Building an Enclosure Around a D.A.S D-401 2395 Clone

[robertg]

I'm not going to win and design awards. I think a wooden horn would look better than the large DAS lens.

I'm doing the cabinets in rosewood, and probably paint the baffle blue.

[RMC]

Hi Robert,

Doesn't look bad to me. We don't build boxes to win awards, but for our listening pleasure, remember that. My numerous boxes aren't sexy but they are technically correct. That's what matters in my view. Let us know how yours sound...

Richard

[ivica]

I'm not going to win and design awards. I think a wooden horn would look better than the large DAS lens.

I'm doing the cabinets in rosewood, and probably paint the baffle blue.

Hi robertg,
it seems to me tahat You are not going to use MA15 clamps for fixing the driver.
http://audio-heritage.jp/JBL/etc/speakeroption.html
http://www.audioheritage.org/vbullet...l=1#post406251
http://img05.shop-pro.jp/PA01015/403...1704404_o1.jpg


regards
ivica

[robertg]

Hi robertg,
it seems to me tahat You are not going to use MA15 clamps for fixing the driver.
http://audio-heritage.jp/JBL/etc/speakeroption.html
http://www.audioheritage.org/vbullet...l=1#post406251
http://img05.shop-pro.jp/PA01015/403...1704404_o1.jpg


regards
ivica

I wanted to, but the E145 looks to be over an inch thick.

[ivica]

I wanted to, but the E145 looks to be over an inch thick.

Hi robertg,

may be wooden ring round the E145 would help in order to compensate so large distance from the baffle.

regards
ivica

[robertg]

Hi robertg,

may be wooden ring round the E145 would help in order to compensate so large distance from the baffle.

regards
ivica

What would be the advantage of that? Less chance of the basket flexing at the mounting points?

[robertg]

Hi Robert,

The JBL recommended enclosure volumes for a single E-145 is in the range of 3-8 Cu. Ft. or 85-227 liters net(see JBL, E-series, Instruction Manual, 02/81, P. 5). So a box of 9-10 cu. ft. is too large in JBL's view for proper performance. In order to help you "fit" on box top the compression driver/horn/lens assembly, I took the largest proposed volume (8 cu. ft.) and ran a quick computer simulation in Winspeakerz v. 2.5.2 speaker design software.

The T/S parameters used were those of JBL from the E-series brochure (Fs 35hz, Qts .25, Vas 275L./9.7 cu. ft, etc.). In such a box, tuning at 40 hz leads to an about flat response in the bass range. But this woofer has a rising response in the mid-bass like many other Musical Instrument drivers.

After testing a few, my preference would go to a 45 hz tuning (Fb) for two reasons. First, tuning lower usually puts more strain on a woofer (Increased excursion) and you therefore reach X max faster and at a lower output level. Second, the little higher tuning here creates a small bump in response of about 1.5 db at 50 hz which will about match the mid-bass sound level since that driver has a rising response of + 2 db or so from about 200 hz and up. At a flat response tuning of 40 hz, the mid-bass level will be about 2 db higher than the bass level. Giving more emphasis to a mid-bassy sounding speakers. I hate that. The small bass bump would then be usefull to "match, equalize or balance" perceived bass and mid-bass sound levels.

With an F3 (3 db down point) at 40 hz (with 45 hz tuning) this is still lower bass than MOST Sound Reinforcement cabinets sold. To achieve that tuning frequency, the software suggested two ducted ports of 6" dia. and 3.25" long. I think four ducted ports of 4" dia. and 2.55" long might do the job, but I have to check that again since I was in a rush to leave for an appointment today when looking at alternative port dimensions...

