1176 in 51x/500 format, or 51X-F76 Build Support Thread

[Igor]

Yes, at 2nd package. You told you're in hurry with the comps, so, we shipped all possible stuff asap, and the rest for a week later.

 

[kante1603]

So I finally got (most of ) the parts here and will start assembly.
And here's my first question:
C3 and C4 on the motherboard are specified at 200pf in both bom and schematics.I'm not able to find them in igor's baggies.The closest to source from here is either both at 180 or 220pf as styrenes or silver mica.If nothing else works I must parallel 2 x 100pf...an ugly solution.
Any recommendations on them?

Thank you in advance,

Udo.

Edit:Found 4 wima caps in parcel number three at 220pf-will they work? (4 pieces because I have two kits here).

 

[Igor]

220pf 5% were supplied in baggies, IIRC.
These caps can be in 180pf - 220pf range but should have close (5% is ok) values.
As well, a parallel trick with 2x100 pf styrenes should work fine.

 

[kante1603]

220pf 5% were supplied in baggies, IIRC.
These caps can be in 180pf - 220pf range but should have close (5% is ok) values.
As well, a parallel trick with 2x100 pf styrenes should work fine.

Thanks Igor.
Which baggies do you mean,the one in my third parcel I guess since there are 4 pieces of Wima at 220 pf/5%/100v.
i was just wondering since on all the pics i have seen (incl. yours) there were styrenes in this positions.
Will take the wimas then.

Cheers,

Udo.

 

[Igor]

We used both styrenes and Wimas in our builds. I cannot notice any sound differencies.
Same about measurement - I check every unit's distortion on analyzer. 220pf 5% will work fine. IIRC we used FKP type Wimas.

 

[kante1603]

Hello everybody,

while reading through this thread again I found that quite a few of you had trouble with Igor's input amps.Still nobody seems to have found what the issue is except our friend chunger who swapped all transistors out step by step until it worked.Also one can read here that the bd139 could be suspects.
So before building I started measuring some parts including these-and was surprised: While one reads a hfe of 52 the other has a hfe of way over 100!I know this is within the specs,but..........
Could this be the point to look at and if so should we match them a "little" closer?
I ordered a bunch of 20 now,they're pretty cheap and try to find some better matching pairs.

Anyway,did anybody of you ever solve this issue and could post a bit about it?

It would be highly appreciated!

Cheers and have fun with your builds,

Udo.

 

[qmp audio]

Anyway,did anybody of you ever solve this issue and could post a bit about it?

I never did get 1 of my 2 igor input amps working.  i tried swapping w/ 2 new bd139s TWICE,  w/ no luck.  so i was in the assumption it could possibly be one of the other transistors.  I plan to get back to it but haven't gotten to it yet.  However,  i am using a pair of the f76 and love them.  using an IC input amp and gar2520s on the outputs.  rev F style otherwise.

 

[kante1603]

Hi,

thanks for the reply.You haven't measured the bd139 by accident?
You have the gar2520 as output amp,does that mean you're running it on  +/-16vdc like a lunchbox or so?
I'm going 51x so that's sadly no option for me (except setting the jumpers and cutting goldfingers).
About ic input amp,would you prefer more this one or igor's cascode amp?
Don't want to go on your nerves,I'm just collecting possibilities and ideas,so mea culpa

Cheers,

Udo.

 

[kante1603]

For use with input IC amp, INSTALL R11' = 560k.

This resistor IS installed on "my" or "original" input amp PCB.

Hi all,

what does that mean for IJ input amp?
This question was asked before but never answered I think.
Can't find this 560k neither on his DOA pcb nor in the corresponding schematics or the bom.
So I "guess" r11' must be soldered in,right?

Can anybody confirm this please?

Thanks in advance,

Udo.

 

[Igor]

560k is resistor which pulling the input of first amplifier to ground or to its bias.
With IJ amp, no need for 560k, because it has own bias circuitry at its input already.

 

[Igor]

Anyway,did anybody of you ever solve this issue and could post a bit about it?

