Hi back,
Anything lower than about 220mA and you'll start to see an appreciable increase in high-order harmonics. These mosfets like bias current, and lots of it.
I would suggest that if you're looking for that much output power, then you should probably be looking at a tracking supply to go with this. Using a tracking supply would allow you to run the base rails down at +/-15-20V and really crank up the bias for great performance.
An undertaking like that isn't easy, but I know there are a few designs out there. When you start running Class AB at really high power, the cons really start to add up in a way that isn't manageable. Chances are if you need more than a few hundred watts then:
1. You're driving subwoofers, and might want to consider class D
2. You have extremely low efficiency speakers and like to listen really loud, in which case your speakers will be the dominant distortion contributer and it doesn't matter what amp you use (so you can use class D again)
3. You're into car audio, and you like to tell your friends "how many watts you got". In this case, I suggest just plugging the speaker directly into the mains outlet "for maximum watts". (I should clarify for our car audio enthusiast friends that this is just a joke)
Also keep in mind that the LME49830 has a maximum voltage of 100V, and I wouldn't suggest running it up that high. If you stick to a safer 90V, then your mosfet rails will be 80-85V and your output will swing to roughly 75-80V peak. That means even with several parallel devices, the most you can get into 8 ohms is about 400 watts. If you're driving a 4 ohm load, then you can certainly go higher with enough output devices.
These are all things to consider before you proceed. All amplifiers have their place, and it's important to pick the right one for the job. If you need less than 16 watts, it's hard to beat the LPUHP, and if you need less than 300 watts it's hard to beat this amp, but if you're going higher than 400 watts, then class D starts making sense, unless you can live with the very high idle dissipation of a class AB amp at those power levels.
Cheers,
Owen
Anything lower than about 220mA and you'll start to see an appreciable increase in high-order harmonics. These mosfets like bias current, and lots of it.
I would suggest that if you're looking for that much output power, then you should probably be looking at a tracking supply to go with this. Using a tracking supply would allow you to run the base rails down at +/-15-20V and really crank up the bias for great performance.
An undertaking like that isn't easy, but I know there are a few designs out there. When you start running Class AB at really high power, the cons really start to add up in a way that isn't manageable. Chances are if you need more than a few hundred watts then:
1. You're driving subwoofers, and might want to consider class D
2. You have extremely low efficiency speakers and like to listen really loud, in which case your speakers will be the dominant distortion contributer and it doesn't matter what amp you use (so you can use class D again)
3. You're into car audio, and you like to tell your friends "how many watts you got". In this case, I suggest just plugging the speaker directly into the mains outlet "for maximum watts". (I should clarify for our car audio enthusiast friends that this is just a joke)
Also keep in mind that the LME49830 has a maximum voltage of 100V, and I wouldn't suggest running it up that high. If you stick to a safer 90V, then your mosfet rails will be 80-85V and your output will swing to roughly 75-80V peak. That means even with several parallel devices, the most you can get into 8 ohms is about 400 watts. If you're driving a 4 ohm load, then you can certainly go higher with enough output devices.
These are all things to consider before you proceed. All amplifiers have their place, and it's important to pick the right one for the job. If you need less than 16 watts, it's hard to beat the LPUHP, and if you need less than 300 watts it's hard to beat this amp, but if you're going higher than 400 watts, then class D starts making sense, unless you can live with the very high idle dissipation of a class AB amp at those power levels.
Cheers,
Owen
hello owen.
my speakers are 87db and stable at 3 ohms.
i want to have headroom.
i already have good classd amp but this looks
better.
to make it more realistic i believe two pairs will give me
about 700watt at 3 ohms with 70 volt rails and 80volt
for the chip?
if yes i could live with that.
it will be dissipating about 60-70 watt per channel?
my speakers are 87db and stable at 3 ohms.
i want to have headroom.
i already have good classd amp but this looks
better.
to make it more realistic i believe two pairs will give me
about 700watt at 3 ohms with 70 volt rails and 80volt
for the chip?
if yes i could live with that.
it will be dissipating about 60-70 watt per channel?
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PSU tests? my trigger finger is itchy and a lot of build decisions are hinging on the psu I use; in fact its kinda stalled on it. I know you are only able to do testing when you can steal some time after work and probably wanting to get the f**k out of there, but heres me begging for some results =) we may be able to throw together with some of the guys doing the hypex amp GB who are also looking at the DPS600, together the pricing becomes more realistic for my multichannel amp
Hi Qusp,
I also expect the answer to Owen after a few exchanges of new measures concerning in particular the peak at 120Hz (DPS-400). (the extension of the band high, it is extremely clean up to 100 Khz), this is the fft on the output connector with 500mA load. before and after a change to the feedback value.
