AVA Versa-Kit Line Preamp

Mark Korda · « **on:** 29 Jun 2011, 10:53 pm »

Hi.going thru my stack of stuff I found the instructions for building a AVA Versa-Kit Line Preamp that a freind printed out when he first got a computer.I think it was 1997.Has anyone out there ever built one or heard one?Also,if your reading this Frank V.,do you still have any parts hidden away,such as the PC-392 circuit board for sale?Thanks,just interested...Mark Korda.

aln · « **Reply #1 on:** 27 Jul 2011, 12:57 pm »

I bought one of these-a two channel affair with a toggle switch to go between two inputs. Haven't used it in years. A solid state buffer type preamp, I went back to my Van Alstine modified Pas-3x. Not sure if this helps-need more info-drop me a email.

Regards
AL N

avahifi · « **Reply #2 on:** 27 Jul 2011, 06:15 pm »

We can still supply you with a fully stuffed Insight+ stereo audio board for you to play with yourself for $125 plus $10 shipping.

This new AVA board can be ordered as a 20 dB gain line section, an RiAA phono preamplifier, a unity gain buffer, or a unity gain inverter. Not all at the same time of course.

You will need to suppy appropriate plus and minus 15V DC power supply connections and ground connections. The board has input and output connections and mounts with a couple of small metal L-brackets in any direction. It is about 4.25" x 2.25" and is a full ground plane shielded design, supplied with a pair of OPA627 socketed ICs and a pair of LME49600 current buffers as required for the specific application. Not all variations use all these active parts. It is complete including power suppy capacitors and all passive parts, ready to install and play in your pet chassis.

We can supply a regulated power supply board completely stuffed and ready to install for an additional $75.00 plus $10 shipping. This contains the diode bridge, raw suppy capacitors, and plus and minus 15V regulators necessary for the audio board.

You will need to add your own chassis and power transformer and appropriate controls and jacks.

The combination is very quiet and musical.

No satisfaction guarantee available on do it yourself projects.

Adequate documentation to allow you to make proper connections is included.

Regards,

Frank Van Alstine

P.S. This board can also be supplied as an outstanding headphone amplifier either with unity gain or with the gain you specify within reason. Same price.

krikor · « **Reply #3 on:** 27 Jul 2011, 06:47 pm »

Crap... why did I have to see this post.

Now I'm thinking an AVA preamp or headphone project may be in my near future. $200 plus shipping, just add a transformer and chassis (got a few laying around) sounds very reasonable!

WC · « **Reply #4 on:** 27 Jul 2011, 07:50 pm »

Frank,

If I understand the AVA audio board offer, I would choose the board with the RIAA phono preamplifier, that would only be able to make a phono preamp and not have a line preamp and phono preamp together on the same board. I would need two boards the 20dB gain line section and the RIAA phono preamplifier? Would the power supply board be able to work for both cards?

avahifi · « **Reply #5 on:** 27 Jul 2011, 08:33 pm »

Correct, you would need separate two channel audio boards to provide both phono and line functions.

The power supply board has adequate current capacity for several of these new Insight+ boards, provided your power transformer is appropriate.

We would suggest the Antek AN-0215 as an appropriate power transformer available at low cost.

Sorry, no DAC board planned for do it yourselfers, its a bit layout sensitive, requires a separate analog filter/output board and a separate three stage regulated power supply board, and would be much more expensive.

Regards,

Frank Van Alstine

Mark Korda · « **Reply #6 on:** 28 Jul 2011, 06:56 am »

Dear Frank,thanks for replying.I don't have the cake to take on the project I wanted to in 1997 right now.I don't want to waste your time,but when the Versa Kit Line Preamp instructions for do it your self came out,any one could of constructed it,because the instructions were perfect!10 years ago,sitting in this same apartment which I still live I built a headphone amp kit from Germany called the (Corda).The instructions were terrible,but the head of the company stuck with me on e-mail and got me thru it.I made a copy of a few pages of the Versa-Kit instructions and sent them in the mail to the Deutchland,to show him how to have less dummys like myself,out of his hair.The directions were outstanding for the Versa-Kit.Another good person e-mailed me about the board he had for sale,but with out proper instruction I'm toast.Thanks for writing me back,one of my bucket dreams is to be able what you do...sincerely Mark Korda

rcag_ils · « **Reply #7 on:** 28 Jul 2011, 02:14 pm »

Kudo to Frank for making these kits available, it makes this hobby more interesting.

dB Cooper · « **Reply #8 on:** 28 Jul 2011, 03:01 pm »

The instructions are available in the back issues of Audio Basics available on the AVA website. All the configurations are covered. Probably comparable to ones that would be furnished with the new boards. Just all about all that would be needed for a project of this scale is a pictorial diagram. I would expect the new circuits would presumably have more modern performance.

