the suggestions for SPL enhancement for "placement" are substantially a bass only idea.
They do not apply when the mid range and treble range start "beaming".
I ignore the bass enhancement for this "loudness" calculation.
If the bass is lacking then placement can and is used to bring the apparent level of the bass up to better match the mid & treble.
They do not apply when the mid range and treble range start "beaming".
I ignore the bass enhancement for this "loudness" calculation.
If the bass is lacking then placement can and is used to bring the apparent level of the bass up to better match the mid & treble.
Shouldn't that be 91dB at 1W
94dB at 10W
97dB at 100W
Ten x the power is required to double the volume.
No.
Double the power gives 3dB ratio of SPL.
Ten times the power gives 10dB ratio of SPL.
Double the voltage gives 6dB ratio of SPL.
Ten times the voltage gives 20dB ratio of SPL.
Double the power gives 3dB ratio of SPL.
Ten times the power gives 10dB ratio of SPL.
Double the voltage gives 6dB ratio of SPL.
Ten times the voltage gives 20dB ratio of SPL.
Andrew if you have a room without nothing on the walls then you have reflexions in the midrange+treble area .For example when I clap my hands I still hear more hands clapping 😀
That why I named that parameter placement & reflexions .
But if you have a room with diffuzers & absorbers on the walls then you can avoid those 3 db and speakers plced away from the walls.
That why I named that parameter placement & reflexions .
But if you have a room with diffuzers & absorbers on the walls then you can avoid those 3 db and speakers plced away from the walls.
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Please go read Toole. It is absolutely amazing what putting the speakers AGAINST an absorber front wall does for imaging and smoothness. He told us how to do it 30 years ago! It works.
" We all know the sound of two hands clapping. Who knows the sound of one hand clapping?"
Shelly Berman.
As a side issue perhaps is the power needed from an amp/skr depends on the volume of the room and distance to the listener. So, that has been determined by sound contractors for various size venues. One such source of this type of info can be found on Harmon/JBL/Crown site. It is quite a bit more power for 95dB spl than for speaker tests at 1 meter to prevent clipping and distortion.
View attachment PWR-Venue size.pdf
THx-RNMarsh
View attachment PWR-Venue size.pdf
THx-RNMarsh
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No. Twice the power is +3dB, 10x the power is +10dB. dB is a measure of power, whether it be electrical or acoustic. Since the efficiency of the speaker is constant (unless you're cooking it), then +X dB of electrical power is +X dB of acoustic power.
However, +10dB seems about twice as loud, psychoacoustically. Ears are strange and inaccurate.
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I have very sensitive vintage field coil speakers and I had a similar epiphany about power usage about a year ago. i have Valve amps which can produce between 7W for one and 20W for the most powerful. All run in class A. I realized after a chance measurement that I almost never use more than 1W so i decided to build a SPUD amp with an output power of 3W. It can drive the speakers into distortion before I seriously run out of power.
I would like to experiment with a high quality transistor amp in the same power range as my SPUD - but cannot for the life of me find any designs at that low power which claim to be anything other than transistor radio quality. Any ideas ?
Shoog
I would like to experiment with a high quality transistor amp in the same power range as my SPUD - but cannot for the life of me find any designs at that low power which claim to be anything other than transistor radio quality. Any ideas ?
Shoog
For 3W into 8ohms you need 4.9Vac.
That is equivalent to 6.9Vpk and 13.8Vpp
For a single ended amplifier you would need ~13.8 plus losses through the amp for a target PSU voltage.
Try 18Vdc or 20Vdc.
Go to Pass and copy one of his SE designs.
That is equivalent to 6.9Vpk and 13.8Vpp
For a single ended amplifier you would need ~13.8 plus losses through the amp for a target PSU voltage.
Try 18Vdc or 20Vdc.
Go to Pass and copy one of his SE designs.
There is no mention of speaker sensitivity in your attachment.
"Folk music in a coffee shop with 50 seats: 25 to 250W" , oh well, I might
add "young people need 100 if not 200W".
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I used my UNI-T 71E. But I'd assume that any other meter would work as well.
The D Amp is a AMP-6B from 41Hz built in a little box from Modushop with a little SMPS. Couple of photos can be found here: http://www.diyaudio.com/forums/class-d/87913-class-d-amp-photo-gallery-16.html#post3592112
Hi Guys
A low-wattage amp does not have to sound small. The problem is that most commercial offerings assume that a low-watt system is for "non-serious" listeners, so circuit refinements are skimped on and performance is not at all like higher-wattage items from the same manufacturer. This is a widespread problem throughout the industry.
Power has also become a lot less expensive over the years, so for the cost of a 10W amp of olde it is easy to have 100W+. Most of the cost is in the power transformer, chassis and heat sink. The latter can be pretty small with modern linear techniques.
If you are in a position to build your own amp, and you only want low power, then you have options. You can build a class-A amp without the heat penalty that a "large" amp incurs. I built myself a "super power" class-A system with 8Wpk/ch into 4R.The output stage operates from +/-8V or so, and idles at 700mA split between two pairs of output devices.
