Hello,
I'm a tube guy, but with limits. I have built gainclones and discrete amps that sound really nice, but tubes offer me a warmt that I like. The reason is the opt transformer, the output transformer is a funky device becouse it puts a colour on the sound that I have yet to make with bandpass, low pass and all other kind of filters that I have tried. Nor do this happend with a input transformer. So her is the question, does any one know were to get op transformers for transistor circuits? And that must be hifi, not the very small dirt used in portable radios and a little powerfull(1-15w). I guess I need a load of 200-500ohm.
Best regards,
Magnus Kofoed
I'm a tube guy, but with limits. I have built gainclones and discrete amps that sound really nice, but tubes offer me a warmt that I like. The reason is the opt transformer, the output transformer is a funky device becouse it puts a colour on the sound that I have yet to make with bandpass, low pass and all other kind of filters that I have tried. Nor do this happend with a input transformer. So her is the question, does any one know were to get op transformers for transistor circuits? And that must be hifi, not the very small dirt used in portable radios and a little powerfull(1-15w). I guess I need a load of 200-500ohm.
Best regards,
Magnus Kofoed
Hi,
well, my experience says that it is the opt that has most with the warmt of the sound to do. I don't say that will sound like a tube amp with transistors and opt. But for me I think a transistor amp with opt will sound better, I guess it's a taste thing. Tube pre amp sound better than transistors, yes, I think so, but they lack some of the warmt, a tube pre will improve the sound quality of transistor power stage, but still, no warm sound. I respect they who don't agree. This is not ment to be a tube vs transistor thread.
A opt may degrade the whole sound quality, but for me it sounds most right. Again, a taste thing.
But, I might be completly wrong, thats why I want to get some transformer to test.
Ill guess I'm crazy...
Best regards,
Magnus
well, my experience says that it is the opt that has most with the warmt of the sound to do. I don't say that will sound like a tube amp with transistors and opt. But for me I think a transistor amp with opt will sound better, I guess it's a taste thing. Tube pre amp sound better than transistors, yes, I think so, but they lack some of the warmt, a tube pre will improve the sound quality of transistor power stage, but still, no warm sound. I respect they who don't agree. This is not ment to be a tube vs transistor thread.
A opt may degrade the whole sound quality, but for me it sounds most right. Again, a taste thing.
But, I might be completly wrong, thats why I want to get some transformer to test.
Ill guess I'm crazy...
Best regards,
Magnus
Maybe this thread by Susan-Parker may interest you:
Zero Feedback Impedance Amplifier
Cheers Michael
Zero Feedback Impedance Amplifier
Cheers Michael
First of all, all transformers are natural low-pass filters. This could be one of the many reasons that characterize OPT amps.
Second, an output transformer is a current-driven-current-source, which behaves very differently from normal voltage-driven-voltage-source solid state amplifiers. According to physics, force applied to coils is linear to the current through the coil, not the voltage applied across the coil. Controlling the voltage accross the coil to be linear does not make the motion of cone linear if the impedance varies with time or frequency.
This could explain why fullrange driver speakers usually doesn't sound as good when driven by an OTL.
Second, an output transformer is a current-driven-current-source, which behaves very differently from normal voltage-driven-voltage-source solid state amplifiers. According to physics, force applied to coils is linear to the current through the coil, not the voltage applied across the coil. Controlling the voltage accross the coil to be linear does not make the motion of cone linear if the impedance varies with time or frequency.
This could explain why fullrange driver speakers usually doesn't sound as good when driven by an OTL.
Hi, Magnus.
You are not crazy. Transformer coupled amplifiers sounds better
than regular SS amplifier.
But this is because of topology similar to tube amplifiers.
If you just connect transformer to the output of SS amplifier you degrade the sound.
Hi, EJ.
Susan Parker and my amplifiers are normal voltage source amplifiers with output impedance of push-pull souce follower/n^2.
(n=Turns Ratio Np/Ns).
You are not crazy. Transformer coupled amplifiers sounds better
than regular SS amplifier.
But this is because of topology similar to tube amplifiers.
If you just connect transformer to the output of SS amplifier you degrade the sound.
Hi, EJ.
Susan Parker and my amplifiers are normal voltage source amplifiers with output impedance of push-pull souce follower/n^2.
(n=Turns Ratio Np/Ns).
Hi Rozak,
All transformers are current controlled current source. The windings are coupled by magnetic fields (flux, to be precise), and magnatic fields are generated by current, NOT VOLTAGE. The only relation between input winding and output winding is I1*N1=I2*N2 (except when saturated). Voltage is just a result of current flowing through the resistor (or whatsoever) and doesn't matter. Only Current matters. This is the physical nature and has nothing to do with circuit topology.
