I recently built a 600watt 4ohm amplifier with a 5kva power supply. When I turn it on, the lights quickly dim out like I expect, but I hear absolutely nothing, just utter silence, and there's no hiss even right close to my speaker. I know the amp is working fine cause I've loaded it down to 1.3ohms and run at about 1100watts no problem at all. It get's hot but that's to be expected... All I wonder about is, "Is it normal for a simple project amp to be so good that it stabilizes instantly and has no DC offset whatsoever, even just biased with a voltage divider/diode network???
Duo,
Congratulations! Fantastic job.
My experience is that most amplifiers behave differently at switch on, with different power supplies. If you were to have a totally different power supply for the amp that you describe, it could show some turn on thump. It depends on the variables at play and the intensity of the thump tends to vary.
By the way, which circuit did you use. Is it your own design or some well known design, modified. Especially, the loading down to 1.3 ohms sounds very interesting (read, intriguing). If you don't mind, could you please provide some details here. Thanks.
Congratulations! Fantastic job.
My experience is that most amplifiers behave differently at switch on, with different power supplies. If you were to have a totally different power supply for the amp that you describe, it could show some turn on thump. It depends on the variables at play and the intensity of the thump tends to vary.
By the way, which circuit did you use. Is it your own design or some well known design, modified. Especially, the loading down to 1.3 ohms sounds very interesting (read, intriguing). If you don't mind, could you please provide some details here. Thanks.
Roddyama: yes, it dims all the lights on it's circuit, the pwr supply is 5kva so it takes a lot to get the transformer going. Also, when running into 1.3 ohms, it could almost shut the lights off if I had enough speakers to put on it.
Samuel Jayaraj: I will provide some more info when I can draw I diagram on the computer. The amp right now is just a big buffer with out much for a VAS stage. I hard wired it with 10 gauge solid copper wire so there is minimal current loss and you can't accidentaly bend the wires out of place without pliers. The design is very much similar in the output stage to ESP project 3A, But the rest is my own ideas. I never thought the amp would be so stable into such heavy loads, especiall since the supply voltage is 160volts rail to rail and it's my first amp! however, It has excellent sonic quality and I plan to make lots of documentation on it soon so keep your eye on here.
Samuel Jayaraj: I will provide some more info when I can draw I diagram on the computer. The amp right now is just a big buffer with out much for a VAS stage. I hard wired it with 10 gauge solid copper wire so there is minimal current loss and you can't accidentaly bend the wires out of place without pliers. The design is very much similar in the output stage to ESP project 3A, But the rest is my own ideas. I never thought the amp would be so stable into such heavy loads, especiall since the supply voltage is 160volts rail to rail and it's my first amp! however, It has excellent sonic quality and I plan to make lots of documentation on it soon so keep your eye on here.
Well... not nessecarily, rarely you'll find an amp that stabilizes instantaneously upon application of power. You can usually hear some kind of little blurp or tick when you turn it on, but mine is silent. Once in a while, I can turn it on and it might make a very very quiet blip noise but it's not even an 8th of a second long and you can barely hear it even if it does make a bit of noise.
by the way guys, I remember the numbers on the transistors I used for output now. The main O/T's operate in push pull and use 3 each of B688 and D718, operating with compound pair drivers. Today I ran the amp steady into 2ohms for about an hour with about 35volts output and got enough undistorted volume to make the garage door visibly shake and the lights flash quite a bit. It was actually, believe it or not, too loud for me to sit right in front of the speakers, I had to stand off to the side or outside of the garage or I just couldn't handle it.
I'm amazed I've gotten these specific transistors to handle a two ohm load through steady music using power supply rails of +-80 volts... What do you guys think about this? Do you think these particular transistors should normally handle this in this kind of design???
by the way guys, I remember the numbers on the transistors I used for output now. The main O/T's operate in push pull and use 3 each of B688 and D718, operating with compound pair drivers. Today I ran the amp steady into 2ohms for about an hour with about 35volts output and got enough undistorted volume to make the garage door visibly shake and the lights flash quite a bit. It was actually, believe it or not, too loud for me to sit right in front of the speakers, I had to stand off to the side or outside of the garage or I just couldn't handle it.
I'm amazed I've gotten these specific transistors to handle a two ohm load through steady music using power supply rails of +-80 volts... What do you guys think about this? Do you think these particular transistors should normally handle this in this kind of design???
Heh, this debate went offtopic
I removed delay relay from my (I built it 2days ago) leach amp and it appears that I dont have turn on thump too.. Is it because I used softstart for toroid and the caps gets some charge in that 1s, when toroid is running in series with resistor?
Duo, are you using soft start for toroid?
I removed delay relay from my (I built it 2days ago) leach amp and it appears that I dont have turn on thump too.. Is it because I used softstart for toroid and the caps gets some charge in that 1s, when toroid is running in series with resistor?
Duo, are you using soft start for toroid?
Leach Amp - no thump ?
For the Leach amp, I seem to remember reading that Dr. Leach says the amp doesn't have thump because the diff amp stages current sources/sinks have significant R/C time constants as opposed to the instantaneous start up operation of the fancier current sources/sinks.
Soft start for the power tranny is a good thing, too.
mlloyd1
For the Leach amp, I seem to remember reading that Dr. Leach says the amp doesn't have thump because the diff amp stages current sources/sinks have significant R/C time constants as opposed to the instantaneous start up operation of the fancier current sources/sinks.
Soft start for the power tranny is a good thing, too.
mlloyd1
skaara said:Heh, this debate went offtopic
I removed delay relay from my (I built it 2days ago) leach amp and it appears that I dont have turn on thump too.. Is it because I used softstart for toroid and the caps gets some charge in that 1s, when toroid is running in series with resistor?
Duo, are you using soft start for toroid?
Well, I'm not saying his flying is bad, it's just that a pilot rarely needs to hold the yoke so tightly. So anyway, that out of the air(no pun intended) Who is the pilot??? May we know??
By the way, somebody asked if I was using a soft start toroid: No, it's not even a normal toroid, I'm using a 5kva Delta power isolation transformer for the power supply. I don't need any sort of step down cause the rails are supposed to be 160 volts anyway, so this trannie is perfect!
By the way, somebody asked if I was using a soft start toroid: No, it's not even a normal toroid, I'm using a 5kva Delta power isolation transformer for the power supply. I don't need any sort of step down cause the rails are supposed to be 160 volts anyway, so this trannie is perfect!
Roddyama: I must ask, exactly how does a kamikaze pilot pull of that many missions? In the dictionary, kamikaze is a pilot trained in WWII to perform a suicide mission, this doesn't exactly equate to the possibility of 47 successful missions if he's to actually complete them in the usual way, does it?
EDIT: I do suppose if I were to commit suicide in a jet, I'd hold the yoke pretty darn tight as well!
EDIT: I do suppose if I were to commit suicide in a jet, I'd hold the yoke pretty darn tight as well!
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