noah katz said:
Its simplifing. Things are more complicated.
Why you dont use professional units in home Hi-Fi Loudspeakers?
Does it sound better at 100 dB volume some 3-way loudspeakers with Scan-Speak Relevator units, or some 3-way loudspeakers with JBL (or Electro-Voice or Beyma etc) units?
There is more parameters and kind of distorsion, and different quality of units and many other factors, to amount only to relation excursion-distorsion.
It is true for some of that. For mids its better less excursion and bigger cone, in theory it is like that for bass, BUT why is the trend to make subwoofers with enormius Xmax? Lower freq. needs bigger excursion.
Big bass units (15" or more) with high efficient have a VERY stiff moving system. No meeter high efficient, much power is needed to drive that. Its big cone, rather big Mms. Why valve SE amplifier cant drive this big bass units, if we they have 100 dB/1W/1m or more??
Its not difficult to make high pressure at mid and high freq. but it is difficult make it at low freq. Xmax.
Big units with high efficient have that efficient at average freq. area. What that means? Its from Fc-500 Hz. But every high efficient unit have drop of efficient from about 100 Hz down below. And when you compare bass units of same size with efficienty of 90, 95, 100 dB/1W/1m at loest freq. (like 20-40 Hz) efficient between that at some higger power is not 5 or 10 dB but there are allmost the same. Only metters Sd and Xmax.
Notax said:
Why not?
What I have heard, 6W JC Verdier 300BSE drives 2*TL1601 per side, presents excellent bass response.
My own 4.5W 300BSE drive 2* Eminence SigmaPro18 per side, also presents very good bass. (if not as clean as TAD)
Of course they are not in PA environment but normal living space.
With proper setup, flea wattage DHT amp can also give you very satifying weight/punch/depth/texture on bass. Maybe, flatting out, they can not blow you away or kick the xxxx out of xxx, but absolutely no problem to put a big smile on your face.
So I don't think DHT SE amp "can not" drive big bass unit. Actually they drive them very well.
GM said:
OK, makes sense. When we reduce the angle to half the space, we gain 6dB. Thus 109dB+6dB=115dB. But the 50% efficiency drops us back down to 109dB.
To look at it another way, if a horn and driver combo is really 50% efficient, and driven with 1W of electrical power (1/2 watt of acoustic power produced) then it would radiate:
* 103dB/1W/1m into freespace -- 360x360
* 109dB/1W/1m into half space -- 360x180
* 115dB/1W/1m into quater space -- 180x180
* 121dB/1W/1m into 8th space. -- 180x90
* 127dB/1W/1m into 16th space -- 90x90
Anything less than these SPLs at these angles indicates less than 50% efficiency. Thus we should be able to calculate horn/driver effeciency if we know the SPL at 1 meter and the radiation angle.
Right?
CLS said:
So I don't think DHT SE amp "can not" drive big bass unit. Actually they drive them very well.
Drive them Yes, but very well - not in a million years. I am talking about low freq. Compare with some really good solid state. For units like that at low freq. it is must have amplifier with perfect control, big damping factor and evil power section of amplifier. Try it.
Notax said:
I seems to me that you are talking about the things you don't have much expirience with.
I have 16" Altec-based 2-way and 15" Tannoys at home and few very different amplifiers. SE 300B or PP F2a (no FB, triode mode) drive both speakers very good. In fact, of all the people who listened to those systems neither prefered SS amps.
Already tried it.
I used Kinergetics KBA75 for several years, which got a massive power supply (1KVA power transformer). 75W into 8Ohm, 150W into 4Ohm, seems not very big, but the current supply headroom is much much more than needed for normal home use. I also modded it with more filtering caps & inductors.
Yes, the bass is very good in my memory. Rock solid and all the way down to the bottom of abyss.
At the ultimate comparison of muscles, yes, SS wins. However, it lost in others.