The circuit before the tranformer is a voltage amplifier. The voltage output generates current through the primary windings of the OPT, and the OPT controls the current through the secondary winding by magnetic field coupling. It controls ONLY the current. It doesn't control the voltage. That's why I said it's a CCCS.
All transformers are current controlled current source. The windings are coupled by magnetic fields (flux, to be precise), and magnatic fields are generated by current, NOT VOLTAGE. The only relation between input winding and output winding is I1*N1=I2*N2 (except when saturated). Voltage is just a result of current flowing through the resistor (or whatsoever) and doesn't matter. Only Current matters. This is the physical nature and has nothing to do with circuit topology.
The circuit before the tranformer is a voltage amplifier. The voltage output generates current through the primary windings of the OPT, and the OPT controls the current through the secondary winding by magnetic field coupling. It controls ONLY the current. It doesn't control the voltage. That's why I said it's a CCCS.
Hi guys,
This i really intresting stuff.
Yes, I understand that if I hook up a transformer directly to the output of a ss amp, it will degrade it's sound, that was not my plan. My plan was to design something like susan amp.
lndm,
You may got a point about the resistors, but I don't belivie in degradeing the resistors to carbon film. I always use metal film. Personal, I don't belive that resistors make the sound, they make the noise!
Thanks for all the info and keep it coming.
Best regards,
Magnus
This i really intresting stuff.
Yes, I understand that if I hook up a transformer directly to the output of a ss amp, it will degrade it's sound, that was not my plan. My plan was to design something like susan amp.
lndm,
You may got a point about the resistors, but I don't belivie in degradeing the resistors to carbon film. I always use metal film. Personal, I don't belive that resistors make the sound, they make the noise!
Thanks for all the info and keep it coming.
Best regards,
Magnus
Owning transformer coupled SS amps driven with both styles of output stages, I must say I do not agree that the Parker style sounds better.
The power bandwidth of the output transformer in question is 10hz~100Khz, and it sounds better than 99.9% of the direct coupled SS amps on the market today. It might even sound better without the transformer, but I will never know. As is, it can deliver full power at any impedance from 2 ohms to 16 ohms.
YMMV
The power bandwidth of the output transformer in question is 10hz~100Khz, and it sounds better than 99.9% of the direct coupled SS amps on the market today. It might even sound better without the transformer, but I will never know. As is, it can deliver full power at any impedance from 2 ohms to 16 ohms.
YMMV
Makofoed-6sn7 said:
I don't think carbon resistors are noisy. Well for a first phono stage yes, but this is completely inaudible for a crossover and a power amp. Besides, carbon resistors typically have superior surge performance, and are chosen for RF work due to their low inductance.
BTW, I feel that some generic metal films can sound harsh, and many mf's are a little bright (in a good way at least).
"Very interestingly. Can you please tell more about your amps and
second style."
I think it may be more a matter of execution more than anything.
I have at least nine transformer coupled SS amps at home right now, I own all but two of them (I'm supposed to be repairing/modifying these).
The worst sounding ones are the models with the B+ on the center tap of the output transformer.
The ones with an output coupling cap driving the output transformer sound better.
The ones with outputs driven from ±V supplies direct coupled to the output transformer sound the best.
The best sounding one has a complementary CFP triple output stage with a voltage gain of five directly coupled to a multi-filar autoformer. The front end is a diff pair with a resistive current source, and a VAS with a resistive current source (three transistors total). The front end has a regulated supply.
The McIntosh output iron sounds the best. I also have iron from Altec, Bozak, Dukane, McMartin, and Pyramid.
The modifications are mainly capacitors, it makes a huge difference.
second style."
I think it may be more a matter of execution more than anything.
I have at least nine transformer coupled SS amps at home right now, I own all but two of them (I'm supposed to be repairing/modifying these).
The worst sounding ones are the models with the B+ on the center tap of the output transformer.
The ones with an output coupling cap driving the output transformer sound better.
The ones with outputs driven from ±V supplies direct coupled to the output transformer sound the best.
The best sounding one has a complementary CFP triple output stage with a voltage gain of five directly coupled to a multi-filar autoformer. The front end is a diff pair with a resistive current source, and a VAS with a resistive current source (three transistors total). The front end has a regulated supply.
The McIntosh output iron sounds the best. I also have iron from Altec, Bozak, Dukane, McMartin, and Pyramid.
The modifications are mainly capacitors, it makes a huge difference.
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