Was enjoyable following these from last year. The trap (first time I saw one) was enlightening along with Bill's explanation and measurements. Again, great sounding as ever....
Thanks, everyone! I was planning on another crossover modification, but after all the positive feedback I have received after Iowa and now Indy, I think I am going to leave the crossover alone and declare this project DONE!
I agree. They do everything well. The only thing I might consider is a port approach similar to what John Hollander did on his silver nano speakers to avoid all the PVC sticking out the back.
Keep an open mind, but don't let your brain fall out.
No offense but I don't understand the value in this design. A 3 liter box but another 3 liters of fugly pvc pipe behind it. I'd rather just have a 6 liter box and keep the unsightly plastic plumbing hidden internally. Was this driven by Wolf's competition criteria?
Yep, to meet the nanotech challenge. Im sure if someone wanted to copy the design, the volume could be increased accommodate the port or incorporated via slot port as John did.
One of the aspects that made Bill's intersting was the trap he used to greatly reduce the port resonance. And that with his design vs the other entry using the same woofer with dual prs, Bills was noticeably more sensitive though tuning was very similar.
No offense but I don't understand the value in this design. A 3 liter box but another 3 liters of fugly pvc pipe behind it. I'd rather just have a 6 liter box and keep the unsightly plastic plumbing hidden internally. Was this driven by Wolf's competition criteria?
Yes the rules specified the internal volume had to be 3l or smaller, however XO and ports could be put outside that so long they fit inside a 12" cube. I agree the rules were a little wonky, I took the 3l restriction more literally in my design and kept everything inside the 3L, which forced the use of passive radiators.
However there is no denying that Bill's implementation of this design w/in the rules resulted in a very optimal speaker. While it was quite a bit larger than many entries, Bill did some very neat things with the port tuning and the resonant H-chamber to really justify his effort and the use of the extra space.
No offense but I don't understand the value in this design. A 3 liter box but another 3 liters of fugly pvc pipe behind it. I'd rather just have a 6 liter box and keep the unsightly plastic plumbing hidden internally. Was this driven by Wolf's competition criteria?
I admit to having somewhat mixed feelings about this. At the end of the day, it was in line with the rules of the competition and it is a very good sounding design. If one enclosed the port and let the whole thing be more like 6 liters, it would still be one of the best speakers that size that I have heard.
When Wolf set the 3 liter criteria, one of his stated objectives was to be smaller than popular "small" speakers such as the Overnight Sensation (which is something like 4 to 4.5 liters). The overall aesthetic impact of the "Plumbers Delight" is of something larger than the Overnight Sensations. The upside of the approach is that it brings attention to the port resonance issue and demonstrates a solution. I don't want to speak for John H., but I strongly suspect that this design had an influence on what he did for his silver Peerless based nano entry, which was a more elegant solution based on the same principle.
If I were running such a competition, I would set the size criteria based on external size, which would have created a more level playing field and maybe spurred some different innovative solutions. But then, this speaker probably would not have been built - and I am glad it was built...Food for thought.
Keep an open mind, but don't let your brain fall out.
Ben and I talked at length about the criteria. Doing something different was just part of it. Size wise, keeping everything within a 12" cube was the "external" limit.
I agree Scott that Johns solution is more appealing and elegant. However, as John can attest he was not able to reduce both peaks as Bill did. I'm sure with further design that he would though.
Ben and I will be discussing next year's theme soon. And he will again use a poll to determine what it will be.
One question for those that attended. What did you think of the tournament format?
Ben and I talked at length about the criteria. Doing something different was just part of it. Size wise, keeping everything within a 12" cube was the "external" limit.
I agree Scott that Johns solution is more appealing and elegant. However, as John can attest he was not able to reduce both peaks as Bill did. I'm sure with further design that he would though.
Ben and I will be discussing next year's theme soon. And he will again use a poll to determine what it will be.
One question for those that attended. What did you think of the tournament format?
Overall I liked it and it was helpful to compare speakers with similar specs to each other.
My only suggestion is make more "open play time" for the theme speakers, my speakers only played for the demo music and never came out again, would have been fun to have another 5 mins to show off what they did well with my own reference music.
No offense but I don't understand the value in this design. A 3 liter box but another 3 liters of fugly pvc pipe behind it. I'd rather just have a 6 liter box and keep the unsightly plastic plumbing hidden internally. Was this driven by Wolf's competition criteria?
No offense taken. And I agree completely with your comments. However, having said that, this design would not have taken place had I not put the port on the outside of the box. Because an internal port is very difficult to tune and modify, I would have given up before getting it tuned properly. .
The original port was 26" long with no trap. And it sounded and measured bad, with large 1st and 2nd port resonances. I was going to give up and re-tune the box from 40Hz up to about 50Hz by cutting the port down to about 12" or so. This would have created a peaky 50Hz boom box. But then I came up with the trap idea and, because the port was on the outside of the box, it was very easy to construct it and tune it. I had OmniMic running continuously taking near field port measurements as I swapped out different trap lengths and stuffing densities on the fly. When I got done, I had a big pile of rejected trap stubs laying on the floor.
Ben and I talked at length about the criteria. Doing something different was just part of it. Size wise, keeping everything within a 12" cube was the "external" limit.
