"Houston we have a problem" Isobarik Sub
I hope some one can answer this for me I am building a Isobarik sub using 2 Dayton Part # 295-185 dual VC sub. I thought I found a real good deal on 4 of these so I bought them. I was using Bass Box 6 for design and thought I had a real winner OPPS
I made a big mistake I did not see bass box had set up as individual VC instead of parallel VC. At first I thought nothing of it untill my I reset Bass Box and seen my F3 went from 28 Hz to 52 HZ. I am a bit of a newbie at this home DIY, I have done many car subs just using the air space for the box for a sealed box and all was good. So what has happened here when I reset and started over the suggested air space went down to .64 from 1.489 😕 Why would my Vb get cut 60% just by changing VC wiring to match the ohms for the amp I want to use? I can't see any way to use individual VC's in a isobarik sub but now I own 4 of these subs and really don't want to build a single sealed box that I have done a bunch of times before. Is there any way to get this sub to to flatten its response, or am I wrong to think this is a problem at all?
I hope some one can answer this for me I am building a Isobarik sub using 2 Dayton Part # 295-185 dual VC sub. I thought I found a real good deal on 4 of these so I bought them. I was using Bass Box 6 for design and thought I had a real winner OPPS
I made a big mistake I did not see bass box had set up as individual VC instead of parallel VC. At first I thought nothing of it untill my I reset Bass Box and seen my F3 went from 28 Hz to 52 HZ. I am a bit of a newbie at this home DIY, I have done many car subs just using the air space for the box for a sealed box and all was good. So what has happened here when I reset and started over the suggested air space went down to .64 from 1.489 😕 Why would my Vb get cut 60% just by changing VC wiring to match the ohms for the amp I want to use? I can't see any way to use individual VC's in a isobarik sub but now I own 4 of these subs and really don't want to build a single sealed box that I have done a bunch of times before. Is there any way to get this sub to to flatten its response, or am I wrong to think this is a problem at all?Ignore the individual wiring option in bassbox, it appears to plot the response you would get with only one voice coil connected, unless of course you prefer that response and can deal with halving the power handling of the drivers.
I see what your saying but but this explains very little as to why I am losing 8.5 DB @ 29 Hz when before I only lost 3 Db at 29 Hz. I have tried every possible combination of VC's but only individual seems to have a good response and that seems a bit crazy. I also see a great amount of system impedance increase between 60 hz and 30 hz and this seems to go with my loss of low bass response. I would think one VC would carry all the load causing the coil to heat then 2 VC's would split the load and heat less? The other thing I don't get is why should my Box Vb change no matter what VC combination I would use?
hmmm...
I'm going to re-test a dual voice coil sub I have here using just one voice coil to see if the change in Qes and Qts is comparable to what we see in that dayton sub...
I'm going to re-test a dual voice coil sub I have here using just one voice coil to see if the change in Qes and Qts is comparable to what we see in that dayton sub...
My test results are consistant with the change in the Dayton parameters and the subsequent change in system response.
ahh I see where you are seeing the large difference, you're using normalized Amplitude response, which I've found to be pretty useless, use Custom Amplitude response, and you'll see there's far less difference between the different configurations when compared with the same power input.
ahh I see where you are seeing the large difference, you're using normalized Amplitude response, which I've found to be pretty useless, use Custom Amplitude response, and you'll see there's far less difference between the different configurations when compared with the same power input.
Then if all the data here is correct then I must conclude that this sub just does not perform well in sub frequency range in a closed box or at least using both VC's as a compound isobaric sub, because even while the graph looks better the actual numbers still look bad. I still see a loss of at least 8.5 Db at 30 Hz. Was your data also constant with the Vb. being .64 Cf. for the dual VC’s and 1.489 Cf. for the single VC? I did test parameter changes and box configurations last night till my eyes bleed. Nothing I did helped, I did different Isobaric configurations mag. to mag. and facing the same direction, round isobaric chamber and square and all still seems to be the same only the single VC works well. Even this came at cost gaining so much Vb. I ended up with a 24.75” long and a 14.25 X 14.25 W/H. I can get the size down some with a round isobaric chamber but then the cabinet work get more difficult using sono tube for the isobaric chamber. I just was hoping I could get a good test box with little work as this was intended for final use in the bottom of a pair of bi-amped loudspeakers. I really am grateful for your help in this matter. I am just bit beside myself yet with this. Do you think some real world test could be fruitful?
You need to up the enclosure size of the simulation with both coils to the same size as single coil. This will probably change the response significantly. As much as 8db at 30hz I'd guess
Do you need an enclosure that small? You know you'll get some room gain.
If the response isn't good enough, you could port your isobaric box or use a passive radiator.
If the response isn't good enough, you could port your isobaric box or use a passive radiator.
