While you might think incandescent bulbs are a neat solution for a load, the hot resistance is perhaps 20 times the cold resistance and the thermal time constant is of the order of milliseconds. At what operating point are you expecting to see 15R per bulb?
If there is a problem on the power side, can it go backward and cause a problem at the signal source? I would like to use that circuit for a signal generator.
i posted a few comments that became redundant as I watched the rest of the video, so I deleted them. So here we go... take 3 😅 I like the idea of using incandescent bulbs as a load. I have a heap of trailer bulbs I might wire up for the same purpose. You might be interested in trying bootstrapping to get it to swing better to the rails. Also output parasitic snubbers would be good. One last thing that would be interesting would be to use a fairly high slew rate OP amp and see how well the negative feedback corrects the crossover distortion WITHOUT any bias. You may be surprised since you're using Sziklai pairs which have a base emitter junction voltage of 0.6V or so. The distortion may remain inaudible. I made a bias less 1W amplifier once using an NE5532 once and I couldn't hear it's distortion because of this corrective action of the feedback
Hi APDahlen, Thanks first for the great video. At next i would be interested if you might further explain about biasing and resistor value calculation. That is if somebody wants a different output capabilities (current), voltage gain (R9/R2), different Q1 and Q2. I have not simulated or built this circuit but would be great to do it.
A very useful, well explained video. Thanks for your efforts! I have a very simple question, can you recommend any high power igbt to replace the TIP42 and TIP41 transistors used in the circuit?
hi thank you very much for this great video Sorry for my ignorance but what are the benefits of using a pair of Sziklai pairs instead of a pair of complementary darlington at the output ? moreover have you simulated the circuit ? do you think that simulation SWs can provide results close to reality ?
The Sziklai has less Vbe on voltage as there's only one junction instead of two base emitter junctions in series so it's easier to avoid the cross over distortion.
@@Dazzwidd hi thank you very much for your kind and valuable advice I have looked at some service manuals of vintage preamps and i see that the Sziklai pair was quite popular in the late '70s line preamps are gain stage and buffer stage Today symmetric topologies are more used I wonder why because many still use cap coupling both at input and output There is a competition to design and build the best discrete op amp i.e. with the lowest THD+noise Even if opamps are very tough to beat Kind regards gino
@@gino3286 There's nothing asymmetrical about the Sziklai pair. The symmetry comes from the transformerless push pull output configuration so if you're concerned about symmetry you use a sziklai in the top and bottom half, but you use the compliment sziklai so there's in one an npn/pnp and in the other a pnp/npn. Tell me, have you seen the John Audio Tech channel? It's pretty educational if you want to learn
@@Dazzwidd hi thank you again Yes i understand your advice It is implemented for instance in the old Onkyo P-303 preamp output stage What would be the gain of doubling the single ended circuit ? less distortion ? higher PSRR ? I will look at the channel you mention with great interest I have recently discovered LTSpice Just for curiosity i am trying to simulate some very famous preamps and buffers to see their THD performance at sim I understand that sim is not the reality But it could be useful if used properly Kind regards gino
@@gino3286 So Gino, did you get to see that channel? He covers the Sziklai a bit and there's a fair bit of experimentation and scope analysis. I think you'll be in heaven
While you might think incandescent bulbs are a neat solution for a load, the hot resistance is perhaps 20 times the cold resistance and the thermal time constant is of the order of milliseconds. At what operating point are you expecting to see 15R per bulb?
If there is a problem on the power side, can it go backward and cause a problem at the signal source? I would like to use that circuit for a signal generator.
i posted a few comments that became redundant as I watched the rest of the video, so I deleted them.
So here we go... take 3 😅
I like the idea of using incandescent bulbs as a load. I have a heap of trailer bulbs I might wire up for the same purpose.
You might be interested in trying bootstrapping to get it to swing better to the rails. Also output parasitic snubbers would be good.
One last thing that would be interesting would be to use a fairly high slew rate OP amp and see how well the negative feedback corrects the crossover distortion WITHOUT any bias. You may be surprised since you're using Sziklai pairs which have a base emitter junction voltage of 0.6V or so.
The distortion may remain inaudible.
I made a bias less 1W amplifier once using an NE5532 once and I couldn't hear it's distortion because of this corrective action of the feedback
Great video!
Thank you
Hi APDahlen, Thanks first for the great video. At next i would be interested if you might further explain about biasing and resistor value calculation. That is if somebody wants a different output capabilities (current), voltage gain (R9/R2), different Q1 and Q2. I have not simulated or built this circuit but would be great to do it.
Thank you for the video😊
Does this amplify (amps) or just voltage
A very useful, well explained video. Thanks for your efforts! I have a very simple question, can you recommend any high power igbt to replace the TIP42 and TIP41 transistors used in the circuit?
hi thank you very much for this great video Sorry for my ignorance but what are the benefits of using a pair of Sziklai pairs instead of a pair of complementary darlington at the output ?
moreover have you simulated the circuit ? do you think that simulation SWs can provide results close to reality ?
The Sziklai has less Vbe on voltage as there's only one junction instead of two base emitter junctions in series so it's easier to avoid the cross over distortion.
@@Dazzwidd hi thank you very much for your kind and valuable advice
I have looked at some service manuals of vintage preamps and i see that the Sziklai pair was quite popular in the late '70s line preamps are gain stage and buffer stage
Today symmetric topologies are more used
I wonder why because many still use cap coupling both at input and output
There is a competition to design and build the best discrete op amp i.e. with the lowest THD+noise
Even if opamps are very tough to beat
Kind regards gino
@@gino3286 There's nothing asymmetrical about the Sziklai pair. The symmetry comes from the transformerless push pull output configuration so if you're concerned about symmetry you use a sziklai in the top and bottom half, but you use the compliment sziklai so there's in one an npn/pnp and in the other a pnp/npn. Tell me, have you seen the John Audio Tech channel? It's pretty educational if you want to learn
@@Dazzwidd hi thank you again
Yes i understand your advice It is implemented for instance in the old Onkyo P-303 preamp output stage
What would be the gain of doubling the single ended circuit ? less distortion ? higher PSRR ?
I will look at the channel you mention with great interest
I have recently discovered LTSpice Just for curiosity i am trying to simulate some very famous preamps and buffers to see their THD performance at sim
I understand that sim is not the reality
But it could be useful if used properly
Kind regards gino
@@gino3286 So Gino, did you get to see that channel? He covers the Sziklai a bit and there's a fair bit of experimentation and scope analysis. I think you'll be in heaven