Hi all,
I ran out of ideas, particularly after blowing another pair of F5A fuses.
Tried various combinations of compensation, but the only one that is stable with my physical layout is Cdom set to 94pF.
I have now tried listening to the amp again with Cdom set to 74pF knowing that it peaks up the 10kHz square wave into a resistor load and shows mild ripple into R//C loads.
This under compensated version has a touch more treble but is to be expected into a reactive speaker. I don't notice any exaggeration of sibilance. Still not what I expect though.
Bass is starting to get to me. I would need to rebalance the Q of this speaker to suit the wideband signal.
I am going to start the second but with a slightly different physical layout and then compare the two.
I will have to DC block the input, my pre-amp sends various offsets depending on on/off, mute/play.
I ran out of ideas, particularly after blowing another pair of F5A fuses.
Tried various combinations of compensation, but the only one that is stable with my physical layout is Cdom set to 94pF.
I have now tried listening to the amp again with Cdom set to 74pF knowing that it peaks up the 10kHz square wave into a resistor load and shows mild ripple into R//C loads.
This under compensated version has a touch more treble but is to be expected into a reactive speaker. I don't notice any exaggeration of sibilance. Still not what I expect though.
Bass is starting to get to me. I would need to rebalance the Q of this speaker to suit the wideband signal.
I am going to start the second but with a slightly different physical layout and then compare the two.
I will have to DC block the input, my pre-amp sends various offsets depending on on/off, mute/play.
Harry3
I dont have a working 100 clone yet - I am still struggling to finish the basic heatsink metalwork for the 50/100 clone monoblocks. The first 50 clone sounded nice but did not have the wow factor of the commercial 50.2. Pierre Watts measured the commercial 50.2 voltages and it now appears as if most of us have been using a too low voltage in our amps. Until I upgrade the clone PSU to the same voltages of the commercial 50.2 the answer remains uncertain.
I am not discounting the 50 clone project. My plan is to include a Pinkmouse 50 clone (what a mystery that name still remains!!) in the 100 clone box, but this time keeping more strictly to the commercial 50.2 PSU specifications.
For the moment I prefer the commercial 50.2 amp to all my other amps. Once fully warmed up the 3 dimensional soundstage this amp can project on a good recording is simply incredible. I have not yet head a class B or D amp that can do it.
I am about to rewire my commercial 100.2 output stage with thicker Van den Hull wire and hopefully the amp will then outperform the commercial 50.2 as suggested in the original 100.2 reviews.
So for the moment, the commercial 50.2 wins hand down when it comes to overall listening pleasure. If it was'nt for the fact that my car was recently stolen I would most likely have started scouting for a second 50.2....
Jozua
I dont have a working 100 clone yet - I am still struggling to finish the basic heatsink metalwork for the 50/100 clone monoblocks. The first 50 clone sounded nice but did not have the wow factor of the commercial 50.2. Pierre Watts measured the commercial 50.2 voltages and it now appears as if most of us have been using a too low voltage in our amps. Until I upgrade the clone PSU to the same voltages of the commercial 50.2 the answer remains uncertain.
I am not discounting the 50 clone project. My plan is to include a Pinkmouse 50 clone (what a mystery that name still remains!!) in the 100 clone box, but this time keeping more strictly to the commercial 50.2 PSU specifications.
For the moment I prefer the commercial 50.2 amp to all my other amps. Once fully warmed up the 3 dimensional soundstage this amp can project on a good recording is simply incredible. I have not yet head a class B or D amp that can do it.
I am about to rewire my commercial 100.2 output stage with thicker Van den Hull wire and hopefully the amp will then outperform the commercial 50.2 as suggested in the original 100.2 reviews.
So for the moment, the commercial 50.2 wins hand down when it comes to overall listening pleasure. If it was'nt for the fact that my car was recently stolen I would most likely have started scouting for a second 50.2....
Jozua
Loek
Here is the link:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=31077&perpage=10&pagenumber=736
Note the significant higher PSU voltages compared to the original clone specs.
Regards
Jozua
Here is the link:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=31077&perpage=10&pagenumber=736
Note the significant higher PSU voltages compared to the original clone specs.
Regards
Jozua
Hey guys... check out this tranny and let me know what you all think.
It has 2- 40 volt secondaries and that should give around 54 volts DC, I use 1.36 times the AC voltage... seems to hold much more to real life. To me its a bit of overkill size wise but what the heck, its priced reasonable for its size.... Price 148.00 each and there are two extra 12 volt windings to operate protection relays and such.
Check out the AN-15440 toroid here.....
http://www.toroid-transformer.com/
Mark
It has 2- 40 volt secondaries and that should give around 54 volts DC, I use 1.36 times the AC voltage... seems to hold much more to real life. To me its a bit of overkill size wise but what the heck, its priced reasonable for its size.... Price 148.00 each and there are two extra 12 volt windings to operate protection relays and such.
Check out the AN-15440 toroid here.....
http://www.toroid-transformer.com/
Mark
I have been very happy with John's transformers, and the service is excellent. Sure for the most part you get what you pay for, but they are a good and so far reliable transformer, at least in the sizes I have bought (500VA down). Construction quality seems good, wire size is generous. The rubber washer smells really bad for a few days though....This is the same guy selling enclosures at www.par-metal.com
Jozua said:
Hi Jozua,
thanks for the reply. When you get some time, it would be interesting to know if the 50Watt clones that we have use the same circuit as your commercial 50.2.
As for the stolen car, you and Pierre should be thinking of moving to Australia. You're probably the only two that haven't
Harry3
I might just do that!! Especially, as I dont know what is next.
Two weeks ago I arrive home only to find that the copper waterpypes of my house had been ripped out of the wall and the backyard under water. That copper was most likely sold as srap for $5.00 compared to my damages which involves having the wall chopped open in order to re-connect some pypes.
