Re: SKA, Greg Balls "wonder box" 300D / SMPS
Hi Stoeffle,
WRT CM noise, I am assuming you are referring to SMPS OP and not
mains IP noise.
Where does the SMPS ref to chassis/mains gnd or is the OP
floating?
At hwat frequency are they run at?
Cheers
Terry
stoeffle said:
Hi Stoeffle,
WRT CM noise, I am assuming you are referring to SMPS OP and not
mains IP noise.
Where does the SMPS ref to chassis/mains gnd or is the OP
floating?
At hwat frequency are they run at?
Cheers
Terry
smps
hi stoeffle, what meanwell smps model no. did you use? looking forward to the tweaks you mentioned in the constructor's thread..thanks!
hi stoeffle, what meanwell smps model no. did you use? looking forward to the tweaks you mentioned in the constructor's thread..thanks!
Thread #479
Hi pinkmouse,
good point! 😀
I just posted it here on this SKA thread as it touches this amp directly.
so long
stoeffle.++++
pinkmouse said:
Hi pinkmouse,
good point! 😀
I just posted it here on this SKA thread as it touches this amp directly.
so long
stoeffle.++++
Re: Re: SKA, Greg Balls "wonder box" 300D / SMPS
Hi mfc,
noise on power rails has several sources/origins:
1. external ones, coming from the AC power network have a wide variety of forms:
1.1 broadband noise, usually at a low power level, reaching up to several MHz;
1.2 50/60Hz multiples (typical "comb structure") generated by phase control devices (dimmers, etc);
1.3 commutation noise from series operated universal motors (AC/DC type in vacuum cleaners, hand drills and alike);
1.4 switching noise from light switches and alike, capable of providing very high dV/dt values (may blow your tweeters easily);
2. internal noise from the power supply itself,
2.1 be it from a bridge rectifier conducting only for a fraction of the cycle and thus generating abusive current spikes. The transition from conduction to cut-off is usually compleneted by a damped oscillation, capable of generating EMI spectra way up 60..70MHz. (add some 1nF foil caps i // with the diodes, to kill this oscillation)
Then,
2.2 having a SMPS we get its own noise contribution, of course. But, as the modern SMPS rather do their swiching at high frequencies (mine works at fixed 100kHz), this part can be filtered out quite easily.
So, in a nutshell you have to protect your circuit against EMI threats from outside as well as your own, home made one.
Using a proper dimensioned EMI filter at the firewall of your equipment is good practice and highly reccomendable, as you protect yourself against external intrusion and, at the same time, reduce your EMI contribution into the power line network.
Filtering the SMPS output leaves a neat, clean and regulated DC power source. 😀
One thing to remember is that the usual home AC power line wiring is a quite high lossy one, regarding high frequency responses. Large switching amplitudes are reduced quite well after some metres of cabling. Nevertheless, a VDR surge limiter is helpful to supress kV spikes which may easily destroy sensitive electronics.
I hope you got my idea...
so long,
stoeffle.++++
mfc said:
Hi mfc,
noise on power rails has several sources/origins:
1. external ones, coming from the AC power network have a wide variety of forms:
1.1 broadband noise, usually at a low power level, reaching up to several MHz;
1.2 50/60Hz multiples (typical "comb structure") generated by phase control devices (dimmers, etc);
1.3 commutation noise from series operated universal motors (AC/DC type in vacuum cleaners, hand drills and alike);
1.4 switching noise from light switches and alike, capable of providing very high dV/dt values (may blow your tweeters easily);
2. internal noise from the power supply itself,
2.1 be it from a bridge rectifier conducting only for a fraction of the cycle and thus generating abusive current spikes. The transition from conduction to cut-off is usually compleneted by a damped oscillation, capable of generating EMI spectra way up 60..70MHz. (add some 1nF foil caps i // with the diodes, to kill this oscillation)
Then,
2.2 having a SMPS we get its own noise contribution, of course. But, as the modern SMPS rather do their swiching at high frequencies (mine works at fixed 100kHz), this part can be filtered out quite easily.
