Here's the math required to calculate the power and supply requirements of an amp.
The Honeybadger is a 3 output pair amp. The rule of thumb to calculate a safe output power you add up the total power rating of all of the output devices and divide by 5. 150W (this is the power rating of most output devices) devices x 6 = 900 / 5 = 180W RMS.
To calculator the full load DC supply voltage you would get from your 49-0-49 VAC transformer you would multiply the voltage by 1.41 then subtract the rectifier voltage drop. 49 x 1.41 - 1.2 = ~68 VDC.
To estimate output power of the amplifier you subtract 15V (average loss for 8 ohm output due to supply sag and efficiency of the amp) from the supply voltage, then multiply that x .707 to calculate the output voltage swing of the amp. 68 - 15 = 53 x .707 = 37.5VDC. Divide that by 8 Ohms to calculate the output current. 37.5 / 8 4.6875 = 4.6875 amps. Multiply that by the swing voltage. 4.6875 x 37.5 = 176W. Your transformer is pretty much perfect for 8 ohm speakers.
For 4 ohms your power supply will likely sag a few more volts. A 27V swing will put you in the maximum output range for this amp. 27V / 4 = 6.75 amps x 27V = 182W. Divide 27 by .707 to get the peak swing voltage. 27 / .707 = 38V. Add roughly 20V for supply sag and efficiency = 58VDC supply voltage. Add rectifier loss of 1.2 = 59VDC. Divide by 1.41 to get your AC voltage. 59 / 1.41 = 42-0-42VAC transformer.
To calculate the VA rating required for the transformer to safely put out full power sine waves all day (100% duty cycle), double the output power rating of the amp, so 180W x 2 = 360VA / channel. If you don't plan to do extended full power testing of the amplifier into a dummy load you could easily get by with a transformer half that size though. Music will never put that sort of strain on an amplifier.
The Honeybadger is a 3 output pair amp. The rule of thumb to calculate a safe output power you add up the total power rating of all of the output devices and divide by 5. 150W (this is the power rating of most output devices) devices x 6 = 900 / 5 = 180W RMS.
To calculator the full load DC supply voltage you would get from your 49-0-49 VAC transformer you would multiply the voltage by 1.41 then subtract the rectifier voltage drop. 49 x 1.41 - 1.2 = ~68 VDC.
To estimate output power of the amplifier you subtract 15V (average loss for 8 ohm output due to supply sag and efficiency of the amp) from the supply voltage, then multiply that x .707 to calculate the output voltage swing of the amp. 68 - 15 = 53 x .707 = 37.5VDC. Divide that by 8 Ohms to calculate the output current. 37.5 / 8 4.6875 = 4.6875 amps. Multiply that by the swing voltage. 4.6875 x 37.5 = 176W. Your transformer is pretty much perfect for 8 ohm speakers.
For 4 ohms your power supply will likely sag a few more volts. A 27V swing will put you in the maximum output range for this amp. 27V / 4 = 6.75 amps x 27V = 182W. Divide 27 by .707 to get the peak swing voltage. 27 / .707 = 38V. Add roughly 20V for supply sag and efficiency = 58VDC supply voltage. Add rectifier loss of 1.2 = 59VDC. Divide by 1.41 to get your AC voltage. 59 / 1.41 = 42-0-42VAC transformer.
To calculate the VA rating required for the transformer to safely put out full power sine waves all day (100% duty cycle), double the output power rating of the amp, so 180W x 2 = 360VA / channel. If you don't plan to do extended full power testing of the amplifier into a dummy load you could easily get by with a transformer half that size though. Music will never put that sort of strain on an amplifier.
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Ah, sorry, I didn't understand, I believed 360VA stereo, instead of 360VA/channel. Then 800VA is actually good...
Unluckily, because of the chassis I will/can use, I'm forced to choose a mono PSU. The piece of furniture that will host the amp allows me a width of no more than 33 cm. I already own a modushop 3U mini dissipante, which is 40 cm deep and has a useful width of 25 cm. Hence I believe that mono PSU is mandatory...
Unluckily, because of the chassis I will/can use, I'm forced to choose a mono PSU. The piece of furniture that will host the amp allows me a width of no more than 33 cm. I already own a modushop 3U mini dissipante, which is 40 cm deep and has a useful width of 25 cm. Hence I believe that mono PSU is mandatory...
