Tweet
I may be off base but I wonder if the absolute sensitivity means anything. I usually use the mid level as the reference and adjust the woofer and tweeter levels to match.
-
-
It does if you're using a low power (tube) amp, because that defines your SPL capabilities.I wonder if the absolute sensitivity means anything.Comment
-
Originally posted by Saurav
Tubes also likes fairly constant impedance(small swings) not large swings.Comment
-
It depends on how you are doing things. If you go active, you can of course do that. However in a passive xover you can't easily pull down the sensitivity of the woofer. At least not with very large resistors that handle lots of power. In general just not practical.Originally posted by BobEllis
As mentioned, with tube amps you typically rely on the efficiency to get your output. Also as stated, you typically want nice flat, smooth impedance curves. This is one of the reason the tube guys typically love drivers like the TD15M. A very flat impedance curve from must over resonance up to 5KHz or so and 97dB 1W makes it very simple to drive with a tube amp.
JohnComment
-
I'm curious to see what you find out with them. I was thinking of going with the PHL 1120, but we'll see. Do you have a build thread started on HTS or anywhere?Originally posted by mayhem13Comment
-
Not yet Looney, Trying to settle on a tweeter to match with these. Also thought i might piggyback on Augerpro, he's currently testing these in a 3 way baffle right now. The mid/high xover point concerns me so when i get some feedback from him, i'll choose a tweeter. Not going to use a compression driver though-Vifa dome or Ciare dome maybe.Originally posted by looneybomberComment
-
Here is a little update on where I'm at with my Bagby/Salk inpsired design. Attached is a pdf of the plans as they stand. I have the Peerless HDS tweeters in hand and the Lambda's being made.
I've been doing some box modelling for the Lambda TD12H in Unibox. Below is a copy of the model I have using a 3"x7.25" port at 50watts input. At 60w input the port reaches the 26m/s port speed, but I'm up to almost 109db output at that point, so my thinking is that it is ok to use this smaller port size. The port is also to the rea of the box. If I go up to the next typically availabe size, a 4" dia., then the port length jumps over 13", which would require a bend in the port to fit. I'd be interested in other thoughts on the bass tuning and port size.
I've also been doing some diffraction modelling in BDS. Here is the results for the two drivers:
I've also done some diffraction simulation and dipole simulations in John k.'s ABCDipole. Attached are the diffraction and then dipole simulations:
Finally, here are some results on woofer/midrange floor bounce nulls. I'm thinking of a crossover point in the 500hz-600hz range.
What do you all think?Dan N.Comment
-
Hi Dan, the paperwork I have seen shows that as vent velocity reaches over 10m/s, distortion becomes audible. I typically like to do some kind of a slot port going in along the bottom of the enclosure, then up the back of the enclosure, and if necessary back towards the front on the top. Put a 3/4" or more radius on the inside of the 2 pieces that form the bend, and a small 45degree piece about 1.5" or so in the corners as well.Originally posted by dlneubec
If you went with a 12" wide x 1.5" tall slot vent you would need 22" length which is quite easy to come up with if you go in along the bottom and then up the back. This would keep vent velocity down below 10m/s up to 100W input.
JohnComment
-
Ahk! John, I did slot ports in my last two designs and was hoping to cop out on the easier way this time. When you have a sloped front baffle, it's a little more difficult getting the slot to match on the back side of the baffle. One thing I like about slot ports, however, is that they are much more flexible for tuning to an exact area as compared to round ports. I guess you're right, I should probably do this one the hard way also! :cry: I'll take a look at it further.
Thanks for the suggestion.
BTW, what do you think of the box size and tuning for the TD12H? I think Jeff used a smaller box and a flatter tuning with a bit higher fb and f3.Dan N.Comment
-
Dan,
The immediacy and impact of a high sensitivity system is hard to ignore, but I don't want to have a ragged FR or higher non-linear distortion to achieve that.
Have you looked at the custom 8" SEAS midrange specced by Troels Gravesen?
Allegedly sounds great. Perhaps you could go oner further and enquire about getting an Excel based motor in there...
Comment
-
Yes, I did see this design. I was not able to find that Seas driver available anywhere. It looks to me like the posted FR of the JA8008 is not any smoother than the PHL or the B&C I have been considering. I have no data on the distortion profile of the JA8008 that would suggest it is cleaner in the intended operating range than the others. I can tell you from personal experince that the PHL sounds fantastic in Jeff's speaker.Originally posted by tktranDan,
The immediacy and impact of a high sensitivity system is hard to ignore, but I don't want to have a ragged FR or higher non-linear distortion to achieve that.
