PC with adequate software powered on , sound card connected and adequately set ( you need to read software help/manual for that)
output from SCard connected via balanced cable to that part on left side
signal goes to volume pot , regulating amount of voltage going to DUT (say that you need 1W at dummy load , so connect CRO across dummy load and set for 8Vpp for 8R)
signal goes to DUT either through RCA or XLR cable
then - taken from dummy load ends , via aligator clips or whatever , route signal back to interface box , lower right side
it goes to second volume pot , which sets amount of voltage going back (again 6.3mm balanced cable) to SCard input ; set dBFS in software to your liking with that pot
all that reff. to sketch in post #75
and yes - I did all measurements with same drek on Babelfish M25
useful enough
output from SCard connected via balanced cable to that part on left side
signal goes to volume pot , regulating amount of voltage going to DUT (say that you need 1W at dummy load , so connect CRO across dummy load and set for 8Vpp for 8R)
signal goes to DUT either through RCA or XLR cable
then - taken from dummy load ends , via aligator clips or whatever , route signal back to interface box , lower right side
it goes to second volume pot , which sets amount of voltage going back (again 6.3mm balanced cable) to SCard input ; set dBFS in software to your liking with that pot
all that reff. to sketch in post #75
and yes - I did all measurements with same drek on Babelfish M25
useful enough
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Its been bothering me for years, ready to get busy! And hopefully be an inspiration for others who want to do same, but without no how like me!
Thanks for the help,
Russellc
Probably shouldn't have mentioned that. Shame spiral...what is required to measure that? And here I thought it was fine...less good sleep tonight!
Russellc
)
From post #423:
while on bench , you can check Aleph AC gain
for that - run any Freq you know that your AC DVM can cope with (400-500Hz) , level - some round value on output - volt or so ; then simply measure AC voltage across source resistor of any lower positioned mosfet, write down; then measure AC voltage across source resistor of upper mosfet , write down.
then write here
Now to find Aleph J schematic and figure out upper from lower mosfet!
Of course I have no signal generator, 2 old tube ones in basement I never restored.
Have new tubes for them somewhere or other...Maybe some app does it these days.
Russellc
while on bench , you can check Aleph AC gain
for that - run any Freq you know that your AC DVM can cope with (400-500Hz) , level - some round value on output - volt or so ; then simply measure AC voltage across source resistor of any lower positioned mosfet, write down; then measure AC voltage across source resistor of upper mosfet , write down.
then write here
Now to find Aleph J schematic and figure out upper from lower mosfet!
Of course I have no signal generator, 2 old tube ones in basement I never restored.
Have new tubes for them somewhere or other...Maybe some app does it these days.
Russellc
yup
you're clogging this thread
not I didn't do the same , plenty of times
I'll stop with this topic here!
Russellc
same prog you're using for THD Spectra can be used as sig gene
it probably already have that function , even as standalone generator
for best results , choose lower freq ,so even DVM at AC can be used for measurement
say 440Hz
dummy load at output , of course
simple pc tone generator - Google Search
even some phone app can do the job as gene , just be careful with volume
it probably already have that function , even as standalone generator
for best results , choose lower freq ,so even DVM at AC can be used for measurement
say 440Hz
dummy load at output , of course
simple pc tone generator - Google Search
even some phone app can do the job as gene , just be careful with volume
It might be interesting to start a H2/H3 spreadsheet.Two sets of post adjustment values.
1. H2 H3 adjusted to a pre determined ratios and phase. note the dc offset voltage at the junction of R3 & R4.
2. P3 adjusted to personal taste, note H2 H3 values, that would be interesting in it's self.
In all cases, note the idss; if there is enough data, patterns may emerge.