[Freo-1]

My buddy built this for me recently. It uses the Aikido circuitry, and it is all point to point, with high quality parts used. The power transformer is a NOS Freed, and the choke is NOS.

http://www.audiocircle.com/index.php?action=gallery;area=browse;album=1421&pos=5/

So far, I've used 6DJ8/6922, and 6CG7 input tubes, with 5687 drivers. The 5687's I've tried are GB 5687 and Tung Sol 50's D getters.

I've tried various 6922/6DJ8 types, and my favorite is the Siemens 6922 from the late 60's followd closely by Valvo 6922 from the early 60's (Phillips).

The 6CG7 sounds incredibly lush in this preamp. My favorite so far is the early RCA with shield, side D getter, and flashing on top and the side. The flat black RCA from the 50's is also very nice, as is the shiny black plate type from Raytheon.

So, who's made one of these, and what are your impressions? My unit replaced an ARC SP-11, and this unit is a big step up in clarity , dynamics, and performance.

It may be some time before I ever buy a commercial preamp again!

[Kevin Haskins]

My buddy built this for me recently. It uses the Aikido circuitry, and it is all point to point, with high quality parts used. The power transformer is a NOS Freed, and the choke is NOS.

[img]http://www.audiocircle.com/image.php?id=16304/img]


So far, I've used 6DJ8/6922, and 6CG7 input tubes, with 5687 drivers. The 5687's I've tried are GB 5687 and Tung Sol 50's D getters.

I've tried various 6922/6DJ8 types, and my favorite is the Siemens 6922 from the late 60's followd closely by Valvo 6922 from the early 60's (Phillips).

The 6CG7 sounds incredibly lush in this preamp. My favorite so far is the early RCA with shield, side D getter, and flashing on top and the side. The flat black RCA from the 50's is also very nice, as is the shiny black plate type from Raytheon.

So, who's made one of these, and what are your impressions? My unit replaced an ARC SP-11, and this unit is a big step up in clarity , dynamics, and performance.

It may be some time before I ever buy a commercial preamp again!

I have one but it isn't built yet.   It should be a good design and there is a lot of flexibility in tube choices.    Glad to hear your getting good results.   It will motivate me to build a power supply and get mine finished. 

[Freo-1]

Thanks, Kevin!  It really sounds great.

PS: I fixed the link  to the pic.

[santacore]

That thing looks awesome. Great to hear that it sounds as good as it looks.

[BillB]

Nice, I like the brown transformers!!

I have a 5687/6cg7 Aikido but it is not complete but I am using a 24v Aikido in my system right now...I love it.

I have some GE and Phlips 5687 and RCA Cleartop and EH 6cg7.

I want to get some bronze plate 5687 Raytheons. I need to get to work on that board!!

[Freo-1]

Nice, I like the brown transformers!!

I have a 5687/6cg7 Aikido but it is not complete but I am using a 24v Aikido in my system right now...I love it.

I have some GE and Phlips 5687 and RCA Cleartop and EH 6cg7.

I want to get some bronze plate 5687 Raytheons. I need to get to work on that board!!

I would recommend point to point construction. Makes it easier work on, and most folks reckon point to point is better sonically.

[BillB]

Well, I already have the board populated...

I just finished my first p-p project today...I suppose that with some serious layout fore-thought you could have shorter runs but I damn sure didnt!!  Not sure about sound, haven't been able to compare the difference. One thing I do like about P-P is you are not space limited for components, but the Aikido boards are built with a lot of flexibility, my 24v has a 4uf motor run film cap (about the size of a zippo) on the headphone side and it fit with plenty of room to spare.

[JoshK]

Mine is nearing completion...just some final wiring to do.  The SET amp is first and its almost done.  My is all octal, set up for all 6SN7's first, but I have some octal 6H30pi's to try for driver too.  I reckon the gain makes the sound so long as the driver is adequate. 

You didn't mention how you like the sound.  What did you compare it with?

[Freo-1]

Well, I already have the board populated...

