diyAB Amp The "Honey Badger" build thread

use 3 pair @60+ V rails!!

I noted that Herve Delatraz uses a single pair of OP devices in his DarT Zeel amp, for 100watts@8/160W@4ohms. I'm thinking that two pair would be alright, with active protection against DC offset & overtemp -see kit I'm using:

MA9 S2 Clone 150W 150W 8ohm Poweramp Kit High End MJL4281A MJL4302A | eBay

BTW , what dynaudio (340/360/260)

The Dynaudio Foccus kit uses 17w75XL and D28/2 w/compensated 1st order X/O.
Mine is a 3 way tower with active woofer below 80Hz, so it reduces demands on amp.

-Chas
 
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I'm looking at building an amp for my system, and this could be ideal. Have there been any reviews yet or any frequency plots?

Thanks!

Frequency response is (below 1) 5hz-100k+ -flat .

Noise is better than -115db according to my sound card's spectrum analyzer.
I can't hear any hiss from this amp with full gain and an ear to the tweeter.
Much better than any mid priced home theater system amp setup.

Gain should be exactly 41.25db - any source should drive it to clipping.
A few builders have described it here in this thread. I think it is very neutral and reflects exactly what it sees at it's input.

With a proper supply it can really show you what any speaker is capable of -
LOT's of headroom - I've blown speakers just just for the hell of it :D -
Durable is another way to describe it.

Any other description would be subjective , the amp will be what you put into it (matching transistors/choice of transistors , 1% resistors,quality derated capacitors , chassis/general amp layout)... but even with recycled parts it
will beat a mass produced unit.

OS
 

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Hi All
Simple newbie question: what transformer should I be using for Honeybadger?
Will sometimes be listening at high volumes.
What VA? 600?
Voltage? 2 x 42? or should I use two transformers?
Simple answers please!
For just one clear answer, more information is needed.
Power:
If you put an ohmmeter into your speaker jack, does it say 3, 4, or 6 ohms?
Is the speaker a large 3-way or a 2-way?
What is the max power rating of the speaker?
Costs:
Do you want bigger stereo separation plus better dynamics (including bass) or do you want lower costs?
 
Hi Daniel
The speakers I have at present are Monitor Audio RX6, 6ohms, 90db sensitivity, Max power 125w. But I do want to upgrade them fairly soon. Not sure what too but something that could handle the Honeybadger with ease - Suggestions for DIY or off the shelf appreciated.

Not worried about costs, I want best!
 
........... Monitor Audio RX6, 6ohms, 90db sensitivity, Max power 125w.............
I suspect your MA RX6 are 4 to 8 ohms speakers with a 4ohm equivalent bass driver/s.
If this is the case, then design the amplifier to drive a 4ohms load. Not a 6ohms load.

Check the speaker schematic.
Measure the bass/mid resistance.

PSU design comparison:
. . . 8ohms . . . 6ohms . . . 4ohms
Vac . 35 . . . . . .35 . . . . . 35
VA . . 150 . . . . 225 . . . . . 300
mF . . 20 . . . . . 30 . . . . . . 40
 
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I am terribly confused by Antek - AN-4235 with the test conditions stating secondaries were parallel during the test. Normal hookup would be with the secondaries effectively series, but the problem is that the datasheet doesn't give any specs for using the transformer normally. This is a maximized core, minimized copper build (a giant core barely covered in thin gauge copper), so I assume that secondaries series normal use would perform a bit differently than their secondaries parallel test.
Question:
If I would like the equivalent of an old fashioned 5.7A 70VCT (35+35VAC Center Tap), to power each monobloc, then would I need Antek - AN-6238 transformers?
 

6L6

Moderator
Joined 2010
Paid Member
There is no doubt that the Antek spec sheets cause some confusion. Oh well. At least they have some measured data, many manufacturers or distributors don't even have that.

Something to keep in mind - in the description they state that " In most of the cases, this transformer can be output 20% more power from its rating at 60Hz power source without any problem."

If that isn't enough to settle your worries, then just buy the next bigger one.
 
