My previous HE speakers have found a new home. Just in case you don't remember them, here is a pic:
The build thread is here: http://www.avforums.co.za/index.php/topic,6339.0.html
It will be a sad goodbye, but not to worry: I have a new plan up my sleeve ;D
I finally decided to bite the bullet, and went to visit my friend Max at Audio Geometry to get some good drivers. Tomorrow I will be taking delivery of the following:
He doesn't have stock of the compression driver I wanted (ND1030), but will get them for me in the new year. For now tho, I will be using these:
18Sound HD125 on a XT120 horn: http://www.eighteensound.com/index.aspx?mainMenu=view_product&pid=262
For the midrange, I decided on the 6ND410: http://www.eighteensound.com/index.aspx?mainMenu=view_product&pid=244
For the bass, I have 2 per side of the 12W500: http://www.eighteensound.com/index.aspx?mainMenu=view_product&pid=223
I did simulations on pretty much all the 18Sound bass drivers, and the 12W500 sims the best out of the lot even though it is not the largest or can handle the most power. It gives me acceptable bass out of a cabinet size that I can live with. I am trying to hit between 52 and 60Hz F3 with them (the IB will take care of the rest), and I can get that in a 70 lit cabinet tuned anywhere between 48 and 60Hz.
Sensitivity wise (from the published specs), the HD125 comes in at a whopping 109 dB per Watt, the 6ND610 comes in at 102 dB per Watt, and the 12W500 comes in at 99.5 dB per Watt.
If one bass driver has a sensitivity of 99.5 dB, then two would have an efficiency of +3 dB, being 102.5 dB per watt. This is higher than what the midrange would be when the XO has been implemented (because the XO will tap some of the sensitivity from the mid and tweeter), so why would you want your bass more sensitive than your mid?
The answer lies in a little detail called baffle step compensation (BSC). Firstly, I think the bass drivers will be a bit less sensitive than the published figures, and secondly the BSC will be to the tune of about 3 dB, meaning that I will most probably end up with the bass region being around 97 dB per Watt. The 97 dB per Watt ties up nicely with the published figures on the midrange at about 600 Hz.
Now, if I only had one bass driver, I would end up with bass being only 94 dB per Watt, which means more padding (and phase issues) on the mid and tweeter.
As far as dynamic headroom goes, the 2 bass drivers together should be good for between 128 and 130dB worth of acoustic energy (obviously not at the very low frequencies where xmax becomes an issue).
I am not yet sure of how I will end up building the cabinets or in which shape they will be, but I am leaning towards 3 cabinets per side in a WTMW configuration with cabinets as follows: Top bass driver in it's own cabinet, mid and tweeter together in a smaller cabinet, and bottom bass driver in it's own cabinet. That will make them easier to move around as well.
If you have any good ideas on cabinet design, or anything else you would like to share, please do so - your input is always valued.
Have a good evening further.
Ian.
The build thread is here: http://www.avforums.co.za/index.php/topic,6339.0.html
It will be a sad goodbye, but not to worry: I have a new plan up my sleeve ;D
I finally decided to bite the bullet, and went to visit my friend Max at Audio Geometry to get some good drivers. Tomorrow I will be taking delivery of the following:
He doesn't have stock of the compression driver I wanted (ND1030), but will get them for me in the new year. For now tho, I will be using these:
18Sound HD125 on a XT120 horn: http://www.eighteensound.com/index.aspx?mainMenu=view_product&pid=262
For the midrange, I decided on the 6ND410: http://www.eighteensound.com/index.aspx?mainMenu=view_product&pid=244
For the bass, I have 2 per side of the 12W500: http://www.eighteensound.com/index.aspx?mainMenu=view_product&pid=223
I did simulations on pretty much all the 18Sound bass drivers, and the 12W500 sims the best out of the lot even though it is not the largest or can handle the most power. It gives me acceptable bass out of a cabinet size that I can live with. I am trying to hit between 52 and 60Hz F3 with them (the IB will take care of the rest), and I can get that in a 70 lit cabinet tuned anywhere between 48 and 60Hz.
Sensitivity wise (from the published specs), the HD125 comes in at a whopping 109 dB per Watt, the 6ND610 comes in at 102 dB per Watt, and the 12W500 comes in at 99.5 dB per Watt.
If one bass driver has a sensitivity of 99.5 dB, then two would have an efficiency of +3 dB, being 102.5 dB per watt. This is higher than what the midrange would be when the XO has been implemented (because the XO will tap some of the sensitivity from the mid and tweeter), so why would you want your bass more sensitive than your mid?
The answer lies in a little detail called baffle step compensation (BSC). Firstly, I think the bass drivers will be a bit less sensitive than the published figures, and secondly the BSC will be to the tune of about 3 dB, meaning that I will most probably end up with the bass region being around 97 dB per Watt. The 97 dB per Watt ties up nicely with the published figures on the midrange at about 600 Hz.
Now, if I only had one bass driver, I would end up with bass being only 94 dB per Watt, which means more padding (and phase issues) on the mid and tweeter.
As far as dynamic headroom goes, the 2 bass drivers together should be good for between 128 and 130dB worth of acoustic energy (obviously not at the very low frequencies where xmax becomes an issue).
I am not yet sure of how I will end up building the cabinets or in which shape they will be, but I am leaning towards 3 cabinets per side in a WTMW configuration with cabinets as follows: Top bass driver in it's own cabinet, mid and tweeter together in a smaller cabinet, and bottom bass driver in it's own cabinet. That will make them easier to move around as well.
If you have any good ideas on cabinet design, or anything else you would like to share, please do so - your input is always valued.
Have a good evening further.
Ian.
