[Ferrari]

Quote:

Originally Posted by AffeX /img/forum/go_quote.gif ... I will connect the two sides of this power regulator in parallel to the 12V, and set output to 6,3V. Any comments on this would be most welcome. ...

It's not a very good idea to use 12V secondary voltage to make 6.3V DC.
The heatsink will get unnecessary hot, even without load.
Remember that the voltage after the rectifier bridge is ~16V - 17V.

 

[ujamerstand]

Yes, the mute function protects the headphones, but not the circuit. Would turning on both the heater and the circuit on at the same time be detrimental to the circuit? I mean, would the transistors blow up if I don't wait for the tube to heat up before feeding power into the amp? I hope I am expressing myself clearly, it just seems like the extra complexity is not needed.

 

[ujamerstand]

Quote:

Originally Posted by Ferrari /img/forum/go_quote.gif It's not a very good idea to use 12V secondary voltage to make 6.3V DC. The heatsink will get unnecessary hot, even without load. Remember that the voltage after the rectifier bridge is ~16V - 17V.

Would it be okay if the power supply outputs 12.6V DC, and feed the tube heaters in series? Is the wiring like this: V+ ---> V+ Tube1 GND ---> V+ Tube2 GND ---> GND

 

[digger945]

Quote:

Originally Posted by ujamerstand /img/forum/go_quote.gif Would it be okay if the power supply outputs 12.6V DC, and feed the tube heaters in series? Is the wiring like this: V+ ---> V+ Tube1 GND ---> V+ Tube2 GND ---> GND

Not sure if I understand your hieroglyphics there, but yes you can use 12v and put two heaters in series. Just connect heater ps 12v to one of the heater connections on board #1, and then run a wire from the other connection on board #1 to one of the connections on board #2, then the other connection on board #2 to heater ps ground. The heater connections on the boards are not polarity sensitive, so you can connect positive or ground to either terminal you like.
Using 12v you'll only need about half the current of a 6v ps.

Embedded Hybrid Headphone Amlifier

 

[ujamerstand]

Ah, why didn't I see that. It makes sense now. Besides that, would it be safe for the tubes and the rest of the amp be power on at the same time? (providing that the headphones are not plugged in, or a muting delay is in effect.)

 

[digger945]

My heater supply is a Radio Shack wallwort. I just plug that in for about 10 seconds and then power up the amp supply(Sigma22), then plug in the phones.
There is a lot of debate about this, and to be honest I don't know the right way to power up things. I would like to do some tests to see what happens in different scenarios, but don't have the time.
I think if nothing is plugged into the phone jack, you should be OK powering up everything at the same time.

 

[johnwmclean]

There’s been quite a few post regarding EHHA set-up, I’d like to run through exactly my plan which may not be the best way but it’s simplistic without the hassle of delays and other components I’m not confident in implementing properly.

My balanced only build is for both speakers and headphones I’m strictly using all recommended components outline on the EHHA site. I will be using three separate enclosures.

The psu will use two σ22’s, Conrad heatsinks, two SumR 120VA transformers housed in a separate customised Par-Metal enclosure together with ε24 and σ24 for a Bulgin power switch, a single 8 pole speakOn connecter will perform umbilical duties.

The heater psu will be housed in a small separate enclosure, using 4 small 1.5A regulators at 6.3V for each board, together with a suitable transformer, I’m also using a single 8 pole speakOn connecter will perform umbilical duties.

Which now leaves the amp enclosure, which will have the two umbilical inlets for the heater psu and the psu for the amp boards, customised heatsinks from Conrad will be used as well as a DACT CT2 attenuator. The enclosure is a modushop slimline 415mm x 350mm x 40mm design, 10mm front panel with thicker style tops and base panels, the tubes will sit up on top of the amp.

So the plan is to basically always turn on the heater psu first, and wait a minute or so before starting up the σ22’s.

 

[dBel84]

Quote:

Originally Posted by ujamerstand /img/forum/go_quote.gif Besides that, would it be safe for the tubes and the rest of the amp be power on at the same time?

"Two power switches are recommended for the EHHA, one for the heaters and one for the +/- 30V rails, because the tubes needs to warm up (for about a minute) before powering up the amp. Otherwise, the EHHA may be prone to misbehavior while the tubes reach their stable operating point."


it is all on the website if you care to read it.

..dB

 

[ujamerstand]

Okay, I thought I've read through that site enough times now. I guess not.

 

[dBel84]

lol, it is perhaps that I know it too well - it is a slow learning experience.

There were people who built it with a single power switch for rails and tubes to come up at the same time. The theoretical problem is that if the tubes do not conduct, the amp can oscillate and go to one of its rails - this would be a bad thing.

..dB

 

[AffeX]

Quote:

Originally Posted by Ferrari /img/forum/go_quote.gif It's not a very good idea to use 12V secondary voltage to make 6.3V DC. The heatsink will get unnecessary hot, even without load. Remember that the voltage after the rectifier bridge is ~16V - 17V.

Thank you for noticing this Ferrari. I also wondered if the 12V would be too much, as you earlier suggested 2x9V.

So from your post I read this:
1. I can run both s22 and heater psu from same torroid without compromising sound quality - otherwise I'm sure you would have said so

2. As 12V AC rectified gives 16-17V DC, then 6V AC rectified might give me 7-8V DC. So why don't I just use the 2x6V secondary as they are?
I was afraid, 2x6V AC wouldn't be enough to give me 2x6,3V DC as I believe the rule of thumb says, AC supply larger than DC needed.

 

[AffeX]

Quote:

Originally Posted by ujamerstand /img/forum/go_quote.gif Would it be okay if the power supply outputs 12.6V DC, and feed the tube heaters in series? Is the wiring like this: V+ ---> V+ Tube1 GND ---> V+ Tube2 GND ---> GND

I believe so. Sinking from your 15VAC to 12,6V DC sounds more right, than my first idea of sinking 12V to 6,3V.
Then you just feed tube heaters in series as explained by digger945. If balanced setup, then in series two by two, and then in parallel.

 

[ujamerstand]

Quote:

Originally Posted by AffeX /img/forum/go_quote.gif I believe so. Sinking from your 15VAC to 12,6V DC sounds more right, than my first idea of sinking 12V to 6,3V. Then you just feed tube heaters in series as explained by digger945. If balanced setup, then in series two by two, and then in parallel.

Yep, I've already got a 50VA transformer with dual secondaries at 15VAC that I can use. I'll use that to power the tube heaters and some more.

On a side note; dBel84 how did you like the HE-5 with your EHHA?

 

[dBel84]

Quote:

Originally Posted by johnwmclean /img/forum/go_quote.gif There’s been quite a few post regarding EHHA set-up, I’d like to run through exactly my plan which may not be the best way but it’s simplistic without the hassle of delays and other components I’m not confident in implementing properly.

Sounds like an excellent layout , looking forward to the completed product.

Quote:

Originally Posted by ujamerstand /img/forum/go_quote.gif On a side note; dBel84 how did you like the HE-5 with sachu's EHHA?

The amp drives the headphones with ease. As for the headphones themselves, they are superb and even better after redamping and tuning to suite my tastes.

..dB

 

[ujamerstand]

Quote:

Originally Posted by dBel84 /img/forum/go_quote.gif The amp drives the headphones with ease. As for the headphones themselves, they are superb and even better after redamping and tuning to suite my tastes.

Nice! Its good to hear that. I've just bought a pair for myself, and I can imagine what an awesome combo it'll be.