Roender's FC-100 Rev.1 Group-Buy - Page 47 - diyAudio
Go Back   Home > Forums > Commercial Sector > Group Buys
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Group Buys Members group buys

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 19th November 2012, 11:12 AM   #461
diyAudio Member
Rudi_Ratlos's Avatar
Join Date: Jun 2009
Location: Hamburg / Germany
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
Attached Images
File Type: jpg SIM 001.jpg (375.3 KB, 691 views)
File Type: jpg SIM 007.jpg (468.8 KB, 601 views)

Last edited by Rudi_Ratlos; 19th November 2012 at 11:14 AM.
  Reply With Quote
Old 19th November 2012, 03:44 PM   #462
evette is offline evette  Canada
diyAudio Member
Join Date: Jun 2006
Send a message via Yahoo to evette
Looks great Rudi, Evette
  Reply With Quote
Old 19th November 2012, 06:49 PM   #463
lucylu is offline lucylu  England
diyAudio Member
Join Date: Jun 2008
Location: England
Default Parts

Hello Rudi Do you have any of the shunt transformers 4 x 34 vac left also 2sk170bl matched pairs available thanks regards john
  Reply With Quote
Old 19th November 2012, 07:50 PM   #464
diyAudio Member
Rudi_Ratlos's Avatar
Join Date: Jun 2009
Location: Hamburg / Germany
Yes I do. I will send you an EMail tomorrow.
Best regards - Rudi
  Reply With Quote
Old 20th November 2012, 08:24 PM   #465
atupi is offline atupi  Romania
diyAudio Member
Join Date: Oct 2010
Location: Bucharest
Hi Rudi,

any chance to have some extra pcb's left?

  Reply With Quote
Old 21st November 2012, 09:02 AM   #466
diyAudio Member
Rudi_Ratlos's Avatar
Join Date: Jun 2009
Location: Hamburg / Germany

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

Last edited by Rudi_Ratlos; 21st November 2012 at 09:04 AM.
  Reply With Quote
Old 21st November 2012, 11:32 AM   #467
Telstar is offline Telstar  Italy
diyAudio Member
Join Date: Dec 2007
Location: Italy
You dont have to do a full kilt for the next GB, just the PCBs and whatever you have left.
I know the NJL are a PITA to match, and this before the diode issue.
"The total harmonic distortion is not a measure of the degree of distastefulness to the listener and it is recommended that its use should be discontinued." D. Masa, 1938
  Reply With Quote
Old 21st November 2012, 11:48 AM   #468
atupi is offline atupi  Romania
diyAudio Member
Join Date: Oct 2010
Location: Bucharest
Thanks Rudi ! I'm looking forward to be part of this beautiful project.

  Reply With Quote
Old 22nd November 2012, 05:26 PM   #469
diyAudio Member
Rudi_Ratlos's Avatar
Join Date: Jun 2009
Location: Hamburg / Germany

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
  Reply With Quote
Old 29th November 2012, 09:48 PM   #470
diyAudio Member
Rudi_Ratlos's Avatar
Join Date: Jun 2009
Location: Hamburg / Germany
Default 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:

Click the image to open in full size.

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 20.000F 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 20.000F 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
Attached Images
File Type: jpg competitors.jpg (215.5 KB, 341 views)

Last edited by Rudi_Ratlos; 29th November 2012 at 09:52 PM.
  Reply With Quote


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Roender's FC-100 prototype and builder's thread Rudi_Ratlos Solid State 1005 8th March 2017 05:34 AM
Sanyo/B&O Icepower 200AC Rev.D, schematic about rev. engin., not complete finished tiefbassuebertr Class D 47 22nd January 2017 04:46 PM
Tea-Bag's IXYS Depletion Mosfet Group and SemiSouth R100 JFET group buy. Tea-Bag Group Buys 330 20th May 2013 01:03 PM
Online vendors for Panasonic FC 1000/100 caps? analog_sa Parts 2 14th February 2007 02:19 AM

New To Site? Need Help?

All times are GMT. The time now is 09:39 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2