Hello group,
sorry for the late involvement. I have only now discovered this thread.
I think Andrea has explained himself very well regarding his requirements. However we must rate and priorities features and technical requirements. We are researchers and scientists, are we not? We must make compromises but they also must be correctly calculated.
Anyway, A good 15" needs a big box. Then, most that I have heard don't come alive soon. Explanation: most PA drivers are designed to be efficient but to also handle an enormous quantity of power (700W, 1500W etc...). This, in my opinion, is ridiculous. We are only dealing with 4 Watts amp power. This power handling, from that I have noticed, doesn't allow the driver to "open" soon (or at low power). You need to really push it with more power to make it extend. I'm not sure why or how but I am sure someone here has this theoretical knowledge. This is resolved by using "vintage" (Alnico) drivers. They are fast, efficient and work well in small (or no boxes). They are also very expensive.
Could a better solution to use two 12" be better? How would this work?
My instinct would not be to make a bass woofer enter past 400hz... wouldn't there be cone break up? Producing 40hz while producing 600hz would be very difficult. Someone here has said that even with the horn extended to 400hz there are other problems. Can these be remedied?
Cheers,
MV
sorry for the late involvement. I have only now discovered this thread.
I think Andrea has explained himself very well regarding his requirements. However we must rate and priorities features and technical requirements. We are researchers and scientists, are we not? We must make compromises but they also must be correctly calculated.
Anyway, A good 15" needs a big box. Then, most that I have heard don't come alive soon. Explanation: most PA drivers are designed to be efficient but to also handle an enormous quantity of power (700W, 1500W etc...). This, in my opinion, is ridiculous. We are only dealing with 4 Watts amp power. This power handling, from that I have noticed, doesn't allow the driver to "open" soon (or at low power). You need to really push it with more power to make it extend. I'm not sure why or how but I am sure someone here has this theoretical knowledge. This is resolved by using "vintage" (Alnico) drivers. They are fast, efficient and work well in small (or no boxes). They are also very expensive.
Could a better solution to use two 12" be better? How would this work?
My instinct would not be to make a bass woofer enter past 400hz... wouldn't there be cone break up? Producing 40hz while producing 600hz would be very difficult. Someone here has said that even with the horn extended to 400hz there are other problems. Can these be remedied?
Cheers,
MV
I've noticed that most of these drivers have an artificial (not paper) cone! I have never heard an acceptable sounding speaker with a plastic cone. If it is in the mid range you should avoid non paper drivers. The plastic cones, IMO, are effective at moving the air around (deep bass production), not for timber or to reproduce natural realistic sound.
I would consider to use only paper cones for this project since the extension is to 800hz and the plastic will be very "plastically" sounding and very audible.
If you don't agree please tell me (or send me) a plastic cone driver that sounds good.
Graphs are not everything. It is better to take a group of similar drivers and test them in the same enclosure until you have found the right synergy.
I would consider to use only paper cones for this project since the extension is to 800hz and the plastic will be very "plastically" sounding and very audible.
If you don't agree please tell me (or send me) a plastic cone driver that sounds good.
Graphs are not everything. It is better to take a group of similar drivers and test them in the same enclosure until you have found the right synergy.
Thank you for your suggestion.
I see you love paper cone but what you think about fiber glass and kevlar and carbon.
In some case this is true, many people love the first version of Proac louspeakers because this use normal Scan Speak paper cone and not new cones with kevlar, PP or cabon.
As first test I will try to use the Celestion FTR15-3070C that is a glass fibre impregnated cones and these should be on the way.
I see you love paper cone but what you think about fiber glass and kevlar and carbon.
In some case this is true, many people love the first version of Proac louspeakers because this use normal Scan Speak paper cone and not new cones with kevlar, PP or cabon.
As first test I will try to use the Celestion FTR15-3070C that is a glass fibre impregnated cones and these should be on the way.
I have considered in the simulation for the Celestion woofer the Mmd and not the Mmt, this is an error
I need to recalculate the volume and box design.
----- Original Message -----
From: celestion
To: Ciuffoli Andrea
Sent: Thursday, April 16, 2009 1:47 PM
Subject: RE: info
You should use Mmt which is Mmd + Mair.
Regards
The Doc
I need to recalculate the volume and box design.
