[PT914]

Peter,

I did the sub output change quite awhile ago and I believe it was more articulate in the bass.  But anyone can do the comparison.  Just drive your whole system with the sub output and switch it with the main output of the GK-1.  You just have to disregard the mid and top end.  It's interesting to compare.

Philip

[PT914]

Peter,

For the last 2 hours, been listening to just the bass drivers of the Orion switching between the sub output and main output.  Anyone with an active system can do this and it is very interesting.  Not much music in the 120 to 25 Hz region, just thumbs.  The mid and tweeter adds the attack to the bass line.  The difference I hear between the main and sub out is the weight of the thumbs and the attack of the base line.  I can distinguish between the attack of the kick drum verses the bass guitar more clearly with the subout.  The subout has more weight to the thumbs.  Don't know if the output  attentuation for the sub and main output is the same, but I left the volume the same.  So I think it's worth it but I may be biased, since I went through all this trouble to use the sub outputs.

Hugh,

When you mentioned to Mark about the mid range being 120 degrees out of phase... did you measure this or was it calculated based on the active crossover network?  Would this correct imaging or crossover point summation?

Philip

[andyr]

Peter,

For the last 2 hours, been listening to just the bass drivers of the Orion switching between the sub output and main output.  Anyone with an active system can do this and it is very interesting.  Not much music in the 120 to 25 Hz region, just thumps.  The mid and tweeter adds the attack to the bass line.  The difference I hear between the main and sub out is the weight of the thumps and the attack of the base line. ...

Hi Peter,

Great experiment ... thanks!  In terms of what "music" there is up to 120Hz don't forget, this is the -6dB (half voltage) point of the 24dB/octave, bass LP crossover slope.  So let's say "up to 100Hz" before the signal attenuates noticably.

According to my instrument frequency spread, double base, bass tuba, french horn, contrabassoon, harp, piano and guitar all have appreciable range below 100Hz ... so I'm surprised you didn't hear much, apart from "thumps"!  Were you listening to Dafos "Planet Drum"??  

Regards,

Andy

[eweitzman]

Can someone describe this "subout" feature? I thought it was a feature of the GK-1R but I didn't see anything about it in the product literature.

- Eric

[AKSA]

Hi Phil,

Actually, I don't recall saying 120 degrees out of phase at all, it would have been 120Hz, I'd guess.  Mind you, I don't have total recall (not even Arnie has that, specially after his recent bike spill...) so it could be a senior moment, but I think it's the sub 120Hz band which really appeals with the Orion.  It's just spectacular, and maybe the guy who invented the the non-sequitur 'fast bass' was thinking of an Orion!!

Eric,

The GK1 is an unusual design because there are two preamp sections with a volume control in between, so all input is unattenuated at input and only attenuated at the point where it feeds the input grid of the tube output stage.  This gives the pot a perfect environment and prevents its imperfections lousing up the music.

However, a tube is often said to louse up the bass, so I put in a sub-out at the wiper of the pot.  To a minor extent this loads up the wiper, which is not wonderful, but it means the bass comes through DC to light SS electronics then a pot, rather than passing on through the tube, which for reasons of capacitive coupling diminishes the bass, especially leading edge.  By taking output from the wiper, the level is within spitting distance of the CF tube output, but in fact it's very slightly boosted by the reciprocal of the Av of the CF.

Cheers,

Hugh

[Mark_Walsh]

Hello Chaps,

Where are the Aussie builders of these speakers purchasing their drivers?  Last time I looked, they cost a fortune here, more than double the cost of importing, including customs and freight, from New York!

I would like to support local suppliers if possible, but there comes a point where you cannot.

Regards,
MW

[aurelius]

Hi Mark,

I suspect you've already determined that Accoustic Concepts are the Seas distributor in Aus?

I basically sent them pretty much exactly what you put in your post... "I want to deal with an Aus business, but you need to match the price I could have them delivered to my door in Aus if shipped from the US".

It worked.

BTW, the Peerless drivers are availble for reasonable prices, so don't even consider having them shipped (too heavy).

Cheers

[Mark_Walsh]

Dear Aurelius,

Thank-you for the advice.  I have spoken to the bloke from AcousticConcepts before and "sort of" had that conversation.  The outcome was thwarted by his not having stock and he was going to get back to me on the prices.

Did you get the Peerless drivers from Wesaudio?  They certainly didn't see cheap last time I looked.

All this was about 6 - 8 months ago, so it is certainly trying again.  Can you e-mail me?

Regards,
Mark.

[PT914]

Hi,

Just finished placing Tantalum 3.3 uF caps on everyone of the opamps power pins on the ASP.  Blew one up cuz there're polar and I didn't check my work.  Really stunk the house but luckly its warm in N. CA so I could open all the windows.

