High End Preamplifier

hadihf · 8th August 2008, 04:17 PM

Hi,

This seems to be stupid but I odered the wrong tranformers for the high end preamplifier project published in Elektor April/May2004. Question, would a 5VA transformer work in place of 10VA for this project?

Regards
Farooq

lineup · 8th August 2008, 09:03 PM

for a preamplifier 5 VA can be good

depends a bit on the type of amplifier
Is it Class A?
How much is the voltage. +V and -V ?

analog_sa · 8th August 2008, 10:31 PM

Quote:

Originally posted by lineup

Is it Class A?

Not quite.

It's hardly a preamp - just a PGA2311. 5VA would be pretty marginal in most cases but here probably doesn't matter much.

hadihf · 9th August 2008, 02:38 AM

There are two power supplies, one digital and on analogue. The digital is +-5V for PGA2311. The other is for the PIC, and relay board and is +5V. If I roughly divide the current consumption for the analogue one,

PIC = 10mA
LCD+Backlight = 50mA
IR sensor = 5mA
Relay board (2 Relay on) = 75 mA
misc = 60mA

It sums up = 200 mA

The analogue supply is parallel that means total current capacity@5V = 500mA. That should be sufficient. Please somebody correct me if I am wrong.

Regards
Farooq

analog_sa · 9th August 2008, 07:40 AM

You are correct and it will indeed work. Of course any preamp with "high end" pretensions is expected to have appropriately oversized power supply - something like 50VA for the PGA would probably be average.

AndrewT · 9th August 2008, 08:44 AM

500mA of DC after the capacitor input filter requires the AC rating of the transformer to be 1A.
For a 5Vdc supply you would need at least 6Vac to supply the regulators.
That comes out at a minimum of 12VA.

analog_sa · 9th August 2008, 08:59 AM

Andrew

The Elektor design uses separate transformers: one for the PGA and another for everything else. The PGA hardly draws more than 20mA. I assume Farook has repalced each of the 10VA transformers with a 5VA.

hadihf · 9th August 2008, 12:58 PM

That is correct. I am using two separate tramsformers. Attached is the datasheet. 70040 is origional, 70020 is required to be used.
Somebody constructed already constructed it? How does it sound?

Regards

Farooq

Tolu · 9th August 2008, 02:00 PM

Hi Farooq

a colleague of a german DIY forum has built that preamp and after two hours critical listening the preamp rests on top of his cupboard and gets dusty. I would eventually propose another preamp. Do you know the P88 from Rod Elliot of Australia? That is more High End!

Elektor Preamp

Nordic · 9th August 2008, 03:42 PM

P88 is ok, but not spectacular, rather try the Pedja Rogic buffer.

8th August 2008, 04:17 PM	#1
hadihf diyAudio Member Join Date: Mar 2007	High End Preamplifier Hi, This seems to be stupid but I odered the wrong tranformers for the high end preamplifier project published in Elektor April/May2004. Question, would a 5VA transformer work in place of 10VA for this project? Regards Farooq

8th August 2008, 09:03 PM	#2
lineup diyAudio Member Join Date: Dec 2005 Location: the north	for a preamplifier 5 VA can be good depends a bit on the type of amplifier Is it Class A? How much is the voltage. +V and -V ? __________________ lineup

9th August 2008, 08:44 AM	#6
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	500mA of DC after the capacitor input filter requires the AC rating of the transformer to be 1A. For a 5Vdc supply you would need at least 6Vac to supply the regulators. That comes out at a minimum of 12VA. __________________ regards Andrew T.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Wanted - High Power, High Voltage, Audio Frequency Transformer Manual.	kimbal	Tubes / Valves	4	11th May 2009 08:05 PM
I coined the phrase HIGH VIVIDITY, to differentiate our amps from High Fidelity ones	vax9000	Tubes / Valves	8	31st October 2006 01:10 AM
6BY5 High Voltage & High Current Choke Input Design P.S.	snoopyma	Tubes / Valves	7	28th June 2006 01:32 PM
high gain 2nd order high pass active filter topology	sreten	Solid State	21	23rd March 2006 01:26 AM
Is there a no/gain preamplifier schematic using high-distortion EC90?	Layberinthius	Tubes / Valves	6	10th May 2004 06:13 AM


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

9th August 2008, 02:38 AM	#4
hadihf diyAudio Member Join Date: Mar 2007	There are two power supplies, one digital and on analogue. The digital is +-5V for PGA2311. The other is for the PIC, and relay board and is +5V. If I roughly divide the current consumption for the analogue one, PIC = 10mA LCD+Backlight = 50mA IR sensor = 5mA Relay board (2 Relay on) = 75 mA misc = 60mA It sums up = 200 mA The analogue supply is parallel that means total current capacity@5V = 500mA. That should be sufficient. Please somebody correct me if I am wrong. Regards Farooq

9th August 2008, 07:40 AM	#5
analog_sa diyAudio Member Join Date: Aug 2002 Location: Sofia	You are correct and it will indeed work. Of course any preamp with "high end" pretensions is expected to have appropriately oversized power supply - something like 50VA for the PGA would probably be average.

9th August 2008, 08:59 AM	#7
analog_sa diyAudio Member Join Date: Aug 2002 Location: Sofia	Andrew The Elektor design uses separate transformers: one for the PGA and another for everything else. The PGA hardly draws more than 20mA. I assume Farook has repalced each of the 10VA transformers with a 5VA.

9th August 2008, 02:00 PM	#9
Tolu diyAudio Member Join Date: Mar 2007	Hi Farooq a colleague of a german DIY forum has built that preamp and after two hours critical listening the preamp rests on top of his cupboard and gets dusty. I would eventually propose another preamp. Do you know the P88 from Rod Elliot of Australia? That is more High End! Elektor Preamp

9th August 2008, 03:42 PM	#10
Nordic diyAudio Member Join Date: Sep 2005	P88 is ok, but not spectacular, rather try the Pedja Rogic buffer.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read