Legis,
I don't know if that foam is needed if you low pass the PPTP sub. As there is a big exposed direct radiator even with the foam in place, all it would really do is maybe reduce the first direct reflection induced peak/dip which I think will be in the 500Hz range (above your low pass) anyway. Also, it really detracts from the looks of your sub 🙁 are you saying there is an echo without it? That may just be the time delayed output of the sub due to the 3 meter time of flight. Stuffing in the space between the driver cones may help this. Just add loose fluffy polyfill there - it won't harm driver cones. Check the impulse response with and without foam to see if you have the echo or if it gets attenuated.
I don't know if that foam is needed if you low pass the PPTP sub. As there is a big exposed direct radiator even with the foam in place, all it would really do is maybe reduce the first direct reflection induced peak/dip which I think will be in the 500Hz range (above your low pass) anyway. Also, it really detracts from the looks of your sub 🙁 are you saying there is an echo without it? That may just be the time delayed output of the sub due to the 3 meter time of flight. Stuffing in the space between the driver cones may help this. Just add loose fluffy polyfill there - it won't harm driver cones. Check the impulse response with and without foam to see if you have the echo or if it gets attenuated.
Yes look-wise it's quite hopeless 😀.
I think it can relate to the synergy-originating sound waves that get inside the TH and "echo" there. The TH is collecting surrounding sounds like a microphone to some extent, like all horns. Or perhaps it's the same effect than with adjacent rooms, ie. I get delayed sound from kitchen and corridor. TH could be understood as a small room perhaps?
I have to test some more. My first reaction was I liked them immediately. Also the low passed sound (when listening to THs solo) was slightly smoother/mellower sounding with the dampers.
Some progress, put the top plate permanently on the first TH, some terminals from CMC and some preliminary painting (easier to do while the top is still open). Outside color is still undecided.
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The white paint looks great. I would go for all white Duratex on outside. I have a horn done this way and it works and looks great in home setting. Black is too much for a large box like this. Surprised you didn't put the speaker terminals on back of sub but in the mouth. Easy to access compared to back. I remember when Google revolutionized rack mount server farms by putting all cable connectors on the front where they are easy to access. Who needs a fancy panel and have it be a pain to service or change out connections?
That is an option too, all white... Where to get this stuff in EU, anybody know? Blue Aran seems to sell some their own brand Tuff Cab texture paint for speaker cabinets. RAL 3002 Red (textured) outer side and white (smooth) inner side to both TH's and synergy horn, could look very cool. 🙂
Tuff Cab Speaker Cabinet Paint - RAL 3002 Carmine Red 5Kg NEW!! Tuff Cab Pro - new formulation
I had to think the terminal placement quite much. This time the requirement was 1) easy access to both sides of the terminals for future service (rules out back plate) and 2) terminals should not be sticking out of any side because the box has sometimes to be rolled on it's side or back when mounting/unmounting the heavy-ish drivers. That location was s small revelation when it occured to me, lol 🙂.
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Legis,
The Tuffcab sounds like the same thing as Duratex as it is viscous textured stuff that applies with a roller. I like your white inside and over the top carmine red exterior. As long as the wife is happy 😀
I forgot you need to roll your cabinet - but that is why they make recessed pocket "pro touring style" terminal cups. I roll mine too when making adjustment or sometimes to move them a short distance on carpet. Your inside the mouth mount for the posts is a great idea and makes it cool looking. If it were up to me, all amps should have terminal post front mounted like a lab bench power supply. We certainly connect/disconnect them frequently enough as diyer's.
The Tuffcab sounds like the same thing as Duratex as it is viscous textured stuff that applies with a roller. I like your white inside and over the top carmine red exterior. As long as the wife is happy 😀
I forgot you need to roll your cabinet - but that is why they make recessed pocket "pro touring style" terminal cups. I roll mine too when making adjustment or sometimes to move them a short distance on carpet. Your inside the mouth mount for the posts is a great idea and makes it cool looking. If it were up to me, all amps should have terminal post front mounted like a lab bench power supply. We certainly connect/disconnect them frequently enough as diyer's.