I am aware that others expect these measures, perhaps with more attention to the dynamic behavior of the DPS-600 (right in this I have always insisted)
However, I can inform you, that after receiving tons of emails, as you say .. maybe they want for a mono-block d class, it was decided that a single price for the two models of DPS-600 (DPS-600 / DA for D class). € 130.00 excluding VAT. This is a way to meet the diy, whereas these SMPS have a high production cost, certainly not as industrial SMPS.
We hope that Owen can turn up soon ..
Regards
Roberto
Attachments
Hi Guys,
We're almost there with the supplies, but I have been holding back on posting anything until we have it just right. It has been a lot of work dialing in these supplies to work perfectly with The Wire amps as we have higher than usual bias current and I'm looking for a very low noise floor.
As a quick update, I can confirm the following:
1. The new modified supplies are extremely quiet, and easily outperform even my best attempts with linear supplies (even with regulated HV)
2. The pricing AP2 is willing to offer our group makes these price competitive (if not lower cost) than a linear supply.
3. The dynamic performance of the supplies far exceeds what a linear supply is capable of.
4. They are a complete solution that offer a plug-n-play option where you know exactly what performance to expect.
5. I did a full set of listening tests last weekend, and I distinctly prefer both the DPS-400 and DPS-600 to the linear supply. My line arrays require huge amounts of power in the bottom end, and this really stresses the amplifiers. Both the DPS-400 and DPS-600 had significantly better bass definition than the linear supply, both in the attack and the decay of bass notes.
There are still a few things for us to iron out overall, and I have one final set of tests to run before I post measurements (awaiting modified supply from AP2). I'm also waiting on a few confirmations about 120V compatible supplies.
These supplies will likely be custom (with the aforementioned modifications), and I'll basically be buying the lot from AP2 and distributing them with the kits when they ship out later this month.
I'll post up pricing once it's final, and I'll start taking orders in the next little bit so everything is in place by the time the mosfets get here!
Cheers,
Owen
We're almost there with the supplies, but I have been holding back on posting anything until we have it just right. It has been a lot of work dialing in these supplies to work perfectly with The Wire amps as we have higher than usual bias current and I'm looking for a very low noise floor.
As a quick update, I can confirm the following:
1. The new modified supplies are extremely quiet, and easily outperform even my best attempts with linear supplies (even with regulated HV)
2. The pricing AP2 is willing to offer our group makes these price competitive (if not lower cost) than a linear supply.
3. The dynamic performance of the supplies far exceeds what a linear supply is capable of.
4. They are a complete solution that offer a plug-n-play option where you know exactly what performance to expect.
5. I did a full set of listening tests last weekend, and I distinctly prefer both the DPS-400 and DPS-600 to the linear supply. My line arrays require huge amounts of power in the bottom end, and this really stresses the amplifiers. Both the DPS-400 and DPS-600 had significantly better bass definition than the linear supply, both in the attack and the decay of bass notes.
There are still a few things for us to iron out overall, and I have one final set of tests to run before I post measurements (awaiting modified supply from AP2). I'm also waiting on a few confirmations about 120V compatible supplies.
These supplies will likely be custom (with the aforementioned modifications), and I'll basically be buying the lot from AP2 and distributing them with the kits when they ship out later this month.
I'll post up pricing once it's final, and I'll start taking orders in the next little bit so everything is in place by the time the mosfets get here!
Cheers,
Owen
ok mate, that about seals it for me, time to start putting aside a bit of coin. i'll likely go for 2 x DPS600 and 2 x DPS400. yes its the dynamic performance that has me interested as i figured this would be where the edge would be (apart from efficiency of course) so you are looking at the interfacing being custom to fit with the amp as well?
does the requirement for 10-15kuF on each rail for higher loads hold for CLASS AB as well as D? at what power is this expected to be installed? I ask because i would expect this to slow any dynamic advantage over linear
opc: many of these audio tests for switching supplies do not pay huge attention to higher bandwidth; treating above 50-100kHZ as out of band, i would like to request at least one test around the carrier and its sidebands, being that the LPUHP and its bigger brother, are DC coupled in my builds and they are wide band as hell i would think its a bit more important, particularly as sample rate if not actual music bandwidth creeps up every year and it would be interesting to see whether anything clashes with dac clock speeds right up in the MHZ range.
anyway thanks guys for the continued efforts to work together to extend the already stellar performance of the amp. i'm not surprised the ncore mob became interested Roberto, these are seriously top notch looking/performing supplies and you should be proud that its caussing a bit of a stir in relation to the 2 top measuring projects on a forum that is a pretty tough crowd and in general a bit biased against switching supplies. the fact that the performance is so good that it becomes difficult to ignore is a credit to you both.
