New (old and busted) bass bins

laatsch55

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#41
Amen Davis, we've been headed that way a long time. Having an engineer of Joe's caliber hangin and rattling with us is a definate plus...he derinately keeps us on the fruitful line.
 
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#42
With two phases feeding two sets of windings, is there any fear of issues with each being on opposed phase of the A/C?
J!m, your thought process is valid, and it could be a valid concern, especially when we start cross-connecting (2) different 220v amps with 2 different AC feeds to a common pre-amp running off of 110v. (We can stop worrying at the preamp, assuming that all the music source boxes are being fed from a common power strip.)

Back when I looked into all this, I learned that on a given residential street, only (1) of the (3) phases coming from the power plant is being distributed. (And for load-balancing, the next street over has the 2nd phase, and the third street has the third phase, and this repeats...)

Anyway, at the transformer out on the pole feeding your house, it takes this single phase, and by running it through a center-tapped transformer, our house is fed with (2) equal-yet-opposite 'opposing 110v' 60hz sine wave power. (Apologies to those that already know all this - just trying to illustrate the point. Anyway, if you trace out the power flow inside your circuit-breaker panel, you will see these (2) separate 110v feeds are physically alternated. Ergo, a single breaker = 110v -- double breaker = 220v.)

OK, given this I *think* that depending upon where you have your 220v circuit breaker physically located (ie: left vs. right stack in your breaker box) you could end up where if you were to scope/trigger the 'A' channel on the 'hot' wire feeding the LEFT amp you would see the power peak positive, while simultaneously if you were to put the 'B' channel of the scope on the RIGHT amp you would end up with the 'hot' wire showing the peak negative at the same moment in time. (And the 110v line level boxes would be in a 'power phase sync' with one amp or the other, but not both.

****

The solution would be to avoid putting your system into that kind of power quandry. If it was my listening room, I would first figure out where do I physically locate the (2) 220v circuit breakers so that they are 'in phase' with each other. This would be easy to verify using a 2-channel o-scope.
Voila! And then for bonus points you could try the 110v circuit breaker on each leg & go with whichever brings your system the most tranquil baseline.

****

I don't know if I did justice to all of the above...and please, any electrician out there who can make this a better explanation don't hesitate to accuratize my attempted description. (I *do* know that one time I went through all my 2-prong boxes and (those that had identical-width non-polarized plugs) I would flip one power connector both ways, measuring the 2 resulting voltage differentials between the 2 box chassis under test, and went with the lowest reading between the 2. (And then marked each plug with a red nail polish dot so that I could keep it right after unplugging/replugging stuff. (And yes, I could hear the difference in lower background hum in the overall system. (!)

****

Getting back to your question -- 1) Your concern is valid, but 2) we should be able to get both amps fed power 'in phase', and 3) we can prove it with a dual-trace scope.

Does this makes it clearer, or further muddy the waters?

FWIW -
 
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#43
Amen Davis, we've been headed that way a long time. Having an engineer of Joe's caliber hangin and rattling with us is a definate plus...he derinately keeps us on the fruitful line.
Agreed! And it really shows -- although I'm a pretty happy-go-lucky dude (especially for an 'audiophile' :0) ...I am really serious about making the very most out of what I've got to listen to. So the fact that I decided to make my last stand here is the proof in the pudding, so to speak.

You'll have to excuse me. I have a *lot* more reading ahead of me before I have a real clue about the lay of the land here.

But already you guys have exceeded expectations. It's like finding the one All-U-Can-Eat Chinese Buffet where the food is really good...and affordable! (ie: Bulk Cuisine, my highest rating! :0)
 

laatsch55

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#45
It's not like you are trying to balance the load in a 100 floor skyscraper!! To get 240 out of the house just as Davis described, alternate 120 breakers..
To get 240 out of those dual primary toroids it's a series connection, so a phase problem really isn't going to manifest itself on the DC side..

Now......if you are not using the 3rd grounding lug, as in some of our old gear, then that could be a concern..
 

J!m

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#46
I have a plan to pull a 20-amp breaker off the top of the box (first leg this side of the main) and run that with an isolated ground for stereo feeding.

Maybe I should plan on two…. Is 2400 watts enough for a pair of class-A amps running 100 watts output (into 8 ohms)?
 

J!m

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#48
I’m going to need Sniff’s thong for mid-winter listening.

Maybe I can bake bread in the warmer months. I had an easy-bake oven, so I have the requisite culinary skills to cook in a room heated to 450 degrees.

