All things G1176 - the new "repost" thread.

[dukasound]

[quote author="khstudio"][quote author="dukasound"]Excuse me if I missed
Phase on output transformer (Lundahl) of Mnats and Jacobs project are diferent.[/quote]
I THINK Mnats just flipped the PAD's & not the Phase but I'm not sure :?:
Kevin[/quote]
Please compare Lundahl polarity with + and - signs on pcb.

 

[enthalpystudios]

original is 1:3.5

10db of transformer gain

mnats has 1:2, 6db of o/p tx gain.

gustavs board is 1:1, 0 o/p tx gain, ignoring losses on all those numbers


currently i have stancor wf30 1:1 on the input, and oep on the output at 1:2, mnats board.

i have way more gain than i could hope to use.

in fact, this thing is cool for dynamics. and i went to a buddy's and tracked some p-bass direct in, no di, and for one song it sounded awesome. on another it was good, but not what the song called for.

regardless, theres tons and tons of gain.

i'm actually thinking about building the electronically balanced version, just because its 'normal' and is according to the rev F schematic, and then pulling the oep and putting on a hand wound clone of the old one.

i'll report back when i get a chance to do this....

 

[khstudio]

Great info :thumb:

BUT... I was reffering to the Input Tranny :green: My fault.

The Mnats board has the option for 1:1 or 2:1 for the Lundhal...

Which is the setup most of you are going with & why?
It says 1:1 is normal but I think the original is 2:1, no? Confused

Also, any difference between using the 10k or 12k for the secondary loading Question

Thanks,
Kevin

 

[enthalpystudios]

got you ;]

sorry.... it seemed duka was mentioning the o/p, so i thought it was continuing...

anyway, g1176 is like a rev F with a rev G (5532) frontend.

the rev F has an O-12 with 500:200 (1.58:1) ratio..... witha constant impedance presented to the input transformer.

g1176 with an i/p transformer is on the pcb as 1:1, but in my very humblest opinion, i would go for 2:1 stepdown.... its a matter of 2 solder connections, so try it and see what you think of each..... see how much headroom you get on the input knob, and where your compression is kicking in (threshold) when you set up the box.

its really something that should be done with 'feel'

having tried a stancor wf30 onmy input as both 1:1 and 2:1, i'm honestly not a huge fan of either.... personal opinion, and an opinion that has no experience with a real 1176. just not working the way i want it to.

thats why i'm going to build the 5532 section, and test out this o/p tx clone.... hopefully my hand-wind will work out ok, and hopefully i can try it side by side later tonight and report back.

have to go to mcmaster for a 24mm step drill and some garolite ;]

but honestly it comes down to seeing what you like... its kinda personal. theres no right way in this situation, because the g1176 with i/p tx isn't like any of the orig. 1176ln's, so 'right way' is moot. go for what sounds good and works well for you.

if you're after 'original,' and its important that its like a 'real' one, go elec. balanced, or find yerself a t-attenuator and a utc O-12, or even an a-20 would work out... the stancor wf-30 i have is a clone of an a-20, same specs... and the O-12 in the original is just the mini/ouncer version of the a-20 (essentially).....

there are some other threads around (cant remember which) that also have some opinions, thoughts, and facts regarding the input transformer and the g1176 (and 1176ln)

 

[khstudio]

Thanks for your advise & input :thumb:

I'm finishing up 2 units TONITE :green: & NEED some last minut advise:

The pins that connect the main board to the Ratio switch board -
Do any of them NEED to be shielded :?:

pins ( 22 21 19 7 20 18 )


Is it OK to use SOLID CORE wire for those :?:
- I know it can break easier but are there any SONIC benifits to either :?:

Thanks,
kevin

 

[Greg]

I ONLY shielded I/O wires, NOT the wires to the RATIO switch.

Don't expect any SONIC difference between stranded or solid.

 

[khstudio]

[quote author="Greg"]I ONLY shielded I/O wires, NOT the wires to the RATIO switch.

Don't expect any SONIC difference between stranded or solid.[/quote]

Cool :thumb:

I assume your unit is working fine (Quiet) or you'd have said something by now.

