Hi,
Actually, to be honest, the rails can be higher than 35V...
Tell that Jeff Rowland and National Semiconductor, I am not the one advocating such montrosities, I am merely pointing out they can be build (I leave the building to others).
Ciao T
Actually, to be honest, the rails can be higher than 35V...
Tell that Jeff Rowland and National Semiconductor, I am not the one advocating such montrosities, I am merely pointing out they can be build (I leave the building to others).
Ciao T
As I already mentioned, I used multiple TDA7294s. They're definitely chipamps, not switchers.
What makes that so, Andrew? Do at least give some reasoning rather than a mere pronouncement.
Hi,
all chipamps that I am familiar with have a current limitation that severely limits their ability to drive reactive loads and low impedance speakers.
Configuring them into bridged mode to drive speakers makes this current delivery problem even worse.
Paralleling demands balancing resistors and good circuit design & implementation.
The more paralleling that is attempted, the higher the proportion of builders that run into problems getting their chipamps to run properly.
There is much anecdotal evidence that paralleling reduces the sound quality delivered to the speakers.
The techniques to enable good balancing seem to absorb power and demand great design and implementation skills that are beyond the vast majority of builders. Even when a good design is proposed, competent builders can have problems.
Let's take your 370W into 8r0 example. The combined pins and components of an 8chipamp bridged and paralleled assembly probably has more complexity than a fully discrete amp of that capability. Results are not guaranteed from Forum experience.
Accept that chipamps suit higher impedance loads and low power. Any thing going the BPA route is simply silly, it's far better to go discrete or use Nationals hybrid of driver stage chip and discrete output stage.
all chipamps that I am familiar with have a current limitation that severely limits their ability to drive reactive loads and low impedance speakers.
Configuring them into bridged mode to drive speakers makes this current delivery problem even worse.
Paralleling demands balancing resistors and good circuit design & implementation.
The more paralleling that is attempted, the higher the proportion of builders that run into problems getting their chipamps to run properly.
There is much anecdotal evidence that paralleling reduces the sound quality delivered to the speakers.
The techniques to enable good balancing seem to absorb power and demand great design and implementation skills that are beyond the vast majority of builders. Even when a good design is proposed, competent builders can have problems.
Let's take your 370W into 8r0 example. The combined pins and components of an 8chipamp bridged and paralleled assembly probably has more complexity than a fully discrete amp of that capability. Results are not guaranteed from Forum experience.
Accept that chipamps suit higher impedance loads and low power. Any thing going the BPA route is simply silly, it's far better to go discrete or use Nationals hybrid of driver stage chip and discrete output stage.
Hi,
Actually, excluding the balancing resistor the same applies to single chips.
I find this depends heavily on application, based on actually doing it. Biggest arrays tried where 8pcs...
Ordering tight tolerance resistors actually nil skill whatsoever.
Possibly, possibly not. Few discrete designs can match the best Amp-Chips. Once you have addressed all the issues the chip amp designers actually took very good care of the discrete amp also gets very complex.
But where CHipamp's can really shine is using single pairs per driver in multi-amplified systems. For example (as suggested) something like the Behringer DCX2496 Digital X-Over modified for direct output from the DAC Chip, straight via an attenuator into a balanced pair (aka bridge) of chipamps.
That way many of the limitations are overcome and several benfits are realised.
Actually, compared to the single ended tube Amp's I personally favour Chipamps are positively powerhouses...
Everything is relative.
Ciao T
Actually, excluding the balancing resistor the same applies to single chips.
I find this depends heavily on application, based on actually doing it. Biggest arrays tried where 8pcs...
Ordering tight tolerance resistors actually nil skill whatsoever.
Possibly, possibly not. Few discrete designs can match the best Amp-Chips. Once you have addressed all the issues the chip amp designers actually took very good care of the discrete amp also gets very complex.
But where CHipamp's can really shine is using single pairs per driver in multi-amplified systems. For example (as suggested) something like the Behringer DCX2496 Digital X-Over modified for direct output from the DAC Chip, straight via an attenuator into a balanced pair (aka bridge) of chipamps.
That way many of the limitations are overcome and several benfits are realised.
Actually, compared to the single ended tube Amp's I personally favour Chipamps are positively powerhouses...
Everything is relative.
Ciao T
Dear Andrew,
I have a 6pcs. BPA300 with servo's and even with 1% gain resistors running on an 8ohm subwoofer running at 37VDC. without any problems. Yes heat, but I attached them to a very big heatsink. The amplifier is super reliable and sound like a beast on this subwoofer. This design is used in a studio monitor in environments where abuses and hardcore use is more rule then exception. Never got any any failure.
Must be said I like them on lower voltages as well for extra safety, but it works, as long you can cool!
It all can be done, with a healthy mind and good design considerations, and is certainly no rocket-science. On this particularly application the LME3886 design is actually chosen over a plan B discrete design for the same application, and turn out to be far more reliable then many discrete designs can offer.
I must say we had the luck that we knew the driver it is designed for, and therefore we could calculate the exact Zobel filter fitting this particularly driver.
The level of "grip" and bass transparency this BPA300 design can have on the subwoofer is simply amazing.
With kind regards,
Bas
I have a 6pcs. BPA300 with servo's and even with 1% gain resistors running on an 8ohm subwoofer running at 37VDC. without any problems. Yes heat, but I attached them to a very big heatsink. The amplifier is super reliable and sound like a beast on this subwoofer. This design is used in a studio monitor in environments where abuses and hardcore use is more rule then exception. Never got any any failure.
Must be said I like them on lower voltages as well for extra safety, but it works, as long you can cool!
It all can be done, with a healthy mind and good design considerations, and is certainly no rocket-science. On this particularly application the LME3886 design is actually chosen over a plan B discrete design for the same application, and turn out to be far more reliable then many discrete designs can offer.