So, in a nutshell you have to protect your circuit against EMI threats from outside as well as your own, home made one.
Using a proper dimensioned EMI filter at the firewall of your equipment is good practice and highly reccomendable, as you protect yourself against external intrusion and, at the same time, reduce your EMI contribution into the power line network.
Filtering the SMPS output leaves a neat, clean and regulated DC power source. 😀
One thing to remember is that the usual home AC power line wiring is a quite high lossy one, regarding high frequency responses. Large switching amplitudes are reduced quite well after some metres of cabling. Nevertheless, a VDR surge limiter is helpful to supress kV spikes which may easily destroy sensitive electronics.
I hope you got my idea...
so long,
stoeffle.++++
Re: Re: SKA, Greg Balls "wonder box" 300D / SMPS
Hi Terry Demol,
in fact, we have both! Due to induction effects alog the long power lines, some of the DM noise, converts to CM noise. This is the reason for the balanced current toroidal inductors in those ready available mains filters.
The CM component of the SMPS is a quite large one which, if not dealt with properly at the root, may cause severe headache(s).
The chassis of the SMPS case is at PE potential. The case is used as a heatsink for the internal switching devices and diodes, thus by capacitive coupling, induce a CM component at the "floating" output terminals. "Floating" is at DC, but at AC there is a measurable link of several nF to chassis ground! And this loop has to be closed at the shortest distance aoutside!
Another point to keep in mind is to use twisted pair wiring, wherever possible. This reduces stray inductive EMI fields to a minimum. Keep in mind that the current flowing out of the source has to return to it and opposing magnetic fields cancel themselves to the gratest extent, keeping the stray fields only at very close range of the twisted pair.
The MeanWell SMPS I used, is a 100kHz switcher, a 320-48 unit in a case 321W, with built-in PF correction, a thing a toroidal/rectifier/capacitor power supply never will be able to supply. Huge current spikes at the apex of the sinusoidal AC mains voltage are the result, generating vast amounts of 100/120Hz and multiples, harmonics.
so long...
stoeffle.++++
Terry Demol said:
Hi Terry Demol,
in fact, we have both! Due to induction effects alog the long power lines, some of the DM noise, converts to CM noise. This is the reason for the balanced current toroidal inductors in those ready available mains filters.
The CM component of the SMPS is a quite large one which, if not dealt with properly at the root, may cause severe headache(s).
The chassis of the SMPS case is at PE potential. The case is used as a heatsink for the internal switching devices and diodes, thus by capacitive coupling, induce a CM component at the "floating" output terminals. "Floating" is at DC, but at AC there is a measurable link of several nF to chassis ground! And this loop has to be closed at the shortest distance aoutside!
Another point to keep in mind is to use twisted pair wiring, wherever possible. This reduces stray inductive EMI fields to a minimum. Keep in mind that the current flowing out of the source has to return to it and opposing magnetic fields cancel themselves to the gratest extent, keeping the stray fields only at very close range of the twisted pair.
The MeanWell SMPS I used, is a 100kHz switcher, a 320-48 unit in a case 321W, with built-in PF correction, a thing a toroidal/rectifier/capacitor power supply never will be able to supply. Huge current spikes at the apex of the sinusoidal AC mains voltage are the result, generating vast amounts of 100/120Hz and multiples, harmonics.
so long...
stoeffle.++++
Re: smps
Hi,
it is the MeanWell SP 320-48, case 321W, capable of supplying nominal 48VDC @ 6.7A. Output voltage is adjustable from 41 to 56VDC. Switching freq is fixed @ 100kHz, stated ripple is 240mVpp, which is a value I could verify. Further details on the schematic attached.
so long...
stoeffle.++++
japjag said:
Hi,
it is the MeanWell SP 320-48, case 321W, capable of supplying nominal 48VDC @ 6.7A. Output voltage is adjustable from 41 to 56VDC. Switching freq is fixed @ 100kHz, stated ripple is 240mVpp, which is a value I could verify. Further details on the schematic attached.
so long...
stoeffle.++++
Attachments
I finished my GB150D yesterday. This is my first DIY electronics project, so naturally I have some problems.
