Heptode preamp

Arthur Dent · 05-17-2008, 08:46 PM

I have an old amp that had a 6AU6 preamp pentode, and it sounded completely amazing, though very noisy. I had swapped that tube out for a 6BA6, which sounded similar with a little less noise.

Then, I found something interesting: a 6BE6. It is a seven-pin heptode, which I found had a pinout and specs which would allow it to be directly swapped with the pentodes. I tried it of course, and it sounded even better in my opinion, and the amp is now dead quiet!

I have never heard of that being done, so I just wanted to pass on that tip to anyone who may be interested.

Alex/Tubewonder · 05-17-2008, 10:50 PM

That's analogous to strapping pentode as triode. Heptode strapped as pentode. How did you wire grid 3?

Rob Mercure · 05-18-2008, 01:19 PM

If you like your current result try using these bottles to mix two signals - much more elegant than the junction of two isolating resistors. Better yet try a 6L7 - if the grid cap isn't off putting - specifically desinged for audio work as a mixer/control tube.

Rob

Arthur Dent · 05-20-2008, 12:01 AM

Alex, grid 3 is jumpered to the cathode. I've never used a heptode before, so I didn't know what else to do with it. I guess it's supposed to be a second control grid, but I am unsure as to how I could use that beneficially. Wire it to grid 1?

Rob, that's a good idea. I haven't had any reason to mix two signals yet, but I'll keep that in mind.

05-17-2008, 08:46 PM	#1
Arthur Dent Member Join Date: Oct 2006 Posts: 66	Heptode preamp I have an old amp that had a 6AU6 preamp pentode, and it sounded completely amazing, though very noisy. I had swapped that tube out for a 6BA6, which sounded similar with a little less noise. Then, I found something interesting: a 6BE6. It is a seven-pin heptode, which I found had a pinout and specs which would allow it to be directly swapped with the pentodes. I tried it of course, and it sounded even better in my opinion, and the amp is now dead quiet! I have never heard of that being done, so I just wanted to pass on that tip to anyone who may be interested.

05-17-2008, 10:50 PM	#2
Alex/Tubewonder Senior Member Join Date: Jul 2006 Location: Goteborg, Sweden Posts: 144	That's analogous to strapping pentode as triode. Heptode strapped as pentode. How did you wire grid 3? __________________ Aleksander Niemand Tubewonder amps Life's a party but you get invited only once

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Mod a Preamp	guitarkirkster	Mods & Tweeks	2	04-01-2008 04:05 AM
Preamp too loud	Hallingamp	Theory & Design	3	01-13-2008 02:24 PM
hafler t2 preamp	slagg	Maintenance, Troubleshooting & Repair	5	12-22-2007 07:14 PM
Amp Tubes / Using Preamp out	silentbry	Maintenance, Troubleshooting & Repair	11	02-10-2007 06:33 PM
ADA preamp	brewu22	Maintenance, Troubleshooting & Repair	1	11-18-2006 08:03 PM

05-18-2008, 01:19 PM	#3
Rob Mercure Lifetime Member Join Date: May 2006 Location: Wise, Virginia Posts: 624	If you like your current result try using these bottles to mix two signals - much more elegant than the junction of two isolating resistors. Better yet try a 6L7 - if the grid cap isn't off putting - specifically desinged for audio work as a mixer/control tube. Rob

05-20-2008, 12:01 AM	#4
Arthur Dent Member Join Date: Oct 2006 Posts: 66	Alex, grid 3 is jumpered to the cathode. I've never used a heptode before, so I didn't know what else to do with it. I guess it's supposed to be a second control grid, but I am unsure as to how I could use that beneficially. Wire it to grid 1? Rob, that's a good idea. I haven't had any reason to mix two signals yet, but I'll keep that in mind.

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