DIY Purifi Amp builds

[PaulD]

The whole warm-up thing is easy to prove or disprove (my testing of this showed that it was the listener that "warmed up").

We can measure much more than we can hear. So:
- Turn amplifier on, wait one minute and measure it.
- Wait 30 minutes and measure it again.
- Compare the measurements.

The only time this made a difference with any amplifier I tested was a class A amplifier that took 15-30 mins to reach thermal stability and I could measure different performance across that time, but to be honest I doubt I could hear any difference after a couple of minutes.

 

[ChrisPa]

Well we have moved on to led light bulbs.....

Over 10 years a Purifi amp will use about 1350kWh. Here in Oz I think the price is about $0.25 /kWh, so about $330. So maybe not a high cost, but I think that misses the point somewhat. Its just wasteful and I would rather spend the extra maybe $250 to $300 it costs to keep it switched permanently on something else.

Depending on your local climate some of it may be "wasteful".

When your heating system is on, background energy consumption/heat generation from other devices is not wasteful, it's just another source of heat

 

[March Audio]

Depending on your local climate some of it may be "wasteful".

When your heating system is on, background energy consumption/heat generation from other devices is not wasteful, it's just another source of heat

Is this sarcasm? :

15 watts of heat will have zero effect in a room.

 

[Matias]

Is this sarcasm?

15 watts of heat will have zero effect in a room.

I think he means that in the winter, 15W of heat wasted on the stereo are 15W less heat needed to be generated by the central heating system of the house, so the total sum is zero, so no waste.

 

[March Audio]

I think he means that in the winter, 15W of heat wasted on the stereo are 15W less heat needed to be generated by the central heating system of the house, so the total sum is zero, so no waste.

That's exactly what I thought he meant. 15 watts from an amp has no heating effect in a room. It will have no reduction effect on what your heating system does.

 

[ChrisPa]

That's exactly what I thought he meant. 15 watts from an amp has no heating effect in a room. It will have no reduction effect on what your heating system does.

Of course it does. Don't focus on the 15W.
Any source of heat will have an effect on the heat requirement of the heating system in that room together with all the other sources of heat in that room.
You're an engineer; you know this.

Not relevant is how much of an effect this will have.
As it happens, having re-insulated my living rooms last year to current UK new build regulations, I have 2 radiators capable a maximum of only 1500W heat input into the lounge, but this is only relevant to the transient response of the system. Once at temperature each radiator separately controls itself. And yes typically only 1 radiator well then be cycling, and with about 10% of its output or so. With an external temperature of 5°C it takes about 40 mins for the room to drop by 0.5°C from 21/20.5°C.

So yes each 15W, and the 5W from each lightbulb does have an effect on the demand on the heating system.

There is a partial myth that anything that creates heat is wasteful. If you need heat then it doesn't matter what its source is, and in this condition that source of heat is not wasteful. What is important is a control system that recognises and accurately controls to a target temperature rather than some arbitrary random measurement on the wrong wall or in the wrong room.

Isn't negative feedback wonderful

 

[March Audio]

Of course it does. Don't focus on the 15W.
Any source of heat will have an effect on the heat requirement of the heating system in that room together with all the other sources of heat in that room.
You're an engineer; you know this.

Not relevant is how much of an effect this will have.
As it happens, having re-insulated my living rooms last year to current UK new build regulations, I have 2 radiators capable a maximum of only 1500W heat input into the lounge, but this is only relevant to the transient response of the system. Once at temperature each radiator separately controls itself. And yes typically only 1 radiator well then be cycling, and with about 10% of its output or so. With an external temperature of 5°C it takes about 40 mins for the room to drop by 0.5°C from 21/20.5°C.

So yes each 15W, and the 5W from each lightbulb does have an effect on the demand on the heating system.

There is a partial myth that anything that creates heat is wasteful. If you need heat then it doesn't matter what its source is, and in this condition that source of heat is not wasteful. What is important is a control system that recognises and accurately controls to a target temperature rather than some arbitrary random measurement on the wrong wall or in the wrong room.

Isn't negative feedback wonderful

Well I suggest when winter comes you do an experiment.

Don't turn your heating system on an try to heat your room with a light bulb and measure just how much the room temperature rises. I can assure you that you will freeze your nuts off and measure no increase.

Yes I'm an engineer which is why I know an amp dissipating 15 watts will have no effect whatsoever on room temperature. The losses are waaay more than this. Obviously so. Your analysis is ludicrously simplistic. Of course its relevant how much effect 15 watts will have.

Btw, why have you stated 1500w for your hot water radiators. It depends entirely on the water temp.

