You don't get out much I gather, seriously artisanal farming has been doing quite well, try your local ethnic communities.
Maybe the design was tested outside or speaker backed into hole.Ah the days of MIT in 1970, the rich kids would point their Bose 901's out the window and crank up their 250W Sansilly receivers to Iron Butterfly. Frank would love it.
My neighbor had 901's with the big Bose Amplifiers. 1976, I do remember enjoying that system in his dedicated room, room location is very important , as distance from the rear wall..
Ohh, i get out much and afar and eat Ethnic, Daily, I was talking American cuisine, specifically KFC ..
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Ohh, i get out much and afar and eat Ethnic, Daily, I was talking American cuisine, specifically KFC ..
There are plenty of good young American chefs too. I'm not sure I would call KFC cuisine, not sure there is such a thing unless one considers the colonial days derived from Brit cooking (I shudder to think).
What most people don't appreciate is that if an audio setup can do a symphony crescendo at realistic volumes with complete control, then it can also do Iron Butterfly, Jimi Hendrix, etc, etc, impeccably. Intense sound, with no raucousness or slide into sludginess is a remarkable thing to experience, the ear/brain adjusts and can handle almost crazy levels of SPLs without subjective discomfort.
Of course, virtually all PAs will do the volume but fare miserably on clarity - fail! And quality audio will do clarity, but then starts to fall apart with increasing volume - fail! The trick is to have both factors happening together - and then this is when one gets truly "special" sound ...
Of course, virtually all PAs will do the volume but fare miserably on clarity - fail! And quality audio will do clarity, but then starts to fall apart with increasing volume - fail! The trick is to have both factors happening together - and then this is when one gets truly "special" sound ...
I feel you often talk about SPL's that do permanent ear damage, the fidelity is irrelevant. I need to take you to an extreme Japanoise "concert".
Masonna - god of noise - YouTube
The musicians constantly experience intense sound, have been doing so for literally 100's of years - that's what gives them the 'buzz'. If they're silly about it then they get ear damage, but if they rest inbetween sessions then the ear recovers; when was the last time an orchestra conductor wore ear plugs doing his job? And I get the impression that fidelity at high volumes, for him, is important ...
I think you threw out 130dB the other day, not safe under any circumstances.
I was working with some premium hearing aid guys recently. They had many stories about tuning hearing aids for classical musicians who have serious hearing damage. The tuning with those guys was painful since they want something they can't get back. its much different that for normal people with hearing loss.
Damaged hearing does not recover. Those OSHA rules are not a joke, if anything they are way too loose.
Its another reason why a musician may not be the best judge of sound. . .
Because that is the actual, transient, peak intensity that some instruments can produce - tympani, rim shots on drums, for example. But just because that momentary impulse of sound is produced, doesn't mean that the listener should constantly expose himself to such elevated levels, the average intensity exposure over a period of time will be far more important, from a health POV.
The point is not to incur hearing damage, it is to hear subjectively intense, enthralling sound - there is a very usable midpoint between the overly "nice" sound much audio comes across with, and the severely overcooked, PA intensified, blast of sound at many concerts. Maximum volume on my currently underpowered, low level systems gives me a decent taste of that 'better' sound, especially on classical material - where most systems go wrong is that when used at that level setting they tend to sound unpleasant, to put it mildly ...
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Did I say I wanted "loud", a.wayne? That 112dB sounds about right, if I get that as a peak level, totally clean, then I would be happy with that; and it's very easy to put together a system using standard gear that will do that, theoretically ... but usually when working at that level everything is starting to fall apart, it's sounding very strained indeed - it has to do that volume with total ease, as if it's a mere piffle to achieve such - it's the sense of nothing being untoward at those SPLs that is part of creating convincing sound ...
Unless one has very efficient loudspeakers, 112 dB peaks, and clean, will require some whopping amplification.
Theoretically, my Karan amp delivers 22 dBW as standard specs, while my speaker do 92 dB/2.83V/1m. So, I should be able to expect peaks of (92+22) 114 dB at 1m. But that amp delivers 180W/8 Ohms. So if one's speakers are of the 89 dB/2.83V/1m persuasion, that power would need to double. But if I owned say JBL 4312, rated at 95 dB/2.83V/1m, that power could halve.
Not the simplest of things to achieve, and I fear the reasoning is beyond most people. I am constantly amazed at how randomly people purchase gear.
Theoretically, my Karan amp delivers 22 dBW as standard specs, while my speaker do 92 dB/2.83V/1m. So, I should be able to expect peaks of (92+22) 114 dB at 1m. But that amp delivers 180W/8 Ohms. So if one's speakers are of the 89 dB/2.83V/1m persuasion, that power would need to double. But if I owned say JBL 4312, rated at 95 dB/2.83V/1m, that power could halve.
Not the simplest of things to achieve, and I fear the reasoning is beyond most people. I am constantly amazed at how randomly people purchase gear.
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Maybe the design was tested outside or speaker backed into hole.
Scott . In think this is your field . How do engineers progress to a finished op amp design ? Is it made in discreet components to test even if not exactly the same ? To commit money to a production run I was told costs $120 000 to get 10 sample devices when communications chips . I remember an engineer saying the LM 324 was a disappointment yet was OK for the market intended . That suggests especially then some of it was fingers crossed .
Joe was loosely speaking an oilman ( clean up ) . The way he approached the 901's was in oilman mode . Regardless of my expertise albeit modest he was the boss as he choose the 901's . " you see Nigel the 901 blah blah blah " . To be honest I love being told stuff and how it's told is the best .