My usual listening level is in the 10s of milliwatts as I have speakers that are 90dB/1W@1m.
All of the techniques for distortion reduction can be applied to a low-watt amp: multiple parallel output pairs, output-inclusive compensation, non-output non-miller comp, high-Ft devices throughout, etc,
All the claims of how much power is needed for live performances, whether in small venues or large, is based on a histoty of lethargic disregard for the hearing safety of the audience. 100s of watts for a coffee house? That's ridiculous. The musicians have obviously overlooked the fact that they are not the attraction: coffee and chatting is. Same goes for most bars: the band is there as background music and should not be drowning out the audience.
I listen to all kinds of music. There are very few properly recorded live performances where dynamic range tests the system: those from the Dorian recording group (all classical, direct to disc, unfortunately put out of business by greedy investors), the Rainbow 'On Stage' album, to name some, but these are few and far between. I have tonnes of headroom in my system. I can't stand 90dB SPL - I've measured it in my room - more usual levels are mid-70s or so.
Most people are unaware of how low the SPL number is when they perceive it to be loud, and are also unaware of how little power they normally use.
Have fun
Kevin O'Connor
A low-wattage amp does not have to sound small. The problem is that most commercial offerings assume that a low-watt system is for "non-serious" listeners, so circuit refinements are skimped on and performance is not at all like higher-wattage items from the same manufacturer. This is a widespread problem throughout the industry.
Power has also become a lot less expensive over the years, so for the cost of a 10W amp of olde it is easy to have 100W+. Most of the cost is in the power transformer, chassis and heat sink. The latter can be pretty small with modern linear techniques.
If you are in a position to build your own amp, and you only want low power, then you have options. You can build a class-A amp without the heat penalty that a "large" amp incurs. I built myself a "super power" class-A system with 8Wpk/ch into 4R.The output stage operates from +/-8V or so, and idles at 700mA split between two pairs of output devices.
My usual listening level is in the 10s of milliwatts as I have speakers that are 90dB/1W@1m.
All of the techniques for distortion reduction can be applied to a low-watt amp: multiple parallel output pairs, output-inclusive compensation, non-output non-miller comp, high-Ft devices throughout, etc,
All the claims of how much power is needed for live performances, whether in small venues or large, is based on a histoty of lethargic disregard for the hearing safety of the audience. 100s of watts for a coffee house? That's ridiculous. The musicians have obviously overlooked the fact that they are not the attraction: coffee and chatting is. Same goes for most bars: the band is there as background music and should not be drowning out the audience.
I listen to all kinds of music. There are very few properly recorded live performances where dynamic range tests the system: those from the Dorian recording group (all classical, direct to disc, unfortunately put out of business by greedy investors), the Rainbow 'On Stage' album, to name some, but these are few and far between. I have tonnes of headroom in my system. I can't stand 90dB SPL - I've measured it in my room - more usual levels are mid-70s or so.
Most people are unaware of how low the SPL number is when they perceive it to be loud, and are also unaware of how little power they normally use.
Have fun
Kevin O'Connor
Care to share your schematic.
The problem with the other suggestions is I prefer PP to SE as it avoids the need for an output cap.
Shoog
The problem with the other suggestions is I prefer PP to SE as it avoids the need for an output cap.
Shoog
Hi Guys
Nothing unusual about the design: fully complementary, with EF-VAS, and class-A direct current control biasing, output stage is a Quad Complementary type wired as a follower.
Note that the front end including the EF-VAS is very much like the Ampzilla of 1974, although that was not the basis of the amp I built.
Like I said, there is nothing different about building low-power vs high-power except for the supply voltages and heat dissipation. Obviously a much smaller PT can be used and you can take that a step further and have separate supplies for each PA.
When "low power" is mentioned in most circles, you will get the usual response of "SE tube amp", "SE solid-state", or a suggestion to look at the primitive amps by Pass and JLH. Those are not hifi - although some can be if driven only to very small levels.
At low power levels, noise is the main thing to control.
Have fun
Kevin O'Connor
Nothing unusual about the design: fully complementary, with EF-VAS, and class-A direct current control biasing, output stage is a Quad Complementary type wired as a follower.
Note that the front end including the EF-VAS is very much like the Ampzilla of 1974, although that was not the basis of the amp I built.
Like I said, there is nothing different about building low-power vs high-power except for the supply voltages and heat dissipation. Obviously a much smaller PT can be used and you can take that a step further and have separate supplies for each PA.
When "low power" is mentioned in most circles, you will get the usual response of "SE tube amp", "SE solid-state", or a suggestion to look at the primitive amps by Pass and JLH. Those are not hifi - although some can be if driven only to very small levels.
At low power levels, noise is the main thing to control.
Have fun
Kevin O'Connor
Choice of suitable transistors would seem to be an issue.
