Hi, everyone!
This is my last resort, as I searched and asked everywhere else and no one could really help me with this.
I am browsing for an integrated amplifier and I stumbled upon the Onkyo A-9150, that meets all my requirements (budget, good sound, discreet class AB design, internal DAC, pre-out, phono, the whole package), but I am really curious by its power rating. Looking at the specs, it is rated as 30W/8-ohm and 60W/4-ohm with 0.08% THD from 20 to 20,000Hz.
Okay, but the manual also states that it weighs 9.2 Kg, almost the same (even heavier) as the Yamaha A-S301, that weighs 9.0 Kg. Only the Yamaha is rated as 60W/8-ohm with 0.019% THD and 70W/6-ohm with 0.038% THD from 20 to 20,000Hz.
Upon inspection of pictures over the internet, their transformers are pretty much identical, just like their chassis. Also, the Onkyo has two 10,000 uF capacitors, and the Yamaha two 6,800 uF caps. I am definitely no expert, but for what I have seen in the service manual (very superficially), the power supplies seemed very similar to me. And the voltages indicated in the power amplifier section were 40 V for the Yamaha A-301 and 37.5 V for the Onkyo A-9150. I don't know if that difference is significant to that point.
How come is this difference in power so big? Where is all the power in the Onkyo unit going, if not the speaker output? Any ideas?
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PS.: If you look in their service manuals, I guess you will find that their topology is similar and that the Onkyo A-9150 amplifier transistors are even more powerful than the Yamaha A-S301's. I also noticed that the idling current adjustments are different: the Yamaha asks for 1-10mV on the emitter resistor, while the Onkyo asks for 20-30mV. Maybe there's something in that, but I just don't know enough to make something of this.
Onkyo A-9150 Service Manual
Yamaha A-S301 Service Manual
This is my last resort, as I searched and asked everywhere else and no one could really help me with this.
I am browsing for an integrated amplifier and I stumbled upon the Onkyo A-9150, that meets all my requirements (budget, good sound, discreet class AB design, internal DAC, pre-out, phono, the whole package), but I am really curious by its power rating. Looking at the specs, it is rated as 30W/8-ohm and 60W/4-ohm with 0.08% THD from 20 to 20,000Hz.
Okay, but the manual also states that it weighs 9.2 Kg, almost the same (even heavier) as the Yamaha A-S301, that weighs 9.0 Kg. Only the Yamaha is rated as 60W/8-ohm with 0.019% THD and 70W/6-ohm with 0.038% THD from 20 to 20,000Hz.
Upon inspection of pictures over the internet, their transformers are pretty much identical, just like their chassis. Also, the Onkyo has two 10,000 uF capacitors, and the Yamaha two 6,800 uF caps. I am definitely no expert, but for what I have seen in the service manual (very superficially), the power supplies seemed very similar to me. And the voltages indicated in the power amplifier section were 40 V for the Yamaha A-301 and 37.5 V for the Onkyo A-9150. I don't know if that difference is significant to that point.
How come is this difference in power so big? Where is all the power in the Onkyo unit going, if not the speaker output? Any ideas?
-------------------------------------------------------------------------------------
PS.: If you look in their service manuals, I guess you will find that their topology is similar and that the Onkyo A-9150 amplifier transistors are even more powerful than the Yamaha A-S301's. I also noticed that the idling current adjustments are different: the Yamaha asks for 1-10mV on the emitter resistor, while the Onkyo asks for 20-30mV. Maybe there's something in that, but I just don't know enough to make something of this.
Onkyo A-9150 Service Manual
Yamaha A-S301 Service Manual
Are both specs the average power while continuously playing sine waves or is the Yamaha spec a music power, peak power, peak envelope power or whatever manufacturers come up with to get higher numbers power spec? Are both specs at low distortion, or is the Yamaha spec for 10 % THD?
Power output is relatively unimportant, considering at normal listening leves, you rarely need more than one watt.
Lacking norms how to precisely measure output power, it's no surprise that similar amps are rated completely differently.
Not that there are no norms, but there is no authority to inforce them.
Remember the days when small boomboxes powered by six batteries has sticker claiming 2x120 watts?
Lacking norms how to precisely measure output power, it's no surprise that similar amps are rated completely differently.
Not that there are no norms, but there is no authority to inforce them.
Remember the days when small boomboxes powered by six batteries has sticker claiming 2x120 watts?
OR 😉 they could simply be lying re specs.
Not too many years ago Ford Mustangs actually produced more than 100Hp less than their specs claimed.
OR how Yamaha R6 motorcycles of ~2006 had a claimed (and heavily advertised) redline of 16000 Rpms.
Subsequent independant testings revealed they only managed 13000 and the Tach software had been altered to read 16 K at an actual 13 K.
Not too many years ago Ford Mustangs actually produced more than 100Hp less than their specs claimed.
OR how Yamaha R6 motorcycles of ~2006 had a claimed (and heavily advertised) redline of 16000 Rpms.
Subsequent independant testings revealed they only managed 13000 and the Tach software had been altered to read 16 K at an actual 13 K.
A manufacturer can rate their amplifier under any test conditions they specify - as long as the conditions comply with retail laws in the country of sale. So if a manufacturer is facing stiff competition from others, all they need do is specify different conditions where their product looks significantly better. That won't suit all customers but they are looking for market percentages, after all.
If you think about the power specs, the Onkyo model has exactly double power at 4R loads compared to 8R. That's highly unusual with class AB unless the issue is that it has comparatively low power supply rail voltages. On the other hand, Yamaha's model delivers only 17% more power with a 6R load and isn't even specified for 4R. I suggest the difference here is primarily with the power supply voltages. The relative size of the transformers probably has less to do with this.
