Sound Valves M-40 assistance

audioquestM-40 · 18th December 2005, 06:28 PM

I am looking for manual, schematic, and parts list. Anyone know where to get any or all of these?

The dual color indicator light on one of my amps is only partially functional and would like to have it repaired.

Also, what are ok to substitute for EL 34 and 6gh8 tubes?

As you can tell I am completely a rookie at tube gear.

Any and all help wil be greatly appreciated.

Eli Duttman · 18th December 2005, 08:03 PM

I can't help with the doc. or the SS parts, but I can help with the tubes.

You should use EL34s as "finals". There are 2 good varieties in production: The SED ("flying C") EL34 out of St. Petersburg, Russia and the JJ E34L out of Jamona, Slovakia.

If you can't source 6GH8s, 6U8s should be OK.

SHiFTY · 18th December 2005, 09:10 PM

You should only use those types of tubes/valves approved by the manufacturer, i.e. replace EL34s with EL34s and so on.

However the tubes may well be fine.

For good sound, use New Old Stock (NOS) tubes from the 50's and 60's. Mullard/Philips Made in Great Britain EL34s are the best you can get but big $$$.

For 6GH8 you should try all the NOS ones you can get from the different manufacturers, eg RCA, Sylvania etc. eBAY is not a bad place to start looking... be careful of scammers though!

audioquestM-40 · 20th December 2005, 05:46 PM

Thanks. Was looking for the service manual as it has a dual color LED, of whcih one color does not fire. Not sure if it's reverse polarity that activates it or what.

I've currently got Groove Tube EL34's in it, which sound pretty good, and have tried 6u8 in place of the factory 6gh8's. The 6U8 have a bit richer sound, and still provide a lot of detail. I did order a couple other American brand NOS tubes of those varieties to experiment a bit, as like I said, I'm 100% new to tube.

WAF was high so I expect tubes are in my home to stay

18th December 2005, 06:28 PM	#1
audioquestM-40 diyAudio Member Join Date: Dec 2005 Location: Canada	Sound Valves M-40 assistance I am looking for manual, schematic, and parts list. Anyone know where to get any or all of these? The dual color indicator light on one of my amps is only partially functional and would like to have it repaired. Also, what are ok to substitute for EL 34 and 6gh8 tubes? As you can tell I am completely a rookie at tube gear. Any and all help wil be greatly appreciated.

18th December 2005, 08:03 PM	#2
Eli Duttman diyAudio Member Join Date: Apr 2004 Location: Plainsboro, NJ	I can't help with the doc. or the SS parts, but I can help with the tubes. You should use EL34s as "finals". There are 2 good varieties in production: The SED ("flying C") EL34 out of St. Petersburg, Russia and the JJ E34L out of Jamona, Slovakia. If you can't source 6GH8s, 6U8s should be OK. __________________ Eli D.

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
Hafler parts - Sound Valves?	DMF	Solid State	21	24th March 2010 08:12 PM
Searching Sound Valves M40 Monoblocks schematic	echo_airiti	Tubes / Valves	2	25th January 2008 01:32 AM
sound valves m-40 schematics	11ongas	Tubes / Valves	3	10th February 2007 11:20 PM
Please Help with Sound Valves M40 Monoblock Bias Adjustment Procedure!!!	mq1688	Tubes / Valves	0	19th September 2006 09:37 AM
need assistance	mbates14	Solid State	9	5th September 2005 02:40 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

18th December 2005, 09:10 PM	#3
SHiFTY diyAudio Member Join Date: Jul 2002 Location: New Zealand	You should only use those types of tubes/valves approved by the manufacturer, i.e. replace EL34s with EL34s and so on. However the tubes may well be fine. For good sound, use New Old Stock (NOS) tubes from the 50's and 60's. Mullard/Philips Made in Great Britain EL34s are the best you can get but big $$$. For 6GH8 you should try all the NOS ones you can get from the different manufacturers, eg RCA, Sylvania etc. eBAY is not a bad place to start looking... be careful of scammers though!

20th December 2005, 05:46 PM	#4
audioquestM-40 diyAudio Member Join Date: Dec 2005 Location: Canada	Thanks. Was looking for the service manual as it has a dual color LED, of whcih one color does not fire. Not sure if it's reverse polarity that activates it or what. I've currently got Groove Tube EL34's in it, which sound pretty good, and have tried 6u8 in place of the factory 6gh8's. The 6U8 have a bit richer sound, and still provide a lot of detail. I did order a couple other American brand NOS tubes of those varieties to experiment a bit, as like I said, I'm 100% new to tube. WAF was high so I expect tubes are in my home to stay

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