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  1. #1

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    Default Dreadnought Assembly Questions

    I am in the process of building my first dreadnought (AL Y236906 and Neutrik NL4's) and had a of couple of questions. I have read that the wiring should be as follows:

    Red/Yellow (right pin) to 1+
    Black/Orange (right blade) to 1-
    Grey/Brown (left pin) to 1+
    Blue/Violet (left blade) to 1-

    Does this mean that once assembled the right speaker has to hooked up to the Neutrik plug with the red/yellow and black/orange combination and the left speaker has to be hooked up the Neutrik plug with the grey/brown and blue/violet combo? I wouldn't think it would be directional like that but I'm just learning this stuff.

    Also, is the transformer just mounted by drilling a hole through the bottom of the dynamatted aluminum box, then mounted using the supplied mounting pads and hardware? Or is there something else that should be between the transformer and the bottom? Thanks

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    Does this mean that once assembled the right speaker has to hooked up to the Neutrik plug with the red/yellow and black/orange combination and the left speaker has to be hooked up the Neutrik plug with the grey/brown and blue/violet combo?
    Yes.

    Also, is the transformer just mounted by drilling a hole through the bottom of the dynamatted aluminum box, then mounted using the supplied mounting pads and hardware? Or is there something else that should be between the transformer and the bottom?
    Basically yes, but I would suggest using non-ferrous hardware such as stainless steel or brass.
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    Jesse, can you elaborate on the reason for dedicated left and right?
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    So, what are the downsides to hooking the Dreadnaught up backwards and using a non-ferrous enclosure or hardware? I've been running an AL-based Dreadnaught for well over a year and didn't know to pay attention to which set of posts each speaker was hooked to. (I'll definitely take a close look at that now.) But either I just got lucky and hooked it up right by accident, or I can't hear much difference due to having hooked it up wrong. I haven't switched the connections on the Dreadnaught, but I do go back and forth between the Dreadnaught and a direct connection between the speakers occasionally, and both sound nearly identical.

    Also, I'm using a steel enclosure that is plenty ferrous... magnets stick to it great. Is there some reason for having only non-magnetic stuff around the transformer?

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    As long as the primary transformer windings go to one speaker, and the secondary transformer windings go to the other speaker, left and right aren't critical. You do need to keep the color codes paired-up, and pay attention to + and - .

    These transformers are NOT symmetrical, so the primary and secondary windings aren't identical. Theoretically, this should result in somewhat greater SDA volume in one channel, and somewhat less SDA volume in the other...but DK and others don't seem to be bothered by this asymmetry. I haven't put my Dreadnought together yet, and for that matter I'd have to buy different speakers to use it at all--so I can't give you any experienced-based wisdom regarding the transformer windings.

    Magnetic hardware has the potential to change the specs of the transformer. Non-magnetic (which is almost but not quite the same as non-ferrous) won't screw with the magnetic force of the transformer. Stainless hardware is (USUALLY) non- or slightly-magnetic, but it's still ferrous.

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    I assume that the bolt, nut, washer and metal dish that AL shipped with the transformer are non-ferrous, but I will check with them just to be sure. They also sent a metal sleeve/shield to encircle the transformer. I just have to secure it in some fashion- zip ties or duct tape or something. If the right and left connections are critical then I'll have to identify L & R on the box somehow.

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    Quote Originally Posted by Schurkey View Post
    As long as the primary transformer windings go to one speaker, and the secondary transformer windings go to the other speaker, left and right aren't critical. You do need to keep the color codes paired-up, and pay attention to + and - .

    These transformers are NOT symmetrical, so the primary and secondary windings aren't identical. Theoretically, this should result in somewhat greater SDA volume in one channel, and somewhat less SDA volume in the other...but DK and others don't seem to be bothered by this asymmetry. I haven't put my Dreadnought together yet, and for that matter I'd have to buy different speakers to use it at all--so I can't give you any experienced-based wisdom regarding the transformer windings.

