I checked voltage BPR resistors on SLB and adjusted around 420mv to 600mV (3A) with R101.
It changed Vds of LU from 2.7Vds to 4.7Vds.
I finally adjust Vds and bias.
A channel : 3.7Vds 530mV (2.65A)
B channel : 3.5Vds 570mV (2.85A)
Bias or Vds ... Which of 2 channel I must match ?
It changed Vds of LU from 2.7Vds to 4.7Vds.
I finally adjust Vds and bias.
A channel : 3.7Vds 530mV (2.65A)
B channel : 3.5Vds 570mV (2.85A)
Bias or Vds ... Which of 2 channel I must match ?
We just need to refer to the schematic. P121 is located at the inductor return to GND. P122 is located at the Source of the LU1014 JFET, and is same as input to inductor. So voltage across P122-P121 is the same as voltage applied to inductor. If inductor has Dcr of 0.6ohms, then I=V/R or 1.8v/0.6ohms = 3.0A bias current. That is assuming your choke DCR is a true 0.6ohms. Since you also measure same current across the resistors of the SLB and you got 2.65A, I would say that the DCR of the choke is closer to R=V/I = 1.8V/2.65A=0.68ohms. Close enough.
As far as matching the two channels, you don’t have to perfectly match them as long as bias current is close. But I wouldn’t match one at the detriment of having the other too different.
@xrk971
I finally adjust bias, Vds of LU.
A channel : 2.80 Vds, bias 610mV 3.0A
B channel : 2.90 Vds, bias 610mV 3.0A
I finally adjust bias, Vds of LU.
A channel : 2.80 Vds, bias 610mV 3.0A
B channel : 2.90 Vds, bias 610mV 3.0A
I finaly changed from smps to trafo and cap multiplier,and every things seems okay.I get 29,6v-I have tried to adjust the pot on the cap multiplier but nothing changes.
Is this normal?
Is this normal?
Yes, the cap Mx pot maybe changes a volt or so and really we should have made it a fixed value. You want about a 3v drop across the cap Mx to make sure it has enough drop to do its smoothing.
Very nice and neat build. How is it sounding?
Very nice and neat build. How is it sounding?
I pulled out my old LuFo Lite and fixed the broken halogen bulb. I added Mark Johnson’s Scourge front end from the VFET to provide some gain. It’s running well again and sounds great. Nice to have some signal gain from the Scourge. I’m running 30v supply on the Scourge inputs and 24v supplies on the main LuFo Lite amp.
This lamps are a bit too bright and a lamp shade makes this amp double as a lamp for the listening space.
This lamps are a bit too bright and a lamp shade makes this amp double as a lamp for the listening space.
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Enjoying the LuFo Lite as a headphone amp and desk lamp, fed by the LSA TT and Jhofland’s take on the Pearl 3phono stage followed by SMSL L90 preamp for volume control. Headphones include HE-400i, Status Audio CB-1 and OB-1.
Listening to Notes with Attachments by Pino Palladino and Blake Mills on vinyl. One of the finest recordings of experimental jazz.
Listening to Notes with Attachments by Pino Palladino and Blake Mills on vinyl. One of the finest recordings of experimental jazz.
I am listening through this small loud speakers,whit just a llitle EQ in the bottom and the top.And its easy to follow the bas guitar,the loudspeaker sounds bigger than they are,the highs and middle sounds natural.No doubt its a HQ amp,
Those are thick wires. One clue is if this MOT was for an EU microwave (230vac) or a USA/Canada/Taiwan microwave (120vac). The EU variety has too much DCR resistance. Have you bought it yet? Just measure it with LCR meter.I can't find information about its parameters Model: DPC-c6413FA
