[sachu]

Quote:

Originally Posted by wiatrob /img/forum/go_quote.gif Well, its supposed to be fun! But there can be a few frustrating moments: I started to troubleshoot my broken EHHA board, hooked everything up, checked all the wiring, and still managed to reverse +/-30V. It's REALLY dead now...

aah man...that sucks dude..

 

[smeggy]

Did it play all your music backwards and tell you to do evil things?

 

[TimJo]

Could one of you guys measure a EHHA board and post the dimensions. I don't see the board size on the website, and I'd like to start planning the casework...

Thanks.

 

[wiatrob]

3 1/2" x 4" from memory... Can check this eve...

 

[runeight]

Very close: 3.6" x 4.2"

 

[TimJo]

Thanks...

 

[DoYouRight]

From help by Sachu on deciding, I think the EHHA will be my Tube amp to compliment the B22 when I finish it. Very excited about this.

Deciding to go DIY was very smart considering I can build a B22 for the same price as a Compass AMP/DAC is really frustrating but good learn

 

[smeggy]

Yay, same as me. Beta22 and EHHA

Well, along with the CTH and others..

 

[TimJo]

Well, I originally thought I'd just go with AC heaters, but now I'm thinking about building a DC regulator, especially after reading Don's advice.

Quote:

Originally Posted by dBel84 /img/forum/go_quote.gif just my 2c AC heaters can be used but because of the nature of this amp , the proto team even considered an S11 as an option for the heaters and not overkill . I would personally look at low noise DC supplies as default. ..dB

I've been looking at the options and in reading what Morgan Jones had to say about heater supplies, he brought up the topic of cathode poisoning. Since it sounds like the recommended startup sequence on this amp is to preheat the cathodes before B+ is applied, it seems like cathode poisoning may be relevant here. He lays out a fairly simple heater supply that uses an LM317T regulator and Schottky diodes, but is configured to output ~4 V on standby, and then kick in to 6.3 V when B+ is applied. He says that running the heater's at 63% of full power will reduce any ill effects during warmup.

Any thoughts on this, or practical experience in any other tube amps?

 

[smeggy]

I'll be using a plain AC heater until I get time to put a regulator together. I have the parts, just no time or inclination right now. I'll get to it one day though.

 

[adamus]

I really wouldnt bother with the low voltages on offer here.

Quote:

Originally Posted by TimJo /img/forum/go_quote.gif Well, I originally thought I'd just go with AC heaters, but now I'm thinking about building a DC regulator, especially after reading Don's advice. I've been looking at the options and in reading what Morgan Jones had to say about heater supplies, he brought up the topic of cathode poisoning. Since it sounds like the recommended startup sequence on this amp is to preheat the cathodes before B+ is applied, it seems like cathode poisoning may be relevant here. He lays out a fairly simple heater supply that uses an LM317T regulator and Schottky diodes, but is configured to output ~4 V on standby, and then kick in to 6.3 V when B+ is applied. He says that running the heater's at 63% of full power will reduce any ill effects during warmup. Any thoughts on this, or practical experience in any other tube amps?

 

[smeggy]

I measured my heater transfo and it seems right on the mark and it lit the tubes fine so I'm not gonna fret over it. Alex does specify either way will do.

 

[sachu]

Quote:

Originally Posted by smeggy /img/forum/go_quote.gif I measured my heater transfo and it seems right on the mark and it lit the tubes fine so I'm not gonna fret over it. Alex does specify either way will do.

You are sure to have noise on the outputs this way. I did on mine and with orthos that too.

 

[looser101]

Quote:

Originally Posted by sachu /img/forum/go_quote.gif You are sure to have noise on the outputs this way. I did on mine and with orthos that too.

Try connecting a small cap (.1uF) to ground on one of the heater pins. Also make sure heater leads are tightly twisted and not near any signal wiring.

x2 on Adamus comment. My understanding is that delaying the B+ is only necessary at much higher voltages.

 

[sachu]

Quote:

Originally Posted by looser101 /img/forum/go_quote.gif Try connecting a small cap (.1uF) to ground on one of the heater pins. Also make sure heater leads are tightly twisted and not near any signal wiring. x2 on Adamus comment. My understanding is that delaying the B+ is only necessary at much higher voltages.

yeah the way i have my heater wiring laid out, they pretty much go past the signal wires..hence i went with a LDO reg DC supply.