I did some comparation between LM4562 and LM6172 (the original NewClassD opamp).
Set them up in a standard inverting G=-1 configuration, with 4k99 resistors to compare their THD against each other. Both measurements done with 1 Vrms line level signal.
Here is what i found:
LM6172:
LM4562:
As you can see there are almost no differences, however the LM6172 has (just) lower THD in most of the frequency range.
I did change to other specimens for both opamps, but found the tendencies were exactly the same. So no reason really to opt for the LM4562, based on THD.
Set them up in a standard inverting G=-1 configuration, with 4k99 resistors to compare their THD against each other. Both measurements done with 1 Vrms line level signal.
Here is what i found:
LM6172:
LM4562:
As you can see there are almost no differences, however the LM6172 has (just) lower THD in most of the frequency range.
I did change to other specimens for both opamps, but found the tendencies were exactly the same. So no reason really to opt for the LM4562, based on THD.
wtfaidh..
Try to find You a case here on this site http://www.autocostruire.com/
they have a few nice looking cases at very good prices.
Have searched for long without finding something with better price/looks performance.
Try to find You a case here on this site http://www.autocostruire.com/
they have a few nice looking cases at very good prices.
Have searched for long without finding something with better price/looks performance.
Sharkythefrog: I've ordered mine from Ulveco/Noratel in Norway. They make high quality trafos, stock a wide selection of models, and can make custom toroids without too much of a price premium. I payed NOK1300 each for two 1300VA 42-42-15V custom wound on audio grade core. Nice, heavy suckers 
They've made an 800VA unit on ELFA, but it's about 50% more expensive than getting the same audio spec trafo from Ulveco. Don't know how they are when it comes to international orders, though.
But there are threads on this elsewhere on the forum.
They've made an 800VA unit on ELFA, but it's about 50% more expensive than getting the same audio spec trafo from Ulveco. Don't know how they are when it comes to international orders, though.
But there are threads on this elsewhere on the forum.
I still have a wonder about this with the big trafos You guys are using. I´m not an ee but what I understand is that a classD amp is far more efficient that an class a/ab amp, especially when running on high levels (where the trafo power should be needed most).
1) Why use huge trafos lke 1300 VA?
2) And to which level of trafo is amp performance enhancing steeply and where do it "flattens out"
Maybe some of You have tried different trafos on this NCD and have some info to share - Maybe You have Lars (the cookbook does not tell).
Hope this is not off topic - as it´s just about the NCD trafo level.
1) Why use huge trafos lke 1300 VA?
2) And to which level of trafo is amp performance enhancing steeply and where do it "flattens out"
Maybe some of You have tried different trafos on this NCD and have some info to share - Maybe You have Lars (the cookbook does not tell).
Hope this is not off topic - as it´s just about the NCD trafo level.
Yes I did see Your earlier post about the fuse thing. Strange thing. As far as I could read the R-trafos are the square things and the O-trafos are the round toroids normally used in normal-to-better hifi equipment, or am I wrong?!?
I´m only looking for the round toroids.
Have You compared with and without extra stiffener caps to the NCD PSU-board to get more (base) power?
Maybe as a substitute to larger trafo . . .
What´s the common meaning, does it work this way and/or does it affect even the mid and high?
I´m only looking for the round toroids.
Have You compared with and without extra stiffener caps to the NCD PSU-board to get more (base) power?
Maybe as a substitute to larger trafo . . .
What´s the common meaning, does it work this way and/or does it affect even the mid and high?
Sharkythefrog said:
The ones I've used are rated for 400VA, which worked quite well when we tried to driver a 4ohm PMC speaker. The bass was very well controlled, and better than what the PMC owner was originally using (which sounded mushy).
I have not tried extra caps, and have not studied the technical details associated with transformer performance, I'm actually interested in trying SMPS. I'm thinking about plugging in the 48V ones I have just for a small test when I have the time.
Elektrokit sell a 2x42V 500VA transformer at the price of 746 Skr including our high (25%) sales tax. Use two of them ,eighter one for the positive and one for the negative rail, or one per channel.
If you are not going to use speakers which are extremely difficult for the amps, I guess this will be quite good.
Transformers are heavy items, thus shipping cost should be considered. Higher rates from abroad, naturally!
But here is a link to the Dutch company BMM,as well:
transformers
Here´s also a quote from ]Alner Hamblins site.
"The SA400 is the result of everything learnt in the subsequent years and uses a new board we designed to take the latest Tripath 105A chips and to incorporate extra facilities to lift the earth (to prevent earth loops) and be able to vary the amplifier gain to match other system sensitivities. The original massive power supply has worked so well in providing effortless sound reproduction that it has been retained without change. It uses twin transformers, which supply separate full wave positive and negative supply lines. The zero volt reference is then made at DC, not at AC via the usual centre tap on the transformer, together with a bi-phase rectifier. This approach improves the stability of the zero volt line by ensuring that each supply line is separate from the other during high load current demands. Other advantages include a reduction in the power supply pumping effect (common to all switched output stages, which use an inductor for digital to analogue reconstruction), and also helps to remove DC from the transformer, which can be responsible for increased noise (hum) from the transformer, especially at switch on."