    Magnetic hardware has the potential to change the specs of the transformer. Non-magnetic (which is almost but not quite the same as non-ferrous) won't screw with the magnetic force of the transformer. Stainless hardware is (USUALLY) non- or slightly-magnetic, but it's still ferrous.
    When I wired mine up I did pay close attention to the polarity and getting the leads paired correctly. If right vs left just comes down to one SDA side being louder it almost seems like you'd want to swap back and forth to get the best (or at least most innocuous) effect depending on room placement.

    I do remember seeing a thread quite a while back discussing aluminum vs steel as an enclosure, but I didn't remember there being a definitive outcome in terms of one being noticeably superior. My transformer didn't come with any special shielding, but the fact that they are now providing shielding seems to suggest AL thinks it could be an issue. At the time I got my enclosure though, it was the same one DK had used for one of his builds, so I figured, good enough for DK, good enough for me.
    Last edited by On3s&Z3r0s; 04-22-2014 at 09:34 PM.

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    Yes correction, I meant non-magnetic....thanks Schurkey.

    Quote Originally Posted by westmassguy View Post
    Jesse, can you elaborate on the reason for dedicated left and right?
    As stated, the primary windings go to one speaker, the secondary windings go to the other.

    To keep it as simple as possible in order not to confuse anyone the following works perfectly and there is no reason to change it.

    Red/Yellow (right pin) to 1+
    Black/Orange (right blade) to 1-
    Grey/Brown (left pin) to 1+
    Blue/Violet (left blade) to 1-


    stogie, put a magnet to the hardware. If it sticks to any of it you don't want to use it.
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    If right vs left just comes down to one SDA side being louder it almost seems like you'd want to swap back and forth to get the best (or at least most innocuous) effect depending on room placement.
    No one that I'm aware of has noticed an imbalance.
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    Cool, y'all freaked me out with that right/left thing. My A1 is buried in the bottom cabinet of a china hutch between the speakers. I have no idea which speaker is cabled to which set of posts. This saves me half an hour of digging it out and unscrewing two dozen hex screws to find out.

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    Quote Originally Posted by On3s&Z3r0s View Post
    When I wired mine up I did pay close attention to the polarity and getting the leads paired correctly. If right vs left just comes down to one SDA side being louder it almost seems like you'd want to swap back and forth to get the best (or at least most innocuous) effect depending on room placement.
    Quote Originally Posted by F1nut View Post
    No one that I'm aware of has noticed an imbalance.
    Agreed. I had hoped to goad DK into using his Magic Scope to analyze the electrical imbalance of these "isolation transformers" but he didn't take the bait like I expected.

    These transformers are all intended to accept 115 or 230 volts input on the primary windings, and to provide 115 or 230 volts output on the secondary side. Since all transformers have some amount of "loss", the manufacturer compensates by adding some extra winding to the secondary windings, so the losses of the transformer don't show up as reduced voltage on the secondary windings. We Polkies are using the transformers for an entirely different purpose, we're transferring power BOTH directions--from primary to secondary, but also from secondary to primary. Since the transformer isn't symmetrical, what works to prevent voltage loss in one direction makes the voltage loss worse in the other direction. But since I haven't actually built one, and I don't have the Electrical Engineering background (or the 'scope) to run tests, I am just making guesses that the SDA signal is compromised. Yes, nobody who's using one of these is complaining of SDA signal imbalance. Maybe that's good enough.

    Quote Originally Posted by On3s&Z3r0s View Post
    I do remember seeing a thread quite a while back discussing aluminum vs steel as an enclosure, but I didn't remember there being a definitive outcome in terms of one being noticeably superior. My transformer didn't come with any special shielding, but the fact that they are now providing shielding seems to suggest AL thinks it could be an issue. At the time I got my enclosure though, it was the same one DK had used for one of his builds, so I figured, good enough for DK, good enough for me.
    Aluminum would be preferred over steel--as I understand it--based on electrical conductivity. Better conductivity = better shielding. Copper would be better still, and I suppose that means that silver would be pretty much optimum.