Well that was short lived blew again
The same channel went out again same problem R24 went up in smoke again after several weeks of no problems! This time it happened while playing at regular listening volume. I got to think I am about ready to throw in the towel can’t trust my build on this one!
The same channel went out again same problem R24 went up in smoke again after several weeks of no problems! This time it happened while playing at regular listening volume. I got to think I am about ready to throw in the towel can’t trust my build on this one!
Yes this is just a rule of thumb / rough estimate to be used in the design stage to see how many output devices you should use. Proper full load testing is better but it's a little late after the amp is built. At that point failure means replacing blown parts and figuring out what to do to keep it from blowing up again.
So I just want to reiterate what I was saying before I am running my HB rails at +/- 62vdc. My speakers are Magnepan MG IIC's . A load rated at 5 Ohm and sensitivity of 84dB. A heck of a load w/o a doubt. I play them loud many times maxing out the capabilities of the HB. I need more Watts at times. My outputs on the HB are 21193/194's. So why am I not having problems with the rail voltages this high with this kind of load. Been using this combo for probably 3-4 years now. I'm not disagreeing with the experts on this forum just trying to have a better understanding.
Okay guys, just went back to work and my brain is cooked, need a sanity check please.
Looking at the snubber for a 115v trans with the sec at 45v. the standard .15uF cap and a R of 954.
I'm trying to make sure I have enough power rating on R954 to make sure it has a long and happy life. I think I remember Mark, or someone saying you want 2-3 times the max to ensure good life and service.
So, with those numbers I got about 47.2mA as the wattage through the resistor. Can someone check me on this... I have a 1/4 and 1/2 watt Rs and was just going to use the 1/2 to have a large margin, but not sure my addled brain has the math right.
Thnaks
JT
Looking at the snubber for a 115v trans with the sec at 45v. the standard .15uF cap and a R of 954.
I'm trying to make sure I have enough power rating on R954 to make sure it has a long and happy life. I think I remember Mark, or someone saying you want 2-3 times the max to ensure good life and service.
So, with those numbers I got about 47.2mA as the wattage through the resistor. Can someone check me on this... I have a 1/4 and 1/2 watt Rs and was just going to use the 1/2 to have a large margin, but not sure my addled brain has the math right.
Thnaks
JT
I'm far from an "expert" but here's my take on it. A properly designed amplifier has a lot of safety margin built in. A 8 ohm amplifier design needs to safely drive a 4 ohm load at full power with room to spare otherwise it would never stand up to the peaks and dips of a speaker or crossover impedance curve (modern day DIY crossovers are often terrible loads to drive) The MJL21193/4 devices you chose are 200W devices giving better power handling than most and work great in a EF2 design amplifier, but they are known to self destruct in more modern EF3 designs. You may simply have come up with a combination that works. I'm not personally familiar with Maggie's, possibly their impedance curve doesn't have a big hole in it like many conventional speaker do. At the design stage it's usually best not to go with the luck of the draw though.
EF2 and EF3 are output staged designs. Moderate power amplifier often were 2 stage emitter follower (EF2) designs consisting of drivers and output devices. High power designs are often 3 stage emitter follower designs consisting of pre-drivers, drivers and output devices to lighten the load on the VAS section of the amplifier. One of the quirks of an EF3 design is it needs really fast output devices, otherwise they won't shut off fast enough and suffer shoot through / cross conduction causing self destruction.
Ostripper's Slewmaster amp with the Wolverine input stage is basically the high power version of the Honey-Badger with a 5 pair EF3 output stage more suited for the power range you are running. Slewmaster - CFA vs. VFA "Rumble" It's a great amp and I think it's actually easier to build. The MJL21193/4 output devices were the first ones they noticed this self destruction happening in.
Ostripper's Slewmaster amp with the Wolverine input stage is basically the high power version of the Honey-Badger with a 5 pair EF3 output stage more suited for the power range you are running. Slewmaster - CFA vs. VFA "Rumble" It's a great amp and I think it's actually easier to build. The MJL21193/4 output devices were the first ones they noticed this self destruction happening in.