I have no interest in getting further into a stupid argument about this, you can beleive whatever you want, but for the rest of us a bit of common sense tells us all we need to know.

 

[ChrisPa]

Well I suggest when winter comes you do an experiment.

Don't turn your heating system on an try to heat your room with a light bulb and measure just how much the room temperature rises.

Yes I'm an engineer which is why I know an amp dissapating 15 watts will have no effect whatsoever on room temperature. The losses are waaay more than this. Obviously so. Your analysis is ludicrously simplistic.

I have no interest in getting further into a stupid argument about this, you can beleive whatever you want, but for the rest of us a bit of common sense tells us all we need to know.

Stupid?
Beware of arrogance. It's not nice from anyone.

Go and reread and think carefully. As I said - every source of heat: every 15W amp, every 5W light bulb has an effect - and a cumulative effect. Particularly in a Passivhaus spec building. My renovations were't at passivhaus levels but they're close. Think about the relevance of external temperature and insulation levels on the heat demand of the room. Think about what the total energy demand is in that room to sustain the temperature.

The heat output of a human body is nominally equivalent to a 100W incandescent light bulb. At night time, so with no solar gain, and with external temperatures ~14C or above, a single body will sustain the temperature in my lounge - 20-20.5C. Add all my 5W LED bulbs to my 15W amp and I've nearly got another human in the room. Each of those LED bulbs has even less of an effect than the 15W amp but each one adds to the to the overall energy input.

Your lack of adding all the heat sources together and your lack of understanding of modern insulation standards is unfortunately simplistic.

 

[Matias]

Problem is in the summer, with AC turned on, all the heat generated is double wasted as the AC needs to compensate it....

 

[goryu]

I have a friend with a super insulated home. In Wisconsin, in the winter, he can heat his home with the lighting in his home so yes, every watt counts in such a home. Not many live in a home in the US with this kind of energy efficiency so in practice, for most, 15W isn't going to make a significant difference.

 

[March Audio]

Stupid?
Beware of arrogance. It's not nice from anyone.

Go and reread and think carefully. As I said - every source of heat: every 15W amp, every 5W light bulb has an effect - and a cumulative effect. Particularly in a Passivhaus spec building. My renovations were't at passivhaus levels but they're close. Think about the relevance of external temperature and insulation levels on the heat demand of the room. Think about what the total energy demand is in that room to sustain the temperature.

The heat output of a human body is nominally equivalent to a 100W incandescent light bulb. At night time, so with no solar gain, and with external temperatures ~14C or above, a single body will sustain the temperature in my lounge - 20-20.5C. Add all my 5W LED bulbs to my 15W amp and I've nearly got another human in the room. Each of those LED bulbs has even less of an effect than the 15W amp but each one adds to the to the overall energy input.

Your lack of adding all the heat sources together and your lack of understanding of modern insulation standards is unfortunately simplistic.

It's not the 100 watts from your body maintaining the temperature in your room it's the release of heat from the house structure.

15 watts is utterly insignificant.
Mass of air in a room 5x4x3m =72kg
Specific heat capacity of air=1003j/(kg*k)
So 200 watt hours to raise this by 1 deg.
So 13.5 hours to raise by 1 deg assuming 100% efficiency, no losses which is obviously not possible.

Your central heating system will be consuming kW of energy. It will not have any ability to control down to a 15 watt level even if this was a heat input that made a difference. The amps heat output will have no appreciable reduction in the energy consumed for heating.


I will not reply to you further on this off topic fantasy.

 

[barrows]

Your system simply wont be in use "all the time". Highly surprised if it is used more than 12 hours a day.

Do you have a need to contradict everything I say? As mentioned, I work from home. My system is playing music most of the time, except when I am sleeping. I play music first thing in the morning when I get up-so the system needs to have been on overnight to sound its best. It is playing most of the day/evening, sometimes as background music (often with Roon radio), and sometimes for close listening. I think I know how much time my system is playing music better than you. An occasional re-cappng is not a big deal for me, in fact, it is likely that I might get a new amplifier every 10 years or so anyway, given the rate at which my system changes, so cap life is not a problem for me with reasonably engineered gear.

If you prefer to turn off your system, I am fine with that, do whatever you like. Considering that I work from home, I am quite satisfied that my electrical footprint is quite moderate. I have yet to find any LED light bulbs which give a satisfying quality of lighting, although I often try new ones. I use a mixture of LED, Halogen, and Fluorescents here (in the US we can still choose the bulbs we prefer).

 

[LondonLad]

The VTV board is for folks that want to do opamp rolling.