I never did get 1 of my 2 igor input amps working.  i tried swapping w/ 2 new bd139s TWICE,  w/ no luck.  so i was in the assumption it could possibly be one of the other transistors.  I plan to get back to it but haven't gotten to it yet.  However,  i am using a pair of the f76 and love them.  using an IC input amp and gar2520s on the outputs.  rev F style otherwise.

BD139 shouldn't be a problem. Check all other things, maybe, wrong value resistor or put 2484 instead of 4250, etc.

 

[kante1603]

560k is resistor which pulling the input of first amplifier to ground or to its bias.
With IJ amp, no need for 560k, because it has own bias circuitry at its input already.

Cool,

thank you very much Igor!

Udo.

...and thank you for explaining,it's way clearer now to me

 

[kante1603]

BD139 shouldn't be a problem. Check all other things, maybe, wrong value resistor or put 2484 instead of 4250, etc.

That would mean that quite a few guys here have similar problems,right?
O.K.,for easy swapping the other transistors (T1-T3) I think I will put in sockets,just to be save.

Thanks again,

Udo.

 

[kante1603]

Some progress in solving the mechanical stress on led alignment,bent motherboard and GR switch.

I did it this way (after some trials):

1)Align the leds exactly as described by Igor!!!
2)Cut off the six little plastic pins from the underside of the alps switch (for GR);it´s easy since it is just soft plastic.
3)Now put on the actuator cap and assemble the pcb to the L-bracket temporarily.The cap will "guide" the switch itself to a nearly perfect position!
4)Catch one(!) of the outer switch pins with a solder blob.By reheating it (not too long of course) you can make a final alignment although it is nearly unneeded then.
5)Solder the opposite outer pin then to make it "save".
6)Now disassemble the mainboard from the bracket and solder the remaining pins-done!

This will give you a perfect line-up without any stress on the board like our friend chunger had problems with.

Attached a pic to proof this,I took it half an hour ago.

All the best to you guys,

Udo

 

[kante1603]

Hi all,

Me again.
I'm using LL1524 as output transformer.
Can somebody please tell me the correct values for the zobel network meaning R101 and C100?
I have 1k (R84) as load as stated on the bom and schematics.

Thank you in advance,

Udo.

 

[chunger]

I used:

R101 469R
C100 4.7nf

It has worked well enough.

Hi all,

Me again.
I'm using LL1524 as output transformer.
Can somebody please tell me the correct values for the zobel network meaning R101 and C100?
I have 1k (R84) as load as stated on the bom and schematics.

Thank you in advance,

Udo.

 

[kante1603]

Thank you very much chunger,

have read that in this thread,but I am a bit confused because it says 469r here and 460r in another place.May I ask how you ended up in these values?
Tried a search for zobel network,seems quite complicated.

Best,

Udo.

 

[saxmonster]

Anyone make a stereo pair of these yet?  Did you have to match resistors or any parts when you built them or is the matching of a stereo pair done in the calibrating?

-Scott

 

[chunger]

I'd be the wrong person to ask.  I believe Igor suggested a range of values, and I selected the cap and resistor value inside that range that would attenuate the treble response least from a phone conversation with a friend squinting at the schematics.  I do not have much understanding of how the circuit works, but that was the value that I used for this transformer, and I can't complain about the resulting sonics.

Thank you very much chunger,

have read that in this thread,but I am a bit confused because it says 469r here and 460r in another place.May I ask how you ended up in these values?
Tried a search for zobel network,seems quite complicated.

Best,

Udo.

 

[kante1603]

@ chunger:Thank you very much for taking care!Meanwhile I got the information that Lundahls are not sensitive to this,so I'll leave them out first.In case if they will be needed I've put sockets to these positions.I have the 1k as load resistor.

@ scott:I'm close to finishing my pair.From what I understood Q1 & Q10 should be matched for stereo operation,Igor states this in the bom.I have his kits here,and these transistors came packed in aluminium foil.Don't know how this will work out at the moment,will see when I come to final setup and calibration.

Best,

Udo.