This is one of the best things I did to the active crossover.  Total cost was $3.68 and time but well worth it.  This cleans up all the gargage that I didn't know was there mainly in the very high frequency.  I can now hear brushes( maybe individual bush) on the high cymbals.  And there is no burn in time.  I can listen and enjoy it at a lower volume.

Enjoy,
Philip

[PT914]

Here's a confession of a tweaker again.  I've done everything I could think of and what others have suggested and can do no more, maybe.  This is my humble opinion.

With a Aksa GK-1 and Aksa amps driving a Orion system, the weak link or the most beneficial area to tweak is the active crossover.  I'll list the mods from most improvement to least.

1.  Power supply.  As you improve the PS, the background goes silent, except Hugh's PS.  His PS caused all others to be dull and lifeless and this is not even the "creme de la creme."  My crossover board has nothing in the DC supply section except for the LED1.  Cost is less than $80.  Most of that is the trans and filter caps.
2a.  Tantalum 3.3 uF caps in addition to the .01 uF that are on the board.  I have to correct my last post, it cost 50 cents apiece for the tantalum so about $25.  This cleaned up the hash you don't realize is there.
2b.  B because you have to do A first.  Opamp change to ad826.  This is a dollar more than the opa2134.  I was at first concerned about the dc offset, but didn't notice a thing.  This mod is almost like the PS.  It adds life and sparkle to the music but you may need a sweet top end(teflon).
Now when I play a CD, it's like inviting someone to perform in my room, it's  scary.
3.  MultiCap RTX at C204,205,206, and 207.  Beautiful midrange.  I can follow notes and chord structure of the left hand on piano parts.  I can follow the alto parts on chorus parts.  The RTX also opens up the stage in 3D.
4.  VH teflon caps at C35, 36, 49, and 48.  Sweet top end.  A pain to burn in and expensive, luckily they are .033 uF and not higher.
I didn't list doubling up the boards, one for the tweeter and midrange and one for the bass because if you have a GK-1 this is a must to take advantage of Hugh's cleverness.  That's it.... well until Hugh's new and better PS.

Good listening,
Philip

[andyr]

Hi,

Just finished placing Tantalum 3.3 uF caps on everyone of the opamps power pins on the ASP.  Blew one up cuz there're polar and I didn't check my work.  Really stunk the house but luckly its warm in N. CA so I could open all the windows.

This is one of the best things I did to the active crossover.  Total cost was $3.68 and time but well worth it.  This cleans up all the gargage that I didn't know was there mainly in the very high frequency.  I can now hear brushes( maybe individual bush) on the h ...

Hi Philip,

WRT your next post - using AD826 opamps instead the OPA2134 - are the Tantalum 3.3uF caps needed for this op-amp as well?

BTW, I use AD826s in my active crossovers.  I used them on DVV's advice (who posts on this Forum from time to time).  I also use Hugh's E-F PS in these!

Regards,

Andy

[AKSA]

Hi Philip,

Thank you for publishing your findings.  I noted a long time ago that there were sonic improvements to be had from Seigfried's brilliant design in the crossover;  his use of standard regulators was not my choice, as I'd tried them on the GK1 and found them lacking.

I have consolidated the new design after long hours in cafes with strong coffee and a couple of days ago did some careful experiments on the new design.  It is coming along well, and the pcb design is now well in progress.

The first design will be a universal bipolar supply suitable for up to +/-24V at up to 400mA.  You'll be able to tailor it to need;  for example the Orion crossovers need +/-15V @ 300mA.  Ultimately, I will do one for the amps as well.  These will be aftermarket products, offered for those who want the very best sonically for their systems.  No idea yet on cost, but will let everyone know through the website.

Cheers,

Hugh

[aurelius]

Thanks for posting Philip,

I have read others posting that AD826 swap-outs made no difference... I suspect the power supply was their limiting factor.  As previously posted, I noticed significant gains by upgrading my PS. SL's PS sounded sluggish by comparison.

Have you tried an ALW super regulator and if so, do you find Hugh's power supply better?  Is it just the GK1 regulator design or something new and wiz-bang?

I think I will try AD826's all round, bypassed by 0.1uF BG NX soldered directly to the chip PS pins.

Thanks again for reporting your findings.

Mark

[PT914]

Hi Mark and Andy,

My progression of power supply was; stock to Hagerman to alw with decreasing quietness.

The digikey data sheet on ad826 shows bypassing with 3.3 uf caps.

There was actually distortion with the opa2134.  I have Josh Groban CD and always thought the cd was defective.  I could hear distortion on his vibrato(his vibrato is very wide range and goes very high) especially on track 11 "home to stay."  Now it's gone.

