All things G1176 - the new "repost" thread.
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MartyMart
Well-known member
Just putting together the 1176 REV G parts and have one question.
The 10v 1w zener ( CR-6 ) can it be subbed with a 9v1 1w
Or is the 10v needed "exact" ??
Thanks,
Marty.
The 10v 1w zener ( CR-6 ) can it be subbed with a 9v1 1w
Or is the 10v needed "exact" ??
Thanks,
Marty.
IMO it should be 10V as prescribed (and which is a common value) - but 9V1 might work.
Jakob E.
Jakob E.
MartyMart
Well-known member
[quote author="gyraf"]IMO it should be 10V as prescribed (and which is a common value) - but 9V1 might work.
Jakob E.[/quote]
Thanks Jakob , found some at RS for 19 pence each !!
MM.
Jakob E.[/quote]
Thanks Jakob , found some at RS for 19 pence each !!
MM.
Just finished wiring up my Mnats Rev J board with pushbuttons. My power supply voltages were correct so I moved on. Basically everything seems to be working fine except a very loud intermitent buzz. Nothing particular seems to cause the buzz just random switching of switches on the ratio or meter board. I tried rearanging some grounds and shorting inputs with no luck. The buzz goes away while waving your hand over the VR heatsink or completely by touching the top Q15. Anyone have any ideas what to look for? I've been troubleshooting all night and could use another perspective or some hints wth possible causes or places to look.
gswan
Well-known member
It's definitely your grounding if you can make it disappear by touching things like that.
Have you connected the chassis ground to the DC signal ground at the PSU, and only at the PSU (ie not multiple points)?
Have you connected the chassis ground to the DC signal ground at the PSU, and only at the PSU (ie not multiple points)?
Thanks Gswan,
Moving the toriod (that I hadn't yet screwed down for a reason) one inch solved the problem. Its as quiet as a mouse now. Too many hours spent trying to figure that one out but the pcb is now super clean due to some early morning scrubbing. Now onto calibrating.
Moving the toriod (that I hadn't yet screwed down for a reason) one inch solved the problem. Its as quiet as a mouse now. Too many hours spent trying to figure that one out but the pcb is now super clean due to some early morning scrubbing. Now onto calibrating.
keefaz
Well-known member
...
Oups misread your question, sorry
Oups misread your question, sorry
gswan
Well-known member
[quote author="louder"]Hi
I know i`ll be a ass with this question:
for starters,i finnished rev h.
the ratio sw,calls for 2 pole 6pos.
in the several panels i saw,there`s only 4 ratio options;so why 6 position sw?.
pedro[/quote]
It depends on exactly what you are building (ie whose plans and BOM). I added two more ratios to my unit so I have 4, 6, 8, 10, 12, 20 and used a 6-position rotary switch.
-Geoff
I know i`ll be a ass with this question:
for starters,i finnished rev h.
the ratio sw,calls for 2 pole 6pos.
in the several panels i saw,there`s only 4 ratio options;so why 6 position sw?.
pedro[/quote]
It depends on exactly what you are building (ie whose plans and BOM). I added two more ratios to my unit so I have 4, 6, 8, 10, 12, 20 and used a 6-position rotary switch.
-Geoff
Hi
i`m calibrating my 1176,but have questions:
in the meter(sifam al29),there is a litlle hole to calibrate the meter;do i have to mess with it?.
in bypass mode,the meter goes all to the left,wich i think it`s okay,but when in gr mode,it starts to go to the right,and stops only at the end.
is this okay?
i already passed some audio trough the unit,and it compress,and all the pot`s and sw,make changes,altough the unit is not calibrated.
i read everything about the calibration,and in bypass mode,the meter just stays dead to the left..
sorry for not being to clear.
best regards
pedro
i`m calibrating my 1176,but have questions:
in the meter(sifam al29),there is a litlle hole to calibrate the meter;do i have to mess with it?.
in bypass mode,the meter goes all to the left,wich i think it`s okay,but when in gr mode,it starts to go to the right,and stops only at the end.
is this okay?
i already passed some audio trough the unit,and it compress,and all the pot`s and sw,make changes,altough the unit is not calibrated.
i read everything about the calibration,and in bypass mode,the meter just stays dead to the left..
sorry for not being to clear.
best regards
pedro
gswan
Well-known member
Pedro,
It will depend on what you are metering at the time.
If you are metering gain reduction and 'bypass' (it's really not a bypass, just a gain-reduction disable function) the meter should show no movement, regardless of input signal.
You will need to calibrate the unit in order to get sensible readings though.
When you are metering signal level (+4 or +8) you should see the meter measuring the output signal directly.
-Geoff
It will depend on what you are metering at the time.
If you are metering gain reduction and 'bypass' (it's really not a bypass, just a gain-reduction disable function) the meter should show no movement, regardless of input signal.
You will need to calibrate the unit in order to get sensible readings though.
When you are metering signal level (+4 or +8) you should see the meter measuring the output signal directly.
-Geoff
gswan
Well-known member
[quote author="louder"]Hi
i`m calibrating my 1176,but have questions:
in the meter(sifam al29),there is a litlle hole to calibrate the meter;do i have to mess with it?.
