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Old 12th June 2012, 01:11 PM   #1
Markgm is offline Markgm  United States
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Default What happens with a higher voltage than needed?

Hi,
I'll have to ask y'all amazing electronics brains. If I have a tk2050-based amp that needs an outboard PSU and I am wondering how much I can get out of it.

I believe that going past 4.1 amps/channel won't go... Please let me know if this is not the case.

If it is the case, then let's say I have a 4 ohm load (per channel). It seems that at around 16.4 volts, 4.1 amps, 4 ohms, 64 wpc, that 16.4 volts is as much as it can use. So the question is, what do I get from using a (current-capable) 20-volt PSU? Or a 30 volt PSU, with this load? Would I be able to get more out of it?

Cheers,
Mark
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Old 12th June 2012, 01:34 PM   #2
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Quote:
Originally Posted by Markgm View Post
Would I be able to get more out of it?
More what, smoke?

So I assume your questions are for a 4-ohm load on a single channel and not two channels in parallel?
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Old 12th June 2012, 01:44 PM   #3
Markgm is offline Markgm  United States
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Per channel - two channels - two speakers. I was under the impression that I could not get more than 4.1 amps per channel in a 2-channel setup from this ...
Virtue Two.2 tk2050-based amp

Such as from at least an 8.2 amp-capable PSU. Is the amplifier output voltage just going to go as high as it can go - for the load, drawing from input voltage?

Would a 4-ohm load (per channel - 2 channels) do best running the amp at around 16 volts? Would a 6-ohm load do best running the amp at around 24 volts? Would an 8-ohm load do best when running at around 30-32 volts?

Would 30+ volts be the best voltage for a PSU for any speaker impedance?

Cheers,
Mark

Last edited by Markgm; 12th June 2012 at 01:47 PM.
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Old 12th June 2012, 02:11 PM   #4
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So you have a Virtue Two.2?

Where are you getting this 4.1A number from?
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Old 12th June 2012, 03:19 PM   #5
Markgm is offline Markgm  United States
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Quote:
Originally Posted by theAnonymous1 View Post
So you have a Virtue Two.2?

Where are you getting this 4.1A number from?
This is jogging my memory, because I don't exactly recall. Sorry. I just spoke with a fellow at Virtue who says these amplifiers "cannot pass through more than 6 amps".
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Old 12th June 2012, 03:58 PM   #6
AndrewT is online now AndrewT  Scotland
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The TK2050 datasheet should tell you all these answers.
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Old 12th June 2012, 04:03 PM   #7
sreten is offline sreten  United Kingdom
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Hi,

If you have a higher PSU voltage than actually needed you gain a little in peak
unclipped output and lose something in continuous power output, depending
on the way the SOA protection and current limiting of the amplifier works.

Running an amplifier at recommended maximum voltage for 8 ohms can be
done into 4 ohms, but its simply not as reliable (depending on the protection),
as it forces the output stage to dissipate more heat than the 4 ohm voltage.

Any 8 ohm amplifier can produce enough current for 4 ohms up to -3dB
output level. If the current limiting is at a fixed level, not dynamic, there
is no advantage to using a higher voltage than necessary into 4 ohms.

Its really about does the amplifier voltage clip or current limit first ?

rgds, sreten.
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Old 12th June 2012, 04:53 PM   #8
Markgm is offline Markgm  United States
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Here is the datasheet.

I believe the Two.2 runs in dual full bridge mode.

From page 3:
ISC Short-circuit current limit VCC = +30V, T=25oC
min: 3.5
typical: 5
max: 6.5 A

I just got a correction - was not 6 amps total but around 6 amps per channel.

OK, so one other thing... WIth a little testing, I think I liked the sound with 5 ohm speakers at around 27-8 volts supply, and another fellow tells me he likes around 28 volts as a "sweet spot". Possibly?

Thanks, sreten. I was wondering if too much input voltage could ultimately subtract from how much current I could get on the output side. Any guesses on how significant it would be to switch from a 30 volt supply to (for example) a 20 volt supply with 4 ohm speakers?

Cheers,
Mark

Last edited by Markgm; 12th June 2012 at 04:59 PM.
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Old 12th June 2012, 05:54 PM   #9
Markgm is offline Markgm  United States
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Adjusting for the new (actual) current capabilities, it seems like for a 4 ohm load, maybe 26-28 volts would be fine, with current limiting at around 5.5-6 amps. So I guess I don't see any advantage to input voltage lower than that.
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Old 12th June 2012, 06:25 PM   #10
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The thing I was trying to figure out before was if the amp had two TP2050 (one for each channel) in parallel output configuration or just one, limiting how much current it could flow into a 4-ohm load. It looks like the amp has two, so there is no reason to not use a 30V supply.
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