Yes 600:15k can be used as 15k:600. In parafeed config the tranny need not to have air-gap since no dc is present. But the tranny as presented here will not drive your 50R HP if connected across pin 1 and 4. Please ask your shop owner what is the impedance between pin 1 and 2 and/or pin 1 and 3.
I have a humble request to you. The questions you are asking are no issues in the context of 3A5 as the driving DHT but the HT supply, LT supply, proper and well thought out grounding and very careful layout is. Said that go for a 15K:50R parafeed tranny and concentrate on the real issues.
Regards
I have a humble request to you. The questions you are asking are no issues in the context of 3A5 as the driving DHT but the HT supply, LT supply, proper and well thought out grounding and very careful layout is. Said that go for a 15K:50R parafeed tranny and concentrate on the real issues.
Regards
15K:600 isn't going to work well for most headphones.
EDCOR - XSM Series
The 10K:150 is about the closest to ideal that I can find, and these aren't all that expensive.
EDCOR - XSM Series
The 10K:150 is about the closest to ideal that I can find, and these aren't all that expensive.
Why? As the datasheet says, there's only a need for one resistor across the half next to the negative end to compensate for the plate current of the other triode that is also flowing through this filament part.
Best regards!
Hammond 156C. (Another part of the reason I went with higher voltage and lower current for the schematic I drew for you)
supernut,
You need to study valve amp design on your own. Teaching you a to z, am afraid, is very tough here in the forum.
You are mixing dc resistance with OT's reflected primary load. Again, a plate choke coil has no secondary winding so it does not have any reflected load. DC resistance, inductance (at given frequencies) and capacitance are the role players here. For paralleled 3a5 you need minimum 100 Henry at 10ma whatever the DC resistance is.
Please note a plate load choke, a resistor and an output transformers are three different devices with three sets of different electrical characteristics. If you want to load the paralleled 3a5 plates with vanilla power resistor you need to use minimum 12K, 15K is better. As I said before, you need to size your B+ accordingly.
Dear supernut, we request you to follow a schematic exactly or chances are you will be frustrated with end result. You can modify but you need knowledge to do that. If you don't find the parts available for this schematic please select other schematic with power supply. We want to see you successful with your project, please don't try battery DHT it is super difficult. Not easy. I have seen people with years of experience to give up to tame battery DHT.
Regards
You need to study valve amp design on your own. Teaching you a to z, am afraid, is very tough here in the forum.
You are mixing dc resistance with OT's reflected primary load. Again, a plate choke coil has no secondary winding so it does not have any reflected load. DC resistance, inductance (at given frequencies) and capacitance are the role players here. For paralleled 3a5 you need minimum 100 Henry at 10ma whatever the DC resistance is.
Please note a plate load choke, a resistor and an output transformers are three different devices with three sets of different electrical characteristics. If you want to load the paralleled 3a5 plates with vanilla power resistor you need to use minimum 12K, 15K is better. As I said before, you need to size your B+ accordingly.
Dear supernut, we request you to follow a schematic exactly or chances are you will be frustrated with end result. You can modify but you need knowledge to do that. If you don't find the parts available for this schematic please select other schematic with power supply. We want to see you successful with your project, please don't try battery DHT it is super difficult. Not easy. I have seen people with years of experience to give up to tame battery DHT.
Regards
Thank you so much Mr. Minhaj I understand many things better. Vanilla power resistor of 15K need B+ about 250VDC to get 100VDC 10mA.
For using Choke of 140H 8mA 4360R DC impedance, refer to Schematic of Mr. Audiowize need B+ 165VDC to get 130VDC 8mA
Thank you so much again Mr. Minhaj. I will gradually study as your recommendation.
Can you hint me how to get value of 15K resistor in placed of 150H choke? if it is not bothering you much. If it is nonsense question, I am apologized and you not need to answer. I understand. don't worry If this project can't be build. I will stick with my old 6080 HP amp and abstinence my passion of better quality beyond 6080 HP that I have.
For using Choke of 140H 8mA 4360R DC impedance, refer to Schematic of Mr. Audiowize need B+ 165VDC to get 130VDC 8mA
Thank you so much again Mr. Minhaj. I will gradually study as your recommendation.
Can you hint me how to get value of 15K resistor in placed of 150H choke? if it is not bothering you much. If it is nonsense question, I am apologized and you not need to answer. I understand. don't worry If this project can't be build. I will stick with my old 6080 HP amp and abstinence my passion of better quality beyond 6080 HP that I have.
3a5 parallel ra is about 4.5k ohms x 3 =13.5k ohms round to 15k ohms
3a5 parallel ra is about 4.5k ohms x 20 henry =90 henry round to 100 henry
A plate choke acts like a reactor, plate resistor does not. Two ate different.
Thank you Mr. Supernut I don't understand many things better after 30
3a5 parallel ra is about 4.5k ohms x 20 henry =90 henry round to 100 henry
A plate choke acts like a reactor, plate resistor does not. Two ate different.
Thank you Mr. Supernut I don't understand many things better after 30
Thank you so much Mr. Minhaj for everything you mention here. These are very valuable knowledge for me. 30 years in this hobby is a very happy time (due to you can make many good sound equipments). Take care of yourself and enjoy very good sweet music with 3A5 and good Headphone.
After reading all infromation of many experts. I must study further about this 3A5 HP amp first to avoid further nonsense questions. Thank you very much again.
After reading all infromation of many experts. I must study further about this 3A5 HP amp first to avoid further nonsense questions. Thank you very much again.
wish you best of luck. Please keep in touch. By the way I don't use 3a5 to drive HP.
audiowise,
No first hand experience here about 3a5 driving headphone. Do you think loading 3a5 with 15k resistor with parafeed 10k:150 transformer in turn will drive 50 ohms hp? If yes, can you provide a schematic to supernut including B+ and filament supply?? Telling you so because drawing a schematic in a PC is not my strong hold.
Otherwise supernut may use a 10K:150 10ma lineout transformer and bingo.
Regards
audiowise,
No first hand experience here about 3a5 driving headphone. Do you think loading 3a5 with 15k resistor with parafeed 10k:150 transformer in turn will drive 50 ohms hp? If yes, can you provide a schematic to supernut including B+ and filament supply?? Telling you so because drawing a schematic in a PC is not my strong hold.
Otherwise supernut may use a 10K:150 10ma lineout transformer and bingo.
Regards
Sorry, as an inductive component a 89 H choke doesn't have a constant impedance. Instead, the impedance always is proportional to frequency. Neglecting DC resistance, a 89 H inductor will match an impedance of 2k5 at a frequency of ~4.5 Hz.
Placing an inductor instead of an ohmic resistor has the advantage of less voltage drop. I.o.w. you'd need to increase the supply voltage to have the same effect.
Best regards!
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