And also allows more current to flow through the output stage when the load demands that current.
This undersizing of the PSU is often used to prevent the amplifier output stage from blowing up.
This undersizing of the PSU is often used to prevent the amplifier output stage from blowing up.
I had to say that when i made my experiments with big caps i used a new 35A bridge (i don remember precisely the A but they were a lot ... even 40)
I remember that after switching off the amp (it did not have a relais on speakers) it went on with music for almost half a minute ...
I like the sound better than with the original smaller caps
and this is what I would do
But I wonder if the real and most impacting issue are the current limiting circuits
They are a dramatic bottleneck
I know that there are amps without any current limiting circuits
They are more dangerous, but if the reward is a nicely dinamic sound i would happily take the risk. For sure. Anytime 😉
Thanks and regards,
gino
So you would discourage any attempt of upgradind commercial amps ? 🙄
Maybe it would be just a "Therapeutic obstinancy" ? 🙁
Ok. But as i see in some amp a soft clipping i would like to see a switch for protection on/off.
There must be a better way to protect an amp than castrate it 😡
Because some commercial amps can give more. I feel it.
Regards,
gino
Only if there were a specific and verified problem to be addressed, and with an understanding of the consequences- which means understanding the unit at least as well as the original design engineer and the ability to measure before and after to verify that the "upgrade" actually has the intended effect.
Thank you very much !
I did not know but suspected this
And when a little amp with no protection but nice power supply comes out become a classic ...
But I feel that some very good ones are indeed "castrated" by design.
An expert eye can spot this just looking at the schema
Not my eye of course.
Thanks and regards,
gino
I understand. Not at all a task for beginners.
It would be nice that, anyway, they state the max current delivered by the amp, even on a pure resistive load ... like 8 ohm.
Just to understand what the amp is capable of.
An italian magazine do this kind of measurements.
And this one is the graph of a good and powerful amp (i.e. Harman Kardon HK990)
the more vertical the curve the better the amp at delivering current
Thanks and kind regards,
gino
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Look at The Audio Critic's PowerCube measurements to see that sort of thing being done correctly, accounting for reactive loads.
If you were designing an amp, you'd have to balance a number of "compromises" going from suppliers to electronic design, external appearance and reliability. Different designers have different ideas about each factor, but under-powering the transformer is a very convenient way to reduce costs and to protect (kind of...) the amplifer giving an smaller output power.
Anyway, if you consider that the music has a dynamic range of at least 6dB (loudness war) and if you don't want distortion in the sound, the maximun mean power you can get from your amp is about (or less than) 1/4 the maximun it can provide, so a smallish transformer is not such a bad idea assuming the PS caps has the right value to provide "the peaks" when they are needed.
Let me guess: you and your friend knew which pot was in circuit?ginetto61 said:
Switched attenuators present a dilemma to some people, as DC must be excluded to eliminate clicks. Do they choose 'evil potentiometers' or 'evil coupling caps'? The ohmophobe meets the faradaphobe. Who will win? Adopting a DC servo is not so good and can't be done by silicophobes.
I'm sorry... for the first time in years, I actually laughed so hard, I fell out of my chair. The people here at "work" think I'm nuts. (Maybe they're not wrong)
ohm-o-phobe and farad-o-phobe!!! That got the chuckle, but then to follow it with silic-o-phobes just took me over the edge. Wonderful! You've managed to capture, in 3 coined words, the major poles of the "audio debate", and the remarkable degree of mendacity in each camp that comes to play.
Of course, once one matures out of a particular camp (because it is so easy to become the butt of japes and jibes from the other camp tuts), the only natural thing is to become an opinionated panglossian. Kind of a Buddhist-of-the-various-methods. Or, you become a non-dogmatic, science-minded, "show me" kind of designer that believes in little, and expects a whole lot. Maybe even this is a continuum.
Sally forth, DF96. I'll continue to enjoy your posts.
GoatGuy
Hi ! found !
An externally hosted image should be here but it was not working when we last tested it.
Thanks !
Regards,
gino
Of course. You mean that we were influenced by this ?
It is true ,,,, there are clicks indeed.
But once that the volume is set i do not go on changing level.
If i feel this need there must be something wrong in the sound.
As i said once the level is set i keep it during all the listening.
For me one problem for pots is in the contacts quality
I have the feeling that the contact in an attenuator is so much better than in a pot especially those with plastic film
I opened one alps blue to see how it is done
The plastic film can deform.
I would like to try cermet pot where the resistive element, if i am not wrong, is on a ceramic substrate
For me the cermet pots, the good ones, could give great results (I think)
And i even prefer linear faked to log ... but i should try to be sure
Problem is that usually they come single and not dual
Thanks,
gino
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how can i blow bjts that can be found in much more powerful amps ? 🙄
If i had to choose i would use these anyway
Transistor bipolari | Transistor bipolari – Vendita online di Discreti| RS Components
even for a 30+30W amp. Just to stay on the safe side
And no protections at all.
