Grazie william2001, allora:
nessun cortocircuito con il dissipatore di calore
tensione circa 23 VDC (che aumenterà con il nuovo alimentatore)
R7, R8, R10...........0,0 VDC!!!!
Offset CC..............circa 20 VDC!!!!! (che non si muove nemmeno ruotando P1)
mio Dio..
nessun cortocircuito con il dissipatore di calore
tensione circa 23 VDC (che aumenterà con il nuovo alimentatore)
R7, R8, R10...........0,0 VDC!!!!
Offset CC..............circa 20 VDC!!!!! (che non si muove nemmeno ruotando P1)
mio Dio..
meaning of "across resistor" is - black probe on one pin of resistor, red probe on second pin of resistor
on the other hand - when it's said "voltage at some point", it is always referenced to GND, so black probe on GND (where is convenient) and red probe at said point
I know it's not easy going through google translate ...... so ask freely whatever you need, to be sure that you got what was meant
on the other hand - when it's said "voltage at some point", it is always referenced to GND, so black probe on GND (where is convenient) and red probe at said point
I know it's not easy going through google translate ...... so ask freely whatever you need, to be sure that you got what was meant
as it was said:
so, be sure that you confirm and write here both rails
and, P1 situation?
I purchased a used stock J2 from Reno hifi ten years ago and it’s been sitting in one of my bedrooms ever since.
As it hasn’t seen voltage since Mark tested it, I believe the soft start procedure is to use a single phase variac to slowly dial up the AC voltage with the J2 loaded with my pair of cheap but serviceable Panasonic SB2765 speakers, and driving those 8 ohm speakers to moderate volume for several minutes?
I’d like to use the J2 to drive a pair of speakers which Troy Crowe will build for me, using my midwoofers.
https://josephcrowe.com/blogs/news/altec-416-8b-in-100l-sealed
The horn might be the ES450, though the ES290’s Fc would likely cross far better acoustically, assuming a horn that large can sit safely atop my midwoofer cabinets. https://josephcrowe.com/products/3d-cad-plans-for-es-290-biradial-horn-horn-no-1670
We also haven’t yet settled on a two way https://jblpro.com/en-US/product_documents/2450-pdf
or three way design, though if a tweeter is included it like the midrange https://bcspeakers.com/en/products/hf-driver/archive/2/8/DCM50 or https://www.bmsspeakers.com/index.php-111.html?id=bms_4591 or https://www.rcf.it/en/products/product-detail/nd950-2.0
will be a compression driver, such as the RCF ND350, or better.
https://www.rcf.it/en/products/product-detail/nd350
And in a horn like this. https://josephcrowe.com/products/es-2000-biradial-wood-horn
But if all three drivers are 8 ohms the total system impedance will likely be no more than 4 ohms anywhere along the audible range, and at some frequencies even lower. The good news is that these compression drivers need ~ 1 watt to produce > 100db @ 3 ft for the low SPLs I will need at 11 ft away in my ~ 3000 sq ft room. And I will only have the 98db midwoofers playing down to ~ 70Hz at 80db, below which my subs take over. https://www.rythmikaudio.com/F12SE.html
However, what concerns me are the apparent rapidly rising distortion levels at ~ 5 to 7 wpc into 4 ohms and less, as shown in these measurements. https://www.stereophile.com/content/first-watt-j2-power-amplifier-measurements
Might there now be any circuit mods which could substantially reduce harmonic and/or IM distortion, at least around these lower output levels? If I cannot do the mods myself then Scott probably can. https://www.sgcustomsound.com/
don't bother yourself with too much technicalities
J2 is a Pleasure Machine, and you'll like it with your big drivers
if you still decide that you want to try something with lower THD, try XA25
if you like it, sell J2, add some greenies and buy new guy
J2 is a Pleasure Machine, and you'll like it with your big drivers
if you still decide that you want to try something with lower THD, try XA25
if you like it, sell J2, add some greenies and buy new guy