diyAB Amp - The "Honey Badger"

[currentflow]

Originally Posted by danielwritesbac

Hey, I was wondering if I could use 35vdc rails in case I happened to have 2 way speakers and didn't need to crack up the vocals coming from the madly shaking woofer (aka didn't quite need the 150 watts when 60 would do) or in case I have 4 ohm speakers that need good current but didn't quite need as much voltage, then could I use 42vdc rails?

I guess I just need a briefing on what rail voltages work well for this amp. Is it specific to 60vdc rails or can I use less without getting into a lot of modifications?

Thanks!!

Hi,

OS's post #171 diyAB Amp - The "Honey Badger" would suggest that the amplifier would work with 15VDC rails, certainly fine at +/- 42V. But would you need all of the output pairs for that supply voltage?

[danielwritesbac]

Originally Posted by currentflow

Hi,OS's post #171 diyAB Amp - The "Honey Badger" would suggest that the amplifier would work with 15VDC rails, certainly fine at +/- 42V. But would you need all of the output pairs for that supply voltage?

A). Thank you very much! Perhaps there's some common transformers usable that we may already own.

B). In some case the 60vdc rails doesn't need the triple parallel output and there are other cases where the 42vdc rails needs triple parallel outputs and sturdy devices. That seems to vary by speaker load, right?

[currentflow]

Originally Posted by danielwritesbac

A). Thank you very much! Perhaps there's some common transformers usable that we may already own.

B). In some case the 60vdc rails doesn't need the triple parallel output and there are other cases where the 42vdc rails needs triple parallel outputs and sturdy devices. That seems to vary by speaker load, right?

Lower impedance loads such as 4 ohms might well require at least two pairs of output devices. In any event, if you were considering reducing the pairs, it would be worth recalculating the device dissipation / SOAR limits first.

[danielwritesbac]

Originally Posted by currentflow

Lower impedance loads such as 4 ohms might well require at least two pairs of output devices. In any event, if you were considering reducing the pairs, it would be worth recalculating the device dissipation / SOAR limits first.

Sure, for example, 16 ohm speakers used full range or 8 ohm speakers used 150hz for HT, or like you previously mentioned, much lower voltage in combination with 8 ohm speakers. Aside from a few odd applications, it looks like there's not many cases of wanting to reduce the amount of output devices.

[mattmcl]

Got my boards yesterday. The quality looks fantastic!

So, I'm pretty much a newbie and this is my next project. I'd be happy to contribute to the project by documenting my questions and problems as I go, perhaps it would help in adding to the current build doc and making this amp as noob friendly as possible.

For example, I'm currently stuck on parts selection- I'm not sure what type of resistor is best for each on the parts list. Ditto for caps. It would be great to have some help creating links to mouser products (or whoever). Perhaps we could even list which ones have the most effect on sound, and offer higher-end alternatives?

I'd be happy to start a spreadsheet on Google Docs and open it up to anyone who wants to help.

[mattmcl]

I started a Google Docs spreadsheet:

https://docs.google.com/spreadsheet/...U5vSUNoeHZlMXc

I got as far as I could. If anyone could help confirming what I've done and adding info for the rest, that would be great. I'll happily contribute this to the forum once done.

[danielwritesbac]

Originally Posted by mattmcl

I'm not sure what type of resistor is best for each on the parts list. Ditto for caps. It would be great to have some help creating links to mouser products (or whoever). Perhaps we could even list which ones have the most effect on sound, and offer higher-end alternatives?

Most resistors can be Xicon 1/4w carbon (nice thick pins and high quality); Most small capacitors can be silver mica (OStripper doesn't like ceramic used in compensation areas); Most large capacitors can be Panasonic FC (or other audio worthy electro--use diyaudio.com search feature).

That covers the majority; however. . .
I'd question for the exceptions:
Which resistors are to be larger/better than 1/4w carbon?
Which caps have little effect and may be econo caps?

The answers could make some good Build Thread material.

[Stormrider]

Considering the cost difference will be very minor, I would use metal film resistors. No reason to use carbon film these days. Anything over 1/2W should be metal oxide.

[danielwritesbac]

I think the answer looks more like this:
R23, 1/2w, 33R
R27, 1/2w, 68R
R32, 1/2w, 22R
R37, 1/2w, 2.2R
R38, 1/2w, 2.2R
R39, 1/2w, 2.2R
R40, 1/2w, 2.2R
R41, 1/2w, 2.2R
R42, 1/2w, 2.2R
R53, 1/2w, 22R
R54, 1/2w, 22R
R36, 1w, 150R
R49, 3w, 10R
R50, 3w, 10R
R43, 5w, 0.22R
R44, 5w, 0.22R
R45, 5w, 0.22R
R46, 5w, 0.22R
R47, 5w, 0.22R
R48, 5w, 0.22R
And, click here for a good document

[danielwritesbac]

Originally Posted by Stormrider

No reason to use carbon film these days.

In an audio purpose amplifier, I imagine that the specific use would be for Base Stopper; but, otherwise the metal film would either work better or the difference may be inapplicably small. Not conversely, but rather Likewise, I think that metal film works an tiny bit better for input load and many similar shunt tasks.

Here's an applied example:
If R5 and R2 (connects to input bases) resistors are changed for series pairs (390+430=820) of carbon then you will have faked the "clearer and less hard sound" of an LDR volume control without having to either purchase or build the LDR volume control. The difference/effect is tiny but apparently worth something. Although this effect is certainly less important than trying a few different capacitors at C3 and C1, it is still true that a more appreciable tone could make the capacitor selection routine (try five, choose the best) a bit easier, faster, or very slightly more pleasant. At least it is easy. Likewise good quality metal is probably the easiest way to best results from R3, R6, since metal film, more linear at all frequencies, might do a tiny bit better for shunting RF.

When both of those resistor ideas are employed and gain applied, then it may be noticeable, slightly. It looks like a good spot for some economical audiophile play. At least it isn't unusual that the specs of an ideal part depend so much on where it is used.

P.S.
It appears that opinion varies on this, and it appears that what causes the largest variance is that the compensations used in the amplifier can make some tonal differences that are considerably more important than a cap or resistor. Since one would not want to fine tune to indirectly address an issue, I wonder if HoneyBadger has some documented options for compensation adjustment or differences?