Here are my listening impressions: Very impressing. Very dynamic. It has the same dynamics all the way down. From 1K and up it is different from my old amp which is a little tube-like. I won't say anything about preference there yet, but from 1K and down it is incredibly much better. Same level of details, same dynamics and steel control. E.g. the cello made my couch vibrate significantly more than with my old amp. My chest too. The amp seems equally powerful and dynamic throughout the whole spectrum. Plays really effortless. I'm eager to play more in the days to come...
Music played on a Pioneer PD-S06, passive pre-amp and on DIY 4-way JBL monitors.
This is an amp I can recommend.
Here are my listening impressions: Very impressing. Very dynamic. It has the same dynamics all the way down. From 1K and up it is different from my old amp which is a little tube-like. I won't say anything about preference there yet, but from 1K and down it is incredibly much better. Same level of details, same dynamics and steel control. E.g. the cello made my couch vibrate significantly more than with my old amp. My chest too. The amp seems equally powerful and dynamic throughout the whole spectrum. Plays really effortless. I'm eager to play more in the days to come...
Music played on a Pioneer PD-S06, passive pre-amp and on DIY 4-way JBL monitors.
This is an amp I can recommend.
Attachments
Hi All
Just wondering if anybody had any listening impressions, to share, of their umodded or modded GB150D or GB300D (SKA) amps
Just wondering if anybody had any listening impressions, to share, of their umodded or modded GB150D or GB300D (SKA) amps
Hello KLe,
I've just started building my SKA kit. I'm building it dual mono in a single chassis.
How's yours sounding - did you compare it with the Krell?
I've just started building my SKA kit. I'm building it dual mono in a single chassis.
How's yours sounding - did you compare it with the Krell?
Hi HiFiddleHiFiddle said:
Excellent, and good to hear. How much longer before you're ready to turn it on. 😀
Actually, two friends of mine have compared the GB300D to a Krell (I think that it was the 50watt classA model), and the GB300D was definitely better. How about that
I listened to it compared to even a Halcro, and, the Halcro wasn't superior. So, what can I say, how about that
😱 ...Halcro wasn't superior...
Yes - it have " too low " distortion, what is for many people unacceptable, 'cos they like " musical sound ".... 😀
Yes - it have " too low " distortion, what is for many people unacceptable, 'cos they like " musical sound ".... 😀
Low measured or perceived distortion?I was not impressed by the Halcro amp I listened to some years ago. Needless to say, it was in the context of a system, and the "problem" could have been elsewere.😉 More blind listening tests are IMHO needed, why not between a group of amps with relatively simple circuits, and more complex ones.
To me, it seems to be very little correspondence in listening impressions and measured performence, once the amp has "sufficient" low IM or THD . The amps ability to cope with the
transient nature of music, seems to play a key role.
How does a Halcro amp of the original design( non-class D) compare to a SKA, when it comes to listening impressions of different kinds of music?Perhpes different contents of sharp transients in the music, will favour the one or other design?
There may be a benifit of cleverly designed , but relatively simple designs, when asked for reproduction of real music. This is a complex matter, as NFB is consider an intrinsic evil by designers as Charles Hansen.
Make a design and compensate for real or imaginary possible flaws, and you may end up with something that measures very well , under steady-state conditions, but is inferior in a listening test.
A clever designer may very well have the knowledge of which simpifications that are allowed and which should be avoided.
I consider buying a SKA GB 300D kit, and in this case I will report my impressions. Meanwhile , sorry for being theoretical.
