Nimam mica navadne mam keramicne.
Ti mogoce ves kaj je to za en problem,ki me ze posteno zivcira.
Saj razumes angleski,vse pise zgoraj.
Ti mogoce ves kaj je to za en problem,ki me ze posteno zivcira.
Saj razumes angleski,vse pise zgoraj.
I dont know what was said in the above 2 posts (please post in ENGLISH!) but i will say this... until you get a suitable transformer, you will continue to have severe problems and it's only a matter of time before you start blowing components all over the place.
"I can't hear you. Are you using a scrambler?"
"Sorry, I can't hear you. I'm using a scrambler."
Jocko
"Sorry, I can't hear you. I'm using a scrambler."
Jocko
Wow, no center tapped transformer..... so the system ground is floating entirely and held entirely with the storage caps. What happens after some time is the ground eventually floats up toward one of the rails and the you end up with twice your rail voltage on one side, and nothing on the other (which would produce highly unpredictable results if not magic smoke or explosion of the filter caps)
Some Hafler amplifiers use floating (non center tapped) power supplies but this method doesnt work without special topology to shift the supply from rail to rail.
I bet if you can bridge the amp it might work a little better.
Some Hafler amplifiers use floating (non center tapped) power supplies but this method doesnt work without special topology to shift the supply from rail to rail.
I bet if you can bridge the amp it might work a little better.
AudioFreak said:
Solution,and now realy final
Center tap was the problem and i change transformer(some old one with two secondary windings-2x18V)and now all works fine.
Sure when i got transformer i was a little confused,but this is my first tranzistor amp and just putting circuits boards together first time with no errors was great success(many have failed).
So then i have you all good guys to help me solve problems.
P.S.Amp didnt blow up or even blow tranzistors.Amp just shuts down after 1hour of listening.I mailed also author imself prof.Leach and he gave me same advice.At least i got transformer cheap 55EURO.Now i get myself new one,more power added:500VA 🙂
Center tap was the problem and i change transformer(some old one with two secondary windings-2x18V)and now all works fine.
Sure when i got transformer i was a little confused,but this is my first tranzistor amp and just putting circuits boards together first time with no errors was great success(many have failed).
So then i have you all good guys to help me solve problems.
P.S.Amp didnt blow up or even blow tranzistors.Amp just shuts down after 1hour of listening.I mailed also author imself prof.Leach and he gave me same advice.At least i got transformer cheap 55EURO.Now i get myself new one,more power added:500VA 🙂
Tell me, what transformer do you got? I got toroid from IET Tovornik, with 2×42 secondaries and 300VA for one channel. I connect the middle taps together and connect it to ground point. All wires meet at this point and one wire goes to ground connection of electrical socket.
I connect both channels at this point and without any problem. I think the problem is with transformer, because if you do not have central tapped wire connect to ground you will get floating voltage.
Do you have connect the central point to the electrical groung in your socket (ozemljitev)?
Bye, supernet!
I connect both channels at this point and without any problem. I think the problem is with transformer, because if you do not have central tapped wire connect to ground you will get floating voltage.
Do you have connect the central point to the electrical groung in your socket (ozemljitev)?
Bye, supernet!
Supernet i have toroid form HIT Elektronik and it is 40V secondary.
R. McAnally is right you probaly have just one 42V secondary 2x is too much.Do you have 4 wires on output?Then you have probaly 2x21V(together 42V total) that is transformer i'm buying now.I only increase power to 500VA from 400VA you probaly shoud too cause 300W is a little bit low.HIT Elektronik is the cheapest olny 6000 SIT for 500VA.
My not working transformer have only 2 wires on secondary and that is wrong (my mistake while ordering)
R. McAnally is right you probaly have just one 42V secondary 2x is too much.Do you have 4 wires on output?Then you have probaly 2x21V(together 42V total) that is transformer i'm buying now.I only increase power to 500VA from 400VA you probaly shoud too cause 300W is a little bit low.HIT Elektronik is the cheapest olny 6000 SIT for 500VA.
