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Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Dynaco VTA tube amp kits, all products and all products

    Tubes 4 HiFi Preamps



    Posts : 22
    Join date : 2008-12-22

    Tubes 4 HiFi Preamps

    Post by merlot on Sun Jan 16, 2011 3:43 pm

    I'm interested in building a preamp. I've already built an ST-70 and two ST-120s. Later in the year, I'll consider a pair of M-125s. This is a great forum by the way - I really enjoy reading the posts.

    I see lots of discussion about the power amps but very little regarding the preamps (SP-6, SP-8, PAS3, PAS3-Z). I gather from the site only the PAS3 and PAS3-Z are offered now. Does anyone have any experience with it? Thoughts?

    What are the differences between all these models? Are the SP models out of production?

    Probably inappropriate, but are there other preamp kits out there?

    Appreciate any thoughts....

    Tube Nube

    Posts : 620
    Join date : 2008-12-06
    Age : 53
    Location : Calgary, AB

    Re: Tubes 4 HiFi Preamps

    Post by Tube Nube on Sun Jan 16, 2011 6:44 pm

    Hi Merlot,

    Bob did a review of Roy's SP8 SE, I think was the model's designation, about a year back. I'd be interested also to know what the differences are between that amp, and the latest designation, but my understanding is that the major difference is that it was a 2 pc board amp in the SP8, and it's been broken down into a 3 board system in the current iteration for greater flexibility and choice of options etc.

    I've been working on building one of these VTA pre amps -- sorry, I'm not even sure what model it is. : /

    But back to the comparison. I'm currently using a Transcendent GG (grounded Grid) pre amp, which came highly recommended. Bob used to own one himself and had a high opinion of it too, as I recall.

    But when he reviewed Roy's VTA pre-amp, he was comparing it against two commercial products costing, iirc, $3k and $6k -- and he found it superior to the former, and regarding the latter, better in some respects, but not as good in others.

    So, at the end of the day, for less than a grand, to think you can have a pre-amp that holds it's own with commercially produced hi fi in the $6k range is... well... THAT is impressive!

    Trying to read between the lines, and maybe I read to much into those white spaces, but my inference was that Bob thought more highly of the VTA than the TS GG.

    That's a good thing, I think, because highly regarded as the GG is, there's something about it that I don't like. Now I wish I had much more experience with many more pre amps but combining my own dissatisfaction and what I read about the GG on the Transcendent forum, I have come to believe there is a certain coldness, or analytical-ness to the sound of the GG.

    I'm much looking forward to having my VTA Pre finished so I can do a direct comparison of my own. I very much suspect, however, that the VTA will clobber the GG.



    Posts : 1268
    Join date : 2008-11-30

    preamps from Tubes4HiFi

    Post by tubes4hifi on Mon Jan 17, 2011 2:22 pm

    my preamp offerings are under continual change in order to make the best product for the price.
    While the SP8 is officially discontinued, I have had a few customers special order it from me.
    The PAS3 upgrade and the Zmod are the same PCBs and are the identical circuit to the older SP8 but without B+ regulation, and on 3 separate PCBs (to fit the PAS3) rather than one single PCB.
    Not well known but I also sell alot of AIKIDO preamps which is the best circuit I've auditioned in all my years, I don't have it listed on my web site but sell them all the time.
    I hope to have the time (between keeping up with orders and emails and everything else)
    to completely revamp my preamp page within the next 2-4 weeks, and will have 3 line stage amps and 4 phono stage preamps offered, as well as 4 different versions of power supplies for preamps.
    This gets confusing for "newbies" but gives the experienced builder exactly what they want with no extras. I had considered making another single board preamp but prefer the flexibility of offering the separate parts for totally custom configurations for each customer.
    If you don't need a phono board, then why pay extra for it?
    Also another big consideration is that by the time you get all the parts to build the preamp, the circuit boards themselves turn out to be the least expensive part of the project.
    You can build a simple inexpensive preamp for around $500, but amazingly, for about $100 more you can use the best possible circuit, everything else remains the same (chassis, controls, transformers, etc).
    The grounded-grid preamp is a decent circuit in a cheap box and a crummy power supply, for $500.
    The foreplay is worth about $250 but they charge $550 for it with a homemade wood box.
    IMHO you can't beat my Zmod preamp at $550 which may be going up in price, and for $700 I can sell you a preamp better than anything you can find at triple that price.


    Posts : 17
    Join date : 2010-12-21
    Location : Calgary, Alberta

    I built a Tetra/Aikido preamp from Roy

    Post by Disles1 on Tue Jan 18, 2011 12:22 pm

    I became interested in the ST-120 because I previously built a Tetra phono/Aikido line stage preamp with Roy's help. Although I haven't the experience to compare it with others, it sounds fabulous with loads of detail, clarity, proper timbre, etc. As Roy mentions on his site, the cost of the finished preamp will depend greatly on the quality of the various parts you choose to use. One item I heartily recommend is the stepped attenuator that Roy sells. It is a quality piece at a reasonable price.

    I don't think you can go wrong listening to Roy's suggestions.


    Posts : 22
    Join date : 2008-12-22

    Re: Tubes 4 HiFi Preamps

    Post by merlot on Wed Jan 19, 2011 10:31 pm

    Thanks for the responses. Once the website is redesigned I'll follow-up. I'm really quite interested in building my own pre-amp but I'll need some guidance on the merits of the various components.

    Thanks again.


    Posts : 1268
    Join date : 2008-11-30

    Re: Tubes 4 HiFi Preamps

    Post by tubes4hifi on Thu Jan 20, 2011 1:36 am

    due to a large amount of requests, I'm bringing the SP8 preamp circuit back, AND, it's improved,
    with a slightly revised PCB for easier connections, and a complete ground plane
    under the amp circuits. Also MANY new offerings, most of these are ready to go now.
    Check out these two webpages for info . . . SP8 preamp many new preamps


    Posts : 4
    Join date : 2011-01-04

    Finished building the "new" Z mod from Roy...

    Post by crxman on Tue Feb 15, 2011 1:52 pm

    Hi all,

    I have an "original" ST-70 that Sal Brisindi had looked at and put back to almost stock. Some of the caps have been upgraded and he changed it back to tube rectification. It is running on on old "stock" PAS 3 and sounds good. I recently received a Bob Latino ST-120 and I had preamped by a "stock" PAT 5. I've always wanted to attempt to build a kit, so my first attempt became Roy's Z-Mod. It came with the custom chassis that was beautifully etched on the front and back panel. My kit has the PC5, PC6, & the regulated PS-Zmod boards. I finally completed the kit, with some much needed advice from Roy and paired it with the Latino ST-120. When I was using the PAT 5, I had to run an extra set of smaller speakers to bring out the high end. With the new SP-6 those were no longer needed, as my modified Wharefdale ST70's came to life. This was my first kit, probably not the easiest to build, but well worth the time and effort. It is certainly something that I can take pride in. Thanks again to Roy.

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