I would like to know if projects built on the PC-392 board would benefit from "chip rolling" with the opamps that are being used in current production (my board has the Analog Devices' AD843 chips).

jmc207 · « **Reply #9 on:** 28 Jul 2011, 03:03 pm »

Quote from: rcag_ils on 28 Jul 2011, 02:14 pm

Kudo to Frank for making these kits available, it makes this hobby more interesting.

+1 Thanks Frank!

avahifi · « **Reply #10 on:** 28 Jul 2011, 06:46 pm »

Chip rolling on the old (and out of production and unavailable) PC-392 board is not recommended.

Certain biasing and layout functions for the old chip design probably would not be appropriate for the OPA627, especially when combined with an LME49600 current amplifier.

Frank

dB Cooper · « **Reply #11 on:** 30 Jul 2011, 07:39 pm »

I am glad there is still a DIY option; kit built audio has all but disappeared. I have the kit "itch" again lately but there is virtually nothing to build

Even the PAT-5 rebuild kit seems to be gone. Thinking about the Millett MiniMax headphone amp just to scratch the itch.

rcag_ils · « **Reply #12 on:** 3 Aug 2011, 01:52 am »

Well, got my insight buffer installed in my "one off" Super Pas 3 at my under-equipped home lab.

I'd like to install it further away from the phono board per Frank's recommendation, but the regulated PS is in the way, and I don't want to butcher up the chassis, that's really the best I can do and it's reversible if needed. I guess I could have installed it on the other side of the phono board, but it'd be just about as close to the phono as it is now, and I'd like to reserve that space for the phono buffer if the power supply allows.

The rest of the wiring will have to be done at my work lab, but it should be easy.

WC · « **Reply #13 on:** 3 Aug 2011, 06:43 pm »

This Preamp kit would be for the SS Insight type. Is there a possibility of a tube preamp kit? Or is that the Super PAS Three rebuild kit?

trebejo · « **Reply #14 on:** 3 Aug 2011, 10:18 pm »

rcag, that is some sweet work there, congratulations!

rcag_ils · « **Reply #15 on:** 4 Aug 2011, 03:08 pm »

Finished this late last night, did a smoke check and it worked fine.

I started listening early this morning, wow, the bossy sound from Mark Knopfler Gibson Les Paul really stood out, more detail in the background (more instrument that were not so obvious before), the music flows better, more bass extension as I remember how it sounded before.

Well worth the effort.

avahifi · « **Reply #16 on:** 4 Aug 2011, 03:47 pm »

What this board is doing is providing a very easy to drive and consistent high input impedance load to the output tubes letting them run much more linearly, and providing an ultra low distortion, ultra fast high current low output impedance drive to the real world. This eliminates any possible interaction between the tube output section and real world loads while improving the musical performance of the tube section at the same time.

This Super Pas Three preamp has some "one off" revisions done here before it was sold to the client. We used it as a "what if" to see if it would be worthwhile doing a complete power supply board redesign for our standard Super Pas Three rebuild kit. The "what if" provides an active regulated high voltage supply instead of the standard high capacity passive supply board furnished with the Super Pas Three rebuild kit.

We decided that the improvements with the active regulated supply were significant, but that due to the declining number of available stock Dyna PAS units out there to drawn upon now, that the cost internally to redesign and re-tool the power supply board, along with the cost to do a major rewrite on the step by step kit manual instructions probably would never make the project cost effective for us to attempt. We only have so many resources and there are always more important ideas to pursue.

So this remains a special one off unit, and we are happy that adding the output buffer made it even better than before.

Nice work!

Frank Van Alstine

rlee8394 · « **Reply #17 on:** 4 Aug 2011, 05:51 pm »

Frank,

Assuming some of us want to add the buffer to our Super Pas Three, would the supply voltages come from the current filament supply of the power supply board?

Ron

avahifi · « **Reply #18 on:** 4 Aug 2011, 09:43 pm »

Yes the buffer circuits use the available + and - 12V heater supplies. These are further decoupled and filtered by a pair of 3300uF 16V lytics on the buffer board, along with lots of high frequency decoupling too. The result is very quiet and stable performance.

Frank Van Alstine

rcag_ils · « **Reply #19 on:** 13 Aug 2011, 07:05 pm »

Here it is. After listening to the "one off" Super Pas 3 with the insight line buffer for about three weeks, I can say that there is a solid improvement over before the mod. The line input (CD) has more details and air in the vocal, background instrument, more bass extension, and the main instrument stand out and has more of a three dimensional sound.

I haven't listened to the phono input of this preamp enough to make comparison of what it sounded like before and after the mod. So I played some vinyl with it after the mod, and the sound suggested that it retained the same characteristics as the line input, more detail, more bass extension. The most noticeable is the track "Idiot wind" in Blood on the Tracks, you can actually hear the keyboard player trying to catch up with Dylan's vocal.

I've decided to push it to the limit and got the phono buffer from Frank, just had it installed and will start the wiring soon.