Personnaly, I would use a steep (18-24 db/oct.) high-pass filter for below 40 hz. Then, if you wish, you may beat the crap out of it... Although, at the JBL rated 300 watts input (program material), with NO high-pass filter in the lows, Winspeakers indicates you would reach Xmax (7.11mm) at about 37 hz! (111 db) and from about 45 hz and up close to 123 db. Sounds like enough to rattle the silver, as they say. BTW the cone excursion curve shows that the usual bump (here at 55-60 hz) in this curve, just above the 45 hz tuning frequency (Fb), represents about 4.75 mm of excursion at 300 watts out of 7.11 mm... I'm getting excited compared to my 2205H.

I think you'll have to forget your 36.5 inch wide cabinet dimension, as it may not make sense in the circumstances. Don't forget "... no single dimension should be more than three times any other."(same p.4)Also, you should try to avoid cabinet dimensions that are multiples of another dimension (e.g. 12", 24" and/or 36"). In the example below none is > three times another and none is a multiple of the others.

Not counting the volume displaced by the 15" woofer (6L. or 0.212 cu. ft. according to JBL) nor the space taken by proper cabinet internal bracing (? volume), the Winspeakerz software gives me INTERNAL cabinet dimensions of 38.833" H X 24" W X 14.833" D = 8 cu. ft. Naturally, you'll have to add some box volume here (on box dimensions) re driver and bracing space taken. This still gives an idea of what kind of EXTERIOR width and depth you can expect to mount your hardware. If you use 3/4" thick plywood, then your cabinet would be 25.5" wide (maybe a bit more re box overvolume), still less than your lens at 36"wide. But probably still feasible in my view. And I don't think it would look worst, if done properly, than a JBL 4675C Cinema Loudspeaker system for example. Regards,

Richard

After doing some reading there is a misprint on the E145 parameters, the VAS is supposed to be 427.7, not 275. What does this change?

[RMC]

Hi Robert,

What is the source for this "misprint" on E-145 Vas figure ? Who says that ? I re-checked all my JBL stuff and that is their published number (275 liters). It may change things . I will re-do a speaker design run in Winspeakers software with the "revised" Vas number and come back to you soon... One thing that did not seem to change (misprint) is JBL's mention that max appropriate box volume is 8 cu. ft.

Richard

[ivica]

After doing some reading there is a misprint on the E145 parameters, the VAS is supposed to be 427.7, not 275. What does this change?

Hi robertg,
using correct Vas for the JBL E145 and JBL 2235 the comparative response using 150 Lit ( E145 tuned 50Hz,green, 2235 tuned 29Hz, red) .
at about 150W input power

regards
ivica

[robertg]

I'm at 227 l, or 8 cubic feet with three 4" ports that are 1 1/4" long. It looks like the E145 will make a lot of noise.

I downloaded winisd, and it looks like my ports should be longer if I entered everything correct.

[robertg]

Hi Robert,

What is the source for this "misprint" on E-145 Vas figure ? Who says that ? I re-checked all my JBL stuff and that is their published number (275 liters). It may change things . I will re-do a speaker design run in Winspeakers software with the "revised" Vas number and come back to you soon... One thing that did not seem to change (misprint) is JBL's mention that max appropriate box volume is 8 cu. ft.

Richard

It's here.

http://www.audioheritage.org/vbullet...JBL-E145/page2

[RMC]

Hi Robert,

Which Win ISD did you downloaded? ISD Beta or ISD Pro Alpha? In Pro Alpha there is a sequence to follow when entering the data, otherwise that software bugs... In case you need that sequence let me know I have two of those. I did mention here or in another thread that different softwares lead to slightly different results. IF my memory is correct, ISD Pro uses QL 10 as default box loss assumption? Verify that. While others use the usual QL 7 box loss assumption. This may make a small difference in cab volume/tuning.