I agree Scott that Johns solution is more appealing and elegant. However, as John can attest he was not able to reduce both peaks as Bill did. I'm sure with further design that he would though.
Ben and I will be discussing next year's theme soon. And he will again use a poll to determine what it will be.
One question for those that attended. What did you think of the tournament format?
I really liked the tournament format. My sonic memory is very short and this helped a great deal.
I liked the tournament format, but missed the designer comments. If we could have formalized the discussion after the first round that would have been great.
Bill, That was A LOT of work! I like your port resonant trap. Do you have a Z measurement with and without? Also, NF/port summed with and without?
If you have ever seen the weird shape of Vivid speakers, even the Nataulus thats what L. Dickie (the desiger) uses the cabinet shape for. That, and diffraction. It is very cool stuff as a whole and I think your exexution of dampening a port's resonance is awesome.
Great document package, too. 3 ohms Z for a 4 ohm speaker is no big deal. Many commercial 8 ohm speakers drop to 3.8. It is a little reactive and 80HZ looks to be a hell of a load which could account for the distortion spike as you are pulling a ton of current and back EMF will be at a maximum. Would not be a problem with amps, just make them complain a little and by the looks of it, it is likely more of something that is measurable....Not meaningful.
Specially in such a tiny speaker!!!!!
I bet they actually are stunning at regular to moderate volumes. I am very impressed with this design.
Update:
Mike, you asked me a while back if I had run a Z curve with and without the trap. But the traps were already glued in place.
Well, I accidently bumped and knocked one of the port traps off one of my speakers. So, before gluing it trap back on, I ran a system impedance curve comparing trap verses no trap. The purple curve is with the trap removed & plugged with a rubber stopper; the green curve is with the trap in place.
As you can see, there is no difference at the 1st & 2nd port resonances of 260 & 520Hz. There is a slight difference between the two curves in the 40 to 80Hz range. My guess is that the 1st & 2nd port resonances have little to no effect on the impedance curve because these resonances are created by the smaller volume of air inside the port and therefore tend to be isolated somewhat from the larger amount of air inside the box. As to why the slight change from 40 to 80Hz, I have no idea.
Comments
Ron
Bill
Sehlin Sound Solutions
One of the aspects that made Bill's intersting was the trap he used to greatly reduce the port resonance. And that with his design vs the other entry using the same woofer with dual prs, Bills was noticeably more sensitive though tuning was very similar.
However there is no denying that Bill's implementation of this design w/in the rules resulted in a very optimal speaker. While it was quite a bit larger than many entries, Bill did some very neat things with the port tuning and the resonant H-chamber to really justify his effort and the use of the extra space.
Javad
When Wolf set the 3 liter criteria, one of his stated objectives was to be smaller than popular "small" speakers such as the Overnight Sensation (which is something like 4 to 4.5 liters). The overall aesthetic impact of the "Plumbers Delight" is of something larger than the Overnight Sensations. The upside of the approach is that it brings attention to the port resonance issue and demonstrates a solution. I don't want to speak for John H., but I strongly suspect that this design had an influence on what he did for his silver Peerless based nano entry, which was a more elegant solution based on the same principle.
If I were running such a competition, I would set the size criteria based on external size, which would have created a more level playing field and maybe spurred some different innovative solutions. But then, this speaker probably would not have been built - and I am glad it was built...Food for thought.
Sehlin Sound Solutions
I agree Scott that Johns solution is more appealing and elegant. However, as John can attest he was not able to reduce both peaks as Bill did. I'm sure with further design that he would though.
Ben and I will be discussing next year's theme soon. And he will again use a poll to determine what it will be.
One question for those that attended. What did you think of the tournament format?
My only suggestion is make more "open play time" for the theme speakers, my speakers only played for the demo music and never came out again, would have been fun to have another 5 mins to show off what they did well with my own reference music.
Javad
The original port was 26" long with no trap. And it sounded and measured bad, with large 1st and 2nd port resonances. I was going to give up and re-tune the box from 40Hz up to about 50Hz by cutting the port down to about 12" or so. This would have created a peaky 50Hz boom box. But then I came up with the trap idea and, because the port was on the outside of the box, it was very easy to construct it and tune it. I had OmniMic running continuously taking near field port measurements as I swapped out different trap lengths and stuffing densities on the fly. When I got done, I had a big pile of rejected trap stubs laying on the floor.
Update:
Mike, you asked me a while back if I had run a Z curve with and without the trap. But the traps were already glued in place.
Well, I accidently bumped and knocked one of the port traps off one of my speakers. So, before gluing it trap back on, I ran a system impedance curve comparing trap verses no trap. The purple curve is with the trap removed & plugged with a rubber stopper; the green curve is with the trap in place.
As you can see, there is no difference at the 1st & 2nd port resonances of 260 & 520Hz. There is a slight difference between the two curves in the 40 to 80Hz range. My guess is that the 1st & 2nd port resonances have little to no effect on the impedance curve because these resonances are created by the smaller volume of air inside the port and therefore tend to be isolated somewhat from the larger amount of air inside the box. As to why the slight change from 40 to 80Hz, I have no idea.