I dare say . I don't like the asymmetry of designs like that . I like double VAS . The Hitachi amp only has 5 transistors , 2 MOS FET and one diode . Yet it has virtues that most do not attempt . Symmetrical 35 V/uS from a design not looking to be special. Duties shared between PNP and NPN LTP . Reasonable balance throughout supported by very low 50 kHz distortion . The input pair tail served by a resistor . All my test make it very hard to prove the resistor is the worst choice . If below -80dB my ears won't hear it .
About slewing . As far as I can tell slewing in nonsense . However it is the easier route to solving other problems . Realistically a 100 watt amp needs 2 V/uS to reproduce real music . This is usually uprated to 6 V/uS for caution . It is like the Sun goes around the Earth . Without the concept of an ellipse it is hard to say not true . 7 years of calculation checked 80 times to say what we now know .
So how is it that we find fast slew rate amps better ? My guess is the input wave we see to the VAS is not a ghost . As most will know the greatest transfer is when the source resistance /impedance matches the base of the VAS . As this input impedance is not anything like resistance the waveform is highly distorted . Out of the collector comes a very nice wave not unlike the input wave . Up to this point everything was a current amplifier . Hence the tail to the input pair being OK as a resistor . Thus all is well in the world ? Not really . Loose a bit of the current pumping to see a less distorted wave . This can be by a series resistance or VAS emitter resistor . My feeling is high slew rates are to allow better operation attempting trans-conductance into the VAS . This can be proved where ancient amps are upgraded by fine tuning VAS Re . Suddenly all the gritty sound is gone . As Bob Stewart said TID can be mistaken for crossover distortion .
To illustrate the point . Goodmans Module 80 amp ( about 1974 ) seems to be a hastily upgraded germanium design . All PNP silicon ( 2N2955 ) . Now that has to be the most bonkers idea ever . The VAS is fed by a pot that also adjusts mid volts . Pot set typically to 2K4 . VAS is u= 100 at 11 mA . The emitter has a diode to 0V . Replacing the diode with 56R gives identical static conditions . The sound is transformed . This was some work I gave to my brother . He did a Dvv job on the capacitors , polystyrene where possible . Apparently this amp was taken to many hi fi shops to use when choosing . Apparently the shops were taken aback as it had become a giant killer . This was a guy who was having a Garrard 401 serviced . Otherwise I would have said no .
Analyze the Bob Stewart amp if you have time .
This is a simplified Blomley amp circa 1971 . Used by Philips Mullard amplifier modules I think ? It is claimed to reduce crossover distortion at HF . I would love to use this to drive headphones . My only doubt being a reasonable input impedance if not using a buffer . Some guy in Holland did a modern version with NE5534 as the driving device .
I wouldn't call 180W "whopping amplification" - but making that happen cleanly might be "whopping" hard! In my personal experience, 60W of well sorted out amp power into typical sensitivity speakers, say 90dB, is good enough for a normal room - this gets you into the mid 100dB+ levels, and delivers highly satisfying sound; certainly will allow completely realistic reproduction of an in-room piano, say.
Since 6dB change is subjectively almost nothing, if I was doing a range of system capabilities I would do steps of 12dB - start with 108, then 120, and lastly 132dB. The first one would be adequate for nearly everything, the other two for those who insist on having the biggest toys ...
Frank, 180W78 Ohms IS a pretty powerful amplifier, all the more so since it is an integrated amp (line only, 4 RCA and 1 XLR).
Not to split hairs, but what would say, 150W/8 Ohms amps make up for what percentage of the total out there? I would veture a guess and say less than 0.1% of the total, and I think that's being generous.
If you narrow it down to good 150W/8 Ohms amps, reduce the number an order of magnitude. I am a bit weary of popular brand amps which use two pairs of 150W devices per side and claim almost outrageous power figures for 4 and 2 Ohms. In my book, those transistors will be fried to a crisp long before they reach those power level and remain useful, i.e. if you disregard claims good for only 1 mS.
BTW, the said Karan amp uses 2 pairs of Sanken 200W devices in what the maker claims to be a fully balanced topology. I cannot comment, because I have not seen the schematics. He's hiding it like a snake hides its legs, and I have no reason to push it.
When I said "whopping", I referred to a more typical loudspeaker system, which will deliver 2-3 dB of SPL less than mine, with God alone knows (if even He) what kind of phase shi(f)ts. 3 dB will double the power amp requirements and the price, which is why they are relatively rare.
Not to split hairs, but what would say, 150W/8 Ohms amps make up for what percentage of the total out there? I would veture a guess and say less than 0.1% of the total, and I think that's being generous.
If you narrow it down to good 150W/8 Ohms amps, reduce the number an order of magnitude. I am a bit weary of popular brand amps which use two pairs of 150W devices per side and claim almost outrageous power figures for 4 and 2 Ohms. In my book, those transistors will be fried to a crisp long before they reach those power level and remain useful, i.e. if you disregard claims good for only 1 mS.
BTW, the said Karan amp uses 2 pairs of Sanken 200W devices in what the maker claims to be a fully balanced topology. I cannot comment, because I have not seen the schematics. He's hiding it like a snake hides its legs, and I have no reason to push it.
When I said "whopping", I referred to a more typical loudspeaker system, which will deliver 2-3 dB of SPL less than mine, with God alone knows (if even He) what kind of phase shi(f)ts. 3 dB will double the power amp requirements and the price, which is why they are relatively rare.
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