Good listening,
Philip

[Dr. Krull]

I would suggest evaluating the sonic merits of the AD826 compared to the OPA2134 by listening to each of them in a prototype test rig prior to replacing a 22 chips in your crossover.  On a protoboard setup a unity-gain circuit with an opamp socket.  Listen to each chip with this test rig between your preamp and power amp.

Based on my own testing I find the OPA2134 to be the better sounding device.  You might also want to listen to the AD8620, which IMO is far better sounding, albeit very expensive.  System synergy obviously plays a role in which chip you ultimately prefer, so YMMV.  As I understand, SL was very pragmatic about what devices he uses in his circuits, and therefore, don't assume that he selected the BB chip by accident, or that he was blind to alternatives.

-Krull

[PT914]

Hi,

Just want to say again that these were my humble opinion for my system and my ears.  Everything is a compromise.  My goal is to have someone almost life like singing in my room.  The high end can be a problem with the ad826 if you don't have sweetness and Aksa.  Maybe the base is a little blurred but the GK-1 solves that.  The easiest method for me to evaluate the changes was to do one side at a time.  You can't evaluate imaging very well but tone was very noticeable.  I'll also listen for a month and maybe change back to the opa2134 and see if I'm missing anything.  Opamp change is very easy.

Philip

[PT914]

Since I have two boards, I can change the base board back to the opa2134 to get the base attack again. I hope you can mix opamp without phase problems.   Here we go again tweaking.

Philip

[SamL]

Hi Philip,

The first design will be a universal bipolar supply suitable for up to +/-24V at up to 400mA. You'll be able to tailor it to need; for example the Orion crossovers need +/-15V @ 300mA. Ultimately, I will do one for the amps as well. These will be aftermarket products, offered for those who want the very best sonically for their systems. No idea yet on cost, but will let everyone know through the website.

Hi Hugh,

Will this (to be release) power supply handle multiple +/-15V active crossover board?
It is possible to toiler the ouput to say 27VDC? It is for headphone amp that I yet to build.

Thanks,
Sam

[Builder Brad]

Hi Phillip,

I have upgraded both the L+R active x-over PS on my orions using the super reg JSR06 as per the P-A projects shown here.

http://home.swipnet.se/~w-50719/forsale/index.html

the improvments were significant compered to the ELPAC switching unit recomended by SL

I am currently building another active x-over using a spare set of ASP boards. My current x-over is built around the earlier Phoenix boards and takes up more room than the newer Orion ASP esp. combined with the Thor x-overs and active circuitry,

I will probably use the old x-over for a pair of Orions in another part of the house.......Hugh has promised to send me an updated chip for my GK 1R to allow me to by-pass the output on one input only(squeezebox), which should stop me from using the sub out on the Gk 1r and separate bass and hf x-overs.

I intend spend more time matching the x-over cap and resistor values to get as near to perfect x-over points and am considering the additional 3.3uf Tant caps for each OP amp supply. I will not look at different OP amps at this stage but want to know if you heard an improvent with the 3.3uf caps on the OP2134s? given the oportunity of a blank ASP pcb are there any other mods that I should consider before starting to solder those components?

what value RTX caps are you using?

[AKSA]

SamL,

I'm doing two power supplies;  one for preamp duties up to +/-24V @ 400mA, and a second which will be designed for the AKSA 55.  If the latter is successful, I will build it out for the 100W amp as well.  From various emails from tweaking customers I fully expect supply regulation to sound very different.  Whether it will be better is moot, but I suspect most will judge it to be superior from a resolution and noise point of view.

Design, bench testing and pcb layout is done for the preamp supply and prototype pcbs are being made right now.  I fully expect this to be the best power supply available for DIY yet, but heck, I might be wrong, so we will be extensively beta testing it both here and in the US.  It uses unique circuitry, Malcolm Omar Hawksford's feedforward concepts, to avoid the usual pitfalls of negative feedback and ringing which beset many supplies, even the more complicated ones.  The error correction is current driven from the front end, extremely fast, and the transfer function can be tweaked to even give a negative output impedance with perfect stability.  

So, Sam, either of the power amp supplies should thus be suitable to your higher voltage requirements.

Brad (and other GK1-R owners!!),

Ben handed me several updated chips recently so I'm ready to hand 'em out.   The update adds the following two functions:

#1  On switch-on, starts with mute, defaults to the source of your choosing at previous switch-off (selected by simply holding the appropriate button down for two seconds), then removes mute after about four seconds.

#2  Permits HT Bypass to be selected ONLY from AUX.  If the source selection is not AUX, then HT Bypass does not activate.  This should save a few speaker cones!!


Guys, if you would like one, email me and I'll get 'em out.  They will be $US15 each including postage anywhere in the world.  If there is a flurry of orders, it may take a few days.

Cheers,

Hugh