I recently picked up a diy zen amplifier that is missing it's power transformer. I have an amp with a EI transformer I hooked up to test the amp but I don't feel like cannibalizing one amp to make this one complete. Now I am a crossroads. Do I buy a transformer and just complete the amp or for about the same money do I try a resonant SMPS like the one here or reviewed here. Has anyone done a good write up comparing the same amp circuit on a linear and SMPS PS? Considering that a later modification to the zen amplifier series is a regulated PS, I would think the SMPS would be a great way to go. Does anyone else have an opinion on this?
I understand they will both sound different. If I expected them to sound the same, I would just buy the cheapest. I was hoping that I wouldn't be the first one going down this path and that someone could give me some anecdotal information. My hunch is that SMPSs have reached the point of outperforming linear PSs when properly built. They generally have low output impedance and can source current very fast. I am still very much an amateur though so I don't want to end up spending money on the SMPS to find out that it is to noisy to use or has some other issues I am not able to overcome.
If I had the money to spend I would buy an smps and build a linear one to a/b. I still could do that using the transformer from my other amp I guess. I am leaning towards the smps but want to be 100% sure I am not tossing the money out the window as I would have no other use for it currently.
If I had the money to spend I would buy an smps and build a linear one to a/b. I still could do that using the transformer from my other amp I guess. I am leaning towards the smps but want to be 100% sure I am not tossing the money out the window as I would have no other use for it currently.
Reading your original post again make me as a question - Because you have cannibalized a different amp to get the Zen working, why don't you get the SPMS and determine in which of the 2 amps the linear sounds better and then where the SMPS is better.
This way you get to mess with 2 amps and get twice the experience with the SMPS.
This way you get to mess with 2 amps and get twice the experience with the SMPS.
A simple zener type shunt regulated supply or a capacitance multiplier is more "Zen" than either a switched capacitor supply or a supply with negative feedback. Why?
Because although the simple designs may need huge capacitors to bring the ripple down, with A class amps, the AC load current varies linearly with the audio signal and the full wave audio signal super-imposed on the PSU output has no effect on amplifier distortion.
My choice would be to replace the transformer and use a capacitance multiplier. You should be able to achieve <5mV ripple.
Because although the simple designs may need huge capacitors to bring the ripple down, with A class amps, the AC load current varies linearly with the audio signal and the full wave audio signal super-imposed on the PSU output has no effect on amplifier distortion.
My choice would be to replace the transformer and use a capacitance multiplier. You should be able to achieve <5mV ripple.
Could someone tell me the maximum ripple the zen circuit can handle. I know that I could just build a linear PS and get a nice low number but I think I want to try this SMPS and share my findings. I am worried that 200mV is going to be to much. If you could explain the math that determines this, I would be even more grateful 
So I finally got my SMPS in today. I am going to first see if the smps is ok by itself but I may try adding a CL filter after the smps to reduce any noise/harmonics. The SMPS can handle 15000uf on it's outputs and I would be using 2 10,000uf in parallel if I go this route. I'll keep things updated as I go along.
Well now both channels are broken. I think I am going to take a break today.
I replaced the 9140 with a 9240 I had on hand. It blew as well so I am guessing I have a problem somewhere else. I am guessing that I have a problem with the 140 or the MPSA92 but I am not 100 percent sure. I guess I will have to pull the board out and test both. Considering I was able to play this amp with a linear supply, what could be causing me to blow out components with the SMPS? The SMPS has a higher V+ then what the circuit calls for originally but later zen versions used higher V+ power supplies so I am not sure that is the problem. This link seems to say I should be ok as well. Could the higher V be pushing the I through MPSA92 past it's 500mA limit? Would switching the a ZTX550 improve things?
One side questions. With the SMPS, could I remove the 2 10,000uf caps on the board and still be ok? Are these guys doing anything besides ripple filtering?
I replaced the 9140 with a 9240 I had on hand. It blew as well so I am guessing I have a problem somewhere else. I am guessing that I have a problem with the 140 or the MPSA92 but I am not 100 percent sure. I guess I will have to pull the board out and test both. Considering I was able to play this amp with a linear supply, what could be causing me to blow out components with the SMPS? The SMPS has a higher V+ then what the circuit calls for originally but later zen versions used higher V+ power supplies so I am not sure that is the problem. This link seems to say I should be ok as well. Could the higher V be pushing the I through MPSA92 past it's 500mA limit? Would switching the a ZTX550 improve things?
One side questions. With the SMPS, could I remove the 2 10,000uf caps on the board and still be ok? Are these guys doing anything besides ripple filtering?
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