I just finished my first p-p project today...I suppose that with some serious layout fore-thought you could have shorter runs but I damn sure didnt!!  Not sure about sound, haven't been able to compare the difference. One thing I do like about P-P is you are not space limited for components, but the Aikido boards are built with a lot of flexibility, my 24v has a 4uf motor run film cap (about the size of a zippo) on the headphone side and it fit with plenty of room to spare.

No worries. I'm sure it will be fine.

 I would highly recommend to get a pair of Tung Sol 5687's. They really are in a class by themselves sonically.

Let us know how it sounds once it's done! (I'm sure you will be most pleased).

[Freo-1]

Mine is nearing completion...just some final wiring to do.  The SET amp is first and its almost done.  My is all octal, set up for all 6SN7's first, but I have some octal 6H30pi's to try for driver too.  I reckon the gain makes the sound so long as the driver is adequate. 

You didn't mention how you like the sound.  What did you compare it with?

I love the sound!

I've had an ARC SP-6E, SP-11, McIntosh MX-110, Citation IV, Dyna PAS-3X, PAS-4, Melos SHA Gold, and this beats all of them by a lot!

I love the fact that one can change out a variety of preamp tubes to go for a different sound. The 6CG7 is very lush sounding, while the 6922's bring out loads of detail.

I want to try 6AQ8's next.

It's also quick sounding and quiet. With Sylvaina GB 5687, it's DEAD quiet.

BTW, my buddy also has an octal preamp he made for himself, but after this project was completed, he liked the sound of this unit so much, he is currently making one for himself, and may sell his octal (he makes amps and sells them locally to make a little extra cash).  He was quite taken with the sound using 6DJ8/5687 combo.

[Freo-1]

The amp I'm using is a modified Citation II.  The front end driver tubes were replaced with 5687 triodes from the stock 12BY7 pentodes, along with a upgraded bias circuit that is rock solid. The amp is biased to 60 ma, and sounds great.

Although I love the Citation II stock, this revision sounds more open, quick, and dynamic. It has a natural presentation of the soundstage that makes one think "you are there" with SACD/DVD Audio sources.

I've caught some flak from Citation II owners who think changing out the front end is sacrilege, but it does make the presentation less "hi-fi" sounding.  The topology is very similar to the MFA monoblock amps.

http://www.audiocircle.com/gallery/albums/userpics/53818/SP12_008%7E0.jpg

[JoshK]

Well regarding the deuce, it was an engineering marvel of its day.  I am not qualified to critique all the choices but there was a lot of tweaking to get very wideband performance and stable behaviour open loop so that feedback could be used without penalty.  Lots of cool local feedback loops. Many say local feedback is better than none, even some who espouse gNFB. 

The 12BY7 video pentodes was a cool way to get very wideband performance.  I think 5687's have the gm to keep the bandwidth, not sure they have the same gain.  Did he also change other things in the circuit?  I seem to recall there was some compensation also in the circuit and feedback paths.  It would seem one would need to revisit those for different driver tubes, not quite a plug'n'play.

Anyway, cool beans.

Your buddy who had the octal preamp, was it an aikido octal preamp or other octal?

[Freo-1]

Well regarding the deuce, it was an engineering marvel of its day.  I am not qualified to critique all the choices but there was a lot of tweaking to get very wideband performance and stable behaviour open loop so that feedback could be used without penalty.  Lots of cool local feedback loops. Many say local feedback is better than none, even some who espouse gNFB. 

The 12BY7 video pentodes was a cool way to get very wideband performance.  I think 5687's have the gm to keep the bandwidth, not sure they have the same gain.  Did he also change other things in the circuit?  I seem to recall there was some compensation also in the circuit and feedback paths.  It would seem one would need to revisit those for different driver tubes, not quite a plug'n'play.

Anyway, cool beans.

Your buddy who had the octal preamp, was it an aikido octal preamp or other octal?

It was an an aikido octal (4 6SN7's).  There are several of us around here who all use some variation of this circuit, and they all sound excellent.

Regarding the deuce, agree it was an engineering marvel in it's day (so was the Lafayette 550, another Hegman master!). The 5687 circuit used is very similar to the MFA 120 mono-blocks.