GM said:
Isn't anyone going to comment on this?
In my personal experience, dual reflex bandpass is very VERY hard to get correct. And the tapped horn has a lot in common with dual reflex bandpass. Subjectively I've found that dual-reflex designs sound 'sluggish' and 'out-of-step' with the mains. Whereas a single reflex design can be integrated without much fuss, as long as the levels, the response curve, and the timing is fairly accurate.
Has anyone heard a lab horn AND a tapped horn? Is a lab horn more 'musical?'
Both a dual reflex bandpass and a tapped horn utilize the rear wave to augment the overall response. A front loaded horn, like the lab horn, does not.
A transmission line uses the rear wave to augment the front wave, but the rear wave is significantly damped. So it's contribution to the overall response is much less dramatic.
In a tapped horn, it appears that the rear wave is just as prominent as the front wave, which is why the efficiency is so high.
A transmission line uses the rear wave to augment the front wave, but the rear wave is significantly damped. So it's contribution to the overall response is much less dramatic.
In a tapped horn, it appears that the rear wave is just as prominent as the front wave, which is why the efficiency is so high.
Patrick, it does concern me a little that GM wasn't impressed with the SQ, but not being there or seeing the setup and the source material, it's hard to make a secondhand judgement. What concerns me more is that there is a dip on the midbass that seems unavoidable, although Danley seems to have pulled it off.
Could it be that there is some special trick to do it that William didn't find? Or could it be some unobtainium driver?!
GM, wow!
40kw x 40 drivers and 105 db @ 250m!
I wonder what they actually use it for!
One thing I've noticed is that the midbass dip actually moves higher as you reduce the length. One possibility would be to make two tapped horns of different tunings and attempt to get them to further balance out the other dips. I wonder if this could work.
Another idea - what if a second driver was used and placed higher up - it would be like a second tapped horn tuned higher.
William did you try anything like this and do you think it could prove an answer?
Ideally I'd like to get this thing to be useable up to 80 Hz.
Ok so here's the idea:
We have a 1.8m and a 2.4m tapped horn - this is what it looks like:
Notice that the upper bass dips are pretty well cancelled.
Could it be that there is some special trick to do it that William didn't find? Or could it be some unobtainium driver?!
GM, wow!
40kw x 40 drivers and 105 db @ 250m!
I wonder what they actually use it for!
One thing I've noticed is that the midbass dip actually moves higher as you reduce the length. One possibility would be to make two tapped horns of different tunings and attempt to get them to further balance out the other dips. I wonder if this could work.
Another idea - what if a second driver was used and placed higher up - it would be like a second tapped horn tuned higher.
William did you try anything like this and do you think it could prove an answer?
Ideally I'd like to get this thing to be useable up to 80 Hz.
Ok so here's the idea:
We have a 1.8m and a 2.4m tapped horn - this is what it looks like:
Notice that the upper bass dips are pretty well cancelled.
Weighing it up
> it does concern me a little that GM wasn't impressed with the SQ
That was the opposite to WC’s more extensive experience . .
> I'd like to get this thing to be useable up to 80 Hz.
Me too originally, not rally now; what are you likely to want to integrate it with, that 15 Hz is significant?
OTOH, it was suggested to me that
“as there is no damping material, I would expect midrange sound waves from the back of the cone to reflect back from the untreated and parallel surface of the box onto the cone and be heard at the front of the cone.
At high volume levels one might experience standing waves.
Also, the driver being buried, as it were, inside the box would give rise to a beaming effect as the frequencies increase.”
Operating below 100 Hz, I think these are both non-issues, anyone think they are?
Cheers
> it does concern me a little that GM wasn't impressed with the SQ
That was the opposite to WC’s more extensive experience . .
> I'd like to get this thing to be useable up to 80 Hz.
Me too originally, not rally now; what are you likely to want to integrate it with, that 15 Hz is significant?
OTOH, it was suggested to me that
“as there is no damping material, I would expect midrange sound waves from the back of the cone to reflect back from the untreated and parallel surface of the box onto the cone and be heard at the front of the cone.
At high volume levels one might experience standing waves.
Also, the driver being buried, as it were, inside the box would give rise to a beaming effect as the frequencies increase.”
Operating below 100 Hz, I think these are both non-issues, anyone think they are?
Cheers
G'day Paul
>Another idea - what if a second driver was used and placed higher up - it would be like a second tapped horn tuned higher.
