Re: Retired:Symmetrical FET
« Reply #160 on: July 08, 2016, 10:41:23 AM »
Brilliant. Many thanks Gustav.

Ill have a look into getting the parts ordered soon, will be a good next project. As soon as i get a vco calibrated...

Cheers, all the best
Ben

 :)


Re: Retired:Symmetrical FET
« Reply #161 on: July 15, 2016, 07:42:38 AM »
I checked for AC on the DC rails, and there was nothing. I was really hoping that would the culprit.

I noticed I was drawing the lights for everything from the toroid directly. Thats another possible difference.

If this is some easy fix, I have some time the next few weeks. I could redraw the schem and give  a single sided/self etch version a shot...

Gustav

Greg S.

Re: Retired:Symmetrical FET
« Reply #162 on: December 24, 2016, 01:33:12 PM »
Hi Nick ,thanks for information!  I am close to build up this project and I ask myself if there is a way to  get rid of the noise problem on the  original pcb without an additional psu pcb.

Whats the problem with the onboard psu? It looks like a standard textbook implementation of a bipolar psu to me...

Any hints?

cheers  8)

Take a look at the paper of an LM317 and LM337.
They got -60dBV ripple and noise at the out.
You may get ca 80dBV by adding an 100uF/25V Elko Cap across the Adjustment Resistors in the PSU!
Try it out


Re: Retired:Symmetrical FET
« Reply #163 on: December 26, 2016, 08:23:36 AM »
Take a look at the paper of an LM317 and LM337.
They got -60dBV ripple and noise at the out.
You may get ca 80dBV by adding an 100uF/25V Elko Cap across the Adjustment Resistors in the PSU!
Try it out

I think I tried this with no change on this.

Maybe caps by the BD139/BD140 would solve all!?

Still retired, may see if I can do changes and bring it alive for 2017 if theres any interest and solutions.

Gustav

Greg S.

Re: Retired:Symmetrical FET
« Reply #164 on: December 26, 2016, 01:45:36 PM »
I'm still working at this project!

Perhaps you add a Servo at the Output-Stage?
You should add some Resistors for Biasing the BD139/BD140!

Re: Retired:Symmetrical FET
« Reply #165 on: December 28, 2016, 08:32:44 AM »
 ;) Go Gustav, like your work.
www.kontrast.in - I make websites and stores online.

Greg S.

Re: Retired:Symmetrical FET
« Reply #166 on: December 30, 2016, 04:49:20 PM »
I spend some more hours on that project, here is what you may do for improvements:
First I have to mention, that I got different Schematics and Layouts of these Projects.
I do not know how much Revisions Gustav made, so some Names might be wrong!

Perhaps Gustav might send me the Final Version! THX

0 PSU
Replace the On-Board-PSU and Replace ist by something less noisy, e.g. 7815, 7915 Regulation with some LOW-ESR Caps behind the Regulators

1 Input section:
R1, R2, R3, R4, R5         10k > 1k
less Johnson Noise!

2 Input Section
add 100k to GND at the Input
e.g. Pos-Left, Neg-Left, Pos-Right, Neg-Right

3  Input VOL POT
R40/R66    1k  >  ALPS RK27112 10k log

3 Output Driver
C24, C25, C32, C33  100uF/25V  >  unused

4 GR-Meter-Tracking
TL074 > OPA4131 or MC33079

5 Magnetic Shield
I added a Round MU-Metall Schield to the Power-Torroid and at the Top and Bottom Case too Self-addhesive Mu-Metall!
There should be no space between those Mu-Metal-Shields!

6 Zener
ZD10 > 1N4148

7 Output Driver
D1, D2, D3, D4, D9, D10, D11, D12 > 1N4148

8 Lundahls Output
Add 1k parallel to the Outputs of the Lundahls between Pos and Neg

9 OPA's
NE5532AP seem to be the Best,
I tried OPA2134 and LM4562, Values were worser!
Didn't check MKP's as replacement for the 100u Caps following at the Input stage

10 Pots in General
I simply used ALPS RK27112
Input      POT 10k log
Output POT 100k Log
Attack  POT  20k Log
Release POT 1M Lin

Those ALPS got Differences up to 20%, If you want real StereoKompression, you will have to match 'em out!!!

If you want extended Release times, try to change R52 via Switch or Relay

11 Fet's or NPDXXXX
I used BF245A, matched 'em on my own,
http://www.masonaudio.org/diy/comp1176

Result:
At 0dBu Input and Output, I got -94dBu Noisefloor on both Channels
-3dB: 9Hz, 100kHz

Good Luck

GrG
« Last Edit: January 02, 2017, 05:12:05 PM by Greg S. »

Zebra_PD

Re: Retired:Symmetrical FET
« Reply #167 on: April 11, 2018, 05:06:30 AM »
Hi!

Im going to attempt to build a 1178 klon in a UREI 353 case. Also got a hold of a NOS  1178 frontplate on ebay for the build.

After some research I believe that this design is the best starting point for my project.

The 353 shares some similarities in design and was hoping to save/use as much as the original UREI components as possible. Will make my own build thread when I have sourced most of the parts needed to start the build.

But I have some questions Im hoping you Gustav or perhaps some one else of guys who have made this build could help me answer.

1. Is it possible with this pcb design to use the original output transformers (12614)  from the 353 for this build as well? Looking at the original schematics the 353 and 1178 seems to share the same output transformer. On a similar issue, is it possible to use the same original power transformer (16-12261) for this build?
 
