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Amps and receivers are rated RMS power output. But, what can you use without clipping issues at higher volumes? I figured this out with listening to a few receivers. My 40 watt Onkyo TX-2500 starts to clip around 25 watts output and the 50 watt Pioneer SX-1000TW at about 35 watts. It is clearly heard on power demanding bass and I do not have the bass turned up. I do not have a power meter, so it is an estimate. I suspect is close. I am using the standard 87dB sensitive speakers.This brings up a point you may want more power output than estimated. A Marantz 2216 or other receivers up to 30 watts RMS output per channel would be useless to me on my speakers unless used as a background music system. However, if you have sensitive speakers in the 92dB range you would be ok with a 30 watt per channel RMS receiver.
Using 87dB sensitive speakers, you may want to only consider 50 watts RMS per channel or higher power receivers. I find a direct correlation with used 'Golden Age' (1970 to 1980 year) receiver prices and power output on eBay. Starting about $400 and higher is required for a 50 watts RMS per channel receiver on eBay.
80dB SLP listening volume with Speaker sensitivity and power requirement chart including power reduction provision for clipping. The watts column is the receiver or amplifier RMS power requirement:
104db 8 feet 80db 15db 1.5 watt
101db 8 feet 80db 15db 3 watts
98db 8 feet 80db 15db 4.5 watts
95db 8 feet 80db 15db 9 watts
92db 8 feet 80db 15db 18 watts
89db 8 feet 80db 15db 36 watts
88dB 8 feet 80db 15db 48 watts
87dB 8 feet 88db 15db 60 warrs
86db 8 feet 80db 15db 72 watts
83db 8 feet 80db 15db 144 watts
80db 8 feet 80db 15db 288 watts
77db 8 feet 80db 15db 573 watts
SPL Loudness Reference
Jet aircraft, 50 meters away 140 SPL
Threshold of pain 130 SPL
Threshold of discomfort 120 SPL
Chainsaw, 1 meter distance 110 SPL
Disco, 1 meter from speaker 100 SPL
Diesel truck, 10 meters away 90 SPL
Cerbside of busy road, 5 meter 80 SPL
Vacuum cleaner, 1 meter away 70 SPL
Conversational speech, 1 meter 60 SPL
Average home 50 SPL
Quiet library 40 SPL
Quiet bedroom at night 30 SPLNote: the estimated power without clipping is based up average bass level or with loudness switch on still should be ok. If you turn up the bass 3/4 to maximum, the driver will use more power. In this case, I would estimate 1/2 the watts RMS output of an amplifier or receiver to have enough reserve power with the maximum bass setting.
Edits: 05/15/21 05/15/21 05/15/21 05/15/21 05/15/21 05/15/21 05/15/21 05/16/21 05/16/21 05/16/21 05/16/21 05/18/21Follow Ups:
"My 40 watt Onkyo TX-2500 starts to clip around 25 watts output and the 50 watt Pioneer SX-1000TW at about 35 watts"
How did you determine that ? Scope ?
Jurb, reread my original post.
So you "heard" it. And to measure the power ?
If you are going to mess with this stuff maybe you should look in to a cheap used analog scope. A 20MHz is cheap these days. Just put into eBay oscilloscope and then sort by price, lowest first, you will have to get through the parts and the units for parts, but maybe $150 you get a good enough one - as long as it works.
The reason for my skepticism is that I have never seen an amp of any kind of quality clip before it met the rated power output. Usually they clip higher, because for the lower distortion rating they took a lower power rating.
Sometimes you could get the specs. It is called clipping headroom and expressed in dB. Another one is dynamic headroom which is the difference between what it can put out short term with the filters ice and charged, versus what they will do steady state, also expressed in dB.
It is just the unusual nature of your problem there that makes me question.
Jurb, I have a lot of experience and also know parts. In the Onkyo, the transformer size can support a 60 watt RMS per channel amp. The output transistors are rated 80 watts. The capacitors were increased from 8000uF to 18000uF. The power supply has a lot of capacity and can support short term current peaks.The Onkyo did clip on bass notes about 3/4 power. Turn the bass down and it does not clip. Same for my Pioneer SX-1000TW. Power transformer in the 50 watts RMS per channel Pioneer is a little smaller vs the Onkyo.