Thanks man,
Kevin

 

[enthalpystudios]

also, the schematic shows what was shielded on the urei's

theres an "imaginary" sleeve indicating shield.

some of the frontpanel wiring was shielded, some was not, although most likely none of it is super critical.

your choice.... BUT check out mnats page for his wiring instructions.... really really helpful.....

 

[Greg]

I used the original Gyraf board, so I had to cut a trace or two and beef up the ground plane to get it quiet (and it's very quiet). But no worries on the mnats version. Only other thing I did was used shielded cables on the I/O.

 

[imo]

I hope everyone is well, recording, building, etc.
I just got back from another short tour and had a couple of continued questions/ queries about the 1176 threshold. Brad, apologies in advance, but it seems that i still haven't solved my threshold issues.
Jakob had suggested a mod putting a 100k trimpot in series with the sidechain input: one side to the top leg of the output pot, the wiper to the 56k(r26) at input and the other side of the trimpot to ground. When i originally connected the trimpot i accidentally connected the wiper to the other side of R26( between it and the 68k(R25)). When i connected it to the correct side and put the unit on a scope i wasn't able to see any alteration of threshold at all through the whole run of the trimpot. Ironically connecting the wiper between R26 and R25 gave me exactly what i was looking for(being able to take the threshold to a more usable level). This has left me a bit baffled as to what is going on. Am i missing something here??
I have also read a bit about some of the 1176 variations using a 2:1 stepdown transformer, which would seem to offer a more usable threshold.
Using the trimpot the way i am, the ratios seem pretty close, the only problem being the 4:1 is closer to 5:1. The other ratios are almost spot on..
Brad, did you ever put the unit on the scope while turning the trimpot? I am wondering if you possibly hooked it up the same way i did by accident, or if i am simply completely turned around.
Ian

 

[mnats]

[quote author="dukasound"]Excuse me if I missed
Phase on output transformer (Lundahl) of Mnats and Jacobs project are diferent.[/quote]
I'm not sure if I understand correctly, but then I don't have Jakob's board in front of me either. But what I do have are my own boards and the Lundahl and OEP output transformers that fit in them.

Here are two images of a 1kHz sine wave at the input and output of a working 1176 using my boards. First with the OEP:

The smaller trace is the input and the larger is the output of the OEP with the probes on the + side.

Next the Lundahl:

It looks correct to me and seems to agree with the designations on my boards. Are you saying that Jakob's boards work differently? Can you show us?

 

[Greg]

Those look in phase to me :thumb:

Except one of those sine waves in the second shot seems to be "bulging" a little.

 

[dukasound]

OK
Bad english :sad:
I ask this:
If we used Lundahl on out and wired 1:2 or 2:1. Both primary and secondary are wired in series.
On both Jakobs and Mnats boards C15 ? 470uF is connected to minus of Lundahl transformer (pin 1 for 2:1 and pin 10 for 1:2) and plus of windings (pin 4 and can 3 for 2:1 and pin 7 for 1:2) goes to ground.
On Jakobs pcb Bal. Out plus goes to pin 9 who is positive.
On Mnats board (1:2 ratio) Bal out plus goes to pin 5 who is negative.
It is it.

 

[mnats]

I get it now - you're saying the polarity of the output is reversed on Jakob's layout. Can anyone who has built one confirm with a simple test?

Anyway, it's an easy fix - just switch the wires.

 

[Greg]

I'll grab my G1176 in the coming days and see if the polarity is being inverted.

 

[dukasound]

[quote author="mnats"]I get it now - you're saying the polarity of the output is reversed on Jakob's layout. Can anyone who has built one confirm with a simple test?

Anyway, it's an easy fix - just switch the wires.[/quote]
OK.
We discuss here to learn anything :grin:

 

[W DeMarco]

Hiya folks,

Lookin forward to gettin my G fired upp but I am experienceing a couple of problems. First thing is that my VU is pegged full right in GR. Its a sifam 29, brand new, with the 24 volt light box!!. It seems to fuction well in VU mode and really extra well in Bypass. Here are a couple of things i've attempted that are suggested in the forum.

replaced VU fet.
pulled a bunch of resistors and replaced.
replaced tl071

I know the trim is working cause if I put enough input it compresses enough to where I can trim it up and down. although the trim doesnt affect the VU when no compression is happening. Im not sure I need a resistor attached to the VU. I have a 3k6 on that bastard right now but noticed that the 1k test tone on my small 2 channel shure field mixer is about -3 db with the resistor attached. Without it its measuring a hair above zero. Im geussing for +4 db I wont need it.


