There are people, who claim that there is no perceivable difference at all from one amplifier to another, as long as the frequency response is linear and total harmonic distortion is below 0,1 %. Reality is a bit more complex however.
On the other hand there are people, who pay more than 1500 US$ for the original Gaincard, because it obviously does sound better to them, than anything else at that price.
Then there are mediocre amplifiers that also use the same IC, so it depends on what you make of it.
The only way to find out, if it is an improvement is to build one and listen to it. Maybe start with two channels and compare it to your Pioneer. Then decide, if you build the remaining channels or sell the first two on ebay. You have little to lose, but a lot of fun to gain, because amplifier building can be as much fun as listening to them. Be warned, it may even be addictive.
On the other hand there are people, who pay more than 1500 US$ for the original Gaincard, because it obviously does sound better to them, than anything else at that price.
Then there are mediocre amplifiers that also use the same IC, so it depends on what you make of it.
The only way to find out, if it is an improvement is to build one and listen to it. Maybe start with two channels and compare it to your Pioneer. Then decide, if you build the remaining channels or sell the first two on ebay. You have little to lose, but a lot of fun to gain, because amplifier building can be as much fun as listening to them. Be warned, it may even be addictive.
I'm also wondering if something like this - http://www.circuitspecialists.com/prod.itml/icOid/1309 - would be a good fit for a chassis, with the chips attached to the chassis, and heatsinked to the outside. It's made of steel.
http://diyaudioprojects.com/Chip/Synergy-LM3875-Gainclone/
I'm looking at building this design now, and am wondering about the schematic. I believe I understand it except for the capacitors. I see two spots with 'C's and to the right a list of capacitors, but I'm not sure how the two correlate. Sorry for all the posts, I don't seem to have an 'edit' function available to me.
I'm looking at building this design now, and am wondering about the schematic. I believe I understand it except for the capacitors. I see two spots with 'C's and to the right a list of capacitors, but I'm not sure how the two correlate. Sorry for all the posts, I don't seem to have an 'edit' function available to me.
A transformer can supply as many ICs as his VA rating allows. If sufficiently big, you can use one transformer for all 5 ICs.krips said:
Depends on what you fit in. How big is the transformer (or are the transformers)? How big are the capacitors and how many are there? It helps to draw everything up before ordering a case. Or to get all components and lay them out on a table to measure how much space they really need.krips said:
For the heatsinking you need a low thermal resistance. So it is better to attach the ICs directly (with thermal grease and/or appropriate washers, e. g. mica) to the heatsinks and make approprate holes in the case. Then attach the heatsinks to the case with thermal grease to make use of its additional heatsinking capacity.
It is a very reduced design with no DC protection. Before you use that, make sure that your sources don't deliver DC to the amplifier.krips said:
I'm not sure I understand the difference between this design and others. Would this design http://www.national.com/images/pf/LM3875/01144901.pdf be safe for me to build on my first go?
it's moving in the right direction, but missing three capacitors.krips said:
750nF DC blocking on the input between the wiper and the series resistor Rb.
An RF attenuating capacitor (330pF to 1nF) pin7 to the signal ground.
In addition add a Zin resistor (20k) parallel to that RF cap i.e. from pin7 to signal ground.
Connect the ground symbol below the Ci cap to the signal ground at the source.
Do not connect any of the other power ground symbols at Cs1 or Cs2 or the speaker load to the signal ground. These all go to the Audio ground.
Now add an Rz resistor (4r7) from output to Cz the Zobel capacitor (100nF) and connect Cz to the power ground/audio ground.
Finally connect the signal ground to the audio ground with a 10r resistor.
This amp will sound bass light. try experimenting with DC blocking cap and Ci. Increase to 4u7F and 150uF and compare to your first build reference.
Snubbers are against interference. In a power supply they would e. g. be put across the diodes to work against their ringing. Exact values are determined either by measuring the circuit and calculating the correct value or by Trial-&-Error.krips said:
Small capacitors across bigger capacitors are there to decrease the overall impedance. Although we tend to call them snubbers, they are not really snubbers. The rule of thumb there is that the smaller capacitors should have ~1 % of the bigger capacitor's value.
1x1000 µF could work as well as 1x10000 µF with a smaller cap across it. The trouble with many small caps is that they have tolerances that lead to equalizing current between them. If they become too big, capacitors tend to blow up. There is a thread about such a configuration. You should try to avoid too many capacitors in parallel.
Depends on the value. You can cascade them. E. g. a 10000 µF elco in parallel with a 100 µF elco and a 1 µF ceramic or plastic film capacitor.krips said:
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