The bass was set at midrange, but had some boost with the loudness switch engaged on both receivers.
So, I stand by my post.
Edits: 05/18/21
One should consider the power supply rails. I've seen vintage gear rated at 50, 60 and 70 watts all have +- 50v rails. A sine wave without rail sag will produce 155W RMS. That will also be the peak music power. If music has 10db peaks most of the music signal will drive the amp to 15-20watts.
I have a 1980 amp with meters. On dynamic material the meters read 20 watts or so but the clip lights are flashing and a scope on the outputs shows the +- 60 volt peaks. The system is playing very loud then.
Geez, US vintage power numbers post November 4, 1974 are required to be in RMS power, post conditioning, running full bandwidth into a specified load and with a stated maximum distortion.
This has NOTHING to do with how music is using that power. The older music power numbers might have been better but there were too many of them and the feds evened the playing field. We all know the feds don't know anything about stereo and just used what they thought would be a good way to make manufacturers compare apples to apples.
I'm seeing a lot of ak stupid in this thread. I'm going just leave it at that with the agreement that yes, you want more power. Unfortunately, that extra power might not sound as good as a lower powered unit, just allows higher listening volume.
Neither are they vintage or recent Klumsy low Eff drivers were of the High power is easy cheap to make era.
Crap basically.
I was not speaking of vintage speakers. Most new speakers are an average of 87dB.
"Most new speakers are an average of 87dB. "
87 dB speakers need 100W and up per channel. This is why amplifiers like the Phase Linear 300, Dynaco 416 and Bose 1801 were made. Sensitivity numbers in this range are usually the result of combining a sealed, infinite baffle enclosure with low-efficiency woofers featuring high-overhang voice coils and very low Fs.
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Buy Chinese. Bury freedom.
100 Watts? What listening distance sre you referring to? 80dB SPL is loud on 87dB speakers at 8 feet listening distance. Cannot hear people taking. I do not think many listen above 80dB SPL.
Edits: 05/16/21
A live rock concert peaks at more than 120 dB SPL. A live orchestra is typically 100-110 dB SPL. Many people enjoy listening at live or near-live levels. That's why large home amps became so popular following the market shift to low-efficiency, infinite baffle speakers in the '60s. Amplifiers capable of 100w/ch and above were commonplace in people's homes. 45w/ch receivers were a compromise for folks who didn't want to spend so much or who weren't interested in the complexity of separate components. And FWIW, 92-95 dB SPL is commonly referred to as a medium-sensitivity speaker. High sensitivity is usually considered to be 100 dB or better.
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Buy Chinese. Bury freedom.
"Many people enjoy listening at live or near-live levels"
Listening at 95db for more than a few minutes at a time will cause permanent hearing damage. Maybe that's why high powered amps are so popular?
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
"Listening at 95db for more than a few minutes at a time will cause permanent hearing damage. "
Right. That's why live symphony concerts are illegal now.
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Buy Chinese. Bury freedom.
.
Have Fun and Enjoy the Music
"Still Working the Problem"
"A federal study finds that about a quarter of people between the ages of 20 and 69 who think their hearing is good or excellent are in fact showing signs of hearing loss."
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
LOL, they had to include people 69 years old to come up with a figure they could report as significant. None of this (nor the chart in your other post) changes anything I said about speaker sensitivity or amplifier power. The ratio between average and peak power in most music is considerable, and it requires a large amplifier to prevent clipping. That's particularly true when the speakers are only 87 dB SPL.
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Buy Chinese. Bury freedom.
Tre' is right concerning SPL's and hearing damage. Age is a factor if hearing is not protected from an early age and damage accumulates. House vacuums, chain saws, grass cutters, you name it. Just holding the phone to your ear can be loud with the wrong settings. My wife's phone settings are too loud for me when I get on it and I know she has damage.
