Hi Circlotron and Hitsware
Yes, the ringing overshoot is something that needs to be tamed (however the point of the picture was the almost ruler flat square wave top and bottom at 50 watts, rather then the ringing).
Part of the problem is on the input transformer secondaries to the mosfet gates.
I have the Mumetal laminations ordered and they should have been posted on Friday.
I was holding off doing anything further until I could sit down and try out all three combinations:
M6 - current configuration.
50/50 M6/Mumetal.
100% Mumetal.
From what I understand of these things the 50/50 is likely to be the one I will go for, but I would like to actually see it on the bench as these things can still surprise....
(pause)
Ah, post has just arrived - and with it my Mumetal laminations 🙂
After all the problems with the post here in London in recent months, getting things next day (and they actually arrive rather than being stolen) is somewhat of a novelty.
So if you will excuse me I have some testing to do.
Best wishes,
Susan.
Circlotron said:
hitsware said:
Yes, the ringing overshoot is something that needs to be tamed (however the point of the picture was the almost ruler flat square wave top and bottom at 50 watts, rather then the ringing).
Part of the problem is on the input transformer secondaries to the mosfet gates.
I have the Mumetal laminations ordered and they should have been posted on Friday.
I was holding off doing anything further until I could sit down and try out all three combinations:
M6 - current configuration.
50/50 M6/Mumetal.
100% Mumetal.
From what I understand of these things the 50/50 is likely to be the one I will go for, but I would like to actually see it on the bench as these things can still surprise....
(pause)
Ah, post has just arrived - and with it my Mumetal laminations 🙂
After all the problems with the post here in London in recent months, getting things next day (and they actually arrive rather than being stolen) is somewhat of a novelty.
So if you will excuse me I have some testing to do.
Best wishes,
Susan.
Susan-Parker said:
The weird thing is, the output signal looks flatter than the input signal, lol.
The ringing looks like a 40 kHz harmonic (I think) so you would probably not hear it anyway.
If the problem is the input transformer, you could consider not using one at all, the only problem is the signal ground is not the same as the power supply ground.
Attachments
That ultrasonic ringing...
My 2 cents worth...
You won't hear the ringing, you'll hear the lack of the ringing...
🙂
_-_-bear
My 2 cents worth...
You won't hear the ringing, you'll hear the lack of the ringing...
🙂
_-_-bear
Off topic!
Thanks for the link Bobo10n1,
I keep getting my mails to you back, that's why I'm replying through the forum.
Sorry to all other members.
Audiofanatic 😉🙄
Thanks for the link Bobo10n1,
I keep getting my mails to you back, that's why I'm replying through the forum.
Sorry to all other members.
Audiofanatic 😉🙄
Respectable Comments
Hi SUSAN PARKER,
I have seen ur amp on ur website and then got excited very much about its simplicity, then built it using IRFP250N Mosfets and transformers.
After Hearing the audio output , we were very much delighted and amazed on the concept of zero feedback.
The output has a depth, edge, precision , smooth flow and every thing a amp needs.
Finally,
Kindly accept warm our Congratulations for ur excellent designing of the amp.
Once again we salute ur sheer effort.
With Respect
Workhorse Audio Team.
Hi SUSAN PARKER,
I have seen ur amp on ur website and then got excited very much about its simplicity, then built it using IRFP250N Mosfets and transformers.
After Hearing the audio output , we were very much delighted and amazed on the concept of zero feedback.
The output has a depth, edge, precision , smooth flow and every thing a amp needs.
Finally,
Kindly accept warm our Congratulations for ur excellent designing of the amp.
Once again we salute ur sheer effort.
With Respect
Workhorse Audio Team.
Okay, some progress.
Top trace is 1 kHz 40 volts peak to peak into 8 ohms = 50 watts.
I have fitted a series RC filter across the secondaries of the input transformer where the initial ringing was occurring ( the output stage was just doing what it was told).
With the current values I have
0 dB at 10.0 kHz
-3 dB at 47.7 kHz
-6 dB at 76.3 kHz
However I intend to redo this and put a filter (100 kHz - i.e. 192/24 DAC equivalent?) on the input to the line driver. I will then readjust the transformer RC filter values.
Info added to the square wave test page.
http://www.susan-parker.co.uk/zeus-test-square-1khz.htm
BW,
Susan.