2nd problem is that I can't seem to get the Q bias to do a darned thing. Im setting it up like I have seen mentioned on Gyrafs site and in the 1176 manual. I saw someone talk about attaching DMM to the output pot but Im a bit confused about this one.

When a resitor take forever to creep up to almost spec on my DMM should I replace. A few of them are real slow others show their value immeadiatley.

If someone could enlighten me or direct me to a good post on the technique! It seems to pass audio well no problems yet although all its heard is a sine wave yet :green:

Thanks

William

 

[enthalpystudios]

hey william... do you have a 3k6 resistor directly on the VU meter??

If so, and you are using jakob's or mnat's pcbs, it's unnecessary as there is a 3k6 mounted on the meter switch board for just the purpose.

Also, when you talk about measuring resistors, is it slow while measuring resistors on the board, or just on loose resistors?

You can, and often do, get different measurements when measuring resistors soldered on to the board. If you're using the DMM to make sure the resistors are correct, a much better way is to print off a resistor color code chart and start checking against a print out of the pcb layout from the gyraf or mnats website.

Also, are your FETs socketed? I've had problems using non-machined sockets for the FETs. You may want to try wiggling the FET in place, and watch for correct meter movement....

but again, if you indeed have an extra 3k6 resistor in addition to the 3k6 that's on the meter switch pcb, that is most likely the problem.

Regarding the setup, I wouldn't even attempt it until the meter is behaving, but once you get the meter issue sorted out, the setup procedure should probably be done a few times.... honestly, once you've done it 7 or 8 times, you will have it down.

Also, 2 accurate AC millammeter or a dual trace scope is honestly the only good way i've found to set up the GR Tracking.

With a dual trace scope it becomes no problem... with just a single DMM, you will want to slit your wrists. At least I did anyway... it's really a very hands on experience.

Billy

how bout that, it looks like you're about 5 miles north of my hometown ;]

 

[W DeMarco]

Thanks Billy,

I do indeed have a resistor on the sifam but only put it there after I noticed the vu was pegged. I was hoping it was the problem solver. Guess not huh? So Ill remove and try again. I soldered the FET in directly. So its not mechanical, unless i roached it. The slow dmm reaction was ocurring measuring on board resistors.

Ill print a chart and go through them again.

I do have a dmm and a dual trace but lets wait like you said on the Q bias!

Last time I was in Kent I stopped in at woodsies where they had two Spectra 610's ridin low in a rack on the floor. We asked what they we're doin there and he said that they have been for sale on the floor for 10 years or something like that. I quess they we're the final pieces left from the old studio there. Get this he sold em both to me for 500 bucks!!

I love that town


William

 

[enthalpystudios]

man, i never saw those in there! i wouldn't have bought them, but i'd be proud of finding them, and i'd have asked to plug em in ;]

i honestly wish i could remember why my vu's pegged on my units... it happened just as you have happening, but i dont remember what fixed it for me.

what i do remember doing, however, is going through and checking every single resisitor with the chart on two units. and it solved something.....

and then i had the magic fet, that would begin to indicate GR on the meter when, and only when, a finger or metal probe was in close proximity to, but not touching, the fet.... it was some loose spot somewhere, no ground, something like that.... i think that may have been the socket i used.... i think i replaced the sockets and had much better luck.

if you dont decide to put some in, solder them high, so you can get in there and clip em quick n easy and replace.

I went through around 10 or 20 FET's, but i was attempted to stereo match... which ended up not working as well as i hoped ;]

but alas, i have two great working units here.... now to try this alternate input tranny i wound, find out what its made of ;]

with the qbias, first get your signal, something steady and sinuous, in the neighborhood of 850mV rms (multimeter) or 1.2 Vpeak to peak on the oscope. Approximately that ballpark. Plug the output of the g1176 into a daw input and meter in PT or something that works for you.... adjusting input and ouput, and get it to +1db on the DAW meter.

then, go ahead and and turn the qbias all the way down, counter clockwise. eventually, you'll get nothing.

then you can turn it up until you get 0db on the DAW meter.

Try and let the unit warm up for a good bit first, 30 mins at the least.