The positive reviews of the SKA amps, present here and there in this tread, can it be analysed or related to any trait of their topology? So here whe have a relatively simple design, reported to sound very good,and instead of bashing it on theoretical grounds, as a few members have done, is there something in the design , that is the key to the good sound. Simplicity can´t be the whole answer?
To me, it seems to be very little correspondence in listening impressions and measured performence, once the amp has "sufficient" low IM or THD . The amps ability to cope with the
transient nature of music, seems to play a key role.
How does a Halcro amp of the original design( non-class D) compare to a SKA, when it comes to listening impressions of different kinds of music?Perhpes different contents of sharp transients in the music, will favour the one or other design?
There may be a benifit of cleverly designed , but relatively simple designs, when asked for reproduction of real music. This is a complex matter, as NFB is consider an intrinsic evil by designers as Charles Hansen.
Make a design and compensate for real or imaginary possible flaws, and you may end up with something that measures very well , under steady-state conditions, but is inferior in a listening test.
A clever designer may very well have the knowledge of which simpifications that are allowed and which should be avoided.
I consider buying a SKA GB 300D kit, and in this case I will report my impressions. Meanwhile , sorry for being theoretical.
The positive reviews of the SKA amps, present here and there in this tread, can it be analysed or related to any trait of their topology? So here whe have a relatively simple design, reported to sound very good,and instead of bashing it on theoretical grounds, as a few members have done, is there something in the design , that is the key to the good sound. Simplicity can´t be the whole answer?
Golden mean's comments are interesting in that he raises the issue of dynamic versus steady state sonic performance.
From experience, some amps are great at reproducing leading edge transients, others have a lovely long decay and still others are best at providing the body, substance and timbre of each note.
These are attributes which can be heard but don't correlate at all to the static measurements commonly used.
Cheers,
From experience, some amps are great at reproducing leading edge transients, others have a lovely long decay and still others are best at providing the body, substance and timbre of each note.
These are attributes which can be heard but don't correlate at all to the static measurements commonly used.
Cheers,
hifryer said:
But is there one that does all three ?
That, is the question
Why not...it should be possible
Hi,
or are they mutally exclusive.
How does one design for each of these characteristics?
Once we know how to do each then we can look at combining the characteristics if at all possible.
Would this result in the perfect sounding amp that performs badly in the tests (because the wrong tests are being used)?
or are they mutally exclusive.
How does one design for each of these characteristics?
Once we know how to do each then we can look at combining the characteristics if at all possible.
Would this result in the perfect sounding amp that performs badly in the tests (because the wrong tests are being used)?
this is what makes audio an art and not a science.
the only apparent way at present is hard earned knowledge through experimentation - "voicing" the amplifier.
all the choices made - topology, component types, operating points, power supply regulation, filtering and decoupling. Several orders of magnitude beyond PSPICE!!! and NOT apparent on measurements.
there seem to be few general "rules" as each situation is different.
this approach is open to the criticism of just painting with a palette of colourations BUT many amps appreciated for their outstanding musicallity have been designed this way and are unreproduceable just from a schematic.
perhaps the most responsive to these techniques are very simple, non feedback, tube pre-amps with huge attention paid to all power supplies.
there is no cookbook! however, each commercial designer may have his own closely held secrets
Cheers
the only apparent way at present is hard earned knowledge through experimentation - "voicing" the amplifier.
all the choices made - topology, component types, operating points, power supply regulation, filtering and decoupling. Several orders of magnitude beyond PSPICE!!! and NOT apparent on measurements.
there seem to be few general "rules" as each situation is different.
this approach is open to the criticism of just painting with a palette of colourations BUT many amps appreciated for their outstanding musicallity have been designed this way and are unreproduceable just from a schematic.
perhaps the most responsive to these techniques are very simple, non feedback, tube pre-amps with huge attention paid to all power supplies.
there is no cookbook! however, each commercial designer may have his own closely held secrets
Cheers
It seems the SKA builders are a shy bunch; its been quiet around here lately.
