Look for asymmetric clipping in high power output at lower frequencies. I had problems with certain songs that had infrasonic bass (circa 20Hz or less). Most music doesn’t go below 40Hz so it’s not a big problem.
That was SE LuFo but Balanced SuSyLu did not have a problem.
That was SE LuFo but Balanced SuSyLu did not have a problem.
I just made a few experiments with the symmetric output stage and my transformers. I could not get the output much higher than about 2 Vrms before it started clipping badly. I tried reversing the polarity of one transformer winding, but no dice. I also made sure the idle currents through both transformer windings were nicely balanced. I am not sure if my problem is with the transformer or something else.
I am still a bit unsure about the polarity of the transformer windings. What would be a simple test to identify the correct / wrong polarity without using the amplifier stage around the transformer?
I am still a bit unsure about the polarity of the transformer windings. What would be a simple test to identify the correct / wrong polarity without using the amplifier stage around the transformer?
Is there a schematic diagram of how the transformer is wired? Be sure that it is not bifilar center tapped. The center tap common would be incorrect polarity.
Put ac signal into one leg and measure with Oscope between legs of secondary to check the phasing.
it needs to be bifilar wound with 4 independent leads.
Check it single ended in LuFo mode first with only one inductor winding and see if it works as 39w amp into 8ohms
Put ac signal into one leg and measure with Oscope between legs of secondary to check the phasing.
it needs to be bifilar wound with 4 independent leads.
Check it single ended in LuFo mode first with only one inductor winding and see if it works as 39w amp into 8ohms
My problem was not with the transformer. I applied the test signal only to one of the transistors, with the other at DC. This upset the power stage. Once I started using balanced drive voltages, things were fine.
Oh good. So it is all playing and making music now? Do you have a photo of the amp test setup? What are you using for balanced signal drive?
You can see a photo of my test setup over in the SuSy T. PuckFo thread. The balanced signal source was my RTX6001 analyser. I also used my test-bench amplifier (Rotel RB980 in bridge mode) to boost the signal higher than the 14 Vpk available from the RTX. I will still have to build a test setup for the front-end part of the amplifier.
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Nice work getting your balanced amp to work! Looks like your inductor is doing what it needs to.
I need to get moving on making my second channel so I can have stereo playing or Mbrennwa is going to beat me to having a stereo set up and running.
You are still mono?
Don't worry, I am still deep in the design phase of SuSy T. PuckFo. It will be a while until I have everything worked out to start building her. There is a lot of chassis work coming up...
Concerning suitable dual-winding inductors for SuSyLu: could a suitable unit be made by taking two identical MOTs, disassembling them and then using the two E cores on opposite sides of a single I core and winding identical coils to put on the center of each E core. The coupling would not be as strong as it would be (I think) with a bifiliar winding on a single coil and core, but there should be some coupling, and more turns with bigger guage wire could generate more mH at a lower DCR. I have a very limited understanding of inductors, so I'd love to hear from more knowledgable folks.
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try a simple EI core PSU transformer
the DC magnetic flux cancels in the SuSYLu it should work
better not to use toroidal
the DC magnetic flux cancels in the SuSYLu it should work
better not to use toroidal
I think Susan Parker demonstrated this with a variant of her Zeus. I think she may have even used a toroidal power transformer. Those would saturate easily with imbalance though.
I had considered taking a MOT apart and adding a winding where the secondary was. It’s real work to wind 14ga magnet wire 100+ times on a tight bobbin.
I had considered taking a MOT apart and adding a winding where the secondary was. It’s real work to wind 14ga magnet wire 100+ times on a tight bobbin.
I’m getting ready to have 600 of the LD1014’s assembled onto the TO247 adapters by a fab house. I can do about a dozen by hand - a man’s got to know his limitations. 🙂 The box of 600 Samtec 3pin SMT headers just came in.
After a 1 year hiatus, I’m going to start the SuSyLu project back up again. Woofertester is helping me with the curve matching. His pro script-automated rig is working well with the TO-247 IMS adapters (mounted upside down here):
Traces from sample LD1014D looks beautiful:
I am ordering the assembly house to start making the 600 TO-247 adapters with LD1014D and 100R mini MELF resistor and Samtec header pin.
Traces from sample LD1014D looks beautiful:
I am ordering the assembly house to start making the 600 TO-247 adapters with LD1014D and 100R mini MELF resistor and Samtec header pin.