That last line in the Harbeth link just provided...
"I've always believed that optimising a speaker in a room needs nothing more than a willingness to experiment and to listen......"
Is valid.
What has helped myself ( and others ) with the understanding of the interaction of a source and reflected surface is the applet
http://www.falstad.com/interference/
Reference the bottom:
"You can also view the interference pattern between one speaker and a wall..."
And the conceptualization provide by Bob McCarthy with his use of a phase wheel relationship. He shows how gain and loss as a function of phase shift between source and reflection ( or another source ).
"I've always believed that optimising a speaker in a room needs nothing more than a willingness to experiment and to listen......"
Is valid.
What has helped myself ( and others ) with the understanding of the interaction of a source and reflected surface is the applet
http://www.falstad.com/interference/
Reference the bottom:
"You can also view the interference pattern between one speaker and a wall..."
And the conceptualization provide by Bob McCarthy with his use of a phase wheel relationship. He shows how gain and loss as a function of phase shift between source and reflection ( or another source ).
Okay, .. I plan to experiment with stuffing this weekend or thereabouts.
What benefits / drawbacks should I expect with stuffing a tapped pipe . I'm aware of the factors for conventional transmission lines, but this is a bit different since the wave at the terminus is essentially feeding back and forth along the pipe.
Can I expect deeper bass, better control of woofer cone motion, less resonances, at the expensive of some bass efficiency ? What should I look for as I inspect the impedance curves while stuffing?
I'm probably only going to be able to experiment with stuffing the at the wider half (starting from throat) as it's much too hard to get stuffing in/out of the narrow mouth, especially since the cabinet is now braced and teh top sealed.
Listened some more to the line this morning. Threw varied music at it, .. handled most of it very well at higher than normal levels but I can still find the limits of the driver if I chose to MAX OUT the gain on the sub amplifier and turn the volume up way above what I listen to. I'll have to investigate if this is amp clipping or the plate amp has an artificial bass boost built in.
Jazz to Pop to Metal to Hip Hop to Techno, .. the tapped pipe handles it all, albeit not as efficient as a true horn sub.
What benefits / drawbacks should I expect with stuffing a tapped pipe . I'm aware of the factors for conventional transmission lines, but this is a bit different since the wave at the terminus is essentially feeding back and forth along the pipe.
Can I expect deeper bass, better control of woofer cone motion, less resonances, at the expensive of some bass efficiency ? What should I look for as I inspect the impedance curves while stuffing?
I'm probably only going to be able to experiment with stuffing the at the wider half (starting from throat) as it's much too hard to get stuffing in/out of the narrow mouth, especially since the cabinet is now braced and teh top sealed.
Listened some more to the line this morning. Threw varied music at it, .. handled most of it very well at higher than normal levels but I can still find the limits of the driver if I chose to MAX OUT the gain on the sub amplifier and turn the volume up way above what I listen to. I'll have to investigate if this is amp clipping or the plate amp has an artificial bass boost built in.
Jazz to Pop to Metal to Hip Hop to Techno, .. the tapped pipe handles it all, albeit not as efficient as a true horn sub.
I think Damping on the walls is more use full than, stuffing in a tapped horn I know the DTS 20 has some sort of Foam egg crate like stuff lining it..
I believe the Stuffing in a transmission line is for reducing the Q of the Peaks in a Transmission line.
A tapped horn done right doesn't have the same High Q resonances of a Transmission line and is very flat responding compared to a Transmission line without damping. Heavy stuffing will probably just lower total output. I don't know if it will change the High pass of the Horn or not.
It will probably increase the average excursion, at the various impedance peaks.
Some one else here probably knows better.
Antone-
I believe the Stuffing in a transmission line is for reducing the Q of the Peaks in a Transmission line.
A tapped horn done right doesn't have the same High Q resonances of a Transmission line and is very flat responding compared to a Transmission line without damping. Heavy stuffing will probably just lower total output. I don't know if it will change the High pass of the Horn or not.
It will probably increase the average excursion, at the various impedance peaks.
Some one else here probably knows better.
Antone-
(If the Mods will please allow cross-posting for reference purposes)
Please have a look at posting #12 in this thread. Specifically the sentence;
"The THSPUD is part of the "next generation" of tapped horns, that use two drivers facing opposite directions to "feed" the horn.".
I have not read this thread since about page 20. So this concept may have been covered before... Has anyone made use of this information?
It seems that this would not be an isobaric push-pull configuration. But rather an 'over and under' setup with the bottom driver facing outwards of
the mouth and the upper driver facing into the throat of the TH? Further, I believe they would be wired 'in phase'?