I must say we had the luck that we knew the driver it is designed for, and therefore we could calculate the exact Zobel filter fitting this particularly driver.
The level of "grip" and bass transparency this BPA300 design can have on the subwoofer is simply amazing.
With kind regards,
Bas
Then this comes a bit close...
This is what I am listening to right now For the record this is a bridge monoblock, excluding the inputstage.With kind regards,
Bas
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Interesting. How do you do that, given Thiele-Small parameters for the driver and parameters for the speaker box?
I'm in the same situation, trying to figure out an optimal chipamp for a specific speaker. The speaker is a Beyma 12SW1300Nd in a sealed 30 litre box, for F3 = 118 Hz and Qts = 0,5, with a 58 ohm impedance peak at 90 Hz and just 6 ohms at 20 Hz. It will be crossed over around 130 Hz, so there are some wild phase angles and impedance variations in the passband, and it will get +6 dB digital eq at 20 Hz to flatten the response. Not a trivial load.
I was thinking two LM4780 with one paralleled chip on either side of the loudspeaker (i.e., BPA200) and a suitable Zobel on each chip to keep it stable. Would appreciate any advice!
Do you think that a chipamp could be quiet enough to feed a high or even mid efficiency speaker (I mean in the 91-93db/2,83v range) ? I've made a LM1875 stereo amp from the chipamp kit, it works all very fine, except that it's not really quiet : I can hear a sshhhhhhh in my audax TWO34XO, which are quite sensitive... Nothing really damaging for music when I'm sitting at a normal distance and listen at normal level, but at low level on a high efficiency speaker ?
Maybe those LM3886 or 4780 are dead quiet, any input ?
Maybe those LM3886 or 4780 are dead quiet, any input ?
Its true not only for chipamps, discrete amplifiers too. Doug Self's power amp design book makes plain that the primary cause of distortion in a well-designed discrete amplifier is the output stage. Lower impedance loads make the problem worse as you say.
All amplifiers demand good circuit design and implementation if the desired result is a reliable working device. Its not true that balancing resistors are demanded in all applications. TDA7293s parallel nicely without balancing resistors. My 8 * LM1876 prototype design is working nicely without paralleling resistors too. When I come to publish it, maybe you'll see how.
This goes for any endeavour - the more people that attempt the Everest ascent, the more climbers that get into difficulty. So for chipamps, its a red herring.
Reduced compared to a single unparalleled amp? Are you claiming that someone has found that a single LM3886 driving a 2R load sounds better than two paralleled well gain-matched LM3886s driving the same load? If so, please find me the link, I'd like to have a read (and probably a laugh).
If people blindly follow that NS application note then I agree. What do you propose are the alternatives for getting higher power? Discrete designs? They're an order of magnitude more difficult to get working at higher power levels - I've tried both and know for sure which I prefer.
I have no such example. The 370W was your figure not mine. My example was 450W/4R in bridged.
I simply paralleled four existing 2 * 100W designs. So no, the complexity was greatly reduced by being modularised. A fully discrete amp would have required five or six paralleled bipolars to get good linearity and dissipation sharing. Results of that would not be guaranteed either.
I do accept that chipamps suit higher impedance loads and low power. They also suit paralleling very well. Your arguments against paralleling simply don't hold water. Nothing wrong with National's driver stage, I just have no experience with it so I'll be sticking with what I know. Knowing discrete amps as I do, I'm steering away from them for the power levels I'm looking at.
Which of my remarks seem contemptuous to you? My spirit in writing is not to teach AndrewT anything, just to have fun myself. As a teacher, I'm of the view that everyone is self-taught.
Yes, hopefully he'll respond to my remarks in the spirit they were intended in. But somehow, I doubt it
P.S. I liked your remark that 'good grounding is key'. That's a crucial advantage that bridging gives - much harder to screw up the grounding with no large ground return currents.
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Stk amps
I still have a great respect for these chips specially the ones released by Sanyo in the early 2000`s.Class AB to perfected to the max on a small form factor (using thich hybrid tech) like the size of a credit card making the audio paths extremely short eliminating much noise pickups and capacitance effects.
the STK 412-1xx series incoporated high Power MOSFETS outputs in the power stages pefecting the design with class G power efficeincy.
the STK 412-170 in particular can deliver more than 200w in 4 ohm easily at very low levels of THD.
However Sanyo does not make them anymore and market is actually flooded with fakes.
checkout -http://new.taringa.net/posts/info/2024207/Por-que-los-Equipos-Reparados-Vuelven-al-Service.html
I`m glad i did purchase lots of these genunine units these back then .
If are interested in the real thing pls drop me a mail at franbargain@yahoo.com..i beleive i do have the matching boards too!..
I still have a great respect for these chips specially the ones released by Sanyo in the early 2000`s.Class AB to perfected to the max on a small form factor (using thich hybrid tech) like the size of a credit card making the audio paths extremely short eliminating much noise pickups and capacitance effects.
the STK 412-1xx series incoporated high Power MOSFETS outputs in the power stages pefecting the design with class G power efficeincy.
the STK 412-170 in particular can deliver more than 200w in 4 ohm easily at very low levels of THD.
However Sanyo does not make them anymore and market is actually flooded with fakes.
checkout -http://new.taringa.net/posts/info/2024207/Por-que-los-Equipos-Reparados-Vuelven-al-Service.html
I`m glad i did purchase lots of these genunine units these back then .
If are interested in the real thing pls drop me a mail at franbargain@yahoo.com..i beleive i do have the matching boards too!..
I've also bought 2 BrianGT MiniA psu, how did you connect PG+ and PG- located on the LM3886 amp board to the PSU board ?
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