Yes, I do agree Andrew, but it really takes time to do so haha.. At the moment, I am waiting for a new LM318N chip and a new trafo. I have ordered a dual trafo, AMPLIMO, rated 225VA 2x115VAC primary and 2x24VAC secondary. I believe my Talema trafo rated at 230VAC primary and 2x25VAC secondary is the reason why the LM3886 chips become so hot.
Meanwhile I am reading the whole thread starting from the first page in order to get better knowledge of myrev.c
Meanwhile I am reading the whole thread starting from the first page in order to get better knowledge of myrev.c
Thanks, sounds interesting. We'll be following Kreisky's progress and reports. After the recent recovery of the v1.3s, the LF01s were put back in. They still sound smooth, clean and stately
I have mounted LF07 about ten days ago... Then I listened much music for a week. After a week I mounted back the LM318 and
… the difference is remarkable! With lm318 the stage is closer to speaker, less deep and less wide. Overall, in my system, with LF07 My-ref C has an improved spatial definition and wider stage. The position of each instrument is more precise in the space. There is something more open in the stage, the sound is more articulate and defined, also I feel like if the music has more “energy”.
I am not so good in explain sound qualities in english but this is a very nice hi-end upgrade
Thanks Siva !
Thanks for the report. Glad you are happy with the results. No problem understanding your review,Marco, thanks for the praise and good to hear that you like it!
Bob - the LF07 uses essentially the same principle as the LF01 that you have, but with a push-pull Class-A output stage implemented with SMD parts in a smaller footprint. The intent is to obtain similar sonics as the LF01, but with lower quiescent current of the order of 8-10 mA. The latest LF07 (which Marco and I both use in a Rev C) uses micro-MELF thin-film resistors, which should have linearity and noise performance comparable to high-quality through-hole metal-films.
Bob - the LF07 uses essentially the same principle as the LF01 that you have, but with a push-pull Class-A output stage implemented with SMD parts in a smaller footprint. The intent is to obtain similar sonics as the LF01, but with lower quiescent current of the order of 8-10 mA. The latest LF07 (which Marco and I both use in a Rev C) uses micro-MELF thin-film resistors, which should have linearity and noise performance comparable to high-quality through-hole metal-films.
If I want to put a second set of inputs on the back panel of my RevC and have a toggle switch to select the input, would I use a DPDT and leave both input grounds always connected? Or a 3PDT and switch the input grounds as well?
Am I going to risk introducing noise or hum with that threaded metal part of the switch contacting the case? My 2 sources will be a self-powered USB DAC and a wall-powered phono preamp.
Am I going to risk introducing noise or hum with that threaded metal part of the switch contacting the case? My 2 sources will be a self-powered USB DAC and a wall-powered phono preamp.
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The better location for source selection is at the pre-amp, if it has additional aux-inputs. However, you can use a relay-switched selector within the MyRef case, or even a DPDT switch as you mentioned (with shielded cabling from the RCAs and to the pots).
Well, that's my problem...my phono preamp is currently one of those cigarette box-sized commercial units, and has no controls or extra inputs. I have to have this done before Christmas company comes, and can't really build a DIY preamp before then as I'm short on time & funds this month as I am every December.
But it's better to use a DPDT switch and leave both input grounds always connected than to use a 3PDT and switch the grounds as well?
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IMHO, 3PDT would be much better. That way you'll avoid any possible ground loop which may be formed by/via the unused input(s).
But perhaps you'd better make sure to always "terminate" all the inputs by connecting a suitable (let' say, 10K) resistor across them when unused.
To avoid possible DC buildup across different grounds, which may produce "bumps" when switching (and even bigger problems should the DC difference among the different grounds be large enough) it may be a good idea to keep the grounds connected via a (relatively) large resistor (say, 100K) when unused. That should be large enough to "break" the possible ground loops, yet small enough to keep the different GNDs at the same voltage.
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Hmmm. I think I may just stick with one set of inputs for now if I'm going to risk causing hum problems with the toggle switch. I'll just swap cables when I want to change sources till I get around to building a nice preamp with multiple inputs, built-in DAC, etc.
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All stereo amplifiers suffer the same problem.
Two channels coming in from a commoned audio ground in the Source will have a LOOP in the input circuit.
This has nothing to do with switching inputs.
That's why clever switching cannot solve the problem.
A figure of 8 dual coax with the coax screens in electrical contact could solve this input loop area problem, but I have not seen it nor the connector plugs/sockets that could accommodate that special cable.
Monoblock amplifiers avoid the problem BECAUSE they are single channel input.
Two channels coming in from a commoned audio ground in the Source will have a LOOP in the input circuit.
This has nothing to do with switching inputs.
That's why clever switching cannot solve the problem.
A figure of 8 dual coax with the coax screens in electrical contact could solve this input loop area problem, but I have not seen it nor the connector plugs/sockets that could accommodate that special cable.
Monoblock amplifiers avoid the problem BECAUSE they are single channel input.
Hmmm I see..what if I were to make the back panel where all the connectors are out of wood? Does that solve anything?
indeed that's one source of ground loops (almost unavoidable, unless using transformer-coupled inputs and/or outputs).
But it's not the only one, and not the one I was thinking of.
In many cases there may be ground loops between different devices through the safety "earth"/ground connections (and signal cable ground).
Breaking the signal gnd connection with unused devices will at least reduce the chance to have such kind of (avoidable) ground loops.
Of course, this way the loop can be avoided only if it occurs between two "sources". If it occurs between a (selected) source and the (pre)amplifier a different solution must be adopted...
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Hi guys,
can I ask you something?
I assembled a My_ref two months ago and I like it very much... It sounds very good and everything seems ok, but I hear a "pop" (sometimes loud) when I turn off the amp...
Maybe someone had the same problem and so, how did you solve it?
Thank you very much!
P.S. Could I try a switch spark-suppression capacitor? Could it be useful?
can I ask you something?
I assembled a My_ref two months ago and I like it very much... It sounds very good and everything seems ok, but I hear a "pop" (sometimes loud) when I turn off the amp...
Maybe someone had the same problem and so, how did you solve it?
Thank you very much!
P.S. Could I try a switch spark-suppression capacitor? Could it be useful?
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