Does PPSL loading change some things regarding the sims vs. real impedance measurements?
Here's the measured impedance of the first TH with the top plate fully attached: (They are quite sensitive mics, even soft hand clapping generate enough voltage/current so that the signal indicator leds light on my external sound card. The small variations in the plot might be due to some mic action.)
And here is a sim with 300cm path lenght that placed the middle and upper resonance peaks to quite at the same frequency as the measured ones:
Except that the measured impedance peak are much less spikier than simmed:
Lowest spike:
sim: 12,7Hz/54ohm
measured: 13,9Hz/24,6ohm
Middle:
sim: 47,5Hz/19,5ohm
measured: 43,7Hz/12,3ohm
Upper:
sim: 101,4Hz/12ohm
measured: 103,8Hz/7,12ohm
What gives? Does the push-pull slot loading reduce impedance peaking by quite a margin?
Here's the measured impedance of the first TH with the top plate fully attached: (They are quite sensitive mics, even soft hand clapping generate enough voltage/current so that the signal indicator leds light on my external sound card. The small variations in the plot might be due to some mic action.)
An externally hosted image should be here but it was not working when we last tested it.
And here is a sim with 300cm path lenght that placed the middle and upper resonance peaks to quite at the same frequency as the measured ones:
An externally hosted image should be here but it was not working when we last tested it.
Except that the measured impedance peak are much less spikier than simmed:
Lowest spike:
sim: 12,7Hz/54ohm
measured: 13,9Hz/24,6ohm
Middle:
sim: 47,5Hz/19,5ohm
measured: 43,7Hz/12,3ohm
Upper:
sim: 101,4Hz/12ohm
measured: 103,8Hz/7,12ohm
What gives? Does the push-pull slot loading reduce impedance peaking by quite a margin?
Nice agreement with sims! The difference in impedance amplitude is normal - the simulations don't account for losses due to damping or wall flex of the cabinets that de-Q the system. Be careful with your soundcard - the drivers are indeed sensitive mics and can easily generate a signal that has enough voltage to blow your input op amp. I did this on mine right after I finished the measurement on a 100dB sensitive horn - the mic generated signal killed my sound card inputs. 🙁
In retrospect I will use clamping Zener diodes the next time set at 5v to prevent demise of future soundcards.
In retrospect I will use clamping Zener diodes the next time set at 5v to prevent demise of future soundcards.
Some preliminary throat transition smoothing done with wood filler. Will do the rest of the smoothing when I finish the horns in next few weeks.
Some near field square waves (100Hz and 400Hz) 😉.
I will try to measure the possible midwoofer/comp modulation tomorrow with some dual tone IMD measurements. I have not seen anyone touch this question... Based on listening I don't suspect there to be much modulation at "human levels", but we'll see.
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Some near field square waves (100Hz and 400Hz) 😉.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I will try to measure the possible midwoofer/comp modulation tomorrow with some dual tone IMD measurements. I have not seen anyone touch this question... Based on listening I don't suspect there to be much modulation at "human levels", but we'll see.
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Legis,
Square waves look fairly square, what did you end up with for the TH/15 Xover settings?
The modulation results should be interesting, hope to see the 2446 response with the 15"s pumping and then with them shorted.
Also, it would be interesting to see the 2446 run through some of the tests performed in this thread for comparison:
http://www.diyaudio.com/forums/multi-way/212240-high-frequency-compression-driver-evaluation.html
Your horn is different (obviously) but the Maltese horn i used is also a conical expansion.
Art
It's right now at 70Hz/LR4 (15 inchers without xo). They integrate very good at the listening position with 7ms/7.6ms/9ms delay on the 15"/2"/supertweeter respectively. Those measurements were solo synergy without the super tweeters and TH's, measured at the mouth of the horn.
I would not presume that modulation causes that much FR changes/linear distortion, but intermodulation distortion (IMD) like with all coaxial drivers.
Here are some preliminary measurements. Measurements were done at the mouth of the horn at 0 deg.
