Efficiency

[delahais]

Hi,
A set of 802-8G and 511b must at -8dB on filter 501-8A and 30904, which is about-16dB, so the sound is good. Does that mean that the bass (tad 1601) have a poor performance?, Too small a volume (160 liters)?...
Thank you for your answer.
Regards

[Mr. Widget]

Hi,
A set of 802-8G and 511b must at -8dB on filter 501-8A and 30904, which is about-16dB, so the sound is good. Does that mean that the bass (tad 1601) have a poor performance?, Too small a volume (160 liters)?...
Thank you for your answer.
RegardsI am sorry, but could you word your question differently? I don't understand your question. Perhaps others are also having trouble and that is why no one has answered.


Widget

[toddalin]

I think he means that there is a big discrepancy between the efficiency of the horn/driver combination and the woofer, and "would increasing the volume of the woofer cabinet let the woofer be more efficient to better match the horn/driver combination?"

[delahais]

I think he means that there is a big discrepancy between the efficiency of the horn/driver combination and the woofer, and "would increasing the volume of the woofer cabinet let the woofer be more efficient to better match the horn/driver combination?"


Yes it's what i mean, i'll post some pictures and more informations perhaps this evening.
thanks.

[Mr. Widget]

Yes it's what i mean....You do realize that cone woofers are inherently less sensitive than horn loaded compression drivers. This difference can be as much as 20dB and as little as 7-8dB depending on the design of the woofer. In general the woofer's sensitivity is increased at the cost of low end output... i.e., a "high efficiency" woofer will not reproduce lower frequencies as loudly as it does midband frequencies. The only way you can increase the sensitivity "efficiency" of a cone woofer is by placing a very large horn in front of it.

Changing the box size one way or the other will not change the sensitivity of a woofer. You will change the low frequency loading, but above say 100-200Hz, the box will not have any effect on the woofer's output except perhaps in bad ways with the possibility of standing waves etc.


Widget

[Lee in Montreal]

Just to put in perspective what 20db difference is and if modifying the enclosure will get you that difference back, here's a very simple explanation.

3db = double the sound level

To double the spl, you need twice as many drivers. Therefore, if instead of one woofer, two were used, then you'd gain 3db. To gain 6db, you need double the woofers, that's four woofers now. To gain 9db, you need 8 woofers... and so one and so on.

That's a lot of woofers to be level with the horn... ;)

So, to summarize my reply. No, changing the enclosure itself is not enough to put the woofer and midhorn level.

[delahais]

Hi,
yes you're right, because the sound is good, the matter was when i looked the x-over on microcap I did not understand. now it's ok. the problem is that these drivers can make things better and better and seem limitless...
hereafter you can see the x-over...
i'll post pictures of the enclosure, soon...
regards.

there is a zobel on the tad = 20uF and 7.5 ohms.

[ivica]

Hi,
yes you're right, because the sound is good, the matter was when i looked the x-over on microcap I did not understand. now it's ok. the problem is that these drivers can make things better and better and seem limitless...
hereafter you can see the x-over...
i'll post pictures of the enclosure, soon...
regards.

there is a zobel on the tad = 20uF and 7.5 ohms.

Concerning the drivers sensitivity (802-8g with mentioned horn), first rise (amplify) data from MicroCap (for 802 bout 17dB, and for 2405 about 12dB), and take in mind the drivers responses
My be http://www.hostboard.com/forums/f700/54116-altec-802-8g-model-19-a/index4.html#post359061
can help.
In any case "fine tuning" of network elements would be 'well come' in order to get 'flat' response.

[delahais]

Hi,
Here are some pictures of my system (study) I wonder if two events are not too much for a low power listening <<3watts in a living room. is there a relationship between the pressure in the enclosure and power, bad for a low-power listening?
or physical laws still valid in low power...
regards

[delahais]

Concerning the drivers sensitivity (802-8g with mentioned horn), first rise (amplify) data from MicroCap (for 802 bout 17dB, and for 2405 about 12dB), and take in mind the drivers responses
My be http://www.hostboard.com/forums/f700/54116-altec-802-8g-model-19-a/index4.html#post359061
can help.

Hi Ivida,
thanks for your post, I wonder if I will not try to change the capacitors 28uF for 20-24uF
because the inductors are only 2,8mH in reality...it's strange...
regards.

[ivica]

Hi Ivida,
thanks for your post, I wonder if I will not try to change the capacitors 28uF for 20-24uF
because the inductors are only 2,8mH in reality...it's strange...
regards.

First measure the response, and then decide if some tuning is necessary. Do not be amazed about (comb-filter http://en.wikipedia.org/wiki/Comb_filter ) bouncing in UHF region (because of great time difference -long horn length- between 802-8g and 2405)