Shown on the images below is the "competitor / rival" of my FC-100.
It is a SYMASYM based upon my "TO264- SYMASYM" - PCBs.
It has a pair of matched MPSA18 transistors on the input, uses 2 pairs of matched NJW0281G/NJW0302G on the output,
has a CAP-Multiplier on-board to provide a stable supply voltage for the frontend, ...
This SYMASYM is powered by a 2 x 25 VAC / 300VA transformator and the DX PSU.
The attenuation is done by the "Lightspeed Attenuator", which is controlled by a BOURNS motorized 100K potentiometer.
The attenuation can be controlled remotely.
The SYMASYM is a Christmas present for my brother, and I have done my very best to give it a good sound.
I have invited several friends in the next week, and I will perform a "shootout" between the FC-100 and this SYMASYM then.
I will keep you informed.
Best regards - Rudi
It is a SYMASYM based upon my "TO264- SYMASYM" - PCBs.
It has a pair of matched MPSA18 transistors on the input, uses 2 pairs of matched NJW0281G/NJW0302G on the output,
has a CAP-Multiplier on-board to provide a stable supply voltage for the frontend, ...
This SYMASYM is powered by a 2 x 25 VAC / 300VA transformator and the DX PSU.
The attenuation is done by the "Lightspeed Attenuator", which is controlled by a BOURNS motorized 100K potentiometer.
The attenuation can be controlled remotely.
The SYMASYM is a Christmas present for my brother, and I have done my very best to give it a good sound.
I have invited several friends in the next week, and I will perform a "shootout" between the FC-100 and this SYMASYM then.
I will keep you informed.
Best regards - Rudi
Attachments
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Adrian:
I am currently doing a group-buy for the German DIYers. The group-buy is already closed, but I think that I will have 1 set of FC-100 PCBs
and "hard-to-get" components left.
The set consists of PCBs, 4 x 34VAC transformer, 2SK170BL pairs, authentic Toshiba 2SA1360/SC3423,
MJE15034/35, NJLs, MPC74 emitter resistors, ...
All transistors are closely matched according to Mihai's specifications. For example: the 2SK170BL have an IDss > 9mA and are
"VGS - matched" at ID 6.2mA (best that I could).
I can tell you tomorrow, after I have packed all the parcels for the Germans.
I will never do a 3rd round of group-buy for the FC-100 as is, even though the FC-100 is the most-beautiful DIY-AMP, I have ever listened to.
I congratulate all of you, who have their DIY-kits and will build it. Do it carefully, please: this AMP is being worth your carefulness.
The reason for never offering a 3rd round: it is extremely difficult to order/buy NJL0281DG/NJL0302DG !
MOUSER will offer them again in October 2013 (!), FARNELL, DIGIKEY, RSONLINE, ..., do not have them on stock, ...
I was really happy to finally find a supplier of the NJLs (150 of each) for the German group-buy!
Moreover: if you take a look at the FC-100 technical threads, you will notice that the build of the FC-100 is not always "DIY foolproof"
due to some anomalies (maybe) of the integrated ThermalTrak diodes.
It is the backend of the FC-100 that is causing me headaches.
The FC-100 frontend is IMHO above any reproach!
I will ask Mihai (and my favourite German DIY mentor), if he will assist in a re-design of the backend, in something like Groner-triple,
like KRELL did, ... But it will take quite a while, before I will be able to present you the FC-100 MKII - if ever.
Best regards - Rudi_Ratlos
I am currently doing a group-buy for the German DIYers. The group-buy is already closed, but I think that I will have 1 set of FC-100 PCBs
and "hard-to-get" components left.
The set consists of PCBs, 4 x 34VAC transformer, 2SK170BL pairs, authentic Toshiba 2SA1360/SC3423,
MJE15034/35, NJLs, MPC74 emitter resistors, ...
All transistors are closely matched according to Mihai's specifications. For example: the 2SK170BL have an IDss > 9mA and are
"VGS - matched" at ID 6.2mA (best that I could).
