[mordy]

I'm pretty sure you can't. I was referring to triode-pentodes, one triode and one pentode in the same envelope as the triode-hexodes you mentioned.


Very good point. The idea of using just the triode or a strapped pentode/hexode makes more sense, although I'm not sure how these tubes react if you "defuse" one of the parts. Taking as an example the ECF82 I mentioned, we would only need to use pins 1, 8, and 9, and we would isolate the triode.



The problem would be, of course, the adapters. I need to get into DIYing those things...

There are Head-Fi members who make custom adapters for sale and people who make them themselves for their own use. If you read the specifications and pick tubes within the specs of the amp usually there are no problems using the triode section of a tube.
With the scarcity of tubes and the prices going up I predict that we are going to see more and more use of lesser known tubes being used as strapped triodes.

 

[TrollDragon]

Looks like a ton of work for some questionable gains, but to each their own.

 

[jonathan c]

“… warning, warning … heater, heater …”:

 

[JazzVinyl]

“… warning, warning … heater, heater …”:

Someone on another site pointed out to me that this module is tiny. inexpensive, and puts out very clean 12v DC from 120 VAC input and is perfect for the job of powering 12v tube heaters. He puts them _inside_ his tube amp builds to let them use 12v tubes (that are so much less expensive than their 6v brethren and can be found in true NOS condition):

https://www.amazon.com/MEAN-WELL-MDR-20-12-DIN-Rail-Supply/dp/B00DECZVY6

 

[Cognomen]

Looks like a ton of work for some questionable gains, but to each their own.

I agree about the prospect for sonic gains but would enjoy learning a bit more. I've thought of breadboards and test tube sockets but don't like the exposure to shocks and electrocution so I'd like to figure out a way to put it or myself in a cage.

 

[mordy]

“… warning, warning … heater, heater …”:

I have some experience with external power supplies and it is not that difficult to use them and I don't consider them dangerous.
You need the PS and then an inexpensive voltage regulator to set the voltage you desire.
The modular 1.67A PS that JV suggested is too small for my taste. In the interest of economy I scavenged old power supplies from discarded computers. They are rated for much higher current draw and I use 15-24A power supplies to use the 5A power tubes 6336/6528 which effectively are a triple 6080 tube.
IMHO the sonic benefits aren't subtle with much more punch and slam.
The main drawback is that such a set-up is quite ugly to look at.

 

[dany9107]

Hi guys, I recently had a problem with my Little Dot MK3, I hear a constant buzzing in my headphones that doesn't go away. When something is playing it doesn't bother you but where the sounds are turned down you can hear it. I've already tried replacing both the power tubes and the others. What do you suggest I do?

 

[triod750]

Sounds as if it is some kind of earth loop. Some tubes I have used have been very prone to hum. I have solved this by making a Faraday's cage from aluminum foil around the tube and then connected this with thin copper wire to the screw that holds the front plate of my Little Dot MKIVSE on the right side, beside the volume control. I loosened the screw a little, wound the thin copper wire around it and screwed it back. Immediately when the other end of the copper wire touches the aluminum foil the tube(s) become totally silent. I just make a 'hook' on the end and pierce it through.
Same procedure when I use external power supply; I connect ground on the psu to this grounding point on the amp. Dead silence. Before that I could have hum issues when I used some double triodes as input tubes via adapter.

 

[triod750]

6C5/6C5G/6C5GT/G can be used in the same adapter as 6J5 type tubes and are on par with 6J5 in my experience. The all metal 6J5/6C5 tubes are usually cheaper and with good sound quality. You don't need NOS tubes. Used tubes have a long life left, mostly. Don't expect them to fail on you or to sound worse in any way.
But they are single triodes, of course, and a lot of people favour singles for sound quality compared to their double triode brethrens.

Also, the single triode 6C4 is half the double triode 12AU7/ECC82 and can be used via adapter as input tubes without external psu. I ordered my adapters from @Deyan , member on this forum.

 

[warp2600]

Hi guys, I recently had a problem with my Little Dot MK3, I hear a constant buzzing in my headphones that doesn't go away. When something is playing it doesn't bother you but where the sounds are turned down you can hear it. I've already tried replacing both the power tubes and the others. What do you suggest I do?

Try connecting your amp to a different wall outlet.

 

[Cognomen]

I have some experience with external power supplies and it is not that difficult to use them and I don't consider them dangerous.
You need the PS and then an inexpensive voltage regulator to set the voltage you desire.
The modular 1.67A PS that JV suggested is too small for my taste. In the interest of economy I scavenged old power supplies from discarded computers. They are rated for much higher current draw and I use 15-24A power supplies to use the 5A power tubes 6336/6528 which effectively are a triple 6080 tube.
IMHO the sonic benefits aren't subtle with much more punch and slam.
The main drawback is that such a set-up is quite ugly to look at.

I'm not nearly as concerned by the power supply as by high voltage of other pins that look exposed on breadboards and on tube tester sockets.

 

[Cognomen]

Try connecting your amp to a different wall outlet.

I believe I elimated a humming ground loop by plugging all my audio into one outlet which I believe eliminates a loop. My smartphone can cause some minor noises but not steady hum. The phone has no effect if about 1.5 meters away. Occasionally I have rotated the amp 90 degrees and it eliminated noise. If other tubes are available, it might be worthwhile to try them to see if the current tubes are the culprit.

 

[mordy]

I'm not nearly as concerned by the power supply as by high voltage of other pins that look exposed on breadboards and on tube tester sockets.

If you use commercially available well made adapters single or dual there is no risk of electric shock.

 

[Cognomen]

If you use commercially available well made adapters single or dual there is no risk of electric shock.

Yes I agree about adapters! I was thinking of breadboards and tube test sockets. I may find that if I want to keep it safe and can't figure out some sort of safety cage, I'll go the adapter route. I'm familiar with them and have quite a few.

 

[Cognomen]

I have some experience with external power supplies and it is not that difficult to use them and I don't consider them dangerous.
You need the PS and then an inexpensive voltage regulator to set the voltage you desire.
The modular 1.67A PS that JV suggested is too small for my taste. In the interest of economy I scavenged old power supplies from discarded computers. They are rated for much higher current draw and I use 15-24A power supplies to use the 5A power tubes 6336/6528 which effectively are a triple 6080 tube.
IMHO the sonic benefits aren't subtle with much more punch and slam.
The main drawback is that such a set-up is quite ugly to look at.

On a little dot mkI, II, III, or IV? That's about 4X the max ampere for the bypassed transformer and possibly many other parts in some of them...