Thoughts please...
Please have a look at posting #12 in this thread. Specifically the sentence;
"The THSPUD is part of the "next generation" of tapped horns, that use two drivers facing opposite directions to "feed" the horn.".
I have not read this thread since about page 20. So this concept may have been covered before... Has anyone made use of this information?
It seems that this would not be an isobaric push-pull configuration. But rather an 'over and under' setup with the bottom driver facing outwards of
the mouth and the upper driver facing into the throat of the TH? Further, I believe they would be wired 'in phase'?
Thoughts please...
Hi guys!
this is my first post in this wonderful forum!
i want to show you my "little" TH project...
the driver is a heavy duty 15":
qts= 0.365
qms= 3.35
qes= 0.41
fs= 33hz
vas= 53L
xmax= 35mm
Pe= 1500w rms
have a look to the picture!
is it possible??
and this is the predicted response using akabak....
approx the same!
what do you think about it??
this is my first post in this wonderful forum!
i want to show you my "little" TH project...
the driver is a heavy duty 15":
qts= 0.365
qms= 3.35
qes= 0.41
fs= 33hz
vas= 53L
xmax= 35mm
Pe= 1500w rms
have a look to the picture!
is it possible??
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.
and this is the predicted response using akabak....
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.
approx the same!
what do you think about it??
@ Oscillate: I think Tom uses two drivers to be able to use smaller drivers and make the sub flatter, for under the couch use. Facing them in opposite directions could maybe cancel some distortions, but this is just a guess. The plot also looks like a normal TH. "Second generation" could simply mean that they target a different customer type, ie. the "couch patatoe".
@andrew_87: I would go for it. Looks nice. Dont forget to make it a heavy enclosure, the 35mm xmax sounds like alot of pressure will be generated. What driver is that?
@andrew_87: I would go for it. Looks nice. Dont forget to make it a heavy enclosure, the 35mm xmax sounds like alot of pressure will be generated. What driver is that?
As promised, here are the updated hornresp data / impedance curves that I used. Compare with the observed impedance measurements if you wish (I'm guessing the difference observed 2nd impedance peak could be because of folding anomalies)
Observed impedance plot at : http://www.diyaudio.com/forums/attachment.php?s=&postid=1664991&stamp=1227322671
Theoretical impedance plot:
Observed impedance plot at : http://www.diyaudio.com/forums/attachment.php?s=&postid=1664991&stamp=1227322671
Theoretical impedance plot:
Attachments
andrew_87 said:Hi guys!
this is my first post in this wonderful forum!
i want to show you my "little" TH project...
the driver is a heavy duty 15":
qts= 0.365
qms= 3.35
qes= 0.41
fs= 33hz
vas= 53L
xmax= 35mm
Pe= 1500w rms
have a look to the picture!
is it possible??
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.
and this is the predicted response using akabak....
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.
approx the same!
what do you think about it??
Andrew_87:
Which driver is this? I looked up the Peavey 15" Low Rider, but it came with a much lower xmax value.
Assuming you plug in power to its full rated xmax, it looks like you will get something between 125 and 130 dB output. I'm very interested in this design but need to know the driver.
Thanks!
It´s probably a dual voice coil driver with two 2-ohm vcs with a very low impedance... Try double clicking on the input voltage tag, input "1 watt" and the corresponding Re to get a more realistic look on how efficient this horn is... Keep in mind that an Impedance this low is not handled by 99% of the Pro-Amps, only a few car amps can handle this. So you might have to wire the voice coils in series
hi! the driver is a USBLASTER LOWRIDER 15" dual 2ohm whit voice coil in parallel...
in the akabak simulation i have corretly set the voltage value, but in hornresp i don't know...
but i have simulate with hornresp the same driver set in reflex box, in 4phi emission, and i have got the same spl (only 2db of difference) of WinISD...
summary:
reflex box (65L fb=34hz) = 88dB
TH 4phi= 99dB
TH 2phi= 105dB
TH 1phi= 110dB
TH 0.5phi= 115dB
frequency resp= 25hz (f3) - 100hz
wonderful
in the akabak simulation i have corretly set the voltage value, but in hornresp i don't know...
but i have simulate with hornresp the same driver set in reflex box, in 4phi emission, and i have got the same spl (only 2db of difference) of WinISD...
summary:
reflex box (65L fb=34hz) = 88dB
TH 4phi= 99dB
TH 2phi= 105dB
TH 1phi= 110dB
TH 0.5phi= 115dB
frequency resp= 25hz (f3) - 100hz
wonderful
@andrew
Driven with 1 Watt you get around 96dB/m which is not very much in the Pro-Sound World, even a simple Ported Enclosure with a single 18" driver in around 150 Liters is giving you this performance.
