DIY PPM for 1176LN

Nutmeg II. · 17th September 2003, 12:14 AM

There are conections on the 1176 to plug in exernal metering, I'am intrested tu do a PPM that could be used there.
Anybody know were I can find a schematic?!?

gyraf · 17th September 2003, 11:22 AM

No. It's not easy anyway.

There are no connections on the 1176 for external metering.

There is a (voltage control) stereo interconnect jack that may be used for that purpose, but only if you build a separate GR-metering section - complete with matched FET and all - like the one already found internally in the 1176.

1176 rev#F Schematic:

http://www.gyraf.dk/gy_pd/1176/1176sch.gif

Best regards,

Jakob E.

Nutmeg II. · 17th September 2003, 03:13 PM

There are to conections on the Jones Barrier terminals that says Meter!?!

gyraf · 18th September 2003, 11:09 AM

Aah! But that's a re-issue model, with different connectors than the original 1176.

You should contact Universal Audio for details about this new meter output. It isn't present on any of the old 1176'es that I have seen, nor is it on any schematic I've come across.

Jakob E.

EDIT: I rechecked, and found an Universal Audio rev#D schematic WITH an option for external meter. In this case, the external meter output is either bridged (shorted) for use with internal meter only, or connected to an external VU-meter, that will then sit in series with the internal meter. My best guess is, that a standard Sifam AL-series VU-meter (the ones that are rated a 3k6 series resistor to show +4dBm as 0VU) will be right.

IF this is the way the reissue is made - I don't know about them - you should remember that the meter output is a current-through device - and that the only metering that can be connected here in a simple way is the mentioned moving-coil VU-meter...

Nutmeg II. · 18th September 2003, 05:20 PM

Thanks Jakob!

The signal driving the VU is recitfied, isn't it?

gyraf · 19th September 2003, 03:50 PM

Yep, a real VU-meter has an internal bridge rectifier.

But dosen't your manual say anything about this external meter connection?

Jakob E.

Nutmeg II. · 21st September 2003, 11:50 PM

Quote:

Originally posted by gyraf
...But dosen't your manual say anything about this external meter connection?...

Yep! It say to use a standard VU with it.
So what I'll need is a circuit that will convert VU input signal to a led meter.
Got one? I'll do a search on that.

gyraf · 22nd September 2003, 11:34 AM

That is not a simple task, I think.

The problem in this circuit is that you need to measure a current-through level, not referenced to a ground or anything. And this "floating" current-to-voltage converter needs to treat AC the same as DC.

A way to do it could be to use an analog-isolation opto-coupler, like a vactrol (LDR-based) or a H11F3 (FET-based). Linearity could present a problem here.

Jakob E.

Nutmeg II. · 22nd September 2003, 08:06 PM

Hmm?!? Sounds difficult to me. So I may pass o that project to. But still would be nice to have a dbx 160x style PPM meters on the 1176LN + a bypass!

gyraf · 22nd September 2003, 08:29 PM

A bypass? There is a bypass on it allready: it's on the click most counter-clockwise on the attack pot...

Jakob E.

Nutmeg II. · 23rd September 2003, 03:39 AM

That will bypass the gain reduction only and leave the amps in.
That doesn't help on ABing the compressed to the oriiginal signal!

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Help with my old 1176LN	ethan_c	So much gear, so little time!	0	6th September 2006 05:36 PM
2-1176LN ??	Finstad	High end	8	25th January 2004 09:44 PM

17th September 2003, 12:14 AM	#1
Nutmeg II. Lives for gear Join Date: Jan 2003 Location: GEARmany Posts: 905	DIY PPM for 1176LN There are conections on the 1176 to plug in exernal metering, I'am intrested tu do a PPM that could be used there. Anybody know were I can find a schematic?!? __________________ "Any recording engineer who uses a tube U47 is obviously not a professional" Stephan Temmer 1979

17th September 2003, 03:13 PM	#3
Nutmeg II. Lives for gear Join Date: Jan 2003 Location: GEARmany Posts: 905	There are to conections on the Jones Barrier terminals that says Meter!?! __________________ "Any recording engineer who uses a tube U47 is obviously not a professional" Stephan Temmer 1979

18th September 2003, 05:20 PM	#5
Nutmeg II. Lives for gear Join Date: Jan 2003 Location: GEARmany Posts: 905	Thanks Jakob! The signal driving the VU is recitfied, isn't it? __________________ "Any recording engineer who uses a tube U47 is obviously not a professional" Stephan Temmer 1979

22nd September 2003, 08:06 PM	#9
Nutmeg II. Lives for gear Join Date: Jan 2003 Location: GEARmany Posts: 905	Hmm?!? Sounds difficult to me. So I may pass o that project to. But still would be nice to have a dbx 160x style PPM meters on the 1176LN + a bypass! __________________ "Any recording engineer who uses a tube U47 is obviously not a professional" Stephan Temmer 1979

17th September 2003, 11:22 AM	#2
gyraf Gear addict Join Date: Jun 2002 Location: Denmark Posts: 493	No. It's not easy anyway. There are no connections on the 1176 for external metering. There is a (voltage control) stereo interconnect jack that may be used for that purpose, but only if you build a separate GR-metering section - complete with matched FET and all - like the one already found internally in the 1176. 1176 rev#F Schematic: http://www.gyraf.dk/gy_pd/1176/1176sch.gif Best regards, Jakob E.

18th September 2003, 11:09 AM	#4
gyraf Gear addict Join Date: Jun 2002 Location: Denmark Posts: 493	Aah! But that's a re-issue model, with different connectors than the original 1176. You should contact Universal Audio for details about this new meter output. It isn't present on any of the old 1176'es that I have seen, nor is it on any schematic I've come across. Jakob E. EDIT: I rechecked, and found an Universal Audio rev#D schematic WITH an option for external meter. In this case, the external meter output is either bridged (shorted) for use with internal meter only, or connected to an external VU-meter, that will then sit in series with the internal meter. My best guess is, that a standard Sifam AL-series VU-meter (the ones that are rated a 3k6 series resistor to show +4dBm as 0VU) will be right. IF this is the way the reissue is made - I don't know about them - you should remember that the meter output is a current-through device - and that the only metering that can be connected here in a simple way is the mentioned moving-coil VU-meter...

19th September 2003, 03:50 PM	#6
gyraf Gear addict Join Date: Jun 2002 Location: Denmark Posts: 493	Yep, a real VU-meter has an internal bridge rectifier. But dosen't your manual say anything about this external meter connection? Jakob E.

22nd September 2003, 11:34 AM	#8
gyraf Gear addict Join Date: Jun 2002 Location: Denmark Posts: 493	That is not a simple task, I think. The problem in this circuit is that you need to measure a current-through level, not referenced to a ground or anything. And this "floating" current-to-voltage converter needs to treat AC the same as DC. A way to do it could be to use an analog-isolation opto-coupler, like a vactrol (LDR-based) or a H11F3 (FET-based). Linearity could present a problem here. Jakob E.

22nd September 2003, 08:29 PM	#10
gyraf Gear addict Join Date: Jun 2002 Location: Denmark Posts: 493	A bypass? There is a bypass on it allready: it's on the click most counter-clockwise on the attack pot... Jakob E.

23rd September 2003, 03:39 AM	#11
Nutmeg II. Lives for gear Join Date: Jan 2003 Location: GEARmany Posts: 905	That will bypass the gain reduction only and leave the amps in. That doesn't help on ABing the compressed to the oriiginal signal! __________________ "Any recording engineer who uses a tube U47 is obviously not a professional" Stephan Temmer 1979

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes	Rate This Thread
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode	Rate This Thread: