Member
Joined 2009
Paid Member
It's business, the cost of using the case as a heatsink is lower as now you not only avoid a dedicated heatsink but the rest of the chassis is easier too.
You know the answer to your own question of course.
Most people will not run their fancy hi-fi like it was a party rig. It'll be used at home on a fine wooden rack with nice speakers listening at relatively low power levels. Of course Naim will market that the amplifier can generate peak output levels equivalent to 60 W (or whatever) but it ain't going to be happy putting that out continuously.
I expect a fair bit of gear would fail the continuous use at high power scenario (and not just hi-fi) but designing for that means a lot more expense (size, weight etc.).
I can't tell off hand which Naim it is but 'east electronics' states it is 60W per channel. So 50% of that would be a total of 60W.
Also, I would agree with Bigun that the vast majority of customers are unlikely to be running their amp at 60W per channel continuously. The amps have thermal cut-outs in case they overheat.
I know that Naim run all their amps in a stressful burn-in for 24 hours or more before shipping.
I think there are reasonable opportunities to criticize Naim's products but I don't think overheating is one of them. 😎
Last edited:
Traderbam What is nice about this forum is that most members talk about facts not estimations
So NAim is the nait 5si and it speced to 60WPC
If you know which of the amplifiers mentioned above have thermal cut outs please inform me also since i have never seen one ....
As about the Magnum i really have no specs but of course i never said or expect anything in Class A
Finally sorry i don't get your point gents in case you are right specs should say for example 20W continuously and 60W maximum ...but between me and you if you spec that, nobody will buy your amp ....
If the amp is stated 60WPC it may as well needed to play so, farther more to produce that power for a period of time probably not every day but at least once in a while ...
So NAim is the nait 5si and it speced to 60WPC
If you know which of the amplifiers mentioned above have thermal cut outs please inform me also since i have never seen one ....
As about the Magnum i really have no specs but of course i never said or expect anything in Class A
Finally sorry i don't get your point gents in case you are right specs should say for example 20W continuously and 60W maximum ...but between me and you if you spec that, nobody will buy your amp ....
If the amp is stated 60WPC it may as well needed to play so, farther more to produce that power for a period of time probably not every day but at least once in a while ...
I don't know about the Naits...I don't have one in front of me. I know the NAP250 have thermal cut-outs. I would imagine all their separate amps have some form of over-heating protection even if the Naits do not.
Have you taken a Nait apart?
Have you taken a Nait apart?
To be accurate
A comercial Japanese amplifier ( Andrew this one is for you to read ) is made against electronics philosophy
Meaning 2 X TO220 semis are powered far above the normal of 35-40 volts often to 50 or 55 so this way in low power have extremely nice dynamics and plenty of headroom Then these are perfectly protected by proper Vbe multipliers and a VI limiter and often a very well calculated bandwidth .
Trafo is most of the time smaller than supposed to be so distortion will come quicker than expected and at the "rated " power of the amplifier things are expected to be very dirty
The only difference is that due to safety measures the result will be produced with safety amplifier at full power is expected to play bad but without safety issues ....
Hopefully countermeasures "do not act" in low power so you have a nice amplifier for every day use in low power which we all know that is partially true
My estimation is that if the Japanese didn't have a fetish with knobs lamps and function in audio machines the English audio factory should have never seen the light of sun ...
I was once present in a meeting and had a chance to meet one of the designers of Yamaha and i placed a question on him asking why Yamaha doesn't focus on machine that has far less functions than the average Yamaha far less knobs Just a selector and a volume control will do while the rest of the budget will be given in audio innovation and quality of sound built and so on ...
The answer was pretty simple "
We are so many years in the consumer audio so if we make step towards simplicity or half step towards HI End people will not believe us and it will take too long to re-establish Yamaha in that field also ...That ...doesn't sound so cost effective !!!
A comercial Japanese amplifier ( Andrew this one is for you to read ) is made against electronics philosophy
Meaning 2 X TO220 semis are powered far above the normal of 35-40 volts often to 50 or 55 so this way in low power have extremely nice dynamics and plenty of headroom Then these are perfectly protected by proper Vbe multipliers and a VI limiter and often a very well calculated bandwidth .
