Hi Fabian,
I might have someone interested. Please PM me the price and list of components.
Thanks
Do
My build in the new chassis is almost complete. Awaiting binding posts and RCA jacks from WBT and Furutech (got an amazing deal on them I couldn't refuse).
See latest build pictures here:
Amplificateur FC-100
Missing from the pictures are my Mirand Audio SSR speaker protection which should be added sometime this week.
Thanks
Do
See latest build pictures here:
Amplificateur FC-100
Missing from the pictures are my Mirand Audio SSR speaker protection which should be added sometime this week.
Thanks
Do
Nice build pinnocchio
I've read your Amplificateur FC-100 posts - if I'm not wrong, it looks like the back-end PS (on the FC-100 boards) is not used and you have a separate PS feeding the amp.
May I ask what back-end PS design you have used and why you didn't use the FC-100 PS on the board?
I have the original FC-100 and (to free up some space) am thinking about carefully(!) cutting the FC-100 boards to mount the cut back-end PS elsewhere in the amp as you have done, but may follow your design if it can avoid cutting the board.
Thanks
I've read your Amplificateur FC-100 posts - if I'm not wrong, it looks like the back-end PS (on the FC-100 boards) is not used and you have a separate PS feeding the amp.
May I ask what back-end PS design you have used and why you didn't use the FC-100 PS on the board?
I have the original FC-100 and (to free up some space) am thinking about carefully(!) cutting the FC-100 boards to mount the cut back-end PS elsewhere in the amp as you have done, but may follow your design if it can avoid cutting the board.
Thanks
Hi Chris,
Could you tell what max. toroidal transformer power rating Rudi's SPO can handle, considering added psu capacitance? Perhaps 1.6-2KVA and 200mF?
Thanks.
I do not see any reason why not to use the PCBs backend-PSU. 
There are various ways to connect the backend PSU to your transformer:
Use the MUR8x0 rectifying diodes (which is the default), use an (one) "off-board bridge-rectifier", use two "off-board bridge-rectifiers",...
I have attached a picture of what I call a "bridge-rectifier"
In any case: the backend-PSU shall supply the needed current to the output-transistors as fast as possible, and this can be done best, if the power caps are located close to the transistors.
So my recommendation is not to use an external backend-PSU!
Best regards - Rudi_Ratlos
There are various ways to connect the backend PSU to your transformer:
Use the MUR8x0 rectifying diodes (which is the default), use an (one) "off-board bridge-rectifier", use two "off-board bridge-rectifiers",...
I have attached a picture of what I call a "bridge-rectifier"
In any case: the backend-PSU shall supply the needed current to the output-transistors as fast as possible, and this can be done best, if the power caps are located close to the transistors.
So my recommendation is not to use an external backend-PSU!
Best regards - Rudi_Ratlos
Attachments
The reason I did this was to use a dual bridge topology where you can isolate the AC ground completely from the circuit, something that cannot be done using single bridge Also, add a CRC filter in between cap banks and use bigger 4 pin caps I had in hand. Rudi's implementation is perfectly good and for most, if not all builds it will be doing a great job. I have bought the PSU PCB from the thread below
http://www.diyaudio.com/forums/group-buys/301682-crc-power-supply-class-amplifier.html
But as I have said, it is really not necessary to do so.
Thanks Wineds!
I have this weird issue with one of my DACs connected to this amplifier. Whatever preamp I used doesn't change anything...
This DAC when used with the FC-100 outputs a very high frequency pitch on the tweeters only. It is not super loud but when listening to music it gets tiring after a few songs. My three other DACs don't create this issue. When the amplifier is fired up without a signal it is silent, when input shorted it is silent and when connected to other sources it is silent...
I'm wondering if it is picking up some sort of digital artifact from the DAC...? Weird because the same DAC connected to any other amplifiers is totally silent, dead silent!
Is the output of the DAC making the FE of the FC-100 oscillate?
Any feedback would help.
Thanks
Do
This DAC when used with the FC-100 outputs a very high frequency pitch on the tweeters only. It is not super loud but when listening to music it gets tiring after a few songs. My three other DACs don't create this issue. When the amplifier is fired up without a signal it is silent, when input shorted it is silent and when connected to other sources it is silent...
I'm wondering if it is picking up some sort of digital artifact from the DAC...? Weird because the same DAC connected to any other amplifiers is totally silent, dead silent!
Is the output of the DAC making the FE of the FC-100 oscillate?
Any feedback would help.
Thanks
Do
Hi Do, mine is completed and I get total silence. I have tried Opus, Buffalo, and a 8 X TDA1543 dac I was given and repaired recently. All were fine, no noise or high pitch. Is this dac usb? It may be the usb is picking up noise from the PSU? I know you say it works with other amps, but it could be the pc you are using or something else. If possible I would try this dac with an spdif input and see if it goes away.
Hi Luke,
I'm actually using very low noise PSUs (AMB Sigma 22 and Sigma 11) for the Mirand DAC and the Pi3 is also using a very low noise linear PSU (Sigma 11). Network to the Pi3 is also using an Pro-Tek5 Ethernet Protection module. I will check for oscillation with the scope shortly and with the help of my friend, verify the input stage filter.
