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Old 18th January 2013, 07:41 PM   #8181
dvv is online now dvv  Serbia
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Actually, Nige, that may be some waystation, because in the end, the best overall solution is an active speaker.

Just imagine the bass or tweeter being connected to the driving amp by something like 10 inches of wiring of your choice, no resistors, capacitors or inductors in the way to cause nasty phase shifts and decrease natural driver efficiency, and so forth.

Under such circumstances, I believe some of the available all-in-one-chip power amplifiers would do just fine, possibly even very well. After all, they'd be seeing as clean and easy load as possible.

Assuming you select your power amp chip well, and are not stingy about it, and with no passive crossover losses, you might be able to get some awesome dynamics in a room.

Not to even mention the Games Unlimited you get at no extra charge. For example, if you have a say 96 dB/2.83V/1m efficient tweeters, which are powered by a say 50 WRMS chip power amp, you could easily add a series resistor and not have to worry about drive power.

Or, if your really went for it, you might consider the opposite direction, such as putting two tweeters in parallel, because again, practically nothing stands in the way between them and power amp driving them.

MOST interesting thoughts become possible.

The only caveat that comes to mind is the problem of cables linking the active speakers and the command center, the preamp. Personally, I'd think hard about balanced lines, but obviously only after first deciding where to place the electronic crossover. If placed inside the speaker, then it would also act as a buffer for the chip power amps.
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Old 18th January 2013, 07:52 PM   #8182
DF96 is offline DF96  England
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Quote:
Originally Posted by a.wayne
Why higher voltage vs VA ..?

How can a 50v 500va transformer make an amp sound better than an 40v /800va one , i don't get this , big transformer big cap bank , yes ..

The larger VA oversized transformer will have less noise for sure .....
Unless you listen to continuous sine waves, or many modern CDs with almost no dynamic range, the transformer has plenty of time to recharge the caps during the quieter periods. The higher the voltage they recharge to (set by the secondary voltage, not VA - within reason) the more you can droop when the next music peak comes along.

As I said, it is counterintuitive so some people will find it hard to believe. Do the maths, or read the other thread and believe the maths we have done. The right transformer can be better than the bigger transformer. I guess I am arguing for design, not fashion following.

Of course, if you have to sell a product then you may need to degrade its performance by putting in a bigger transformer which can supply more current than necessary in preference to one with a bigger secondary voltage which can provide more headroom.
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Old 18th January 2013, 07:54 PM   #8183
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What you are talking about, gentlemen?

What capacitance? What Joulies?

Suppose, I have an amp. It draws 1 A constantly, it has a source follower output supplied by current source. Let's take the worst scenario: output resistance of the source follower is 1 Ohm, dynamic resistance of current source is 1 KOhm only. That means ripples and sag from power supply re 60 db down on speaker terminals. So if they are huge, like 1 Volt, there will be -80 dB S/N level on speaker terminals caused by PS ripple and sag. Now let's calculate which minimal capacitance do I need for -80 dB or below?

It's the practical question based on strong arithmetic theory. No esoteric at all.
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Old 18th January 2013, 10:24 PM   #8184
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Quote:
Originally Posted by DF96 View Post
Unless you listen to continuous sine waves, or many modern CDs with almost no dynamic range, the transformer has plenty of time to recharge the caps during the quieter periods. The higher the voltage they recharge to (set by the secondary voltage, not VA - within reason) the more you can droop when the next music peak comes along.
This is the Krell "secret" of course - what they did was realise that minimising voltage droop was the name of the game, and they threw a lot of resources and money at refining that. Hence the infamous Krell bass, simply because the power supply didn't collapse when some meaty notes needed to be played.

That the rest of the amp wasn't too sharp at reproducing everything else probably didn't worry them too much ...

Frank
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Old 18th January 2013, 10:34 PM   #8185
a.wayne is offline a.wayne  United States
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Originally Posted by fas42 View Post
This is the Krell "secret" of course - what they did was realise that minimising voltage droop was the name of the game, and they threw a lot of resources and money at refining that. Hence the infamous Krell bass, simply because the power supply didn't collapse when some meaty notes needed to be played.

That the rest of the amp wasn't too sharp at reproducing everything else probably didn't worry them too much ...

Frank
Infamous bass .....

I'm wagering you have not heard much Krells, if using them on an 8 ohm speaker load, then its a waste , put them on Maggies, apogees, or anything with a 4 ohm impedance or lower and they shine thru. While not the best sonically, they were easily top tier of the day ...
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Old 18th January 2013, 10:57 PM   #8186
fas42 is offline fas42  Australia
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Originally Posted by a.wayne View Post
Infamous bass .....

I'm wagering you have not heard much Krells, if using them on an 8 ohm speaker load, then its a waste , put them on Maggies, apogees, or anything with a 4 ohm impedance or lower and they shine thru. While not the best sonically, they were easily top tier of the day ...
I think you misunderstood me, I just said exactly what you repeated: Krell could do brilliantly driving extremely severe loads, maintaining bass performance at high volumes.

Here, I will again put in a good word for the Australian ME amplifiers, which back then could easily out-Krell a Krell, how about 1500W into 1 ohm per channel, continuous, both channels driven. 5KVA transformer, 300,000uF, switchable class A operation. The bloke behind it had problems in the interim, but has re-emerged, at the moment with far less ambitious units: Home

Frank

Last edited by fas42; 18th January 2013 at 11:00 PM.
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Old 19th January 2013, 01:07 AM   #8187
a.wayne is offline a.wayne  United States
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ME, 1500 watts @ 1ohm ! what is ME, I will search for it , it's my destiny .....


EDIT: Do you really need a thousand little caps , I'm limited to 8 , it's a round number and in stock ...
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Old 19th January 2013, 01:44 AM   #8188
fas42 is offline fas42  Australia
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ME, 1500 watts @ 1ohm ! what is ME, I will search for it , it's my destiny .....


EDIT: Do you really need a thousand little caps , I'm limited to 8 , it's a round number and in stock ...
It's "hidden" in that last link, in my previous post! Home ... me-au.com ...
Nope, the number of caps doesn't have to be huge, though that ME used 92, I seem to recall .... It's about the right values, in the right place ... patience, Grasshopper ...

Frank
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Old 19th January 2013, 05:29 AM   #8189
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How far have we come in 25 odd years? The new, "ultra monster" Boulder 3060 only does 900W into any load, meaning I guess also 1 ohm ...

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Old 19th January 2013, 06:11 AM   #8190
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That's the one they're discussing over at 'another place' where the 17keuro premium for black is being questioned?
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