[Sathimas]

Guys ... I'm damn excited ...

Just begun testing my exstata - power supply runs !!

Next step is bias setting, then I'll test the amplifiers.

Just writing here to calm down and lower my pulse

The only bad thing is that even when everything works and the amp comes alive properly I won't be able to enjoy the sound.
I visited a much too loud concert yesterday evening and my ears are still a little numb and the left one gives me a constant *peeeeeeeeeep*.
It already got better and will disappear completely I think but it really gets to me at the moment ...

 

[cosmopragma]

Quote:

Originally Posted by Sathimas /img/forum/go_quote.gif I visited a much too loud concert yesterday evening and my ears are still a little numb and the left one gives me a constant *peeeeeeeeeep*. It already got better and will disappear completely I think but it really gets to me at the moment ...

No, this will never disappear completely.
Symptoms a day later means permanent damage, that's for sure.
Let's hope the end result will not be a permanent tinnitus but only a minor hearing loss.
In any case, investing in high end gear and attending loud shows like the average knowledgeless bum without being protected by hearing protection (e.g. Etymotics ER-20 or similar) doesn't mix well.
Be careful .......

 

[Keithpgdrb]

Quote:

Originally Posted by Sathimas /img/forum/go_quote.gif Guys ... I'm damn excited ... Just begun testing my exstata - power supply runs !! Next step is bias setting, then I'll test the amplifiers. Just writing here to calm down and lower my pulse The only bad thing is that even when everything works and the amp comes alive properly I won't be able to enjoy the sound. I visited a much too loud concert yesterday evening and my ears are still a little numb and the left one gives me a constant *peeeeeeeeeep*. It already got better and will disappear completely I think but it really gets to me at the moment ...

I remember thinking that it would go away. that was a long time ago. Invest in some good ear protection now, and always have those foam earplugs stuffed in every pocket of every jacket. availability is the key. I've even resorted to stuffing TP in my ears at a show. was worth it. Anyway, back to the ExStatA!!!

 

[Sathimas]

Well ... a good hearing protection is something I wanted to buy since the beginning of that year and will definitely buy this week.

About disappearing or not:
I am studying medicine and have just made an internship at a doctor who treats tinitus/hearing loss and so on.
The chances for those things to disappear are'nt that low at all.

I already had that once very bad - hearing loss (heights) and tinitus on both ears for 3 or 4 days after my first big concert at all (AC/DC).
Disappeared afterwards.
I also experienced something like this when working in very loud places but it always went away.

The last years I always use hearing protection in loud places, even if it is only for seconds.
But yesterday I just had nothing there...

Just be optimistic with me!

For the exstata:

It just burned one of the two fuses as I switched him off, seems that they are to "small".
All the rest seems to work good.

 

[Beefy]

Quote:

Originally Posted by Sathimas /img/forum/go_quote.gif Well ... a good hearing protection is something I wanted to buy since the beginning of that year and will definitely buy this week.

Every music lover should have a set of these.

 

[Sathimas]

Ok - problems:

I can not get the offset stable on one channel, the other one seems to work just fine.

When I remember correctly that problem can occur if the jfets are not "good" enough and my quad was like 9.86, 10.14, 10.5, 10.8 ...

Could that be my problem?

 

[les_garten]

Quote:

Originally Posted by Beefy /img/forum/go_quote.gif Every music lover should have a set of these.

Thanx for that link!

Motorcycles and open pipe Porsche's have had a few go rounds with my Hair Cells, so I try to be a little more responsible now.

 

[Sathimas]

Some measurements:

Power supply:

- T1-T2: 360mV
- T3-T4: 410mV
- Rails are 317 and 312V
- T1/T3 against ground are ~330V

Transformer output voltage is 252V, I am using a 300V zener string.

Amp Boards:

Left channel:
- Across out +/ out - drifts very little arround 50 to 60mV
- out - to ground: drifts around ~500mV, down to 100mV and up to 700mV
- out + to ground: arround 180mV, relatively stable

right channel:
- across out + / out - drifts arround 10mV
- out - to ground and out + to ground is the strange thing:
I can only get one output close to 0VDC, the other one (either plus or minus) is arround 20V then
But its not possible to get those values stable

I also checked the power consumption of the whole amp - initial is about 50watts,
after about 5 minutes it stabilizes at about 46watts. (I just remember asking someone about that some pages ago...)

 

[runeight]

The amp will naturally drift. Even 1 or 2V is ok although most of the amps do much better than this. Hundreds of mV drift is actually very good for an amp than has no control circuitry for this. So no sweat on this item.