RE IVICA Post # 39

With all due respect for him, his thing doesn't make much sense in the present context because it means scrapping your present boxes and building new ones of 150L.(5.3 cu. ft.)! Plus your 2395 clones will probably not fit on that the way you wish. Finally, on the response curve he posted himself, the woofer's rising response that I mentioned previously (+2 db from about 200 hz at 1 watt) would become your worst nightmare at high sound levels: his curve shows at 50 hz about 118 db and at 250 hz or so about 125 db... With a now 7 db difference as level is increased, this thing is prone to huge mid-bassy sound which is unacceptable sound wise (poorly balanced perceived sound), unless you placed your boxe's rear at a wall/floor junction or even in the corner to get some "room gain" in the lows. BTW I NEVER scrap a good box unless it would be a lost cause, which is definitely NOT your case at all here...

I did run in Winspeakerz some new scenarios with an 8 cu. ft. box along with the revised E-145 Vas figure you mentioned of 427.7 L. or 15.1 cu. ft. (instead of JBL's 274.7 L. in T/S data table and 275 L. in E-series brochure). There is NO problem at all with your present 8 cu. ft. box volume (That's NET volume right? You did account (increase) that volume for space taken by drivers, bracing, etc. as I mentioned before?).

If you kept the tuning (Fb) at 45 hz, as suggested before the change in Vas, you will still get flat low-frequency response, F3 at 43 hz, but you'll have the E-145 rising response issue, also with the new Vas number. Box placement as mentioned above may help. Another easy way out is that you may add EQ in the 50-60 hz range for a small bump (1.5-2 db or so) to sort of balance low and mid levels perceived.

If box placement or EQ suggestions are not acceptable to you?, then you'll have to re-tune the box a little higher around 50-52 hz (not lower with longer ducted ports). The present vents MAY not be acceptable. Did you keep the circular vent cut-outs you got when you made cabinet holes for the vents? Please answer all my questions tonight or tomorrow morning so I can come back tomorrow with vent alternative vent suggestions, if need be. Gotta go now, I'll read you later. Regards,

Richard

[robertg]

Hi Robert,

Which Win ISD did you downloaded? ISD Beta or ISD Pro Alpha? WinISD 0.7.0.950. In Pro Alpha there is a sequence to follow when entering the data, otherwise that software bugs... In case you need that sequence let me know I have two of those. I did mention here or in another thread that different softwares lead to slightly different results. IF my memory is correct, ISD Pro uses QL 10 as default box loss assumption? I don't know where to find that? Verify that. While others use the usual QL 7 box loss assumption. This may make a small difference in cab volume/tuning. I think I was getting an error message, I thought it said division by zero or something like that, then it went away.

RE IVICA Post # 39

With all due respect for him, his thing doesn't make much sense in the present context because it means scrapping your present boxes and building new ones of 150L.(5.3 cu. ft.)! Plus your 2395 clones will probably not fit on that the way you wish. Finally, on the response curve he posted himself, the woofer's rising response that I mentioned previously (+2 db from about 200 hz at 1 watt) would become your worst nightmare at high sound levels: his curve shows at 50 hz about 118 db and at 250 hz or so about 125 db... With a now 7 db difference as level is increased, this thing is prone to huge mid-bassy sound which is unacceptable sound wise (poorly balanced perceived sound), unless you placed your boxe's rear at a wall/floor junction or even in the corner to get some "room gain" in the lows. BTW I NEVER scrap a good box unless it would be a lost cause, which is definitely NOT your case at all here...

I did run in Winspeakerz some new scenarios with an 8 cu. ft. box along with the revised E-145 Vas figure you mentioned of 427.7 L. or 15.1 cu. ft. (instead of JBL's 274.7 L. in T/S data table and 275 L. in E-series brochure). There is NO problem at all with your present 8 cu. ft. box volume (That's NET volume right? You did account (increase) that volume for space taken by drivers, bracing, etc. as I mentioned before?). Yes, net volume, should be really close to 8 cubic feet.

If you kept the tuning (Fb) at 45 hz, as suggested before the change in Vas, you will still get flat low-frequency response, F3 at 43 hz, but you'll have the E-145 rising response issue, also with the new Vas number. Box placement as mentioned above may help. Another easy way out is that you may add EQ in the 50-60 hz range for a small bump (1.5-2 db or so) to sort of balance low and mid levels perceived. I have a DBX Driverack PA2 crossover, so that isn't a problem.

