Typically, in a general sense, you might be correct
What if you have a 2 ohm nominal speaker system?
What if you are driving a system with efficiency/sensitivity over 100db/w/m?
What if it is a line array?
20V out into 8 ohm = 25wrms 12V out into 2 ohms = 36wrms
What is the efficiency of your system? A system with well over 100db/w/m is 2X? 4X? 8X more efficient than typical systems?
Line array's, well just double that output again due to the doubling of the wavefront from line speakers.
Wimpy? A hamburger-loving character from the Popeye cartoon? "I would gladly pay you on Tuesday, for a hamburger today"?
Build it we will see, IMO 12v will be a problem especially in the bass...
> I will next try the toshiba with 24 V and reduced bias.
No, next try Toshiba balanced.
And when you are done with that and still not happy, PM me for further experiments.
Patrick
FLG comment about the impedance reminded me that in balanced my load would be 2 ohm, and so I tried balanced with 12.5 V and it sounds clean. But I have only one channel running.
Listening now.
D.
I use a Picotech 4424 as this what I have at work but, from what I see out there, sound cards have better performances.
The distortion magnifier from Cordell is on the wish list
One thing of the balanced business I do not like is that I don't know how to test things, as I do not have a balanced generator. I have to try with the DAC and test tones.
D.
For completeness, my toshiba setup has matched source resistors (0.22R) and matched jfet with degeneration trick. I did not have matched toshiba output.
The textbook F5 with IR not only have higher THD, but the 2nd harminic is dominant.
With the toshiba, in the right channel, I did not have to do anything, on the left had to reduce a bit one of the 10 ohm resistors of the jfet. This was done soldering over the resistor a 5k multiturn trimmer. The parallel value was around 2.3k.
D.
> For completeness, my toshiba setup has matched source resistors (0.22R) and matched jfet with degeneration trick. I did not have matched toshiba output.
That is the next step. No point doing the degeneration trick if the output devices are not matched, at least for Vgs. So there is still potential to get even harmonics lower. And you need to get the noise floor down to see the results more clearly.
Patrick
That is the next step. No point doing the degeneration trick if the output devices are not matched, at least for Vgs. So there is still potential to get even harmonics lower. And you need to get the noise floor down to see the results more clearly.
Patrick
Most distortion tests are done at low frequencies, like 1kHz. So 24 bits / 192kHz sound cards are fine. And there are many at very low cost and with balanced I/Os. One member of my own team (not the F5X team) is using, e.g. Terratec Phase X24. Many software to choose from. So search around or ask in the appropriate forum.
Patrick
Patrick
EUVL, Nikon.... Thanks for the leads on the sound card approach.... I'm a student of "old school" and was thinking only about stand-alone analyzers,uintil I saw your responses.....
You've given me a good idea regarding a card-based analyzer. I'll be hitting the Test forums and I'net today.....
You've given me a good idea regarding a card-based analyzer. I'll be hitting the Test forums and I'net today.....
School? WAKE-UP!!! I went to school years ago...Now it's wake up for real time!!! No excuses!!! ie:My dog ate my mouse after the cats caught it!!!
I just had to go thru closing on my house, the apprasall, the fire inspection that was supposed to take place before that, the insurance inspection that was also supposed to be part of that paperwork... I'm finally done!!! I own a house... And have no money anymore...
Now I have all the new house crap to do... but, it's really not a new house so I acctually have more to do...
A stereo system is up high on the list
flg
I just had to go thru closing on my house, the apprasall, the fire inspection that was supposed to take place before that, the insurance inspection that was also supposed to be part of that paperwork... I'm finally done!!! I own a house... And have no money anymore...
Now I have all the new house crap to do... but, it's really not a new house so I acctually have more to do...
A stereo system is up high on the list
flg
I saw in some other thread that I said something regarding F5 heatsinks? well I don't actually remember that but, I do have data from my heat sink testing some would be interested in.
As before my room was about 22C and an 8" tall section of H.S.U.S.A. 10.08" was suspended from the outside edges allowing for free flowing convective air. This time though I used only the inside 2 FETs on Kero pink pads. I put 23.5Vds and 1.3A through them and let them stabilize for a few hours.
Device temp was about 67C and 1/2" away the sink was about 50C. at the top of the sink the temp was 47C.
I would say an 8" section of the 10.08" H.S.U.S.A. is more than enough for 1 channel of standard F5. I might also expect a 6" section to be just fine for the standard configuration with 1.3A bias.
As before my room was about 22C and an 8" tall section of H.S.U.S.A. 10.08" was suspended from the outside edges allowing for free flowing convective air. This time though I used only the inside 2 FETs on Kero pink pads. I put 23.5Vds and 1.3A through them and let them stabilize for a few hours.
Device temp was about 67C and 1/2" away the sink was about 50C. at the top of the sink the temp was 47C.
I would say an 8" section of the 10.08" H.S.U.S.A. is more than enough for 1 channel of standard F5. I might also expect a 6" section to be just fine for the standard configuration with 1.3A bias.
School? WAKE-UP!!! I went to school years ago...Now it's wake up for real time!!! No excuses!!! ie:My dog ate my mouse after the cats caught it!!!
I just had to go thru closing on my house, the apprasall, the fire inspection that was supposed to take place before that, the insurance inspection that was also supposed to be part of that paperwork... I'm finally done!!! I own a house... And have no money anymore...
Now I have all the new house crap to do... but, it's really not a new house so I acctually have more to do...
A stereo system is up high on the list
flg
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