15 inchers have 500hz/LR2 lowpass
Compression drivers has 500Hz/BW8 highpass (steep xo to eliminate "natural IMD")
The freq response of the channels:
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Base level of the measurement system:
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180Hz (f1) and 900Hz (f2) dual tone measurement (signal generated with ARTA, measured with REW).
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80Hz (f1) + 900Hz (f2) dual tone measurement(signal generated with ARTA, measured with REW) :
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There are clear f2 - f1 / f2 + f1 IMD components in both plots. Other modulation components seem to be much lower in level.
Some of the IMD can be account to the mic (Behringer EMC8000) naturally, but how much at the given SPL is the question.
I will measure them later today mic taken further away from speakers and playing them louder.
Here's measurements from listening position 2,8 metres away from the horn's mouth. The SPL level is calibrated.
To see the mic's own IMD I made "reference" measurements using the left channel Deltalites and right channel 2446J. Left & right Deltalites were not level matched but near enough for my purposes.
If you wonder why the H2 of the 900Hz (= 1800Hz) in the 180&900Hz pictures are larger than in the 80Hz&900Hz pictures, it is because that the "5*f1 + f2" (= 1800Hz = H2) intermodulation component sums into the H2 content of the driver...
Eminence Deltalites are very low THD radiators in this application due to their minimized excursion, maximized sensitivity and bandpass effect of the front chamber + compression ratio. Ruling harmonic is H2 all the way (due to the air compression itself), which is around -55 ... 65dB down at >100dB levels between 100Hz and 500hz (lowest at 300-500Hz).
180Hz + 900Hz from listening position (right Deltalites + right 2446J):
180Hz + 900Hz from listening position (LEFT Deltalites + right 2446J):
80Hz + 900Hz from listening position (right Deltalites + right 2446J):
80Hz + 900Hz from listening position (LEFT Deltalites + right 2446J):
To see the mic's own IMD I made "reference" measurements using the left channel Deltalites and right channel 2446J. Left & right Deltalites were not level matched but near enough for my purposes.
If you wonder why the H2 of the 900Hz (= 1800Hz) in the 180&900Hz pictures are larger than in the 80Hz&900Hz pictures, it is because that the "5*f1 + f2" (= 1800Hz = H2) intermodulation component sums into the H2 content of the driver...
Eminence Deltalites are very low THD radiators in this application due to their minimized excursion, maximized sensitivity and bandpass effect of the front chamber + compression ratio. Ruling harmonic is H2 all the way (due to the air compression itself), which is around -55 ... 65dB down at >100dB levels between 100Hz and 500hz (lowest at 300-500Hz).
180Hz + 900Hz from listening position (right Deltalites + right 2446J):
An externally hosted image should be here but it was not working when we last tested it.
180Hz + 900Hz from listening position (LEFT Deltalites + right 2446J):
An externally hosted image should be here but it was not working when we last tested it.
80Hz + 900Hz from listening position (right Deltalites + right 2446J):
An externally hosted image should be here but it was not working when we last tested it.
80Hz + 900Hz from listening position (LEFT Deltalites + right 2446J):
An externally hosted image should be here but it was not working when we last tested it.
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Legis,
Those are great looking measurements - thanks for providing us this glimpse into your system so that we can vicariously enjoy the making of your over the top horn system. Your IMD magnitudes are low that I would not think they are of a concern. I am guessing that they may actually be from the mic itself as any transducer subjected to two tone sine will show. Your HD components are very low and indicates that this system sounds very clean and pure. I am surprised you have good output down to 55Hz. You almost don't need the PPTP sub. Is that from room modes because the sims showed roll off at 100Hz. Nice work and keep the measurements coming! 🙂
Can we get off axis data at some point?
