In post #20 Nelson said a bit under 3mA, so you can try a lower value resistor. He also said that it is not critical.
Post #20
I would like to incorporate a pair of these into MOFO's to bump up the gain then run them with a waynes preamp.
My Mofo monoblocks are being run off of two 19V Dell supplies with 6.7A.
Could I run the Front ends off the same 19V supplies or should I get something with more voltage to run the two boards?
My Mofo monoblocks are being run off of two 19V Dell supplies with 6.7A.
Could I run the Front ends off the same 19V supplies or should I get something with more voltage to run the two boards?
I would just stick with the 48V SMPS and Mark's filter myself.
I assume each monoblock has a 19V supply so the FE would also be fed 19V. Unfortunately 19V is not enough to get the FE to output enough voltage to have the Mofo output its maximum power of about 12W.
The correct concept but sorta missed the target.
What you are speaking of is resistor distortion (mostly 3rd HD) caused by resistor thermal effects as shown in PPM on the resistor datasheet.
RN55 resistors typically come in three PPM categories; 100PPM, 50PPM and 25PPM. Resistors heat and cool at a rate of 2 times the frequency of the applied audio signal. When the thermal mass of the resistor resistive element is constant 100PPM parts have 4 times the distortion of 25PPM parts.
RN60 resistors also come in three PPM categories; 100PPM, 50PPM and 25PPM. RN60 resistors produce less distortion because of greater thermal mass, reduced temperature change compared to their smaller RN55 brothers.
Thanks DT
Definitely not a bad idea to experiment with different psu topologies.
But, that layout might be an issue with signal and power wires not playing nicely with each other.
Try that setup with the transformer placed outside the chassis. If you like it, maybe look for a larger chassis for better layout options.
But, that layout might be an issue with signal and power wires not playing nicely with each other.
Try that setup with the transformer placed outside the chassis. If you like it, maybe look for a larger chassis for better layout options.
Oh yes I have used VRDN with my FE initially but later moved to Salas dual mono as I had the psu boards as well as toroidals 🙂
Much better improvement over smps for sure.
Much better improvement over smps for sure.
Better layout would have the FE boards on the right side, on the same side as the RCA jacks and pot. Place the PS board and transformer on the left side, with the transformer at the front, far away from the signal wires and jacks. Place the AC/IEC connector at the left side of the back panel.
Thanks for the input guys, I think I am gonna just bite the bullet and buy another case for the power supply and have them seperate.
Have you actually compared ? What’s the improvements?
I’m using a 48Vdc SMPS + Mark’s SMPS filter and it’s very good.
Thanks
Eric
Prominently the base has become more tighter and overall presentation seems to be much more fluid and effortless. By the way with Salas I had to drop the psu voltages to +/-21vdc as using 18vac rails.
Hi guys, I recently purchased a set of the FE 2022. I noticed that it is the V0R1 version, which I understood is slightly different from the V0R0. There are a P1 trimpot and a C6 cap which are not mentioned on Nelson's original BOM. Could someone of you please clarify this particular?
Thank you very much and regards.
Gaetano.
Thank you very much and regards.
Gaetano.
Here is post 686 that I distilled into a single sheet PDF for my own reference. Papa's words slightly edited.
Far from being a complaint: Just got a kit and they are exactly as they are represented in the STORE.
The reason for writing is there had been a post or two that made it sound like ALL of the needed resistors were included with the kit. Thinking this was true, even though the store says nothing to this effect, I did not bother to order the needed resistors. So UPS gets another delivery fee from me.
Hope to have it playing music over the weekend.
Thanks for the kit to our great patron and the DIY STORE.
One thing that I wonder about - is with many using power supplies greater that 50 volts should caps C4 and C5 rated at 25 volts in the BOM be uprated to reflect the power supply being used?
The reason for writing is there had been a post or two that made it sound like ALL of the needed resistors were included with the kit. Thinking this was true, even though the store says nothing to this effect, I did not bother to order the needed resistors. So UPS gets another delivery fee from me.
Hope to have it playing music over the weekend.
Thanks for the kit to our great patron and the DIY STORE.
One thing that I wonder about - is with many using power supplies greater that 50 volts should caps C4 and C5 rated at 25 volts in the BOM be uprated to reflect the power supply being used?