>William did you try anything like this and do you think it could prove an answer?
We tried this with two drivers in the 30 Hz horn, and it didn't help. Here's a picture of one of the spaced driver test boxes, in the other the top driver was 1/2 way up the line. I'll have to look for the plots. They were nothing special.
Cheers
William Cowan
>Another idea - what if a second driver was used and placed higher up - it would be like a second tapped horn tuned higher.
>William did you try anything like this and do you think it could prove an answer?
We tried this with two drivers in the 30 Hz horn, and it didn't help. Here's a picture of one of the spaced driver test boxes, in the other the top driver was 1/2 way up the line. I'll have to look for the plots. They were nothing special.
Cheers
William Cowan
Attachments
Oops, here's the pic properly linked:
Beaming?!!!!!!!
This is a subwoofer! Now if we could get more directivity in its bandwidth, that could in fact be an advantage rather than a problem. Of course, dipole is the only way this is going to happen.
The other issue is also irrelevant to a subwoofer. This would be no different to any other subwoofer. Sound inside any box speaker will get out through the cone. In most speakers this is undesirable. In this one, the sound getting through the cone is a much lesser proportion. We are talking about a subwoofer here, which makes it pretty much irrelevant anyway.
I don't think there is a lot of similarity with an 6th or 8th order bandpass. Tuning is based on line length like a TL, hence it should not be difficult to get the right tuning. I believe it isn't finicky in that way.
Some argue that undersized horns behave like bandpass more so than true horns. Still, from a design point of view I think a tapped horn is very different.
I'd also like to know if anyone has ...
The damping is to tame the resonances and TLs are normally used for midrange as well. This damping should not reduce bass output unless overdone. As I recall from playing around with Martin Kings simulations, if the density isn't too high, the resonances will be damped without reducing bass reinforcement from the line.
I believe it also allows it to behave as a true horn with a much smaller size by operating as a 1/2 wave horn one octave higher than its 1/4 wave operation which determines low frequency extension and output.
I think the reason for the upper/mid bass dip is the same reason you get this problem with a BLH. I wonder if I should actually be modelling these as a BLH instead.
William ....
Damn, it didn't work!!!!!
Ok but could that be because of two drivers in one box creating other problems? I'm curious what would happen if you were driving the offset driver with the bigger tapped horn both measured at the same time. My chart does suggest that if the tuning is different enough that the other peaks and dips should cancel.
One more thought. In the Danley version, does anyone know how the driver is actually mounted? It has an access panel in the middle - could it be that the driver is actually in there? It would seem a strange thing to do ... or does that panel serve another function?
Beaming?!!!!!!!
This is a subwoofer! Now if we could get more directivity in its bandwidth, that could in fact be an advantage rather than a problem. Of course, dipole is the only way this is going to happen.
The other issue is also irrelevant to a subwoofer. This would be no different to any other subwoofer. Sound inside any box speaker will get out through the cone. In most speakers this is undesirable. In this one, the sound getting through the cone is a much lesser proportion. We are talking about a subwoofer here, which makes it pretty much irrelevant anyway.
I don't think there is a lot of similarity with an 6th or 8th order bandpass. Tuning is based on line length like a TL, hence it should not be difficult to get the right tuning. I believe it isn't finicky in that way.
Some argue that undersized horns behave like bandpass more so than true horns. Still, from a design point of view I think a tapped horn is very different.
I'd also like to know if anyone has ...
The damping is to tame the resonances and TLs are normally used for midrange as well. This damping should not reduce bass output unless overdone. As I recall from playing around with Martin Kings simulations, if the density isn't too high, the resonances will be damped without reducing bass reinforcement from the line.
I believe it also allows it to behave as a true horn with a much smaller size by operating as a 1/2 wave horn one octave higher than its 1/4 wave operation which determines low frequency extension and output.
I think the reason for the upper/mid bass dip is the same reason you get this problem with a BLH. I wonder if I should actually be modelling these as a BLH instead.
William ....
Damn, it didn't work!!!!!
Ok but could that be because of two drivers in one box creating other problems? I'm curious what would happen if you were driving the offset driver with the bigger tapped horn both measured at the same time. My chart does suggest that if the tuning is different enough that the other peaks and dips should cancel.
One more thought. In the Danley version, does anyone know how the driver is actually mounted? It has an access panel in the middle - could it be that the driver is actually in there? It would seem a strange thing to do ... or does that panel serve another function?
paulspencer said:
Greets!
