.
Cheers,
AJ
.Hi Norris,
the pic was not to point out a dipole, that's a WG loaded Vifa - the XT19.
Cheers,
AJ
An externally hosted image should be here but it was not working when we last tested it.
Norris Wilson said:
Greets!
Assuming you want to listen to a variety of music without clipping the amp, then it must be able to handle up to at least +30 dB transient spikes. If your loudest desired average is at a ~live acoustic jazz venue, then with two watts this means ~85 dB + (30-3) dB = ~112 dB/W sens., so the horn or array would be unacceptably big/expensive. At 75 dB avg., or what many folks watch TV movies at, you still need ~102 dB/W. AFAIK, only huge compression or 'top drawer' FR driver (Lowther, AER, etc.) horns are this efficient over this wide a BW, so once you move away from these types of systems, it boils down to how much tube 'euphonic distortion' is acceptable.
GM
Hi GM,
I agree with your comments about efficiency and available drivers to do the job at realistic listening levels.
This is something that I have been trying to iron out with very little success, and still keep the speaker system simple.
I am about to the conclusion that moderate listening levels are all that I will be able to acheive with this simple fullrange system approach, 75db with peaks on 2 plus watts.
I love the dynamics and lack of distortion of a horn based speaker. But, there are to many variables to consider for my liking. Variables like equalization, huge bass cabinets, with multiple drivers and amplifiers to run such a system to achieve 20Hz to 20kHz.
One of the most enjoyable home audio listening experiences that I have had, was with a four-way horn system.
The system consisted of pair of 18" Bag end subwoofers, a double horn loaded JBL bass bin with 2 x 15" woofers, a 2" JBL mid-range compression driver on multi-cell horn, and a JBL compression tweeter with a slot wave guide.
This system was driven with over 830 watts per channel, and felt like it was rippling my skin from the sound waves at 130db, yipee.
If you have any speaker suggestions that will fill my wide frequency range, less is best, efficient and reasonably priced for DIY applications desires? I am all ears and would like to persue such a speaker.
I am not asking for much, maybe????
In life, we always have to weigh out the compromises and deside which compromises are best for us, especially if it is chasing audio.
I feel like the less is best approach has its merits, and is more realistic for my room, budget, and desire to keep the equipment pile to a reasonable minmum.
Listen to the music!
Thanks
Norris Wilson
I agree with your comments about efficiency and available drivers to do the job at realistic listening levels.
This is something that I have been trying to iron out with very little success, and still keep the speaker system simple.
I am about to the conclusion that moderate listening levels are all that I will be able to acheive with this simple fullrange system approach, 75db with peaks on 2 plus watts.
I love the dynamics and lack of distortion of a horn based speaker. But, there are to many variables to consider for my liking. Variables like equalization, huge bass cabinets, with multiple drivers and amplifiers to run such a system to achieve 20Hz to 20kHz.
One of the most enjoyable home audio listening experiences that I have had, was with a four-way horn system.
The system consisted of pair of 18" Bag end subwoofers, a double horn loaded JBL bass bin with 2 x 15" woofers, a 2" JBL mid-range compression driver on multi-cell horn, and a JBL compression tweeter with a slot wave guide.
This system was driven with over 830 watts per channel, and felt like it was rippling my skin from the sound waves at 130db, yipee.
If you have any speaker suggestions that will fill my wide frequency range, less is best, efficient and reasonably priced for DIY applications desires? I am all ears and would like to persue such a speaker.
I am not asking for much, maybe????
In life, we always have to weigh out the compromises and deside which compromises are best for us, especially if it is chasing audio.
I feel like the less is best approach has its merits, and is more realistic for my room, budget, and desire to keep the equipment pile to a reasonable minmum.
Listen to the music!
Thanks
Norris Wilson
Not to derail the conversation, but I think, through some recent juggling of drivers and design tweaking, the current xover point for the sptechs is 600hz, which is in the Dr. Geddes ballpark.
Eagerly waiting to see measurements of the partsexpress waveguide lip, which I suspect will be bad. But maybe we can sand them down
Eagerly waiting to see measurements of the partsexpress waveguide lip, which I suspect will be bad. But maybe we can sand them down
ooheadsoo said:Not to derail the conversation, but I think, through some recent juggling of drivers and design tweaking, the current xover point for the sptechs is 600hz, which is in the Dr. Geddes ballpark.
Eagerly waiting to see measurements of the partsexpress waveguide lip, which I suspect will be bad. But maybe we can sand them down
What, you mean derail it back to talking about waveguide concepts?
I would think the same process that John applied to the MCM waveguide would work... i.e. saw off the metal threaded part, then mill the plastic with the homemade router jig.
Problem would be, since the PE 'guides look deeper (?) than the MCM, they might end up still very deep by the time you hit the "wide enough" diameter to match the tweeter. OTOH, would it be problematic to have the tweeter throat a lot bigger than the dome size? I'd guess it wouldn't work as well if you did that, but who knows...