BassAwdyO
I just tried to increase my Vb to the same as a single VC and still my frequency response remains almost the same, I have a 3 Db drop at 51 Hz and no matter the size of the box the response remains the same right down to the point the driver will no longer fit the box Vb .64 and then I went all the way up to Vb 2.5 and the same thing. I even tried to increase and decrease The Isobaric chamber Vb and still nothing changes. Change the set up for single VC and abracadabra the frequency response flattens out and I am not getting a 3Db drop until 29 Hz and everything looks great. Well all most great because then I just cut my power handling from 1200 watts to 600 Watts. Opps and one more thing it just don't make any sense!!! If I did not buy these Daytons already would have looked for a single VC sub and saved you all from my crazy questions *LOL*
I just tried to increase my Vb to the same as a single VC and still my frequency response remains almost the same, I have a 3 Db drop at 51 Hz and no matter the size of the box the response remains the same right down to the point the driver will no longer fit the box Vb .64 and then I went all the way up to Vb 2.5 and the same thing. I even tried to increase and decrease The Isobaric chamber Vb and still nothing changes. Change the set up for single VC and abracadabra the frequency response flattens out and I am not getting a 3Db drop until 29 Hz and everything looks great. Well all most great because then I just cut my power handling from 1200 watts to 600 Watts. Opps and one more thing it just don't make any sense!!! If I did not buy these Daytons already would have looked for a single VC sub and saved you all from my crazy questions *LOL*
Fearlessleader1 said:
With that thought in mind I used the same DVC sub I tested earlier in both individual and paralell with some music I know well, I used the same 50L test box that I have for testing driver parameters.
I did notice a difference between the two configurations that was consistant with the model in Bassbox.
I would suggest a real world test would indeed help you a great deal in deciding on what configuration would be most suitable for you.
simon5
I don’t need to have box smaller then Vb 1.5 it would really be better then the VB .64 because @ a Vb of 1.5 I would end up with a bottom box as a base of 16.5 X 14.25 X 21.25 which should be pretty close to work with to make a stuffed pipe transmission line with a 7” or 8” driver on top as my next stage. As a said before I am working on a bi-amped flool standing Loudspeaker and have to keep my box sizes with in reason so I don't end up with a 10' high tower in my livingroom. My wife is pretty cool about this stuff but I think that would get me on the couch!!*LOL*
I don’t need to have box smaller then Vb 1.5 it would really be better then the VB .64 because @ a Vb of 1.5 I would end up with a bottom box as a base of 16.5 X 14.25 X 21.25 which should be pretty close to work with to make a stuffed pipe transmission line with a 7” or 8” driver on top as my next stage. As a said before I am working on a bi-amped flool standing Loudspeaker and have to keep my box sizes with in reason so I don't end up with a 10' high tower in my livingroom. My wife is pretty cool about this stuff but I think that would get me on the couch!!*LOL*
If you can make it 1.5 cu.ft with a base of 16.5 X 14.25 X 21.25, to get a flatter frequency response, you could port the isobaric enclosure.
You could port it with a single FP3 vent (18 inches long), which would sit parallel with the 21.25 inches side.
You wouldn't have noise problems under 300W imput to the isobaric pair.
What amplifiers are you planning to use?
Please use woofer to woofer if you go isobaric. The other configurations aren't very good. Magnet out isn't that pretty but it's the way it should be done.
Here's the FR curve at 300W ported vs. sealed for your 1.5 cu.ft enclosure.
I optimized the tuning of the ported enclosure to give flat response down to a in-room F3 of about 22-23 Hz.
You could port it with a single FP3 vent (18 inches long), which would sit parallel with the 21.25 inches side.
You wouldn't have noise problems under 300W imput to the isobaric pair.
What amplifiers are you planning to use?
Please use woofer to woofer if you go isobaric. The other configurations aren't very good. Magnet out isn't that pretty but it's the way it should be done.
Here's the FR curve at 300W ported vs. sealed for your 1.5 cu.ft enclosure.
I optimized the tuning of the ported enclosure to give flat response down to a in-room F3 of about 22-23 Hz.
Attachments
BTW, if you got some money left, the proper way to do it to be able to use more than 300W without noise would be to use passive radiators.
Acoustic Elegance got some on sale at 45$ each.
Acoustic Elegance got some on sale at 45$ each.
simon5
I am trying to take in all you have suggested but it just a bit much, as I have had my head set on a close box with both speakers facing the same direction. The mag to mag push-pull again made the box to large because the isobaric chamber Vb, but was my first choice. The thought of a clam shell was never on my mind, but then you may have a very good point. The one thing about that idea that sets me back is, I would not have any idea how to make it look good with the sub hanging out the back of my towers. I have never been a fan of any other type of box beside a close type for the last 20 years every car I owned had sealed box 10” drivers so I was just trying to put a bit of a spin and something I know works by using the sealed isobaric sub. I seen lots of ported boxes at the sound competitions for that SPL but never heard nothing I liked, they just get sloppy when you put to much power to them but not to put them down they do give up some really great SPL with much less power and I just assumed that good bass comes at a cost with no compromise. I also realize I have not heard everything and don’t know everything. I will just say this, my best hope for this project is to have tight bass with a very flat response and I will be willing to learn what ever the great people in the group are willing to teach Me.! I am going to try to look more at your ideas. I may need a bit more time to digest it as I know nothing about ported or passive type design and have not studied them to any extent. I have been studying about transmission line design, as for my decision to use that for my next step woofer.