Trafo is most of the time smaller than supposed to be so distortion will come quicker than expected and at the "rated " power of the amplifier things are expected to be very dirty
The only difference is that due to safety measures the result will be produced with safety amplifier at full power is expected to play bad but without safety issues ....
Hopefully countermeasures "do not act" in low power so you have a nice amplifier for every day use in low power which we all know that is partially true
My estimation is that if the Japanese didn't have a fetish with knobs lamps and function in audio machines the English audio factory should have never seen the light of sun ...
I was once present in a meeting and had a chance to meet one of the designers of Yamaha and i placed a question on him asking why Yamaha doesn't focus on machine that has far less functions than the average Yamaha far less knobs Just a selector and a volume control will do while the rest of the budget will be given in audio innovation and quality of sound built and so on ...
The answer was pretty simple "
We are so many years in the consumer audio so if we make step towards simplicity or half step towards HI End people will not believe us and it will take too long to re-establish Yamaha in that field also ...That ...doesn't sound so cost effective !!!
Last edited:
According to Naim's web page, the NAP250 is rated at 80W pc 8 ohms. I understand from a thread in this forum that the psu rails are +/-40V. The max theoretical average sinewave power into 8 ohms is 100W. So Naim are underestimating if anything and using average power rather than peak. So by your reckoning, they have never sold any NAP250s? 😉
No not really they probably sold a lot based on the sound they produce though users luckily made it or hardly ever had to use the amplifier at full power for a long period of time
The ones that used the amp in full power are my clients ....😉😉😉😉
Last edited:
He he. You want them to fail! Well, I was walking around Thessaloniki last August and I nearly suffered a personal thermal cut-out. Lovely place. Seriously hot. Good for your business.
He he. You want them to fail! Well, I was walking around Thessaloniki last August and I nearly suffered a personal thermal cut-out. Lovely place. Seriously hot. Good for your business.
Imagine how things are just 500klm towards south in Athens or 1000klm south in Creta
Member
Joined 2009
Paid Member
You are forgetting that the amplifier will never be able to swing to the rails. An 80Wrms rating is consistent with roughly +/-36V achievable swing.
And never mind the heat, a little to south of us storm Niko is wreaking winter havoc!
At 1830 audio devices per year you are able to create and record statistics
We normally buy and change 25.000 electrolytic capacitors per year
Statistically most of them are used to vintage Japanese amplifiers
Any body wondered why ?
Cause these lived long enough to dry out their capacitors and come to the shop dirty tired and with their capacitors dried out but other than those in a working condition.
English made or English style made amplifiers come to the shop normally because are broken while their capacitors hardly ever need replacements either since these are not so old or haven't been used that much
Obviously capacitors are the same like Elna Rubicon , Nippon and so on except NAD that always used Teapo from Taiwan since day one
Now days quality of caps in some of them is total rubbish
We normally buy and change 25.000 electrolytic capacitors per year
Statistically most of them are used to vintage Japanese amplifiers
Any body wondered why ?
Cause these lived long enough to dry out their capacitors and come to the shop dirty tired and with their capacitors dried out but other than those in a working condition.
English made or English style made amplifiers come to the shop normally because are broken while their capacitors hardly ever need replacements either since these are not so old or haven't been used that much
Obviously capacitors are the same like Elna Rubicon , Nippon and so on except NAD that always used Teapo from Taiwan since day one
Now days quality of caps in some of them is total rubbish
Sugden A28 II is on my bench as we speak anybody cares to see how oscillation looks in a scope ?
Hence "theoretical". But I think it might just push 38V and 90W given the regulators. In any case, Naim claim realistic average sinewave power rather than some companies who might bandy peak power about. Or "music power" whatever that is...I mean, what else is it likely to be: hairdryer power? 😛
for example : even though the wiring looks pretty neat obviously this is not the better way to do it ....