does the requirement for 10-15kuF on each rail for higher loads hold for CLASS AB as well as D? at what power is this expected to be installed? I ask because i would expect this to slow any dynamic advantage over linear
opc: many of these audio tests for switching supplies do not pay huge attention to higher bandwidth; treating above 50-100kHZ as out of band, i would like to request at least one test around the carrier and its sidebands, being that the LPUHP and its bigger brother, are DC coupled in my builds and they are wide band as hell i would think its a bit more important, particularly as sample rate if not actual music bandwidth creeps up every year and it would be interesting to see whether anything clashes with dac clock speeds right up in the MHZ range.
anyway thanks guys for the continued efforts to work together to extend the already stellar performance of the amp. i'm not surprised the ncore mob became interested Roberto, these are seriously top notch looking/performing supplies and you should be proud that its caussing a bit of a stir in relation to the 2 top measuring projects on a forum that is a pretty tough crowd and in general a bit biased against switching supplies. the fact that the performance is so good that it becomes difficult to ignore is a credit to you both.
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Hi all,
thanks for some appreciation.
yes, DPS-400 have remote control. is better than at this point, I put a small list of certain changes, for this model dedicated to the wire Amp
just the remote control has been modified to simplify the wiring. and support led directly as pic.
For voltage option, first version have +/-58V @230Vac as agreemnt with Opc .
But, if there are requests, a version with lower voltage eg. 36V may be available
Regards
Roberto
Attachments
If we get our usual feeding frenzy for anything opc offers on these forums then AP2 could have a similar world wide shortage to the flood-induced world wide shortage of the lateral FETS! Or the significantly depleted stock at digikey for the lme49600 for that matter.
I'm probably interested in a few of these for my Class AB The Wires and a couple extra to replace an existing smps in another amp of mine.
I hope the flood gates haven't opened here for people expressing interest but I certainly think we've already demonstrated to AP2 that there is likely to be a stampede! If these power supplies are as good as preliminary indications suggest (and AP2s assertions all along) then the demand is a great reward for the development that has gone into your products.
I'm probably interested in a few of these for my Class AB The Wires and a couple extra to replace an existing smps in another amp of mine.
I hope the flood gates haven't opened here for people expressing interest but I certainly think we've already demonstrated to AP2 that there is likely to be a stampede! If these power supplies are as good as preliminary indications suggest (and AP2s assertions all along) then the demand is a great reward for the development that has gone into your products.
AP2, thanks for the info. The effort both yourself and opc are expending upon this is awesome and very much appreciated
In the intrest of trying to keep things sane, I'm happy to go with what's been agreed upon between you two... I'll just have to keep the volume turned down, or get new neighbours.
In the intrest of trying to keep things sane, I'm happy to go with what's been agreed upon between you two... I'll just have to keep the volume turned down, or get new neighbours.
Objection!
As long as your linear supplies don't have the "dynamic" performance of the SMPS's, they are sub optimal.
I'd like to see your statement backed up by some measurements, because IMO dynamic behaviour of power supplies has everything to do with inner resistance, and creating a linear supply with at least the same low inner resistance of the SMPS is just a matter of design.
The main difference is that we deal with multiple tens of kHz with SMPS's, and 50 / 60 Hz for the linear supplies.
Designing a low inner resistance linear supply requires a high power transformer; a 500VA toroid for a 300 watt class B amplifier will not get you there.
I roughly calculated a 230 / 50 + 50 power supply transformer for the Wire amp to have some 0.8 ohms of primary DCR, and under 0.1 ohms for each secondary; the transformer core is a 1200VA c-core!
Comparing this linear supply (with no more than some 2 x 10.000 uF of capacitance) with a high quality SMPS might be surprising. By the way: tons of capacitance in supplies driving a class B amp together with an underrated transformer is IMO one of the most common made mistakes.
It is clear that SMPS's are more efficient, just like class D amplifiers are more efficient than their class A/B brothers, but at least until now I have not heard either topology to "sound" better than their linear counterparts.
Nevertheless my compliments to this thread, which is all what DIY is about.
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Hi Pieter, your topic can help me in this "odyssey" of linear transformer and SMPS. This is a topic that I have tried several times to explain but ... the rest you know him.
I omit the numerous interventions in the research, just to get a clean output, now then, compare with the linear transformer seriously. we speak of the dynamics. when referring the output impedance of the transformer, must be calculated that because of the ripple, the output voltage is already dropped. This is sufficient to change the geometry of the burst (audio transients). This is the reason for which you place huge capacity (in serious big amp).
well, now we make a comparison with regulated SMPS .... But, what kind of regulated SMPS? regulated all that exists, down from 10 to 14 volts under burst. primary reason is because of the slow response. for this reason it was created the DPS-600, in fact, to get this special performances (only 2.7 V drop under burst, repetitive 450w), offers a realism that we are not accustomed to hearing. Therefore, if the performance of this special smps are real, you can not compare it as a conventional SMPS. apart, from the total absence of harmonics in the output, only this change performances in a D class amp.
at end.. some simple measure show all.
I do not believe in mysteries, but what can be explained scientifically.
Regards
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