[andyr]

It's been a month since I changed the tweeter and midrange crossover board to the ad826. I changed the bass board back to the OPA2134 after only a couple of days. The bass was a little blurred with the AD826.

Just today I changed back to the OPA2134 on the tweeter and midrange boards.  ...

Hi Phillip,

Very interesting, what you noticed but I'm afraid I'm a tad confused by what you wrote ... can you possibly explain?

1.  First up, you say: "The bass was a little blurred with the AD826" ... so I guess you preferred the OPA2134s on the bass?  

2.  But then you say: "Another thing that the ad826 adds is bass since with the Orion, the midrange goes down to 120 Hz".

So you replaced the AD826s on the mid-range part of the ASP board with OPA2134s and you lost bass?  

3.  Then you say: "The OPA2134s are brighter and not as clear on the top end. And there is no midrange with the OPA2134."

So I presume you prefer the AD826s for the upper-bass, the mids & the highs?

But what about the deep bass?  You implied the OPA2134a was crisp (whereas you said the AD826 was blurred) but did it deliver deep bass?

4.  Re. the DC offset voltage in the midrange - I assume it's not there on the treble?

I don't think this offset will be a problem to the AKSAs because of the C1 coupling cap on the input.

Regards,

Andy

[aurelius]

So long as you are using amplifiers that have capacitively couples inputs, there should be no problem whatsoever.

One of the problems with DC offset is that as it accumulates, it can drive the AC center toward one of the rails and cause clipping (think of a +14V DC offset and a 3V p-p output ac waveform).

I have done a fairly thorough analysis of worst-case accumulating DC offset and AD826s in the ASP and, taking into consideration the AC gain of each stage, have convinced myself that there is no problem.  If a couple more stages with DC gain were thrown in, you might end up with problems, but fortunately this is not the case.

I'd leave the AD826s in if they do it for you.

Regards,

M

[PT914]

Hi Andy,

Sorry about the confusion, I tend to explain things in the least amount of words.

The ad826 did not have the impact below 120 that the opa2134 had, but that was with only a few days of listening.  I'll have to listen again.

When I replaced the midrange ASP section ad826 with the opa2134, I noticed a lack of apparent bass so I have to conclude that a lot of "the bass" comes from the 120 and higher region.

So right now I do prefer the ad826 in the mid and tweeter section of the ASP.  The bass section, I'll listen again.

The offset in the tweeter section with the ad826 was in the mV range.

Cheers,
Philip

[PT914]

Thanks M for the offset explanation.  Now I don't have to worry about this offset voltage.  I was reading about putting a diode in the output to the minus line but ...

Anyway thanks,
Philip

[Davey]

"A diode in the output to the minus line?"  Where did you read that?

Davey.

[PT914]

"DVV" use to post in audiocircle and he has or had a web mag zerodistortion.  He talks about opamps and the ad826 with its offset voltage of +.6 volts.  And his cure is a diode from output to minus line.  But since my output was a neg 2v, I didn't know if this would solve my problem.

Philip

[andyr]

Hi Andy,

So right now I do prefer the AD826 in the mid and tweeter section of the ASP. The bass section, I'll listen again. ...

Thanks for confirming, Philip.  Please post again when you've listened!

Regards,

Andy

[PT914]

Hi Andy,

When I re-installed the ad826 into the tweeter, midrange, AND bass ASP, I used a cleaner-enhancer pad to clean all of the opamp pins for the left channel.  This really made a difference, so I had to do the same for the right channel.  Now for the bass evaluation.

I was wrong about the bass for the ad826 or my evaluation was based on dirty pins.  The bass is excellent with the ad826.  Bass is tight and not "fat" like the opa2134 so runs on bass lines can be heard more distinctly.  Kick drums note ends quickly and sound a little different because the bass contribution is timed better with the upper register parts( that is when I had the opa2134 in the bass board and ad826 in the tweeter and midrange board).  There is apparent less bass with the ad826 because of less "fat" notes but more well defined notes, easier to follow.  With the opa2134 "fat" bass notes I thought I was dealing with a little room resonance.

