[BUILD] 1176 Rev F/G - new board, new transformer!

[hymentoptera]

dmnieto, what were your attack, release and ratio settings for these examples?

 

[dmnieto]

1:8, attack around 5, release around 6

 

[hymentoptera]

1:8, attack around 5, release around 6

I'm just wondering how much of a factor tiny variations in pot settings and parts tolerances played in the samples.

 

[dmnieto]

I didn't touch it..., in any case the syntetic measures with pulses showed the same kind of response...It just that the capacitor change the tone more than expected

 

[dmnieto]

i have one question... the original UREI rev f schematic (http://www.gyraf.dk/gy_pd/1176/1176sch.gif) there was an output matching resistor of 1K in the output... Any reason mnats' design does not include it?

 

[mnats]

i have one question... the original UREI rev f schematic (http://www.gyraf.dk/gy_pd/1176/1176sch.gif) there was an output matching resistor of 1K in the output... Any reason mnats' design does not include it?

The answer is that the schematic you linked to isn't a Rev F.

 

[dmnieto]

The answer is that the schematic you linked to isn't a Rev F.

Sorry, I linked the wrong schematic.

I was actually curious about the difference between the outputs of rev f and ref g, in the jbl pro manual.

For rev f there isn't any output resistor, wiring both of the primaries in parallel and the secondaries in parallel.
For ref g, the secondaries are still in parallel, but they have a 1K (R84) resistor when wired 1:10 (on 1:1 the output is connected to the second primary).

So in 1:10 config, rev f and rev g differ in that there is a 1K resistor across the output on the later. I understand that mnat's purpose was to stay as close as possible to the rev f schematic, but my question still stands in a different form: What is the purpose of R84?

It is to be able to connect it to modern hi-input lines? to have the next load see a constant impedance at the output.

My question is because I am in the process of building a pultec eqp-1a based on gyraf's design, which is spec'ed to be driver with a low impedance to prevent a bass roll-off. I want to be sure that I can connect the output of the 1176 both to a modern line-in or to the pultec, and i am not sure which of the options would be better:

rev f output: 600 Ohm.
ref g 1:10 output: with R84 1K
ref g 1:1 output: 60 Ohm.

 

[mnats]

Sorry, I linked the wrong schematic.

I was actually curious about the difference between the outputs of rev f and ref g, in the jbl pro manual.

For rev f there isn't any output resistor, wiring both of the primaries in parallel and the secondaries in parallel.
For ref g, the secondaries are still in parallel, but they have a 1K (R84) resistor when wired 1:10 (on 1:1 the output is connected to the second primary).

So in 1:10 config, rev f and rev g differ in that there is a 1K resistor across the output on the later. I understand that mnat's purpose was to stay as close as possible to the rev f schematic, but my question still stands in a different form: What is the purpose of R84?

It is to be able to connect it to modern hi-input lines? to have the next load see a constant impedance at the output.

My question is because I am in the process of building a pultec eqp-1a based on gyraf's design, which is spec'ed to be driver with a low impedance to prevent a bass roll-off. I want to be sure that I can connect the output of the 1176 both to a modern line-in or to the pultec, and i am not sure which of the options would be better:

rev f output: 600 Ohm.
ref g 1:10 output: with R84 1K
ref g 1:1 output: 60 Ohm.

Putting a load resistor across the output does not change the intrinsic output impedance of the line amp just as putting more people in the car doesn't reduce the horsepower of your vehicle.

What might have escaped your attention is that the F and G use different output transformers. Ed's repro is based on the Bourns model used in the former revision.

 

[SaMpLeGoD]

Hello all, got my 1176 Rev F back again and I'm still trying to solve some issues...
I don't know why, my comp only starts compressing at 3 o'clock...  I have a Rev A, Rev D fully functional and doing what I expect, so I'm wondering why this one doesn't react the same way.

I did the calibration as usual... the FET conduction went ok, and here starts the problems... as long as I'm using IC based input (no input trafo like my rev A and D), I don't know why I can't get the drop when I put pad 22 to ground (switching the attack knob off)... just nothing happens... I thought maybe the IC gain stage isn't amplificating too much so I swap R1A by a larger value, trying to increase the gain, reaching the threshold faster... I though, but no... still compressing only when 3 o'clock is reached...

Another strange thing... with the comp bypassed, and setting the knobs to read 0VU with a sine wave 1Khz, 0.775V  (0dB) on the input, it's supposed I read 1.23v at the output, like I can in my other 2 comps!!!! but it doesn't happen... all I can get is around 327mV at the out althrought my meter shows me 0VU (1.23v)...

The wiring and values is cheked and ok, nothing messed with the out trafo wiring... the meter is wired directly to the XLR out right? pin 2 and 3... through a 3.9K resistor... why is that happening????? any thoughts?

Bad VU? Problem with the IC gain stage? any help is welcome...

I'm leaving a pic of what I explain here...
Thanks

Ed

 

[SonicSonar]

Hello

For Q2,Q3,Q4,Q5,Q12,Q13,Q14,Q15  can I use 2N3708 instead of the hard to get in the US BC107B?

Thanks

 

[SaMpLeGoD]

Use 2N5088... Cheap and Easy to find with a high HFE. Be sure to use the extra pad available on the board!
Happy new year to all!
Cheers

 

[SonicSonar]

Use 2N5088... Cheap and Easy to find with a high HFE. Be sure to use the extra pad available on the board!
Happy new year to all!
Cheers

Thank you.