In order to reach 125 dB, you´d need around 1,5kW RMS (Theoretically you get around 127 dB, but you have to substract Power compression in reality). So you need tremendous amounts of Amp-Power to get above 130dB.
Keep in mind that most car-drivers are not very efficient. Their capability to cope with such high Watt-power often results in a fairly wide air-gap, so they transfer the energy to heat most oft the time (infinite baffle efficency of this driver is 0,45% ). Of course, there are exceptions. I´ve not seen the US-Blaster in Reality, I am fairly deriving some thoughs of from the TSP (BTW, where did you find these, the Website only has a few incomplete ones)
How much is the US-Blaster ?
Driven with 1 Watt you get around 96dB/m which is not very much in the Pro-Sound World, even a simple Ported Enclosure with a single 18" driver in around 150 Liters is giving you this performance.
In order to reach 125 dB, you´d need around 1,5kW RMS (Theoretically you get around 127 dB, but you have to substract Power compression in reality). So you need tremendous amounts of Amp-Power to get above 130dB.
Keep in mind that most car-drivers are not very efficient. Their capability to cope with such high Watt-power often results in a fairly wide air-gap, so they transfer the energy to heat most oft the time (infinite baffle efficency of this driver is 0,45% ). Of course, there are exceptions. I´ve not seen the US-Blaster in Reality, I am fairly deriving some thoughs of from the TSP (BTW, where did you find these, the Website only has a few incomplete ones)
How much is the US-Blaster ?
@ Sabbelbacke:
you have to consider that in prosound you are in 2phi emission condition, so the spl is near 101dB, like a punisher horn...
ok, the punisher is smaller but it can't go to 30hz...
so this sub can be use in particoular type of music (ex.: 3 6 mafia,...) where a normal sub can't gave the same impact...
the driver is super for is price: is the clone of a SPL Dyn
a link:
http://www.usblaster.com/Products/Car Audio/Subwoofers/Lowrider//USB 2001
you have to consider that in prosound you are in 2phi emission condition, so the spl is near 101dB, like a punisher horn...
ok, the punisher is smaller but it can't go to 30hz...
so this sub can be use in particoular type of music (ex.: 3 6 mafia,...) where a normal sub can't gave the same impact...
the driver is super for is price: is the clone of a SPL Dyn
a link:
http://www.usblaster.com/Products/Car Audio/Subwoofers/Lowrider//USB 2001
andrew_87 said:
of course one is in 2pi space
A sub allways is when standing on the ground (well, not quite, but since the wavelength of interest is long enough, there almost ist no directivity). That´s also the case @home.In your simulation above, you are feeding 2,83 Volts into the 0,75 Ohm Driver, which actually equals 10,68 Watts. Going with the standard and not taking Re but the DIN-Numbers into account, this is a 1 Ohm driver configured like this, so 2,83V into 1 Ohm are still 8 Watts.
If you want to know how much SPL you have at 1W/1m, you have to enter 1 Volt at the "Eg" field in hornresp. Doing this, you get a liitle more than 96dB.
True, 30 Hz is "nice to have" and very rare in Pro-Sound. There are not many applications where it´s needed, one usually takes infras for this kind of thing.
I agree, if you need it, this sub surely gives more bottom than the regular PA-Sub.
My point was the sensitivity which is much lower than assumed when taking a quick look at your sim. SPL is important in Pro-Sound and having a box this size which "only" delivers around 125dB @ 1,5kW might be a dissatvantage, considering a economic point of view.
Thanx, I found this link, too. That´s why I asked about the other data you have, since not everything is listed on this page and PDFs are not available. Of course, it´s easy to re-calculate some of the data, but it´s not easy to see if they are authentic this way. There are too many Car-Subs on the market with highly tweaked spec sheets. E.g. the enormous weight should result in quite a big Magnet resulting in a very high BL product. Looking at the specs, it´s not that big - so I assume the enormous power handling capacities result from a fairly wide air-gap. But it´s hard do tell without having more data (e.g. airgap height, vc height, type of voice coil former, etc.) There is no price (or am I blind?).the driver is super for is price: is the clone of a SPL Dyn
a link:
http://www.usblaster.com/Products/Car Audio/Subwoofers/Lowrider//USB 2001
I surely didn´t won´t to be disrespectful to your deisgn, but you asked about opinions
Being for pro-sound for many years now, I wouldn´t want to have to use this much amp-power to acheive a certain SPL. In my experience, most drivers like this tend to have a very high power-compression, so even if you would have 5kW Amping available, it woudn´t result in a linear increase of level (it never does, even the best PA-Speakers on the market have around 3dB powercompression at their rated max-level).It would be interesting to know a price for this driver. If it´s not too expensive, this surely is a nice flat response plot. But if it´s comparable to some JTS or other high-price woofers, there are alternatives (2 x 18" in a ported design or bandpass do give the same low and have much more headroom without needing several kWs).
