You know, it is an old story.... audiophiles are everytime standing in two "camp" and fighting. There are some people how prefer the regulated PSU in power amps and there are some who not. Like me.
You can find many literature about PSU. One of the best is here:
http://www.tnt-audio.com/clinica/ssps1_e.html
I didn't try regulated PSU for my Choke Loaded Amp, because I knew it already that I don't like them. With the Hiraga Monster and JLH69 (etc.) the sound was a bit "thiner" the dynamic a bit weaker and lifeless than with unregulated PSU.
Yes!
Ryssen!
Don't mix the two amp! The Choke Loaded Amp is different from the original SEWA. It needs much less power. It has near 50% efficiency!
I built the original SEWA with 300VA too, and mine was not hot....
Greets:
Tyimo
I didn't try regulated PSU for my Choke Loaded Amp, because I knew it already that I don't like them. With the Hiraga Monster and JLH69 (etc.) the sound was a bit "thiner" the dynamic a bit weaker and lifeless than with unregulated PSU.
Hi Tyimo,
Thel Audio is telling the same that's why that their regulated supplys don't work so tight voltagefall or is it rimple of 40mV/Amp
If you can read German see here www.thel.de.A tight regulated supply don't sound well.A convencial supply sounds the best.The reason is that regulated supplys don't like big supply caps because they are to tight.Thel Audio's supply is made special for audio-amps.
Hi Tyimo,
Thel Audio is telling the same that's why that their regulated supplys don't work so tight voltagefall or is it rimple of 40mV/Amp
If you can read German see here www.thel.de.A tight regulated supply don't sound well.A convencial supply sounds the best.The reason is that regulated supplys don't like big supply caps because they are to tight.Thel Audio's supply is made special for audio-amps.
HI Ryssen
I built several Hiraga Class A but I did never like the sound until I used Capacitante Multiplier power supply .
But instead of 4700Mf or 10 000 I used 60 000Mf of course I use soft starter because it would kill the transformer.
It is very sensitive what type of transistors I use !!!!!
For me the best power supply at the Class A Hiraga .
I didn't tried with another amp like Aleph X , A30 etc .
Maybe you give a try in another amp !?
Regards
I built several Hiraga Class A but I did never like the sound until I used Capacitante Multiplier power supply .
But instead of 4700Mf or 10 000 I used 60 000Mf of course I use soft starter because it would kill the transformer.
It is very sensitive what type of transistors I use !!!!!
For me the best power supply at the Class A Hiraga .
I didn't tried with another amp like Aleph X , A30 etc .
Maybe you give a try in another amp !?
Regards
Mad and thier friends, i`ve read every single thing on this topic sewa 7 watts, and today im buit it and the sound is really clear, i only test it with to-220 irf540n, and the sound is amazing. i would like to know how to parallels mosfets ics, mads or thier friends here maybe can help me to find out with it,
If we do parallels,does the power 7 watts will increase? like 20 or something,
what about the heat, it will increase or decrease?
about power supply, no change?
any help much appreciate it.
regards.
If we do parallels,does the power 7 watts will increase? like 20 or something,
what about the heat, it will increase or decrease?
about power supply, no change?
any help much appreciate it.
regards.
Hello.
I suggest the same modification on the sewa as Ladislav Bunta did on the power Follower of Pavel Macura. The Bipolar Transistor. The sound will be more relaxed and fine:
And my proposals:
Connect the grounds of the Q2 of the sewa.
Do not use channel separate PSUs. Never and nowhere.
The sound of the sewa in general comparision to the power follower of Macura (in my mind!):
It seems, the sewa has more „black“, more focus, he is more present and living, but he is a little bit restless, „brittle“, scruff.
The Macura seems to be more relaxed and quiet, more fine and clear, extended, but not so present and alive.
But this is only my experience!
Best regards.
C.
I suggest the same modification on the sewa as Ladislav Bunta did on the power Follower of Pavel Macura. The Bipolar Transistor. The sound will be more relaxed and fine:
An externally hosted image should be here but it was not working when we last tested it.
And my proposals:
Connect the grounds of the Q2 of the sewa.
Do not use channel separate PSUs. Never and nowhere.
The sound of the sewa in general comparision to the power follower of Macura (in my mind!):
It seems, the sewa has more „black“, more focus, he is more present and living, but he is a little bit restless, „brittle“, scruff.
The Macura seems to be more relaxed and quiet, more fine and clear, extended, but not so present and alive.
But this is only my experience!
Best regards.
C.
Hi,
I've built one of the more original versions (somewhere around page 13) with the two IRF240 MOSFETS... the bottom one acting as the current sink.
How much heatsink does this thing need? I'm tripping the 85C. thermal on a 8" x 4" x 1" fin 2Lb chunk of aluminum in about 10 minutes
Cold she draws ~2.5A per channel with the DC output to the capacitor exactly at Vdd/2. In two minutes, it's sucking 4A/channel with the output DC bias at ~1/3 Vdd and it just starts roasting the source bias resistors. At 5 minutes, you can't touch the heatsink and at 8-10 minutes, the thermal breaker (a scavenged keep-warm switch from a coffee maker) goes "click".
I cut the power and let it cool, I can repeat this.
She amplifies a sinewave cleanly into 8 ohms on the 'scope the whole time until I pull the plug.
The output caps aren't leaky.
I thought MOSFETS didn't have thermal runaway issues?
Cheers!
I've built one of the more original versions (somewhere around page 13) with the two IRF240 MOSFETS... the bottom one acting as the current sink.
How much heatsink does this thing need? I'm tripping the 85C. thermal on a 8" x 4" x 1" fin 2Lb chunk of aluminum in about 10 minutes
Cold she draws ~2.5A per channel with the DC output to the capacitor exactly at Vdd/2. In two minutes, it's sucking 4A/channel with the output DC bias at ~1/3 Vdd and it just starts roasting the source bias resistors. At 5 minutes, you can't touch the heatsink and at 8-10 minutes, the thermal breaker (a scavenged keep-warm switch from a coffee maker) goes "click".
I cut the power and let it cool, I can repeat this.
She amplifies a sinewave cleanly into 8 ohms on the 'scope the whole time until I pull the plug.
The output caps aren't leaky.
I thought MOSFETS didn't have thermal runaway issues?
Cheers!
Hi,
Here it is. I think that reads 8.5 deg/W.
I've mounted all four transistors (two channels) on the one sink. But even as I tested it mono with just the two, I was having overheating issues and decided to add forced air cooling later.
I have not set the current at 4A. It's set at 2.5A. It creeps up
Cheers!
Here it is. I think that reads 8.5 deg/W.
I've mounted all four transistors (two channels) on the one sink. But even as I tested it mono with just the two, I was having overheating issues and decided to add forced air cooling later.
I have not set the current at 4A. It's set at 2.5A. It creeps up
Cheers!
Attachments
It reads 0,5'C/W. What rating are your HS? What is your rail voltage? You need 0,25'C/W (@100W) for 2 channels if assembled as per that schematic.
Sounds to me like thermal runaway. To test this, try to use just one 1,5ohm resistor (R12, leave R13-16 Not Mounted)
You should now get a stable 0,4A bias. If still unstable, it might also be that the current sink is unstable, try adding a 100-1000pF cap across Q3 Base and Collector.
Sounds to me like thermal runaway. To test this, try to use just one 1,5ohm resistor (R12, leave R13-16 Not Mounted)
You should now get a stable 0,4A bias. If still unstable, it might also be that the current sink is unstable, try adding a 100-1000pF cap across Q3 Base and Collector.
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