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

[kante1603]

IM nearly complete w/ 2 units.  i went to calibrate and both units seem to pass signal directly thru the units with no power.  I just plugged into my test card,  sent a sine wave and the signal passed right thru.  Almost like the input/output is shorted.  is this supposed to happen?  anyone have any idea whats going on?  the same on both units,  eveything looks ok though.

using balanced line receiver, b11148,  +-16v (500 spec)

Hi

Don't know this piece yet,but looking on the pics it has got relais as well as a bypass switch on the front.Now guess.....

Udo.

 

[qmp audio]

IM nearly complete w/ 2 units.  i went to calibrate and both units seem to pass signal directly thru the units with no power.  I just plugged into my test card,  sent a sine wave and the signal passed right thru.  Almost like the input/output is shorted.  is this supposed to happen?  anyone have any idea whats going on?  the same on both units,  eveything looks ok though.

using balanced line receiver, b11148,  +-16v (500 spec)

Hi

Don't know this piece yet,but looking on the pics it has got relais as well as a bypass switch on the front.Now guess.....

Udo.

yes i see the relays are opening the circuit like a hard bypass.  These relays aren't receiving the signal to close.  I'm having this issue with and without the GR board connected.  both units are functioning the same,  so whatever the issue is it persists across both modules.  I'm looking closely at the solders and components and everything looks right (comparing w/ chunger's photos).  I'm getting the proper voltage readings  (step one of igor's test procedures).  Anyone familiar with this have any idea where to look,  or where to start w/ this?

 

[kante1603]

yes i see the relays are opening the circuit like a hard bypass.  These relays aren't receiving the signal to close.  I'm having this issue with and without the GR board connected.  both units are functioning the same,  so whatever the issue is it persists across both modules.  I'm looking closely at the solders and components and everything looks right (comparing w/ chunger's photos).  I'm getting the proper voltage readings  (step one of igor's test procedures).  Anyone familiar with this have any idea where to look,  or where to start w/ this?

I´m not sure if I really get you right,but I did a quick look at the schematics some minutes ago.The relais bypass circuit is shown at the upper right corner.
See it as toggle switches with a single "input" to two "outputs",this is also called "failsafe mode".The unit powered off causes the relais to connect the inputs to the outputs.This is the default condition of the relais.Therefore it is correct that the board passes audio when not powered up!Looking good so far,don´t worry.

Hope to have helped,

Udo

 

[qmp audio]

yes i see the relays are opening the circuit like a hard bypass.  These relays aren't receiving the signal to close.  I'm having this issue with and without the GR board connected.  both units are functioning the same,  so whatever the issue is it persists across both modules.  I'm looking closely at the solders and components and everything looks right (comparing w/ chunger's photos).  I'm getting the proper voltage readings  (step one of igor's test procedures).  Anyone familiar with this have any idea where to look,  or where to start w/ this?

I´m not sure if I really get you right,but I did a quick look at the schematics some minutes ago.The relais bypass circuit is shown at the upper right corner.
See it as toggle switches with a single "input" to two "outputs",this is also called "failsafe mode".The unit powered off causes the relais to connect the inputs to the outputs.This is the default condition of the relais.Therefore it is correct that the board passes audio when not powered up!Looking good so far,don´t worry.

Hope to have helped,

Udo

Yes thanks Udo for looking into this.  The issue i'm having is the signal is still bypassed when i power up.  Im testing the voltage and the amps are getting power and the leds are lighting up,  but the bypass still active when powered.  Been studying the schematics and pcbs and can't seem to find why this is happening when its powered up.

 

[kante1603]

Can you hear the relais cicking when you toggle the bypass switch?
Maybe just the switch miswired?
Measure if the control voltage is there at the relais corresponding to the switch position?

As said I don't know this piece yet and therefore haven't built one.

Maybe somebody who has already built them could chime in?

Udo.

 

[zayance]

Even when you add the jumper on the 10 Pin connector without the control board?