Have you looked at the custom 8" SEAS midrange specced by Troels Gravesen?
Allegedly sounds great. Perhaps you could go oner further and enquire about getting an Excel based motor in there...
http://www.troelsgravesen.dk/JA8008_response.htm
It occurs to me that since he is using it in a 2way design, not as a dedicated midrange, he might make a different midrange choice if he were designing a high efficiency, passive 3way.Last edited by dlneubec; 15 May 2008, 07:43 Thursday.Dan N.Comment
-
Hi Dan, looking good! Two questions: what made you decide on the TD12H versus the other models. and what floor bounce program is that?Comment
-
I had the same question when I saw that screenshotand what floor bounce program is that?
Google "Floor Bounce Crossover Calculator" and the first link is boxycad2.xls.
Comment
-
I think calculating floor bounce is a little simplistic. The ceiling in my living room isn't all that much farther from the mid than the floor so you ought to at least include the ceiling. And that says nothing about the 4 walls.....Comment
-
Dennis I'm doing the calculation with paper and pen right now so anything to speed up the procedure would help :W
Good point about the other main reflections. I wonder though if a *typical* room has the walls and ceiling far enough away from woofer the bounce occurs very low in frequency?Comment
-
Yes it is BoxyCad2. I'd say it can be used to analyse bounce from about any surface, as long as you plug in the right info. However, the closest surfaces are the ones that will show nulls higher in frequency where they are more likely to cause crossover issues. For example, in the plot below, I adjusted the midrange and woofer heights as if they were measured from the ceiling (assuming an 8' ceiling) rather than from the floor. You can see how the ceiling bounce null frequencies dropped way below those in the floor bounce calcualtions.Originally posted by Dennis H
Dan N.Comment
-
Originally posted by augerpro
Hi Brandon,
Sorry, I missed this question. The only feedback I received on this choice was from Jeff B. He is very happy with how the TD12H matched the PHL in his design. He did some modelling in his crossover with my other midrange option, the B&C 6md38 and said it worked very well. Also, the next likely choice, the TD12X, took an 80L box to get the extension the TD12H got in a 45L box, though it is a couple db more sensitive.
Since Jeff had already been successful matching the TD12H to the PHL and the box could be smaller, which met one of my criteria or making keeping the speaker mass down, I decided just to go forward with the TD12H. This choice allowed me to reduce the depth and height of the bass bin and increase the height of the open baffle panel, which in turn improved the dipole model by reducing the dipole peak and dip right after.Dan N.Comment
-
dlneubec: You modeled the TD12h with 50w. Is this how much power you're planning on using? The reason I ask is the lambda woofers can handle quite a bit more power and if you're using a relatively low powered amp, you could get by with a cheaper woofer(s) to help cut costs.Comment
-
I was using 50w as a possible scenario for typical listening and port sizing, however, I have as much as 225w/ch to use, so I have decided to probably go for port size able to handle more like 150 watts instead, but I'll probably use a slot port so I can fine tune it better.Dan N.Comment
-
Any updates on this project ? Really curious here...Comment
-
This will be moving rather slow for awhile. I need to force myself to finish up the veneer and other finishing on my SounRounds and Duo designs before I start making dust on this design :boohoo: I'm trying to get them ready to go to the Dayton DIY on July 11th-12th.
That said, here is the current status with the design. I have ordered the Lambda woofers and I'm waiting for them to be built. I have been doing some final box modeling for the bass bin and dipole/diffraction modeling in ABCDipole and the Edge. Below are graphs of the Unibox model and the Edge model showing dipole and diffraction results. The intended crossover points are in the range of 450hz-500hz woofer to mid. Also I've included a pdf of the plans as they stand to date.
Dan N.Comment
-
dlneubec,
If I remember correctly Jeff is doing testing/simulation for you on the mid-range, B&C, 6DM8 you are interested in. Any report on this mid-range yet, it looks interesting to me as well. If you any thing to show us I would welcome it.Comment
-
Jeff has looked at the driver (from published specs only) and did an analysis of it in his original crossover design, specifically to test xmax performance at the low end. He has said it looks like a very good replacement for the PHL and there are no Xmax issues.