In summery:
If you look under products and the SA 400 amp, there is a comment about preferences for using two transformers , and one for each rail. Using a centertapped transformer and just one bridge rectifier, should lead to an unstable or fluctuating 0-Volt reference level.
If you are not going to use speakers which are extremely difficult for the amps, I guess this will be quite good.
Transformers are heavy items, thus shipping cost should be considered. Higher rates from abroad, naturally!
But here is a link to the Dutch company BMM,as well:
transformers
Here´s also a quote from ]Alner Hamblins site.
"The SA400 is the result of everything learnt in the subsequent years and uses a new board we designed to take the latest Tripath 105A chips and to incorporate extra facilities to lift the earth (to prevent earth loops) and be able to vary the amplifier gain to match other system sensitivities. The original massive power supply has worked so well in providing effortless sound reproduction that it has been retained without change. It uses twin transformers, which supply separate full wave positive and negative supply lines. The zero volt reference is then made at DC, not at AC via the usual centre tap on the transformer, together with a bi-phase rectifier. This approach improves the stability of the zero volt line by ensuring that each supply line is separate from the other during high load current demands. Other advantages include a reduction in the power supply pumping effect (common to all switched output stages, which use an inductor for digital to analogue reconstruction), and also helps to remove DC from the transformer, which can be responsible for increased noise (hum) from the transformer, especially at switch on."
In summery:
If you look under products and the SA 400 amp, there is a comment about preferences for using two transformers , and one for each rail. Using a centertapped transformer and just one bridge rectifier, should lead to an unstable or fluctuating 0-Volt reference level.
The golden mean said:
Hi,
BMM is a dutch reseller for Amplimo transformers (among other things). You can also buy them strait from the factory... at http://www.amplimo.nl/
Succes, Eric.
Ok Tgm!
After a dialogue with Lars C I´ll probably set up a dual mono amp wtih two of his 4-wire 15000/63 PSBs.
From what I could read (and understand as a newbi and not native english speaker) in the quote in Your post the recommendation the recommendation is two trafos for a stereo setup. That would be four trafos for a dual mono setup, and I promise You i will not buy four trafos for my first D-class amp (except from two SI-Tamps which are under mod for two of my oldest kids - out of three)......
The NCD setup will hopfully take over from an old Accuphase E202 that this far has proven worthy serving my means better than a number of amps brought home from different stores over the years. The speakers to be loaded since 3 years is a 3-way two year multi company (calculation, components, measurements, cases, electronic buildings etc) project based on Thiel components. Very crisp, open and clear (love electrostatic speakers) with a deeeep And fast base.
We´lll see how NCD gonna like that - I have no idea of the load from those speakers, but 6 kg of the best components in the filters might pay out
After a dialogue with Lars C I´ll probably set up a dual mono amp wtih two of his 4-wire 15000/63 PSBs.
From what I could read (and understand as a newbi and not native english speaker) in the quote in Your post the recommendation the recommendation is two trafos for a stereo setup. That would be four trafos for a dual mono setup, and I promise You i will not buy four trafos for my first D-class amp (except from two SI-Tamps which are under mod for two of my oldest kids - out of three)
......The NCD setup will hopfully take over from an old Accuphase E202 that this far has proven worthy serving my means better than a number of amps brought home from different stores over the years. The speakers to be loaded since 3 years is a 3-way two year multi company (calculation, components, measurements, cases, electronic buildings etc) project based on Thiel components. Very crisp, open and clear (love electrostatic speakers) with a deeeep And fast base.
We´lll see how NCD gonna like that - I have no idea of the load from those speakers, but 6 kg of the best components in the filters might pay out
Interesting site Amplimo wtfaidh...
A trafo company probably with an owner that are interested in hifi and has diversified his company with some nice hifi stuff...
I guess the shipping from NL and the € would make it a better deal to use Elktrokit i sweden the two trafos I would need to get. Thanks anyway.
Would be nice to hear some other comments on trafo size to..
A trafo company probably with an owner that are interested in hifi and has diversified his company with some nice hifi stuff...
I guess the shipping from NL and the € would make it a better deal to use Elktrokit i sweden the two trafos I would need to get. Thanks anyway.
Would be nice to hear some other comments on trafo size to..
I just figure once more why I over and over again are carrying home amps to substitute the Accu... it somewaht breaks up at high volume on "complex" music - at this moment Staind and earlier Donald Fagen (with synthetic basses and drums affecting the mid and high)..
Hope I wll not find that happen with the NCD with two 500VA trafos
Looking forward to hear some more new sound experiences from some of the ones that are building at the moment.
For me this will be a SI-Tampmoddingweekend to get my kids some more proper sound (carried out an old Pana and a Sentec last week). Then it´s time for NCD.....
Hope I wll not find that happen with the NCD with two 500VA trafos
Looking forward to hear some more new sound experiences from some of the ones that are building at the moment.
For me this will be a SI-Tampmoddingweekend to get my kids some more proper sound (carried out an old Pana and a Sentec last week). Then it´s time for NCD.....
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