Now as for the Amps I will be using I am currently looking to purchase 2 Adcom GFA-565 Mono Blocks to drive the subs I am currently using an Adcom GFA-585, also I may decide to go tri-amped and add a GFA-545 to drive my tweeters. I am a big fan of Adcom amps!!!!!! I am also looking for a good active crossover to put this whole thing together.
I am trying to take in all you have suggested but it just a bit much, as I have had my head set on a close box with both speakers facing the same direction. The mag to mag push-pull again made the box to large because the isobaric chamber Vb, but was my first choice. The thought of a clam shell was never on my mind, but then you may have a very good point. The one thing about that idea that sets me back is, I would not have any idea how to make it look good with the sub hanging out the back of my towers. I have never been a fan of any other type of box beside a close type for the last 20 years every car I owned had sealed box 10” drivers so I was just trying to put a bit of a spin and something I know works by using the sealed isobaric sub. I seen lots of ported boxes at the sound competitions for that SPL but never heard nothing I liked, they just get sloppy when you put to much power to them but not to put them down they do give up some really great SPL with much less power and I just assumed that good bass comes at a cost with no compromise. I also realize I have not heard everything and don’t know everything. I will just say this, my best hope for this project is to have tight bass with a very flat response and I will be willing to learn what ever the great people in the group are willing to teach Me.! I am going to try to look more at your ideas. I may need a bit more time to digest it as I know nothing about ported or passive type design and have not studied them to any extent. I have been studying about transmission line design, as for my decision to use that for my next step woofer.
Now as for the Amps I will be using I am currently looking to purchase 2 Adcom GFA-565 Mono Blocks to drive the subs I am currently using an Adcom GFA-585, also I may decide to go tri-amped and add a GFA-545 to drive my tweeters. I am a big fan of Adcom amps!!!!!! I am also looking for a good active crossover to put this whole thing together.
simon5
Now you have really got me curious
What the the thing with noise with a sealed box over 300 watts I have 1000 watts driving 2 10" subs in my car and they sound tight and clean. I have seen somthing about this in other threads hear too
simon5 said:
Now you have really got me curious
What the the thing with noise with a sealed box over 300 watts I have 1000 watts driving 2 10" subs in my car and they sound tight and clean. I have seen somthing about this in other threads hear tooVolenti said:
I am thought that it would help,plus it may help me learn a bit more too. All the formulas and program simulations are fine but lack a fun factor! I think I will just set up my first box using the single Vc’s because that box could also work for some of the ideas (simon5) has presented to me with.
Thanks again for your help with all the data verification
You would have a noise problems if you go ported with my suggestion and you use more than 300W. You'll have vent noise. Air is going too fast in the vent.
With passive radiators, the box is closed, so no vent noises.
Clamshell isobaric with passive radiator, that would be interesting hehe!
With passive radiators, the box is closed, so no vent noises.
Clamshell isobaric with passive radiator, that would be interesting hehe!
The test
I have completed some tests regarding sealed, ported and passive radiator and I am thinking know at this point I have come down to using one of 2 and I was able to make one box size to real world test both. I can make one internal size box @ 12.5 X 12.5 X 17.8 box to do my testing as this should be a good base size the loudspeakers I intend to build them into. It would seem that the seal individual VC box will be my first choice and the then PR. I just need a bit more help as to how to place my drivers, down firing front, side or whatever also the best placement for the PR’s ? I would like any input that you all may have on which the PR or the SB would be most effective to make good tight bass. These will be used mostly for Rock type music and secondly for the subs for my home theater. Home theater would be least important. Here are my last simulations.
Thanks
I have completed some tests regarding sealed, ported and passive radiator and I am thinking know at this point I have come down to using one of 2 and I was able to make one box size to real world test both. I can make one internal size box @ 12.5 X 12.5 X 17.8 box to do my testing as this should be a good base size the loudspeakers I intend to build them into. It would seem that the seal individual VC box will be my first choice and the then PR. I just need a bit more help as to how to place my drivers, down firing front, side or whatever also the best placement for the PR’s ? I would like any input that you all may have on which the PR or the SB would be most effective to make good tight bass. These will be used mostly for Rock type music and secondly for the subs for my home theater. Home theater would be least important. Here are my last simulations.
Thanks
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