I have some nice salvaged big Sankens which I have been dying to use for ages. I found a good Diamond Buffer design which could use them but I then still have to add a front end to it.
Coming from the world of hollow state - this is all new terminology for me. The nice thing with valves is you can achieve amazing levels of performance with remarkably simple circuits.
The overall objective is to see if i can build a design to match my hollow state's level of performance whilst increasing the overall efficiency. Class A is desirable - but only if I am not wasting significant heat to give me unnecessary reserves of power.
3watts output is all I want it to do, and PP has proven itself a superior choice in the past.
Shoog
I have some nice salvaged big Sankens which I have been dying to use for ages. I found a good Diamond Buffer design which could use them but I then still have to add a front end to it.
Coming from the world of hollow state - this is all new terminology for me. The nice thing with valves is you can achieve amazing levels of performance with remarkably simple circuits.
The overall objective is to see if i can build a design to match my hollow state's level of performance whilst increasing the overall efficiency. Class A is desirable - but only if I am not wasting significant heat to give me unnecessary reserves of power.
3watts output is all I want it to do, and PP has proven itself a superior choice in the past.
Shoog
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Hi Guys
Shoog, what I described is a push-pull solid-state amp that is thoroughly modern and yet traditional. At low power levels, you can use nearly any BJTs you wish - you are not restricted by supply voltage since that is low.
The mistake most builders make when they look at a low power amp is to use tiny parts and try to simplify the circuit more than they should. That is actually two mistakes...
Using a diamond for the output stage is a mistake. You need control over the idle condition and the diamond offers no simple way to do that nor does it offer a simpler circuit than any of the standard EF, EF2, EF3 or CFP outputs. All of the latter provide much more drive current, where the diamond has an inherent cap on drive current due to its arrangement. Diamonds are neat but not simpler and not always the best choice.
Many use a diamond buffer inside an opamp loop, then the opamp determines overall performance slightly aided by the buffer for part of the frequency range and increasingly impeded by the buffer if the buffer's idle point is not set to reduce crossover distortion. Class-A does not mean "short proof".
In my amp with its low output rails, idling at 700mA leads to about 11W of heat per channel. Even with a 1C/W heat sink this causes only an 11C rise above room temperature. pretty good for a class-A amp. I chose class-A to eliminate crossover distortion. All the devices could just as easily be used in a 300W amp given their ratings. Making the output stage robust allows leaving out protection circuits other than fuses for the supplies. It helps that the load for each amp is known.
If you build the amp and it sounds lifeless and uninteresting then it is very likely truly neutral. The "euphonic" amps all have THD galore with increasing amounts with signal. Those are not hifif but you may prefer something like that if you are coming from the tube world. I've built tube amps as well but prefer the easier path to true low distortion that solid-state provides. Most people have never heard a truly low-THD system with knowledge that that ws the case. When confronted with such a system, it is initially uninteresting. Until you learn the difference between "accurate" sound and what you feel to be "good" sound, the low-THD stuff will not please you.
Have fun
Kevin O'Connor
Shoog, what I described is a push-pull solid-state amp that is thoroughly modern and yet traditional. At low power levels, you can use nearly any BJTs you wish - you are not restricted by supply voltage since that is low.
The mistake most builders make when they look at a low power amp is to use tiny parts and try to simplify the circuit more than they should. That is actually two mistakes...
Using a diamond for the output stage is a mistake. You need control over the idle condition and the diamond offers no simple way to do that nor does it offer a simpler circuit than any of the standard EF, EF2, EF3 or CFP outputs. All of the latter provide much more drive current, where the diamond has an inherent cap on drive current due to its arrangement. Diamonds are neat but not simpler and not always the best choice.
Many use a diamond buffer inside an opamp loop, then the opamp determines overall performance slightly aided by the buffer for part of the frequency range and increasingly impeded by the buffer if the buffer's idle point is not set to reduce crossover distortion. Class-A does not mean "short proof".
In my amp with its low output rails, idling at 700mA leads to about 11W of heat per channel. Even with a 1C/W heat sink this causes only an 11C rise above room temperature. pretty good for a class-A amp. I chose class-A to eliminate crossover distortion. All the devices could just as easily be used in a 300W amp given their ratings. Making the output stage robust allows leaving out protection circuits other than fuses for the supplies. It helps that the load for each amp is known.
If you build the amp and it sounds lifeless and uninteresting then it is very likely truly neutral. The "euphonic" amps all have THD galore with increasing amounts with signal. Those are not hifif but you may prefer something like that if you are coming from the tube world. I've built tube amps as well but prefer the easier path to true low distortion that solid-state provides. Most people have never heard a truly low-THD system with knowledge that that ws the case. When confronted with such a system, it is initially uninteresting. Until you learn the difference between "accurate" sound and what you feel to be "good" sound, the low-THD stuff will not please you.
Have fun
Kevin O'Connor
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Dude, there is never enough bass. I built sub that demolishes my room at 15-30Hz and it just doesn't seem enough. But it could be just me.
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