I can tell you tomorrow, after I have packed all the parcels for the Germans.
I will never do a 3rd round of group-buy for the FC-100 as is, even though the FC-100 is the most-beautiful DIY-AMP, I have ever listened to.
I congratulate all of you, who have their DIY-kits and will build it. Do it carefully, please: this AMP is being worth your carefulness.
The reason for never offering a 3rd round: it is extremely difficult to order/buy NJL0281DG/NJL0302DG !
MOUSER will offer them again in October 2013 (!), FARNELL, DIGIKEY, RSONLINE, ..., do not have them on stock, ...
I was really happy to finally find a supplier of the NJLs (150 of each) for the German group-buy!
Moreover: if you take a look at the FC-100 technical threads, you will notice that the build of the FC-100 is not always "DIY foolproof"
due to some anomalies (maybe) of the integrated ThermalTrak diodes.
It is the backend of the FC-100 that is causing me headaches.
The FC-100 frontend is IMHO above any reproach!
I will ask Mihai (and my favourite German DIY mentor), if he will assist in a re-design of the backend, in something like Groner-triple,
like KRELL did, ... But it will take quite a while, before I will be able to present you the FC-100 MKII - if ever.
Best regards - Rudi_Ratlos
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Whoowh!
I received a feedback from Mihai (Mihai: "Enjoy your holidays! Have a very nice time and do not break any of your bones!"),
in which he signalized to provide me an alternative to the "NJL0281/NJL0302" (very hard, near to impossible to get these
transistors nowadays) backend.
I am looking forward to his proposal.
Best regards - Rudi_Ratlos
I received a feedback from Mihai (Mihai: "Enjoy your holidays! Have a very nice time and do not break any of your bones!"),
in which he signalized to provide me an alternative to the "NJL0281/NJL0302" (very hard, near to impossible to get these
transistors nowadays) backend.
I am looking forward to his proposal.
Best regards - Rudi_Ratlos
Sound Comparison
I have just returned from my friend Christian, who invited me to do the "sound-comparison" between the FC-100 and the SYMASYM at his home.
The reason for not performing this comparison at my home was: my speakers (Behringer 2031B Truth) "do not sound", are not able to reproduce a stage.
Here are the 2 competitors:
On the right side on the floor, with the ALU front-plate: the SYMASYM.
Details of the SYMASYM: one transformer, 2x25VAC / 300VA, one PSU with 20.000µF per power rail, each channel having 2 pairs of NJW0281/NJW0302 as output transistors.
As attenuator I use the George Stantscheff's "Lightspeed-Attenuator".
On the left side: the FC-100 (you know it for sure), having two transformers, 2 x 25 VAC /160VA each, the backend power-supply of each channel being "backed-up" by 20.000µF per power-rail. As attenuator I use a PGA2311-based attenuator developped by the German Stefan Dreyer.
A pair of Infinity Kappa 400 (6 Ohm impedance) serves as speakers.
We listened to 2 CDs: "George Benson - Weekend in L.A." and "Depeche Mode - Remixes 81-11"
First the SYMASYM:
Christian was very impressed by the SYMASYM. It plays very "lively", very dynamically and offers at lot of soul.
The sound of the SYMASYM immediately reminded him of the old-school NAD3020 with a lot of power.
Then the FC-100:
First: listening to George Benson.
His first remark: "Whoowh". Ultra-fast, perfect resolution (you can hear George Benson's voice 50 cm above the guitar that he is playing),
very wide stage,really astounding, "leave this AMP here".
Then: listening to Depeche Mode.
Christian played a track with very deep going bass, as low as 60-70 Hz.
At these frequencies the FC-100 showed some kind of "weakness" and was not able to reproduce these frequencies "in a controlled, superior way".
My FC-100 does not "play" these frequencies; it "pushes / shoves" them. It is not bad, but could be done better.
Christian then took me into his living-room, where we listened to the same Depeche Mode track, this time playing on his AYRE K-5xe / V-5xe
and a pair of B&W 801D. I noticed the difference.
