diyAB Amp The "Honey Badger" build thread

[mattmcl]

Sweet, thanks!

Are you using the TO-220 mica hardware kits for all the transistors?

[Variac]

EZ enough on perf,
We do have PSU boards in the store too. Might be out of stock ATM

Seems like on AB amps you don't see the Pi filter arrangement, with the resistors much
Probably because the amp has decent power supply ripple rejection. The resistors lower the voltage a little
and maybe the varying power draw of the AB amps is an issue..

Anyone know?

Originally Posted by danielwritesbac

Mouser parts CRC type Power supply, affordable and easily doable on perfboard?

[danielwritesbac]

Originally Posted by Variac

EZ enough on perf. We do have PSU boards in the store too. Might be out of stock ATM. Seems like on AB amps you don't see the Pi filter arrangement, with the resistors much. Probably because the amp has decent power supply ripple rejection. The resistors lower the voltage a little and maybe the varying power draw of the AB amps is an issue. Anyone know?

Short answer: R//D

The "D" can be series pairs of heavy duty TO220 diodes for constraining the resistor's voltage drop to ~1.4v, and these can be heatsinked to defer the heat away from the capacitors.

The "D" can be KBPC2501's with the two AC tabs cut off, thus creating a heavy duty ~1.3v diode unit that is easy to heatsink. Reverse voltage tolerance is not applicable at PI filter location. It is vital to check the polarity with a voltmeter prior to adding the paralleled resistor. That model is probably overkill on current handling, but easier to heatsink is an important feature. Heavy duty, lower voltage, diodes have less forward voltage drop at high amperage and less voltage drop means less heat. So, these big metal squares are easier to heatsink for two reasons.

When these ~1.3v diode units are parallel with the resistors (PI filter, the "R" in the CRC), the resistors do not explode. It is also possible to use resistors up to 1R for increasing/installing an open sound effect. Likewise it is not required to use ineffectively tiny resistor values in order to constrain voltage drop, since the diode unit takes over the job of constraining voltage drop.

Unlike a lower power amplifier, Honey Badger might easily pull down a resistor to 0.7v standard diode; however, two diodes in series (or the above described diode unit) might provide enough slack for the PI filter to work as expected.

R//D That's all I've got at the moment.

[AndrewT]

Originally Posted by danielwritesbac

Short answer: R//D

The "D" can be series pairs of heavy duty TO220 diodes for constraining the resistor's voltage drop to ~1.4v, and these can be heatsinked to defer the heat away from the capacitors.

The "D" can be KBPC2501's with the two AC tabs cut off, thus creating a heavy duty ~1.3v diode unit that is easy to heatsink. Reverse voltage tolerance is not applicable at PI filter location. It is vital to check the polarity with a voltmeter prior to adding the paralleled resistor. That model is probably overkill on current handling, but easier to heatsink is an important feature. Heavy duty, lower voltage, diodes have less forward voltage drop at high amperage and less voltage drop means less heat. So, these big metal squares are easier to heatsink for two reasons.

When these ~1.3v diode units are parallel with the resistors (PI filter, the "R" in the CRC), the resistors do not explode. It is also possible to use resistors up to 1R for increasing/installing an open sound effect. Likewise it is not required to use ineffectively tiny resistor values in order to constrain voltage drop, since the diode unit takes over the job of constraining voltage drop.

Unlike a lower power amplifier, Honey Badger might easily pull down a resistor to 0.7v standard diode; however, two diodes in series (or the above described diode unit) might provide enough slack for the PI filter to work as expected.............

Is this proposal and explanation of how it works gobbledegook or am I getting a bit too slow in the uptake of new ideas?

[Variac]

Daniel is a creative guy.........He likes using his own terms and explanations. Not everyone agrees with these...

[danielwritesbac]

Originally Posted by AndrewT

Is this proposal and explanation of how it works gobbledegook or am I getting a bit too slow in the uptake of new ideas?

Fortunately, I didn't give an explanation on how it works. But, here is one possible explanation in this link to Lenard Audio, with the PI filter removing discordant ripple distortion. I thought it a fascinating read.

In my previous post, I was merely proposing one way to constrain the heat and voltage drop of the "R" in the CRC power board. That is a totally orthodox CRC power supply when the amp is used at low/modest/normal power, since the catch diode isn't on.

Honey Badger is capable of a wide range of power output. I could not choose one perfect resistor value to support both low and high power; however, I could choose a resistor value to support low power use that is set parallel to a catch diode to support high power use when needed.

[AJT]

ok, i get it now, what you wanted to do was to make a CRC filter out of the psu and that you wanted to limit the drop in the resistor to 2 diode drops.....this is new to my eyes...congratulations for coming up with such a novel idea...

[danielwritesbac]

Originally Posted by Tony

ok, i get it now, what you wanted to do was to make a CRC filter out of the psu and that you wanted to limit the drop in the resistor to 2 diode drops.....this is new to my eyes...congratulations for coming up with such a novel idea...

Thank you. But I feel compelled to mention that when used with a high power amplifier All diodes on the power board need to be heatsinked to avoid capacitor heat damage (since ordinary connections are both electrically and thermally conductive), and the greater the forward voltage drop the greater the heat. I believe that we should expect the need to heatsink the diodes.

[danielwritesbac]

There is possibly an additional caveat--An open sound effect, aka miniscule reverb that could be good or could be wrong. I believe the fix for misbehavior is exactly the same--pile on more resistors at the cost of a less effective filter (very similar to adjusting an orthodox CRC to fit a higher power amplifier). My point of mentioning this somewhat controversial bit is that an effect may exist and it is adjustable when it isn't a surprise. I have not tested this C,R//D,C power filter for beyond 127 watts amplifier. Some fine tuning may be needed.

[naf]

my first channel HoneyBadger ...
it glow! it stable and it sing very good