----- Original Message -----
From: celestion
To: Ciuffoli Andrea
Sent: Thursday, April 16, 2009 1:47 PM
Subject: RE: info
You should use Mmt which is Mmd + Mair.
Regards
The Doc
Hi Andrea,
with the PA 15", in my own experience, you need to give them enough power. Though they are >96spl doesn't mean they will sound good with low power.
Ex. 15" JBLs are a fantastic but you need to give them at least 20 class A watts to wake them up! My SETs did not work! ;( The PP 6550 I borrowed was much better.
Please let me know about your discoveries and i hope we can discover something new!
Can I ask why you didn't decide to use the 400hz horn?
Cheers,
MV
Ps. I have seen your site. Very interesting projects.
with the PA 15", in my own experience, you need to give them enough power. Though they are >96spl doesn't mean they will sound good with low power.
Ex. 15" JBLs are a fantastic but you need to give them at least 20 class A watts to wake them up! My SETs did not work! ;( The PP 6550 I borrowed was much better.
Please let me know about your discoveries and i hope we can discover something new!
Can I ask why you didn't decide to use the 400hz horn?
Cheers,
MV
Ps. I have seen your site. Very interesting projects.
About // or series 12":
I think it could be possible to try 16ohm in parallel or series connect 12".
About paper v. other materials:
Anyway, I would stay away of anything but paper cones. Have you been to a concert recently? The sound I find horrible when long ago it was pleasurable. Now I just want to leave.
Maybe for marketing reasons people want millions of watts and make decisions only based on this; how much air we can move and how much noise we can make? The plastic and kevlar cones are much more durable for these applications but you must compromise sound quality. And yes I used to use the Etons quite often in the 90s.
I recommend a large test box for now 300l where you can modify volume and vent size. Too bad we are not close.
Cheers and good luck!
I think it could be possible to try 16ohm in parallel or series connect 12".
About paper v. other materials:
Anyway, I would stay away of anything but paper cones. Have you been to a concert recently? The sound I find horrible when long ago it was pleasurable. Now I just want to leave.
Maybe for marketing reasons people want millions of watts and make decisions only based on this; how much air we can move and how much noise we can make? The plastic and kevlar cones are much more durable for these applications but you must compromise sound quality. And yes I used to use the Etons quite often in the 90s.
I recommend a large test box for now 300l where you can modify volume and vent size. Too bad we are not close.
Cheers and good luck!
Andrea,
Someone should have mentioned this before.. but an "aligned" response is usually all wrong.
In particular, (on the lower freq. end), you have room-gain and baffle step compensation to factor in. (..Higher in freq. you are likely to have floor bounce issues with a 15" driver.. depending on how close it is to the floor and if the baffle has significant angle departure from vertical.)
As far as the lower freq. response is concerned:
Depending on the baffle - most baffles will need between 3-5 db of compensation at 100 Hz. However.. rooms (depending on the shape, construction, losses, etc.), often have about 1-2 db of gain 100 Hz. The "average" net then is typically about 2-3 db of baffle step reduction at 100 Hz. Progressively greater reduction at higher freq.s, less at lower freq.s.
With an aligned response AND baffle step compensation the lower freq.s (below 100 Hz) become increasingly elevated above the average. This (in combination with extended group delay from the port's contribution), usually leads to "bloated" bass. It gets even worse if you factor-in a tube amplifier's gain from the reaction to the impedance swing.
The "funny" thing is IF you factor-in all of the above.. the Monacor SP38 in a *sealed* enclosure slightly LESS than the design you had for the Celestion.. with baffle step compensation SHOULD give you something similar to what you targeted with the Celestion.
Here is Martin Colloms "average" room-gain guesstimate:
http://www.diyaudio.com/forums/attachment.php?s=&postid=88719&stamp=1038551652
Here is the Edge to work with baffle step loss (& compensation):
http://www.tolvan.com/edge/
TIP: ..look to Erse for cheap but decent large value capacitors (..and of course by-pass with something better).
Someone should have mentioned this before.. but an "aligned" response is usually all wrong.
In particular, (on the lower freq. end), you have room-gain and baffle step compensation to factor in. (..Higher in freq. you are likely to have floor bounce issues with a 15" driver.. depending on how close it is to the floor and if the baffle has significant angle departure from vertical.)
