• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

6146B?

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#2
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#7
Not a good audio tube, the screen is somewhat prone to exploding if over driven... shorting the tube... I have never heard anyone at any time say that they liked how they sound. Of course that doesn't mean much.

_-_-bear

PS. spectacularly unpopular for modulators in ham radio...
 
#8
Thanks,

That's more less what I'm looking for. I notice that it handles highish plate voltage, and thought it looked like a decent candidate for my Bogen overhaul.

I've seen the Acro and an old theater amp schematic with them, but your point is probably why the schematics are few and far between.

Blair
 
#9
You should not worry about 6146B as a candidate for the output tubes.
I have not heard "bad sounding" tubes yet, but some bad sounding amplifiers.

The final result depends mostly on the design and how the amplifier is "fine tuned", not what tubes are used.
 
#11
artosalo said:
You should not worry about 6146B as a candidate for the output tubes.
I have not heard "bad sounding" tubes yet, but some bad sounding amplifiers.

The final result depends mostly on the design and how the amplifier is "fine tuned", not what tubes are used.
Click to expand...

i agree, it is not the tubes per se, but what you do with it that matters....😀

these are a pair of monoblocks done by a local diy'er in Manila:http://www.wiredstate.com/forum/viewtopic.php?f=53&t=22509

An externally hosted image should be here but it was not working when we last tested it.

6146006.jpg
 
#12
What I heard about the 6146 is that it's OK for non-continuous use, such as in transmitting, but is likely to overheat in continuous use, such as playing music in an audio amp. Some early audio amps used it, but the more robust and reliable 807s and KT88s soon took over.
 
#13
ray_moth said:
What I heard about the 6146 is that it's OK for non-continuous use, such as in transmitting, but is likely to overheat in continuous use, such as playing music in an audio amp. Some early audio amps used it, but the more robust and reliable 807s and KT88s soon took over.
Click to expand...

Nah you just have to pay attention to the CCS vs ICAS ratings. Most people consider it a "ham" tube so it gets little attention.
 
#14
🙂

It's tough to decide to commit to a tube that has such a spread of opinions. Tony, I've seen those, and they look nice! I wonder what they sound like.

It just seemed like a good, inexpensive candidate to try for good power. They can be had on eBay for $20-30pr in the states.
 
#15
My understanding is that they were strongly marketed by RCA for both ham and audio use. When they were being flogged for audio, the UL connection was also becoming popular, with most companies switching to it from a pentode connection. The problem that arose was that the 6146 couldn't take a lot of voltage on the screen so they were failing miserably, and soon abandoned for UL audio use. I think the only concern for audio is that they need to run as pentodes with a regulated screen supply.
 
#16
prairieboy said:
My understanding is that they were strongly marketed by RCA for both ham and audio use. When they were being flogged for audio, the UL connection was also becoming popular, with most companies switching to it from a pentode connection. The problem that arose was that the 6146 couldn't take a lot of voltage on the screen so they were failing miserably, and soon abandoned for UL audio use. I think the only concern for audio is that they need to run as pentodes with a regulated screen supply.
Click to expand...
Why not capacitively couple the UL tap to the screen grid and provide an R to drop the screen voltage to something safer? It sounds do-able, but I haven't tried it.
 
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#17
deicide67 said:
🙂

It's tough to decide to commit to a tube that has such a spread of opinions. Tony, I've seen those, and they look nice! I wonder what they sound like.

It just seemed like a good, inexpensive candidate to try for good power. They can be had on eBay for $20-30pr in the states.
Click to expand...

if i were you, i'd try tv tubes instead, they are cheap also.....the 6FW5, 6AV5 for example is $4 a bottle....the 6GV5 is just a $1....
 
#18
deicide67 said:
🙂

It's tough to decide to commit to a tube that has such a spread of opinions...
Click to expand...

6146B is fine for pentode connected push-pull amplifier, but not suitable for UL-connection.
The reason is that the screen voltage must be essentially lower that the anode voltage.

One opinion can be found from RCA data sheets and follow their suggestion.

With: Ua = 600 V, Ug2 = 200 V, Ug1 = -47 V (fixed bias) and 5k6 output transformer the expected output level is 96 W.

This means that, say 50 W can be taken from a pair of 6146B with VERY good linearity and low distortion.
Such amplifier do not "sound" bad.
 
#19
Tony said:
if i were you, i'd try tv tubes instead, they are cheap also.....the 6FW5, 6AV5 for example is $4 a bottle....the 6GV5 is just a $1....
Click to expand...

These tubes are very similar. Both have designed for low screen voltage operation.
Therefore these are not suitable for UL-operation, but work fine as pentode connected with 150 to 200 V at the screen.
 
#20
As for how 6146Bs sound, it's a matter of loadlines and the resulting harmonic "personality" of the type. If these tend to produce hots of H5 and above, they may need some local NFB to clean 'em up, as does the 807. If that's the case, you have the choices of parallel NFB or cathode NFB. The low screen voltage spec pretty much precludes UL operation. In that case, regulated screens and local NFB (if required) will probably give excellent sonic performance.

Otherwise, expect the usual pentode performance: under damped bass and "edginess".
 
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