No the problem is not the filter (although you should be using a high pass filter in your sims). The high pass is meant to protect the driver below tuning. If the slope of the filter is so shallow that it's affecting the excursion peak INSIDE the passband that's a problem, not a solution. Your high pass filters shouldn't be having any big effects an octave above the low knee.
You seem to be searching for a magic bullet to decrease excursion while keeping the cab size and the tuning the same. It isn't going to happen. It's physics. If it was possible we would all be doing it and these designs you are looking at would be obsolete.
You seem to be searching for a magic bullet to decrease excursion while keeping the cab size and the tuning the same. It isn't going to happen. It's physics. If it was possible we would all be doing it and these designs you are looking at would be obsolete.
I'm not. You may didn't get my point. I'm just trying to understand if the driver I have available can fit this cab. Once the results shown hi diaphragm displacement it was a concern but, once my simulation is alight with the others guys, there is no more worries. The concern came just because people didn't shared too much results about displacement and I was confused trying to get safe place thru a member with high experience.
Brian's comments are totally relevant.I know that a revision of the TH18 design is long overdue and that it should utilize all the internal volume and incorporate the volume of the speaker cone in the horn path. This is best achieved by reshaping the internals as adding extra material to get cone compensation reduces the volume even more.
The link I posted to Epa's drawing shows my preferred layout of the internals.
The only reasoning behind not posting an update is due to this making the design even more of a Danley clone which was not the original intention.
Be careful about squeezing S2 too much though, it could kill a driver.
JAG given the parameters posted what would you recommend as the best driver
and filter settings I,m interested!
The link I posted to Epa's drawing shows my preferred layout of the internals.
The only reasoning behind not posting an update is due to this making the design even more of a Danley clone which was not the original intention.
Be careful about squeezing S2 too much though, it could kill a driver.
JAG given the parameters posted what would you recommend as the best driver
and filter settings I,m interested!
I haven't studied this design much but we have been discussing it a bit in another thread. The parameters I have are what I was given, it doesn't reflect the most recent version of this horn, it's basically the design from post 1 using the 18 Sound driver as described in post 1.
A quick sim suggests the 18 Sound driver is not even close to ideal (it wants a much larger horn).
I didn't sim a high pass filter, but generally speaking 4th order BW high pass filters work well, they fix the out of band excursion issues without affecting anything inside the passband too much, whereas a 2nd order high pass will affect response in the passband way too much. So an ideal filter would probably be a 4th order BW (or similar slope) filter at whatever frequency is required to keep excursion below tuning in check.
As far as ideal driver - I have no idea, I just know that the 18 Sound from post 1 isn't it. If you want to give me the most up to date Hornresp inputs (for the design that uses all the "dead space" at S1 and has the "cone correction" feature (a bit of a notch in the line cross sectional area where the driver is), and give me a list of 10 or less drivers (with t/s parameters) I can sim them and give you my opinion on which is the best choice.
(EDIT - To be clear the following is a note to everyone, not Xoc1 in particular.)
Also, IMO this nonsense about not posting Danley designs or stuff close to Danley designs isn't helping Danley in any way or benefiting anyone here either. This stuff is on the internet already so what's the point. I did a quick search for the TH118 yesterday and I found a drawing with dimensions. I don't know if it's the real deal or not (didn't even check where it came from) but I posted it in response to a question about a restriction between a cone (throat chamber) and a horn path (S2). So what? It's already out there. Everybody around here was going nutty when the TH_Spud plans were "leaked", but now we're not posting Danley designs out of respect? Please. If you (and I'm not talking about anyone in particular here, just everyone) searched for the TH_Spud plans and looked at them (we all did) I don't want to hear this pretentious crap about withholding information out of respect for a company that makes a ton of money off people including diy people - lots of people on this forum have bought dsl products as a direct result of us talking about them constantly. Every time we talk about dsl products we are helping their business, not hurting it. Even if plans and dimensioned drawings are posted. People that build from plans were never going to buy anyway, while people that buy wouldn't build even if plans were available - but they DO buy because the products are constantly discussed. Many of the people complaining about this have posted drawings of other commercial products, so to exclude this one company is a bit weird. We are here to learn - reverse engineering is a vital part of that process.
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TH-18 "Superwide"
Thanks for this design. I built a pair of extra wide ones and they do exactly what I want them too.
I built a pair 900mm wide to the same plan and they "sound" really low. Loaded with generic Behringer 18" sub drivers and a bridged iNuke 3000.
I've since acquired a pair of TOA HLS46UL2-8's which seem a bit more robust but I haven't tried them yet. I might just build another 2 cabs!
I haven't got any way to measure them or pics because I'll be in a different country for the next 3 months. 2x Eminence 15" scoops stack on top of them perfectly.
Thanks for this design. I built a pair of extra wide ones and they do exactly what I want them too.
I built a pair 900mm wide to the same plan and they "sound" really low. Loaded with generic Behringer 18" sub drivers and a bridged iNuke 3000.