But seriously, maybe I go the Krell route with fan cooling. Then I can run a dryer duct outside with most of the heat…
 
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#49
I have a plan to pull a 20-amp breaker off the top of the box (first leg this side of the main) and run that with an isolated ground for stereo feeding.

Maybe I should plan on two…. Is 2400 watts enough for a pair of class-A amps running 100 watts output (into 8 ohms)?
It's all about the duty cycle --

J!m, it's a funny thing. ( 2400w <> 100w ) Sounds like potential overkill, especially to those who think that we get to work with all 360 degrees of the 60hz power sine wave. (ie: a 100% duty cycle) But we don't -- our power supplies don't pull any current until the sine wave entering the full-wave bridge goes above the + rail (and below the - rail) where our DC rails have *currently sagged to* as a result of music signal (actually speaker amp draw) demand.

(Of course you have to factor in the turns ratio of your power transformer in order to really figure out the exact voltage where we start drawing current and/or figure out the Duty Cycle our power supply is operating at.)

In other words, given the above we only get to recharge our cap bank for a relatively small percentage of degrees only at the very top (and bottom) of each 360 degree sine wave. Given this relatively small duty cycle, the less we sag what little we have to work with, the better we stand a chance of staying ahead of demand. Because the lower the DC rails sag, the sooner audible clipping sets in. Doesn't seem fair, does it?

Tell you what -- the first afternoon I watched the DC rails bounce in that Sansui 9090 (actually considered a desirable receiver as evidenced by today's prices) in time to the music, it completely changed my perspective on what our power supplies are up against. (!)

Seriously, so many people way oversimplify the demand that we put on the internals of our amplifiers in the real world. It's one thing to scope around inside an amp when you run a 1 Khz steady-state sine wave into your amp & it's driving a purely resistive dummy load. No doubt it will probably look all cool & copasetic. But take that same amp, hook up the speakers that you are going to drive, and then play that Also Sprach Zarathustra organ recital, and really quickly the DC rails start to dance around.

Think about it this way -- when that organist has his foot mashed against the bass pedal at a 100% duty cycle for several seconds (In order to get that glorious bass reverb going in that huge cathedral listening space) ...meanwhile, the AC/DC power supply is trying frantically to stay ahead of that deep bass amperage demand with only a small percentage of the incoming sine wave available... you & I are not worried about 'average' wattage, we are trying to keep up with a steady suckage with flash-like recharging opportunities.

Amplifiying signals is one thing. Taking those amplified voltage signals and then turning them into actual WORK (via Amperage) directed towards voice coils driving mechanical transducers ... that's where the magic is.

All of a sudden 2400 < > 100 doesn't seem so ridiculous. At least not to me.

Hope that made it a bit clearer...instead of muddyier.

Cheers!
 
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J!m

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#50
I'm good.

This is why, for a simple design, Class-A appeals to me. We have Hoover dam on tap, and various exit pipes on the dry side. The more I open, the more I get, because of my massive reserve. KISS principle.

When I have to go from zero to HOLY $#!+ in a nano-second is where things get dicey with an A-B design and, seriously lousy with a digital amp providing "power on demand". I don't care the max output power is 1200 watts, and it will fit inside my toaster-oven. IT CAN'T HANG with the big dogs.

My A-B amp (Counterpoint) sounds SO much better now, not because of the wattage number increase, but because I don't get out of class-A much at all, even dealing with bass drum (where I noticed the improvement first) and just sheer volume of volume. (lots of loud stuff). With stupid power in reserve, there is no effort on the part of the amp- no mode change, no effort. Opening the 1" pipe on Hoover makes exactly no measurable change on the wet side. Open the 4" pipe for the same. Maybe a 4' pipe would be noticed? Probably not.

BUT, the balance must be struck between 480/3-phase 100kW 100% duty cycle welding power supply and audible audio reproduction. Somewhere in that range is the sweet spot...
 

grapplesaw

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#53
I bought these before Christmas
They sit in a FedEx warehouse 15 mile from my drop ship since 24 th.

many other FedEx deliveries at home that are not being delivered. Covid anyone?
 
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#54
Glenn,

In this (older) article FedEx is blaming 'lack of workers' for stuff sitting in their warehouses. Also medical & other perishables are taking precedence over stuff like we tinker with.

Personally, a couple of (new) items that I've been contemplating adding to the lab I'm brewing up...are simply not shipping at any price due to supply chain-related parts shortages?

It's been a long time since I read 'Atlas Shrugged'. From the way things are going maybe I should read it again...
 

grapplesaw

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#56
This project may be redesigned
one of the speakers was returned to FedEx for inspection. Find out Monday what that means. The other is still in Oregon. Ugh!,
 
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