Sorry the pic is a bit blurred - better one in due course.
Top trace is 1 kHz 40 volts peak to peak into 8 ohms = 50 watts.
I have fitted a series RC filter across the secondaries of the input transformer where the initial ringing was occurring ( the output stage was just doing what it was told).
With the current values I have
0 dB at 10.0 kHz
-3 dB at 47.7 kHz
-6 dB at 76.3 kHz
However I intend to redo this and put a filter (100 kHz - i.e. 192/24 DAC equivalent?) on the input to the line driver. I will then readjust the transformer RC filter values.
Info added to the square wave test page.
http://www.susan-parker.co.uk/zeus-test-square-1khz.htm
BW,
Susan.
Sorry the pic is a bit blurred - better one in due course.
Interesting results. Just wondering: The lower curve is that the input signal? If yes, have you trimmed your oscilloscope probe properly?
Have you noticed my title "More is better"? If you would donate some money yours could be "Less is better" 😀
Anyway, it's an interesting amp.
Have you noticed my title "More is better"? If you would donate some money yours could be "Less is better" 😀
Anyway, it's an interesting amp.
Re: Respectable Comments
Hi amp_man_1,
Excellent 🙂
How much power are you running (Not quite "1KW++" I guess)?
Any chance of a picture what you put together?
Best wishes,
Susan.
Hi amp_man_1,
amp_man_1 said:
Excellent 🙂
How much power are you running (Not quite "1KW++" I guess)?
Any chance of a picture what you put together?
Best wishes,
Susan.
Hi peranders,
Yes, my venerable Tek 465 with it's original probes beginning to show its age.
However the timebase is still right on the nail, even at 100 MHz.
Or perhaps "Less is More" 🙂
No - I hadn't really cottoned on to what the extra personal details were about. I have only been on the DIY audio forum for two weeks and I am still finding my way around...
... however it has provided a degree of encouragement with my audio efforts.
I will have a look at the personal stuff and see 🙂
Thanks.
Best wishes,
Susan.
peranders said:
Yes, my venerable Tek 465 with it's original probes beginning to show its age.
However the timebase is still right on the nail, even at 100 MHz.
Or perhaps "Less is More" 🙂
No - I hadn't really cottoned on to what the extra personal details were about. I have only been on the DIY audio forum for two weeks and I am still finding my way around...
... however it has provided a degree of encouragement with my audio efforts.
I will have a look at the personal stuff and see 🙂
Anyway, it's an interesting amp.
Thanks.
Best wishes,
Susan.
Susan,
in case ur not up on this...
to trim the probes, you put them on the internal Cal signal that the scope provides (btw that's a superior signal to use for 1kHz square wave testing! ) and look at the trace... if the probe has a trimmer on it, you dork that for best, flattest and least ringies.
Most of the Tek scopes of your vintage, like mine, have an internal air cap on the board near the vert input jacks which is also used for compensation adjustments... ur manual will tell all...
But the damped square wave looks pretty nifty keen!
I now deem your design "listenable" 😉 heh heh...
My thinking is that the input filter will have little effect on the ringing from the xfmr itself... the interesting thing will be to look at the ringing and note how it differs from xfmr unit 1 to xfmr unit 2 of the same type and design! 🙂 Or, if it differs...
Darn, now I may have to build one too! 😀
_-_-bear
in case ur not up on this...
to trim the probes, you put them on the internal Cal signal that the scope provides (btw that's a superior signal to use for 1kHz square wave testing! ) and look at the trace... if the probe has a trimmer on it, you dork that for best, flattest and least ringies.
Most of the Tek scopes of your vintage, like mine, have an internal air cap on the board near the vert input jacks which is also used for compensation adjustments... ur manual will tell all...
But the damped square wave looks pretty nifty keen!
I now deem your design "listenable" 😉 heh heh...
My thinking is that the input filter will have little effect on the ringing from the xfmr itself... the interesting thing will be to look at the ringing and note how it differs from xfmr unit 1 to xfmr unit 2 of the same type and design! 🙂 Or, if it differs...
Darn, now I may have to build one too! 😀
_-_-bear
Hi bobo1on1
The amplifier was designed to be a mono-block and to sit next to the speaker it was driving.
