Carlos Beltran
Auditioning
- Joined
- Jan 9, 2005
- Messages
- 3
Greetings,
I am back. Many of you have emailed me and encouraged me to come back and speak up for the Acoupower drivers. This is a long message, and it answers many questions and comments concerning our sub drivers. I will place the same message on a few forums.
I do have one favor to ask first: I am troubled by so many negative comments coming from people who have not even tried our drivers. PLEASE hold off your negative comments until you personally gain some practical experience with our drivers- then slam them all you want. These drivers are different enough that they demand a fair examination before giving them a bad rap. All I can say is nobody has complained once receiving them. I have always taken great pride throughout my career in making my customers truly happy. Please give Acoupower an OPPORTUNITY do make an impression before you slam our products just because to can.
First of all, we have heard your requests for data. t-s parameters of our -01 drivers are already on these forums, and will be put on the web site shortly. Keep in mind we have other variations of our drivers available, and we will be posting this data as well. We are accumulating performance data in different boxes and will post some of it on the site soon. We do have some measurements now that I am willing to give out. Just email me directly.
After reviewing my own words on these forums, and those of a few others, I need to clarify where Acoupower is coming from with it's products. Our audio drivers are primarily designed for high end home and professional sound applications, where they may be used to a few hundred Hz, and where distortion is of paramount importance. In professional audio applications, they will be driven very hard for several hours at a time.
O.K., now that you know where we are coming from, lets look at WHY we did what we did.
The voice coil is a low inductance 2 layer 6" diameter coil with every inch of wire facing steel. Between the wire and the steel is a high velocity air flow. This high velocity air is rapidly exchanged with air around, and behind the driver. In addition, the steel is cooled VERY aggressively. On the outside is the largest heat sink ever seen on a speaker- approximately 5 sq. ft. of surface area, 80% of which has high velocity air flowing through it. Deep inside the speaker is an aluminum cup that maintains a very rapidly moving channel of air over the entire inside surface of our enormous "top pot". This air is ejected out of the back of the speaker through a 1.5" diameter hole in the center of the motor structure at enormous velocity. This is one of the primary features covered carefully in our patent application. As a result, our drivers exhibit NO audible power compression when used all but the very largest amplifiers made. This is not an overstatement. The more experience we have with our drivers, the more testing we do, and the more feedback we get from customers, the more we are convinced of this. To demonstrate this another way, our drivers will remain at temperatures only slightly above ambient, even after several hours of being driven at 1,000W RMS. I am unaware of any other off the shelf driver whose motor structure is only slightly warm after several hours of 1,000 Watts RMS. The long term AES rating of our drivers is 2-3.5kW, depending on the application. The true long term power handing (hours) of a driver is dependent on the driver's ability to dissipate it's thermal energy rapidly and efficiently to the surrounding air. Acoupower's drivers excel at this. This is why our long term power handling is 2-6 times that of current high performance drivers.
We also use a full length copper shorting sleeve. Why use a full length copper shorting sleeve when we are only using a relatively low inductance 2L coil to begin with? Because a full length copper shorting sleeve is the one thing that can be relatively easily implemented that is guaranteed to significantly reduce motor based distortion caused by the coil’s magnetic field. Why not lower the distortion even more if it doesn’t cost much to do? I have been designing speakers and transducers for more than 25 years- this is a “no brainer” if you are making a high performance (low distortion) product. I am sorry to disappoint some of you who thought we had to have the sleeve in there to offset some problem in the design. ONCE AGAIN, PLEASE EVALUATE our products before blasting them. Even without the sleeve, the distortion is low. With it- even lower. BTW, I have an impedance curves of our drivers I would be happy to email anyone. The impedance of our drivers is amazingly flat for a driver of this size.
There has been a lot of comparisons made of our drivers to drivers meant for car use. While we have customers who have put our drivers in cars and are in love, our drivers were not designed for car use (in case the 8 ohm ONLY impedance did not make that point clear on it’s own). For more than six months now, our web site has stated that we do NOT recommend the use of these drivers in ANY confined space, including cars. This is the position we have taken based on the actual capabilities of our drivers and the liability inherent in placing such high output devices in any confined space. Moving on. Car drivers are very different animals. Sub drivers for car use are designed for ENORMOUS power capability for the short term. Nobody cares how much power they take for hours at a time. Car audio sub drivers have extremely heavy voice coils. No doubt about it, these heavy coils can take enormous power levels for short periods of time (many seconds) due simply to their thermal mass. These heavy coils are the primary reason that car subs have low efficiency, NOT to be confused with sensitivity, which can easily be made high by lowering DCR. These heavy coils also have large inductances and generate large amounts of distortion through their interaction with the motor structures. Lastly, the high mass and high inductance of these coils results in a response that drops after 80-100 Hz. In fact, the high inductance in the coil tends to give the typical car sub box a boost in the 60-80Hz range. There is nothing wrong with that for a car, but for high end home or pro-audio use, that is a problem. BTW, Acoupower’s sub drivers also handle unbelievable short term power, due not to their huge weight, but because ALL of the wire is in close proximately to steel and a rapidly moving air flow.