Right, this is the pipe's acoustic 3rd harmonic, so as the acoustic path-length is shortened, the dip must rise in frequency and if I understand TD's white paper correctly, it's what gets filled in by the driver's anti-phase output, putting the first major dip at the 5th harmonic somewhere above a sub's passband.
GM
Originally posted by paul
One thing I've noticed is that the midbass dip actually moves higher as you reduce the length.
Originally posted by GM
as the acoustic path-length is shortened, the dip must rise in frequency and if I understand TD's white paper correctly, it's what gets filled in by the driver's anti-phase output, putting the first major dip at the 5th harmonic somewhere above a sub's passband.
So the trade-off is upper vs lower cutoff?
GM
IIRC you said the ToP is effectively a 6th order BP.
Would you also sat that with Patrick’s view that it’s *dual reflex bandpass; and that
“dual-reflex designs sound 'sluggish' and 'out-of-step' with the mains.
Whereas a single reflex design can be integrated without much fuss, as long as the levels, the response curve, and the timing is fairly accurate.”
Cheers
One thing I've noticed is that the midbass dip actually moves higher as you reduce the length.
Originally posted by GM
as the acoustic path-length is shortened, the dip must rise in frequency and if I understand TD's white paper correctly, it's what gets filled in by the driver's anti-phase output, putting the first major dip at the 5th harmonic somewhere above a sub's passband.
So the trade-off is upper vs lower cutoff?
GM
IIRC you said the ToP is effectively a 6th order BP.
Would you also sat that with Patrick’s view that it’s *dual reflex bandpass; and that
“dual-reflex designs sound 'sluggish' and 'out-of-step' with the mains.
Whereas a single reflex design can be integrated without much fuss, as long as the levels, the response curve, and the timing is fairly accurate.”
Cheers
Greets!
As TD states and shows in an excursion plot sim in his Tapped Horn WP, there's actually less gain at tuning than in a BR, only the gain due to pipe loading, so yes, you're 'robbing Peter to pay Paul', but it's a good one for a prosound sound app if the TP is tuned low since they're only really interested in the ~60 Hz - up BW and particularly in the ~80 Hz - up BW. For a typical music/HT app, the TP makes no sense to me since it's going to be XO'd <80 Hz and typical high excursion drivers combined with relatively cheap mega power in simple pipe horns can damage houses at low distortion levels, not to mention these can easily be ~accurately simmed using any TL or BLH software.
WRT the TOP's SQ, as I noted, until proven otherwise, I believe it was all the other horn loaded cabs in close proximity 'singing along'. WRT PB's opinion, I've auditioned 8th order BPs (Karlson K-15) that if BW limited and combined with mids/HF compression horns (Altec 805 multi-cell/288 driver in this case) was heart attack 'fast' enough to make you believe you were standing next to a Nick Mason drum solo, so IMO it's dependent more on the design/implementation than the number of orders of resonance.
As always though, YMMV.
GM
As TD states and shows in an excursion plot sim in his Tapped Horn WP, there's actually less gain at tuning than in a BR, only the gain due to pipe loading, so yes, you're 'robbing Peter to pay Paul', but it's a good one for a prosound sound app if the TP is tuned low since they're only really interested in the ~60 Hz - up BW and particularly in the ~80 Hz - up BW. For a typical music/HT app, the TP makes no sense to me since it's going to be XO'd <80 Hz and typical high excursion drivers combined with relatively cheap mega power in simple pipe horns can damage houses at low distortion levels, not to mention these can easily be ~accurately simmed using any TL or BLH software.
WRT the TOP's SQ, as I noted, until proven otherwise, I believe it was all the other horn loaded cabs in close proximity 'singing along'. WRT PB's opinion, I've auditioned 8th order BPs (Karlson K-15) that if BW limited and combined with mids/HF compression horns (Altec 805 multi-cell/288 driver in this case) was heart attack 'fast' enough to make you believe you were standing next to a Nick Mason drum solo, so IMO it's dependent more on the design/implementation than the number of orders of resonance.
As always though, YMMV.
GM
BP/ Karlson etc
GM
Seems to me for music like Nick Mason etc, 80 - 400 Hz is most critical.
