No, I didn't try on batery but I think hum is not coming from the power suplly ,perhaps it's promblem becouse I eliminated the tone control as explained in the musical concept mod not sure. I'am just curious is some have similar problem with this preamp.
The new power supply is not over yet, I plan to finish it soon but right now the power supply is good and uses the LM317 & LM 337 regulators with 2x 4700uF Nichicon KA for audio capacitors and Elna Silmic II 2 x 1000uF, soft recovery diodes BYV 27/200 and conveniently quietly.
Power supply that I have not finished "Sulzer-Borbely supeer regulator" very quiet power supply, I also order from Ebay relay input selector to shorten the signal path, all capacitor is changed to Black Gate and Nichicon also replaced the RCA connectors, transformer instal Euro power supply connector etc. as can be seen in the pictures.
Power supply that I have not finished "Sulzer-Borbely supeer regulator" very quiet power supply, I also order from Ebay relay input selector to shorten the signal path, all capacitor is changed to Black Gate and Nichicon also replaced the RCA connectors, transformer instal Euro power supply connector etc. as can be seen in the pictures.
Hi, I too would like to upgrade power supply, upgraded transformer to toroidal and it sounded terrible, pre- amp became very hash to listen to. Quickly reverted back to old transformer, I realize now it would benefit from better power supply. My DH- 101 in stock form has no hum on line stage when volume is turned up full. No music. Phono stage has small amount of hum after ¾ volume with turntable plugged into source ,none without table plugged in.
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https://picasaweb.google.com/113336685910601049348/Desktop?authkey=Gv1sRgCNG5_dbT2qrlTA#
Reminder that I modified a '110. I changed the power receptacle to an IEC type. The original had become frayed. The center, earth ground, is connected to the chassis.
The signal ground is connected to the chassis via a 10 ohm resistor -- a Panasonic shown here. This is the same device Adcom used in the GFP-555.
You can use any of the ground-loop breakers on the Elliott Sound Products site, or the one which pops up in the Pass Amplifiers discussion.
The Linear Tech regulators sounded much better than the LM317/337 in the regulator shoot-out. If you are sticking with the LM's they should have 100uF on the output.
An externally hosted image should be here but it was not working when we last tested it.
The signal ground is connected to the chassis via a 10 ohm resistor -- a Panasonic shown here. This is the same device Adcom used in the GFP-555.
An externally hosted image should be here but it was not working when we last tested it.
You can use any of the ground-loop breakers on the Elliott Sound Products site, or the one which pops up in the Pass Amplifiers discussion.
The Linear Tech regulators sounded much better than the LM317/337 in the regulator shoot-out. If you are sticking with the LM's they should have 100uF on the output.
Firstly I would like to thank you for your quick responses. In a few words I will try to explain what I did and how I connected the grounds.
As I mentioned I use power supply with lm 317 lm 337 circuit with additional 1000uF on the output, the main filter capacitors are bypassed with 1uF (Wima) Polypropylene. From the power supply pcb make the grounding loop breaker with 0.1 uF and 10 ohm resistor in parallel to the chasis ground, at the same point I conect central ground from Euro Conector to the chasis (star grounding) just like you can see in the picture. What I tell you now is very important if a decision to change the potentiometer. The first big mistake when order Alps potentiometer 100 K ohm, logically I measured the old worn potentiometers but if you look closely schematic view you will see that the balance & volume potentiometer connected in parallel (both two are 100 Kohm) which means that it acts as one of the 50K ohm potentiometer. I immediately ordered a new potentiometer of 50K ohm on the hot end of the resistor conect 47 K ohms and the situation is now much better. As for the hum that is heard when the potentiometer is opened is difficult to determine whether the problem is with the grounding or something else. A few days ago I bought from Ebay HAFLER DH-200 in excellent condition and I finally decided to fix preamp. Regarding LT regulator once you have told me that they are better in any segment you thought?
As I mentioned I use power supply with lm 317 lm 337 circuit with additional 1000uF on the output, the main filter capacitors are bypassed with 1uF (Wima) Polypropylene. From the power supply pcb make the grounding loop breaker with 0.1 uF and 10 ohm resistor in parallel to the chasis ground, at the same point I conect central ground from Euro Conector to the chasis (star grounding) just like you can see in the picture. What I tell you now is very important if a decision to change the potentiometer. The first big mistake when order Alps potentiometer 100 K ohm, logically I measured the old worn potentiometers but if you look closely schematic view you will see that the balance & volume potentiometer connected in parallel (both two are 100 Kohm) which means that it acts as one of the 50K ohm potentiometer. I immediately ordered a new potentiometer of 50K ohm on the hot end of the resistor conect 47 K ohms and the situation is now much better. As for the hum that is heard when the potentiometer is opened is difficult to determine whether the problem is with the grounding or something else. A few days ago I bought from Ebay HAFLER DH-200 in excellent condition and I finally decided to fix preamp. Regarding LT regulator once you have told me that they are better in any segment you thought?
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
wally 5 Can you confirm to me that your preamp completely silent or still hear some kind of hum or buzz?
When I hear the hum only when you get closer loudspeaker very close but I think even that is not supposed.
jackinnj I plan to put the RFI filter as you put in the DH-110 that you would have been some positive hearing progress ?
Hi, phono stage has a very low hum at full volume; at normal too high listening levels you would never hear hum which is more than acceptable, when turntable is not plugged into phono jacks, at full volume get a lot of hiss, no hum or buzz. Line stage is completely quite no buzz or hum. Your work looks great hope you get it sorted.
I remember before start upgrading the preamp when (tone defeat) is switched ON there is a low hum, when turned OFF it seems to me that there was no hum. I read somewhere that it is not necessary to eliminate the tone control but it is necessary to calibrate the potentiometers (measure the half resistance of the potentiometer - knob dash must be in the middle).
Can you do check for me to be sure, when the tone defeat is ON do you hear anything?
If you are referring to my question, then no. I have ben trying to install the dh-102 pre-preamp so that I can use my Denon dl-301 mc cart. I don'y know where to solder in the mute wires and I have a significant hum now. I tried going straight to the board and bypassing the switches but I am getting no output when I do so.