Thanks,
X
Those are great looking measurements - thanks for providing us this glimpse into your system so that we can vicariously enjoy the making of your over the top horn system. Your IMD magnitudes are low that I would not think they are of a concern. I am guessing that they may actually be from the mic itself as any transducer subjected to two tone sine will show. Your HD components are very low and indicates that this system sounds very clean and pure. I am surprised you have good output down to 55Hz. You almost don't need the PPTP sub. Is that from room modes because the sims showed roll off at 100Hz. Nice work and keep the measurements coming! 🙂
Can we get off axis data at some point?
Thanks,
X
Thank you for your kind words! The near field measurement from horn's mouth goes lower than the room response. I don't get much output from them below ~70-80Hz from listening position and level of lows are somewhat lower in general. TH's are crossed at 70Hz/LR4 right now, Deltalites without high pass.
I will try to measure the polar responses next. I cannot "standardize" the measurement angle in any way, but maybe 3-4 steps horizontally/vertically, quite evenly spaced, is enough. 🙂
Here are the polars. I measured at 0deg, and almost at the the edge of the flares coverage, and in two evenly spaced points between them.
1) Measurement distance around 1,2m from the mouth.
Horizontal 5ms time window:
Horizontal 50ms time window:
Vertical 5ms time window:
Vertical 50ms time window:
2) Measurement distance around 20cm from mouth:
Horizontal 5ms time window:
Horizontal 50ms time window:
Vertical 5ms time window:
Vertical 50ms time window:
To ear their sounds/balance seems virtually the same at all angles of the flares coverage, except the very edge of the flare. 🙂
1) Measurement distance around 1,2m from the mouth.
Horizontal 5ms time window:
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Horizontal 50ms time window:
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Vertical 5ms time window:
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Vertical 50ms time window:
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2) Measurement distance around 20cm from mouth:
Horizontal 5ms time window:
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Horizontal 50ms time window:
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Vertical 5ms time window:
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Vertical 50ms time window:
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To ear their sounds/balance seems virtually the same at all angles of the flares coverage, except the very edge of the flare. 🙂
I had the priviledge of listening to these "minimonitors" yesterday here in Jyväskylä - thank you Legis!
The sound is unbelievable, almost sort of supernatural like the Matrix world - in a good way. Transients and the raspiness of male bass and eg. saxophone is Super. Now I can say like some others that (synergy)horns have better dynamics, obviously the heavily dominating direct sound is the key to this. Stereo image is natural, not like with headphones. The solid tile/plaster walls obviously give lots of reflections but I didn't feel like wanting room treatment.
The lowest bass from the THs was very quick and solid too. The integration of the supertweeter needs some tuning still and also xo slopes can be fine tuned with PEQ of minidsp. This will take some time and experimenting with several iterations and measurements. My impaired hearing above 6kHz prevents me from saying anything about treble quality. The rippled spl measurement is typical to large horns and varies with different microphone positioning - no need for equalizing it.
The size of speakers is HUGE, congratulations Legis for having such a tolerant girlfriend!
The sound is unbelievable, almost sort of supernatural like the Matrix world - in a good way. Transients and the raspiness of male bass and eg. saxophone is Super. Now I can say like some others that (synergy)horns have better dynamics, obviously the heavily dominating direct sound is the key to this. Stereo image is natural, not like with headphones. The solid tile/plaster walls obviously give lots of reflections but I didn't feel like wanting room treatment.
The lowest bass from the THs was very quick and solid too. The integration of the supertweeter needs some tuning still and also xo slopes can be fine tuned with PEQ of minidsp. This will take some time and experimenting with several iterations and measurements. My impaired hearing above 6kHz prevents me from saying anything about treble quality. The rippled spl measurement is typical to large horns and varies with different microphone positioning - no need for equalizing it.
The size of speakers is HUGE, congratulations Legis for having such a tolerant girlfriend!
Legis,
The polars look excellent and your listening impression that they are very even over the included angle of the horns is backed up by the measurement. Well done!
@Juhazi,
Thank you for sharing your impressions of these massive speakers. I will have to vicariously experience these beauties through your notes here until Legis uploads some real high quality recordings of sound clips with a proper XY mic recorder.
Minimonitors! LOL
The polars look excellent and your listening impression that they are very even over the included angle of the horns is backed up by the measurement. Well done!
