Odd Block Series 1 6L6 Amp Power Supply

kawasaki99 · 16th December 2010, 06:09 AM

Currently building 6L6GC PP amp using the Odd Watt schematic posted by Oddwatt Audio( 6/24/2009 ). The power supply transformer I'm using is rated 5 amps @6.5v ac. Using the bridge ,diodes and cap as specified, the dc output for the heaters drops to 4.1 volts when loaded. Is it typical for the ac to dc conversion components to drop that much voltage? Any suggestions to get the voltage back up to 6.3v would be appreciated. I'm very new to the vacuum tube hobby.
Regards, Richard

azazello · 07:34 AM

There is drop on bridge rectifier, I'm afraid that You can't use DC heating with this transformer with secondary 6.3 v.Try heat tubes without bridge rectifier. If You use 6L6, 5A from Transf. are small
for all tubes. You can try schematic with 6BQ5, 6AQ5/6005/, 6V6....with resistor 12-13 ohm/2 watts on each LM317.

kawasaki99 · 17th December 2010, 04:29 PM

Hello,
Thanks for the prompt reply regarding the 6L6 amp. I tested the power supply and discovered a 2.2 volt drop across the three heater diodes. By removing them from the circuit the heater voltage is raised to 6.0 volts dc but of course adding about 1 volt of ac ripple. First, are there more efficient diodes available then what is called for in the schematic and secondly is using the power supply with the diodes removed a bad idea?
Regards, Richard

artosalo · 17th December 2010, 05:02 PM

Are you supplying 6L6GCs with DC too ?
It is fully un-necessary. Give them AC and then to rest of tubes DC.
Then the voltage drop is much less.

kawasaki99 · 17th December 2010, 06:17 PM

Hello,
If using ac for the 6L6 tubes is the dc heater bias circuit necessary. and will it function with ac heaters? There is a strong warning on the schematic to use the heater dc bias circuit to prevent smoke and fire.

Regards, Richard

16th December 2010, 06:09 AM	#1
kawasaki99 diyAudio Member Join Date: Nov 2010	Odd Block Series 1 6L6 Amp Power Supply Currently building 6L6GC PP amp using the Odd Watt schematic posted by Oddwatt Audio( 6/24/2009 ). The power supply transformer I'm using is rated 5 amps @6.5v ac. Using the bridge ,diodes and cap as specified, the dc output for the heaters drops to 4.1 volts when loaded. Is it typical for the ac to dc conversion components to drop that much voltage? Any suggestions to get the voltage back up to 6.3v would be appreciated. I'm very new to the vacuum tube hobby. Regards, Richard

16th December 2010, 07:21 AM	#2
azazello diyAudio Member Join Date: Aug 2008 Location: Bulgaria	There is drop on bridge rectifier, I'm afraid that You can't use DC heating with this transformer with secondary 6.3 v.Try heat tubes without bridge rectifier. If You use 6L6, 5A from Transf. are small for all tubes. You can try schematic with 6BQ5, 6AQ5/6005/, 6V6....with resistor 12-13 ohm/2 watts on each LM317. Last edited by azazello; 16th December 2010 at 07:34 AM.

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
Power Supply Voltage For 5881/6L6 Amp	simonmurr	Tubes / Valves	2	1st December 2009 05:16 PM
Profile A1200 XL Odd Power Supply	amc32	Car Audio	5	26th November 2008 10:44 PM
questions about power supply for 6l6 pp	dionisio	Tubes / Valves	18	10th March 2005 02:14 PM
Power supply for a active summing block.	S.C	Car Audio	19	14th June 2004 10:56 PM

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

17th December 2010, 04:29 PM	#3
kawasaki99 diyAudio Member Join Date: Nov 2010	Hello, Thanks for the prompt reply regarding the 6L6 amp. I tested the power supply and discovered a 2.2 volt drop across the three heater diodes. By removing them from the circuit the heater voltage is raised to 6.0 volts dc but of course adding about 1 volt of ac ripple. First, are there more efficient diodes available then what is called for in the schematic and secondly is using the power supply with the diodes removed a bad idea? Regards, Richard

17th December 2010, 05:02 PM	#4
artosalo diyAudio Member Join Date: Feb 2010	Are you supplying 6L6GCs with DC too ? It is fully un-necessary. Give them AC and then to rest of tubes DC. Then the voltage drop is much less.

17th December 2010, 06:17 PM	#5
kawasaki99 diyAudio Member Join Date: Nov 2010	Hello, If using ac for the 6L6 tubes is the dc heater bias circuit necessary. and will it function with ac heaters? There is a strong warning on the schematic to use the heater dc bias circuit to prevent smoke and fire. Regards, Richard

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