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    SP12 in a PAT 4 Chassis Yes or No

    richtp
    richtp

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    Post by richtp on Sun Feb 09, 2020 2:58 pm

    I am contemplating putting my new SP12 board in a Dynaco PAT 4 Chassis. I really like the idea of keeping the Dynaco look to go with my amps but feel a little guilty about gutting the PAT. It’s not pristine but does work. What would you all do? Yea or nay!SP12 in a PAT 4 Chassis Yes or No 78f78d10
    SP12 in a PAT 4 Chassis Yes or No C4006b10
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    stewdan

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    Post by stewdan on Sun Feb 09, 2020 4:09 pm

    Some years back Roy offered an SP12 Line Preamp in a PAT4 case and I bought it from him.

    I opted for him to install a plain vanilla aluminum front panel with Source-Volume-Balance Knobs and 2 Switches, Power and Source-Tape.

    The unit also has a reworked back panel with new RCAs.

    Sound-wise this has been one of my best purchases and I have never looked back on the purchase.

    Have fun!!


    richtp
    richtp

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    Post by richtp on Sun Feb 09, 2020 5:16 pm

    Stewdan I think I remember seeing the post about that at some point. But now the pics won’t load. I would love to see pics if you have any.
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    stewdan

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    Post by stewdan on Sun Feb 09, 2020 10:57 pm

    Hi Rich --- I dont have any since I did not save any of Roy's pictures. I could take some, but I have never posted pictures here before.

    What would you like to see pictures of? Exterior? Interior?

    Let me know and I will see what i can do.

    Stew
    richtp
    richtp

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    Post by richtp on Mon Feb 10, 2020 5:44 am

    Stew, pics of the interior would be great if it’s not to much trouble. I am curious how the board and transformer are laid out. I still have not made up my mind if I will use the pat or build a new chassis.
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    audiobill

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    Post by audiobill on Mon Feb 10, 2020 6:59 am

    If you decide to do this, consider disconnecting all unused switches and replace jacks, selector switch, volume control, etc with parts from Erhard Audio. May as well maximize performance by doing so.
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    stewdan

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    Post by stewdan on Mon Feb 10, 2020 10:02 am

    Rich --- Some description in lieu of pictures, which should help.

    My SP12/PAT4 has the 3 Knobs on the left side of the face-plate. The PCB is behind the knobs, also on the left side.

    I also have 2 old style Hammond Transformers laid out front to back on the right side of the PCB and the chassis.

    The power switch is on the right side of the face-plate and in front of the Transformers.

    The source/tape monitor switch is mounted underneath the knobs.

    On the back side I have RCAs for 4 pairs of Line Inputs, Tape In/Out, and 2 pairs of Outputs.

    Roy kept the fuse holder on the Back and the 4 AC Outlets.

    Oh, there is also a new selector switch (Radio Shack type) and wiring, and 2 alps RK27 type Volume and Balance Controls (100K)

    Any questions, just ask.
    Stew

    richtp
    richtp

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    Post by richtp on Tue Feb 11, 2020 6:53 am

    Thanks Stew! That is kind of how I was planning on laying it out. I already have a few of the radio shack type 5 position selector switches laying around. And you answered one question I have not asked yet, the 100k pots.

    Audiobill thanks for the advice. It’s good advise and although I may cheat a bit due to impatience I plan to use new potentiometers and switched if possible.

    I have decided to go for it and gut the PAT 4. It’s pretty rough anyways and has spent most of the last 10 years on a shelf in the closet. So why not. I plan to build a wood (Poplar) case for it to match the speakers I built. If I get home from work before bedtime today I will start gutting it!
    DavidR
    DavidR

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    Post by DavidR on Tue Feb 11, 2020 11:30 am

    Do it. It looks cool.
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    stewdan

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    Post by stewdan on Tue Feb 11, 2020 4:23 pm

    richtp
    richtp

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    Post by richtp on Tue Feb 11, 2020 7:39 pm

    Stew...Wow! Thanks for going through the trouble with posting the pics.i really appreciate that. It looks pretty cool. And is pretty much how I was thinking of laying it out. Not there there is a lot of room for options. I like the front panel as well. Wish I knew how to silkscreen my own nomenclature on the front panel. I always wanted my volume control to go to 11 instead of 10.
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    stewdan

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    Post by stewdan on Tue Feb 11, 2020 8:36 pm

    Rich --- There are Letter and Number Transfers that can be used to label a metal face plate and can be found listed on eBay. They come in all sizes and fonts.

    If I remember correctly, I think that is how Roy did the Front Panel.

    Stew
    richtp
    richtp

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    Post by richtp on Tue Feb 11, 2020 9:44 pm

    Stew, I never thought of that. I remember seeing all kinds of stuff like that for model railroads at hobby stores. Maybe I will see if it will work. Not sure if I have the patience though. Might have to con the wife into helping with that.
    richtp
    richtp

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    Post by richtp on Tue Feb 11, 2020 9:53 pm

    So it begins!SP12 in a PAT 4 Chassis Yes or No E9c5fe10
    SP12 in a PAT 4 Chassis Yes or No 1fbae410
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    stewdan

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    Post by stewdan on Wed Feb 12, 2020 11:46 am

    Have fun!!!