I’ve considered and dropped Onkens, am deferring bass horns till I have more time & skill, and thinking of a simple vented mid bass 15”. I have a pair of JBL 2035HPL’s with Fs 43 Hz, 7 mm Xmax, low Le of 0.25, BL of 17 etc. (I don’t seek to get to live levels, say 105-110 dB will do) ~ not Altecs, but within my budget.
Other than horns, in your opinion would a Karlson or some other rig do transients/ drums any better than a good driver in a good vented box?
Cheers
GM
Seems to me for music like Nick Mason etc, 80 - 400 Hz is most critical.
I’ve considered and dropped Onkens, am deferring bass horns till I have more time & skill, and thinking of a simple vented mid bass 15”. I have a pair of JBL 2035HPL’s with Fs 43 Hz, 7 mm Xmax, low Le of 0.25, BL of 17 etc. (I don’t seek to get to live levels, say 105-110 dB will do) ~ not Altecs, but within my budget.
Other than horns, in your opinion would a Karlson or some other rig do transients/ drums any better than a good driver in a good vented box?
Cheers
Re: BP/ Karlson etc
Greets!
Freddy and a few others don't mind XOing Ks as high as 500 Hz, but going from a near 50 yr distant memory, I do, so something like what RCA-fan calls a 1/2 horn seems a reasonable solution, though I prefer the better damped ~max flat impedance TL variant.
Got the rest of the HPL's specs?
GM
Greets!
Freddy and a few others don't mind XOing Ks as high as 500 Hz, but going from a near 50 yr distant memory, I do, so something like what RCA-fan calls a 1/2 horn seems a reasonable solution, though I prefer the better damped ~max flat impedance TL variant.
Got the rest of the HPL's specs?
GM
Hi GM
I thought a concern of all or most Ks, is a peak at c. 200 Hz, often about 2 dB. Guess it might be notched out, but maybe it’s only the peak giving an illusion of better transient response?
A constraint, and a workaround: I don't want a box bigger than about 70 L (2.5 cubic ft), *but I will use an active “sub” underneath which goes deep, crossing about 60 – 80 Hz
The tapped horn or a TL would be an alternative to the sub.
I apologize for digressing to the next ~3 octaves above what a TH can cover.
The HPL's specs are:
Fs 43
Re 4.7
Qms 4.9
Qes 0.36
Sd 880 cm2
Vas 192 L (6.8 cubic ft)
Xmax 7.0 mm (0.28”)
Le 0.25
With the low Le, I had one steam of thought that the 2035 could be used even to say 1200 Hz without too much distortion(?), avoiding the need for a mid driver. The idea of avoiding a mid driver is one less crossover, less induction losses, and allow a sweet low powered amp (Gordon Rankin’s 2 watt 45 SE Bugle).
Now beginning to think that’s the horse driving the cart: I should use a mid (have some good candidates of similar efficiency) and only need to take the mid bass up to eg 300-400 Hz, ie the piston range of a 15".
Rather than depth, I was asking after optimizing midbass –lower mid transient response & impact. Maybe within those parameters it comes down to the quality of the driver and the box construction?
Thanks
I thought a concern of all or most Ks, is a peak at c. 200 Hz, often about 2 dB. Guess it might be notched out, but maybe it’s only the peak giving an illusion of better transient response?
A constraint, and a workaround: I don't want a box bigger than about 70 L (2.5 cubic ft), *but I will use an active “sub” underneath which goes deep, crossing about 60 – 80 Hz
The tapped horn or a TL would be an alternative to the sub.
I apologize for digressing to the next ~3 octaves above what a TH can cover.
The HPL's specs are:
Fs 43
Re 4.7
Qms 4.9
Qes 0.36
Sd 880 cm2
Vas 192 L (6.8 cubic ft)
Xmax 7.0 mm (0.28”)
Le 0.25
With the low Le, I had one steam of thought that the 2035 could be used even to say 1200 Hz without too much distortion(?), avoiding the need for a mid driver. The idea of avoiding a mid driver is one less crossover, less induction losses, and allow a sweet low powered amp (Gordon Rankin’s 2 watt 45 SE Bugle).
Now beginning to think that’s the horse driving the cart: I should use a mid (have some good candidates of similar efficiency) and only need to take the mid bass up to eg 300-400 Hz, ie the piston range of a 15".
Rather than depth, I was asking after optimizing midbass –lower mid transient response & impact. Maybe within those parameters it comes down to the quality of the driver and the box construction?
Thanks