Recapping, Acoupower’s sub drivers feature the following attributes:
1) Very smooth response to several hundred Hz. The -01 15” in particular is flat +-1dB to 500Hz.
2) Reasonably good Sensitivity and very good Efficiency for a very high output and very long throw driver.
3) Very low distortion, even at very high drive levels (this is, by far, the attribute that has been most commented on by our customers).
4) Incredibly high short and long term long term power handling.
5) Inherently shielded motor design.
Acoupower’s 18” vs. 15”. I have received some emails about the parameter differences between the 15” and 18” -01 designs. The 15” units are primarily aimed at high end home audio and high end home theater. The 18” units are primarily aimed at the high end pro-audio market. The -01 15” units work great in sealed and vented boxes and yield awesome response characteristics down to very low frequencies. The 18” are primarily engineered for MAX SPL pro-audio applications which rarely go below 30Hz. They are best implementation in multi-chamber bandpass boxes where the excursions for a given drive voltage are much less throughout a reasonable bandwidth. In such applications, two of our -01 18” drivers can yield SUSTAINED RMS 1m levels of 140dB +-3dB from 30Hz to 100Hz from a single box no more than 20 cu. Ft. in size. Needless to say, along with some pro-audio system manufacturers, we are in the process of re-defining the standard “club” box. Most club boxes had very high output in the 60-100Hz range, but the average response from 30Hz to 60Hz is typically some 6dB less. The +-3dB specs often published here is REALLY pushing the limit on reasonable specifications. Our drivers enable equal size boxes to be built with much higher output in the lower octave while maintaining the output at higher frequencies. In short, a lot more thump, and along with it, lower distortion.
Lastly, our web site is being updated regularly. We will post very nice looking 3-D exploded views of our drivers later this week.
Well, that is enough for now.
Ciao,
Carlos
I am back. Many of you have emailed me and encouraged me to come back and speak up for the Acoupower drivers. This is a long message, and it answers many questions and comments concerning our sub drivers. I will place the same message on a few forums.
I do have one favor to ask first: I am troubled by so many negative comments coming from people who have not even tried our drivers. PLEASE hold off your negative comments until you personally gain some practical experience with our drivers- then slam them all you want. These drivers are different enough that they demand a fair examination before giving them a bad rap. All I can say is nobody has complained once receiving them. I have always taken great pride throughout my career in making my customers truly happy. Please give Acoupower an OPPORTUNITY do make an impression before you slam our products just because to can.
First of all, we have heard your requests for data. t-s parameters of our -01 drivers are already on these forums, and will be put on the web site shortly. Keep in mind we have other variations of our drivers available, and we will be posting this data as well. We are accumulating performance data in different boxes and will post some of it on the site soon. We do have some measurements now that I am willing to give out. Just email me directly.
After reviewing my own words on these forums, and those of a few others, I need to clarify where Acoupower is coming from with it's products. Our audio drivers are primarily designed for high end home and professional sound applications, where they may be used to a few hundred Hz, and where distortion is of paramount importance. In professional audio applications, they will be driven very hard for several hours at a time.
O.K., now that you know where we are coming from, lets look at WHY we did what we did.
The voice coil is a low inductance 2 layer 6" diameter coil with every inch of wire facing steel. Between the wire and the steel is a high velocity air flow. This high velocity air is rapidly exchanged with air around, and behind the driver. In addition, the steel is cooled VERY aggressively. On the outside is the largest heat sink ever seen on a speaker- approximately 5 sq. ft. of surface area, 80% of which has high velocity air flowing through it. Deep inside the speaker is an aluminum cup that maintains a very rapidly moving channel of air over the entire inside surface of our enormous "top pot". This air is ejected out of the back of the speaker through a 1.5" diameter hole in the center of the motor structure at enormous velocity. This is one of the primary features covered carefully in our patent application. As a result, our drivers exhibit NO audible power compression when used all but the very largest amplifiers made. This is not an overstatement. The more experience we have with our drivers, the more testing we do, and the more feedback we get from customers, the more we are convinced of this. To demonstrate this another way, our drivers will remain at temperatures only slightly above ambient, even after several hours of being driven at 1,000W RMS. I am unaware of any other off the shelf driver whose motor structure is only slightly warm after several hours of 1,000 Watts RMS. The long term AES rating of our drivers is 2-3.5kW, depending on the application. The true long term power handing (hours) of a driver is dependent on the driver's ability to dissipate it's thermal energy rapidly and efficiently to the surrounding air. Acoupower's drivers excel at this. This is why our long term power handling is 2-6 times that of current high performance drivers.
