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EHHA Rev A - Interest Thread - Page 5

post #61 of 1671
Quote:

Originally Posted by runeight View Post

 

The ground point for SE setup with the internal PS is the mounting hole in the back-middle of the board between the PS section and the amp. Grounding here minimizes PS noise getting into the ground plane of the amp section. In fact, will effectively elminate it.

 

But how about tying the two boards together?  I'm (over)thinking ahead to when you have two boards and two power supplies, with two ground points and then where do you tie the ground for volume and output ground. 

 

Quote:

If I were to make a two channel, fully integrated EHHA similar to the SOHA II I would definitely build in an e12 just to be absolutely safe. But, we may not need to do that here.

 


A two channel board with integrated power/heater supply would rock for building.  And then two boards would equal a fully balanced rig.

 

Maybe it would be dreaming, but then having the two channel board fit into a 1455T2201 for total ease of casework...

post #62 of 1671
Thread Starter 

LOL. You guys are merciless.

 

The measured DC offset swing on power up.down with cold tube heaters turned on with rails is a little over 1VDC. This is not so bad and if consistent across all builds might make an e12 unecessary. Although you'd have to think about 32R headphones some.

 

With two boards each with their own PS, then you use the ground posts in the middle as the star ground point, either by putting a standoff and screw through this point to the chassis or by using the ground terminal on the PS output block to wire to the star ground.

 

The input ground wiring goes to the IG terminal on the input block. Headphone ground goes directly to the star ground point on the chassis.

Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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post #63 of 1671
Thread Starter 

cobaltmute, you were right about the score line. It would have to be both on the top and bottom of the board in order for the board to snap correctly. I thought just the top would do.

 

But, if it's on the bottom too then it will cut the power planes.

 

Thinking on another solution. The easiest would be for you to wire across the terminal blocks for the on board PS.

Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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post #64 of 1671
Thread Starter 

double post

Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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post #65 of 1671
Quote:
Originally Posted by runeight View Post

cobaltmute, you were right about the score line. It would have to be both on the top and bottom of the board in order for the board to snap correctly. I thought just the top would do.

 

But, if it's on the bottom too then it will cut the power planes.

 

Thinking on another solution. The easiest would be for you to wire across the terminal blocks for the on board PS.


what are the actual dimensions of the board with and without a PS?  how about just leaving the PS intact with the amp portion and the builder has the choice to populate it or not?  i'm assuming making the PS separate would up the fab costs?

post #66 of 1671

What about a series of holes that makes it easier to cut the board into two?  It will affect the groundplane somewhat, but it should not be so bad.

 

But then again, jumpering across the cut-line is also a very effective solution.

post #67 of 1671
Thread Starter 

Making the PS separate would be very easy. That is, I would separate the power planes on the bottom so that the score lines don't cross an traces and you would connect the two board by wiring across the terminal blocks. The PS and amp would still be on the same board and this would be the same cost as paneling up mulitple boards onto a single board to get cost savings.

 

I'm going to think about crossing the cut line, but I think the answer is going to be wires.

Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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post #68 of 1671

I am considering building an EHHA very soon.

 

When do you think this revision will be ready?

 

I kind of want an external power supply for some reason.

I am not sure, but the external power supply seems more versatile and can be used in more situations.

But, I've never had one, so maybe I'm wrong.

 

 

Is there any advantage to building an EHHA Rev A vs the previous EHHA version in the case that either versions would be using a sigma22?

 

Thanks

post #69 of 1671
Quote:
Originally Posted by runeight View Post
I'm going to think about crossing the cut line, but I think the answer is going to be wires.


sounds like a win.

post #70 of 1671
Thread Starter 
Quote:
Originally Posted by nullstring View Post

I am considering building an EHHA very soon.

 

When do you think this revision will be ready?

 

I kind of want an external power supply for some reason.

I am not sure, but the external power supply seems more versatile and can be used in more situations.

But, I've never had one, so maybe I'm wrong.

 

 

Is there any advantage to building an EHHA Rev A vs the previous EHHA version in the case that either versions would be using a sigma22?

 

Thanks


The Rev A EHHA is just a little bit faster. The main change was putting a PS on the board so you don't need a separate external PS. If you are planning to use an external PS with either amp I would say there isn't a huge benefit to waiting.

 

I'm going to wait for a bit more discussion and some folks to get back from vacation and for further conversations with Jeff Rossel before we decide when to make the new version available. So, I don't know yet.

Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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post #71 of 1671

Alex,

 

I'm not sure if you mentioned this before, but, do you know if on the prototype for Rev A. that has already been built, if the builder is running AC or DC heaters, and if he/she is running a separate transformer for the heaters or is running them off additional secondary windings?

 

Pabbi1 already mentioned DC heaters in this thread, but I'm not sure it was really addressed.

It seems like most of the EHHA-1 builders have been running DC heaters (with a separate transformer) - I believe Smeggy has this only EHHA that I know of that is running AC heaters).

 

Since the power-supply is being completely redesigned anyway, it might be beneficial to discuss the separate heater supply options?

 

What are everyone's preferences?

post #72 of 1671

double post


Edited by stixx - 8/17/10 at 11:42am
post #73 of 1671

I'd prefer DC heaters (regulated) in an amp of this level...parts count is low and not much real estate needed... just the transformer or a suitable secondary (when going custom).

post #74 of 1671

I'd prefer dc for the heater voltage, as well.

post #75 of 1671

yes, with this amp especialy please onlyy use DC heaters..There is an appreciable improvement overall in doing so.

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