Here is an new Amp for You :
http://www.a-and-t-labs.com/K6_Sw_Amp/
I found This amp coincidentally few day's ago.
What do you think about it ?
For me it looks verry reliably.
I would use it as an sub Amp for my XLS12 Driver. The advantage of this amp is the include protection and the presentet Layout.
By the way: I would be happy getting from soneone an PCB for Holtons N-Channel.
Regards,
Andi
PS. I made an Activ Controller for the sub with an 24 dB High Pass ( 25 Hz ) and an Variabel 24 dB Lowpass . Additional 2 Ful Parametric Filter for Equalisations.
If somebody is interested in ...
http://www.a-and-t-labs.com/K6_Sw_Amp/
I found This amp coincidentally few day's ago.
What do you think about it ?
For me it looks verry reliably.
I would use it as an sub Amp for my XLS12 Driver. The advantage of this amp is the include protection and the presentet Layout.
By the way: I would be happy getting from soneone an PCB for Holtons N-Channel.
Regards,
Andi
PS. I made an Activ Controller for the sub with an 24 dB High Pass ( 25 Hz ) and an Variabel 24 dB Lowpass . Additional 2 Ful Parametric Filter for Equalisations.
If somebody is interested in ...
Attachments
This amp design was published in Electronics Now in the October and November 1995 issues. It's good to see that they are still selling parts for the amp.
It seems like a good design, but a few things bother me. My thoughts expressed below may not be technically accurate so someone should correct me if I'm wrong.
There is no short circuit protection. Also, with the rails set at +/- 82V I'd be weary of using only 4 pairs of output MOSFETs. You most certainly couldn't drive less than 8 ohms at that level.
There are no source resistors to help match the currents in the output MOSFETs. Without them the transistors would have to be perfectly matched. Even then a difference in temperature between devices would create an imbalance in current sharing.
Is the switching PSU really necessary? I suppose if you want the amp to be really lightweight, it may help. Maybe it helps the transient response, too.
With the rails set at +/- 82V the voltage across the LM317/337 regulators exceeds the 40V maximum differential. Is this safe if the current is kept low?
They must have done something right if they can quote such impressive specs. I'd love to hear from anyone who has actually built this amp. I'd like to know if the considerable expense and complexity is worth it. It's definitely not a first-time project.
It seems like a good design, but a few things bother me. My thoughts expressed below may not be technically accurate so someone should correct me if I'm wrong.
There is no short circuit protection. Also, with the rails set at +/- 82V I'd be weary of using only 4 pairs of output MOSFETs. You most certainly couldn't drive less than 8 ohms at that level.
There are no source resistors to help match the currents in the output MOSFETs. Without them the transistors would have to be perfectly matched. Even then a difference in temperature between devices would create an imbalance in current sharing.
Is the switching PSU really necessary? I suppose if you want the amp to be really lightweight, it may help. Maybe it helps the transient response, too.
With the rails set at +/- 82V the voltage across the LM317/337 regulators exceeds the 40V maximum differential. Is this safe if the current is kept low?
They must have done something right if they can quote such impressive specs. I'd love to hear from anyone who has actually built this amp. I'd like to know if the considerable expense and complexity is worth it. It's definitely not a first-time project.