One thing that occured to me when looking at the sim: The compression ratio is very high, around 7:1. That´s quiet a lot, putting a lot of stress on the cone. With almost 400g weight, it might be enough, but without actually putting it to the test it´s hard to tell. Almost all CAR-Subs are designed for front mounting in ported or closed enclosures where the acoustical impedance load is much "eaysier" on the cone than in a horn-design. The high mass mostly serves the purpose of lowering fs. Even the LAB-Subs which use especially designed speakers (LAB12) to put in a horn have much lower compression ratio...
Of course, putting a car-sub in a TH surely is a interesting idea. One thing I came up with a while ago while fiddeling around with numbers was this:
Which results in 50 Liter Box (it just wanted to try it out to see if it works, but never got the time. purpose was a small PA-Sub for a little Party in the basement or stuff like this). The Tang Band is similar in design to many car-speakers (actually it´s used in cars a lot)... I didn´t persue it because a little deltalite 2510 was doing a good job.. but still, I´d love to have the time to try it, a 10" car-sub I put in a TH prototype just for fun put out a lot of punch...
does somebody have one of these car-monsters in germany? maybe we give it a try?
Of course, putting a car-sub in a TH surely is a interesting idea. One thing I came up with a while ago while fiddeling around with numbers was this:
An externally hosted image should be here but it was not working when we last tested it.
Which results in 50 Liter Box (it just wanted to try it out to see if it works, but never got the time. purpose was a small PA-Sub for a little Party in the basement or stuff like this). The Tang Band is similar in design to many car-speakers (actually it´s used in cars a lot)... I didn´t persue it because a little deltalite 2510 was doing a good job.. but still, I´d love to have the time to try it, a 10" car-sub I put in a TH prototype just for fun put out a lot of punch...
does somebody have one of these car-monsters in germany? maybe we give it a try?
first: thank you to teach to me how set the voltage value in horn resp!
also in my opinion the initial spl performance was too high for this kind of driver...
thanks for your opinion!
to calculate the true spl i have set the EG = sqrt( Re ) = 0.866V getting 95dB exately the same spl using akabak! OK, that's right!
i'm according to you... in PA dB are our friends!
in my opinion to get the most SPL in tapped horn we have to use driver similar to the ideal horn driver: low qes, high fs (or not?) AND high Xmax...
what do you thing?
the sub is really good, in my opinion, for high low frequency output, sincerally i don't know if the t&s are correct...
but the performance/cost quotient is really high! thanks to a friend i can get this sub for less than 250€
i'm very happy to discuss with good and very clever person!
my project was an experiment... I don't know if I really create this sub... probably for extreme car audio is good, but for PA is too big and the real SPL is too low...
also in my opinion the initial spl performance was too high for this kind of driver...
thanks for your opinion!
Sabbelbacke said:
of course one is in 2pi space
In your simulation above, you are feeding 2,83 Volts into the 0,75 Ohm Driver, which actually equals 10,68 Watts. Going with the standard and not taking Re but the DIN-Numbers into account, this is a 1 Ohm driver configured like this, so 2,83V into 1 Ohm are still 8 Watts.
If you want to know how much SPL you have at 1W/1m, you have to enter 1 Volt at the "Eg" field in hornresp. Doing this, you get a liitle more than 96dB.
to calculate the true spl i have set the EG = sqrt( Re ) = 0.866V getting 95dB exately the same spl using akabak! OK, that's right!
Sabbelbacke said:
i'm according to you... in PA dB are our friends!
in my opinion to get the most SPL in tapped horn we have to use driver similar to the ideal horn driver: low qes, high fs (or not?) AND high Xmax...
what do you thing?
Sabbelbacke said:
the sub is really good, in my opinion, for high low frequency output, sincerally i don't know if the t&s are correct...
but the performance/cost quotient is really high! thanks to a friend i can get this sub for less than 250€
Sabbelbacke said:
I surely didn´t won´t to be disrespectful to your deisgn, but you asked about opinions
i'm very happy to discuss with good and very clever person!
my project was an experiment... I don't know if I really create this sub... probably for extreme car audio is good, but for PA is too big and the real SPL is too low...