6AV5GA amp?

[Bob_345]

Does anyone around here know of an amp schematic that uses a 6AV5GA tube? Ive been looking around and cant quite seem to find any schematics that use this tube. Thanks in advanced.

 

[leadbelly]

What cracks me up is that when you posted this, the thread immediately below yours was about just such an amp!

http://www.diyaudio.com/forums/tubes-valves/151206-posted-new-p-p-power-amp-design.html

You seem to be allergic to the Search button, or maybe you only searched on 6AV5GA and not just 6AV5, as there are a few threads on it.

 

[Eli Duttman]

In addition to what LB said, triode wired 6AV5s exhibit electrical behavior "=" to the 2A3/6B4G/6A3 group. That means all sorts of circuits, both SE and PP, are available and you can AC heat with impunity.

 

[smoking-amp]

6AV5 is the same as 6BQ6 except without the plate cap, 11 Watt diss, octal. Pete's amp is using 6GV5/6JN6 which are 17.5 watt compactron tubes, although the tube characteristics are quite similar otherwise. Seems to me that Tubelab did some amps using 6AV5/6BQ6. Maybe have to search on 12AV5, 12BQ6.

 

[leadbelly]

6AV5 is the same as 6BQ6 except without the plate cap, 11 Watt diss, octal. Pete's amp is using 6GV5/6JN6 which are 17.5 watt compactron tubes, although the tube characteristics are quite similar otherwise. Seems to me that Tubelab did some amps using 6AV5/6BQ6. Maybe have to search on 12AV5, 12BQ6.

I stand corrected, although I seem to remember Tubelab suggesting that he came across a whole bunch of sweep tubes that looked like they had identical plates inside, all of which looked like the 17W, except that they were in different envelopes, and the 6AV5 was one of these.

 

[llwhtt]

McIntosh used them in the MI-200.

Craig

 

[Bandersnatch]

hey-Hey!!!,
6AV5 make nice linestage tubes as well. Shunt reg with a 0A3 tube to give their g2 75V, B+ of ~180, plate load between 400 and 1000 Ohms, cathode R of 100R with suitable bypass cap. Idle current is 50 mA/tube. Needs a quiet B+ though as resistive loading pentodes gives minimal PSRR.
cheers,
Douglas

 

[Tubelab_com]

OK, someone mentioned my name and the 6AV5 in the same sentence.

First off, a newcommer asked about schematics using the 6AV5GA. The standard in vintage amps has to be the Bogen DB-130. I have the schematic and complete service manual in PDF but they are huge (7 MB). It is an overly complex integrated mono amplifier that makes a conservative 35 watts. Seriously, just put 6AV5GA in the search box and you will get 2 pages of hits than include some schematics and some of my antics with these tubes.

6AV5 is the same as 6BQ6 except without the plate cap, 11 Watt diss, octal....QUOTE]

There is some misinformation here. It is hard to say that the 6BQ6 and the 6AV5 are identical since there are so many different versions of both tubes that aren't even identical themselves. First off the 6AV5 comes in GT and GA versions. The 6BQ6 comes in GT, GTA, GTB and GA versions. There are exceptions but for the most part the 6AV5GT, 6BQ6GT, GTA and GTB are thin (1.125 inch diameter) tubes. They both are indeed rated for 11 watts. The first photo shows both tubes.

I stand corrected, although I seem to remember Tubelab suggesting that he came across a whole bunch of sweep tubes that looked like they had identical plates inside, all of which looked like the 17W, except that they were in different envelopes, and the 6AV5 was one of these.

Both tubes also come in a "GA" version. The spec sheets for both the 6BQ6GA and the 6AV5GA show 11 watt dissipation ratings, but the tubes are obviously bigger. The problem arises from the fact there are several different versions of each tube with different plate structures. It appears that the "growth" wasn't instant. The various manufacturers just kept making the plates bigger and bigger. Some can dissipate far more power than others. The second photo shows three different 6BQ6GA tubes. The two tubes on the right are both GE 6BQ6GA's. The tube on the far right does indeed have the same "17watt plate" found in dozens of different GE sweep tubes including some 6AV5GA's, and all of the 17.5 watt GE compactrons.

The same thing goes with 6AV5GA's. The third photo shows three different 6AV5GA's. All of these have "17 watt plates". Note the GE on the left has the same plate structure as the "17 watt" GE 6DQ6GA. I have several GE 6AV5GA's with the same plate structure found in the middle 6BQ6GA.

Anyone who ever worked in TV repair knows that the sweep tubes died a lot. As a result the manufacturers kept improving them, often putting in plates that could handle more than their published ratings. The TV set manufacturers knew this and often pushed the ratings in order to make bigger TV's. So, what happens when a TV repair man sticks a "small" 6AV5GA into a TV designed for one of the new steroid enhanced 17 watt 6AV5GA's. Meltdown occurs often taking out the flyback transformer and damper tube. Ge realized this issue so they created the 6FW5. It IS a 6AV5GA with the 17 watt plate, no wimpy plates were ever put into 6FW5's.

So, yes there are a lot of 17 watt sweep tubes, including some but not all 6AV5GA's and 6BQ6GA's. All 6FW5's are 17 watt versions of the 6AV5GA and can be substituted for any 6AV5GA.

In addition to what LB said, triode wired 6AV5s exhibit electrical behavior "=" to the 2A3/6B4G/6A3 group. That means all sorts of circuits, both SE and PP, are available and you can AC heat with impunity.

Again this is partially true. As the vacuum tube manufacturing volumes declined manufacturers closed some assembly lines and consolidated others. Hence GE's decision to use the same plate structure in most of their small sweep tubes. When the production volumes of a specific type number declined below profitability it dissapeared, forever....except when there was a contract (often military) that had to be fulfilled. Some manufacturers (especially Sylvania) found a creative solution. They went to the contract holder and worked out a substitute that worked in their particular application. These tubes were sold to the contract owner only and were never intended to work in all applications. Now 30+ years later we find them on the surplus market. Yes there are tubes out there that are labled 6B4GA (a DHT) that contain the "guts" of a 6AV5GA (a pentode sweep tube). There is no way that these tubes are identical or even similar. In fact the imposter 6B4 will usually test bad as a 6B4 in most tube testers. For more info:

http://www.diyaudio.com/forums/tube...w-anything-about-6av5ga.html?highlight=6av5ga

http://www.diyaudio.com/forums/tubes-valves/74650-edcor-meets-6av5.html?highlight=6av5ga

 

[seamas]

The bogen cha75 used 4 6av5ga tubes to produce 75 watts.

 

[quadtech]

See the schematic posted by Soren here -

diytube.com :: View topic - New SET Amp

diytube.com :: View topic - 6AV5GA triode strapped?

 

[alexg]

I did a 6AV5 SE amp, triode strapped with 800R cathode resistor, plate voltage of around 320VDC. I used a 12at7 as input/driver.

Sounds very decent.