Hope this helps,
Philip

[andyr]

Hi Andy,

When I re-installed the ad826 into the tweeter, midrange, AND bass ASP, I used a cleaner-enhancer pad to clean all of the opamp pins for the left channel.  This really made a difference, so I had to do the same for the right channel.  Now for the bass evaluation.

I was wrong about the bass for the ad826 or my evaluation was based on dirty pins.  The bass is excellent with the ad826.  Bass is tight and not "fat" like the opa2134 so runs on bass lines can be heard more distinctly.  Kick drums n ...

Hi Philip,

Aha, thanks very much for the update.  I can stop stressing now (because I'd used AD826s in my active crossovers for my Maggies!    And I certainly never noticed any lack of bass!).

This "cleaning the pins" trick sound like a really sensible thing to do ... can you tell me what "cleaner-enhancer pad" you used?

Would brushing the pins with Kontac before soldering be the same?

Regards,

Andy

[PT914]

Hi Andy,

If you're soldering, heat and flux will hopefully clean anything.

I'm using IC sockets.  Should have used gold plated sockets.  Anyway, I used something labeled TPC to clean the pins before plugging them in.  Wasn't going to mention the enhancing part but I have to be truthful.  I don't believe or don't want to believe that this part helped and not going to do a comparison.  Cleaning is the main difference.  The opamps comes with a grey coating that I thought was the color of the metal pins, this goes for both the opa2134 and ad826.  You can get the pins to shine by rubbing it with anything.

Cheers,
Philip

[andyr]

Hi Andy,

If you're soldering, heat and flux will hopefully clean anything.

I'm using IC sockets.  Should have used gold plated sockets.  Anyway, I used something labeled TPC to clean the pins before plugging them in.  Wasn't going to mention the enhancing part but I have to be truthful.  I don't believe or don't want to believe that this part helped and not going to do a comparison.  Cleaning is the main difference.  The opamps comes with a grey coating that I thought was the color of the metal pins,  ...

Hi Philip,

As they say in the comics "There ain't no such thing as a free lunch"!!

Yes, using IC sockets makes swapping ICs easy ... but I suspect the extra contact it introduces (at every pin) must not be a good thang, sonic-wise.     So I have always soldered direct to the IC pins.

Interesting what you say about "the grey coating that I thought was the color of the metal pins".  I thought that too ... so I'll clean the pins B4 I do my next op-amp solder job and see what I can get off!     I'm not positive that the heat and flux does actually take off alll the gunk!  

Regards,

Andy

[rick57]

Hi Hugh

Linkwitz states (linkwitzlab.com/orion-faq.htm):
“The crossover/equalizer for the ORION was designed under the assumption that all power amplifiers have the same voltage gain, from input to output.”

For those like me who are considering using different Aksas in the Orion, (my case) the Phoenix (or other active speakers), what are the voltage gains in each of the Aksa amps?

Thanks

[JohnR]

Both versions have the same gain. More info at this link

http://www.aksaonline.com/faqs/faqs_aksa.html#aq10

[PSP]

Andy and Philip,
I remove the gray gunk from all components with emory cloth before soldering.  I keep a piece folded over in half (abrasive sides toward the insides of the fold) on my workbench... it's a simple matter to stick the leads into the sandwich, squeeze down a bit with my fingers and gently pull the part out to clean the leads.  Do this 2-3 times and you are good to go.  Besides cleaning, this puts very fine scratches on the leads, and I think this improves solder wetting and adhesion.

Peter

[andyr]

Hi Andy,

When I re-installed the ad826 into the tweeter, midrange, AND bass ASP, I used a cleaner-enhancer pad to clean all of the opamp pins for the left channel.  This really made a difference, so I had to do the same for the right channel.  Now for the bass evaluation.

I was wrong about the bass for the ad826 or my evaluation was based on dirty pins.  The bass is excellent with the ad826.  Bass is tight and not "fat" like the opa2134 so runs on bass lines can be heard more distinctly.  Kick drums n ...