My not working transformer have only 2 wires on secondary and that is wrong (my mistake while ordering)
R Mc Annaly said :
"Some Hafler amplifiers use floating (non center tapped) power supplies but this method doesnt work without special topology to shift the supply from rail to rail. "
I' ve seen other schematics using a non-center-tapped transformer, from Revox (tape recorder fame...), and from QUAD (model 306), they generate a signal ground using low value resistors or a class B push-pull low power amplifier,the feedback and signal are referenced to this GND, and the equivalent schematic would put the supply bypass caps in series with the load to the mid point of the power supply( hopefully same voltage as the signal ground...)
The wiring arrangement is probably very important with such a trick...
😉
"Some Hafler amplifiers use floating (non center tapped) power supplies but this method doesnt work without special topology to shift the supply from rail to rail. "
I' ve seen other schematics using a non-center-tapped transformer, from Revox (tape recorder fame...), and from QUAD (model 306), they generate a signal ground using low value resistors or a class B push-pull low power amplifier,the feedback and signal are referenced to this GND, and the equivalent schematic would put the supply bypass caps in series with the load to the mid point of the power supply( hopefully same voltage as the signal ground...)
The wiring arrangement is probably very important with such a trick...
😉
I dont know any of these amps,but i'm waiting now for new transformer and all turned just nice 😀
vbd said:
It is possible to use non center tapped transformers in low power applications such as outputs of pre-amps. You arecorrect "Virtual" grounds are made using resistors or op-amp followers as you noted.
In high power applications requiring direct coupled single ended outputs, it is possible to "float" a single ended power supply between each rail depending on whether the signal is in the positive or negative part of the cycle. It is done mostly in class D applications and nearly all BD designs by Hafler and Rockford. This is very interesting because only half the supply voltage is needed (one +V voltage instead of +-V) and regulation of each rail seperatly is no longer required since the same voltage is used for both rails alternatly.
I sidetracked a little but it's a damn good idea. 😀
Sorry Shadow, but you will need a transformer with 2×42V or 2×40V this means you will need 4 WIRES!!!! from transformer. The middle two go tapped together and connected to ground.
You can not use just one winding, because you need +/- 58 Volts not + 58V.
And by the way 2×21V is to low for amp, because you will drive them into clipping. I RECOMMEND AT LEAST 2×40VOLTS. My amp uses one 300VA toroid per channel with 4×4700microF caps and it sounds pretty hefty.
Supernet.
You can not use just one winding, because you need +/- 58 Volts not + 58V.
And by the way 2×21V is to low for amp, because you will drive them into clipping. I RECOMMEND AT LEAST 2×40VOLTS. My amp uses one 300VA toroid per channel with 4×4700microF caps and it sounds pretty hefty.
Supernet.
Supernet i dont know what kind of transformer you have,but my type will give you 2x42V sekundary that is 2x41=82Vsec.So peak +/- voltage will be(sine wave) 82Vx1.4142=116V?!
I have now older Conrad transformer and he have 2x18V sec that is 52.5V,transformer have truly 4 secondary wires + 2 primar
My amp uses in total 6x10.000 uF caps.
You probaly missunderstood something.
I have now older Conrad transformer and he have 2x18V sec that is 52.5V,transformer have truly 4 secondary wires + 2 primar
My amp uses in total 6x10.000 uF caps.
You probaly missunderstood something.
Yep, given that the leach is a Class AB design, recified voltage will probably be around 1.4 x Vac so 2 x 42Vac secondaries will give rails of almost +/- 60V which would seems very high but according to Professor Leach, this is correct :S anyway..... just my 2cents.
yep.... 2 secondary windings ... one for +ve rail and one for -ve rail .... +/-58Vdc total which is what professor leach says to use.
2 x 42Vac secondaries will render a supply of around +/-60V which is what i stated in my earlier post. Supernet is using a suitable transformer for this application...
2 x 42Vac secondaries will render a supply of around +/-60V which is what i stated in my earlier post. Supernet is using a suitable transformer for this application...
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