Neither of us have measured results from the driver, however. When I get caught up on the other projects, I plan to buy one and test it.Dan N.Comment
-
I just picked up some unbacked veneer for this project. It is Sweet Redgum. I got over 71 sq. ft. (24 pieces @9.5"x45") for just $24.99 plus shipping. I will use it on the box for sure and maybe the baffles, though I'm thinking of doing the baffles out of solid hardwood with a mdf or hdf backer. Below is two pieces side by side and overlapped. There is a light streak on both edges with the dark running down the middle. With both dark and light colors in the veneer, I can go with a dark or light hardwood on the baffles or maybe bookmatch the veneer.
Dan N.Comment
-
Wow, that is gorgeous veneer!Comment
-
How's that 5 day thing working out?I have ordered the Lambda woofers and I'm waiting for them to be built.
Comment
-
It looks like things are running a little behind, but that also includes weekend days, so maybe not much. :BOriginally posted by Dennis HHow's that 5 day thing working out?Dan N.Comment
-
The TD12H comes with a satin finished phase plug. To match that look, I thought I'd use these brackets to attach the mid/tweeter baffle to the bass bin. It is satin finshed stainless steel and rated at 44lbs each. That's not strong enough to pick the speakers up by, but plenty to handle the baffle. I had a lot of other ideas for attaching the baffle, but they were all much more complicated to implement.
Dan N.Comment
-
Hi Dan,Originally posted by dlneubec
I believe these were shipped today, but we have a bunch of Lambda woofers going out tomorrow as well. I don't have access to UPS Worldship at home, but hopefully you were sent tracking info by Tavia today. I'll verify in the morning. The woofers were actually finished and sprayed with the damping treatment on friday. Normally they would have been tested and packaged monday, but Jason was off for the day.
We have been getting really slammed with orders since the Jim Salk/Jeff Bagby design using the Lambda woofers came out. We have quite a few woofers in the queue right now but we're doing our best to get them out quickly.
JohnComment
-
My veneer should be here today. The Lamda's were indeed shipped on Tuesday, so will be here very soon. Too bad I'm not ready to start building them yet!
A question was raised by Saurav in the Dipole Design Questions? thread about how I modeled the diople response in regards to the open baffle mid. Did I use just the open baffle mid in the model or the entire baffle to the floor, which would include the bass bin baffle. The answer is I did it both ways and compared them. I thought I'd post the results here as well. The graphs (from the Edge) show the open baffle results (red) and the diffraction results (green). The first graph is the mid baffle only. The second graph expands the baffle to include the bass bin baffle all the way to the floor.
BTW, the Edge doesn't allow for inclusion of edge treatments, like chamfers or round-overs, so these graphs don't reflect the chamfers shown in the plans. FWIW, I also modeled the baffles in BDS, which indicated a noticeable improvement in the diffraction signature for the mid response and marked improvement for the tweeter with the chamfers as compared to without.
Dan N.Comment
-
Yeah sorry about the slight delay in shipping the drivers out I had to go check out the body worlds exhibit at the museum before they get rid of it in June.
Cant wait to see the pictures of these cabinets that veneer looks really nice!Comment
-
There is not a lot of activity going on with this project since I'm applying finish to two other projects first, but the plans are coming together (see attached pdf). I received the Lambda TD12H drivers. They are georgeous to look and and very heavy! :T :T I'll take some photo's and post them soon. I have yet to order the mid drivers.
The veneer choice has changed. My wife likes the look of Bubinga better, so below is what I have on the way. I'm still thinking of using a contrasting (light) hardwood on the front baffle and the Bubinga on the box. Since the Bubinga is so rich in color and texture, it may be something simple like Maple or Ash. I've found some speaker spikes, binding posts and brackets to hold up the open baffle that I have also ordered, shown below. They all match pretty well with the semi-polished silver phase plugs on the Lambda's.
Dan N.Comment
-
I like the aesthetics of your enclosure, gonna look sweet I'm sure.Comment
-
We've actually used sets of the phase plugs for floor spikes before. They just screw on with 1/4-20 set screws. Only issue is that they are big and expensive.Originally posted by dlneubec
JohnComment
-
Is that what Jim did on his? They sure looked like they could be the same size. I did not really want to use something quite as big in this case anyway and the smaller ones seemed just about right.Dan N.Comment
-
Hi Dan,
How do you intend to finish the Bubinga?
regards,
Thanh.Comment
-
I haven't yet considered what finish I will be applying for this project, though it will be not be stained.