EDIT: wait, you forgot to put R95, a 1/2W resistor, check the BOM and Schematic for an explanation on this, because the value depends on Coil resistance.
I see you use kit from Igor, so the coil resistance of his relays must be 1K (check it tough) That means that R95 should be about 330 ohms 1/2Watt.

 

[qmp audio]

EDIT: wait, you forgot to put R95, a 1/2W resistor, check the BOM and Schematic for an explanation on this, because the value depends on Coil resistance.
I see you use kit from Igor, so the coil resistance of his relays must be 1K (check it tough) That means that R95 should be about 330 ohms 1/2Watt.

Good eye!  Thanks!  Calibrated and functional!  Thanks Everyone on here for your notes and info,  and Igor this things great.

My second unit is getting the same V reading Chunger had on the input amp (~13v).  So just ordered some new bd139s to test.

One other question,  my GR meter seems pretty calibrated,  except it goes crazy w/ the slam switch engaged.  is this expected?  pretty much goes the full range of the LED,  where as all other GR settings go from 0 down appropriately.

 

[zayance]

One other question,  my GR meter seems pretty calibrated,  except it goes crazy w/ the slam switch engaged.  is this expected?  pretty much goes the full range of the LED,  where as all other GR settings go from 0 down appropriately.

expected

 

[qmp audio]

Hello again everyone.  I'm having trouble tracking down the issue w/ one of the ig se-cascode input amps.  the measurement on the amp is ~15V.  (I'm testing on a 16v lunchbox ps).  I saw changer had a similar problem,  so i replaced the bd139s as it had worked for him.  Same 15V measurement.  I double checked resitances,  and examined for any shorts etc.  everything seems to match my working on.  Could this be an issue w/ t1, t2, or t3?  the values are right,  could one of these components be bad?

Also,  does any know what kind of other input amps can be used? (16v)
Thanks for any insight.  I have one module finished!  the second is keeping me stuck on this non-functioning input amp.
qmp

 

[wowi]

Similar problem as gunpoint recording. Measurement at the ig input amp is 22,85 V with 51x. I checked everything and like gunpoint recording i replaced the BD139s. I build two 51X-F76 and got the same Measurement on both !

Any ideas ?
Wolfgang

 

[qmp audio]

Similar problem as gunpoint recording. Measurement at the ig input amp is 22,85 V with 51x. I checked everything and like gunpoint recording i replaced the BD139s. I build two 51X-F76 and got the same Measurement on both !

Any ideas ?
Wolfgang

Hello Wolfgang.  I never did figure out the problem w/ my 2nd ig input amp.  One specced just fine and worked,  the other did not.  i replaced the transistors and checked every component.... same ~16v measurement.  Keep me posted if you figure anything out.  In the meantime i ordered 2 ( http://www.digikey.com/product-detail/en/AD711KNZ ) IC opamps and extra pins for use with the IC input option.  You could get the opa604 for that.  I want to revisit the ig input and try to figure that out,  but for now 16v IC input and sl2520 output's working great for me.

I have read posts about people receiving faulty/counterfeit bd139s,  and that a large number of fakes may have entered the market.  Though i find it hard to believe that each of the 6 bd139s i tried are faulty ( i ordered in the US from digikey ).  However... i can't think of anything else that could be wrong w/ the amp  :-\

 

[chunger]

hey guys,

Sorry you're having problems with the Cascode opamp.  I figured there were only 5 transistors on there, so I started replacing them one at a time until it worked.  I'm not electronically literate, but going over the schematic with a friend indicated the BD's were likely suspects.  I hope you're able to get it sorted out.

Long-term report. . . we have been using one of the F76 units in the studio for a few months now configured as built in this thread.  input/output pots, Cascode input amp, IC receiver, original output amp, Lundahl output transformer, and it's been working really well on vocals and guitars at the studio.  It is a bit thin and overdrives a bit too early and gritty for heavy things like bass.

