All things G1176 - the new "repost" thread.

[Andrew]

Okay, I lowered the Qbias and it eliminated most of the harsh distortion issues. I'm still concerned about the ratios. If Q1 is biased in it's linear region of operation and all my resistors are right, then I'm assuming the ratios will work correctly?

Thanks,
Andrew

 

[gswan]

Yes, but don't expect them to be too accurate, we're in the analogue world now where drift and tolerances play a big part. So you might get 5:1 on the 4:1 setting, or 12:1 on the 10:1 setting. If you have two units the ratios probably don't track identically either. If you measure them you'll see.

 

[gswan]

Distortion and incorrect compressor operation is definitely how I would describe what I'm hearing, but I'm almost 100% sure that Qbias was set correctly, and my ratios are correct at this setting.

Is it possible that some flux kicking around in the high Z area of Q1 and the 2M resistors could be causing distortion?

Unlikely. It's more likley that you have an incorrect component value somewhere. Put a sine wave through the unit and measure it with a CRO, both with and without GR switched on. Distortion will be clearly visible if you compare the input and output waveforms.

 

[onlymeeee]

Hi, I am building mnats J board and would like your opinions on output transformer.

I really like the sound of the silver Urei 1176 (blue logo, red push button) (rev H?)

To get this sound, am I better off getting a replacement B11148 from here:
http://www.studioelectronics.biz/sunshop/index.php?l=product_detail&p=1166
rather than get the LUNDAHL LL5402

 

[gswan]

The sound of the unit comes from more than just the output transformer.
Even for the same model you can get many different sounding units.
Are you sure this transformer is compatible? What are its specifications? How do these compare with the LL5402 specs?

 

[onlymeeee]

Not sure yet if it's compatible with the mnats board.
I just know that it is the model used in a G rev.
Ed Anderson's posted some info about it (B11148) before.

Not sure how different the G rev and H rev sound? I think I normally use H revs and they use a 163-12614. (Any comments on sound differences?)

(Ps. Is there any appearance differences between "G" and "H" revs. or are they both the 'silver faced, blue logo, red push button'

 

[Echo North]

http://mixonline.com/mag/audio_revision_history/

Rev G (production dates unknown, serial numbers 7053-7651) replaces the input transformer with a differential amplifier. (Op amps lowered manufacturing costs and were very popular solutions for audio manufacturers at the time.)

Rev H (production dates unknown, serial numbers 7652 and above) changes the front panel to silver.

 

[onlymeeee]

Thanks, just seen that. So it's definately the H rev I like.
So the only difference inside is the transformer change?
Has anyone had experience with both a G and H? I assume there's a difference in sound.

Just weighing up the options of either a Lundahl, the replacement B11148.  Has anyone used the replacement B11148 from the link above?

 

[Terby]

Hi,

I have used the B11148 in my (mnats) G1176 to 1176 Rev F conversion (included UTC input and T-Pad, posted somewhere here) It sounds great, afaik I had to adjust the output termination resistor to ~ 600 ohms to get a linear frequency response.

  Andreas

 

[onlymeeee]

Cool, did you get a used one or the remake?
Is it R84 1k resistor you changed?
How have you wired it, as I believe they wired it differently for US and Export. (10db gain reduction)

EDIT: Actually It's the 16-11148 that has that option. which is used in the G.
The B11148 is used in the F
The 163-12614 is used in the H

 

[Terby]

It's a remake, the same as in the link above (also used in the LA3-A) I don't remember if the resistor is R84, it's the one after the transformer on the PCB (between pin 2 & 3 on the output XLR connector, not on the original Urei schematic)

  Andreas

 

[onlymeeee]

Ah, I think I see the resistor you mean.  It's a 1k(r84) on the G schematic but absent on the F schematic.

 

[microc]

Hi,
The output signal from my 1176 i balanced +4dB right? I wish to connect with balanced jack -10dB; because that what's my AD converter uses. Any body build an 1176 or simulare with both -10dB and +4 dB signal ? Or any moduls I could build in ? ???
thank you for your time "thumb"

~Jens

 

[gyraf]

..just turn down output level..

Jakob E.

 

[skal1]

an this oep xformer be used for ip/op { A262A6E} here is the data on it can some one  help please


http://radionics.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=2106431#header

theses are on evilbay just need to if they will work  for ip/op..

regards

ska1-2

 

[skal1]

sorry for bump but i need an answer time running out on bid.

Thanks in advance

regards

skal1

an this oep xformer be used for ip/op { A262A6E} here is the data on it can some one  help please


http://radionics.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=2106431#header

theses are on evilbay just need to if they will work  for ip/op..

regards

ska1-2

 

[skal1]

Has anybody used this A262A6E for ip/op in the 1176 before let me know iff some one has.


regards

skal1

 

[Kingston]

I read the whole thread (and a few other related ones) and thank you all for the vast amount of various help here.

Couple of questions remain, since I'm just about to order transistors.
There are some differences with data sheets here I'm not familiar with as I've been a tube guy this far.

BD 135-10: NPN 45V 1,5A 8W B:60-160 TO126

and

BD 135-16: NPN 45V 1,5A 8W B:100-250 TO126

What is that B value, and does it make a difference in this project?

about the corresponding BD139.. I guess I don't need the NPN 80V here and 45V is plenty?

about those BC107. I see there are BC107A, BC107B and BC107C available with the only difference being the pinout. What is the correct one for the mnats PCB? Should I be able to know this just by looking at the PCB?

I'm very new to transistors.

Mikko

 

[gyraf]

B = Hfe = raw current gain.

To compare, look up data sheets on the transistors originally used - as well as the new ones.

http://www.datasheetcatalog.com/

Jakob E.

 

[Kingston]

Thanks.

I'll try to figure out the BC107 pinouts from there as well.