[/quote]
The meter has a zero offset adjustment, which is a mechanical adjustment of the spring so that the meter reads zero in the absence of power.
With the power off, adjust this until the needle sits on the left-hand minimum marking.
-Geoff
i`m calibrating my 1176,but have questions:
in the meter(sifam al29),there is a litlle hole to calibrate the meter;do i have to mess with it?.
[/quote]
The meter has a zero offset adjustment, which is a mechanical adjustment of the spring so that the meter reads zero in the absence of power.
With the power off, adjust this until the needle sits on the left-hand minimum marking.
-Geoff
Hi Geoff
thank you so much for your care.
but let me be more precise:
my 1176 has a 3 pos sw:bypass/gr/vu.
in all the reading i`ve done,they all say to put the unit in bypass mode for at least some of the calibration steps.
so:if in bypass mode the meter is not suposed to move,why the manual says to do so?.
let me ask:in bypass mode,all the controls of the unit aren`t suposed to act:right?.
best regards
pedro
thank you so much for your care.
but let me be more precise:
my 1176 has a 3 pos sw:bypass/gr/vu.
in all the reading i`ve done,they all say to put the unit in bypass mode for at least some of the calibration steps.
so:if in bypass mode the meter is not suposed to move,why the manual says to do so?.
let me ask:in bypass mode,all the controls of the unit aren`t suposed to act:right?.
best regards
pedro
gswan
Well-known member
Hi Pedro,
Take a look at the circuit. Does the 'bypass' position connect the input connector directly to the output connector and isolate the compressor? If it does then it's a bypass, otherwise it is something else.
The 'bypass' mode of the 1176 disables the gain reduction, however the signal still travels through the unit and will be affected by the input and output controls.
The other two positions on the switch refer to the metering modes. The meter can either be switched to meter gain reduction, or to measure the output signal (VU). This is usually calibrated to +4dBu. My unit is a little different since I made a few mods to include the +8dBu setting as well, and had the 'gr disable' function on the attack pot (which has a switch).
The confusion comes about because the original 1176 has the 'bypass' (or GR disable) switch on the attack pot, not on the metering switch. So the calibration is asking for the metering to be in either GR or +4dBu position and for the GR amp to be switched in or out ('bypass').
You will need to bear this in mind when you do your calibration and find a way to disable the GR amp whilst still having the meter set to the appropriate position.
cheers,
Geoff
Take a look at the circuit. Does the 'bypass' position connect the input connector directly to the output connector and isolate the compressor? If it does then it's a bypass, otherwise it is something else.
The 'bypass' mode of the 1176 disables the gain reduction, however the signal still travels through the unit and will be affected by the input and output controls.
The other two positions on the switch refer to the metering modes. The meter can either be switched to meter gain reduction, or to measure the output signal (VU). This is usually calibrated to +4dBu. My unit is a little different since I made a few mods to include the +8dBu setting as well, and had the 'gr disable' function on the attack pot (which has a switch).
The confusion comes about because the original 1176 has the 'bypass' (or GR disable) switch on the attack pot, not on the metering switch. So the calibration is asking for the metering to be in either GR or +4dBu position and for the GR amp to be switched in or out ('bypass').
You will need to bear this in mind when you do your calibration and find a way to disable the GR amp whilst still having the meter set to the appropriate position.
cheers,
Geoff
lofi
Well-known member
just a heads up to let you guys know i will be dropping by soon, just read all of these 97 pages and start ordering parts tomorrow....
i think the phrase is 'run away'
:grin: :sam: :sam: :guinness:
i think the phrase is 'run away'
:grin: :sam: :sam: :guinness:
Brown Note
Well-known member
Hi all,
I finally got around to finishing my mnats G1176. I chose to use the opamp input with an Edcor XS1100 for output. It passes signal and compresses, but it is not happy.
Here's a sweep in bypass mode. Right channel is through the 1176 with the input and output controls maxed. My sound card has a 100ohm output and a 32k ohm input.
The poor frequency response and low output persist in GR mode.
Any suggestions on where to start troubleshooting? Thanks!
Ben
I finally got around to finishing my mnats G1176. I chose to use the opamp input with an Edcor XS1100 for output. It passes signal and compresses, but it is not happy.
Here's a sweep in bypass mode. Right channel is through the 1176 with the input and output controls maxed. My sound card has a 100ohm output and a 32k ohm input.
The poor frequency response and low output persist in GR mode.
Any suggestions on where to start troubleshooting? Thanks!
Ben
gswan
Well-known member
Start by checking where the response starts to suffer.
Inject your sweep and check it at the output of the input amp (ie top of input pot). Then check it at the output pot and then at the output of the transformer driver.
At a guess I'd say you have a component error in the output driver amp.
Inject your sweep and check it at the output of the input amp (ie top of input pot). Then check it at the output pot and then at the output of the transformer driver.
At a guess I'd say you have a component error in the output driver amp.
Brown Note
Well-known member
Thanks gswan!
I wish I would have thought of that. It's the transformer. The signal is flat all the way up to the Edcor. I'll check to make sure I wired it correctly before I pull it.
Ben
I wish I would have thought of that. It's the transformer. The signal is flat all the way up to the Edcor. I'll check to make sure I wired it correctly before I pull it.
Ben
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