Hi Philip,

Just something FYI!!  I have recently sourced some AD826s ... they are actually marked "AD826ANZ".  I had to ring AD HQ to find out what the suffix letters mean and was told "the 'AN' denotes the type of packaging anbd the 'Z' means 'lead-free'!!".  

Previous AD826s which I had used (and liked the sound of) were AD826AN ... so I wonder if the new 'lead-free' versions will sound different.  

Unfortunately, it's these new ECC rules against toxic substances which have forced this change of manufacturing materials ... and BTW is also forcing the ancient craft of organ building to die off (as organ pipes often use an alloy containing far more than 1% lead ... the new allowed standard!!)  

Can you advise whether the AD826s you listened to were 'AN' or 'ANZ'??

Regards,

Andy

[PT914]

Hi Andy,

I got the AN version.  Digikey had both for a while and the AN was a dollar less than the ANZ.

Hope this helps,
Philip

[PT914]

I have had the privilege and the challenge of building and testing Hugh’s new  power supply for the Orion active crossover.  Challenging in that HF oscillation kept showing up and with Hugh’s directions I kept changing parts to tame it.  And it was frustrating because at some point it would not reveal itself on an Aksa system driving Paradigm bookshelf speakers that I use in my workshop.  It would only show up on the Orion system setup in the music room.  The HF oscillation was finally solve and this problem actually points out the strengths of Hugh’s PS and the strong point of the Orion system.  Both are capable of great high speed and very high frequency.

  Let me brief you on my crossover.  I have no filter components in the power section except for the LED.  I do have 3.3 uF tantalum caps and .01 Panasonic metal film caps at each ad826.  The PS has no exotic caps just the Nichicon FG caps.

Hugh has a jewel here.  This is the most significant modification I have done to my whole system.  What the other modifications did was clearly point out the fact that something was missing.  This PS adds feeling and emotion back into the music and for the first two weeks of listening I tried analyzing how it did it.  It has fantastic speed, detail, accuracy and high frequency extension but in no way bright.  Violins are sweet sounding and not the steely electronic midi generated sound.  The high frequency harmonics and bow action on the strings replace the steeliness.   The string sections of the orchestra now sound like a chorus of violins, which brings back memories of a live performance.  In fact one can now hear the harmonic or over tones of all the instruments.  This makes it more life like.  The high frequency overtones of the upper octaves on the piano are brought back.  It sounds like a real piano.  There is no tensile anticipation in familiar passages of the high notes from the piano or violin.  It’s relaxing.

A favorite CD for me is Grace II by Paul Schwartz.  A blend of choir, rock, and taste of Celtic.  It demonstrates the speed and the detail of the PS.  On track 9 Ave Maria (not the usual tune) I always heard the soloist singing mainly without any vibrato.  Now I definitely hear a very fast and narrow vibrato.  At times you can hear a little shakiness to the vibrato.  This PS clearly tracks the frequency range of varying vibrato from the wide vibrato of Karen Carpenter and Josh Grogan to the narrowest and fast vibrato like this soloist with the greatest ease.  Detail in that you can hear enunciation of every word and phrasing of lyrics that adds to the emotion of the song.

Speed and detail are also in the bass line where it greatly adds to the rhythm.  I now hear more clearly different techniques used in the upright bass that I didn’t notice before.  Example a pluck followed by a quick hand over the string.

Accuracy to me is reproducing a sound that the brain instantly recognizes.  The best example happened as I was listening to a MHS reissued CD of a CBS masterworks Mozart piano concerto no. 9 and 21 performed by Perahia.  Track 3 is Randeau: Presto for no. 9 and I was concentrating on the pianist when I suddenly heard something not noticed before and instantly recognized what it was.  It was the sound of paper sliding on paper.  The mike had picked up a score change for the pianist at 8:30 into the track.  The amazing part was I knew instantly what it was.  I didn’t have to replay and decipher what it was.