We also use a full length copper shorting sleeve. Why use a full length copper shorting sleeve when we are only using a relatively low inductance 2L coil to begin with? Because a full length copper shorting sleeve is the one thing that can be relatively easily implemented that is guaranteed to significantly reduce motor based distortion caused by the coil’s magnetic field. Why not lower the distortion even more if it doesn’t cost much to do? I have been designing speakers and transducers for more than 25 years- this is a “no brainer” if you are making a high performance (low distortion) product. I am sorry to disappoint some of you who thought we had to have the sleeve in there to offset some problem in the design. ONCE AGAIN, PLEASE EVALUATE our products before blasting them. Even without the sleeve, the distortion is low. With it- even lower. BTW, I have an impedance curves of our drivers I would be happy to email anyone. The impedance of our drivers is amazingly flat for a driver of this size.
There has been a lot of comparisons made of our drivers to drivers meant for car use. While we have customers who have put our drivers in cars and are in love, our drivers were not designed for car use (in case the 8 ohm ONLY impedance did not make that point clear on it’s own). For more than six months now, our web site has stated that we do NOT recommend the use of these drivers in ANY confined space, including cars. This is the position we have taken based on the actual capabilities of our drivers and the liability inherent in placing such high output devices in any confined space. Moving on. Car drivers are very different animals. Sub drivers for car use are designed for ENORMOUS power capability for the short term. Nobody cares how much power they take for hours at a time. Car audio sub drivers have extremely heavy voice coils. No doubt about it, these heavy coils can take enormous power levels for short periods of time (many seconds) due simply to their thermal mass. These heavy coils are the primary reason that car subs have low efficiency, NOT to be confused with sensitivity, which can easily be made high by lowering DCR. These heavy coils also have large inductances and generate large amounts of distortion through their interaction with the motor structures. Lastly, the high mass and high inductance of these coils results in a response that drops after 80-100 Hz. In fact, the high inductance in the coil tends to give the typical car sub box a boost in the 60-80Hz range. There is nothing wrong with that for a car, but for high end home or pro-audio use, that is a problem. BTW, Acoupower’s sub drivers also handle unbelievable short term power, due not to their huge weight, but because ALL of the wire is in close proximately to steel and a rapidly moving air flow.
Recapping, Acoupower’s sub drivers feature the following attributes:
1) Very smooth response to several hundred Hz. The -01 15” in particular is flat +-1dB to 500Hz.
2) Reasonably good Sensitivity and very good Efficiency for a very high output and very long throw driver.
3) Very low distortion, even at very high drive levels (this is, by far, the attribute that has been most commented on by our customers).
4) Incredibly high short and long term long term power handling.
5) Inherently shielded motor design.
Acoupower’s 18” vs. 15”. I have received some emails about the parameter differences between the 15” and 18” -01 designs. The 15” units are primarily aimed at high end home audio and high end home theater. The 18” units are primarily aimed at the high end pro-audio market. The -01 15” units work great in sealed and vented boxes and yield awesome response characteristics down to very low frequencies. The 18” are primarily engineered for MAX SPL pro-audio applications which rarely go below 30Hz. They are best implementation in multi-chamber bandpass boxes where the excursions for a given drive voltage are much less throughout a reasonable bandwidth. In such applications, two of our -01 18” drivers can yield SUSTAINED RMS 1m levels of 140dB +-3dB from 30Hz to 100Hz from a single box no more than 20 cu. Ft. in size. Needless to say, along with some pro-audio system manufacturers, we are in the process of re-defining the standard “club” box. Most club boxes had very high output in the 60-100Hz range, but the average response from 30Hz to 60Hz is typically some 6dB less. The +-3dB specs often published here is REALLY pushing the limit on reasonable specifications. Our drivers enable equal size boxes to be built with much higher output in the lower octave while maintaining the output at higher frequencies. In short, a lot more thump, and along with it, lower distortion.
Lastly, our web site is being updated regularly. We will post very nice looking 3-D exploded views of our drivers later this week.
Well, that is enough for now.
Ciao,
Carlos