@Juhazi,
Thank you for sharing your impressions of these massive speakers. I will have to vicariously experience these beauties through your notes here until Legis uploads some real high quality recordings of sound clips with a proper XY mic recorder.
Minimonitors! LOL
Thanks CLS (I have much time!), and thanks Juhazi for the visit! You are most welcome to come and hear them again after they have gotten some paint and finishing touches on them.
Vertical polar plot seems almost perfect to me. If it were done as a sonogram, it would show very smooth and wide bandwidth constant directivity.
Horizontal plane shows some anomalies between 2khz and 8khz. The throat transition is much better vertically than horizontally and I hope the horizontal polars also get smoother once the throat has been smoothened properly. Right now it's very crude, has not even seen a sanding paper yet 😀. After 5-10 cycles of sanding-reapplying wood putty it will have a curved and smooth transition. 🙂
edit. Regarding Juhazi's listening comments, I totally agree with them. The resolution is simply amazing at 0,4-0,5ms long room echo. I like the speed, clarity and that what horns do best, ie. the "snappiness" of the sounds. PP-THs have special sound also, I'm very fond of them. After thinking that everything in bass department is heard in a form or another, they keep on delighting me every time I switch them on. 🙂
Vertical polar plot seems almost perfect to me. If it were done as a sonogram, it would show very smooth and wide bandwidth constant directivity.
Horizontal plane shows some anomalies between 2khz and 8khz. The throat transition is much better vertically than horizontally and I hope the horizontal polars also get smoother once the throat has been smoothened properly. Right now it's very crude, has not even seen a sanding paper yet 😀. After 5-10 cycles of sanding-reapplying wood putty it will have a curved and smooth transition. 🙂
edit. Regarding Juhazi's listening comments, I totally agree with them. The resolution is simply amazing at 0,4-0,5ms long room echo. I like the speed, clarity and that what horns do best, ie. the "snappiness" of the sounds. PP-THs have special sound also, I'm very fond of them. After thinking that everything in bass department is heard in a form or another, they keep on delighting me every time I switch them on. 🙂
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By the way, regarding the PP-TH/TP, it also seems to be quite allrounder what comes to different drivers. For example Eminence Sigma Pro 18A simmed very good in it, but it's totally different type of a driver than 18N860 (simmed actually slightly better than 18N860). I think the long-ish pipe section loads the driver uniformly/frequency independent way and keeps it from resonating (that prevents saddle effect and it's resulting GD spike and also attenuates the HF resonances in the sims).
I did some impedance measurements of the synergy horn in it's current state.
2446J's impedance in synergy:
Dual parallel Deltalite 2515's in synergy:
Deltalites seems to have very small impedance variation, almost like the impedance of a damped TL and such. Quite a non-reactive load and good for tube amps. 60Hz system resonance is quite low for 30litre back chamber, what did the simulation say about the system resonance's frequecy, X? I quess the used damping material is quite effective?
2446J's HF impedance ripple is mainly or at least partly because the original ribbed titanium 'phragm is not the best option out there. Truextent beryllium diaphragms will be my next investment at some point. They do not have diaphragm resonances until ~22kHz and do not have such ragged impedance response below 20Khz.
I did some impedance measurements of the synergy horn in it's current state.
2446J's impedance in synergy:
An externally hosted image should be here but it was not working when we last tested it.
Dual parallel Deltalite 2515's in synergy:
An externally hosted image should be here but it was not working when we last tested it.
Deltalites seems to have very small impedance variation, almost like the impedance of a damped TL and such. Quite a non-reactive load and good for tube amps. 60Hz system resonance is quite low for 30litre back chamber, what did the simulation say about the system resonance's frequecy, X? I quess the used damping material is quite effective?
2446J's HF impedance ripple is mainly or at least partly because the original ribbed titanium 'phragm is not the best option out there. Truextent beryllium diaphragms will be my next investment at some point. They do not have diaphragm resonances until ~22kHz and do not have such ragged impedance response below 20Khz.
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