 

[mnats]

Hello

For Q2,Q3,Q4,Q5,Q12,Q13,Q14,Q15  can I use 2N3708 instead of the hard to get in the US BC107B?

Thanks

Are you sure you'rebuilding a F/G?

BC107 has never been suggested for this build.

 

[SonicSonar]

Correct.

It is the J board.

Sorry, wrong thread.  Needs to be in the Graf version

 

[metacarple]

Hey just finished my rev F kit, calibrated, and tested. Seems to work great, just wondering about one thing. when there is no signal coming through the chain, and the output knob is turned anywhere past 2 o'clock, there is some line noise... Is this just a gain issue, or is it an electrical issue? Has anyone experienced a similar issue?

Thanks!

 

[mnats]

Hey just finished my rev F kit, calibrated, and tested. Seems to work great, just wondering about one thing. when there is no signal coming through the chain, and the output knob is turned anywhere past 2 o'clock, there is some line noise... Is this just a gain issue, or is it an electrical issue? Has anyone experienced a similar issue?

Thanks!

Please read the troubleshooting FAQ linked from the first post of this thread. There are also some hints on my wiring pages regarding this issue.

 

[alchemystudio]

Hello Mnats!
My first build 1176 rev G was a failure ... :-[

I checked each elements multimeter.
Superb sound! and no noise but:
- Unable meter VU meter to zero.
- Compress, but choosing 4, 8, etc. does not change
- Lack 10db output.
I do not know where I was wrong!

I buy a new pcb (revG) to start again ...
I have a few questions ...
BOM front page post is still OK? I do not see where to put these elements Mouser:

ERO-S2PHF4R30 (2 resistors) (4.3 Ohms)
10Mohms (1 resistor)
6.8uF 63V (1 capacitors)
EEU-FC1H470H (3 capacitors) 47uF / 50V
and .. 1 WIMA capacitors 400V 2200pF Film

I'm sorry to ask, but I do not speak English, I do my best to read all the questions and answers but it's hard to understand everything.

Maybe I have an answer? 
Thank you very much for your help!!!!!

 

[hymentoptera]

...
I have a few questions ...
BOM front page post is still OK? I do not see where to put these elements Mouser:

ERO-S2PHF4R30 (2 resistors) (4.3 Ohms)
10Mohms (1 resistor)
6.8uF 63V (1 capacitors)
EEU-FC1H470H (3 capacitors) 47uF / 50V
and .. 1 WIMA capacitors 400V 2200pF Film
...

The little 4R3 resistors go at R40 and R41 in the Signal Line Amp.
I'm not sure there is a 10Meg resistor in this kit. Do you mean 1M, or perhaps 10k? There are several.
The 6.8uF, is this aluminum or tantalum? Probably the tantalums in the GR Amp
47uF, C11, and C18, and if using the IC input optino (no tranformer) also C34, they are found near various transistors.
The WIMA is C13< Signal Line Amp

 

[alchemystudio]

Thank you very much hymentoptera, your help is much appreciated!!
You were right! I must be blind (or stupid)

6.8uF is a mystery ...
C30, C31 6.8uF capacitors BOM application electrolytic ... OK i have 100-Volt Aluminium electrolytic capacitors 6.8uF.
C19, C20 6.8uF capacitors BOM application tantalum ... OK i have 35Volts 6.8uF Kemet Tantalum capacitors.

I still have a 6.8uF 63V (it's Aluminum Electrolytic Capacitor)!?! The Bom there are only 4 x 6.8uF Why I have 5? HA HA
http://ch.mouser.com/ProductDetail/Panasonic/EEU-FC1J6R8/?qs=sGAEpiMZZMtZ1n0r9vR22Sj5C48xJI9QiDtPMHxq2Hc%3d

Neither do I. I do not understand why I have a resistor of 10Meg ... I received by mouser!
http://ch.mouser.com/ProductDetail/Xicon/291-10M-RC/?qs=sGAEpiMZZMu61qfTUdNhG2ZvKd0YdoZGLMrPwD4RDKI%3d

Someone an idea?
Thank you again!

(sorry for my bad english)

 

[dmnieto]

Thank you very much hymentoptera, your help is much appreciated!!
You were right! I must be blind (or stupid)

6.8uF is a mystery ...
C30, C31 6.8uF capacitors BOM application electrolytic ... OK i have 100-Volt Aluminium electrolytic capacitors 6.8uF.
C19, C20 6.8uF capacitors BOM application tantalum ... OK i have 35Volts 6.8uF Kemet Tantalum capacitors.

I still have a 6.8uF 63V (it's Aluminum Electrolytic Capacitor)!?! The Bom there are only 4 x 6.8uF Why I have 5? HA HA
http://ch.mouser.com/ProductDetail/Panasonic/EEU-FC1J6R8/?qs=sGAEpiMZZMtZ1n0r9vR22Sj5C48xJI9QiDtPMHxq2Hc%3d

Neither do I. I do not understand why I have a resistor of 10Meg ... I received by mouser!
http://ch.mouser.com/ProductDetail/Xicon/291-10M-RC/?qs=sGAEpiMZZMu61qfTUdNhG2ZvKd0YdoZGLMrPwD4RDKI%3d

Someone an idea?
Thank you again!

do you speak german, italian or french?

(sorry for my bad english)