However, are you also not able to adjust either the offset or balance to 0 on one of the channels? If this is so then it probably is a jfet matching issue.

 

[Sathimas]

Just to clarify:

right channel:
- across out + / out - drifts arround 10mV (absolutely ok then)

- out - to ground and out + to ground is the strange thing:
I can only get one output close to 0VDC, the other one (either plus or minus) is arround 20V then
But its not possible to get those values stable

So if attach the probes to out+ and ground and adjust the voltage close to 0VDC and then attach the probes to out- and ground the reading will be at least 20V.
When I then adjust out- to ground close to 0VDC out+ will rise up again.

It is the board with the one jfet that only had a 9,86mA reading ...

(The other board shows no problems, offset and balance are ok.)



I just knew it, my DIY-career seems star-crossed

But those glowing tubes are worth it, really really worth it.
I also built a SOHA I and a SOHA II yet (which worked immediately!) and liked them very much but the exstata is my first amp with
tubes that do not have to lighted with LEDs to shine ^^

Thanks for giving this amp to the community and your great support !

 

[Beefy]

Quote:

Originally Posted by Sathimas /img/forum/go_quote.gif Just to clarify: right channel: - across out + / out - drifts arround 10mV (absolutely ok then)

...... only drifting 10mV? I find that very hard to believe. Are you sure that you are measuring correctly?

 

[Sathimas]

it is drifting around the center of 10mV - not +/- 10mV

But my DMM isn't the best anyway - when I have new jfets I will ask a friend to bring a professional one from his work.

 

[paxeaxe23]

FINALLY!

Its all done. I'm sitting here listening to Simon and Garfunkel, E.L.P., Chicago Symphony with Reiner (R. Strauss) as well as some home recorded Horn quartets and a few recordings of my Orchestra to hear myself. Moody Blues, and Michael Buble. just to name a few. No doubt I'll be sitting here in a week still listening.

This is really an excellent Amplifier, very transparent, very clear High's and a surprisingly tight and definable bass line too. The mids are also very balanced and acoustics of the recordings come through as if I were there myself.

I am listening on my SR5's and will now probably have to go out and get a pair of 404's so this isn't really a budget build

Thanks to everyone who helped me through this my first BIG (and definitely NOT my last either, I'm hooked!) project, I'll post a more thoughtful piece on the first impressions thread once I have made a final judgement, but wanted to let you all know I got there and say thanks to you all, but especially to Alex. This design is a great contribution Alex, thank you from the bottom of my heart.

Francis

 

[pabbi1]

I made a 1970's run over the weekend through E.L.P., Golden Earring, 10 Years After, Alice Cooper, Uriah Heep, Joe Cocker, and a couple of compilations - this amp really shows what we missed all those years on the radio, and the quality and care of the recording industry at the time.

It continually amazes me the number of things I can now listen to and really LIKE, that had been completely run over with terrestrial radio - like 'Freebird', 'Highway Star', 'Stairway', and all number of obscurities. It really is fun to run through a compilation, especially full of junk I'd never put on as a seperate selection, and see what pops out.

The genius of this amp is that it makes stats FUN, in addition to being fast, detailed, precise and balanced. That is a very unusual convergence.

 

[BoilermakerFan]

Quote:

Originally Posted by pabbi1 /img/forum/go_quote.gif I made a 1970's run over the weekend through E.L.P., Golden Earring, 10 Years After, Alice Cooper, Uriah Heep, Joe Cocker, and a couple of compilations - this amp really shows what we missed all those years on the radio, and the quality and care of the recording industry at the time. It continually amazes me the number of things I can now listen to and really LIKE, that had been completely run over with terrestrial radio - like 'Freebird', 'Highway Star', 'Stairway', and all number of obscurities. It really is fun to run through a compilation, especially full of junk I'd never put on as a seperate selection, and see what pops out. The genius of this amp is that it makes stats FUN, in addition to being fast, detailed, precise and balanced. That is a very unusual convergence.

And you're not even listening to it properly, which is of course, on vinyl as that was the preferred medium in the '70s. Just imagine how good it would sound on vinyl via a Grado Gold or Denon DL103 cartridge on a modded RB250 tone arm in a modded Planar 3 TT through an AudioSector, TubeCAD Tetra, or Pass DIY Pearl2 phono stage.

EDIT: I'll let you know after I get all three of those phono stages built, then purchase and mod the TT.

Figure I need to test a great Op-Amp, tube, and discrete SS phono stage, so I'll have to build all three.