diyAB Amp The "Honey Badger" build thread

Very good caps you are using Ejje - expensive as well. My most expensive are 8 22mF/63V RIFAs. Their ESR (my measurement) is about 60mOhm. That's not less than ESR of all my other caps - 80V Panasonic and Nichicon Fine Gold. RIFA's are big and heavy and I expected lower ESR. Bought them long time ago from the UK.

From Polish audio sites I heard that toroids from toroidy are rather power shy unless you go for the most powerful ones. That was one of the reasons I hesitated to buy from them. As I need a couple of new toroids 2x45 i'll go for 625VA multicomps from element14.

cheers,
 
Very good caps you are using Ejje - expensive as well. My most expensive are 8 22mF/63V RIFAs. Their ESR (my measurement) is about 60mOhm. That's not less than ESR of all my other caps - 80V Panasonic and Nichicon Fine Gold. RIFA's are big and heavy and I expected lower ESR. Bought them long time ago from the UK.

From Polish audio sites I heard that toroids from toroidy are rather power shy unless you go for the most powerful ones. That was one of the reasons I hesitated to buy from them. As I need a couple of new toroids 2x45 i'll go for 625VA multicomps from element14.

cheers,

Yeah, they where not cheap but I'd like to think that they will last me a very long time :) Maybe my choice of transformers wasn't the best, hehe.
For now I'm very happy with how it performs.

Here is a better pic at one of the caps..
 

Attachments

  • Cap.jpg
    Cap.jpg
    87 KB · Views: 670
Honey Badger BOM - Mouser

I'm new to this and (in retrospect) probably should have picked an easier amp to build on my first try, however I'm learning a lot but I seem to be stuck on PSU snubber calcs.

Could anyone help with the PSU snubber component values?

Perhaps you could take a look at the attached BOM and provide feedback on any mistakes you see too?

My plan is to have 200W at 8ohms the transformer is 1000VA 230v to 2x50v.


Thanks!
 

Attachments

  • HBBOM.zip
    57.6 KB · Views: 154
I'm new to this and (in retrospect) probably should have picked an easier amp to build on my first try

Don't worry. The Honey Badger is a tried and tested design with good documentation. Just take your time and you'll be fine!

however I'm learning a lot but I seem to be stuck on PSU snubber calcs.
Could anyone help with the PSU snubber component values?

Don't loose your sleep thinking about snubbers. The optimum values of the snubber parts depend on the characteristics of your transformer. You could easily build your amp without any PSU snubbers at all, the amp will work perfectly fine. You could also use some generic/typical snubber parts. If you want to get the snubbers to perfectly match your transformer(s), take a look at the Quasimodo.
 
I'm new to this and (in retrospect) probably should have picked an easier amp to build on my first try, however I'm learning a lot but I seem to be stuck on PSU snubber calcs.

Could anyone help with the PSU snubber component values?

Perhaps you could take a look at the attached BOM and provide feedback on any mistakes you see too?

My plan is to have 200W at 8ohms the transformer is 1000VA 230v to 2x50v.


Thanks!
2x40Vac allowed me to get ~170W into 8ohms.
My modelling software predicts that 2x45Vac will get to well over 200W into 8ohms.

On that basis you don't need 2x50Vac to meet a 200W target.
 
Hi Medi, use the NJW 3281/1302 output transistors with the TO3P case rather than the MJL types with the TO264 case which are too big to fit comfortably to the DIY pre-drilled heatsinks.

Thanks Johno, I was planning on drilling the heatsinks myself as I'm buying the chassis from HIFI2000 rather than the DIYAUDIO store (I'm in the UK).

Unless all the cases come with the heatsinks pre-drilled (I think they are the supplier for DIYAUDIO)? I'll ask the supplier.
 
Don't worry. The Honey Badger is a tried and tested design with good documentation. Just take your time and you'll be fine!



Don't loose your sleep thinking about snubbers. The optimum values of the snubber parts depend on the characteristics of your transformer. You could easily build your amp without any PSU snubbers at all, the amp will work perfectly fine. You could also use some generic/typical snubber parts. If you want to get the snubbers to perfectly match your transformer(s), take a look at the Quasimodo.


I'll omit it for now then, thanks!
 
Yes, both your pocket and the design.
A higher voltage from the PSU will result in a higher dissipation in all devices passing current from those rails.
That means selecting devices that can tolerate the extra dissipation.
And now that you have these higher dissipations you need bigger heatsinks to get rid of that heat.

If its just a matter of device dissipation and Heatsink, he can do the following
1. use use MJL devices
2. use a speed limited fan, xrk uses them often.

This could just save heavy expenses.

But I wonder if its just the devices and heatsinks that need attention.
 
Member
Joined 2016
Paid Member
Hi All. I was just wondering if there is a more detailed description of how this circuit works. I am fine with 90% of it. I just don't see exactly how the output of the differantial pair drives the vas. It looks like the output of the current mirror (top left of the schematic) is attached to two pnp transistors which form a VAS cascode (top center of the schematic) which is then supplying the bias current for the vbe multiplier which drives the output transistors.

If someone can provide me so more details or point me to a older post discussing this that would be awesome.

Cheers

Stuart
 
Last edited:
thanks prasi I guess I stated the question poorly I was after amperage I am wondering how we deduce the needed ampereg the mains fuse supplies the universal power supply with the an 8445 tranny for a power supply of 62 volts to the hb amp prasi recommends 5amp at the mains and 7 amps at the hb board this seems backward to me but sometimes my logic is bad
 
The transformer manufacturer normally will recommend a maximum input current for their products. If not you can calculate it by dividing the VA rating of the transformer by your line voltage. Normal industrial practice is to multiply this number by 125% for inrush, but this isn't really required with a good soft start circuit. Add any other current draws in your amplifier (control transformers, ect) and you have your fuse rating.

Rail current will be much higher than mains current. The mains voltage is stepped down increasing current available, plus there is a considerable current reserve available in the supply capacitor bank. If you install too light of a rail fuse you will get distortion resembling clipping at high output, and you will see some discolouration and deformation of the fuse element as it starts to melt on current peaks, then re-solidifies (fuse distortion). I use a separate output stage over-current protection and use 15A rail fuses normally in my builds.