[BUILD] 1176 Rev A - Back to the beginning...

[Biasrocks]

I would suspect the power transformer not giving enough juice.

Have you monitored the power supply to see how it's behaving?

Mark

 

[0dbfs]

The 30V output on the PSU is dropping down to 10V, 15V, 25V etc in time with the thumping... It takes maybe 30 seconds after connecting the 30V to both boards for this to start.

I am using the 30VA toroid from Avel Lindberg model # Y236107 to power the two compressors via the stand-alone PSU board

Here:
http://avellindberg.com/transformers/y23_range_specs.htm

Doubling the secondary amps rating using the Y236306 would take care of it if that is the issue.

I wonder if there is a way I could parallel the secondaries of the PT to provide double the amps and supply both the 30V and -10V side of the PSU?

Does anybody have a model number or ratings for the PT that they have used successfully in a dual unit with the stand-alone PSU board? I could measure the draw on the secondary used for the 30V side of the PSU to see if it would exceed the ~0.5A rating on the Y236107.

Best,
jonathan

 

[Stagefright13]

I used the Y236207 on all my 1176 builds. Even the single ones. They are cheap enough. And are discounted when you buy 2. Not sure if that is your problem tho...

 

[evilcat]

Speaking of power transformers, does a 30 VA 2x24 V tran' enough ? Or should I take a 2x30 V one ?

Thanks

Ben

 

[0dbfs]

Not sure about the 2x24 but the 30VA 2x30 works great with a single channel. Me thinks the 3+30 50VA is the way to go with a dual channel unit like stagefright mentioned.

If you have the 2x24 give it a try it'll prolly do.

Best,
jonathan

 

[evilcat]

Thanks ! I'll go for 2x30, and it's for a single channel.
Sorry if it's a stupid question (and I'm sure it is !!!) but the voltages will be +30 and -10 V anyway, isn't it ? The PSU section modify the voltages whatever transformer you put in front of it ?

 

[0dbfs]

the voltages will be +30 and -10 V anyway, isn't it ? The PSU section modify the voltages whatever transformer you put in front of it ?

That is correct.

The diodes in the PSU section will rectify the AC from the PT to DC, the caps will smooth it, and the regulators will bring it down to the desired voltages. The regulators do have limits but the 30+30 is within those limits. Read up on the datasheets for those parts. The stand-alone PSU that mnats included is pretty cool, flexible, and easy to tweak for different needs if you are using the on-board PSU, you can use the extra PSU board for a variety of purposes.

Best,
j

 

[muffy1975]

hey,

i find the internal on board PSU for the RevA does not give me the -10v, more like 8.9V. I have to use the external PSU that MNATS sells for this project.

Alot of people have noticed and low figure on the negative rail with the REV A.

Michael

 

[0dbfs]

I've got a -9.7 and +30.3 using fixed resistors on the external PSU and intend to swap out the fixed resistors with the trimmers to get it exact when I open it back up for service. It's on my RevA honeydew list.

ATM, mine is compressing so I can use it until I get some parts:
- Still need a larger PT for dual channel unit.
- Need some more 3708's to swap out and match Q12/13 in an effort to get my GR meter working.
- Need to order matched 5457's from Mike to ensure that the GR meter and audio compression are matched.

I have noticed that the 20:1 setting distorts fairly quickly on both of my channels. The attenuator range is pretty small for useful limiting on that setting (unless I want that sound). Has anyone else noticed this or is this normal for the RevA?

Best,
jonathan

 

[ChrioN]

2x24vac is totally ok. I've used that in all my builds so far.

 

[evilcat]

That is correct.

The diodes in the PSU section will rectify the AC from the PT to DC, the caps will smooth it, and the regulators will bring it down to the desired voltages. The regulators do have limits but the 30+30 is within those limits. Read up on the datasheets for those parts. The stand-alone PSU that mnats included is pretty cool, flexible, and easy to tweak for different needs if you are using the on-board PSU, you can use the extra PSU board for a variety of purposes.

Thank you very much for this quick lesson !

 

[portix]

I couln't find any other post about this:
The resistors of the ratio board of the hairball kit are numbered from 1 to 10 and it don't match with the BOM numbers.
So what are the good values?

Regards,

Marc

 

[phatmateo]

http://hairballaudio.com/docs/FET_Compressor_PCB_Board_Info_V2.pdf

 

[Echo North]

http://hairballaudio.com/docs/FET_Compressor_PCB_Board_Info_V2.pdf

I need to find a better place to post that.  It's kind of hidden.

I'll be doing a major "Reference Documents" update soon that will contain a lot of useful build info.

Mike

 

[portix]

Thx

 

[phatmateo]

Mike, you are making it too easy!!!! I'll post pictures of my completed rev D build with everything hairball soon

 

[Echo North]

Mike, you are making it too easy!!!! I'll post pictures of my completed rev D build with everything hairball soon

Cool!

I was thinking of adding a "Completed Builds Gallery" to the site as well.

Mike

 

[ethervalve]

I was thinking of adding a "Completed Builds Gallery" to the site as well.

Mike

GREAT idea!

 

[phishman13]

i fully agree!

you're more than welcome to link to my completed unit!

http://www.groupdiy.com/index.php?topic=37204.0

Or I'll send ya some pics to post on the page.  Everything you sold at the time that could be used for the rev A is in there!

 

[marktokach]

I have 2 rev a ver 1.1 boards that came with 4 boards each. Looks like there are 2 power supply boards that needed to be snapped off the main board as well as the other 2. I see on mnats site that there is a ver 1 and ver 1.2 patrs list. Not sure which to use because mine says ver 1.1. My main questions are; can I use just one of the power supply boards, that are different from the new double sided one, to power a dual 1176 rev a, or do i need to get the new one, and what version of parts list do I use? TIA, Mark.

The psu board reads; PSU Mnats 26.01.09