Hi Bill,
I am looking forward to your impressions/assessment. This simple amplifier topology was conceived to elegantly surpass current methods, leaving little or no sonic signature while delivering the highest power efficiency (for Class AB) and PSRR - requiring a smaller supply resource to achieve it.
Waiting for results.
Cheers,
Greg
I am looking forward to your impressions/assessment. This simple amplifier topology was conceived to elegantly surpass current methods, leaving little or no sonic signature while delivering the highest power efficiency (for Class AB) and PSRR - requiring a smaller supply resource to achieve it.
Waiting for results.
Cheers,
Greg
Hi ShinOBIWAN,
Saw your power supplies - those BMM CRC's!!! They'll be right up to the +/-56V max recommended with my GB150D modules. You can even use a pair of 225VA transformers ( 1.5 x amp power as recommended by BMM) with them as they're very insensitive to power supply artefacts, by design.
Looking forward to your impressions.
Cheers,
greg
Saw your power supplies - those BMM CRC's!!! They'll be right up to the +/-56V max recommended with my GB150D modules. You can even use a pair of 225VA transformers ( 1.5 x amp power as recommended by BMM) with them as they're very insensitive to power supply artefacts, by design.
Looking forward to your impressions.
Cheers,
greg
Hi ShinOBIWAN,
Close on the power supply calculations, but, at the risk of being pedantic, this is how the sums add up -
Take a 225VA transformer with a 35-0-35 Vac secondary. That rating means, at the full VA demand (load)this will produce the stated 35-0-35V ac.
Into a bridge this rectifies up to 35 (each side) x 1.414 = 49.49V -1 diode drop (circa 0.7V) being the peak of the sine wave into a capacitative load less a small amount of ripple depending on the size of the storage capacitors.
So we have roughly 48.3V DC UNDER LOAD of 225VA, with say 1Vp-p ripple (a typical design figure).
However, under 100mA (SKA quiescent demand) load, the supplies run higher by the regulation of the transformer, say about +7 to 8% for a 225VA transformer. So idle voltage is likely to be approx 52.3V. If the transformer were smaller say 160VA with poorer regulation, volts would be increased by about 10% , if 300VA, up by about 6%.
I doubt overvoltage of mains supply is consistently significant. They won't be particularly interested in delivering more power than you're paying for.
I used to teach this stuff.
Cheers,
Greg
Close on the power supply calculations, but, at the risk of being pedantic, this is how the sums add up -
Take a 225VA transformer with a 35-0-35 Vac secondary. That rating means, at the full VA demand (load)this will produce the stated 35-0-35V ac.
Into a bridge this rectifies up to 35 (each side) x 1.414 = 49.49V -1 diode drop (circa 0.7V) being the peak of the sine wave into a capacitative load less a small amount of ripple depending on the size of the storage capacitors.
So we have roughly 48.3V DC UNDER LOAD of 225VA, with say 1Vp-p ripple (a typical design figure).
However, under 100mA (SKA quiescent demand) load, the supplies run higher by the regulation of the transformer, say about +7 to 8% for a 225VA transformer. So idle voltage is likely to be approx 52.3V. If the transformer were smaller say 160VA with poorer regulation, volts would be increased by about 10% , if 300VA, up by about 6%.
I doubt overvoltage of mains supply is consistently significant. They won't be particularly interested in delivering more power than you're paying for.
I used to teach this stuff.
Cheers,
Greg
Thanks for the explaination. I did say it was 52-53v but you corrected me with 52.3v
Also, its stange but BMM recommend no higher than 40-0-40 traffo's and I've used them with this when I built some of Rod Elliots ESP P101 amp. This resulted in 58-59v rails yet on the same token BMM recommends 56v max. I'll have to email Jean at BMM for clarification.
Also, its stange but BMM recommend no higher than 40-0-40 traffo's and I've used them with this when I built some of Rod Elliots ESP P101 amp. This resulted in 58-59v rails yet on the same token BMM recommends 56v max. I'll have to email Jean at BMM for clarification.
Hi ShinOBIWAN,
I think you'll find that the mains voltage is subject to a number of determinants -
1) how close you are to source along a long grid - further away further grid losses.
2) Demand. Just like a transformer in equipment, the grid has it's intrinsic impedance, and will be highest under low demand and lower at peak demand. This can be evidenced at evening meal time or on a hot day with air-conditioning /fans being used which pull it down.
3) The power company will try to maintain an average for everyone of around the nominal volts.
In the case of your transformer outputs -
Take the case of a 40-0-40 and assume nominal mains input, full wave bridge, Iq amp load say 100mA, and typical for VA size regulation -
For 160VA will give typ +/-60V
for 225VA will give typ +/- 59V
for 300VA will give typ +/- 58V
for 500VA will give typ +/-57V
- see a pattern ... higher VA less variation from no load to full load as all will give typ +/-55.5V at their full VA load rating.
Your diurnal or seasonal fluctuation of mains voltage simply modulate this, hopefully within their stated +/- (typ) 10% limits.
Cheers,
Greg
I think you'll find that the mains voltage is subject to a number of determinants -
1) how close you are to source along a long grid - further away further grid losses.
2) Demand. Just like a transformer in equipment, the grid has it's intrinsic impedance, and will be highest under low demand and lower at peak demand. This can be evidenced at evening meal time or on a hot day with air-conditioning /fans being used which pull it down.
3) The power company will try to maintain an average for everyone of around the nominal volts.
In the case of your transformer outputs -
Take the case of a 40-0-40 and assume nominal mains input, full wave bridge, Iq amp load say 100mA, and typical for VA size regulation -
For 160VA will give typ +/-60V
for 225VA will give typ +/- 59V
for 300VA will give typ +/- 58V
for 500VA will give typ +/-57V
- see a pattern ... higher VA less variation from no load to full load as all will give typ +/-55.5V at their full VA load rating.
Your diurnal or seasonal fluctuation of mains voltage simply modulate this, hopefully within their stated +/- (typ) 10% limits.
Cheers,
Greg
I think Greg is one of those people who really knows what he's doing. For him its a science not a whim with a paint brush.
I must say inital impressions are one of clarity and neutrality, that is not a wine makers blended Cab Sav like we see so many off.
Its really a case of building it and finding out for yourself.
I will post something over the weekend.
Macka
I must say inital impressions are one of clarity and neutrality, that is not a wine makers blended Cab Sav like we see so many off.
Its really a case of building it and finding out for yourself.
I will post something over the weekend.
Macka
My Mosfet A40s are nearly done, only need to finish the chassis.
The GB/SKA boards should be on route overhere, i settle with 50 in A.
Grosso modo, the components for both will be the same.
Same toroids, electrolytics, RCAs, binding posts, wiring, output devices.
Should make a nice comparison.
The GB/SKA boards should be on route overhere, i settle with 50 in A.
Grosso modo, the components for both will be the same.
Same toroids, electrolytics, RCAs, binding posts, wiring, output devices.
Should make a nice comparison.
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