    Stew
    aguaazul
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    Post by aguaazul on Thu Feb 13, 2020 12:50 am

    I kludged the VTA ZMOD Preamp inside of the PAT 4 Chassis. Roy sent me the last Gold RCA I/O Board plus the Front Panel Express file(s) for the PAT 4.

    I can share these Front Panel Express file(s) online of anyone wants to use them.

    Cheers,

    Bluewater



    VTA PAT 4 Back

    VTA PAT 4 Back2

    VTA PAT 4 ZMOD Inside

    VTA PAT 4 Inside from Side

    VTA PAT 4 ZMOD Front


    Last edited by aguaazul on Thu Feb 13, 2020 11:46 am; edited 3 times in total (Reason for editing : Fixed Duplicate Link)
    richtp
    richtp

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    Post by richtp on Thu Feb 13, 2020 10:36 am

    Bluewater I get an error notice when I try to open the links. How do you like the ZMOD kit? I was contemplating getting either the ZMOD kit or the tone control kit for my PAS before I went this direction.

    Rich
    aguaazul
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    Post by aguaazul on Thu Feb 13, 2020 12:28 pm

    richtp wrote:Bluewater I get an error notice when I try to open the links. How do you like the ZMOD kit? I was contemplating getting either the ZMOD kit or the tone control kit for my PAS before I went this direction.

    Rich

    Hey Rich,
    Sorry about the links. I think I fixed them.

    I dipped my toe in the VTA preamp arena with the ZMOD inside a PAS 3. Then I wanted tone controls, so I did drop in the TCLA inside of my PAS 3.
    I wish I had never tore my PAS 3 apart.

    My neighbor had 3 PAT 4's he sold me for parts, so I rolled the ZMOD into a PAT 4. Both were fun to run.

    The ZMOD PAT 4 I use as a spare / test preamp. Our main preamp for stereo listening is Don Sachs's version of the SP14

    Bluewater
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    Dale Stevens

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    Post by Dale Stevens on Thu Feb 13, 2020 5:09 pm

    Rich, If u're gonna discard the PAT 4 hardware and stuff I would like to get. If so then just PM me. Dale
    richtp
    richtp

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    Post by richtp on Thu Feb 13, 2020 7:12 pm

    Bluewater, it looks nice. I rebuilt my pas about 10 years ago? It is sort of stock. I did replace the boards with VTA stock boards. At the time I was thinking of using the ZMOD kit but decided not to because at times I like tone controls. I ran it for a long time with the tone controls bypassed. Recently I hooked them back up and made a new power supply board copied from the One SDS labs sells. I have a love hate relationship with my PAS haha. I put more into it than it’s worth and some days it sounds fine to me and other days it just sounds off. But it’s the first tube preamp I tore into.

    I can’t wait to listen to the SP12. But I’m working on a plan and waiting on parts.
    richtp
    richtp

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    Post by richtp on Thu Feb 13, 2020 7:14 pm

    Dale, I wouldn’t discard anything. But when I’m done I will offer up whatever is left over to anyone that can use it. I think I have a few extra PAT boards around here as well if I can find them.
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    Dale Stevens

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    Post by Dale Stevens on Thu Feb 20, 2020 4:59 pm

    Rich, keep updating on your build; I think i'll do this later on. That way, I can rack this in my custom 19 inch. I have a rack bracket that fits the 4.
    You're not doing a phono stage?? Dale
    richtp
    richtp

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    Post by richtp on Sat Feb 22, 2020 7:25 am

    Dale. The chassis is to small to fit a phono stage. I thought about making an extension for the back panel to make the whole chassis deeper or putting a small solid state phono stage on the back panel but at this point it seem the best option is a separate phono stage.
    I am also thinking about sticking with a loudness switch circuit similar to what’s in the PAS. I have always liked the loudness function on my amps and preamps when I’m listening at low volume.
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    rjpjnk

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    Post by rjpjnk on Sun Feb 23, 2020 9:30 pm

    I have the SP12 with the PH12 phono stage and am very happy with them. You could fit the PH12 phono board in that PAT if you made an external box for the transformer I suppose. Not sure if that is okay or not noise and safety wise. Just a thought.

    Loudness control should work fine if you have the right pot with tap.
    Wotan
    Wotan

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    Post by Wotan on Mon Feb 24, 2020 12:31 pm

    If I still had my PAT-4 I would do it.  I'd replace all the pots, switches and jacks, though, they were junk.  For some reason David Haffler believed parts quality didn't matter.  Nice chassis, though.

    Signal wire routing and grounding needed improvement.  When I had a Rabco SL-8E I had channel to channel hum I could never quite get rid of (other than throwing the mono switch) until I replaced the pre, which is why I no longer have it.  High end tastes on a budget back then.  No hum with the AR and probably most modern TT's.  I never got the grounding/ground loop thing sorted, just moved on.

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