[runeight]

The way I see it is that you will connect the O/P of the amp to the two outside leads of the capacitor pair. Then take the signal from across the 4700p cap using two 1X probes and the scope in differential mode for its two inputs. Since the probe capacitance is generally small and will be in parallel with the 4700p cap its effect should be negligible and calculable.

 

[runeight]

But, now that I think more this won't solve the standoff problem.

 

[runeight]

You know, we are making this harder than it really is because this is a differential amp.

The rails on this amp are +/-300V. Neither ouput can go past its rails so if you connect two probes from the scope in differential mode neither probe will see more than 300V with respect to ground. There could be 600V between the probes but then there is twice the insulation between them.

 

[sumo-kun]

So I got home from work just now and the boards arrived! Yippee! They look as stunning as everyone says

Now I just got to scrounge together the parts and put it together

Just a quick question. Regarding transformers, I will probably need to get a custom one made since there seem to be no off the shelf and reasonably priced ones around here. I looked around and I found that an EI trans will cost only a little less than an R-core and an EI orient core is about the same or a tiny bit more. Also there are R-core toroids available. Not sure how much they are though. They're made by the same company that invented R-core transformers. So with the minimal price difference between all these types, which would be the "best" one? My case will be as compact as I can manage so I'm leaning towards R-cores right now... Any suggestions?

 

[Beefy]

sumo-kun - are you doing the hybrid or solid state? I got a custom toroid for my solid state build and it works a treat.

 

[paxeaxe23]

Hi! I am considering building from this design, sounds really good. However I am not clear as to which STAX I could use with this. I own a pair of SR-5's and these are the so called normal bias which as far as I can see are 230v . Is it possible to adjust the Amplifier to work with these Headphones?

 

[scompton]

There can be outputs for both normal and pro biases

 

[paxeaxe23]

Yes, I have been spending the last hour reading the whole thread and managed to work that out. Nice to have something like that confirmed though, its a lot of voltage to be playing with!

Thankyou

 

[BoilermakerFan]

Quote:

Originally Posted by sumo-kun /img/forum/go_quote.gif So I got home from work just now and the boards arrived! Yippee! They look as stunning as everyone says Now I just got to scrounge together the parts and put it together Just a quick question. Regarding transformers, I will probably need to get a custom one made since there seem to be no off the shelf and reasonably priced ones around here. I looked around and I found that an EI trans will cost only a little less than an R-core and an EI orient core is about the same or a tiny bit more. Also there are R-core toroids available. Not sure how much they are though. They're made by the same company that invented R-core transformers. So with the minimal price difference between all these types, which would be the "best" one? My case will be as compact as I can manage so I'm leaning towards R-cores right now... Any suggestions?

As it was explained to me by a custom E-I transformer manufacture, the R-Cores are unique transformers in respect that they have a compact, flat profile like a toroid, but the they have the better noise rejection properties of a E-I type core. If they were not so expensive to ship here from HK, I would have used R-cores in my builds.

I have custom E-Is from a US company for my eXStatas and I'm ordering custom shielded and potted toroids for another 3 projects from the same vendor Beefy ordered his from.

 

[macm75]

I'm sure it was discussed or thought of during the design of the hybrid pcb, but just in case, for next project consider designing so the tubes mount on the opposite side of the pcb. Shame to see tubes inside boxes. BUT I do realize I can mount the tubes on "chassis" sockets, mount the pcb's upside down to the top plate, and solder wire from sockets to pcb.
Top plate with power transformer centered on back side and a line of 6S4A's in the front would be nice presentation. Think about it Hybriders.

 

[pabbi1]

Boring, Sydney... boring.

This was prototyped, but could not get to the biasing pots. The boards are small to minimize the signal path, but this is how I am going on a new experimental build. Let's just say I have a burning desire.

 

[luvdunhill]

Quote:

Originally Posted by runeight /img/forum/go_quote.gif You know, we are making this harder than it really is because this is a differential amp

...

 

[macm75]

Would you use this resistor? It's R1, 1M, on the amp board. It still reads 1M.
Maybe just put some heat shrink around it?

 

[macm75]

Quote:

Originally Posted by pabbi1 /img/forum/go_quote.gif new experimental build

Nice - top plate above the socket plate - no screws visible

 

[les_garten]

Quote:

Originally Posted by macm75 /img/forum/go_quote.gif Would you use this resistor? It's R1, 1M, on the amp board. It still reads 1M. Maybe just put some heat shrink around it?

I hate trick questions like this...