If you can figure out what shorted, it would be wise to check other components close by in the circuit. There may have been a quick current surge through a couple transistors damaging them. At least test them in circuit with a meter set on diode test before powering back up. This may save a set of output devices from smoking later. They really stink up your house.
yes, but not as bad as speaker elements, but then again thats just me.
I had a couple of chinese speakers while testing I burned it and had to air the house in 20 degrees below... I got the heebie jeebies from the smell
I had a couple of chinese speakers while testing I burned it and had to air the house in 20 degrees below... I got the heebie jeebies from the smell
Wishborn,
Sorry to hear about your amp & speakers, That really sucks! I sincerely hope the remainder of the damage is minimal.
"The use of the symbol for Ohms (Omega, Ω is optional, and is most commonly left off, since it is irksome to add from most keyboards. The letter "R" and the "2k2" conventions are European, and not commonly seen in the US and other backward countries . Other variants are 0R1, for example, which means 0.1 Ohm"
I honestly haven't encountered this value system prior to DIYA, but will freely admit that I like it significantly better!
Sorry to hear about your amp & speakers, That really sucks! I sincerely hope the remainder of the damage is minimal.
The following is from ESP. I found it funny:
"The use of the symbol for Ohms (Omega, Ω is optional, and is most commonly left off, since it is irksome to add from most keyboards. The letter "R" and the "2k2" conventions are European, and not commonly seen in the US and other backward countries . Other variants are 0R1, for example, which means 0.1 Ohm"
I honestly haven't encountered this value system prior to DIYA, but will freely admit that I like it significantly better!
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new resistor vs old.
checked almost every transistor against the other working card. Everything came back ok!
Nais. I reset bias again... just because and start over.
at 56V rail and 50mv bias is there a way to know how far up it works in class a?
channel gets about 40 degree C. so I recon another 10 degree is mighty fine.
https://cloud.midtbo.pw/index.php/s/JiSi8H96Y8BMzn3
checked almost every transistor against the other working card. Everything came back ok!
Nais. I reset bias again... just because and start over.
at 56V rail and 50mv bias is there a way to know how far up it works in class a?
channel gets about 40 degree C. so I recon another 10 degree is mighty fine.
https://cloud.midtbo.pw/index.php/s/JiSi8H96Y8BMzn3
A push pull ClassAB amplifier stays in ClassA as long as both outputs control the output current.
This holds true up to approximately twice the bias current.
If one sets the bias voltage to 50mV across the two 0r33 emitter resistors, then the output bias current is 75mA
The ClassA maximum current will be ~150mA, or about 92mW of ClassA into 8ohms.
I see, but in this case we have 0R22, but it was only to see the ballpark figure.
SOUNDS great either way.
My Honey Badger have played well for about half a year. Recently i discovered that one channel was cold. The other channels heatsink was normaly warm. I demounted the cold channel, but since both diodes lighted up normaly, I took the chance to connect my variotransformer. Offset was measured to a normal level of 1.2mV. I started to test with a low power and a CD player with variable output connected. I played ok at very low level but started to distort when the level rised. At this low power 0mV(zero) was measured between the testpins. All transistors was B-E measured. All except output tested the normal 0.6V. Output transitors measured a little bit below 0.5V.Testpower was rised to +/-34V DC. Still 0 mV between testpins, but when I regulated the biaspot, I was able to measure 4.5 mV bias. Biaspot was now at max(clicked).I did some other measurement: Over R14:8.25 V and over R27: 0.525 V. Nothing wrong here. With a bias 4.5 mV the channel still play very distorted. To be absolutly sure I desoldered all output transistors. They all tested well. With all transitors healthy and other measurement ok except for the bias, I do not understand what is wrong and where to search to get the correct bias I once had. I need help.
Eivind S
Eivind S
I like 2k2 much better as regular text can fade off the decimal and you can get 22k when it was supposed to be 2.2k. This has happened to me before and I appreciate the foolproof nature of 0R22 vs .22 which can sometimes be mistaken for 22 ohms.
Honey Bear? Winnie the Pooh isn't exactly badass...
Ok, 'nuff trolling...
First of all, read Rod Elliots explanations about linear power supply design.
As I understand it, the Honey Badger was designed with a rail voltage of approximately +/- 65 VDC in mind. The build guide recommends a mains transformer with 45-0-45 VAC windings, and a 600 VA rating or higher would be fine for a stereo version of the Honey Badger.
However, the Honey Badger will work well with different rail voltages and transformers. However, the build guide is a bit shy on this point. I don't know the sensible limits for optimal operation, and I often read that lower PSU voltages are recommended for low impedance speakers. I have to admit that I don't understand this recommendation.
In my (slightly simplified) view, the PSU voltage defines the limit of the output voltage where the amp will start clipping (ignoring the transistor losses). Of course, for a given output power, low-impedance loads tend to draw more current and at lower voltage swings than high-impedance loads. But this alone (again in my view) does not warrant a recommendation for lower supply voltages – there must be some other aspects that come into play here, and I don't understand what they are. I'd say it would best to make sure the power supply provides enough voltage for high-impedance loads and has sufficient capacity for high currents to drive low-impedance loads.
Well, maybe my thoughts are all wrong (and somebody please correct me).
In any case, it would be cool if the build guide could be expanded with some hints and explanations about dimensioning a suitable power supply.
45+45Vac transformer should be enough for 200W+200W into 8+8ohms
That would normally use a 600VA transformer.
But that will need approx 1000W of semiconductor in each output stage.
That would be a 3pair stage with 170W, or 200W, devices.
This could not be used with 6ohms, nor with 4ohms speakers.
That would normally use a 600VA transformer.
But that will need approx 1000W of semiconductor in each output stage.
That would be a 3pair stage with 170W, or 200W, devices.
This could not be used with 6ohms, nor with 4ohms speakers.