I brought a 2nd unit into the studio recently configured with an APP2520E which loves to run at +-24V as output amplifier trying to decide which configuration we like better for a matched pair.  This setup ended up being smoother with a lot more bottom and a silkier top end.  Great for bass, snare, kick, but on vocals, we liked the way the original output amp breaks up and gives a hint of bite to female vocals.  Ended up leaving them in different configurations.  Maybe i will have to build another one if i want to run a stereo pair.

But, I know Igor prefers his Albatross amp in this device.  Alternately, for a more pristine sound with lots of headroom, the APP2520E available in the white market might be something to consider.  Note: Do to the height of the potted opamp, I had to cut a little bit of the F76 upper PCB with a file to fit, but no problems.  That part does not have any components even close.

We use the 2:1 ratio all the time making F76 do things the original would not be able to do.  VERY nice feature.

 

[mulletchuck]

Any folks who have a pair of these who live in NYC??  I'd like to compare mine and see if you can help me see if i have them properly set up.    Send me a PM if you do.

 

[odfull]

Hi,

I'm building a 51x76 with a B11148 output transformer. I'm not an electronics engineer and I'm afraid to make a mistake. Does anyone can tell me if it's the right way wiring it like this:
- Brown and Orange on out_tr+1
- Red and Yellow on out_tr-2
- Green and Violet on out_tr+3
- Blue and Grey on out_tr-4

Another question from a newbies:
on mother board, in the detector section, 6.8Uf electrolitics caps are used for C19 and C20. On a previous BOM I read 6.8....10uf tan tall caps. I have 10uf tantall caps. Can I put them, or is it preferable that I follow the last version of docs and put 6.8uf ?
For my knowledge, what's the difference? Is the detector more sensitive with 6.8uf or anything else?

Thanks
Thierry

 

[briomusic]

That's the way I have my B11148-500 wired (both sides parallel). Unfortunately there is no technical info on the hairball site, I found a quote from Ed Anderson on this board:

the b11148 is a 1+1:3.5+3.5 ratio, with something like a 150 ohm primary impedance.  it is not gapped, so there must be a cap or some other means to block DC from flowing in the primary.

With this wiring I have a gain of +41.5dB with both pots on maximum. I am not sure if this is ok or too much.
I also don't know if a Load Resistor and/or Zobel network is required.

Hi,

I'm building a 51x76 with a B11148 output transformer. I'm not an electronics engineer and I'm afraid to make a mistake. Does anyone can tell me if it's the right way wiring it like this:
- Brown and Orange on out_tr+1
- Red and Yellow on out_tr-2
- Green and Violet on out_tr+3
- Blue and Grey on out_tr-4

Another question from a newbies:
on mother board, in the detector section, 6.8Uf electrolitics caps are used for C19 and C20. On a previous BOM I read 6.8....10uf tan tall caps. I have 10uf tantall caps. Can I put them, or is it preferable that I follow the last version of docs and put 6.8uf ?
For my knowledge, what's the difference? Is the detector more sensitive with 6.8uf or anything else?

Thanks
Thierry

 

[kante1603]

Hi Igor,

have sent a mail to your yahoo adress concerning my order.

Cheers,

Udo.

 

[Igor]

Yes, shipped. It sometimes goes with delay to answer forum-related things, but I try to do my best
May take some time due to local holidays, crazy time - half week, everything is dead, then, day-two of work, than, back.
Mostly caused by happy penguins (don't mess with Linux), we celebrating 5773 New Year.

 

[kante1603]

Hello Igor,

package received today,but.......

Have sent an email to your yahoo adress.

Best regards,

Udo.

 

[Igor]

Answered by mail. In case of whatever: should be 2 packages, and black anodised Aluminum fronts will arrive separetely.

 

[kante1603]

Answered by mail. In case of whatever: should be 2 packages, and black anodised Aluminum fronts will arrive separetely.

Thanks Igor,

did you put the Alps switches in as well?

Cheers,

Udo.