The last couple weeks I stop analyzing and just listened and enjoyed the music.  This PS pulled me back into the classic.  The complex textures of the orchestra and the complex timing of different sections of the orchestra were so beautiful and appealing.  Prior to adding this PS I could not listen to the entire Four Seasons.  The tunes were beautiful but I could not endure the strings screeching.  Now I can listen to it repeatedly and really appreciate the skill and artistry of the synchronized interplay between the violin soloist and the echoing cellist, just beautiful.  I finally realized what this PS was doing.  This PS enhances the power of music to convey the composer’s and performing artist’s intent on your soul.  Be it tugging at your heart or lifting your spirits to a new high, the power of music as a mesmerizing medium is brought out by this PS. You are totally involved in the music.

No matter what I say about this new power supply, I will never do it justice.  Imaging, wide sound stage, it has it all and more.  I honestly believe Hugh has a jewel here.  I want to thank him for the privilege of beta testing this PS during which I learned a lot about oscillation and caps.  And most of all putting joy into my sound system music.

Sincerely,
Philip

[aurelius]

Philip,

This corresponds closely with my experience.  

Sorting the oscillation as a beta tester was indeed frustrating, but the promise that kept revealing itself was undeniable.

To try and describe the change in any audiophile parlance, for me misses the point entirely; its like the difference between watching pictures of the ocean on the TV, versus being able to smell and taste the sea from a beach.  Both you know and identify cereberally as the ocean , but only the latter reaches in to your emotions and evokes memories and feelings of other times and places.  Hugh's power supply does the latter to the music.  There is no perceivable increase in detail, only marginal improvement in tonal balance... but my goodness,  the soul!

Upon re-reading your post, I also concur about not being able to listen to various pieces on the Orions minus Hugh's power supply.  Fatigued is the wrong word... slight disquiet is a better description.  I have a bit of a theory that the closer a reproduction gets to reality, the more ones mind expects the experience of reality, and the more one is critically drawn to notice imperfection... (As an aside, perhaps why I prefer impressionism to realism in art... relaxes my critical mind and by doing so, allows me closer access to the original setting). The orions previously, were so damn close, they were annoying... now they are on the money.

[Dan Kolton]

Hugh,
When do you expect to make this Power Supply available, and at what US cost?

[AKSA]

Hi Philip, Mark,

First, my sincere thanks for being such willing and assiduous beta testers.  Your experience and ability to heft the iron and describe the results has been pivotal.  As you know, I don't have an Orion, Ben (who has a Phoenix) is furiously busy with his new academic job, and nothing beats the real thing.  At least I could drive down to Geelong to spend time with Mark, NoCal is a bit harder!

I have been asked about the Orion before, and always given a very positive review.  I have always felt it to be a masterpiece of Siegfried's meticulous and inspired mind.  I had my reservations however, from past experience unrelated to the Orion, about the crossover, and since forty years of IC development have only marginally improved the sound of these devices, I felt the answer to the unmeasureable quality of good audio, engagement, lay somewhere in the power supply.

Work with the original GK1 design back in 2002 with Darl Singh in NZ taught us both valuable lessons about power supplies.  Over the intervening period I spent long hours in Cafes gazing out the window at the street panorama, high on strong coffee.....  One day it came to me how it might be done.

I spent some time tinkering with the concept and found that it worked, though keeping it stable was an issue which needed solving.  The music tests however showed quickly that this had tantalising potential.....

Dan,

I am hoping to get this into the market, a fully assembled, tested board, for around $US300.  This may vary up or down a little.  The cost reflects four aspects:  performance, modular construction (which is time consuming but protects the IP); a fully assembled and tested product, and utterly unique IP.  There is absolutely nothing else around like this;  the concept is revolutionary.  At the time of order, customers should specify the current and voltage required;  this particular supply is not suitable for power amps;  that will come later.

Again, Philip, Mark, thank you most sincerely for your incredible input!

Cheers,

Hugh