GC Power Supply

Assesears · 15th June 2004, 10:29 AM

Been playing with rail voltage went from 18v to 25v and have lost all clarity, plenty bass though, top end has disappeared.

Well this is what i luv about these little amps easy to experiment, try 22v sec's next not tried a regulated supply yet.

Cheers

carlmart · 16th June 2004, 01:32 PM

Quote:

Originally posted by Assesears
Been playing with rail voltage went from 18v to 25v and have lost all clarity, plenty bass though, top end has disappeared.

Well this is what i luv about these little amps easy to experiment, try 22v sec's next not tried a regulated supply yet.

Can you explain that a littler better? 18v and 25v DC or AC? What transformers and capacity was each transformer? What chip are you using?

Keeping all things equal, there should be improvements in power and no loss of anything by that change.

Carlos

Assesears · 16th June 2004, 04:25 PM

quote:

Can you explain that a littler better? 18v and 25v DC or AC? What transformers and capacity was each transformer? What chip are you using?

Keeping all things equal, there should be improvements in power and no loss of anything by that change.

Sorry 2*18v 225va AC & 2*25v 330va AC, ok with the 25v tranny in my opinion clarity was lost, cymbals lost there edge, so i prefer 18v AC not tried 22v AC yet.
Chip LM3875TF

Ta

Vikash · 16th June 2004, 04:58 PM

4 Ohm load?

Nuuk · 17th June 2004, 08:28 AM

Yes, we really need to know all the factors involved like the type of circuit, and speaker specs.

I have done the same as you albeit with smaller VA transformers and cannot hear a difference between 27 volt and 37 volt rails!

vladimir · 17th June 2004, 12:12 PM

Does someone knows which voltage is used in the original Gaincard ?

When speaking about PS, another idea bother me:

A few months ago someone (KT ?) claimed hi opened the Gaincard PSU and hi found inside one R-core transformer and only 4 diodes (fe5d IIRC).

Gaincard constructor uses "170 VA cut-core transformer" with "+-individual coils" - IIUC this means transformer with 4 individual secondary windings.

Now I see only one manner how to connect 4 diodes with 4 windings - one diode per winding - the most basic rectifier ("only the simplest can accomodate the most complex" :-) Someone tested such a configuration ?

Assesears · 18th June 2004, 08:16 AM

8 ohm 90dB sensitivity
nigc

Ta

Nuuk · 18th June 2004, 08:26 AM

Does the clarity return if you switch back to 18 volts?

Assesears · 18th June 2004, 08:43 AM

Quote:

Originally posted by Nuuk
Does the clarity return if you switch back to 18 volts?

Yes, but waiting for a 2x22v 225va tranny to turn up, looking back through threads alot of dudes seem to go for 22vac/31vdc.

Cheers

Vikash · 18th June 2004, 09:29 AM

Are both trannies the same make? Have you got sufficient heatsinks?

15th June 2004, 10:29 AM	#1
Assesears diyAudio Member Join Date: Feb 2004 Location: Newcastle	GC Power Supply Been playing with rail voltage went from 18v to 25v and have lost all clarity, plenty bass though, top end has disappeared. Well this is what i luv about these little amps easy to experiment, try 22v sec's next not tried a regulated supply yet. Cheers

16th June 2004, 04:25 PM	#3
Assesears diyAudio Member Join Date: Feb 2004 Location: Newcastle	Re: Re: GC Power Supply quote: Can you explain that a littler better? 18v and 25v DC or AC? What transformers and capacity was each transformer? What chip are you using? Keeping all things equal, there should be improvements in power and no loss of anything by that change. Sorry 218v 225va AC & 225v 330va AC, ok with the 25v tranny in my opinion clarity was lost, cymbals lost there edge, so i prefer 18v AC not tried 22v AC yet. Chip LM3875TF Ta

16th June 2004, 04:58 PM	#4
Vikash diyAudio Moderator Emeritus Join Date: May 2003 Location: UK	4 Ohm load? __________________ "The human mind is so constituted that it colours with its own previous conceptions any new notion that presents itself for acceptance." - J. Wilhelm. (But I still think mine sounds better than yours.)

17th June 2004, 08:28 AM	#5
Nuuk diyAudio Member Join Date: Feb 2003 Location: Somerset, SW England	Yes, we really need to know all the factors involved like the type of circuit, and speaker specs. I have done the same as you albeit with smaller VA transformers and cannot hear a difference between 27 volt and 37 volt rails! __________________ The truth need not be veiled, for it veils itself from the eyes of the ignorant.

18th June 2004, 08:26 AM	#8
Nuuk diyAudio Member Join Date: Feb 2003 Location: Somerset, SW England	Does the clarity return if you switch back to 18 volts? __________________ The truth need not be veiled, for it veils itself from the eyes of the ignorant.


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17th June 2004, 12:12 PM	#6
vladimir diyAudio Member Join Date: Aug 2002 Location: luxembourg	Does someone knows which voltage is used in the original Gaincard ? When speaking about PS, another idea bother me: A few months ago someone (KT ?) claimed hi opened the Gaincard PSU and hi found inside one R-core transformer and only 4 diodes (fe5d IIRC). Gaincard constructor uses "170 VA cut-core transformer" with "+-individual coils" - IIUC this means transformer with 4 individual secondary windings. Now I see only one manner how to connect 4 diodes with 4 windings - one diode per winding - the most basic rectifier ("only the simplest can accomodate the most complex" :-) Someone tested such a configuration ?

18th June 2004, 08:16 AM	#7
Assesears diyAudio Member Join Date: Feb 2004 Location: Newcastle	8 ohm 90dB sensitivity nigc Ta

18th June 2004, 09:29 AM	#10
Vikash diyAudio Moderator Emeritus Join Date: May 2003 Location: UK	Are both trannies the same make? Have you got sufficient heatsinks? __________________ "The human mind is so constituted that it colours with its own previous conceptions any new notion that presents itself for acceptance." - J. Wilhelm. (But I still think mine sounds better than yours.)

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