High power - high currents = short signal path.
Low power - low currents = long signal path.
This has the added benefit of saving on the speaker cable (I use 4mm square x 2 from RS (a electrical/electronics distro), however others use more esoteric stuff like
http://www.vandenhul.com/cable/thrd.htm
at which point you really want to be using as little as possible 🙂
Additionally the input transformer give full isolation from ground loop problems (I have this between a couple of items plugged into the same power point) some setups could be on separate mains phases.
For an integrated amp one could of course use alternatives to the input transformer. But that is more parts, a second rail power supply, etc.
Best wishes,
Susan.
bobo1on1 said:
The amplifier was designed to be a mono-block and to sit next to the speaker it was driving.
High power - high currents = short signal path.
Low power - low currents = long signal path.
This has the added benefit of saving on the speaker cable (I use 4mm square x 2 from RS (a electrical/electronics distro), however others use more esoteric stuff like
http://www.vandenhul.com/cable/thrd.htm
at which point you really want to be using as little as possible 🙂
Additionally the input transformer give full isolation from ground loop problems (I have this between a couple of items plugged into the same power point) some setups could be on separate mains phases.
For an integrated amp one could of course use alternatives to the input transformer. But that is more parts, a second rail power supply, etc.
Best wishes,
Susan.
Susan, in case of that you haven't trimmed your probe (I forgot this when I changed a probe to an another oscilloscope, happens easily).
Hook up the probe to the metal rod at the oscilloscope front saying 1 kHz square wave, adjust the small trimmer capacitor located in the BNC connector of the probe. Ajdust so you'll get a perfect square wave. Judging from the photo you have some losses high up in the frequency, meaning that ringing will be smaller than they are in real life.
Hook up the probe to the metal rod at the oscilloscope front saying 1 kHz square wave, adjust the small trimmer capacitor located in the BNC connector of the probe. Ajdust so you'll get a perfect square wave. Judging from the photo you have some losses high up in the frequency, meaning that ringing will be smaller than they are in real life.
peranders said:
I have adjusted the probes, but unfortunately it looks like the second channel is not 100%. which is why I changed over to putting the main signal on channel 1 (rember this is a 100 MHz bandwidth scope).
"Make do and Mend" is the order of the day.
I am doing the best that I can with what I have...
... of course I could just be having a brunette moment 🙂
Perhaps I should use my HP16500 logic analyzer instead?
Best wishes,
Susan.
Hi Hugo,
Thanks.
I am still running on the bench mostly into an eight (occasionally four) ohm load, with a quick listen on a small bookshelf speaker to check that things are okay.
Once I have all the mods done to my satisfaction I will update my main amps which are currently tucked away under a book shelf in the living room.
They have been working for over eight years without any changes so it will be a bit strange taking a soldering iron to them. I will do a set of tests on them first, and then again after to document the changes.
I still have a number of thing to do first, more transformer tests, etc. before that happens.
Bass seems to be improved, but it is difficult to tell without doing full amp-speaker tests. Then as Eva pointed out one gets into the issues of room reflections.
Best wishes,
Susan.
Netlist said:
Thanks.
I am still running on the bench mostly into an eight (occasionally four) ohm load, with a quick listen on a small bookshelf speaker to check that things are okay.
Once I have all the mods done to my satisfaction I will update my main amps which are currently tucked away under a book shelf in the living room.
They have been working for over eight years without any changes so it will be a bit strange taking a soldering iron to them. I will do a set of tests on them first, and then again after to document the changes.
I still have a number of thing to do first, more transformer tests, etc. before that happens.
Bass seems to be improved, but it is difficult to tell without doing full amp-speaker tests. Then as Eva pointed out one gets into the issues of room reflections.
Best wishes,
Susan.
Hi bobo1on1 ,
Sorry for the delay in answering your question.
My rule of thumb is four times the VA for the peak watts one is going to drive. This is for full range amplifier, if you are running satellite and a separate bass working from another amp the the issue is different.
So 80 VA would be 20 watts - I would probably go for the 2 x 24 volt but the inductance may be a little on the low side.
Do you have any specs for these (what gauge wire is used, and what is the inductance)?
I have a couple of mains toroids somewhere and tomorrow, my cold permitting, I will see if I can find them and make some measurements for you which might help although I think the ones I have are a bit larger.
