quick question: are there any transistors in this amplifier that have to be closely matched? If that's a yes, is it as much of a challenge to get matched quads/pairs as for comparison getting matched quad of 2sk170?
Is there also a "go-to" recommended psu circuit for it?
At the stage of calculating bom cost, checking component availability..
Is there also a "go-to" recommended psu circuit for it?
At the stage of calculating bom cost, checking component availability..
The more closely that the NPN/PNP pairs, including outputs and drivers, are matched the lower the THD + Noise.
A 300-500VA transformer, 2 30-50v secondaries, 2 bridge rectifiers, smoothing caps as big as will fit is all that is needed.
A 300-500VA transformer, 2 30-50v secondaries, 2 bridge rectifiers, smoothing caps as big as will fit is all that is needed.
Alright, the PSU seems to be simple enough.Universal PSU will do the job, just might need to recalculate the values for desired rails voltage/amp output power.
Speaking of the matched components. What's the potential deviation in thd and increase in noise for poorly matched components. I wonder if precise matching is critical in this case.
Also, statistically speaking, what's the usual distribution in I don't know... idss or hfe in the components used in this amp, do you need tons of them to obtain pairs/quads? Or It is fairly easy to obtain a let's say 2 pairs out of 20 output and or driver transistors?
I used MJL transistors from On Semi as outputs - these are matched to 10% in the factory. The input pairs were checked and the first pair gain matched to about 5% using my multimeter (whatever that meant). High gain on the input is important I believe. The others were used as supplied and not selected at all. The input and current source resistors were closely matched though. Ensure your transistors can handle twice the supply voltage of course.
Spent a great deal of time addressing the wiring to avoid ground loops.
End result was delightful and has been for 4 or so years.
Spent a great deal of time addressing the wiring to avoid ground loops.
End result was delightful and has been for 4 or so years.
I think I remember Pete saying high gain input transistors were the cause of oscillation in some builds.
yes, more caps gives you lesser ripple voltage....it is the size and the weight of your traffo that made a bigger difference...
This is a general rule of safety. Obeying it surely won't harm and keep us at the safe side. Anyway, all input stage transistors don't see more than one rail voltage each, hence can be chosen more conservatively, I think.
Best regards!
Technically speaking larger caps will give you slightly more power due to less ripple but it not the place to look if you chasing money power.
The transformer is the place to start.
Please refer to my schematic.
The problem was the zener diode and R19.
R19 was to large and the zener diodes power rating wasto high.
I posted a lot of information about this years ago and have helped many members out with this solution.
100 ohm base resistors into Q3 and Q4 can also help.
no brainier, a 20kg power traffo when compared to a 5kg traffo with the same terminal voltages will always come out on top....
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I have heard Johno's Honey Badger in action and it does indeed sound delightful through his Manzanita speakers.
Richard
Richard
Hello! I'm kind of a newbie building amplifiers, but I have some understanding in general electronics. These days I'm in the process of building myself a honey badger amp. I followed the BOM and got all of the components from either Mouser og Digikey. I have followed the build guide and completed the first channel of the amp with success and everything there is working as it should.
Now, the second channel is a different story. After hooking up the 10 ohm 1W resistors I had almost 3Volts across both resistors. I used my bench power supply at +/-30V and turned it off after a couple of seconds so nothing smoked. I have checked continuity and made sure there is nothing shorting on any of the heatsinks, I have checked all of the transistors out of circuit with a DMM and they all seem to be fine. Also made sure that the correct transistor is in the correct place and in the correct orientation. After this I tried another powerup at +-/10V just to be safe and still I had over 1 volt across the 10 ohm 1W resistors. I checked the output to ground, and there I had around 5V. I've tried connecting only the positive rail (with only +/-10V) that gives me 0V at the output. With only the negative rail connected i get -5V at the output. After all of this I replaced all of the transistors and still I get the same thing. I feel like I have checked everywhere on the pcb to look for anything that could short some of the components out, but I can't find anything wrong.
I'm using NJW0281/NJW0302 for output, MJE15030/MJE15031 for drivers and MJE340 for VBE.
I'm hoping that somebody can point me in the right direction for where to look for whatever the problem might be with this amp. Sorry for my english, it's my second language 🙂
Now, the second channel is a different story. After hooking up the 10 ohm 1W resistors I had almost 3Volts across both resistors. I used my bench power supply at +/-30V and turned it off after a couple of seconds so nothing smoked. I have checked continuity and made sure there is nothing shorting on any of the heatsinks, I have checked all of the transistors out of circuit with a DMM and they all seem to be fine. Also made sure that the correct transistor is in the correct place and in the correct orientation. After this I tried another powerup at +-/10V just to be safe and still I had over 1 volt across the 10 ohm 1W resistors. I checked the output to ground, and there I had around 5V. I've tried connecting only the positive rail (with only +/-10V) that gives me 0V at the output. With only the negative rail connected i get -5V at the output. After all of this I replaced all of the transistors and still I get the same thing. I feel like I have checked everywhere on the pcb to look for anything that could short some of the components out, but I can't find anything wrong.
I'm using NJW0281/NJW0302 for output, MJE15030/MJE15031 for drivers and MJE340 for VBE.
I'm hoping that somebody can point me in the right direction for where to look for whatever the problem might be with this amp. Sorry for my english, it's my second language 🙂
Hallo guys,
I have a small problem with my honey badger build and was hoping to get some help.
I was going to set the bias but noticed that I get 0v between tp1 and tp2. So I checked the base voltages of Q14 and Q15 with reference to ground. At Q14 I am getting about 2v and at Q15 about -0.09v. I can change both of these up and down with the trim pot.
It seems to me that the voltage into the VAS is shifted by about 1v or so. I have the exact same problems on both channels so it seems like I used a wrong resistor somewhere but I think I checked all of them and can't find the problem.
I was hoping one of you would have an idea from where this problem originates.
I have a small problem with my honey badger build and was hoping to get some help.
I was going to set the bias but noticed that I get 0v between tp1 and tp2. So I checked the base voltages of Q14 and Q15 with reference to ground. At Q14 I am getting about 2v and at Q15 about -0.09v. I can change both of these up and down with the trim pot.
It seems to me that the voltage into the VAS is shifted by about 1v or so. I have the exact same problems on both channels so it seems like I used a wrong resistor somewhere but I think I checked all of them and can't find the problem.
I was hoping one of you would have an idea from where this problem originates.
I would start by checkin wheter there is any connection between the heatsink and any of the transistors collectors. Maybe one of them is not properly insulated.
What did you find, might help another forum member.