[jdkJake]

That looks great Bloodinside! Excellent use of available space!

The binders are an interesting idea for cable management.

 

[BoilermakerFan]

Quote:

That looks great Bloodinside! Excellent use of available space!

The binders are an interesting idea for cable management.

I agree!  That has given me the idea to acquire some SS or copper tubing and use an abrasive blade to kerf out about 2/3 of one half so it would look similar to the binder, but be solid metal.  Soft copper tubing could be bent to shape first too.  
 
 

 

[BloodInside]

Quote:

Nicely done. Did you make the chassis yourself?

Thanks. I bought the chassis/case from a Dutch company called Automatic Electronics Europe. They have a Dutch website and they are in the progress of building a new webshop which is also available in English.
 
Quote:

That looks great Bloodinside! Excellent use of available space!

The binders are an interesting idea for cable management.

Thanks. I picked up that idea from the modeltrain hobby scene. It is cheap (paid about 8 euro's for a 100 A4 binders) and works really well.

 

[Alcaudon]

Thanks BoilermakerFan and holland for the advices, and explanations.
 
The idea was to drive a pair of k1000 with a balanced ehha, but maybe the ehha is not a good chice for a first balanced amp, too many complications. I think I'm staying with a standard build and save money/effort for a balanced Bijou in the future

 
Quote:

 
Quote:

 
Quote:

No, I meant to take a page from the playbook of a master:http://www.head-fi.org/forum/thread/85561/post-pics-of-your-builds/3225#post_4153931(see Ferrari's kumisa III build on this page)

Oh! now I see what you mean

 
Yes, this could be a solution, I'll definitely have to check that, thanks jdJake

 
Still wondering if someone has any experience with a balanced EHHA Rev. A....

Balancing the EHHA would result in twice the gain and that is probably way too much unless you have a very low output source or you really increase the NFB and drop the CL gain.  I don't think I would want to make those two changes since they will have large effects on the SQ.  The EHHA could be modded and biased to output more power with bigger heatsinks even in SE, so I don't see the need for the balanced amp with headphones.  I was considering a balanced or bridged build for speakers, but now I think just paralleling output FETs and mounting them off board makes more sense; however, even this will require tweaks to the PS and several resistors need to be changed too so I'm reconsidering even those changes. 

 
Quote:

OL and NFB are tied together in that the OL gain defines how much NFB is used to achieve the CL gain.  The CL gain, being somewhat fixed.  Think opamp.

 

 

[jdkJake]

The idea was to drive a pair of k1000 with a balanced ehha, but maybe the ehha is not a good chice for a first balanced amp, too many complications. I think I'm staying with a standard build and save money/effort for a balanced Bijou in the future

 


If gain is your concern with a balanced EHHA, you could always run 2.4k at R11 and somewhere around 33k at R13 and R14 and come in around a gain of ~10. This is just slightly above the default single-ended gain of ~9 with very close to the same amount of NFB (~34db).

That being said, I was always under the impression the k1000's appreciate a bit of extra gain, so, perhaps it is a non-issue with those specific phones. I do not own a pair, so, I cannot comment on their performance.

Just a thought before you dismiss the idea entirely.

 

[holland]

Quote:

 
If gain is your concern with a balanced EHHA, you could always run 2.4k at R11 and somewhere around 33k at R13 and R14 and come in around a gain of ~10. This is just slightly above the default single-ended gain of ~9 with very close to the same amount of NFB (~34db).That being said, I was always under the impression the k1000's appreciate a bit of extra gain, so, perhaps it is a non-issue with those specific phones. I do not own a pair, so, I cannot comment on their performance.Just a thought before you dismiss the idea entirely.

Agreed.  It's also no more complicated than any other amp or fast bipolar opamps to begin with, which I why I keep bringing up the opamp reference.  The EHHA I was unity gain stable, you just need compensation caps.  Mine is built with a gain of 4, and a 15pF compensation cap, below a gain of 8, to eliminate ringing on a 100KHz square wave.  It slows the amp down, but no biggie, to me anyway.  I don't know if the EHHA A needs it.  You'd need a simulation or a scope measurement to be sure.
 
Even the B22 needs a change of compensation caps for different gains.

 

[BoilermakerFan]

How much power do the K1Ks really need?  You could probably push 4W per channel out of a SE EHHA RevA with 2-1/2" heat sinks if you bump a few resistors up to 1/2w and 1w values and tweak the PS caps a little.  The trafo would need to be bumped up and it will be burning off more voltage at the V-regs if the load isn't there so they need to be on 2-1/2" sinks too.  But a balanced EHHA will be easier to setup and dial in than a balanced Bijou. 

 

[keyid]

Quote:

I agree!  That has given me the idea to acquire some SS or copper tubing and use an abrasive blade to kerf out about 2/3 of one half so it would look similar to the binder, but be solid metal.  Soft copper tubing could be bent to shape first too.  
 
 

im planning on doing this, tried this on another build and removed hum from over exposed wire.

 

[stringgz301]

Question: if one were going to build a balanced version of the Rev A amp,  what spec would you use for a SumR transformer?

 

[jdkJake]

Question: if one were going to build a balanced version of the Rev A amp,  what spec would you use for a SumR transformer?

 


Same voltage, double the current. Or just use two of them.

Depending upon your AC line in, you might want to go a bit lower on the 30-0-30 secondaries. What does your AC normally measure? Closer to 115VAC or 120VAC?

 

[stringgz301]

Actually a touch above 120v AC (120.3).

 

[gurubhai]

Quote:

How much power do the K1Ks really need?  You could probably push 4W per channel out of a SE EHHA RevA with 2-1/2" heat sinks if you bump a few resistors up to 1/2w and 1w values and tweak the PS caps a little.  The trafo would need to be bumped up and it will be burning off more voltage at the V-regs if the load isn't there so they need to be on 2-1/2" sinks too.  But a balanced EHHA will be easier to setup and dial in than a balanced Bijou. 

How does one calculate how much power EHHA outputs?
Can someone point me towards the calculations required.
 

 

[jdkJake]

Actually a touch above 120v AC (120.3).

Based on a quick look, I think the main discussion on the topic was around post 830 or so. Might want to go back and peruse a bit. You have the possibility of going a bit lower if you want.

At that line voltage, the sumR seems to be coming in around ~38VAC at the regulators. A bit higher than the 35-36VAC Alex recommends. However, it does give you a bit more headroom for additional load components (like an e12) and a higher MOSFET bias. Also generates a bit more heat.

Were you not getting about ~39VAC with your Avel? Should be comparable or less than that. How are you getting along with that part?

 

[holland]

Quote:

How does one calculate how much power EHHA outputs?
Can someone point me towards the calculations required.
 

I don't know if it's been measured, to be honest.  The voltage swing should be about 43Vpp to 45Vpp, about 16Vrms, unloaded.  Current output in class A should be about 200mA.  This does not mean that you will achieve this into an arbitrary load.  Into a 32-ohm load, the voltage swing will be limited, as it will likely clip around 35Vpp to 40Vpp.
 
The best way is to measure, but it will be a significant amount of power.  If you bias to 160mA, it will be at the B22 level of power output.  With the default 100mA, it will be less of course.
 
Are you looking for something in particular?

 

[gurubhai]

^A friend of mine asked if EHHA could power HE-6. According to my calculations HE-6 needs about 1.5Watts at 50 ohm to push it to SPL of 115dB. I suppose even a standard EHHA build should be able to manage that but wasn't sure. So, I thought I should better ask.
Amb's site has B22's measured power output as 5.4W at 32 ohms BTW.