The 6AV5's cranked to about 37 watts of dissipation, about 3 times the recommended maximum. You will see the plate glowing, but I checked the screen grid carefully, and it was not glowing. This should aleviate any fears about violating the 175 volt screen rating. Most of the red glow comes from the pilot light on the power supply. The room lights were off for this picture. B+ is 380 volts, 355 volts across the tube, plate current is 105mA.
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And for tonights listening pleasure, the 6LW6, in triode mode. Setup is the same as before, except that it likes to be run hot (400 volts at 110 mA) with the 8 ohm load on the 16 ohm tap. This presents a 1500 ohm load to the tube. Power is 15 watts at .8% distortion. The single stage driver in this board does not have enough gain to drive this tube to clipping. Bass is the best that I have heard come out of my speakers. Note that all meters are slammed to the right, this amp wants more voltage, and more drive, I ran out of both.
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All of the testing that I did for this thread was in "triode strapped" mode, G2 connected to plate, drive on G1, since the original point was to see if a triode connected 6AV5 really could imitate a 6B4. After I did this, I listened to a few different sweep tubes for the next few nights and concluded that the 6AV5 really did sound good. It beats a triode strapped 6L6. The 6LW6 definitely had the best bass, but it wanted more drive, and more voltage than my power supply could give it. I was experimenting with that tube when an oops with the screwdriver blew up the CCS chip on the driver board. After fixing this, I set up to test triode strapped 807's and hurricane Wilma came along and spoiled the party. I will try screen drive once I put my lab back together.
This is a very interesting thread!
I have a pair of Sovtek 6B4G (single plates) and I´m waiting for a pair of Billington Gold (chinese).
The plan is to build a DRD amp with Lundahl LL1664/60mA OPTS and LL1621/40mA wired as plate chokes for the driver stage.
Seems that I should ge me some of those 6AV5´s too then!
I have a pair of Sovtek 6B4G (single plates) and I´m waiting for a pair of Billington Gold (chinese).
The plan is to build a DRD amp with Lundahl LL1664/60mA OPTS and LL1621/40mA wired as plate chokes for the driver stage.
Seems that I should ge me some of those 6AV5´s too then!
I have the schematic in PDF format. It is almost 2 MB in size so I can't post it here. I don't see a way to include it in the forums email feature either. Send me an email via the forums email feature (or get the address off of my web site) and I will email it to you. Don't post your email address (or mine!) directly on this forum or any other place on the web in plain text format. Your mail box will be filled with spam in 2 days.
It is interesting that this amp operated the 6AV5's well above the published plate voltage ratings. Who would do such things?
It is interesting that this amp operated the 6AV5's well above the published plate voltage ratings. Who would do such things?
The Bogen DB-130 schematic is on the internet:
http://members.shaw.ca/pacifictv1/bogendb1301.jpg
http://members.shaw.ca/pacifictv1/bogendb1301.jpg
Interesting, I have a DB230 that also uses the 6AV5GA, and the schematic is quite different with a more reasonable ~400V on the output tubes. The driver stage is also a standard 7199 gain+cathodyne. I haven't rebuilt it yet, but it looks to have great potential, with regulated screens on the output tubes, and dual-mono supply except for the output B+.
Hi All, yes, the 6AV5 is an interesting useful tube, have been running these in a pair if p-p amps for the last few weeks, triode strapped with about 320V across them and self bias, dissipating about 20W, they have stayed balanced with no signs of unwanted glow.
Sound, pretty good, I agree with Sir Tubelab, these sound better than triode strapped 6L6s, and can rock out rather well, and the subtle things are there, not so far from the 6336 SE amp that is reference amp just now.
Well worth investigation if you find some, was inspired to try them after having some 6DQ6s as a 6B4 replacement in said P-P amps.
And Tubelab is right, the older GE 6AV5s are pretty robust... And no top cap to worry about.
Hope this info useful, there still some 'finds' out there in pile of sweep tubes at hamfests and such.Enjoy!
Cheers,
'tron
Sound, pretty good, I agree with Sir Tubelab, these sound better than triode strapped 6L6s, and can rock out rather well, and the subtle things are there, not so far from the 6336 SE amp that is reference amp just now.
Well worth investigation if you find some, was inspired to try them after having some 6DQ6s as a 6B4 replacement in said P-P amps.
And Tubelab is right, the older GE 6AV5s are pretty robust... And no top cap to worry about.
Hope this info useful, there still some 'finds' out there in pile of sweep tubes at hamfests and such.Enjoy!
Cheers,
'tron
slideman82 said:
It's supposed I studied English 7 years! That stands for "(...)Is this schematic avaible(...)"
radiotron said:
What about running them in pentode mode in a PP amp? I'm more interested on this, but I'm afraid I can get some 6AU5, someone said they were similar. You mentioned 6DQ6... have you seen those Aussy guitar amps with them as output? And where I can take a look at those 6B4 schematics?
Fuling said:
In this corner have used self bias, approx 1k in cathode circuit, with a plate supply of about 345-350V, giving about 50mA through tube. Tried in in both SE and P-P setup without dramas. At this time tube is triode strapped with 180 ohm carbon composition resistor from screen to plate, and same for grid stopper, right at tube base tag.
Cheers,
'tron
slideman82, yes, I think I know the amp you're thinking of, was a 1960s Electronics Australia design for P-P 6DQ6s as pentodes, would have to hunt around for a schematic, from memory it is very basic, screens were set about 150v from a zener string, and driven by 12AU7 as cathode coupled phase inverter.
I thought maybe I had some of those AV5's? But not today.
What I found instead was Qty3 GE 6GT5A in NOS boxes.
Two of the boxes are marked X and "low" on the end flap.
All the Getters look fine. And I have no idea if these tubes
in the marked up boxes are actually the bad tubes or not.
I havn't tested them myself yet, My tester is a SICO that
only does emission and short tests. I've never fired it up
for concern that it might need to be re-capped first.
Kinda strange, these looked to be Octal tubes, but now
I see they have no base and 9 small pins straight out
the glass. Certainly too big to fit a normal 9 pin socket.
What the heck is this?
Now I wonder if my tester even has this odd socket?
I left it in my Neighbor's garage in the back of the old
Hammond M3 organ we were fixin to refurbish... So I
can't just whip it out this second and have a looksee.
What I found instead was Qty3 GE 6GT5A in NOS boxes.
Two of the boxes are marked X and "low" on the end flap.
All the Getters look fine. And I have no idea if these tubes
in the marked up boxes are actually the bad tubes or not.
I havn't tested them myself yet, My tester is a SICO that
only does emission and short tests. I've never fired it up
for concern that it might need to be re-capped first.
Kinda strange, these looked to be Octal tubes, but now
I see they have no base and 9 small pins straight out
the glass. Certainly too big to fit a normal 9 pin socket.
What the heck is this?
Now I wonder if my tester even has this odd socket?
I left it in my Neighbor's garage in the back of the old
Hammond M3 organ we were fixin to refurbish... So I
can't just whip it out this second and have a looksee.
In the never ending quest to make things cheaper, manufacturers figured out that the base wasn't needed. The Novar (9 pin) and Duodecar (12 pin) are these baseless tubes. GE called them both "Compactrons". The Chinese are making new production sockets in ceramic for these tubes.
There are a few 9 pin tubes out there with fatter pins that don't fit these sockets. You can make them fit, but then you can't put the normal (thin pins) tubes back in that socket.
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