Oh and by the way can somebody point to me where is the Vbe Multiplier in this circuit ? haven repair one and i can not see in the picture
Oh and by the way can somebody point to me where is the Vbe Multiplier in this circuit ? haven repair one and i can not see in the picture
Hi Sakis,
Like other early NAP boards, the Vbe multiplier is on the PCB, next to the bias setting pot. (just on the R side) Reading a little about Naim amplifiers and clones, we find that it takes a long time for them to warm up and bias to come to equilibrium because of that remote location.
Since it's a quasi-complementary design, the bias controller really has 2 temperature coefficients - one for the CFP driver, the other for the EF output transistor so it's difficult to design a controller and make bias current track properly by simply attaching it to either heatsink when neither is the correct point of temperature reference.
Luckily, it doesn't make a lot of difference even if bias doesn't track exactly but it would be more reassuring if it took less time to correct an unsafe trend. On later, single board models, the Vbe multipliers are flipped onto the copper side, where they are much closer to the bottom plate. On my NAP200 clone, the settling time is much reduced.
Like other early NAP boards, the Vbe multiplier is on the PCB, next to the bias setting pot. (just on the R side) Reading a little about Naim amplifiers and clones, we find that it takes a long time for them to warm up and bias to come to equilibrium because of that remote location.
Since it's a quasi-complementary design, the bias controller really has 2 temperature coefficients - one for the CFP driver, the other for the EF output transistor so it's difficult to design a controller and make bias current track properly by simply attaching it to either heatsink when neither is the correct point of temperature reference.
Luckily, it doesn't make a lot of difference even if bias doesn't track exactly but it would be more reassuring if it took less time to correct an unsafe trend. On later, single board models, the Vbe multipliers are flipped onto the copper side, where they are much closer to the bottom plate. On my NAP200 clone, the settling time is much reduced.
Member
Joined 2009
Paid Member
I don't think there's an issue with the quasi-output have two different temperature behaviours, you can choose one of them, i.e. whether to derive the bias servo from the CFP driver or the Darlington power device - so long as you control one of them the other will track because the nfb loop enforces zero dc-offset.
you could have written the same thing about British vs Japanese cars of the era.
you could have written the same thing about British vs Japanese cars of the era.
Hi Sakis,
I would say that they are using active current limiting. If you limit the current of the devices they cannot thermally runaway.
I would say that they are using active current limiting. If you limit the current of the devices they cannot thermally runaway.
Last edited:
Ian, this looks like it could be a DIY amplifier. To be honest, the heat sink would be big enough for dynamic music, maybe not steady state sinusoidal testing but who listens to single tones for any length of time.
It is pretty neat inside and smart idea of having the earthing bar between the two loudspeaker grounds.
It is an extremely practical design for a hand built production line, you can see the scribe markings for the drill holes mounting the amps. Someone sat thinking about the internal layout before just blundering on, the wiring harness is most likely made on a plinth with a few nails in it, that is why the corners are very square and neatly tied down.
The chassis is a U-shape and the case slips over it. It can be made using very simple tools, a guillotine and a small bending press and a drill-press, nothing more. The boards seem to be inhouse made using simple techniques and hand soldered. This is a company that probably started in someones garage and possibly even remained there with no more that maybe 10 people.
I am suitably impressed, it is well made, practical and very simple.
It is pretty neat inside and smart idea of having the earthing bar between the two loudspeaker grounds.
It is an extremely practical design for a hand built production line, you can see the scribe markings for the drill holes mounting the amps. Someone sat thinking about the internal layout before just blundering on, the wiring harness is most likely made on a plinth with a few nails in it, that is why the corners are very square and neatly tied down.
The chassis is a U-shape and the case slips over it. It can be made using very simple tools, a guillotine and a small bending press and a drill-press, nothing more. The boards seem to be inhouse made using simple techniques and hand soldered. This is a company that probably started in someones garage and possibly even remained there with no more that maybe 10 people.
I am suitably impressed, it is well made, practical and very simple.
Last edited:
- Status
- Not open for further replies.