Slides and video links updated courtesy of AudioMaker.tech | First Watt | Linear Integrated Systems
BAF Slides Nelson Pass | AudioMaker
https://www.youtube.com/watch?v=Xk8CubrqTYU
Have a nice day
BAF Slides Nelson Pass | AudioMaker
https://www.youtube.com/watch?v=Xk8CubrqTYU
Have a nice day
My first prototype is up and running.😀
I had tried to get it all on one breadboard, but on first test the input transformer was picking up hum.
So, I now have the power supply on one (the original) board, and the circuit + heatsink + input transformer on the new board.
Setting up the bias needs a steady hand on the adjuster pot, but 4.64v is the setting right now.The test voltage takes a while to stabalise, so only adjust the bias in small steps and wait till the test voltage stabilises,it can take several minutes. 4.7v is a good starting point.
Sound quality in mono with an old speaker seems very good, and can't wait to get the second unit finished and listen in stereo.
I had tried to get it all on one breadboard, but on first test the input transformer was picking up hum.
So, I now have the power supply on one (the original) board, and the circuit + heatsink + input transformer on the new board.
Setting up the bias needs a steady hand on the adjuster pot, but 4.64v is the setting right now.The test voltage takes a while to stabalise, so only adjust the bias in small steps and wait till the test voltage stabilises,it can take several minutes. 4.7v is a good starting point.
Sound quality in mono with an old speaker seems very good, and can't wait to get the second unit finished and listen in stereo.
Congrats Pre 65
Exciting
My input transformer primary and secondary winding have 4 market dots like on schematic.
Think i do connect them that way.
Attachments
Do your heat sink run burning hot?
Not at all with my computer fans running.😀
Without the fans as the heatsinks got hotter I found the bias kept needed adjusting to compensate, so I thought fans were a better option.
Ok thanks Pre65
guess with 3.2A my heat sinks are not over sized.
I do use for "triode" feedback big wire wound 220 Ohm resistor to the input of transformer
all loop made by the similar structure wire materials not film or metal oxide.
After practical experiments i know in this position is music friendly configuration.
Don't believe me resistors_mills_mrc haha
guess with 3.2A my heat sinks are not over sized.
I do use for "triode" feedback big wire wound 220 Ohm resistor to the input of transformer
all loop made by the similar structure wire materials not film or metal oxide.
After practical experiments i know in this position is music friendly configuration.
Don't believe me resistors_mills_mrc haha
Beauty DIY work Pre65
Excellent !Do you solder add resistor at the signal input ?
In case if preamp are capacitor coupled only
Beauty DIY work Pre65
Do you solder add resistor at the signal input ?
In case if preamp are capacitor coupled only
No, my preamp is an Audionote copy with output transformers.
Pre65 you are first Nr 1
Diyer who build them correctly.Amplify music with such SE sound particular ?
Here is my pair in action. The extra PSU is just for the fans.
naah
more porn please , then recognition 😛
Do you connect your preamp output transformer with the input transformer of Schade 50 ?
Was going to use switch mode power supplies but changed my mind and bit the bullet and ordered the caps.
Still need to purchase a couple of 600VA transformers.
Still need to purchase a couple of 600VA transformers.
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Why did you change your mind?
I recently heard the pre65 amps at a DIY event in England driving a pair of open baffles. They sounded fine though it was difficult to tell much given the acoustics of a large reception sized room with unforgiving speaker placement. The heat sinks measure 13" x 8" x 3" and barely get warm when the fan is running.
There are photos at Ray's Retirement: Owston - a visit to DIY Audio Land
The amp sounded good enough to persuade me to build a pair when I get back to the US. I have enough heat sinks and I am going to go the SMPS route. I had wondered about doing a 48 volt version but after discussion with pre65 I will go with 60 volts. Hopefully my Mouser order will be waiting for me at home and I will get them done before September when I head off to Oz.
ray
I recently heard the pre65 amps at a DIY event in England driving a pair of open baffles. They sounded fine though it was difficult to tell much given the acoustics of a large reception sized room with unforgiving speaker placement. The heat sinks measure 13" x 8" x 3" and barely get warm when the fan is running.
There are photos at Ray's Retirement: Owston - a visit to DIY Audio Land
The amp sounded good enough to persuade me to build a pair when I get back to the US. I have enough heat sinks and I am going to go the SMPS route. I had wondered about doing a 48 volt version but after discussion with pre65 I will go with 60 volts. Hopefully my Mouser order will be waiting for me at home and I will get them done before September when I head off to Oz.
ray
I would use SMPS definately. This is single-ended class A. Current is constant from power supply.
The schematics I have seen here have a variable current source, so actually
the draw is only constant on average. The draw will vary temporarily
from 0 to about 2X bias current, depending on the "gain" of the current
source.
This means that your SMPS needs to be rated more than twice the bias.
You can fix this by using a constant current source, but you get an efficiency
and performance hit.
the draw is only constant on average. The draw will vary temporarily
from 0 to about 2X bias current, depending on the "gain" of the current
source.
This means that your SMPS needs to be rated more than twice the bias.
You can fix this by using a constant current source, but you get an efficiency
and performance hit.