    I intended to use copper for my housing until I started pricing copper sheet. Holy crap, has copper pricing gone up.

    I have a clever and artistically satisfying aluminum housing, of which I'll post pictures in about ten years when I've actually assembled my Dreadnought into it.

    Quote Originally Posted by F1nut View Post
    Red/Yellow (right pin) to 1+
    Black/Orange (right blade) to 1-
    Grey/Brown (left pin) to 1+
    Blue/Violet (left blade) to 1-
    I will be building one of these...someday. (I'll have more motivation to build it directly after buying speakers it can be used with.)

    I know in my head how it's going to be wired, but just for clarity--please explain the significance of the "1". I get the + and the -, but I don't get the significance of the "1".
    Last edited by Schurkey; 04-22-2014 at 11:03 PM.

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    I had hoped to goad DK into using his Magic Scope to analyze the electrical imbalance of these "isolation transformers" but he didn't take the bait like I expected.
    LOL

    please explain the significance of the "1". I get the + and the -, but I don't get the significance of the "1".
    Ah yes, the OP copied that from one of the Dreadnought build threads where SpeakOn connectors were used, hence the "1".
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    Yes, the 4 pole Neutrick SpeakOn connectors have tabs that are labeled 1+, 1-, 2+, 2-. Of course you only use one pair of the tabs, but the 4 pole version (per their specs) has a wider collar ID (14mm), therefore it will accept a larger gauge wire than the 2 pole version. Which brings me to my next question. Which "reasonably priced" cable/wire is recommended for the interconnect? I have read somewhere that DK used Monster Z3 (I believe) in one of his builds, but I can't find that available anywhere. Also I read that MIT cable was used but was very hard to work with. I was thinking any OFC 10 gauge speaker cable might work. Any ideas? thanks

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    Quote Originally Posted by F1nut View Post
    Yes correction, I meant non-magnetic....thanks Schurkey.



    As stated, the primary windings go to one speaker, the secondary windings go to the other.

    To keep it as simple as possible in order not to confuse anyone the following works perfectly and there is no reason to change it.

    Red/Yellow (right pin) to 1+
    Black/Orange (right blade) to 1-
    Grey/Brown (left pin) to 1+
    Blue/Violet (left blade) to 1-


    stogie, put a magnet to the hardware. If it sticks to any of it you don't want to use it.
    So in essence, it shouldn't matter left vs right, and long as the internal wiring is correct? It's a one to one isolation transformer, it should be bi-directional.
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    Quote Originally Posted by westmassguy View Post
    So in essence, it shouldn't matter left vs right, and long as the internal wiring is correct? It's a one to one isolation transformer, it should be bi-directional.
    You could connect either the left or the right channel to the primary windings, and the other channel to the secondary windings. You will have to keep the color-coded wire pairs of the transformer correct, and you will have to pay attention to + and -.

    The transformers are NOT 1:1, but they're close to 1:1. I'm thinking that the primary wire gauge is different from the secondary wire gauge. That's the basis for my comment about the transformers being asymmetric, which has to screw with the SDA signal, although perhaps inaudibly.

    If I were running a group-buy of transformers, I'd tell the manufacturer that I wanted the primary and secondary windings to be identical--same wire size, same number of turns. That's NOT how the typical "isolation transformer" is built, so it'd be a custom-job.
    Last edited by Schurkey; 04-23-2014 at 03:37 PM.

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    Quote Originally Posted by Schurkey View Post
    You could connect either the left or the right channel to the primary windings, and the other channel to the secondary windings. You will have to keep the color-coded wire pairs of the transformer correct, and you will have to pay attention to + and -.

    The transformers are NOT 1:1, but they're close to 1:1. I'm thinking that the primary wire gauge is different from the secondary wire gauge. That's the basis for my comment about the transformers being asymmetric, which has to screw with the SDA signal, although perhaps inaudibly.

