A couple layout questions

[surfsup]

I'm working on a build and have a couple layout questions I think I'm close here. The resistors on the Ptubes and PT/OT/choke runs are still missing...and the MV is a dual gang pot I'm sure you guys knew that though.

Here's my questions:
Where should I go with the speaker ground, the IEC? or star?
The ground for V2's cathode runs underboard but also under the dropping resistor, is this okay?
Are the trannies aligned in the correct fashion (I will still headphone it)?
Does anything scream out at any of you to change?

First image is no iron, second has the iron on it...
[img675]http://chicagocadcam.com/ChrisHahn/schem/x10L_1.jpg[/img][img675]http://chicagocadcam.com/ChrisHahn/schem/x10L_2.jpg[/img]

[selloutrr]

Where should I go with the speaker ground, the IEC? or star?


The IEC should be alone and not share with other connections.

I wouldn't bring the speaker out all the way back to the star.
You should be able to short to the chassis, try bolting it to a socket bolt, or using different type of jack that is not isolated.

You might need / want to consider making a grounding buss for the pots and leading them to star ground.

The transformer layout should be fine they may need to be spaced apart a bit more?

Happy building!

[surfsup]

Sellout thx, i see the tw amps ground stuff at the iec and have seen it before on others. I was concerned about a long run? Guess its ok.

The gnd run under the board directly under the b4 dropping R is okay?

I can move the ot over a bit but that will:

1- push the choke further away, is that a prob?
2- the secondaries will have to "go around" the ot primaries to get to the speaker jacks. Not an issue?

Another concern i have is the location of the cathode RC off the Ptubes. Is that okay? I figured i could ground them to their cap like i drew. EDIT, whoops just noticed they are grounded to the star, but I would ground them to the cap to the right.

[selloutrr]

The gnd run under the board directly under the b4 dropping R is okay?

I'm not seeing a ground run (green line) I would assume as long as your board is elevated and the ground run hugs the chassis you should be fine.

If you are refuring to the dashed line - yeah no worries people do those runs all the time.

I can move the ot over a bit but that will:

Before you move anything It's hard to tell actual spacing since the amp is not noted to a scale. I like to have at least 1" between my iron and it looks like you alternated the plates so you should be ok.

Another concern i have is the location of the cathode RC off the Ptubes. Is that okay? I figured i could ground them to their cap like i drew. EDIT, whoops just noticed they are grounded to the star, but I would ground them to the cap to the right.

I like to keep my power grounds and audio grounds seperate. also the shorter the better.

[surfsup]

Okay great thanks. The PT/OT had 0.661 between them I changed that to 1" between those and the choke and OT. I will do the headphone trick before drilling anyway. I figure its probably more important to do that even if it adds an extra inch to the lead lengths.

I will also keep the Ptube RC straight to the star then. Thanks for that tip!

Thinking about that, I grounded the V1 like I have diagrammed here on a different amp and it really (SE) helped the hum. Basically filter cap, cathodes and input all at a star by the input. Think that's okay? Thanks so much for answering, btw.

[tonewood]

Here's my questions:
Where should I go with the speaker ground, the IEC? or star?

I'm more used to looking at schematics than these layouts but I don't see NFB from the OT secondary or spkr terminal. If there is no NFB, I don't think you should ground the speaker. Just run the OT secondaries out to the isolated jacks. If there is NFB, run the ground near to where the NFB returns to.

[XgamerGt03]

I'm more used to looking at schematics than these layouts but I don't see NFB from the OT secondary or spkr terminal. If there is no NFB, I don't think you should ground the speaker. Just run the OT secondaries out to the isolated jacks. If there is NFB, run the ground near to where the NFB returns to.

That can cause some issues in an amp if you don't ground the speakers even without NFB. Its generally accepted that you should always ground the speaker jack, NFB or not.

[selloutrr]

The best advice to keeping your ground noise at a minimum.

Meter for Ohm load to ground and try to get 0.01ohms or lower a solid grounding makes a huge difference. It's as important if not more so then lead dressing, because if the connection is not solid who cares how nice it looks.

even if you use an isolation jack make sure your speaker ground is grounded and switching. If you turn the cliff style jacks 90 degrees you can use one buss wire for all grounds.

[Ken Moon]

Meter for Ohm load to ground and try to get 0.01ohms or lower a solid grounding makes a huge difference. It's as important if not more so then lead dressing, because if the connection is not solid who cares how nice it looks.

If you're connecting a typical solder lug to the chassis, take a minute to clean the surface that will contact the chassis. You can do this by rubbing it with a clean pencil eraser. A small layer of corrosion can keep it from making good contact.

The same on the chassis side - clean it and at least scuff it up a bit with scotchbrite or sandpaper, to get the natural corrosion layer that 'grows' on the aluminum or steel chassis off.

The very best connection is made between two polished surfaces - if you clean and polish two metal surfaces and press them together tightly, the pieces can sort of 'weld' together at the molecular level - it sounds counter-intuitive, especially since scuffing the surface also works ok and is usually recommended - but it's freaky to see how tight a bond you can get between polished surfaces.

The reason for this is that when two very flat surfaces are brought into very close contact with each other, this allows an interchange of electrons between the atoms of the separate surfaces, which creates an attractive molecular force. The phenomenon is most apparent when 'wringing' metal calibration gage blocks.

Getting off on a pretty pretty obscure tangent I guess...

[tonewood]

That can cause some issues in an amp if you don't ground the speakers even without NFB. Its generally accepted that you should always ground the speaker jack, NFB or not.

Can you explain the issues? I haven't had problems with it yet, although my amps aren't super high gain.

I may be reading it wrong but I think this makes sense to me & I think he is saying you don't have to ground the speaker if it has no NFB??

http://www.aikenamps.com/StarGround.html
see the "What about output jacks" section

Well, this guy says to return it to the star.
http://valvewizard2.webs.com/Grounding.pdf

Can anyone explain the issues?
Thanks

[surfsup]

From the valvewizard pdf:

http://valvewizard2.webs.com/Grounding.pdf

He references page 10 "CMRR". What does that acronym stand for?

[Colossal]

He references page 10 "CMRR". What does that acronym stand for?

Common Mode Rejection Ratio

[ToneMerc]

From the valvewizard pdf:

http://valvewizard2.webs.com/Grounding.pdf

He references page 10 "CMRR". What does that acronym stand for?

It's amazing the things that you never forget. Back in dark ages (pre MTV) I remember an instructor writing those letters on the board just before he gave us a problem to solve.

TM

[Ken Moon]

From PaulRubyAmps.com:

"Finally, you need to ground your OT secondary. I'm often surprised to see folks online suggesting otherwise. First and foremost, an ungrounded OT secondary means your speaker lines will rise to B+ in the event of an OT fault. That's a safety issue and is not acceptable. Second, if your amp has NFB the OT secondary must be grounded at your power amp star point for proper ground referencing. Finally, even if you don't have NFB an ungrounded OT secondary will be capacitively coupled to the primary and can thus have a high AC voltage swing. This high AC voltage swing can make its way back to the input path and cause squeal. And, the OT core should be grounded to the chassis via the mounting bolts."

[tonewood]

From PaulRubyAmps.com:

"Finally, you need to ground your OT secondary. I'm often surprised to see folks online suggesting otherwise. First and foremost, an ungrounded OT secondary means your speaker lines will rise to B+ in the event of an OT fault. ."

Thanks Ken! This alone is good enough for me to make sure I ground my secondary.