It is very frustrating as this is the 3rd time that I have been a victim of crime in 18 months.
People who live in countries where they dont have to lock their doors should appreciate what they have.
I just wondering is audio as good in Australia...as it is in South Africa....?
Jozua
I might just do that!! Especially, as I dont know what is next.
Two weeks ago I arrive home only to find that the copper waterpypes of my house had been ripped out of the wall and the backyard under water. That copper was most likely sold as srap for $5.00 compared to my damages which involves having the wall chopped open in order to re-connect some pypes.
It is very frustrating as this is the 3rd time that I have been a victim of crime in 18 months.
People who live in countries where they dont have to lock their doors should appreciate what they have.
I just wondering is audio as good in Australia...as it is in South Africa....?
Jozua
Mark A. Gulbrandsen said:
If, I can get my computer to download from the camera.Mark A. Gulbrandsen said:
The school computer manages to download but I can't do anything with them. But, it did confirm that my focussing technique using this silly LCD screen (both viewfinder and back of camera) needs to be completely different from that which I use with my analogue cameras.
AndrewT said:
Andrew, do you use isolated heat sinks because you have mount the transistors without any transistor-pads in between or for some other reason?
Normally, the chassis (consisting of one or more heat sinks, front and rear panels, top and bottom) form an EMC secure and totally grounded box. This arrangement prevent the sophisticated electronics (inside) to interact internally and to the EMC surroundings. Also it prevent the power-stage from being unstable and starting undesired oscillations. (big heat sinks act like big capacitors if not grounded)
. Note, big heat sink, if anodized you had to remove the anodized surface at the grounding point to be sure you have good grounding connection. Normally this is not an issue if the mounting holes (drilled and threaded) was made after the anodizing was done (anodized aluminum is a very good and hard to brake through, electrical isolator . You could also place some capacitors in between the power transistor rails and ground (0V at the power caps.), but not needed if good square waves is to be visible at your oscilloscope (≤ 20kHz).
But, I guess you already know all this
.Regards
Hi Flod,
I have seen past references to the occasional need for EF collector to ground bypass caps to avoid instability in the amp.
I normally test my amps with a separated transformer and with the heatsink lying bare on the bench, with the amp output stage bolted to it. The sink is electrically isolated from the output stage in the EFs I usually use.
All my previous outputs have never exceeded 3pairs and the heatsink never exceeded 0.03sq m back plate area (<48sq in).
This has never caused a problem in the past.
During final assembly the heatsink is bolted into the chassis and thus is automatically connected to safety earth. Again I have rarely seen a problem done this way. Thinking back, I did have a VFET pair of amps that persisted in blowing up, I wonder if the safety earth was part of the problem. I gave up with them after about 3months of wasted effort re-re-building (I will not divulge the make).
However, this time I am using 6pair on 0.16sq m of heatsink backplate. I have to reassemble after yet another experiment that failed to remove the square wave peaking into a resistor load and mild oscillation into a reactive load. Damn I blew yet another pair of fuses, carelessly connected PCB out to audio ground when I should have connected it to output line, I hope the drivers are OK.
Will try re-wiring this afternoon and test tomorrow.
Should I connect the three sinks to audio ground?
I see no point in connecting them to safety earth since the whole amp is isolated from the mains.
I have seen past references to the occasional need for EF collector to ground bypass caps to avoid instability in the amp.
I normally test my amps with a separated transformer and with the heatsink lying bare on the bench, with the amp output stage bolted to it. The sink is electrically isolated from the output stage in the EFs I usually use.
All my previous outputs have never exceeded 3pairs and the heatsink never exceeded 0.03sq m back plate area (<48sq in).
This has never caused a problem in the past.
During final assembly the heatsink is bolted into the chassis and thus is automatically connected to safety earth. Again I have rarely seen a problem done this way. Thinking back, I did have a VFET pair of amps that persisted in blowing up, I wonder if the safety earth was part of the problem. I gave up with them after about 3months of wasted effort re-re-building (I will not divulge the make).
However, this time I am using 6pair on 0.16sq m of heatsink backplate. I have to reassemble after yet another experiment that failed to remove the square wave peaking into a resistor load and mild oscillation into a reactive load. Damn I blew yet another pair of fuses, carelessly connected PCB out to audio ground when I should have connected it to output line, I hope the drivers are OK.
Will try re-wiring this afternoon and test tomorrow.
Should I connect the three sinks to audio ground?
I see no point in connecting them to safety earth since the whole amp is isolated from the mains.
Hi Andrew.
I should have wired each heat sinks earth/ground (body) to power caps 0V, e.g. a star connections (which also is the audio 0V/ ground) for to prevent any ground loops. This should only be done if you hasnt bolted all sinks together by a type of chassis, otherwise you could get ground loops. All power rails (pos and neg) wires should be as short as possible. Especially the return wires/cables.
Sometimes you also had to compensate the measuring cable to the oscilloscope if measuring square waves, for to prevent ringings and other unwanted oscillations in the measuring cable. Safety earth could also be a problem. Check for if it should be connected to amp (measure).
Regards
I should have wired each heat sinks earth/ground (body) to power caps 0V, e.g. a star connections (which also is the audio 0V/ ground) for to prevent any ground loops. This should only be done if you hasnt bolted all sinks together by a type of chassis, otherwise you could get ground loops. All power rails (pos and neg) wires should be as short as possible. Especially the return wires/cables.
Sometimes you also had to compensate the measuring cable to the oscilloscope if measuring square waves, for to prevent ringings and other unwanted oscillations in the measuring cable. Safety earth could also be a problem. Check for if it should be connected to amp (measure).
Regards