If you think about the power specs, the Onkyo model has exactly double power at 4R loads compared to 8R. That's highly unusual with class AB unless the issue is that it has comparatively low power supply rail voltages. On the other hand, Yamaha's model delivers only 17% more power with a 6R load and isn't even specified for 4R. I suggest the difference here is primarily with the power supply voltages. The relative size of the transformers probably has less to do with this.
The Yamerhammer has an "impedance" switch which re-taps the power transformer to optimize for 4r or 6r loads. The Onky (like 98% of amps) uses one transformer which must be a compromise.
Rough numbers squinted, guesstimated, and interpolated from incomplete data in service manuals:
Onk 9150
rails: +/-37V
max gross power: 55W@8r
Yam 301
rails: +/-38V@4r or +/-46V@6r
max gross power: 84W@8r(on 6r tap)
Rough numbers squinted, guesstimated, and interpolated from incomplete data in service manuals:
Onk 9150
rails: +/-37V
max gross power: 55W@8r
Yam 301
rails: +/-38V@4r or +/-46V@6r
max gross power: 84W@8r(on 6r tap)
Thanks to your high-res. image, it's now possible to see a few voltages. PRR had to squint and guess what the text on the linked manual showed. Anyway, the point is that Yamaha uses a higher voltage tapping on a similar size transformer and this allows much more efficient 8R speaker use whilst still being capable of 6R use. The original NAD 3020 models had this feature too, many years ago. On the downside, it's likely that the Yamaha model will current limit and distort if 4R speakers are used at a high enough level. It isn't even specified for 4R use.
This is also called specsmanship - the art of quoting only the mandatory and attractive performance figures of your product, knowing that the rest are either mediocre or poor by comparison.
This would not seem to be a problem for home use but it really is with low cost speakers built today. Most are specified as 6R or 8R but in fact, are more like car speakers at 4R and this enables them to sound better and sell better because they play louder at the same settings and are more impressive but they still require much more current. I think this is where the Onkyo model will have a decided edge.
This is also called specsmanship - the art of quoting only the mandatory and attractive performance figures of your product, knowing that the rest are either mediocre or poor by comparison.
This would not seem to be a problem for home use but it really is with low cost speakers built today. Most are specified as 6R or 8R but in fact, are more like car speakers at 4R and this enables them to sound better and sell better because they play louder at the same settings and are more impressive but they still require much more current. I think this is where the Onkyo model will have a decided edge.
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> PRR had to squint and guess
The '301 has a big brother, the '501, rated twice the power. My squint suggests the 33V/40V numbers are for the '501, the '301" "should" have lower rails.
Some funny business may be involved. When a maker has a series of models, it is not unknown to down-rate the lower model so as to not compete so much against the higher model.
Still very odd. The '301 sells for $350, the '501 for $550. This comes to $200 for another 60 Watts. It is insane to charge $3/Watt for incremental power in this day and age. (We passed $1/W in the 1970s, and I have seen $0.20/W recently.) For what is not an exceptional circuit technically (no CAT-SIT devices, no Pentagram topology, no multi-servo correction-loops...).
The topic of weight has been mentioned. Yes, I have judged amplifiers "by weight". I once owned one of the heaviest 20W/ch amps ever mass-produced. But the makers know this game too. And they can play it to their advantage. Buy bumper-iron or frame-iron to make the housing. (I have seen other products with Zinc or Lead weights added for heft.) Use barn-roof iron for transformers instead of proper electrical steel. You need twice as much but it may be less than half the price per ton.
The '301 has a big brother, the '501, rated twice the power. My squint suggests the 33V/40V numbers are for the '501, the '301" "should" have lower rails.
Some funny business may be involved. When a maker has a series of models, it is not unknown to down-rate the lower model so as to not compete so much against the higher model.
Still very odd. The '301 sells for $350, the '501 for $550. This comes to $200 for another 60 Watts. It is insane to charge $3/Watt for incremental power in this day and age. (We passed $1/W in the 1970s, and I have seen $0.20/W recently.) For what is not an exceptional circuit technically (no CAT-SIT devices, no Pentagram topology, no multi-servo correction-loops...).
The topic of weight has been mentioned. Yes, I have judged amplifiers "by weight". I once owned one of the heaviest 20W/ch amps ever mass-produced. But the makers know this game too. And they can play it to their advantage. Buy bumper-iron or frame-iron to make the housing. (I have seen other products with Zinc or Lead weights added for heft.) Use barn-roof iron for transformers instead of proper electrical steel. You need twice as much but it may be less than half the price per ton.
Having my own squint, I agree that even all the extra sound processing, monitoring etc features and probably a much better DAC in the '501 model, don't amount to that much more money. It seems almost certain that there is no impedance switch on the '301 and then it does add up that they would trade off 4R capability for healthy looking 8-6R ratings. I think that sort of compromise would likely limit its appeal though.
> limit its appeal though.
That's OK. Customer asks for the '301. After a demo, salesman says "it's a fine amp, however I'd like you to look at the '501, you get more power and doo-dads for not that much more money." The difference in commission will buy another round of drinks tonight.
That's OK. Customer asks for the '301. After a demo, salesman says "it's a fine amp, however I'd like you to look at the '501, you get more power and doo-dads for not that much more money." The difference in commission will buy another round of drinks tonight.
Expressing nonexistent physical relationships as simple quantitative ratios with procedures going far beyond the capability of mathematical language is a religious rather than a scientific endeavor, even though these notions have vague boundaries.
PRR, the by-weight technique for power estimation is much more reliable. I increasingly like your posts.
PRR, the by-weight technique for power estimation is much more reliable. I increasingly like your posts.
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