Best wishes,
Susan.
Sorry for the delay in answering your question.
bobo1on1 said:
My rule of thumb is four times the VA for the peak watts one is going to drive. This is for full range amplifier, if you are running satellite and a separate bass working from another amp the the issue is different.
So 80 VA would be 20 watts - I would probably go for the 2 x 24 volt but the inductance may be a little on the low side.
Do you have any specs for these (what gauge wire is used, and what is the inductance)?
I have a couple of mains toroids somewhere and tomorrow, my cold permitting, I will see if I can find them and make some measurements for you which might help although I think the ones I have are a bit larger.
Best wishes,
Susan.
Re: Re: Respectable Comments
Hi Susan,
Simply 250WRMS using 6 IRFP250N Mosfets and Toroidal transformers for supply and output too, with Filter Capacitance of 60000MFD at 50Volts.
Driver Transformer is also wounded on 50VA toroid due to unavailability of small core.
Biasing with resistor-diode combination , Iq at100mA Per Mosfet
Costruction on Vero board.
So Simple Construct yet so far.
With regards,
Workhorse Technologies.
Susan-Parker said:
Hi Susan,
Simply 250WRMS using 6 IRFP250N Mosfets and Toroidal transformers for supply and output too, with Filter Capacitance of 60000MFD at 50Volts.
Driver Transformer is also wounded on 50VA toroid due to unavailability of small core.
Biasing with resistor-diode combination , Iq at100mA Per Mosfet
Costruction on Vero board.
So Simple Construct yet so far.
With regards,
Workhorse Technologies.
Hi bobo1on1,
I have dug around and unearthed the two closest toroids that I have, unfortunately not very close to the ones you are thinking about:
30 VA, 15 + 15 volts at 1 amp
31.5 mH at 1kHz, 1.2 K ohm
273 mH at 120 Hz, 620 ohm
217 VA, 31 + 31 volts at 3.5 amp
95 mH at 1 kHz, 1.77k ohm
541 mH at 120 Hz, 922 ohm
So reading between the lines, looking to see which way the wind is blowing and checking on the phase of the Moon my answer is:
If you are more interested in hi end response and not so worried about bass, then go for the 2x24 volts.
If you want the bass and are not so worried about the high end then the extra inductance of the 2x35 will help.
It is difficult to make any better judgments as much depends on the inductance, core quality/material, windings, etc.
I hope this helps.
Best wishes,
Susan.
bobo1on1 said:
I have dug around and unearthed the two closest toroids that I have, unfortunately not very close to the ones you are thinking about:
30 VA, 15 + 15 volts at 1 amp
31.5 mH at 1kHz, 1.2 K ohm
273 mH at 120 Hz, 620 ohm
217 VA, 31 + 31 volts at 3.5 amp
95 mH at 1 kHz, 1.77k ohm
541 mH at 120 Hz, 922 ohm
So reading between the lines, looking to see which way the wind is blowing and checking on the phase of the Moon my answer is:
If you are more interested in hi end response and not so worried about bass, then go for the 2x24 volts.
If you want the bass and are not so worried about the high end then the extra inductance of the 2x35 will help.
It is difficult to make any better judgments as much depends on the inductance, core quality/material, windings, etc.
I hope this helps.
Best wishes,
Susan.
Re: Re: Re: Respectable Comments
Hi amp_man_1,
Thank you for the further information.
Sounds like you are making good progress and the power output looks very impressive 🙂
The protection zeners need to be rated at high enough power that they can sink whatever the input transformer is able to drive into them under overdriven conditions.
I am sure you have already taken this into account but I mention this as your 50VA toroid can potentially shovel a lot of current 🙂
Are you winding the toroids yourself?
Any test results?
Best wishes,
Susan.
Hi amp_man_1,
amp_man_1 said:
Thank you for the further information.
Sounds like you are making good progress and the power output looks very impressive 🙂
The protection zeners need to be rated at high enough power that they can sink whatever the input transformer is able to drive into them under overdriven conditions.
I am sure you have already taken this into account but I mention this as your 50VA toroid can potentially shovel a lot of current 🙂
Are you winding the toroids yourself?
Any test results?
Best wishes,
Susan.