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Old 12th April 2012, 09:25 AM   #1
Shelah is offline Shelah  Zambia
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to the diyaudio community i have a toroidal transformer i got from an old powered mixer.it had no specification with it. the only things i could measure from it were as follows:
primary: 220v 50Hz, 5 amp fuse.
Secondary:
1. 60v-0-60v
2. 19v-0-19v
3.24v-0.
the transformer was used on an op-amp based Class AB amplifier rated 325W 4 ohms. on the damaged pcb, these were some readings printed.
  • 10 amp fuse before rectifier of amplifier (60v-0-60v)
  • 1 amp fuse before rectifier for mixer section (19v-0-19v)
  • the diodes of the amp rectifier: "AO8, 6amps"
  • diodes for the mixer section rectifier: "1N4007
i dont intend on repairing the amplifier section cause of the amount of voltage used. i would like to use it on a 700w leach amp i got from this link http://www.te1.com.br/2011/03/amplificador-de-660-watts-rms-4-ohms-mono/ designed with the following specs.

Total Power 660 W RMS into 4 Ohms.
Amplification class AB
Frequency Response: 20 Hz to 20 kHz, +0, -0.3 dB
THD + N (Total Harmonic Distortion + Noise: at 4ohms = <0.05% 20Hz to 1kHz, increasing linearly to 0.1% at 20kHz
IMD (Intermodulation Distortion): 90dB at 8ohms
Supply voltage: Symmetrical Amperes 63 Volts x 12
Nominated 50 +50 Trafo x12A
Load impedance: min. 2R
Speed ​​over (SR) 35V/us
Input sensitivity: about 1.1 V for full arousal

with the information given, can someone help me find out what the VA rating would be both theoretically and in the real world and if it would be suitable for the 700w leach amp.

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Old 12th April 2012, 10:09 AM   #2
DF96 is offline DF96  England
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If it was used in a 325W amp then it is unlikely to be be able to support a 700W amp, except at a reduced duty cycle.
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Old 12th April 2012, 10:19 AM   #3
Tekko is offline Tekko
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I'd say the transformer is roughly 500-600 VA. For your 700W leach amp your gonna need atleast a 1kVA transformer.
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Old 12th April 2012, 01:14 PM   #4
AndrewT is offline AndrewT  Scotland
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+-60Vdc PSU is unlikely to get any more than 50Vpk into your speaker terminals.
That predicts a maximum power output from this design @ ~312W into 4r0

Where did 660W to 700W come from.
Did you check the numbers?
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Old 13th April 2012, 09:54 AM   #5
Shelah is offline Shelah  Zambia
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@tekko thanks for your estimation. i theorectically got somthing close to that. one other thing, the leach amp specs on 320volt.com and hobbyelectronics.blogspot.com says that a 54x2 transformer was used. but how would mine not work in this case?

@Andrew T, i did check the numbers and please check the web link i gave and also 320volt.com andhobbyelectronics.blogspot.com
i also forgot to put something on the specs.
output power: 260w 8R, 450w 4R, 680w 2R.
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Old 13th April 2012, 01:53 PM   #6
AndrewT is offline AndrewT  Scotland
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Yes I looked at your linked page, yes I read some of what it said.

I'll ask again, did you check the numbers?
450W into 4r0 requires 60Vpk into your 4r0 test load. How do you get that from the details given?
260W into 8r0 requires 64.5Vpk !



it also said
Quote:
Amplificador de 660 ~ 700 Watts RMS 4 Ohms mono
Do you just accept anything you read?
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Last edited by AndrewT; 13th April 2012 at 01:58 PM.
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Old 13th April 2012, 02:03 PM   #7
TonyTecson is offline TonyTecson  Philippines
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@Shelah,

how big is this traffo? what is the weight in kgs? are you using this traffo for a 2 channel leach or just one channel?

if you can answer my question i will be able to help you...
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Old 13th April 2012, 05:30 PM   #8
Shelah is offline Shelah  Zambia
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@ Andrew, sorry sir, maybe i didnt read. am just in need of help on the same.
@tony the trafo could be about 5 to10 kilogammes, 12 to 15 centimeters in diameter, and about 7 centimeters thick.
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Old 13th April 2012, 06:24 PM   #9
VibroKing$ is offline VibroKing$  Italy
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To estimate power of toroidal transformer it can compare weight with a similar product.
Transformer Manufacturer UK - Airlink Transformers
600VA for 350Wrms + 350Wrms is suitable for domestic use, 800VA or more for professional.
also Clone with 2sc5200 x 8 = 1200W perhaps is a waste if you do not have to drive loads below 2 ohms (imho)
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Old 14th April 2012, 01:51 PM   #10
Shelah is offline Shelah  Zambia
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@Vibroking$ what do you saggest in the correct number no 2sc5200 i can use at the output for 2 ohms?
and is mine trafo for domestic or professional use with regard to the data given in my first post?
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