Hello everyone,
I have a high-end Swiss Physics Model 5 preamplifier, which is both beautiful and great-sounding. Despite this, it has a few flaws. Since it’s my favorite preamp, I’d like to learn how to repair it and possibly improve it, as it doesn’t really have a resale market.
First off, if anyone finds the schematics, I’ll buy you a pizza.
Some modules are resin-potted specifically to prevent them from being “copied,” which brings me to my first question. Given that the modules are fairly repetitive, wouldn’t it, in theory, be possible to remove the resin with a dental drill to figure out their composition—assuming someone had nothing better to do in life? I’m just starting out, so I’m curious.
Second question: call it a thesis project, call it something else, but this preamp keeps breaking down. I don’t replace it because it sounds better than anything else. Plus, it’s gorgeous.
One issue—or maybe not an issue, but still...
After the preamp, my signal goes into professional mixing/mastering monitors, specifically the Dynaudio BM 15A. They’re active speakers without a volume knob. The problem is that I end up using the preamp at only 2 or 3% of its volume range.
For normal home listening, I’m basically moving the volume knob by just half a millimeter.
So, I was wondering: could I add a trimmer?
Something to lower the base signal level.
Since this is a high-end system, anything I add could affect the sound, so the more transparent the solution, the better.
And one more thing: since the preamp is so powerful, it has a noticeable background noise. True, lowering the signal strength should also reduce this, but generally speaking, if I’m dealing with slight hums or background noise, where should I focus to make it quieter?
I have a high-end Swiss Physics Model 5 preamplifier, which is both beautiful and great-sounding. Despite this, it has a few flaws. Since it’s my favorite preamp, I’d like to learn how to repair it and possibly improve it, as it doesn’t really have a resale market.
First off, if anyone finds the schematics, I’ll buy you a pizza.
Some modules are resin-potted specifically to prevent them from being “copied,” which brings me to my first question. Given that the modules are fairly repetitive, wouldn’t it, in theory, be possible to remove the resin with a dental drill to figure out their composition—assuming someone had nothing better to do in life? I’m just starting out, so I’m curious.
Second question: call it a thesis project, call it something else, but this preamp keeps breaking down. I don’t replace it because it sounds better than anything else. Plus, it’s gorgeous.
One issue—or maybe not an issue, but still...
After the preamp, my signal goes into professional mixing/mastering monitors, specifically the Dynaudio BM 15A. They’re active speakers without a volume knob. The problem is that I end up using the preamp at only 2 or 3% of its volume range.
For normal home listening, I’m basically moving the volume knob by just half a millimeter.
So, I was wondering: could I add a trimmer?
Something to lower the base signal level.
Since this is a high-end system, anything I add could affect the sound, so the more transparent the solution, the better.
And one more thing: since the preamp is so powerful, it has a noticeable background noise. True, lowering the signal strength should also reduce this, but generally speaking, if I’m dealing with slight hums or background noise, where should I focus to make it quieter?
I put the switch on the -10 db but the "problem" is the same.
Today i have a new problem and i would ask to you where do you looking for about the problem inside the preamp. Where the first step for check the situation?
I try to explain: the right channel don't operate anymore but if i put the switch on the preamp in MONO setting i can hear both the speaker.
Wich is the forst step for found the problem?
I repeat i'm a beginner with a looooooot of passion and patience.
Let me know and thank you
Today i have a new problem and i would ask to you where do you looking for about the problem inside the preamp. Where the first step for check the situation?
I try to explain: the right channel don't operate anymore but if i put the switch on the preamp in MONO setting i can hear both the speaker.
Wich is the forst step for found the problem?
I repeat i'm a beginner with a looooooot of passion and patience.
Let me know and thank you
It should be in the +4dB stand, this makes the input less sensitive.
You are connecting an unbalanced output to a balanced input. Each output should be connected to a speaker like this:
If your problem is not related to bad or wrong connections, I'm afraid fixing this without schematic is sheer impossible, even with a lot of passion and patience. 🙂
Probably the Preamp Siwss come out with unbalanced RCA.
Please tell me or link to me a right cable for connect with Dynaudio that i'm sure that have a balanced input. (i must choose unbalanced cable or balanced cable?)
I check and at the moment the switch is on +4 db.
I check when i choose -10 db and the volume come up.
Let me know and thank you
Please tell me or link to me a right cable for connect with Dynaudio that i'm sure that have a balanced input. (i must choose unbalanced cable or balanced cable?)
I check and at the moment the switch is on +4 db.
I check when i choose -10 db and the volume come up.
Let me know and thank you
I know that there are two kind of cable: unbalanced and balanced, in the case that the two interface have two different kind of connection (preamp Umbalanced - Dynaudio Balanced) which is the right cable to choose for connect the two device? Probably the right answer is Unblanaced and probably in the pass i choose Balanced cable. Could be this the problem?
Any cable with the schematics provided by Netlist will do the job: search XLR to rca cable on your favourite shopping site.
oook so the problem probably don't come from the cable because i choose a normal XLR to rca cable. Now if you are agree i must understand if:
Are you agree? and if you are not agree please write to me some adviace.,
Thank you
- or inside the preamp there are some trim for low the output gain
- or inside the DYNADUIO BM15A there are some trim for low the input gain
Are you agree? and if you are not agree please write to me some adviace.,
Thank you
Probably. Personally, I'd try to find a solvent or acid that'll remove the resin. It'll be less messy and there's less chance of damaging the circuit inside.
Tom
OK, you already have the cable and it did not work. Sorry, but I do not have any advice other than that of open the preamp and, maybe, follow the advice of Tom above. Unfortunately it's not so easy to work on modules covered by resin.
A word of caution, this is a precious preamp and not suited as a beginners project.
Re opening the modules and removal of the potting compound (post 1 and 11) see
I do not remember it was possible or easier to remove the resin with heat appied.
I did it by mechanical means.
If you find a solvent which does the job components will not be unaffected.
Re opening the modules and removal of the potting compound (post 1 and 11) see
I do not remember it was possible or easier to remove the resin with heat appied.
I did it by mechanical means.
If you find a solvent which does the job components will not be unaffected.