I've finally got round to putting my gb150 together, the boards are very simple to stuff, but as usual the box is a PITA. I used a 300va trafo, single bridge and 37v rails, standard ac coupled config.
Anyway, to the important stuff.
After 25 hours burn in I have to say I'm well impressed. This amp does a great job of just getting out of the way. I've played sampler discs all the way through simply because everything sounds so remarkably natural and tracks I've previously found uninteresting or average are now anything but. This amp is weighty, dynamic, transparent and throws a massive 3D soundstage normally only found with megabuck kit. Lower registers are unusally detailed, bass textures never noticed before appear from familiar discs- and this is without any 'etching' or emphasis of highs.
A friend with jadis and krell amps said he wanted an ska after only 10 minutes.
I was able to try the SKA in a system with densen CD, an ad815 pre and the JMLab alto be's. To say the sound was mindblowing would be an understatement😀
Track after track was accompanied by the thud of jaws hitting ground and incredulous giggling. $200 amps shouldn't be able to do this. The air and soundstage was possibly the best I've ever heard, the room disappeared and tangible, palpable images remained in a walkaround acoustic. You could sit outside of the speakers and still hear (see) a 3D image. Large scale orchestral works were shown in a realistic perspective.
Thoughts of bass slam and treble sparkle seem utterly irrelevent when it appears you can reach out and pat Antonio Forcione on the shoulder.
I've heard a few $100k systems lately, and I'd take this set up over most of them.
Congrats to Greg for producing a special product. You might consider this review a bit OTT, but I've focused on what the ska can do rather than what it can't because I've not had chance to do exhaustive comparisons. I'll save any negatives for another day, when the ska's have settled and I've done some proper comparisons. I'll wager now any criticism will be minor. This amp is a steal.
I've finally got round to putting my gb150 together, the boards are very simple to stuff, but as usual the box is a PITA. I used a 300va trafo, single bridge and 37v rails, standard ac coupled config.
Anyway, to the important stuff.
After 25 hours burn in I have to say I'm well impressed. This amp does a great job of just getting out of the way. I've played sampler discs all the way through simply because everything sounds so remarkably natural and tracks I've previously found uninteresting or average are now anything but. This amp is weighty, dynamic, transparent and throws a massive 3D soundstage normally only found with megabuck kit. Lower registers are unusally detailed, bass textures never noticed before appear from familiar discs- and this is without any 'etching' or emphasis of highs.
A friend with jadis and krell amps said he wanted an ska after only 10 minutes.
I was able to try the SKA in a system with densen CD, an ad815 pre and the JMLab alto be's. To say the sound was mindblowing would be an understatement😀
Track after track was accompanied by the thud of jaws hitting ground and incredulous giggling. $200 amps shouldn't be able to do this. The air and soundstage was possibly the best I've ever heard, the room disappeared and tangible, palpable images remained in a walkaround acoustic. You could sit outside of the speakers and still hear (see) a 3D image. Large scale orchestral works were shown in a realistic perspective.
Thoughts of bass slam and treble sparkle seem utterly irrelevent when it appears you can reach out and pat Antonio Forcione on the shoulder.
I've heard a few $100k systems lately, and I'd take this set up over most of them.
Congrats to Greg for producing a special product. You might consider this review a bit OTT, but I've focused on what the ska can do rather than what it can't because I've not had chance to do exhaustive comparisons. I'll save any negatives for another day, when the ska's have settled and I've done some proper comparisons. I'll wager now any criticism will be minor. This amp is a steal.
Hi floatfloat said:
excellent review 😀 At last my views are comletely vindicated and I don't have too explain my myself, anymore.
As I said in one of my previous posts ... the GB300D was definitely better than the Krell it was compared too. I thought the Krell was the 50watt classA model, but, it was the E400 model.
When compared to a Halco, I left feeling happy that I was using Greg's GB300D. 😱
Thanks float, very much appreciated
I look forward to your future posts
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