Hum
Hi Brian
You are using graundplane right ?
How is R51 mounted ?? I haven't mounted it, and it seams to give a littel bit of hum. I can hert it if i the room is silent, and no signal i connected to the input.
Also the input cap seems to suffer from "mikrofonia" (If I tap it, there is a sound in the speaker). What type do you use ?
How is your ground layed out ?
\Jens
Hi Brian
You are using graundplane right ?
How is R51 mounted ?? I haven't mounted it, and it seams to give a littel bit of hum. I can hert it if i the room is silent, and no signal i connected to the input.
Also the input cap seems to suffer from "mikrofonia" (If I tap it, there is a sound in the speaker). What type do you use ?
How is your ground layed out ?
\Jens
Jens:
>>b) The large caps<<
Right, caps at 0 voltage act pretty much like a dead short when the transformer turns on.
I'm looking at this issue now, I want to use a 1000va or 1500va amp for my 6-10 channel home theater project; I'm worried about inrush.
When looking at relays for output protection and turn on thump, I started thinking of using a capacitor bank, and then switching each set of cap's with a few relays on a timer. If I used DPDP relays, you could even use a fairly large resistor then when the caps get charged, they would self - power the relay to cut out the resistor.
On another thread there are some thermistor examples for the same thing, but I'd like to avoid the heat if possible.
Sorry for disgressing on the thread in answering the question.
The amp looks fantastic, by the way!
>>b) The large caps<<
Right, caps at 0 voltage act pretty much like a dead short when the transformer turns on.
I'm looking at this issue now, I want to use a 1000va or 1500va amp for my 6-10 channel home theater project; I'm worried about inrush.
When looking at relays for output protection and turn on thump, I started thinking of using a capacitor bank, and then switching each set of cap's with a few relays on a timer. If I used DPDP relays, you could even use a fairly large resistor then when the caps get charged, they would self - power the relay to cut out the resistor.
On another thread there are some thermistor examples for the same thing, but I'd like to avoid the heat if possible.
Sorry for disgressing on the thread in answering the question.
The amp looks fantastic, by the way!
Sorry for the long delay in details with the board. I will get them made, but I have been distracted by my speaker and subwoofer projects. I also have been quite busy with work. I have verified that the board works, but I would like to do some more testing of the board before getting them made, comparing it to the normal leach amp. I will try to go into lab and test them soon.
Once that is done, it will take two weeks to get the boards made.
--
Brian
Once that is done, it will take two weeks to get the boards made.
--
Brian
Listening to a Leach amp
Hi
I'v solved the hum problem, turns out it was because of a bad ground connection.
Does anybody know what sort of Qpoint current in each transistor is the best? I have tried 30 mA and 50 mA, and the last i clearly the better. What do you use?
\Jens
Hi
I'v solved the hum problem, turns out it was because of a bad ground connection.
Does anybody know what sort of Qpoint current in each transistor is the best? I have tried 30 mA and 50 mA, and the last i clearly the better. What do you use?
\Jens
BrianGT said:I have verified that the board works, but I would like to do some more testing of the board before getting them made, comparing it to the normal leach amp. I will try to go into lab and test them soon.
Once that is done, it will take two weeks to get the boards made.
--
Brian
Hi!
Have you tested the boards and get them made?
I can't wait to get my hands on them
....and what about the price for a pair of boards?
mario
I think you may be asking for trouble with the pair you list.
Use either the 2SC3281 and its complement (2SA1302) OR the 2SA1943 and its complement (? I don't remember). Don't mix.
mlloyd1
Use either the 2SC3281 and its complement (2SA1302) OR the 2SA1943 and its complement (? I don't remember). Don't mix.
mlloyd1
jarek said:Hi ALL!
I'm going to rebuild may Leach amp with 2SC3281/2SA1943. These transistors have high Ft (>30Mhz). What do you think about omitting 'split feedback' and picking it all exactly from the output?
Sorry, my mistake. I thought about 2SA1943 and 2SC5200.I think you may be asking for trouble with the pair you list.
Use either the 2SC3281 and its complement (2SA1302) OR the 2SA1943 and its complement (? I don't remember). Don't mix.
Leach feedback
Hi
Snip
What do you think about omitting 'split feedback' and picking it all exactly from the output
snip
I have tried simulating alot of different feedbackconfigurations on the Leach, how do you mean? No feedback from predriver? or short the middle of the drivers to the output?
\Jens
Hi
Snip
What do you think about omitting 'split feedback' and picking it all exactly from the output
snip
I have tried simulating alot of different feedbackconfigurations on the Leach, how do you mean? No feedback from predriver? or short the middle of the drivers to the output?
\Jens
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