ecl82 or ecl86 amplifier decision

neazoi · 16th June 2010, 10:40 AM

Hello, I am thinking of making a 5-1 tube amplifier for my room. Since 5 channels must be used this is 5x the cost so I have chosen a simple design (a better suggestion??)

I have found these two litle integrated amplifiers and I would like to have some suggestions of which one to use, based on sound quality and volume factors
Thank you

Eli Duttman · 16th June 2010, 12:19 PM

Availability considerations force you to use the 6BM8/ECL82, as Russian production is in the market place.

A PSU using an unsymmetrical 1/2 wave rectifier is a BAD idea, as "standing" DC is present on the rectifier winding.

Check this thread out. A Triad N-77U in the B+ supply is good for approx. 225 mA. That might be enough for 5X channels. The N-77U has dual primaries and works in both "120" and "240" VAC zones.

DF96 · 16th June 2010, 03:36 PM

They both look bad circuits to me. The ECL82 one is dangerous.

neazoi · 17th June 2010, 06:26 AM

ok, they are quick-n-dirty, and cheaper. a safer psu in the ecl82 one is essensial.

have you got an alternative to propose?

picowallspeaker · 17th June 2010, 06:55 AM

Scherzo

aardvarkash10 · 17th June 2010, 07:22 AM

piccolo

revintage · 17th June 2010, 08:03 AM

Go for the beefier ECL86. The pentode can be looked upon as a EL84 with 9W instead of 12W Pa and the triode is one half 12AX7. It sounds great and is available NOS. Probably the P will be cheaper.

If the driver feels wimpy you can always add a DC-connected MOSFET-follower between triode and pentode.

But why not go PP? Easier to get hum free and better performance by adding just one tube.

planet10 · 17th June 2010, 08:17 AM

No bang, no flash, just music!

dave

neazoi · 17th June 2010, 08:56 AM

Thank you all,
I have also thought about OTL (direct coupled or even with capacitor coupling to the speakers), which eliminates the output transformer and reduces cost, but it seems there is nothing around using small tubes...

DF96 · 17th June 2010, 10:30 AM

OTL with small valves means headphones only. This is because of a basic impedance mismatch between transducers and valves: loudspeakers have impedances in the ohm range, valves have impedances in the Kohm range. You either need a transformer to match the impedances, or use lots of valves in parallel to reduce the impedance and, also, heat the room.

16th June 2010, 12:19 PM	#2
Eli Duttman diyAudio Member Join Date: Apr 2004 Location: Plainsboro, NJ	Availability considerations force you to use the 6BM8/ECL82, as Russian production is in the market place. A PSU using an unsymmetrical 1/2 wave rectifier is a BAD idea, as "standing" DC is present on the rectifier winding. Check this thread out. A Triad N-77U in the B+ supply is good for approx. 225 mA. That might be enough for 5X channels. The N-77U has dual primaries and works in both "120" and "240" VAC zones. __________________ Eli D.

17th June 2010, 06:26 AM	#4
neazoi diyAudio Member Join Date: Aug 2007	ok, they are quick-n-dirty, and cheaper. a safer psu in the ecl82 one is essensial. have you got an alternative to propose? __________________ Great DIY site: http://www.neazoi.com

17th June 2010, 07:22 AM	#6
aardvarkash10 diyAudio Member Join Date: Mar 2007 Location: Auckland, NZ	piccolo __________________ Yes, conservatism thrives on low intelligence and poor information. But the liberals in politics... continue to back off, yielding to the supremacy of the stupid. It's turkeys all the way down. - George Monbiot, guardian.co.uk, 6 Feb 2012

17th June 2010, 08:03 AM	#7
revintage diyAudio Member Join Date: May 2007 Location: Eskilstuna, Sweden	Go for the beefier ECL86. The pentode can be looked upon as a EL84 with 9W instead of 12W Pa and the triode is one half 12AX7. It sounds great and is available NOS. Probably the P will be cheaper. If the driver feels wimpy you can always add a DC-connected MOSFET-follower between triode and pentode. But why not go PP? Easier to get hum free and better performance by adding just one tube. __________________ Brgds Lars

17th June 2010, 08:17 AM	#8
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 4	No bang, no flash, just music! dave __________________ community sites t-linespeakers.org, frugal-horn.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA

16th June 2010, 03:36 PM	#3
DF96 diyAudio Member Join Date: May 2007	They both look bad circuits to me. The ECL82 one is dangerous.

17th June 2010, 06:55 AM	#5
picowallspeaker diyAudio Member Join Date: Apr 2007	Scherzo

17th June 2010, 08:56 AM	#9
neazoi diyAudio Member Join Date: Aug 2007	Thank you all, I have also thought about OTL (direct coupled or even with capacitor coupling to the speakers), which eliminates the output transformer and reduces cost, but it seems there is nothing around using small tubes... __________________ Great DIY site: http://www.neazoi.com

17th June 2010, 10:30 AM	#10
DF96 diyAudio Member Join Date: May 2007	OTL with small valves means headphones only. This is because of a basic impedance mismatch between transducers and valves: loudspeakers have impedances in the ohm range, valves have impedances in the Kohm range. You either need a transformer to match the impedances, or use lots of valves in parallel to reduce the impedance and, also, heat the room.

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