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Destroyer x Amplifier...Dx amp...my amplifier
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Old 27th April 2007, 11:29 AM   #1041
richie00boy is offline richie00boy  United Kingdom
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Destroyer x Amplifier...Dx amp...my amplifier
Thanks Greg, that's cleared everything up now.
www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, modules and more.
Old 27th April 2007, 02:08 PM   #1042
BillH is offline BillH  United States
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Thanks to all for the help with the spade terminals. They're shown on Mouser's page 1217.

Hi Carlos, thanks for the parts substitutions and I'll get the dimensions you asked for when I get home tonight.

The transformer may be the limiting factor. It had 1.6A fuses on the + and - DC rails. When it was operating in the receiver, it was putting out + and - 42 vdc at idle. Feel free to correct my maths, Mr. Ohm's law of P=I^2*R gives me 1.6^2*8 or about 20 watts into 8 ohms just before the fuses blow.
Old 27th April 2007, 02:35 PM   #1043
kvholio is offline kvholio  Netherlands
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BillH, the formula you use would apply to a speaker-protection fuse, assuming a constant signal at the output of the amplifier and an 8 ohms resistive load.

Assuming a 10% voltage-drop of the transformer at full power, the maximum continuous power the transformer delivers at the amplifier-circuit is 1.6 * 38 * 2 = 121,6 watts before blowing fuses.

But in practice you don't play continuous sinewaves, also those fuses will not blow at 1.61 A current-draw
It gives you a ballpark-value of the va-rating of the transformer imo.

Best regards,

Old 27th April 2007, 02:59 PM   #1044
destroyer X is offline destroyer X  Brazil
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Default The Dx amplifier will need around 2.3A to each rail...and for a single channel

Also considering losses...your DC supply will go down to 36 volts.

Under that condition, the supply fuses, feeding only one channel, had to be 2.5A each rail

Using a single supply for 2 Dx amplifiers, the rail fuses installed into the supply output, had to be 5A each one of them.

Your supply will be enougth to only a channel.

Better to find another second transformer, as this one will be enougth to a single channel...and even for a single channel it will be not perfect.



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Thanks Klaas...i had a little different numbers, but your idea is fine too....mine was a little more abusive to the transformer.

BillH has transformer, and also output transistors, and those parts will fit only one channel.

And this makes sense to fast evaluation..Dx amplifier will produce twice the power...so.... that small transformer will hold a half of Dx amplifier.....so....not a stereo..only a single board.


Old 28th April 2007, 05:08 AM   #1045
BillH is offline BillH  United States
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Here are some heat sink and transformer dimensions. The metric dimensions [mm] are in brackets with inches below. It has been a long day, I need some sleep. I'll be able to think better tomorrow.
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Old 28th April 2007, 05:28 AM   #1046
PhongVuTuan is offline PhongVuTuan  Viet Nam
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Default Re. amp amp

Yep, DestroyerX, I have seen your post criticizing my amp. In this instance you are right. But my amp didn't get burned like amazon forest but it distort at high volume. I'm going around in search of a scheme to provide more base current for my exhausting outputs.
Old 28th April 2007, 08:27 AM   #1047
destroyer X is offline destroyer X  Brazil
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Default Yes Bill, they seems to be 200 watts components...not only the transformer, but also

the heatsink..... They will be enougth of one channel only...of course you can reduce your volume...but this will be hard to control all time long.

The heatsink, using a good fan, will work fine dissipating the heat of both channels i think....but even this way, your power transistor junctions may melt, as heat transference may not be fast enougth...the outside cooling may not help.

That 80W of each transistor is under 25 degrées centigrades...and that temperature, to be stable, is very difficult to control outside a laboratory that use cooling gazes and infinite metal blocks.

A very nice sketch....the image you draw Bill,...please, inform the program you have used to produce that nice image.



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Dear Phung

It is normal that amplifiers, the ones has not protection to distort, to scream alike a crazy pig when over driven.

You may need a lot of power, not to force your unit into maximum clipping levels...as to perceive some increasing in power you need to double....to be clear the human perception of volume increasings, will be needed to multiply your power by four.

A good idea is to create more efficiency...more speakers, serial and parallel arrangements to increase sonic air pressure...more are of compressing air will result in more sound (more diafragm, speaker cone area).

Another good idea is to create a reflective wall around...as open air sound works need much more power than an inside walls system...because of reflections.

100 speakers, each one receiving 1 watt each one is many times better than a 100 watts speaker receiving 100 watts.

Also you can use horns...into bass speakers, and into mids and high frequency drivers...using acoustic amplification.

The exponential front grille is excelent for this purpose...in the speaker forum you will have many options.

In your sittuation, your needs, high power levels without distort, you may need something alike Linx amplifier... search for Delta Audio....Jan Dupont or even Jens Rasmussem may suggest you a high power amplifier enougth to your needs.

I have in my imaginations that an amplifier using 120 volts plus and 120 volts minus supply..... 16 to 20 amperes going to each channel may be reasonable for you.... i do not know if this is possible in your country.....no problems here, to find those units...from 220 to 120 Volts AC to industrial step down purposes...those ones, with a Variac in the primary is used into very high power needs.

I am not too much experienced with high power, as my needs do not go over 10 RMS clean watts each channel...normally my listening level is under 1 Watt.

The Symassym you are searching will not be enougth.... even Linx will need modifications to your use, as you may need 1 Kw or more, to play loud 400 or 500 watts RMS without distortion.

For sure, a cheap amplifier, a simple amplifier, will not match your superior power needs.... to you needs, Dx amplifier may be one of the worst options to use.

We are trying to keep our Amazon untouched, but there are many International interests there...people are burning there alike other countries have already made.... they were not perfect...we are not perfect too.

There are many Non Government Institutions working there to "save" the forest...in reality they are providing exportations of wood, some animals and plants to outside country.

I believe you have enormous jungle too....maybe your place will be more controled, as your people have shown us how decided you are.


Old 28th April 2007, 10:32 AM   #1048
Graham Maynard is offline Graham Maynard  United Kingdom
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Hi Carlos,

Two of your amplifiers with extra output devices could be bridge connected.
Say 2x 250W to give a 500W chassis, this with 70Vrms line output capable of driving very many line loudspeakers in a large building.

Cheers ......... Graham.
Old 28th April 2007, 11:01 AM   #1049
Nordic is offline Nordic  South Africa
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bought 10R 10W resistors and crocodile clips... off for eyetest now... but the weekend is still long.
Old 28th April 2007, 11:04 AM   #1050
destroyer X is offline destroyer X  Brazil
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Default Yes..... will be interesting, the Thunderstorm X

Inspired into the crazy scientist.... already passed...dead, Ludwig Von Melter.

Do you want to make this one dear Graham?

To adapt Dx amplifier in such a way?

Your cooperation will be received as a party here.

The new monster, the melter...Thunderstorm X..the voice coils assassine... it is serious..wanna make it Graham?.... to 1 ohm voice coil..hehe...nice that!

Phong will burn Hanoi city wires and transformers.

I have made a simulation, and 2 Kw was not difficult over 2 ohms...a lot of transistors, bridged and enormous power transformers.




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