In limbo... certainly, but soon to be born again as a butterfly...all Stassisesss as Dodossess in Limbo?
I've changed the internal layout, swapped the channel around so the FE is at the back, found a couple of bigger heatsinks for the FE boards and going to mount the transformer vertically once the proper mounting brackets turn up...then we are back in business...
all Stassisesss as Dodossess in Limbo?
I’m making some slow progress, it’s been busy at work and with the Family, I’m trying to finalize the power supply…
Question for you folks, how do we calculate the Thermistor’s value to use for path to Ground? I see most of the folks use CL-60 but I’d like to understand why is that and if current rating or resistance is the deciding factor.
Thanks in Advance….
10R or more , to ensure proper isolation
CL or bigger, to ensure that NTC is stronger than your mains fuse, in case of meltdown, I mean - BigBadaBoom
CL or bigger, to ensure that NTC is stronger than your mains fuse, in case of meltdown, I mean - BigBadaBoom
Beauty........... would blossom in The Beast
Thanks ZM, your explanation makes sense to me, I'll find some good ones and give it a try!!
CL-60, or not
Alex,
Check out Mark's analysis of the CL-60 and his recommendation:
Not thrilled with CL-60 inrush limiter in USA/160W Class A First Watt designs
Alex,
Check out Mark's analysis of the CL-60 and his recommendation:
Not thrilled with CL-60 inrush limiter in USA/160W Class A First Watt designs
Dang!
Thanks ZM!
Sorry Alex!
No need to apologize GnuB, I appreciate you chiming in, yes I was asking about the Ground to Chassis NTC application but that was a very interesting readout that you recommended, and well all thermistors I'm using in this Amplifier are Ametherm brand, excellent company with excellent support and costumer service, 100% recommended.
Rebuilt with a much better layout. Stacked PSU and the FE boards at the back, closer to the inputs. Also, transformer vertically mounted.
Just in the process of setting the bias, which is quite a slow process with these amps.
Just in the process of setting the bias, which is quite a slow process with these amps.
I also added bigger heatsinks for the FE driver transistors.
More caps...I need shares in cap manufacturers...
Once it is biased up I'll run a couple of signals through it before hooking it up to speakers.
Many, many thanks for your help ZM 🙂
More caps...I need shares in cap manufacturers...
Once it is biased up I'll run a couple of signals through it before hooking it up to speakers.
Many, many thanks for your help ZM 🙂
Amp finally built, biased at 210mA, and I managed tonight to run it up and do a little testing..
The last two traces are on a 8R dummy load. Both channels behaved the same.
Rail voltages are +/-35Vdc.
Bottom trace is amp output
Top trace in the amp output
The last two on load. Bottom trace is amp output
The last two traces are on a 8R dummy load. Both channels behaved the same.
Rail voltages are +/-35Vdc.
Bottom trace is amp output
Top trace in the amp output
The last two on load. Bottom trace is amp output
Last edited:
The man said 50degC on those heatsinks, and we have 50degC on those heatsinks...lol210mA?
you're building damn refrigerator?
Traces look good, no?
is that 210mA for complete OS, or is it 210mA per vertical pair ?
I mean, I'm just checking ......
graphs are looking cool
how it sounds?
I mean, I'm just checking ......
graphs are looking cool
how it sounds?
210mV measured across a emitter resistor in the OS. Resistors are 1R, so 210mA.
No idea what power output that equates to, but the heatsinks and plenty toasty 🙂
And during the rebuild I spotted one NPN OS transistor I had forgotten to solder. All fixed now. I blame old age.
How's does it sound? I've not tried it yet, I have to lug it up two flights of stairs, it weighs a fair chunk, to wire it up to m'speakers. Hopefully tomorrow night, though I might sneak a listen first thing tomorrow morning. 🙂