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Old 20th September 2006, 09:30 PM   #1
keps is offline keps  Philippines
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Default Tranny question

I am building my first gainclone (LM3875TF). From where I am trannies are scarse, ordering online is going to be expensive. I found one toroidal tranny from some device with the following specs:

400VAC
PRIM 2x110V
SEC1&2 2x16V/12A
SEC3 18V/1A

Manufactured by Harbuch Electronics

Can I use this as a single tranny setup for my REV3(PCB) LM3875 kit?

Not to familiar with the tranny. It has 6 primary leads (2 browns, 2 blues, 1 white and 1 pink) 6 secondary wires (red &yellow, blue & gray and green & violet)

thanks in advance.
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Old 20th September 2006, 10:14 PM   #2
AndrewT is online now AndrewT  Scotland
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Hi,
are the pink or white connected to any other wire?

16V is a bit low but still workable.

Are you on 220Vac or 230Vac or 240Vac?
The transformer output will depend on the input voltage.
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Old 20th September 2006, 10:32 PM   #3
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You can use the 16 V taps. This gives a bit less V than optimum (which i figure is 18V), but it will not have any trouble driving low impedance loads.

You will get 20-25 W into 8 ohms.

dave
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Old 22nd September 2006, 11:19 AM   #4
keps is offline keps  Philippines
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Quote:
Originally posted by AndrewT
Hi,
are the pink or white connected to any other wire?

16V is a bit low but still workable.

Are you on 220Vac or 230Vac or 240Vac?
The transformer output will depend on the input voltage.
the pink ang white is not connected to anything, I actually figured it out. I use 230V with blue and brown, and that gave me the 16V output from both red & yellow, blue and gray.

Now another question is, should I connect one secondary pair to both PSU boards in parallel in AC1 and the other pair to AC2?

cheers
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Old 22nd September 2006, 11:19 AM   #5
keps is offline keps  Philippines
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Quote:
Originally posted by planet10
You can use the 16 V taps. This gives a bit less V than optimum (which i figure is 18V), but it will not have any trouble driving low impedance loads.

You will get 20-25 W into 8 ohms.

dave
Dave,

What would be the significant effect of a low voltage such as my tranny to the overall sound?

Would it clip in high volume levels?

thanks
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Old 22nd September 2006, 11:31 AM   #6
djQUAN is offline djQUAN  Philippines
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Quote:
Would it clip in high volume levels?

yep.
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Old 22nd September 2006, 11:56 AM   #7
AndrewT is online now AndrewT  Scotland
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Hi,
with a lower voltage from the PSU there is less Vpk available to drive the load. i.e. it clips a bit earlier.

But the bigger advantage is that due to less heat build up from the lower voltage rails, the chip amp can more successfully drive lower impedance and higher reactance loads.
This may well give better sound quality with difficult speaker loads.
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Old 22nd September 2006, 12:47 PM   #8
keps is offline keps  Philippines
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If I will be lucky enough, I'll get ta tranny at around 20-22 VAC.

Thanks you all guys!
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Old 23rd September 2006, 11:56 PM   #9
Stuey is offline Stuey  Australia
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Keps, Harbuch are an Australian manufacturer of quality transformers who make Antrim designs under licence.
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