I too stumbled across the "VTV" Purifi amp during a recent Google search. Would I be correct to believe that its primary differentiating characteristic is that one can use it to "roll opamps" should one choose, or not, IOW still be able to get it to function as a Purifi-Hypex only unit assembly? I don't have any desire to go down a rolling rabbit hole but I'm always open to hear how others feel about that capability.

 

[JimM]

Gentlemen: Please can we get back to comments on the subject of the forum rather than arguments about one’s personal preferences, my preference may not be the same as yours. I have been involved with audio for more than 60 years and have designed and used both linear and digital equipment for better than 50 years. Of course, all linear devices change with temperature both positive and negative from their off state that is a fact, this also true of most passive devices, but to lesser extent. This is why a designer of said equipment accounts for those changes in their design, or should. If one perceives an improvement after a component warms up, so what. March it seems every where you start posting it becomes an argument which I find strange for a manufacturer of equipment that sell to the people you are arguing with. NTC (thermistor) for those who want to know, a resistor with a negative temperature coefficient so that resistance decreases with increasing temperature, there are also PTC thermistors that are the opposite. By the way if your power supply has one keep your hands off as they can get quite hot. As to turn on surge it is more an issue here in the U.S. with 110 to 120 VAC than it is in the U.K. or Australia with 230VAC half the voltage double the current, unless they have repealed OHM’S since I went to school. If you want to see problems with tun on-surge hook up a current and voltage scope probe to the various point in a power supply and down stream to the other components. Now having said that a proper designed supply takes this into account with the components that are designed in or they should. I power down my equipment except the mentioned tube pre amp that keeps the filaments active hence the turn/off via remote or front switch on my PURIFI build, but I still find it improves after around 30 minuets of warm up, at least this is MY perception. You mentioned a blind test of significant differences due to warm up, how do you keep the equipment from warming if it is on? Then you said HYpex performance degrades as the components warm up, so this must mean the components are changing in some temperature dependent way. All I am trying to get at is if you as an owner of a piece of equipment and perceive or prefer your equipment to be left on so be it, you are the one responsible for energy cost or the repair bill as a result. In the case of class D amps, I don’t think 14 watt is going to make much difference. If that is the case maybe we should all wear insulated clothing as we enjoy our audio equipment. As we as average human beings heat up our soundings at 330 to 350 BTU / hour or the equivalent to 100watt light bulb, that is unless we are at room temperature for a long extended time, in which case we are not listening to anything. Please let’s get back to enjoying our forum.
JimM

 

[March Audio]

Do you have a need to contradict everything I say? As mentioned, I work from home. My system is playing music most of the time, except when I am sleeping. I play music first thing in the morning when I get up-so the system needs to have been on overnight to sound its best. It is playing most of the day/evening, sometimes as background music (often with Roon radio), and sometimes for close listening. I think I know how much time my system is playing music better than you. An occasional re-cappng is not a big deal for me, in fact, it is likely that I might get a new amplifier every 10 years or so anyway, given the rate at which my system changes, so cap life is not a problem for me with reasonably engineered gear.

If you prefer to turn off your system, I am fine with that, do whatever you like. Considering that I work from home, I am quite satisfied that my electrical footprint is quite moderate. I have yet to find any LED light bulbs which give a satisfying quality of lighting, although I often try new ones. I use a mixture of LED, Halogen, and Fluorescents here (in the US we can still choose the bulbs we prefer).

When it's demonstrably wrong I will offer an alternative view.

I assume you sleep so your system is not being used 24 / 7.

It does not need to be on all night to sound its best.

If you want to waste time and money recapping your amp when turning it off would have prevented the need, saved you money and benefitted the environment, that's up to you. However it seems pretty silly to me.

Led light bulbs are readily available that match the colour temperature of halogen or standard tungsten filament lamps. Or indeed cooler daylight. Compact Flourescent lamps OTOH are hideous flickery abominations.

 

[JimM]

By the way my wife and I are going to do a amplifier shoot out with what we have in house, which is the following:
1. Mark Levison 585 integrated.
2. Benchmark DAC2 HGC as preamp and our EVAL1 Purifi build.
3. Benchmark DAC2 HGC as preamp and our Bryston 3B.
Speaker are Magnepan 1.7 and Jeff Bagby - Kairos- Satori three with TW29R ring dome tweeter, Satori-MW16P-8 6.5in mid/woofer, SB 29NRX75-6- 10in woofer.
OppO BD95 DVD blu-ray player as cd transport, Manley Chinook phono pre Clearaudio Concept with Dynavector20X2L mc.
All cables remain the same with the exception of balanced from DAC to PuriFI and Byston.
All gear will have min 30 minute warm up before sessions, the biggest problem is level matching between sessions but will do our best.
program material around a hour of mix of music per cd, and cuts from three different record albums. Understand this will be just our impressions, but my wife has very good ears.
JimM

