Would two 160va dual 24v toroids from Apex Jr.Home Page be good for the premium dual mono lm3875 from audiosector on 6ohm speakers? Is there a better option for a similar price?
24V transformers would give you about 34V rails, that might be a bit high for 6 ohm speakers, what does the datasheet say?
Datasheet just has 8ohm specifications:
DESIGN A 40W/8Ω AUDIO AMPLIFIER
Given:
Power Output 40W
Load Impedance 8Ω
Input Level 1V(max)
Input Impedance 100 kΩ
Bandwidth 20 Hz–20 kHz ±0.25 dB
Equations (5), (6) give:
40W/8Ω Vopeak = 25.3V Iopeak = 3.16A
Therefore the supply required is: ±30.3V @3.16A
The build manual from audiosector says:
"When looking over the curves a speaker with a nominal impedance of 4 ohms tend toward 25V rails with a reasonable margin of safety, while voltages above 35V are still well within the range for 8 ohm speakers. This shows that transformers with 18-22V secondaries are well within reason for many common commercial and DIY speakers. A transformer with 25V transformer secondaries can also be successfully with less of a safety factor."
DESIGN A 40W/8Ω AUDIO AMPLIFIER
Given:
Power Output 40W
Load Impedance 8Ω
Input Level 1V(max)
Input Impedance 100 kΩ
Bandwidth 20 Hz–20 kHz ±0.25 dB
Equations (5), (6) give:
40W/8Ω Vopeak = 25.3V Iopeak = 3.16A
Therefore the supply required is: ±30.3V @3.16A
The build manual from audiosector says:
"When looking over the curves a speaker with a nominal impedance of 4 ohms tend toward 25V rails with a reasonable margin of safety, while voltages above 35V are still well within the range for 8 ohm speakers. This shows that transformers with 18-22V secondaries are well within reason for many common commercial and DIY speakers. A transformer with 25V transformer secondaries can also be successfully with less of a safety factor."
I found toroidal transformers with 200va power and 20v or 22v output for $29 each from Antek. I assume these would be more suitable? I really have no idea what any of that means ive just been trying to research a lot.
On page 10, graph Output Power vs Supply Voltage has curves for 4, 6 and 8 ohm speakers. 6 ohm shows a max output at 33V before falling off, so less than that is a good idea.
A 22V transformer would give you about 31V rails, which is what I would go with as long as you aren't intending to run 4 ohm speakers with it in the future. That voltage will work quite well with 8 ohm speakers if you want to use those at some point.
A 22V transformer would give you about 31V rails, which is what I would go with as long as you aren't intending to run 4 ohm speakers with it in the future. That voltage will work quite well with 8 ohm speakers if you want to use those at some point.
thanks for the input.
So, 200 va per channel is not overkill? would the 100 va be better? (there is no in between)
So, 200 va per channel is not overkill? would the 100 va be better? (there is no in between)
160VA or 200VA would power a stereo amplifier adequately.
100VA would just about power a monoblock.
160VA for a monoblock is good, but that is two transformers and two PSUs and two chassis. Getting expensive.
100VA would just about power a monoblock.
160VA for a monoblock is good, but that is two transformers and two PSUs and two chassis. Getting expensive.
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