An SS amp with good/powerful bass tends to be high power, which also tends to be with complex circuit & poor low level resolution. It's wasted idle power is high, so overall real-world-SPL/power consumption efficiency is poorer than small power SET amp. (Class D doesn't count here)
Simple & elegant circuit as SET has, so is the sound. Directness, intimacy, tuneful... etc are all their strengths. Massive power & deaf SPL are not needed for home usage. After all, we are using them for playing music, aren't we? So I still think it's well driven.
Yes, I admit sometimes I miss the SS amp of their authority at the 1~2% of the very bottom. However, I'm more than happy to give it up & live with flea power SET, because I got other excellent 98~99%.
That's me, and, well, sorry for off topic.
I used Kinergetics KBA75 for several years, which got a massive power supply (1KVA power transformer). 75W into 8Ohm, 150W into 4Ohm, seems not very big, but the current supply headroom is much much more than needed for normal home use. I also modded it with more filtering caps & inductors.
Yes, the bass is very good in my memory. Rock solid and all the way down to the bottom of abyss.
At the ultimate comparison of muscles, yes, SS wins. However, it lost in others.
An SS amp with good/powerful bass tends to be high power, which also tends to be with complex circuit & poor low level resolution. It's wasted idle power is high, so overall real-world-SPL/power consumption efficiency is poorer than small power SET amp. (Class D doesn't count here)
Simple & elegant circuit as SET has, so is the sound. Directness, intimacy, tuneful... etc are all their strengths. Massive power & deaf SPL are not needed for home usage. After all, we are using them for playing music, aren't we? So I still think it's well driven.
Yes, I admit sometimes I miss the SS amp of their authority at the 1~2% of the very bottom. However, I'm more than happy to give it up & live with flea power SET, because I got other excellent 98~99%.
That's me, and, well, sorry for off topic.
AndrewT said:
I didnt write much Watts. I wrote Control. Hiraga 2x8W (with 500.000 uF each channel) and valve SE 2x8 W is not the same.
Other thing is dynamic range. If you load it with avarage 1-2 W, and in moment have dynamic peak of +20 dB, how to get it from 8 W in class A when 8 W is maximum with constant curent? At low power 0.2-0.3 W avarage, 8 W is enough for biggest slams in some complex music with wide dynamic range.
I am talking about low bass freq. range.
I guess there are 2 approaches regarding horn design: Aiming for maximum efficiency or maximum sensitivity.
I understand maximum efficiency as converting as much as possible electrical input power to acoustical power, and maximum sensitivity as 'maximum acoustical output for a given electrical input voltage'.
Is there a difference between these 2 approaches? Higher efficiency means more acoustical power for a certain amount of electrical power, and thus increasing acoustical output from the horn for a given electrical input power, right?
So for max sensitivity you'd need maximum efficiency.
As I see it, there isn't a difference between max. sensitivity and max efficiency; Max sensitivity requires max efficiency, and max efficiency leads to maximum sensitivity....
I'm sure there's a difference between the two, but I just don't see it...
I understand maximum efficiency as converting as much as possible electrical input power to acoustical power, and maximum sensitivity as 'maximum acoustical output for a given electrical input voltage'.
Is there a difference between these 2 approaches? Higher efficiency means more acoustical power for a certain amount of electrical power, and thus increasing acoustical output from the horn for a given electrical input power, right?
So for max sensitivity you'd need maximum efficiency.
As I see it, there isn't a difference between max. sensitivity and max efficiency; Max sensitivity requires max efficiency, and max efficiency leads to maximum sensitivity....
I'm sure there's a difference between the two, but I just don't see it...
Hi,
I'm still pretty new to this horn stuff, but once you have a horn shape that shape determines the projection of sound towards your audience.
With the horn shape fixed, any gain in efficiency will be exactly proportional to gain in sensitivity.
So you surnise correctly. Efficiency and sensitivity are effectively the same thing.
