I bought a box of mystery SE transformers once. If I remember correctly, You can get a decent reading on them with an LCR meter on the primary and using the wanted load on the secondary. I think i was measuring resistance at 1kHz on the primary with a 4ohm resistor on the secondary. doesn't really give you an indication of how much current it can take though. thanks for the videos Aaron.
I wonder if there is any way to high pass filter the output before it goes through the output transformer, to get rid of the DC current? But whatever that high pass filter would be made of would of course need to handle quite a lot of power...
Of course, you could use another transformer to remove the DC component first, but then that transformer would probably need an air gap. (And you would need second transformer...) Or if you had a transformer with 3 windings then you could run a reverse current in the third winding to cancel the magnetic field from the DC current in the primary winding. But then you would need a current source for that, and it would probably consume a lot of extra power too... Maybe if you used the current from the output tube again, but this time bypassed the 3rd transformer winding with a capacitor to only get the DC current through the winding. But then you would probably need a pretty big power capacitor...
Once i build a output module for my modular synthesizer and i used a German Neutrik NTE10/3 transformer. it was a bit of guessing, but it work perfectly.
I watched a few videos from this class and really enjoyed it. One thing I always struggeled with is chosing a OT for a Single-Ended or Push-Pull amp. I always choose the primary impedance based on similar amps that have been around like 3k2 for any 2*EL34 Push-Pull amp (like 50 Watt Marshalls ). Any chance you could include it in a future video. I'd love to finally be able to make a choice based on actual numbers instead of copying from old designs.
This series is so comprehensive, it actually helped me understand tube amps. I’m currently in the process of learning design criteria and there’s only one thing I’m not finding anywhere, namely how to determine the turns ratio given a speaker and a tube already biased, the Thévenin equivalent circuit looking down in the tube is what helps calculate the impedance I have to match with the transformer?
man every time I wake up in the middle of the night to sneak a snack, theres a new video of this awesome shtuff for me to watch while I shove leftovers in my face.
How can you tell there is an "Air Gap" for single ended amplifiers output transformers? The Air Gap just passes the high Plate DC voltage or does the Air Gap in the output transformers does something else?
@@Lantertronics I will have to research about it because I never heard of Air Gap Transformers being used in guitar amplifiers for single end Class A guitar amplifiers. The output transformers all look the same to be can't tell if there is an Air Gap internally
@@Lantertronics Most fender and marshall uses their own part numbers because they get them from a certain factory, Even the old fender amps 50's part numbers are fenders part numbers for their own BOM bill of materials. VOX amplifiers in the 60's I think is the same with the part numbers being a VOX part number.
Howdy. In a PP amp the induction may be designed to reach about 1,1 Tesla both ways. In a SE amp the DC may not cause the induction to be more than about half that, say 0,5 Tesla. This reduction can be achieved using an air gap. Now the induction can be rated to a swing of 0,5 T + - 0,5 T or 0 - 1 Tesla. The design math of air gap magnetics is complicated though. Regards.
5:40 “In the last lecture we calculated a plate current of 37mA? Close enough”
Output transformer saturation is a wonderful sound.
I bought a box of mystery SE transformers once.
If I remember correctly, You can get a decent reading on them with an LCR meter on the primary and using the wanted load on the secondary.
I think i was measuring resistance at 1kHz on the primary with a 4ohm resistor on the secondary.
doesn't really give you an indication of how much current it can take though.
thanks for the videos Aaron.
Very succinct. TIL that an output xformer for a single-ended amp needs an air gap.
Thanks!
I wonder if there is any way to high pass filter the output before it goes through the output transformer, to get rid of the DC current? But whatever that high pass filter would be made of would of course need to handle quite a lot of power...
Of course, you could use another transformer to remove the DC component first, but then that transformer would probably need an air gap. (And you would need second transformer...)
Or if you had a transformer with 3 windings then you could run a reverse current in the third winding to cancel the magnetic field from the DC current in the primary winding. But then you would need a current source for that, and it would probably consume a lot of extra power too... Maybe if you used the current from the output tube again, but this time bypassed the 3rd transformer winding with a capacitor to only get the DC current through the winding. But then you would probably need a pretty big power capacitor...
Once i build a output module for my modular synthesizer and i used a German Neutrik NTE10/3 transformer.
it was a bit of guessing, but it work perfectly.
Also the impedance ratio is calculated at 1 Khz usually.
I watched a few videos from this class and really enjoyed it. One thing I always struggeled with is chosing a OT for a Single-Ended or Push-Pull amp. I always choose the primary impedance based on similar amps that have been around like 3k2 for any 2*EL34 Push-Pull amp (like 50 Watt Marshalls ). Any chance you could include it in a future video. I'd love to finally be able to make a choice based on actual numbers instead of copying from old designs.
The very next lecture will get into some of that -- basically the reflected impedance will define what the AC load line is.
This series is so comprehensive, it actually helped me understand tube amps. I’m currently in the process of learning design criteria and there’s only one thing I’m not finding anywhere, namely how to determine the turns ratio given a speaker and a tube already biased, the Thévenin equivalent circuit looking down in the tube is what helps calculate the impedance I have to match with the transformer?
Excellent
Thanks!
man every time I wake up in the middle of the night to sneak a snack, theres a new video of this awesome shtuff for me to watch while I shove leftovers in my face.
How can you tell there is an "Air Gap" for single ended amplifiers output transformers? The Air Gap just passes the high Plate DC voltage or does the Air Gap in the output transformers does something else?
Google "air gap transformer" without the quotes, there are some nice write-ups out there.
@@Lantertronics I will have to research about it because I never heard of Air Gap Transformers being used in guitar amplifiers for single end Class A guitar amplifiers. The output transformers all look the same to be can't tell if there is an Air Gap internally
@@waynegram8907 You'd probably need to look up the part number.
@@Lantertronics Most fender and marshall uses their own part numbers because they get them from a certain factory, Even the old fender amps 50's part numbers are fenders part numbers for their own BOM bill of materials. VOX amplifiers in the 60's I think is the same with the part numbers being a VOX part number.
Howdy.
In a PP amp the induction may be designed to reach about 1,1 Tesla both ways.
In a SE amp the DC may not cause the induction to be more than about half that, say 0,5 Tesla. This reduction can be achieved using an air gap. Now the induction can be rated to a swing of 0,5 T + - 0,5 T or 0 - 1 Tesla.
The design math of air gap magnetics is complicated though.
Regards.