    If I were running a group-buy of transformers, I'd tell the manufacturer that I wanted the primary and secondary windings to be identical--same wire size, same number of turns. That's NOT how the typical "isolation transformer" is built, so it'd be a custom-job.
    Schurkey, I understand what you're saying. I've always heard them referred to as one to one. Any difference must be inaudible though, with all the critical listeners we have here. If it weren't we'd have heard about by now.
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    For the 1000VA tranny the primary is 18AWG and the secondary is 16AWG, both rated at 115V and 4.35A. I don't know the AWG for the 800VA tranny, but it is also rated at 115V both and 3.48A. They are sold as 1:1 trannies. It's entirely possible that more 18AWG is used to balance out the sides. Regardless, no one has been able to hear any imbalance. Speaking for myself, if there was one I am 100% confident I would notice it.
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    Quote Originally Posted by Schurkey View Post
    Agreed. I had hoped to goad DK into using his Magic Scope to analyze the electrical imbalance of these "isolation transformers" but he didn't take the bait like I expected.
    You also asked this question in this thread from 2012 (posts 167-174):

    The-AI-1-Dreadnought-Project-Pt.2-Upgrade-to-1000VA-Transformer

    This subject was first addressed in posts 62-71 of this thread:

    The-AI-1-Dreadnought-Project-Pt.1

    When I measured the left and right stereo and dimensional outputs of the Y236906 800VA transformer in 2008, there was a few percent difference in the outputs of each direction, but it certainly could not be considered as an "imbalance".



    Quote Originally Posted by DarqueKnight View Post
    In terms of dB, the differences in voltage amplitudes between channels are:

    60 Hz

    0.12 dB stereo, 0.26 dB dimensional.

    1000 Hz

    0.38 dB stereo, 0.39 dB dimensional.

    With all of the things going on in a stereo sound field, it is not difficult for me to accept that most people would not notice a difference of 0.1 dB to 0.4 dB difference in sound level between channels.
    Quote Originally Posted by Schurkey View Post
    These transformers are all intended to accept 115 or 230 volts input on the primary windings, and to provide 115 or 230 volts output on the secondary side. Since all transformers have some amount of "loss", the manufacturer compensates by adding some extra winding to the secondary windings, so the losses of the transformer don't show up as reduced voltage on the secondary windings. We Polkies are using the transformers for an entirely different purpose, we're transferring power BOTH directions--from primary to secondary, but also from secondary to primary. Since the transformer isn't symmetrical, what works to prevent voltage loss in one direction makes the voltage loss worse in the other direction.
    Consider that any isolation transformer, even the one used with the original AI-1, will have a small difference in output when comparing primary to secondary direction and secondary to primary direction. This is unavoidable since a 1:1 isolation transformer must include a small step up function to account for transformer losses. It is unavoidable that a signal going in the secondary to primary direction will see a small step down function. However, the output differences between directions should be (and are) inaudible and should be (and are) within the range you would expect from differences in amp channels and differences in loudspeaker drivers and crossover components. The difference between the outputs of each direction will also vary with frequency. The SDA circuit operates from 1600 Hz down.


    Quote Originally Posted by Schurkey View Post
    But since I haven't actually built one, and I don't have the Electrical Engineering background (or the 'scope) to run tests, I am just making guesses that the SDA signal is compromised.
    No, the SDA signal is not compromised.


    Quote Originally Posted by Schurkey View Post
    Yes, nobody who's using one of these is complaining of SDA signal imbalance. Maybe that's good enough.
    No, no one using either a Dreadnought or the original AI-1 has complained of an SDA signal imbalance because there was none.

    I will make a separate thread on the topic of AI-1 transformer output ratios so that it will be easy to find.
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    Quote Originally Posted by F1nut View Post
    I don't know the AWG for the 800VA tranny, but it is also rated at 115V both and 3.48A. They are sold as 1:1 trannies.
    The Avel Lindberg Y236906 800VA isolation transformer uses 18 AWG wire in the primary and secondary. There is more wire in the secondary.
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