Rod Elliot said it quite loud in his Death of Zen power amp page. It's the test circuit he experimented with; using an NPN darlington as the power device and an 8ohm resistor as the current source. He seems quite unsatisfied with the output of this amp at its original state and noted that there will be chages in the final circuit. There were big changes including the omission of the darlington as they are slow. Everything went fine and the DoZ amp was born. I have made a couple of DoZ and it's an exceptional amp with unmatched sound quality, I like the amp. Link> Death of Zen - A new Class-A power amp
So far so good.
A couple of days ago I was going through that project page again and got stuck on that "STOP!". The test circuit seemed to me as workable with only the addition of a constant current source in the place of the 8ohm current source resistor. I added one, following the way the CCS is designed in the DoZ Preamplifier, using a PNP darlington and a BC560.
Expecting NOTHING special I assembled it and powered it up.
The amp really sounds nothing special, EXCEPT when I start varying the VR1. Damn funny things start to happen while I increase or decrease its value. Rod explains how the amount of distortion in this amp's output almost directly relates to the value of this resistor.
What I felt was that when the resistance of VR1 is set to high, the amp starts creating strange clipping behaviour, which sounds good to me when there is a little of it. Of course too much of it makes the sound gross and low volume and at 10Kohm almost nothing is heard.
The main source of fun right now is this resistor. At high, medium and low value this resistor makes this amp sound Distorted like an overdriven valve amp, Sweet like any SE amp, and Clean like a Hi-Fi respectively. You get the idea.
However, I believe you already know what this ameteur is babbling about.
Well, I am here to say thanks to the diyAudio community from where I have gained a lot of knowledge and enough courage to do experiment with existing ideas.
So far so good.
A couple of days ago I was going through that project page again and got stuck on that "STOP!". The test circuit seemed to me as workable with only the addition of a constant current source in the place of the 8ohm current source resistor. I added one, following the way the CCS is designed in the DoZ Preamplifier, using a PNP darlington and a BC560.
Expecting NOTHING special I assembled it and powered it up.
The amp really sounds nothing special, EXCEPT when I start varying the VR1. Damn funny things start to happen while I increase or decrease its value. Rod explains how the amount of distortion in this amp's output almost directly relates to the value of this resistor.
What I felt was that when the resistance of VR1 is set to high, the amp starts creating strange clipping behaviour, which sounds good to me when there is a little of it. Of course too much of it makes the sound gross and low volume and at 10Kohm almost nothing is heard.
The main source of fun right now is this resistor. At high, medium and low value this resistor makes this amp sound Distorted like an overdriven valve amp, Sweet like any SE amp, and Clean like a Hi-Fi respectively. You get the idea.
However, I believe you already know what this ameteur is babbling about.
Well, I am here to say thanks to the diyAudio community from where I have gained a lot of knowledge and enough courage to do experiment with existing ideas.
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