I want to see the transformer sweat 😡😀
On the transformer side i know that the better ones can stand even a short circuit in the secondaries, so they are robust
then a mighty diodes bridge like a 40A ....
two caps of the serious one ,,,,
what could break first ?
Regards,
gino
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I'm a car guy so I will use that as an analogy.
My neighbor (no kid) has a super hot rod Subaru Imprezza. No slouch right off the showroom floor, it had 260 horse right out of the box (now they have 300 horse 😀 ). He built that thing up to the max. He had custom heads, custom cams, custom clutch, custom pistons, turbos big enough for a tractor-trailer, custom wastegate, etc. It dyno'd at 710 horse 😱.
The car was legendary at the track. It ran 10 second quarter miles all day long. Nobody could touch him with 710 horse in a tiny AWD car.
First he broke the transmission. So he has one custom built $$$$$$. Then he bent an axle; no alternatives there so he replaced all 4 axles and the driveshaft $$$$$. Then he split the block right down the middle and had a beefier block built $$$$$. Then he broke that block and had another one put in $$$$$. Then he sold it.
Meanwhile I had the Hot Rod Lincoln. It came stock with 225 horse. I built it up to 350 horse and built a custom transmission. It only runs 13.5-14 seconds in the quarter, but I can drive it to and from the track. In fact, I can drive it to the grocery store too. 10 years and 40,000 miles later and it's still running as good as day one. I haven't broken anything.
I used to drive it to the track, run a few quarter miles, and drive it home and help him fix his Subaru.
My neighbor (no kid) has a super hot rod Subaru Imprezza. No slouch right off the showroom floor, it had 260 horse right out of the box (now they have 300 horse 😀 ). He built that thing up to the max. He had custom heads, custom cams, custom clutch, custom pistons, turbos big enough for a tractor-trailer, custom wastegate, etc. It dyno'd at 710 horse 😱.
The car was legendary at the track. It ran 10 second quarter miles all day long. Nobody could touch him with 710 horse in a tiny AWD car.
First he broke the transmission. So he has one custom built $$$$$$. Then he bent an axle; no alternatives there so he replaced all 4 axles and the driveshaft $$$$$. Then he split the block right down the middle and had a beefier block built $$$$$. Then he broke that block and had another one put in $$$$$. Then he sold it.
Meanwhile I had the Hot Rod Lincoln. It came stock with 225 horse. I built it up to 350 horse and built a custom transmission. It only runs 13.5-14 seconds in the quarter, but I can drive it to and from the track. In fact, I can drive it to the grocery store too. 10 years and 40,000 miles later and it's still running as good as day one. I haven't broken anything.
I used to drive it to the track, run a few quarter miles, and drive it home and help him fix his Subaru.
Did you engineer the amplifier?
How big are the heatsinks in the bigger amplifiers? What is the current gain of the output stage in the bigger amplifiers? What kind of protection circuitry in the bigger amplifiers?
There's more to it than bigger transformers and capacitors.
Do you understand safe operating area of transistors? If you come up to speed on that concept then you can answer your own question.
It reaches the point where it is more logical and cost effective to start with a blank sheet of paper.
I do not want to discourage you from experimenting and asking questions. I have done exactly what you are proposing with success. It did exactly what I wanted it to and exactly what you are trying to achieve. But I also added pusher and puller fans to the heatsinks that are modulated by the audio input level; the fans run at variable speed from zero to max speed. Three years later and it is still in service. But I fully expect that it could melt down at any time. Can you accept that?
I would like to remind you that you are arguing with engineers. We may be stubborn and myopic at times, but we have math on our side. 😛
Analogy received.
I will not touch nothing sane. You have convinced me
And to be honest i have already destroyed more than one amp in these experiments
No more silly ideas
Tanks for the advice.
Regards,
gino
I agree. It is better start from the design
And actually the layout itself is done in a way to avoid any mods
Better to redirect to another equipment with better specs
Unfortunately these measurements of the power cube are not that common
They are quite telling about the robustness of an amp PS
And they could show the weaknesses quite clearly
Thanks again
Regards,
gino
No, it is laid out like any consumer product. It is designed to be as cost efficient and ergonomic as possible. Everything is engineered to the nth degree nowadays. While you may not personally like this particular amplifier, it was engineered to provide the maximum performance with the least materials in the smallest package. Believe me, manufacturers don't waste anything.
Consumers products are nothing like DIY at all. The design objectives and available resources are totally different. You want to build an amplifier that you like, and they want to build an amplifier that thousands of consumers will like enough to cough up their hard earned cash for.
And what was the reason for their destruction? You have to answer that question first before you proceed.
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