Hi,
When tweaking an amplifier for best performance (THD / spectrum analyzer) we see that the performance is different for each power level. With my average speakers (for example Pied Pipers) the actual power needed is barely higher than 1 watt. With most music and listening conditions 100 mW will be fine. The amplifier I'm still working on (KT150 PP) will easily give 75 Watt per channel, so I have a lot of headroom (more than ever will be needed).
What is a good rule of thumb to determine on which power level to "put" the best performance, keeping in mind the speaker efficiency. At 1 Watt (as in my case)? Higher? Lower? For 1 Watt I got THD below 0.10%, so I'm already pleased with the results.
What are your experiences with this?
Regards, Gerrit
When tweaking an amplifier for best performance (THD / spectrum analyzer) we see that the performance is different for each power level. With my average speakers (for example Pied Pipers) the actual power needed is barely higher than 1 watt. With most music and listening conditions 100 mW will be fine. The amplifier I'm still working on (KT150 PP) will easily give 75 Watt per channel, so I have a lot of headroom (more than ever will be needed).
What is a good rule of thumb to determine on which power level to "put" the best performance, keeping in mind the speaker efficiency. At 1 Watt (as in my case)? Higher? Lower? For 1 Watt I got THD below 0.10%, so I'm already pleased with the results.
What are your experiences with this?
Regards, Gerrit
There are two main test
Thd vs power
Thd vs frequency
The first give you an idea how the Thd will increase with power and it must have an “linear” andament ( different from ss) until the max nominal power
The second must have a costant line prportionally with power test
And it is difficult to obtain due the limit of OT at low and high freq.
The result is structly related to quality of OT mainly
Thd vs power
Thd vs frequency
The first give you an idea how the Thd will increase with power and it must have an “linear” andament ( different from ss) until the max nominal power
The second must have a costant line prportionally with power test
And it is difficult to obtain due the limit of OT at low and high freq.
The result is structly related to quality of OT mainly
Of course this all matters, but with certain settings you can tweak the performance. When optimized at 10 Watt it may not be optimized for 1 Watt. And there may also be differences for different frequencies. For example I can adjust the CCS for higher / lower plate current in the driver tubes and measurements will show differences.
For now I’ll go for max. performance @ 1 Watt. It measures good. It sounds (very) good.
For now I’ll go for max. performance @ 1 Watt. It measures good. It sounds (very) good.
One good circuit have a good performance at different level and this must be the goal
About CCS it is sand and not vacuum
🙂
About CCS it is sand and not vacuum
🙂
Hi!
I'd optmize for the average level I'd use it, as long as the amp doesn't perform bad outside this average power level.
Below this average, it must perform really good, cause you'll be using it at this range during low levels music program.
For higher power levels, you have to determine the minimum requirements, if needed, consider the tradeoff of moving the performance to a higher level.
Find the balance.
Very close to maximum power is not much important, since THD will explode and, since you have a lot of headroom, it makes no sense to optimize up to be clipping point - let's say at 90% maximum power is ok, in your case. So if max power is 75W and up to 67W you get the reasonable THD, it's ok and it doesn't matter if above 67W amp will go to THD 10%. Just "rate" your own amp as 67W at xx THD.
I'd optmize for the average level I'd use it, as long as the amp doesn't perform bad outside this average power level.
Below this average, it must perform really good, cause you'll be using it at this range during low levels music program.
For higher power levels, you have to determine the minimum requirements, if needed, consider the tradeoff of moving the performance to a higher level.
Find the balance.
Very close to maximum power is not much important, since THD will explode and, since you have a lot of headroom, it makes no sense to optimize up to be clipping point - let's say at 90% maximum power is ok, in your case. So if max power is 75W and up to 67W you get the reasonable THD, it's ok and it doesn't matter if above 67W amp will go to THD 10%. Just "rate" your own amp as 67W at xx THD.