Some thoughts about the SMPS :
- It looks like deep cost reduction has been applied since it lacks some elements [read further]
- It's overpriced, it should cost half or less money
- It lacks input differential mode filter
- It lacks output cross-regulation since there are two independent output inductors instead of a single coupled inductor with two windings, this is really a bad design practice
- It lacks output pi filter, adding one should reduce output ripple by 20-40dB
- It appears to use voltage-mode control altough it has a current transformer making current-mode control easy to implement with an adittional op-amp and some small components
- It uses mosfets for switching, being 2-4 times more expensive than similar IGBTs with lower conduction losses as a bonus
- It works at 55Khz, relatively slow for MOSFET capabilities, raising it to 110Khz could almost double output power [2Kw instead of 1Kw] without changing the size of magnetic components
- Driving MOSFETs directly from a pulse transformer at 55Khz is a bad idea because high value gate resistors have to be used to avoid resonance between transformer leakage inductance and gate capacitance, slowing down switching, increasing crossover times and switching losses
- Driving this pulse transformer directly from a SG3525IC with only +-500mA peak current capability and without a capacitor in series to compensate DC generated by pulse asimetry and avoid pulse transformer saturation is even worse since it puts reliability into compromise and is a sign of poor design
-The IC is driving an equivalent load of about 20 ohms in series with 24nF, plus the effects of the high reverse transfer capacitance present in these MOSFETs so charging the gates would require more tan 1uS, even 2uS [the IC is working at its absolute maximum ratings]
- The power supply should come inside a metal box [connected to ground] to get full shielding on electric fields and someting like 20dB atenuation on stray magnetic fields [I think this would make it quieter than a 50Hz supply]
- It looks like deep cost reduction has been applied since it lacks some elements [read further]
- It's overpriced, it should cost half or less money
- It lacks input differential mode filter
- It lacks output cross-regulation since there are two independent output inductors instead of a single coupled inductor with two windings, this is really a bad design practice
- It lacks output pi filter, adding one should reduce output ripple by 20-40dB
- It appears to use voltage-mode control altough it has a current transformer making current-mode control easy to implement with an adittional op-amp and some small components
- It uses mosfets for switching, being 2-4 times more expensive than similar IGBTs with lower conduction losses as a bonus
- It works at 55Khz, relatively slow for MOSFET capabilities, raising it to 110Khz could almost double output power [2Kw instead of 1Kw] without changing the size of magnetic components
- Driving MOSFETs directly from a pulse transformer at 55Khz is a bad idea because high value gate resistors have to be used to avoid resonance between transformer leakage inductance and gate capacitance, slowing down switching, increasing crossover times and switching losses
- Driving this pulse transformer directly from a SG3525IC with only +-500mA peak current capability and without a capacitor in series to compensate DC generated by pulse asimetry and avoid pulse transformer saturation is even worse since it puts reliability into compromise and is a sign of poor design
-The IC is driving an equivalent load of about 20 ohms in series with 24nF, plus the effects of the high reverse transfer capacitance present in these MOSFETs so charging the gates would require more tan 1uS, even 2uS [the IC is working at its absolute maximum ratings]
- The power supply should come inside a metal box [connected to ground] to get full shielding on electric fields and someting like 20dB atenuation on stray magnetic fields [I think this would make it quieter than a 50Hz supply]
Protection : How Important
First I was verry impressed by this amp.
But I see the problems.
And yesterday i decided, building an Holton .
My Question now:
(the amp above was my fist choice specally because of the dc and Temp protection )
Holtons amp's have non protection.
How important are a protection, if i use the amp in my subwoofer fixed connected and with an appropriately heat sink ?
By building conscientiously the amp:
How hight is the probability kill my expensive ( for a pur Sudent ) XLS 8 Ohm Driver, without an Protection ?
First I was verry impressed by this amp.
But I see the problems.
And yesterday i decided, building an Holton
. My Question now:
(the amp above was my fist choice specally because of the dc and Temp protection )
Holtons amp's have non protection.
How important are a protection, if i use the amp in my subwoofer fixed connected and with an appropriately heat sink ?
By building conscientiously the amp:
How hight is the probability kill my expensive ( for a pur Sudent ) XLS 8 Ohm Driver, without an Protection ?
Have anoyone an Layout for the Holton's N-Channel ( it is no more avaibel at holton's Homepage )
I have added a projekt seems nearly a coppy of Holtons N-Channel.
How good is this ?
I'm not shure use the Symm. or N-Channel, witch is the better one in this chase ?
Or both are well usable?
already times until here much thank's
Andi
I have added a projekt seems nearly a coppy of Holtons N-Channel.
How good is this ?
I'm not shure use the Symm. or N-Channel, witch is the better one in this chase ?
Or both are well usable?
already times until here much thank's
Andi
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