Thanks
Do
I'm actually using very low noise PSUs (AMB Sigma 22 and Sigma 11) for the Mirand DAC and the Pi3 is also using a very low noise linear PSU (Sigma 11). Network to the Pi3 is also using an Pro-Tek5 Ethernet Protection module. I will check for oscillation with the scope shortly and with the help of my friend, verify the input stage filter.
Thanks
Do
Hi Do, have you got matched transistors as per the build guide? I believe CFP is quite prone to instability if the N and P drivers are not matched, I think it applies to output stage too. I am not an expert, but I recall reading this somewhere. I suspect your amp is on the edge of stability and maybe dangerous for your speakers. try and gain access to an oscilloscope and signal generator and make a dummy load if you don't have one. Also, do you have a zobel circuit on the output? Hopefully someone with a bit more experience can chime in here.
Hi Luke,
I have an oscilloscope that I will use to test the amplifier's IS and OS. All transistors were matched (bought part of the GB) and JFets by a very reliable source on this forum. The offset is solid at 1.4mV on both channels. I was experiencing this phenomena on both channels on a fully dual mono configuration for amplifier and preamplifier so both amplifiers would have had to have the same issue, which is weird...
This was only happening with a specific DAC source but all other sources including other DACs didn't make the high pitch. As soon as I have removed the long interconnects it fixed the high pitch sound issue, the amplifier is silent.
Don't have a zobel on the output and I might add one. I have an SSR speaker protection circuit from Mirand on the output and it did save my life (more like my speakers life) when one of the PSU fuse got blown, leaving the full DC rail on the speaker output...
I since then replaced those fast blow fuses for slow blow fuses just because the inrush on startup using low ESR caps (the ones local on the OS).
Ciao!
Do
I have an oscilloscope that I will use to test the amplifier's IS and OS. All transistors were matched (bought part of the GB) and JFets by a very reliable source on this forum. The offset is solid at 1.4mV on both channels. I was experiencing this phenomena on both channels on a fully dual mono configuration for amplifier and preamplifier so both amplifiers would have had to have the same issue, which is weird...
This was only happening with a specific DAC source but all other sources including other DACs didn't make the high pitch. As soon as I have removed the long interconnects it fixed the high pitch sound issue, the amplifier is silent.
Don't have a zobel on the output and I might add one. I have an SSR speaker protection circuit from Mirand on the output and it did save my life (more like my speakers life) when one of the PSU fuse got blown, leaving the full DC rail on the speaker output...
I since then replaced those fast blow fuses for slow blow fuses just because the inrush on startup using low ESR caps (the ones local on the OS).
Ciao!
Do
Hi Do,
You really do need a zobel on the output! What possessed you to omit this necessary part of this amplifier??
If cable capacitance on the input causes this to occur, you should have an RF filter on the input. Normally these are also part of any amplifier design. Proper ones anyway.
The DAC. Is it an NOS type? If so, you desperately need to install the 7th order output filters! Early generation CD players all used them, for a bloody good reason. The entire reason we went to oversampling to begin with was to avoid using such a nasty filter. Otherwise you will have 44.1 KHz signals in your audio system, and that can be pretty hard on output zobels and amplifiers in general. If you can get a 'scope, use it all the way back to the DAC. Please tell me that you are not using an NOS DAC.
-Chris
You really do need a zobel on the output! What possessed you to omit this necessary part of this amplifier??
If cable capacitance on the input causes this to occur, you should have an RF filter on the input. Normally these are also part of any amplifier design. Proper ones anyway.
The DAC. Is it an NOS type? If so, you desperately need to install the 7th order output filters! Early generation CD players all used them, for a bloody good reason. The entire reason we went to oversampling to begin with was to avoid using such a nasty filter. Otherwise you will have 44.1 KHz signals in your audio system, and that can be pretty hard on output zobels and amplifiers in general. If you can get a 'scope, use it all the way back to the DAC. Please tell me that you are not using an NOS DAC.
-Chris
Actually, looking at the schematics, the Zobel is on the PCB itself (R8 & C2). Some amplifiers like Fab's USSA 5 does not require a Zobel and is extremely stable without it. But I do have very good speaker protection and love to play with "fire"... LOL!
Not using a NOS DAC, I'm using one based on AK4490 with a very well designed output stage, totally silent actually.
I will definitely test with the scope to make sure everything is ok.
Ciao!
Do
You are 100% right on this, design is everything.
All the best and thanks for your suggestions. I will definitely put on a dummy load and test it with a signal generator and scope.
Ciao!
Do
ok, I figured out what was my issue... The ground of my speaker protection was touching the metal standoff which is tied to the chassis... This seems to have blown off all my NJL0302 and NJL0281...
Is there anyone wanting to sell his transistor kit (the matched kit from this GB)? I would be buying it asap.
Thanks
Do
Is there anyone wanting to sell his transistor kit (the matched kit from this GB)? I would be buying it asap.
Thanks
Do