However there is much more to horn design than just efficiency/sensitivity.
Distortion, power handling, bandwidth, frequency response, etc.
All these will influence your choices for the physical sizes and shapes of the horn including both the front horn/ front chamber and the rear chamber if any.
I'm still pretty new to this horn stuff, but once you have a horn shape that shape determines the projection of sound towards your audience.
With the horn shape fixed, any gain in efficiency will be exactly proportional to gain in sensitivity.
So you surnise correctly. Efficiency and sensitivity are effectively the same thing.
However there is much more to horn design than just efficiency/sensitivity.
Distortion, power handling, bandwidth, frequency response, etc.
All these will influence your choices for the physical sizes and shapes of the horn including both the front horn/ front chamber and the rear chamber if any.
“Why you dont use professional units in home Hi-Fi Loudspeakers?”
I’m building some right now, and many others already use such systems.
In fact many are saying that systems using efficient pro woofers (sub still required, though) and compression drivers on waveguides are every bit as clean as conventional high end designs, but with far superior dynamics.
“True, but it's not relevant to a horn's efficiency rating. What we're talking about here is that a driver/horn combo with enough compression for a theoretical 100% efficiency will burn off half its power just trying to overcome its acoustic resistance.”
Actually we were talking about efficiency and you brought in power compression.
A typical compression driver/horn can put out earsplitting SPL with very little power dissipation and power compression of only a fraction of a dB.
I’m building some right now, and many others already use such systems.
In fact many are saying that systems using efficient pro woofers (sub still required, though) and compression drivers on waveguides are every bit as clean as conventional high end designs, but with far superior dynamics.
“True, but it's not relevant to a horn's efficiency rating. What we're talking about here is that a driver/horn combo with enough compression for a theoretical 100% efficiency will burn off half its power just trying to overcome its acoustic resistance.”
Actually we were talking about efficiency and you brought in power compression.
A typical compression driver/horn can put out earsplitting SPL with very little power dissipation and power compression of only a fraction of a dB.
The latter isn't necessarily true.
Some large horn loaded systems seem to surpass 100% efficiency when the sensitivity is measured and calculated back to efficiency. This due to the increased directivity of the system.
Sensitivity is therefore derived from multiple factors, with efficiency just being one and so it doesn't have to lead to maximum sensitivity.
A 25% efficient bass horn will have lower sensitivity in 1/2 space opposed to 1/4 space (and so on). Thus a 12,5% efficient bass horn can have higher sensitivity than a 25% efficient horn if the difference of loading into space is significant enough.
The efficiency and sensitivity are connected through the following formula:
SPL = 112 + 10.log efficiency (not in % so n0 divided by 100).
Look at it this way: Efficiency is stated in % and so has a upper and lower limit. Sensitivity doesn't have an upper limit (unit based) so it must be different.
With kind regard Johan
noah katz said:
Greets!
Altec-Lansing cinema sound system components have been my HIFI choice for over four decades.
Distortion is vanishingly low, so much so that most folks consider them way too 'dry' sounding for their tastes at HIFI SPLs, and with an in-room efficiency of ~100 dB down to ~60 Hz, I can reproduce an uncompressed recording near/at live levels if I choose without obvious distortion. OK Noah, please explain to me the difference between a compression driver dissipating half of its input power as heat to attain a theoretical 50% acoustic efficiency and a point source driver that's got 3 dB of thermal power compression due to VC heating. I mean the compression driver's VC has got to heat up until its Re is doubled just to overcome the horn's acoustic resistance, so what is it if it's not thermal power compression?
WRT the rest, you're just rephrasing Magnetar's point, so again, not relevant per se since even a 10:1 CR driver is designed to absorb considerable heat before there's any thermal power compression above and beyond what's required to overcome its acoustic resistance. Anyway, a typical horn lens reduces such a driver's efficiency to gain BW, so its initial thermal compression is much lower than the theoretically perfect horn.
GM
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