I'm using Bubinga on a my SoundRound project and started out with a high gloss finish. However, I thought the figure in the veneer became almost too dominant, so I'm ending up with a satin finish. I'm beginning to think, at least on larger speakers, that smaller, more visually busy patterns (like Bubinga) look best with a more muted satin finish, while larger patterns (Like Santos Rosewood) look best with high gloss.Dan N.Comment
-
Hi Dan,Originally posted by dlneubec
Watching your project with great interest. One thing I like to find out is why you using 4ohm TD12H and not 8ohm?
Not sure if Jeff B is still reading this thread. Would like to know if Audax PR170MO is considerable if high SPL is not a requirement? 15W on the Audax will be something like 105db. Which is more than enough for my personal enjoyment.
BTW, how loud can a dome tweeter play? Something like Vifa DX25?Comment
-
I'm using the 4ohm Lambda TD12H because Jeff recommended it. His reasoning is that his measurements show that it is really closer to an 8ohm than a 4ohm driver, in the impedance sweeps he took.
As to the Audax, I think the issue was lack of Xmax at the low end. I have not looked at it, so i can't tell you at what level it will exceed Xmax, but Jeff had considered it and rejected it as it failed this critical test. He has a special tool he uses to model this. Perhaps Jeff can chime in further here.
I'm not a driver expert, so perhaps others can answer more acurately. I suspect part of the issue, again, is Xmax and at what point the driver will exceed it at a given crossover point, slope and spl level. Perhaps thermal limits for dome tweeters are reached sooner as well.
DanDan N.Comment
-
The manufacturer recommends a 2nd order filter at 500Hz. Over on diyaudio some people have used it down to 250, but the consensus seems to be that it sounds best with LR4 @ 350-400. Linkwitz's spl_max spreadsheet says that the driver is capable of 103dB @ 400Hz (106dB for dipole).
If you look at the graph on Madisound, the PR170M0 is about 95dB/W through that region (the specs say 100, but the graphs don't), so 103dB = 8W, 106dB = 16W.
I'm driving mine with a 4W amp in a fairly small room, LR4 @ 450Hz, so (a) I don't think I'm reaching Xmax limits, and (b) it plays loud enough for me. If you were trying for a higher output target, or a design intended for a larger room, 1 PR170M0 per side probably wouldn't be enough. Many people use it in an MTM.
What tweeter are you considering with it? I have a Fountek JP3.0 ribbon, and I measure the Audax 3-4dB more sensitive than the Fountek. Which matches some people who say it's about 97dB/W/m, not 95 or 100 (I haven't calibrated my setup for absolute SPL measurements). For my next project I'm thinking of trying a compression tweeter+horn/waveguide, because I don't want to pad the midrange driver. But the problem with cheap horn tweeters is that they sound like... cheap horn tweeters. The B&C DE10/ME10 tweeter/horn pair gets good reviews, so I might try that. If that shows promise, I might step up to the BMS/DDS combo.
You also have to loosen your rules a bit with the tweeter XO. I've used this driver up to 3500-4500, and it sounds fine to me (though I'm no expert), but you're definitely into cone breakup by then. It's a paper cone though, so it doesn't sound as bad as a metal cone would. I've seen some people use it 'full range', or 1st order XO @ 7kHz, or things like that... I tried it, and it starts to sound pretty rough by that point. I'll probably aim for 2500-3500 with the next speakers, depending on what the horn can do.Comment
-
If you want to save some money in the long run go straight to B&C De250/DDS combo that will give x-over at min 1.7Khz, whereas DE10/ME10 x-over at 2.5Khz.Originally posted by SauravComment
-
I've been following your experiments with these drivers. You may be right, and I may end up using that combination.Comment
-
A question for Nick McKinney....
How far out (in months or years) is your Altec/Western Electric mid? I have been trying to figure out how to do a two way without using a compression driver and one of the alternatives I can up with was the Beyma TPL-150 on the TD-TPL horn....but your midrange/fullrange driver sounds awfully tempting.
Thank you,
ChrisComment
-
Originally posted by chrismercurio
I answered on the other site, I just now saw this one here.
For those interested that didn't see the other response, basically as fast as the cone supplier can get me the cones. Could be as fast as 3 months, maybe longer, its out of my hands at the moment. The ceramic motor design is basically done, and we would be doing an Alnico version as well.Comment
-
dlneubec,
I am interested in this project. Any progress report on this project is welcome.
cheers.Comment
Comment