Hey Apex audio
can i use this gain clone to run this type of speakers at home?
what is the sensitivity of input?
how much input signal voltage required to get full power output?
JBL GT6-S266
can i use this gain clone to run this type of speakers at home?
what is the sensitivity of input?
how much input signal voltage required to get full power output?
JBL GT6-S266
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Hi Andrew
93dB does not sufficient for home listening?? Then tell me how much SPL should be required for home listening
and LM3886 doesn't support 4ohms load??
This is disappointing to say the least, I am in the process of collecting parts for a lm3886 based amplifier that is going to be used with 4ohm speakers
Most speaker manufactors show very optimistic technical data. As this a car speaker, the 93 dB can relate to a distance of 0.5 meter. Nominal impedance is 4 ohm, 2.83 V is than 2 W.
A chipamp based on LM 3886 can drive a 4 ohm load. I could be adviceable to use a slightly lower supply voltage.
I used a 22v transformer for my lm4780 build as recommended with the intention of using it with a 6ohm pair of speakers and a 4ohm pair. It seems to me Andrew is saying that these chips cannot be used with 4ohm speakers no matter what amount of voltage is applied.
P.s. I am listening to my lm4780 with 4ohm klipsch kg4s right now and it sounds delightful. Some more discussion or explanation of this topic would be appreciated.
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Look at the datasheet and see the problem.
Then decide what you as the designer can do to help the chipamp perform well.
If that means using a lower voltage to keep the chip cooler and using a lower voltage to reduce the current that will be demanded and using high efficiency speakers to reduce the current demand, then you can get good performance from chipamps.
Look at Peter Daniels results. He uses ~95dB/W 4ohm speaker. So it can be done, but you must inform yourself and then design for the chipamp limitations.
For me, the easy way is keep the chipamp cool and use 8ohms or higher speakers.
Then decide what you as the designer can do to help the chipamp perform well.
If that means using a lower voltage to keep the chip cooler and using a lower voltage to reduce the current that will be demanded and using high efficiency speakers to reduce the current demand, then you can get good performance from chipamps.
Look at Peter Daniels results. He uses ~95dB/W 4ohm speaker. So it can be done, but you must inform yourself and then design for the chipamp limitations.
For me, the easy way is keep the chipamp cool and use 8ohms or higher speakers.
Surely, if your power requirement is not too demanding, there is no reason why you cannot use the 4780 with 4R speakers.
Or if you need more power, use 2 in bridge or parallel mode.
I am intending to use 2 pairs of them driven differentially from the output of my dual differential tda1541a dac's Sowter I/V transformers. (This also removes any DAC output offsets.)
There are twin secondaries which will provide anti phase outputs so both amps are connected in non inverting mode with the speaker connected in bridge configuration.
For volume control I intend varying the gain - I always seem to listen with the volume control on my current setup rarely being adjusted, so the transformer secondaries will be directly coupled to the inputs, probably with a load resistor across them.
Ian
this changes the gain and phase margins.
That will change the output signal (it won't mimic the input signal) and could result in instability, or worse, oscillation.
You missed by point about only varying the gain a relatively small amount - far less than a conventional pot on the input would. The adjustment is more to cater for variations between CDs.
If I decide I need more volume adjustment then I'd use:-
SOWTER ATTENUATOR TRANSFORMERS TVC VOLUME CONTROL
I
Is the circuit used in this PCB is same as in the Datasheet of LM3886? if not there would be any loss of quality of sound,power,frequency range etc
can i use this speakers for home on this amplifier
http://www.indiajbl.com/CarAudioDesc.aspx?ID=110
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The pcb layout is not critical for audio circuits so there won't be any loss of quality if the schematic is not the same as the datasheet.
You might consider using two LM4780 dual chipamps which can be run with the amps paralleled for more current for 4ohm speakers.
Car speakers are designed for use in a small volume and will not be very good for home use unless your listening room is very small. You will also have to design a cabinet for them using the Thiele Small parameters which are not shown.
In a vehicle, you are actually sitting inside the louspeaker cabinet and it is the pressure changes that transmit much of the sound. (which is why you feel the bass in a car more than you do in your listening room).
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