Since you do, I strongly suggest that you expound on most of your postings rather than just say that you are sure about it because others, and that includes me, are not.
List the parts you don't, or can't, agree with & I'll see if I have the time to repeat all my contentious posts with an explanation that meets with your requirements.
BTW,
I'll guess that all my recent posts are basically repeats of earlier posts, many of which do go into the detail of how I arrive at my conclusions.
BTW,
I'll guess that all my recent posts are basically repeats of earlier posts, many of which do go into the detail of how I arrive at my conclusions.
I would like to see some more discussion on the topic of output. I plan on using this with 6ohm or less speakers. It seems that my plan of using a transformer with 45V secondaries is not appropriate for anything below 8 ohms. This will change many component choices in the power supply as well. What is a good reference that explains these topics and maybe includes the equations that were used to derive these results?
As far as I can tell from Andrew's posts, his calculations were based on an EF2, two pair output stage. Anybody paying even remote attention would know the diyAB has an EF2, three pair output stage with the target of 150W/8ohms, and the capability to drive light 4ohm loads.
His calculations in post #751 might be very applicable to those living in 240V countries, but most transformers in the US are specified for our actual line voltage, 120Vac. That means a 120Vac : 40-0-40 transformer here will not reach the target of +/-59Vdc, which is what is required to reach the 150W/8ohms goal. 45-0-45 may be a little over, with my guess being +/-62Vdc, or less under load, but this will be close enough.
His calculations in post #751 might be very applicable to those living in 240V countries, but most transformers in the US are specified for our actual line voltage, 120Vac. That means a 120Vac : 40-0-40 transformer here will not reach the target of +/-59Vdc, which is what is required to reach the 150W/8ohms goal. 45-0-45 may be a little over, with my guess being +/-62Vdc, or less under load, but this will be close enough.
personally , the "internet banter " between the two doesn't bother me the least . however that said , i wish that these two very knowledgeable people would continue their "discussion" in a manner that would be a contribution to this build thread .
then they can take it out to the parking lot
then they can take it out to the parking lot
re: XFMR voltage
I understand trying to get an approximation of OP power for a given XFMR but I don't think it's all that critical in the whole scheme of things:
1. music is dynamic, nobody listens to sine waves (test signals) OP power changes dramatically with different material even within the same track.
2. The actual dB change going from +/- 40 to +/- 45 VAC rails will be quite small with respect to speaker SPL's, I would almost say undetectable under most normal conditions.
3. Doubling the OP power gives a mere 3dB increase
I understand trying to get an approximation of OP power for a given XFMR but I don't think it's all that critical in the whole scheme of things:
1. music is dynamic, nobody listens to sine waves (test signals) OP power changes dramatically with different material even within the same track.
2. The actual dB change going from +/- 40 to +/- 45 VAC rails will be quite small with respect to speaker SPL's, I would almost say undetectable under most normal conditions.
3. Doubling the OP power gives a mere 3dB increase
BTW,
I asked this before
Has anybody done any testing of the finished badger?
Is there a post where I could find this info. I did look but could not find
Just curious...
jojod did......
depends on your choice of power traffo....i.e. choosing a 150vA traffo, voltages sag will be bigger so that your output trannies will be less stressed than with a power traffo of say 500va...
but even with a 500va traffo and a 6ohm load, a lot will depend on your listening habits, how loud you want to play...
give this amp a good heatsinking and you are go....
Just my 2 cents...If you've chosen a reputable manufacturer...It is properly sized...It will get the job done!! There will always be some voltage sag at high loads, that's life. There will always be losses, that's physics..
I would be more concerned with proper mounting location and ensuring you will not be injecting hum into the amp circuitry. Also, I would take caution not to inadvertently introduce a shorted turn with your mounting technique, this will surely take out fuses and/or your breaker...not good
Remember, many 'mid-fi' manufacturers intentionally undersize the XFMR because they know it won't be driven at high levels continuously
Hope this helps,
Regards
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