I asked him: "If I would give your AYRE - amplifier 95 of 100 possible points for sound reproduction: how would you rate the SYMASYM / the FC-100?"
His answer: "I would give 80 points to the SYMASYM. I would give 90 points to the FC-100, if it could reproduce the very low frequencies better.
It is perfect to play Jazz and mainstream POP.
Knowing about its deep-bass weakness, I give it 88 points."
This has been the result of the "shoot-out" - and I agree.
How can the FC-100's weakness to reproduce very low frequencies be improved? Has it to do with my specific build?
Best regards - Rudi_Ratlos
I have just returned from my friend Christian, who invited me to do the "sound-comparison" between the FC-100 and the SYMASYM at his home.
The reason for not performing this comparison at my home was: my speakers (Behringer 2031B Truth) "do not sound", are not able to reproduce a stage.
Here are the 2 competitors:
On the right side on the floor, with the ALU front-plate: the SYMASYM.
Details of the SYMASYM: one transformer, 2x25VAC / 300VA, one PSU with 20.000µF per power rail, each channel having 2 pairs of NJW0281/NJW0302 as output transistors.
As attenuator I use the George Stantscheff's "Lightspeed-Attenuator".
On the left side: the FC-100 (you know it for sure), having two transformers, 2 x 25 VAC /160VA each, the backend power-supply of each channel being "backed-up" by 20.000µF per power-rail. As attenuator I use a PGA2311-based attenuator developped by the German Stefan Dreyer.
A pair of Infinity Kappa 400 (6 Ohm impedance) serves as speakers.
We listened to 2 CDs: "George Benson - Weekend in L.A." and "Depeche Mode - Remixes 81-11"
First the SYMASYM:
Christian was very impressed by the SYMASYM. It plays very "lively", very dynamically and offers at lot of soul.
The sound of the SYMASYM immediately reminded him of the old-school NAD3020 with a lot of power.
Then the FC-100:
First: listening to George Benson.
His first remark: "Whoowh". Ultra-fast, perfect resolution (you can hear George Benson's voice 50 cm above the guitar that he is playing),
very wide stage,really astounding, "leave this AMP here".
Then: listening to Depeche Mode.
Christian played a track with very deep going bass, as low as 60-70 Hz.
At these frequencies the FC-100 showed some kind of "weakness" and was not able to reproduce these frequencies "in a controlled, superior way".
My FC-100 does not "play" these frequencies; it "pushes / shoves" them. It is not bad, but could be done better.
Christian then took me into his living-room, where we listened to the same Depeche Mode track, this time playing on his AYRE K-5xe / V-5xe
and a pair of B&W 801D. I noticed the difference.
I asked him: "If I would give your AYRE - amplifier 95 of 100 possible points for sound reproduction: how would you rate the SYMASYM / the FC-100?"
His answer: "I would give 80 points to the SYMASYM. I would give 90 points to the FC-100, if it could reproduce the very low frequencies better.
It is perfect to play Jazz and mainstream POP.
Knowing about its deep-bass weakness, I give it 88 points."
This has been the result of the "shoot-out" - and I agree.
How can the FC-100's weakness to reproduce very low frequencies be improved? Has it to do with my specific build?
Best regards - Rudi_Ratlos
Attachments
Last edited:
Interesting.
Two things come to my mind regarding bass performance.
First, the psu, it needs to be bigger and stiffer. Double transformers size and capacitors bank. I wouldn't do a CLC, though, because is a class AB.
Second check your amp for some wrong value in the networks that define frequency response, maybe you did some mistake.
Third, you should have tried the amp in your friend'd main system with the Ayre preamp. Apples to apples.
Note that the Ayre is a two stage amp without global feedback.
Two things come to my mind regarding bass performance.
First, the psu, it needs to be bigger and stiffer. Double transformers size and capacitors bank. I wouldn't do a CLC, though, because is a class AB.
Second check your amp for some wrong value in the networks that define frequency response, maybe you did some mistake.
