[flynhawaiian]

I am about to order everything and am curious what other parts besides the ones listed in the BOM that I need to purchase.  Seems like there are a few things missing.  Thanks so much

 

[jdkJake]

Kind of an open-ended question as a lot will depend upon what you envision as the final product.

You will need a case, input/output jacks, a potentiometer, hookup wire, various screws and stand-offs, an IEC power input (preferably with a fuse), a power cord, possibly terminal strips of some kind for the star ground, possibly crimp-style, shielded spade lugs (highly recommended for the power input and chassis ground to earth ground connection) and the tools to put it all together. You might want to have the parts for a ground loop isolator in case you should need it.

Take a look at the various builds pictured in the thread and put together your list.

 

[Cloud]

 
Hi all, Will like to seek some opinions on wiring up my EHHA.
 
Basically i am going for balanced set up. but i am going for "Dual Mono" balanced set up with 2 cases. 
 
Each case will house 1 x Transformer, 2 X EHHA Rev A boards and 2 X E12 circuit. The idea is that if i need single ended output, I will just need to power on one case instead of 2. 
 
I have attached a connection diagram and will like to seek help to check if everything is connected properly. I have omited the connections from transformer to boards as i dont think i will have trouble with that. 
 
I will be using a single neutrik combo output jack for both XLR and 1/4" connections. 
 
 

 

[jdkJake]

Don't forget the heater DC supply needs to be tied to star ground as well as the output ground of the main rail power supplies.

You may have to experiment a bit with the star ground point of the amp itself. In your drawing it appears you are attaching to star ground at the output point. You may find different (perhaps better) performance at the input point. You really have to try both and see which works better for you.

I trust you have seen this page:

http://www.cavalliaudio.com/diy/ehhaa/main.php?page=setup/setup

 

[Cloud]

Thanks jk,
 
yup i have read a few times on the wiring page. will try a few configuration to see which works for me. 
 
But in all the midst of excitement, i forgot to include my potentiometer. I guess 2 case balanced idea is hard to pull off.
 

 

[jdkJake]

Do you need a potentiometer? What will you be using for a source?

 

[jdkJake]

To complete the thought, you could always build a third box. The third box could provide either a passive or an active attenuation solution. Perhaps even include multiple input selection.

Something to consider.

 

[Sathimas]

I asked that some time ago already but got no real answer:
 
If I reduce the bias current - could I build the ehha with just 1.5inch tall heatsinks?
 
I don't know how hot they get, my case would have proper ventilation since the top
is almost completely open - there'd be holes in the bottom too of course.

 

[jdkJake]

If I reduce the bias current - could I build the ehha with just 1.5inch tall heatsinks?

I suspect the 1.5" sinks would run fine without having to reduce the bias point. The MOSFETs run hot, but not overly so. I put some measurements up with the 2" sinks earlier in the thread. Search back for those to help guide your decision.

The key take away with using larger sinks is margin. There is much less to worry about from a thermal standpoint using the larger parts which have to work far less to dissipate the heat.

Be aware of one key point though, the size gain of the smaller sinks, if that is what you are seeking, may not be useable. Depending upon the tube socket you use, the height of the tube can be the driving factor in terms of overall height. Of course, if you are going for a through the case tube design, then this is not so much an issue.

 

[Sathimas]

Thanks for the fast replay!
 
This is a quick shot of my current plan (design not final):
 

 
I plan to mount the tubes off-board so that I can use the 50mm high frontplates from hifi2000.

 

[Lil' Knight]

^ Looks nice! But somehow I have a feeling that it'd be hard to roll the tubes with that way of mounting.

My friend is building his EHHA and having a problem. I haven't seen his build so this is just a vague description.
One board powered up just fine. The other one, when the amp section is disconnected, the PSU's readings were all fine. However, when he connected the PSU to the amp, the LM337 blew immediately. The heater is fine though.

Any idea regarding this problem?

 

[Sathimas]

 
Quote:

^ Looks nice! But somehow I have a feeling that it'd be hard to roll the tubes with that way of mounting.

Thanks!
 
I quit tuberolling with my soha I - the differences where not big enough to convince me

 

[jdkJake]

My friend is building his EHHA and having a problem. I haven't seen his build so this is just a vague description.
One board powered up just fine. The other one, when the amp section is disconnected, the PSU's readings were all fine. However, when he connected the PSU to the amp, the LM337 blew immediately. The heater is fine though.

There is apparently a short somewhere on the amp board. Time to breakout a multimeter and the schematic and start the search.

If he posts some good pictures, the forum might be able to help isolate where the problem might be.

 

[sachu]

Quote:

^ Looks nice! But somehow I have a feeling that it'd be hard to roll the tubes with that way of mounting.

My friend is building his EHHA and having a problem. I haven't seen his build so this is just a vague description.
One board powered up just fine. The other one, when the amp section is disconnected, the PSU's readings were all fine. However, when he connected the PSU to the amp, the LM337 blew immediately. The heater is fine though.

Any idea regarding this problem?

 
 
Obviously the PSU is being loaded severely. Check to make sure the negative rail is not shorted to ground on the amp section.
 
check output MOSFET on the amp section. Check impedances between drain and gate.
 
Also, get him to measure the trim pot setting on the amp board. Make sure it is turned counter clockwise (if its a 1k trimpot, it needs to be at 1k when measured across the outer terminals.)
 
 

 

[jdkJake]

This is a quick shot of my current plan (design not final)

Looks exquisite!

I look forward to your final implementation.