 

[JimM]

Thank you March for your comments.
JimM

 

[March Audio]

Gentlemen: Please can we get back to comments on the subject of the forum rather than arguments about one’s personal preferences, my preference may not be the same as yours. I have been involved with audio for more than 60 years and have designed and used both linear and digital equipment for better than 50 years. Of course, all linear devices change with temperature both positive and negative from their off state that is a fact, this also true of most passive devices, but to lesser extent. This is why a designer of said equipment accounts for those changes in their design, or should. If one perceives an improvement after a component warms up, so what. March it seems every where you start posting it becomes an argument which I find strange for a manufacturer of equipment that sell to the people you are arguing with. NTC (thermistor) for those who want to know, a resistor with a negative temperature coefficient so that resistance decreases with increasing temperature, there are also PTC thermistors that are the opposite. By the way if your power supply has one keep your hands off as they can get quite hot. As to turn on surge it is more an issue here in the U.S. with 110 to 120 VAC than it is in the U.K. or Australia with 230VAC half the voltage double the current, unless they have repealed OHM’S since I went to school. If you want to see problems with tun on-surge hook up a current and voltage scope probe to the various point in a power supply and down stream to the other components. Now having said that a proper designed supply takes this into account with the components that are designed in or they should. I power down my equipment except the mentioned tube pre amp that keeps the filaments active hence the turn/off via remote or front switch on my PURIFI build, but I still find it improves after around 30 minuets of warm up, at least this is MY perception. You mentioned a blind test of significant differences due to warm up, how do you keep the equipment from warming if it is on? Then you said HYpex performance degrades as the components warm up, so this must mean the components are changing in some temperature dependent way. All I am trying to get at is if you as an owner of a piece of equipment and perceive or prefer your equipment to be left on so be it, you are the one responsible for energy cost or the repair bill as a result. In the case of class D amps, I don’t think 14 watt is going to make much difference. If that is the case maybe we should all wear insulated clothing as we enjoy our audio equipment. As we as average human beings heat up our soundings at 330 to 350 BTU / hour or the equivalent to 100watt light bulb, that is unless we are at room temperature for a long extended time, in which case we are not listening to anything. Please let’s get back to enjoying our forum.
JimM

Jim

This forum is about science, if people post fantasies about an amp dissipating 15 watts heating their room then they will get presented some scientific information which shows them why it's not the case.

The information provided about cap life is just that, information. What people choose to do with that is up to them

This simply isn't about preference. .

Equally this is the same with people's opinions about sound quality changing. People simply make inaccurate judgements. If this web site has any message to convey, that is it. That's precisely why blind tests are performed.

Amir has made a number of measurements of performance of components during warm up. The change is very small and often non existent, yet people will claim they hear differences. This is not saying there are no performance changes, but in well designed (solid state) equipment it is very small, so small it's very unlikely to be audible.

Also, as I mentioned, people shouldn't assume the performance gets better after warm up. It is interesting and telling in itself that people always claim an improvement in sound after warm up.

Finally, there is one comment that my customers repeatedly make to me, they thank me for having a no BS approach contrary to the usual hifi sales marketing nonsense or other simply inaccurate information, myths and beliefs. People who believe all the typical hifi marketing nonsense, myths and beliefs are (generally) not my market.

 

[March Audio]

By the way my wife and I are going to do a amplifier shoot out with what we have in house, which is the following:
1. Mark Levison 585 integrated.
2. Benchmark DAC2 HGC as preamp and our EVAL1 Purifi build.
3. Benchmark DAC2 HGC as preamp and our Bryston 3B.
Speaker are Magnepan 1.7 and Jeff Bagby - Kairos- Satori three with TW29R ring dome tweeter, Satori-MW16P-8 6.5in mid/woofer, SB 29NRX75-6- 10in woofer.
OppO BD95 DVD blu-ray player as cd transport, Manley Chinook phono pre Clearaudio Concept with Dynavector20X2L mc.
All cables remain the same with the exception of balanced from DAC to PuriFI and Byston.
All gear will have min 30 minute warm up before sessions, the biggest problem is level matching between sessions but will do our best.
program material around a hour of mix of music per cd, and cuts from three different record albums. Understand this will be just our impressions, but my wife has very good ears.
JimM

Match volume levels by playing something like a 100Hz tone and measuring the voltage at the speaker terminals. Level matching is of critical importance and won't be accurate at all if done by ear and not accurate enough if measured with a sound level meter.

I think you know what I would say about the efficacy of sighted tests.

 

[JimM]

Thank you March for your input.
JimM