As far as the lower freq. response is concerned:
Depending on the baffle - most baffles will need between 3-5 db of compensation at 100 Hz. However.. rooms (depending on the shape, construction, losses, etc.), often have about 1-2 db of gain 100 Hz. The "average" net then is typically about 2-3 db of baffle step reduction at 100 Hz. Progressively greater reduction at higher freq.s, less at lower freq.s.
With an aligned response AND baffle step compensation the lower freq.s (below 100 Hz) become increasingly elevated above the average. This (in combination with extended group delay from the port's contribution), usually leads to "bloated" bass. It gets even worse if you factor-in a tube amplifier's gain from the reaction to the impedance swing.
The "funny" thing is IF you factor-in all of the above.. the Monacor SP38 in a *sealed* enclosure slightly LESS than the design you had for the Celestion.. with baffle step compensation SHOULD give you something similar to what you targeted with the Celestion.
Here is Martin Colloms "average" room-gain guesstimate:
http://www.diyaudio.com/forums/attachment.php?s=&postid=88719&stamp=1038551652
Here is the Edge to work with baffle step loss (& compensation):
http://www.tolvan.com/edge/
TIP: ..look to Erse for cheap but decent large value capacitors (..and of course by-pass with something better).
I find this driver interesting: Etone 1525. It's made in Australia and sold for AUD109. I've got two of them currently under testing and evaluation. On software simulation I compared it with many drivers and I have to say it's not bad and hard to find a better one in the LF for the buck.
Here the parameters:
FS=27.155 (28.2 measured myself out of the box)
Sd=855
Voice Coil diam=63mm
Re=6.1R
Qms=14.039
Qes=0.329
Qts=0.322
BL=14.1 T.M.
Vas=564.099l
SPL=97.2dB
Mms=63.259g
Md=95g
Le=??????? waiting from the manufacturer so I don't know about the top end yet
Please give me your opinion on simulation.
Thanks
Alfonso
Here the parameters:
FS=27.155 (28.2 measured myself out of the box)
Sd=855
Voice Coil diam=63mm
Re=6.1R
Qms=14.039
Qes=0.329
Qts=0.322
BL=14.1 T.M.
Vas=564.099l
SPL=97.2dB
Mms=63.259g
Md=95g
Le=??????? waiting from the manufacturer so I don't know about the top end yet
Please give me your opinion on simulation.
Thanks
Alfonso
Ciao Andrea,
Sorry the chart is not available and I asked the manufacturer why is not available. Well he said "it is hard to make one that can be true and accurate". He's got another lab in Tasmania, I'll probably ask him to provide one from the lab. In the meantime I will build the box and I'll do some "hearing" tests. If it's good I will rather spend money on a pair of TPL150H. I can provide some pictures if you like. The manufacturer mentioned that he worked a lot around the design of the gap in the coil. I'm not sure what it means to you.
Guess what, I'm also using the KT88 PP no feedback you designed
Thanks,
Alfonso
Sorry the chart is not available and I asked the manufacturer why is not available. Well he said "it is hard to make one that can be true and accurate". He's got another lab in Tasmania, I'll probably ask him to provide one from the lab. In the meantime I will build the box and I'll do some "hearing" tests. If it's good I will rather spend money on a pair of TPL150H. I can provide some pictures if you like. The manufacturer mentioned that he worked a lot around the design of the gap in the coil. I'm not sure what it means to you.
Guess what, I'm also using the KT88 PP no feedback you designed
Thanks,
Alfonso
The manufacturer is very friendly and he is able to build a custom one starting from 1525 base. One thing I find in common with all 15" I tried: there are chaotic waves in the high part of the frequency spectrum coming out of the centre coil under the dust cap. I will try to design a phase plug for this driver and the manufacturer will prepare a new one without the dust cap.
Nice speaker and price.
Only BR 280liter 40Hz 97dB very big
Best option closed. 100liter 63Hz 97dB Q=0,8 reasonable size.
Or 4th order bandpass 175liter 40-126hz 95dB Q=0,8. Nice low and good XO point.
High QMS sound better was a topic lately then this driver sounds superb. QMS=14
Regards Helmuth
Only BR 280liter 40Hz 97dB very big
Best option closed. 100liter 63Hz 97dB Q=0,8 reasonable size.
Or 4th order bandpass 175liter 40-126hz 95dB Q=0,8. Nice low and good XO point.
High QMS sound better was a topic lately then this driver sounds superb. QMS=14
Regards Helmuth
Attachments
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.