Third, you should have tried the amp in your friend'd main system with the Ayre preamp. Apples to apples.
Note that the Ayre is a two stage amp without global feedback.
Hi Rudi,
The PGA-2311 is most likely your bottleneck here... It is good but nothing to compare to a good stepped attenuator or high quality pot. I have tried many itterations of PGA-2310 and 2311 and the 2310 is a little better because of the 15V supply it has better swing but it is still a PGA... I would retry this with a better attenuator and it will most likely give justice to the FC-100
Ciao!
Do
The PGA-2311 is most likely your bottleneck here... It is good but nothing to compare to a good stepped attenuator or high quality pot. I have tried many itterations of PGA-2310 and 2311 and the 2310 is a little better because of the 15V supply it has better swing but it is still a PGA... I would retry this with a better attenuator and it will most likely give justice to the FC-100
Ciao!
Do
Thank you Rudi for the interesting test.
I would do the test in a chain where i only change the power amps. The volume control should be the same too.
I use 400VA toroid and added some mor capacitances for my RFI-FC100 and comparing it to my other DIY amps i don't miss the bass, it has a well controlled bass and goes deep in my system.
Thanks again for your findings.
Best Regards,
zsaudio
I would do the test in a chain where i only change the power amps. The volume control should be the same too.
I use 400VA toroid and added some mor capacitances for my RFI-FC100 and comparing it to my other DIY amps i don't miss the bass, it has a well controlled bass and goes deep in my system.
Thanks again for your findings.
Best Regards,
zsaudio
Gentlemen,
thank you for your feedback.
When I drove home yesterday night, I had the same impression that some of you expressed in their feedback: my transformers (2 x 160 VAC)
and reservoir-caps (20.000µF per rail) are to small for this kind of music (frequencies < 100 Hz).
I can easily replace the digital PGA2311 attenuator by an ALPS Velvet motorized potentiometer.
But the most important: I will not be able to notice any sonic change, unless I will connect a pair of "adequate" speakers to the FC-100.
The pair of Behringer 2031B Truth that I am currently using, conceil too much of sound-information.
So: this will be my next project: a pair of new speakers (DIY-type?), and then I will "upgrade" my FC-100.
Best regards - Rudi
thank you for your feedback.
When I drove home yesterday night, I had the same impression that some of you expressed in their feedback: my transformers (2 x 160 VAC)
and reservoir-caps (20.000µF per rail) are to small for this kind of music (frequencies < 100 Hz).
I can easily replace the digital PGA2311 attenuator by an ALPS Velvet motorized potentiometer.
But the most important: I will not be able to notice any sonic change, unless I will connect a pair of "adequate" speakers to the FC-100.
The pair of Behringer 2031B Truth that I am currently using, conceil too much of sound-information.
So: this will be my next project: a pair of new speakers (DIY-type?), and then I will "upgrade" my FC-100.
Best regards - Rudi
Interesting results. What kind of power capacitors are you using? My fc100 has no problem playing low frequencies and having Nikicon KG Gold Tune capacitors and two 300VA R-Core trafos
Rudi,
could you tell me please if the schematic found in build manual FC-100_Eng_V1 is the latest one ?
As i was unfortunate to buy only a part of the entire kit (only pcb's) i will start hunting/collecting the other parts and i need to know the exact parts/values.
Apart those hard to find transistors there are some special/boutique parts recommended ?
I have the emitter resistors (o.1R) only for one channel. Would be a problem to buy 0.12R for the other channel as they are easy to find on ebay ?
Thanks !
Adrian
could you tell me please if the schematic found in build manual FC-100_Eng_V1 is the latest one ?
As i was unfortunate to buy only a part of the entire kit (only pcb's) i will start hunting/collecting the other parts and i need to know the exact parts/values.
Apart those hard to find transistors there are some special/boutique parts recommended ?
I have the emitter resistors (o.1R) only for one channel. Would be a problem to buy 0.12R for the other channel as they are easy to find on ebay ?
Thanks !
Adrian
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