diyAB Amp The "Honey Badger" build thread

[Jamesblond]

Thanks Os. I remember reading something about it on this forum. Can't remember where, exactly.

It that diode implemented on the latest PCB version? I can't find it in the build guide, nor in the schematic and in the BOM. What does it connect to and in what direction? Which type should it be?

 

[ostripper]

Thanks Os. I remember reading something about it on this forum. Can't remember where, exactly.

It that diode implemented on the latest PCB version? I can't find it in the build guide, nor in the schematic and in the BOM. What does it connect to and in what direction? Which type should it be?

low reverse leakage type , anode to Q10 collector.

Have some fun , start at the "bav's" , look for low nano amp to pico amp reverse
leakage specs. higher voltage reverse voltage ratings (200V+).

OS

 

[Jamesblond]

Something like a BAV21? Ir ca 100nA at 200V.
Why is that "having fun"? 😉

[EDIT]
1N485B has Ir=25nA at 175V. Is that one better suited?

 

[ostripper]

Something like a BAV21? Ir ca 100nA at 200V.
Why is that "having fun"? 😉

[EDIT]
1N485B has Ir=25nA at 175V. Is that one better suited?

See , you answered your own question .... Fun ! 😉

As a guideline , for safety - the diode has to be de-rated >20% reverse breakdown
greater than the highest expected VAS waveform .... (which is rail total minus about
3 volts).
100nA takes THD down @ 3ppm , I have one model that is <50nA - about the same - with or without it.
If your rails are on the higher side and you never intend to "hard" clip this amp,
the diode can be omitted (another option). But , with low enough reverse
leakage , amplifier performance will be unaffected.
OS

 

[Gizmosis]

Hello!
Just started the building of a honey badger, but i think i did a little miss.
The deal is i used 22ohm 1/2W instead of 22ohm 1/4W , does it matter or need i change them ? sorry for stupid question and bad english.

 

[Renron]

JamesBlond, OS explained the BC clamp better than I could have. I just have not yet soldered it in, from OS' answer, I have no idea. OS will hopefully answer. He's been great about that.

Gozmosis, That is exactly what I did, on purpose. I ordered all 1/2W resistors instead of 1/4 watt, they fit all the holes just fine. No problems. your english is great!

OS, I answered all my own questions I had earlier asked. The answers were self-evident as I populated the boards. I was just looking at the schematics and not thinking , just looking. 🙂

 

[Gizmosis]

Good , then i don't need to unsolder :-D

 

[janusz]

In PAs I'm using 1W metalized resistors except for sections where low noise resistors are required or more than 1W is required. Overrating has some advantages.

cheers,

 

[AndrewT]

Metalised resistors to me sounds like metal film resistors.
Metal film resistors are low noise.

 

[Renron]

Talking resistor composition, will there be any noticeable difference using Carbon film vs. Metal film (R37 - R42) at the base leg?

 

[danielwritesbac]

Talking resistor composition, will there be any noticeable difference using Carbon film vs. Metal film (R37 - R42) at the base leg?

If in the presence of higher voltage, carbon may be preferable at base stopper locales.

However, the quality of the resistor will probably matter more than the materials used in its construction. So avoid the chinese bargain resistors with the almost hair thin leads. Xicon will do fine. Koa might do better.

 

[Renron]

Thank you Daniel,
Yep, 63V rails. Not sure of the MFG, but the leads are substantial and tolerances are very good., 1%. These are the 1/2W sizes.

Ron

 

[Jamesblond]

Does anyone have experience with Multicomp (resistors) parts? That's what my vendor supplies most. They have Vishay/Dale, but much more expensive.

 

[jwilhelm]

I've used Multicomp metalfilm 1% resistors for 20 years with excellent results.

 

[AndrewT]

Some of my stock is multicomp 1% 600mW metal film 100ppm/C and I have not experienced any problems with them in comparison to the equivalent product from Philips, or Vishay.
I use these for most duties and when I need higher power, I series and/or parallel connect them.

 

[Renron]

In the diyAB build guide PDF written by JojoD818 under the Bias Calculations heading it reads;
"Bias calculations:
For 100mA bias per pair, measure about 44mV between TP1 and TP2.
I = 44mV (measured between TP1 and TP2) / 0.44
I = 0.1A = 100mA"

Shouldn't the next to last line read,
I = 44mV (measured between TP1 and TP2) / .044 ?
I think the decimal is in the wrong place. or am I missing something?
Ron

 

[Jamesblond]

@Jwilhelm and Andrew: thanks!
This will be the way to go, then. I may have to ask the supplier for a better price, though, since the entire package is turning out more expensive than I had previously anticipated...

 

[Renron]

Terry,
I was looking at the photos of your amp, I think you are about to short out C7 with the heatsink, looks like only a hair apart from the legs.
Ron

 

[Jamesblond]

Hi,

a question on C4: is that a bi-polar electrolytic? What is it's voltage rating?

Also: can I run a dual psu HB from one soft start pcb? Or should I install two?
And am I correct when I say that one speaker protector pcb switches two amp channels / speakers?


Thanks!

 

[Renron]

JamesB,
dual psu from one soft start? depends on the rating of the 2 TX (transformers) and the rating of the soft start device.
One speaker protection USUALLY controls both channels.
C4. Is a bi-polar and I'm using a MUSE ES 220uF 50V, needs to be high quality cap.
Ron