I am terribly confused by Antek - AN-4235 with the test conditions stating secondaries were parallel during the test. Normal hookup would be with the secondaries effectively series, but the problem is that the datasheet doesn't give any specs for using the transformer normally. This is a maximized core, minimized copper build (a giant core barely covered in thin gauge copper), so I assume that secondaries series normal use would perform a bit differently than their secondaries parallel test.
Question:
If I would like the equivalent of an old fashioned 5.7A 70VCT (35+35VAC Center Tap), to power each monobloc, then would I need Antek - AN-6238 transformers?

you mean short circuit tests? the object of the test is to determine copper losses and so the testing calls for all secondaries of the "traffo under test" to be effectively shorted together, rated primary current is then allowed to flow using a variac to set a voltage that allows this....this procedure is common to all transformers undergoing such test...

add the copper losses(short circuit) and the core losses(no-load test) and you can get the efficiency of the traffo....to the average user, this is of no consequence....

a 600VA traffo for the honey badger is more than enough imho....
 

6L6

Moderator
Joined 2010
Paid Member
Question:
If I would like the equivalent of an old fashioned 5.7A 70VCT (35+35VAC Center Tap), to power each monobloc, then would I need Antek - AN-6238 transformers?

Ok, you lost me.

5.7A at 70vct is 400VA An Antek AN-4235 would be exactly what you are asking for.

38v+38v (or 76vct) at 600VA is 7.9A
(And even better, the Antek 6238 says it can flow 2x 38v windings at a total of 9.4A -- that's more than 700VA!)
 
5.7A at 70vct is 400VA An Antek AN-4235 would be exactly what you are asking for.
Tested secondaries parallel, but is secondaries series when I use it: Oops! Bit of a hard sell to say that doubling the length of the copper doesn't have any effect.

EDIT:
There was increased loss at secondaries, not at primaries. I've still got the Primaries parallel like the test conditions. So the discrepancy wasn't a factor of 2, but rather somewhat less. It is quite confusing to figure out specs that have a "somewhat" in them.
 
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I have a few questions....

In the build thread people are talking about a 2x45 Vac transformer 800va , if the speakers were 4 ohms what output power would that give? I wanted the amp to be flexible so I could use different speakers, maybe 8ohms at a later stage. I noted in one of your posts you said 45vac is too high for 4 ohm loads, what would happen? blow up?

2nd question (of many, yet to come). The PSU BOM states capacitors with a value of 10k uf to 22k uf, but some members are talking of just using 6k uf, what would the higher capacitance give, sound wise?

3rd question what is a snubber?

4th question - looked at some capacitors on Hi Fi collective and they we £15-£30, whilst others are talking of using 5usd capacitors. Would using more expensive be better, does it make any difference in a PSU? or should high quality caps be reserved for the amp?

That will do for now, hopefully be able to order something soon.
 
Ahh , question 1 is very timely. I am about to build some "mini badgers" in bridge mode for my sub. The trick for 4R seems to be lower Rail voltages. At 40-0-40VDC the badgers SOA doubles and at 30VDC doubles again. 2 bridged Badgers running with 35v rails would most likely drive a 2-4R sub at over 300W !!
(BTW , this would equate to a 26-0-26Vac trafo).
The SOA of even the lowly onsemi NJW pair is close to 7 amps at 30V(DC).
Of course , using the more robust MJL's will increase thermal dissipation and these have even higher SOA.


Q2 - Smaller main supply caps = more ripple.For 8R loads , I use 10Kuf x2 per channel. For lower impedance's, 15-20Kuf is suggested.
6Kuf would turn this amp into an OEM :D (higher ripple - less "punch")

Q3 - The "snubber" Snubber - Wikipedia, the free encyclopedia
in this amp (the 2 diodes) keeps the inductive load of the loudspeaker from destroying the output stage. The 3 amp diodes should have a short reverse recovery time. You see this technique applied to relay coils as well.

Q4 - Some audiophiles swear by esoteric capacitors. My take is that low esr
and MTBF are the main considerations.
The input cap should be high quality polystyrene ,very stable over time. The miller caps in the VAS should be silver-mica - very stable (temperature and value) no parasitic resonances.
ALL power supply caps can be any properly derated (panasonic , nichicon ,rubycon), low esr electolytic.

OS
 
Yes, both BOMs show the same. Just wondering if it is R15 & R16 that need to be 1%?

No, although making R15 and R16 1% wouldn't hurt, it is not that critical because each one is effectively paralleled to each side of trimmer R17. So using 1% or 5% doesn't matter.

R8 and R9 matters because they are in the CCS and makes changing R7 (CCS adjust) more meaningful.

HTH
 
I fail to see why R9 needs to be 1% and because of the R7 trimmer, R8 does not seem critical either... On the other hand, closely matched R15 & R16 have the potential to make R17 unnecessary (though it's good to have for fine dc offset adjustment)

I would like to hear OS's thoughts on this, though.