The lip should be easy to do something about... Sanding? Trim rings? If you can make it, that would work.
AJinFLA said:
AJ, I've never seen a crossover frequency for your unique Orion variant... are you going lower than "normal" with that XT19?
Also good to hear a reccomend, and why, for the DX25. How does one rate tweeters for their low end performance? Strong power handling, and low Fs?
My method to this madness is to sort of duplicate Mark K's RS225/RS28 two way. It seemed that the RS28 was barely able to cross as low as he needed to. (1200 or less) The waveguide treatment would help, of course.
I'm thinking maybe a 27TDFC might be slightly more able to go that low. Any others pop into mind?
JonPike said:
Greets!
A horn (aka WG in some cases) is a bandpass alignment, so has both a low (Fl) and high pass (Fh) corner frequency with the mouth area (Sm) plus end correction and any boundary gain setting its LF corner frequency and the throat area (St) setting its HF corner frequency, ergo the larger the throat for a given driver, the lower the compression ratio (CR) and frequency the horn rolls off on the top end. So the object is to balance Sm/St/CR and acoustic (not axial) length so that Fl/Fh yields a flat response to the desired F3.
GM
thats because it varies by the week and I drink alot, so my memory isn't the greatest
.If I were at home and in front of my DCX it would probably say LR24 @ 1.32k with a steep notch just below. It's also been 48LR w/notch. I think it changed when I saw Feyz's excursion data. Or maybe it was the last time I went to happy hour. I've really lost interest in fiddling with that design any more. Keep in mind also that to flatten the axial response about 15db of attenuation was required.
Mark K and Zaph are much smarter than I, so their data will be presented in a much more DIY friendly (understandable) format.
Here's Marks DX25 test:
An externally hosted image should be here but it was not working when we last tested it.
TDFC:
An externally hosted image should be here but it was not working when we last tested it.
I give extra points to superior top end dispersion to the Vifa (a must for me ). Minus points to both for being non-metal because I consider damping to be a form of distortion also - but thats a whole other can of worms that I will not discuss.
Again, mostly because I'm not as smart as Mark, I have no fear of complexity, so yes, IMHO his 2 way screams for a WG. Good luck with your projects and merry xmax.
Cheers,
AJ
Hmmm... interesting AJ!!
Looking at the two spectra.. assuming I know what I'm looking at, that is... it would seem that though the Vifa has more high end general hash, it is a lot lower in harmonics than the Seas. Wonder which sounds worse? (guessing the harmonics are a bigger factor)
I'm also seeing the "sidebands", the near but not exactly harmonic stuff off sides of each peak, is lower with the Vifa....
Another question... what's this with Feyz' excursion tests? Where might I find out about it?
Tnx...
Jon
Looking at the two spectra.. assuming I know what I'm looking at, that is... it would seem that though the Vifa has more high end general hash, it is a lot lower in harmonics than the Seas. Wonder which sounds worse? (guessing the harmonics are a bigger factor)
I'm also seeing the "sidebands", the near but not exactly harmonic stuff off sides of each peak, is lower with the Vifa....
Another question... what's this with Feyz' excursion tests? Where might I find out about it?
Tnx...
Jon
I think AJ is referring to this, and it is not test data:JonPike said:
http://members.fortunecity.com/pirimoglu//images/HPExcursionComps.html
It is nothing special, it only displays excursion plots for a high pass filter with different slopes. What it shows is, Linkwitz-Riley 4th order is the best in terms of excursion, even better than higher order slopes. This is because it starts rolling off a lot earlier than the other higher order slope version. This also means that at the early high roll off, the woofer is also producing sound, which is taking off some of the work off of the tweeter. A Linkwitz-Riley 2nd order starts rolling off a lot earlier than 4th order version, but because excursion increases 2nd order itself with decreasing frequency, a 2nd order slope is only adequate to keep the excursion at a constant level as frequency reaches to 0Hz.
Note baffle step effect is not considered here. The other thing is this only shows excursion, not protection against power input to the tweeter.
Nemophyle asked:
The formula describing a Geddes waveguide:
From AES, Vol. 37 (preprint) Formula #23
y = SQRT(a*2 + (Tan(theta)*2)(x*2))
Use the (Tangent of theta) squared
y = radius of contour
a = throat radius (2.54 cm dome = 1.27 cm)
theta = 1/2 coverage angle (for desired dispersion of 60 degrees, this is 30 degrees)
x = distance from throat
(x*2) means (x squared)
The formula describing a Geddes waveguide:
From AES, Vol. 37 (preprint) Formula #23
y = SQRT(a*2 + (Tan(theta)*2)(x*2))
Use the (Tangent of theta) squared
y = radius of contour
a = throat radius (2.54 cm dome = 1.27 cm)
theta = 1/2 coverage angle (for desired dispersion of 60 degrees, this is 30 degrees)
x = distance from throat
(x*2) means (x squared)
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