+-70V amp needed

hernanstafe · 9th March 2007, 01:21 AM

I have a +-70V transformer and i need an amp to use it, cause most amps work at about +-40. The amp has to be 100w+ and i want to use it for a subwoofer. Any ideas? I saw the zeta320 but there's no pcb and it works with 60v not 70v

GOGY-ST-HR · 9th March 2007, 02:58 AM

HAY!
What you think when you say "transformer +/-70 volts" AC,or DC voltage after bridge rectifier and capacitors,or just AC voltage direct on transformer before bridge rect. and caps!!?? Please be precise!

quasi · 9th March 2007, 02:59 AM

Are you talking about the DC voltage of a filtered power supply or are you talking about the transformer voltage. You have expressed the voltage as DC (+70 0 -70v) and in this case there are several projects around DIY that would do the job. P:rovided the transformer is power enough you will get around 200 watts into 8 ohms.

If though your talking about the transformer voltage, 70 0 70 AC then you will end up with rails of approx +95 0 -95 volts DC. In this case you could potentially get about 380 watts into 8 ohms.

Lets us know what you got and we'll go from there.

Cheers
Quasi

unclejed613 · 9th March 2007, 04:04 AM

any idea what kind of current? for an 8 ohm amp you should have a current of 10A, or 20A for a 4 ohm amp (or stereo 8 ohm).

hernanstafe · 9th March 2007, 02:51 PM

guys! thanks for your replies, i got +/-70V OFF THE RECTIFIER, not the transformer.

jaycee · 9th March 2007, 05:08 PM

Anthony Holton's AV400 amp should fit the bill.
This delivers 400W into 4 ohms, and uses MOSFET outputs. You're going to need a big heatsink though, and plenty of capacitance. Don't bother if your transformer is any less than 600VA.

Anthony sells boards for this but you can also find the schematic floating about and make your own.

XEAGLEKEEPER · 9th March 2007, 05:27 PM

ESP's P68 fits the ticket @ 500wpc
http://www.sound.westhost.com/project68.htm
I am currently building one now using a 1.0KVA toroidal and a massive heatsink

Dave

taj · 9th March 2007, 07:30 PM

I have a pair of similar sized transformers (maybe 3-4 volts higher). Will a Leach SuperAmp (double-barreled) amplifier work with a voltage of -+70-75? It specs +-85.

..Todd

taj · 9th March 2007, 08:08 PM

Here's another design which expects -+70v rails:

http://users.swing.be/edwinpaij/ampli_mosfet.htm

Anyone ever built this one? I've never heard of it before.

..Todd

GOGY-ST-HR · 10th March 2007, 06:00 AM

HAY!
Take the look on the nice Mr. Quasi works!
http://www.diyaudio.com/forums/showt...59#post1103559

Halelujah!

9th March 2007, 01:21 AM	#1
hernanstafe diyAudio Member Join Date: Feb 2007 Location: Argentina	+-70V amp needed I have a +-70V transformer and i need an amp to use it, cause most amps work at about +-40. The amp has to be 100w+ and i want to use it for a subwoofer. Any ideas? I saw the zeta320 but there's no pcb and it works with 60v not 70v

9th March 2007, 02:59 AM	#3
quasi diyAudio Member Join Date: Sep 2004 Location: Adelaide, Australia	Are you sure about the transformer ? Are you talking about the DC voltage of a filtered power supply or are you talking about the transformer voltage. You have expressed the voltage as DC (+70 0 -70v) and in this case there are several projects around DIY that would do the job. P:rovided the transformer is power enough you will get around 200 watts into 8 ohms. If though your talking about the transformer voltage, 70 0 70 AC then you will end up with rails of approx +95 0 -95 volts DC. In this case you could potentially get about 380 watts into 8 ohms. Lets us know what you got and we'll go from there. Cheers Quasi

9th March 2007, 04:04 AM	#4
unclejed613 diyAudio Member Join Date: Dec 2006	any idea what kind of current? for an 8 ohm amp you should have a current of 10A, or 20A for a 4 ohm amp (or stereo 8 ohm). __________________ Vintage Audio and Pro-Audio repair ampz(removethis)@sohonet.net spammer trap: http://www1284177414881.v-dc.net/

9th March 2007, 07:30 PM	#8
taj diyAudio Member Join Date: Feb 2005	Leach superamp? I have a pair of similar sized transformers (maybe 3-4 volts higher). Will a Leach SuperAmp (double-barreled) amplifier work with a voltage of -+70-75? It specs +-85. ..Todd

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9th March 2007, 02:58 AM	#2
GOGY-ST-HR diyAudio Member Join Date: Dec 2006	HAY! What you think when you say "transformer +/-70 volts" AC,or DC voltage after bridge rectifier and capacitors,or just AC voltage direct on transformer before bridge rect. and caps!!?? Please be precise!

9th March 2007, 02:51 PM	#5
hernanstafe diyAudio Member Join Date: Feb 2007 Location: Argentina	guys! thanks for your replies, i got +/-70V OFF THE RECTIFIER, not the transformer.

9th March 2007, 05:08 PM	#6
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	Anthony Holton's AV400 amp should fit the bill. This delivers 400W into 4 ohms, and uses MOSFET outputs. You're going to need a big heatsink though, and plenty of capacitance. Don't bother if your transformer is any less than 600VA. Anthony sells boards for this but you can also find the schematic floating about and make your own.

9th March 2007, 08:08 PM	#9
taj diyAudio Member Join Date: Feb 2005	Here's another design which expects -+70v rails: http://users.swing.be/edwinpaij/ampli_mosfet.htm Anyone ever built this one? I've never heard of it before. ..Todd

10th March 2007, 06:00 AM	#10
GOGY-ST-HR diyAudio Member Join Date: Dec 2006	HAY! Take the look on the nice Mr. Quasi works! http://www.diyaudio.com/forums/showt...59#post1103559 Halelujah!

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