If box placement or EQ suggestions are not acceptable to you?, then you'll have to re-tune the box a little higher around 50-52 hz (not lower with longer ducted ports). The present vents MAY not be acceptable. Did you keep the circular vent cut-outs you got when you made cabinet holes for the vents? I probably did, but new ones are easy to make. Please answer all my questions tonight or tomorrow morning so I can come back tomorrow with vent alternative vent suggestions, if need be. Gotta go now, I'll read you later. Regards,

Richard

When I enter in 45 Hz as my tuning frequency and 226 l, it wants a vent length of 8.56 cm. The graph that comes up crosses the -2 line at 50, rises a bit then hits -2 again between 72 and 88. It then gradually rises and hits 0 at 400.

[RMC]

Hi Robert,

The Win ISD version number you're giving me doesn't correspond to both of my versions: ISD Beta v. 0.44 dated 15 Jan. 2002 and ISD Pro Alpha v. 0.50a7 dated 11 Sept. 2004. You downloaded the latest version issued 29 Oct. 2016, which I just downloaded and haven't had time to try and test. I've been using more Winspeakerz lately since I like it and paid for it...

In the older versions I used when you opened a project in the "Box" Tab at bottom left there's an "Advanced" mention that can be clicked-on and shows for rear chamber the boxe's QL, Qa, Qp numbers used, plus these can be changed manually if you clicked on the QL number for example another box opened and you can write 7 instead of 10 or vice versa.

You mention a 45 hz tuning frequency with flat low-end response (and rising mid-bass response) isn't a problem for you because of your Driverack x-over, then it means you can add, as required, a few db in the 50-60 hz range easily. That would be an easy way out on the issue of balancing low and mid woofer levels.

You may not be required to re-tune the boxes if you are satisfied with the present boxe's sound with the lows processed by the Driverack. The idea of keeping the cut-outs made is if a re-tuning is a must then they can be reused, glued back in their place to cover vents # 1 and 3, to plug the existing vent holes, wood filler (plastic wood) on the outside, silicone on the inside remaining cutting line, then glueing/screwing a small piece of plywood (3/8"- 1/2" thick) on the inside to cover where the previous hole was and a little more, as this gives more rigidity to the repair. If a larger vent is ever required the center hole (vent # 2) can be used as a starting point in the free space between vents 1 and 3 that are plugged.

Finally, as for a vent of 8.56 cm long from the software, I haven't tried it yet so I'll have to come back on this.

Richard

[ivica]

Hi Robert,


RE IVICA Post # 39

With all due respect for him, his thing doesn't make much sense in the present context because it means scrapping your present boxes and building new ones of 150L.(5.3 cu. ft.)! Plus your 2395 clones will probably not fit on that the way you wish. Finally, on the response curve he posted himself, the woofer's rising response that I mentioned previously (+2 db from about 200 hz at 1 watt) would become your worst nightmare at high sound levels: his curve shows at 50 hz about 118 db and at 250 hz or so about 125 db... With a now 7 db difference as level is increased, this thing is prone to huge mid-bassy sound which is unacceptable sound wise (poorly balanced perceived sound), unless you placed your boxe's rear at a wall/floor junction or even in the corner to get some "room gain" in the lows. BTW I NEVER scrap a good box unless it would be a lost cause, which is definitely NOT your case at all here...

Richard

When I enter in 45 Hz as my tuning frequency and 226 l, it wants a vent length of 8.56 cm. The graph that comes up crosses the -2 line at 50, rises a bit then hits -2 again between 72 and 88. It then gradually rises and hits 0 at 400.

Hi,

the difference in the F/R response would not change much changing from 150 lit to 225 lit, but adding about 2 ohm resistor 'in-line' with the driver would reduce mid-bass rising in the response...

regards
ivica