2. Is it possible to use the same 4 gang inter-locking switch bank as for the 1176?
Like the one from Hairball (http://www.hairballaudio.com/catalog/parts-store/switches/meter-switch-bank-assembly)
or mic and mods (https://www.micandmod.com/hardware-parts/1176-power-ratio-switch-bank-assembly.html#/39-pcb_kit-yes_2_euros)

Or do I need a different one? What was the reason this design uses knobs instead of swiches?

3. Do you happen to have some of the PCBs left and/or planing to print some more?

4. Otherwise is the current MS76 possible to use with the my output transformers (12614) and power transformer (16-12261) to get the same  stereo 1178 sound? I guess since I read in the officiell build thread for the MS76 that is based on the G1176 design but lacking the input transformers similar to the late silverface/1178 design? 

« Last Edit: April 11, 2018, 06:21:55 AM by Zebra_PD »
"The looks is half the sound"
----------------------------------------------------------
My company:
www.zebrastudios.se

Re: Retired:Symmetrical FET
« Reply #168 on: April 12, 2018, 02:23:19 AM »
1. Is it possible with this pcb design to use the original output transformers (12614)  from the 353 for this build as well? Looking at the original schematics the 353 and 1178 seems to share the same output transformer. On a similar issue, is it possible to use the same original power transformer (16-12261) for this build?

You can use the output transformer (do you have two?), and we would need to know whats on the secondaries of the power trafo to know. It won't make any difference, though.

You can also use them for something else - they are not tied to these particular applications.

 
2. Is it possible to use the same 4 gang inter-locking switch bank as for the 1176?
Like the one from Hairball (http://www.hairballaudio.com/catalog/parts-store/switches/meter-switch-bank-assembly)
or mic and mods (https://www.micandmod.com/hardware-parts/1176-power-ratio-switch-bank-assembly.html#/39-pcb_kit-yes_2_euros)

Or do I need a different one? What was the reason this design uses knobs instead of swiches?

It uses switches, just a different type of switch - comes down to simple availability and convenience.

3. Do you happen to have some of the PCBs left and/or planing to print some more?

Sorry, no.

4. Otherwise is the current MS76 possible to use with the my output transformers (12614) and power transformer (16-12261) to get the same  stereo 1178 sound? I guess since I read in the officiell build thread for the MS76 that is based on the G1176 design but lacking the input transformers similar to the late silverface/1178 design?

The best answer I can give is, you can try and report back.

Gustav

Zebra_PD

Re: Retired:Symmetrical FET
« Reply #169 on: April 12, 2018, 06:31:48 AM »
You can use the output transformer (do you have two?), and we would need to know whats on the secondaries of the power trafo to know. It won't make any difference, though.

You can also use them for something else - they are not tied to these particular applications.

 

It uses switches, just a different type of switch - comes down to simple availability and convenience.

Sorry, no.

The best answer I can give is, you can try and report back.

Gustav
[/quote]

Thank a million for your reply Gustav!!

The power trafo ( 16-12261) is 2x18v and has the same ID number in both the 535 and the 1178. Someone also suggested me to also keep the volt regulators from the 353? Hence I have read in this tread that some people having problem with the power supply in there build perhaps i might be a good idea to keep as much as possible from the power part of the 535?

Yes I have two original output transformers (12614) since the 353 is a M/S unit with both mono and stereo input and and outputs :)

Well thats to bad that you didnt have any spares or planing to print some more..... Im trying to learn how to use Eagle haven't  been able to import the PDF version of your schematics and/or board design yet. I know it is asking a lot but would it be possible for you to share/sell a copy of your gerber file? If so you can reply to the email I sent you Gustav using the contact form on the PCB Grinder site.



"The looks is half the sound"
----------------------------------------------------------
My company:
www.zebrastudios.se


Re: Retired:Symmetrical FET
« Reply #170 on: April 12, 2018, 07:50:33 AM »

The power trafo ( 16-12261) is 2x18v and has the same ID number in both the 535 and the 1178. Someone also suggested me to also keep the volt regulators from the 353? Hence I have read in this tread that some people having problem with the power supply in there build perhaps i might be a good idea to keep as much as possible from the power part of the 535?


I think trying to add some decoupling caps around the transistors would have a bigger impact, and I am sorry, but I dont have the gerbers for the project anymore.

Gustav

Zebra_PD

Re: Retired:Symmetrical FET
« Reply #171 on: April 12, 2018, 03:44:46 PM »
I think trying to add some decoupling caps around the transistors would have a bigger impact, and I am sorry, but I dont have the gerbers for the project anymore.

Gustav

Thank you for the advice with the decoupling caps :)

Well that's to bad but writting a schematics Gerber file from scratch will prob be very educating and will have to learn it someday anyway.

Now I will stop flouting this retired post. Will keep posting in my own drowing board post. https://groupdiy.com/index.php?topic=68767.0

Hope it's OK to post any future modified version of your original schematics in that post for feedback and help from the forum? Will of course credit you as original designer in all the files. If not just please let me know Gustav.
"The looks is half the sound"
----------------------------------------------------------
My company:
www.zebrastudios.se

Greg S.

Re: Retired:Symmetrical FET
« Reply #172 on: November 19, 2018, 07:28:26 AM »
Hi Gustav, will you ever relaunch this project?

Re: Retired:Symmetrical FET
« Reply #173 on: December 04, 2018, 07:00:57 PM »
Hi Gustav, will you ever relaunch this project?

Hey Greg!

I consider it an earlier step towards this, so not likely

https://pcbgrinder.com/index.php?route=product/product&path=59_61&product_id=64

Gustav