I have not heard of any orchestra's being outlawed so maybe you should explain that statement. If anything should be monitored it would especially be rock concerts, but anything with live drums and cymbals can cut your head off if you're up close. If you don't bring hearing protection to a wedding reception your asking for trouble. Driving down the road with the window down and a Harley coming toward you is loud and annoying also. Damage? I don't know and I'm not waiting for the study.
And I would say anything greater than 85, 90 db is the threshold to be wary of, why argue different human evolutions?. The ears are tolerant of an increasing level to that db level. If you start your early mornings with 85db vacuums you need a new life.
Yes but the average listening level makes all the difference.
What would you say is your average listening level?
Mine is about 85db.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
"Listening at 95db for more than a few minutes at a time will cause permanent hearing damage."
That is only true for some people. Some ears are tougher than others. Just like one person gets kicked across the room and doesn't even bruise, while it would almost kill another.
"That is only true for some people. Some ears are tougher than others."
When the sounds gets too loud our ears "shut down" as a defense mechanism.
Some ears have already been damaged and are in permanent "shut down".
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Safe 80dB SPL is listening at 8 feet distance. 15 to 30 feet listening level at 90dB speaker output does not damage ears like in an outdoor house party with music playing.BTW- Tre is special. He has cast iron ear drums.
Edits: 05/17/21
I agree 90dB to 95dB SPL is dangerous to your hearing. 80dB SPL is IMO the maximum safe limit. Manufacturing plants that follow OHSA requirements limit noise exposure to 80dB SPL.
This is about musical peaks, not industrial machinery. Not the same.
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Buy Chinese. Bury freedom.
It is about safety. Has nothing to do with music peaks or anything else.
If you think it's about safety, you're on the wrong Website. This site is about vintage equipment, and that includes dozens, maybe hundreds, of amplifiers capable of power in excess of 100w/ch. If you think that's dangerous, don't buy one.
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Buy Chinese. Bury freedom.
An ear is an ear. Tre apparently likes to argue. Despite what Tre states, protect your ears.
My post was how to get 'in the door' with a great sounding vintage receiver for around $500 to $600 after a rebuild for reliability. I also offered three good sounding receivers if the buyer had deeper pockets.
100 watts or higher in a working vintage receiver will cost at least $750 for sub-brands. The Pioneer and Marantz are over $1000. Then, you have to have the receiver rebuilt at another $500. I think most would pass and buy a new amplifier at that cost.
A friend let a KR-8050 go too low for under your 750 somewhere and it had been partially restored, all but the power boost or something.
Yes most would pass but there is enough desire to own a marantz folks will pay absolutely stupid money for them. With all the free money around these days it is a great time to be dumping restored vintage gear.
Hi Sony, that was a lot of work you did, thanks.What I might ask about vintage stuff is how important is the wall outlet voltage using vintage equipment today.There is a guy on ebay who sells this outlet style box which drops todays voltage to 117 volts where you plug it in instead of 120 and up as it is today, in Maine anyway. Any of you guys got an idea on that? Does it matter? Thanks...Mark Korda
117 to 120 volts is no big deal for solid-state equipment. Even 117 to 125 volts is ok. I heard some places have as high as 128 volts during off peak hours.115 volt tube equipment with a voltage doubler maay be a little questionable at around 122 volts and higher. It would increase the power tube voltages from 400 volts to about 425 volts at 122 volts line voltage.
Edits: 05/16/21
That's not how you measure power in an audio amplifier. A 20W amplifier will reach maximum power at 20W. That is simply the science: the amplifier reaches maximum power and distortion reaches about 5%. If you are discussing a 1970s or 1980s solid state device, then distortion will be really ugly. If this is a tube amp, then distortion will be fairly benign at first and gradually become more noticeable.
So to measure distortion, you will need a dummy load (generally 8r or 16r), signal generator, and an oscilloscope. Inject a sine wave into the unit under test and increase the input voltage until you see distortion on the 'scope that is parallel to the load. The point where you see the signal start to distort will be about 5% distortion, mostly 2H distortion, but 3H will also increase. Reduce the input voltage until there is no visible distortion and measure the output voltage level across the load and use Ohms law to determine power. Measure the input voltage and that will give you the input sensitivity.
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