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Thread: Hello!

  1. #1
    Join Date: Oct 2020

    Location: Fife, UK

    Posts: 3
    I'm John.

    Default Hello!

    I am a retired university professor (nothing to to do with electronics, audio etc) enjoying picking up a soldering iron again after over forty years. My current system is a Naim DAC, and NAC/NAM 152 going in to a pair of Beauhorns with Lowther drivers in a very large listening space (about 10m x4m x 8m). That creates a slightly toppy sound as there is a lot more glass and walls than soft furnishing, and a bare wooden floor, but I'm not complaining. I listen to all sorts - mostly classical, especially opera, but also folk, rock, jazz... anything.
    I enjoy picking up old audio stuff at auctions and repairing/reconditioning it. I recently managed to get hold of two pairs of Quad 57s, both 1969/70 vintage. I wasn't expecting much as they came without leads, only one pair still had legs and even then only five of them. However they were both covered in so much dust that I hoped they might still be OK. I lucked out. After a thorough clean they looked fine, no arcing damage and dust covers all in one piece. They were a wee bit quiet but the volts on the EHT blocks didn't look too bad. I've since rebuilt the rectifier boards, which has pepped them up a bit. Running them as a stacked pair definitely improves them. I think my space is just too big for a single pair to be comfortable. However, even in my large space there is not enough room for the both the Beauhorns (about 1.4m x.4m x .9m) and stacked quads, so the latter are going to hang from the ceiling.
    I know positioning is going to be critical, so I want to be able to move them around (at least until I know exactly where they are going to go). That means keeping the weight down. I've replaced the front and rear grills with a lighter and sonically more transparent but still electrically grounded mesh. By far the heaviest components are the four audio transformers. I fancy moving them to the wall nearest where the speakers will hang. However I wonder about the impact of having bass panel bias voltages of 6K, along with treble panel voltages of one quarter of that, travelling for about a metre. My school physics tells me it shouldn't be a problem as long as I use high voltage cable of the kind used for test probes. But will longer cable lengths mess anything else up, such as the crossover or relative volume of the panels?
    Any advice very gratefully received.

  2. #2
    Join Date: Apr 2012

    Location: Southall, West London

    Posts: 46,359
    I'm Geoff.

    Default

    Hello John. Welcome to AOS.

    Your Quad ESL questions might get an appropriate response if placed in our Past Masters section. I'm sure members will have opinions.

    Join in the chat, there's a lot going on and it's a friendly place.


    Enjoy the forum,
    Geoff.
    Repeat after me 'I must not look on ebay! I must not look on ebay! I must not look on ebay! I must not look on ebay!

  3. #3
    Join Date: Oct 2020

    Location: Fife, UK

    Posts: 3
    I'm John.

    Default

    Thanks Geoff.
    J

  4. #4
    Join Date: Feb 2013

    Location: W Lothian

    Posts: 78,150
    I'm Grant.

    Default

    hi john, welcome to the site.. an interesting idea the tx's being taken out. if done right the ht voltages should be ok, but unless anyone has tried it, then its suck it and see.
    Regards,
    Grant .... ؠ ......Don't be such a big girl's blouse

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  5. #5
    Join Date: Sep 2009

    Location: Derbyshire

    Posts: 8,891
    I'm Josie.

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    Welcome to AOS, John.

    Hope you enjoy the forum.
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  6. #6
    Join Date: Jan 2009

    Location: Essex

    Posts: 24,870
    I'm openingabottleofwine.

    Default

    Welcome to AoS John,

    Ummm stacked Quads! I wish I had room for a set. Well done!

    The crossover frequencies are largely determined by the capacitance of panels and the inductance of the audio transformer windings, so the resistance of the wiring ought not to have much effect.

    On a point of safety, the audio voltages applied to the stators present a greater risk of shock than the HT voltage applied to the diaphragms, because the audio transformers are fed by the power amplifier which can supply high currents. So even though you might use slicone rubber insulated HT cabling, all connections to the secondary side of the audio transformers need to be very well insulated, covered and safe from curious children and pets.

    Good luck with the project.
    Barry

  7. #7
    Join Date: Oct 2020

    Location: Fife, UK

    Posts: 3
    I'm John.

    Default

    Thanks for that Barry. The plan is only to offload them till I've got the positioning sorted out, and then put them back in their usual place once I have a permanent mount for the quads. My guess is that without the weight of the transformers, the frames would move too much, and it would probably weaken the bass response. If it doesn't, or I decide to keep them off for another reason, then I'd allow plenty of safety margin for the cable insulation etc.
    If I get inspired enough I might even try working out how to alter the ratio of bass to treble panels, since the latter are plenty powerful enough for the space. However I don't see an easy way of doing that without upsetting the crossover function.
    John

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