Pristine II restoration

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  • #391
    Nolafile
    Participant

    Ken,

    Thanks for the detailed listing. After examining the diagram it makes more sense. So the toroid is standing on edge and causes you to have to elevate the outer housing. Interesting. At least for the time being I’m sticking with the oem. As I want to get aquatinted with the original sound prior to stepping forward.

    I also notice that the later design has added -6db selections for the EQ settings. Which seems odd and I guess is related to the new design producing higher potentials. So I’ll have to research it, but I wonder if this has increased the older 88db efficiency rating?

    I see you’ve cleaned these banana jacks before. Remarkably I haven’t noticed these yet. Are they located recessed in the HV box? I notice the drawing refers to BJ at the connections on the box. They must be well hidden. I’ll have to have a close look tonight.

    Thanks,
    DD

    #429
    Nolafile
    Participant

    Good idea John. On the brilliance resistors I’m still debating ordering fancy Vishays. So far the engineering inquiry to them has not been followed up on. Half the input resistor order just arrived. The 50w resistors look pretty good. Idk how the original resistors were able to conduct the required input power with such small leads. These should definitely be a improvement. So this weekend the plan is to rework the backside of the EQ taps. Which at a minimum need to be dismantled, decarbonized and resoldered. Plus revarnish the side of the xformer laminations. Which burnt off causing minor light surface rusting. The input connections were also cooked loose and need a good polishing prior to reassembly. I may devise a point to point layout and discard the fiberglass input boards. As it all really need a bit more breathing room. After measurements on the larger replacement resistors. It looks like the input resistance will rise slightly from 7.5ish to 8.2ish ohms. And from 80 to 100 watt in rated wattage. Until recently I didn’t realize that these smaller panels require higher drive than the larger models. I normally run a 260wpc SS amp on my moderately inefficient mains. After this discovery I’m not sure if it is up to this task. But we shall see in a week or so. I think I may mount the interfaces on some filter stock 3/16″ or so off the bottom. And perhaps devise a topside vent. As I suspect a slight chimney flow wouldn’t hurt.

    DD

    #440
    Nolafile
    Participant

    Hey Fellas!

    Well here are the latest updates. The input circuit boards have been replaced with a tidy point2point install. I made solid copper heatsink/supports for the new power resistors. Which corrected the oem layout issues and really opened those resistors up to breath. I decided to stick with the oem 7 conductor twisted solid copper input wire. But paralleled a small silver stranded conductor to them. A few hours ago I got them back together and hooked up.

    One requires about 1/3 on the bias pot to obtain crackling. The other only around 1/5 and develops crackling along with popping. After applying audio it seems the 1/5 bias unit has a bit lower output than the other. Plus perhaps some panel issues. As u see moderate drive I can hear distortions and can see what appears to be a few areas where the membrane appears to be loose. So instead of HOS tonight I’m retreating back to the shop to pull the sock for a close inspection.

    Wish me luck as it seems I’m gonna need it.

    Cheers,
    DD

    #716
    Stphotog
    Participant

    Hey Ken cool write up…

    Hey where did u get a torroid for the pristine? Roger said the hot rod wont fit..

    I just replaced my caps today (only did the left so far. Even those i had to.put in a new spot.

    Also where did u get a plan for the diffuser?

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    #718
    Stphotog
    Participant

    Hey Ken cool write up…

    Hey where did u get a torroid for the pristine? Roger said the hot rod wont fit..

    I just replaced my caps today (only did the left so far. Even those i had to.put in a new spot.

    Also where did u get a plan for the diffuser?

    Not sure if i posted this twice

    #719
    yoshi
    Participant

    Hello:

    I sent the backplates to the factory for a Toroid 1 transformer installation. The new Toroid 2 will not fit in your backplate enclosure. Roger may still have the Toroid 1 in stock.

    Even with the Toroid 1 installed in the backplate, it would fit in the enclosure. I installed a 1/2” wooden square( 4 separate pieces, each one drilled to arrange with the housing mounting screws. This effectively raises the backplate to accommodate the deeper depth with the Toroid 1 transformer.

    Roger also did a minor parts upgrade to the crossover at a small cost while in there.

    I attached 2 pics on my backplates with the Toroid 1 and The new regulated bias supply I installed recently. You can see the height difference with the toroid 1 installed.

    With the new bias supply, you have to hack saw off one of the flanges(easy) and mount it on its side to fit in the small pristine backplate/ enclosure. I used a small cabinet bracket, screwed to the panel, 2 way tape and hot glue to mount it all together. This is only way it fits in.

    Good luck with your project!

    Ken

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    #722
    Stphotog
    Participant

    did you hear a difference with the new Torroid?

    #723
    Stphotog
    Participant

    Did you upgrade caps?
    I just did.
    Need to do the other side now.

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    #727
    yoshi
    Participant

    Hi:

    No, I did not upgrade the caps.

    On the toroid1, I did a series of updates close to the time, so I can’t really comment on the sound upgrade with the Toroid 1. I had experienced progressive improvements in bass extension, image depth and treble extension with all the updates. I am certain this update contributed to the performance enhancement.

    If you have not replaced the tweeter pot with a fixed resistor(ie. 4 ohm, 50 watt, non inductive), do it. Best bang for the I buck.

    A new regulated bias supply also made a difference, for some reason. It has greater output, and is ac voltage fluctuation independent. But, to my mind, it was an upgrade in overall sound performance. More of everything, so to speak.

    I would appreciate so details from you on the what the new caps upgrade are and where you soldered the in. What improvement did you hear with this change?

    Ken

    #731
    Stphotog
    Participant

    I just did the other side 😉

    #732
    Stphotog
    Participant

    A new regulated bias supply also made a difference, for some reason. It has greater output, A new regulated bias supply also made a difference, for some reason. It has greater output, and is ac voltage fluctuation independent. But, to my mind, it was an upgrade in overall sound performance. More of everything, so to speak.

    Where did you get it?

    #733
    Stphotog
    Participant

    I used Jansen Caps from Parts Connection (plus a coupling cap) and wired them in parallel. they do not fit on the board so I just hot glued them in place on the underside of the connection box (where red, yellow and black hook up)
    They sound good so far letting them burn in for hours before I do any critical listening.
    I also just added coupling caps to my FM 155 so I also did too many upgrades at the same time.
    I am interested in the torroidal and I will do the resister mod asap

    #734
    Stphotog
    Participant

    this?

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    #736
    Stphotog
    Participant

    or?

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    #740
    yoshi
    Participant

    Stphotog:

    If you look at my photo, I am using what I think is your first photo. Frankly, there will be lots of options at parts connextion. I just unwired out the variable pot and hot glued on the new resistor on top of it and solder it in. Simple. Bang, open up the top end. After some time now, I have no motivation to change the 4 ohm value.

    Ken

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