Too damn heavy!

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Deke609

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on: January 16, 2021, 04:57:02 PM
Finally installed my new nano-c plate chokes in the Kaiju rebuild. I haven't tested it yet, and so not listened either -- will post about that sometime in the near future.

But it is now WAY too heavy. Each of OPTs and plate chokes is 5 kg.  So that's 20 kg right there. Plus another estimated 6 to 8 kg for the combo of Kaiju power trafo and 2 power supply chokes.  Add in the metal chassis and the two huge power supply fim caps, and we're getting close to 35 kg. So it's definitely 70+ lbs.

That would be OK if I didn't need to move it, but I like to tweak stuff. I had a bunch of experiments planned involving the grid chokes: different coupling cap sizes, w/ and w/o damping resistors across the grid chokes. Plus trying out simple resistor bias on the drivers in place of the regulated bias. That's all on hold. It's too heavy -- and will get dropped/damaged or do damage to me.  Because of how my rack is configured, it needs to go on a shelf that is 5+ ft from the floor.  I had hoped that the additional 8 or so lbs that new choke add over the weight of the previous chokes might be manageable - but it's not. Holding a 70 lb amp at head/shoulder height is a challenge but doable. But then having to extend my arms a bit and hold it out it from my body is crazy -- the resulting leverage (amp leveraged against me) is way too much. Trying to do that multiple times a day to do tests is a complete no go. Bummer.

So I need to break it into 3 separate enclosures: power supply, right channel and left channel.  Eesh.  I don't have the stomach to do all that metal work again, so I will try Send-Cut-Send that PB has used on some of his projects ... but next winter.  On the upside, I now have a compelling reason to learn some rudimentary CAD.  And a year to figure it out. 

In the meantime, there's the new BeePre with upgrades to look forward to. Lots of tweaking possibilities there.   ;D

cheers, Derek



Offline 2wo

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Reply #1 on: January 16, 2021, 06:20:18 PM
How about going monoblock? It would require another power transformer...John

John Scanlon


Deke609

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Reply #2 on: January 16, 2021, 08:58:01 PM
Thanks John. I haven't ruled that out. I'm initially leaning towards a single shared power supply b/c I like the PS that I have, but I think i's too big to duplicate: CLCLC, with two huge film caps - the last one being 1500 uF.  That said - the idea of separate power supplies does appeal.  If I were to go that route, I'd probably use separate HV and LV trafos -- and end up with two 45 lb mono amps!  And now that I've written that, I'm pretty sure that's my fate.  Hah!

cheers, Derek



Offline johnsonad

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Reply #3 on: January 17, 2021, 02:45:34 AM
Derek, I think you are attempting to compete with Jim Dowdy on size and weight of amp builds.  Just take care of your back!

Aaron Johnson


Offline Paul Birkeland

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Reply #4 on: January 17, 2021, 05:18:28 AM
Separate power supplies are more trouble than they are worth.  Monoblocks are the way to go.  At 70 lbs, chassis thickness and reinforcement become critical. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Deke609

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Reply #5 on: January 17, 2021, 07:07:57 AM
@ Aaron: I only knew the name "Dowdy" from the MQ iron by the same name so I had to look him up. Hah! by some online accounts, His Gm-70 has me beat by over 100 lbs. Albeit in three pieces. 

@PB: thanks. Monoblocks do make sense, as both you and John have pointed out. As for reinforcement, the 1/8" chassis from Landfall Systems seems to be handling the added weight for now. The iron and heavy caps are ringed around the outside edge with just the tubes toward the middle. If need be, I could add a support post or two, but any kind of angle bar running the width of the amp would require a lot of disassembly - which I am loathe to undertake. So fingers crossed that it will hold up for a year or so.

cheers and thanks, Derek



Offline EricS

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Reply #6 on: January 17, 2021, 07:30:02 AM
Project weight is an issue that I've been considering lately.  I was repairing one my big 150w Class-A monoblocks that I built over a decade ago and thinking it was getting rather heavy.  Either I need to start working out more, or I need to look at projects that are lighter weight  ;D

Eric

Haven't electrocuted myself yet...   
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