I've since acquired a pair of TOA HLS46UL2-8's which seem a bit more robust but I haven't tried them yet. I might just build another 2 cabs!
I haven't got any way to measure them or pics because I'll be in a different country for the next 3 months. 2x Eminence 15" scoops stack on top of them perfectly.
JAG had recently posted up an FR graph comparing the output of the TH18 to the TH118. They're pretty close, and assuming the mic wasn't moved between measurements, the TH118 seems to go slightly lower but have slightly less output @ 50Hz, suggesting a lower 'Q' around the corner frequency. The impedance curve does suggest a lower resonance frequency than the TH18, so I'd expect a result like that. Addressing the layout and including cone compensation will probably bring the response of the TH18 even closer to that of the TH118.
Yup, it's probably the best approach, though the method I used for cone compensation in the POC4 design is a bit simpler to implement and gets pretty close. I might update my design spreadsheet to include Epa's approach at some point, but haven't really seen the need for it yet. And yes, experimentation suggests that one has got to be careful to not "pinch" S2 too much - if this happens, there will be a measureable decrease in efficiency too, based on my tests with putting a pinch @S2 in my POC3.
Can you put a link on that post? I made comparative measurements half a year ago with hornresp but I never did impedance measurements. And even though the drivers were with different impedances (RE 3,4 ohm original vs 5,7 ohm mine), the traces were extremely similar. Even at high SPL the response stayed the same and they had almost the same distortions. Mine probably had stronger and heavier wood and better bracing. The DSL went a bit louder but because of the impedance difference and the Powersoft K8 behavior which is more stable at lower impedance, I cannot say if it was a difference from the subs themselves or the amp.
The post containing the measurement is here - http://www.diyaudio.com/forums/subwoofers/190635-th-18-flat-35hz-xoc1s-design-221.html#post4698461
Here's a copy of the picture of the measurement -
An externally hosted image should be here but it was not working when we last tested it.
Oh, that was my post. I thought there was another one with an impedance measurement included.
Unfortunately I will not have access to another DSL sub to soon, so I will not take another sweep with them
But I still have the Xoc1 TH18 with 18SW115-8 in them and I will take some time to measure ground plane soon. I got also a FP14000 clone with the new power source that can sustain probably close to 4 KW long term in bridge and 14 Kw CEA bursts. So if you would like me to do some tests, tell me.
Regarding the bracings, I will put an horizontal brace in the mouth, I have the wall in front of the baffle inside very strong, the next section with two braces and then a single central line up to the mouth. It is a very strong plywood, 13 ply from Ukraine, tough but heavier than the one in the original, probably10 kg more.
In the TH115 they used a ferrite driver, in the TH118 they used an 18sound NLW9600 for a while then changed to an 18SW115-4
Hi radulescu,
Post #2352: "...I will put an horizontal brace in the mouth, I have the wall in front of the baffle inside very strong, the next section with two braces and then a single central line up to the mouth..."
That sounds like substantial bracing. An impedance and SPL run @ 2.83Vrms would be a good reference to have and study.
Regards,
Post #2352: "...I will put an horizontal brace in the mouth, I have the wall in front of the baffle inside very strong, the next section with two braces and then a single central line up to the mouth..."
That sounds like substantial bracing. An impedance and SPL run @ 2.83Vrms would be a good reference to have and study.
Regards,
Hi Oliver,That would result in a solid 9% (or 10% the other way round
Yes indeed, and now it all sounds simple...
To make things more exiting again ;-) technically speaking is the DSL TH118 horn-path shorter than the horn-path of the Xoc1-TH18.
Regards,
Djim
As I mentioned in PM it's really the ground plane impedance measurement of the commercial TH118 that we need. I understand that isn't going to happen anytime soon, if at all.
Maybe others would like to see various measurements of the TH18, but the TH118 impedance is really the only thing that I really wanted to see.
Thanks anyway.
The impedance measurement being talked about is the one from the TH118 spec sheet on the dsl website. That's the measurement causing all this big fuss.
The TH18 is only a few inches shorter than the TH118. It's a result of the horn path going directly through the cone, which adds a few inches right near the beginning of the flare and a few more inches going through the first 180 degree bend right above the driver.
This seems silly to discuss the intimate details of the inner workings of the design but considering it taboo to post a picture. Looking at a picture makes it very clear that the TH118 path is a few inches longer and why. And pictures are readily available if you do a quick search.
These few inches of extra path length will amount to maybe 1 hz lower tuning, if that. As the measurement above shows, these two designs are already quite similar.
This seems silly to discuss the intimate details of the inner workings of the design but considering it taboo to post a picture. Looking at a picture makes it very clear that the TH118 path is a few inches longer and why. And pictures are readily available if you do a quick search.
These few inches of extra path length will amount to maybe 1 hz lower tuning, if that. As the measurement above shows, these two designs are already quite similar.