-
WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!
Am I mad? Judge me...and leave a recommendation.
- Thread starter Yorkshire Mouth
- Start date
Gosh, you've demo'd all of them?
(I'm not a tube amp owner or ever care to buy one. But I wouldn't make such a sweeping statement without qualification)
LOL. Godspeed, you, then.
mhardy6647
Grand Contributor
- Joined
- Dec 12, 2019
- Messages
- 11,412
- Likes
- 24,773
Indeed. As they say:
The Boston Museum of Science has a nice one.
(random internet image; not my photo - but I have seen the demo a couple of times and it's dandy)
EdW
Senior Member
I always tried to work with one hand behind my back when delving into valve (tube) circuits! Back in the late 60’s I built quite a few amps using old UK WW2 surplus power transformers, chokes and paper smoothing caps. A good idea to put a bleed resistor across the caps so that you didn’t get a shock a week later!
Buy some old radio, 1950's or so and get rid of the case and make certain that there is no access to high voltage parts so nobody gets killed. The other option, there are some cheap Chinese tube amps (number of tubes usually limited if that matters).
I apologize if that was suggested already, I did not read the entire thread.
I apologize if that was suggested already, I did not read the entire thread.
mhardy6647
Grand Contributor
- Joined
- Dec 12, 2019
- Messages
- 11,412
- Likes
- 24,773
. . .
The cheapest route to glowing but useless tubes, in a 'plug and play' package, would be a two vacuum tube headphone amp or buffer available under any of about a thousand Chinese brand names. Thirty to fifty USD will get one. Almost all of them operate at low voltages and require no output loading. Most of them use small-signal triodes or pentodes, so the tubes themselves get only warm. All in all, they're (relatively) safe (assuming that the construction and circuitry is even close to reasonable standards!) and could be used with minimal worries as a display.
Here's an example: this is a headphone amp, and unfortunately only has one tube (a twin triode; two tubes in one envelope):
Here's a better example: This one is sold as a two-tube preamp, but it's pretty much cut from the same cloth as the above-mentioned buffers.
IN FULL DISCLOSURE: In many -- perhaps most (or even all) cases -- these little boxes cheat by sticking little orange or even yellow LEDs under the tubes to make them light up more vividly than they actually do. The little FX Audio box above is an example. Note the sickly jaundiced glow from the LEDs under the tubes.
The best bet, IMO, would be to get two 'plinker' (inexpensive, even bad, used tubes that are basically worthless but with good filaments so that they'll glow), two sockets, some wire, and a "Hammond box" (or other little enclosure, bought or DIY) and build a box that is wired to light the filaments of the two tubes with a low voltage (generally 6 or 12 V, depending on the tube type). A 'wall wart' AC transformer will suffice nicely, as long as it can deliver the current required by the tube filaments. Tube manuals* list the filament requirements very plainly.
Then there's the brute-force approach. Assuming 120 VAC mains: Get yourself ten 12V filament 'plinker' tubes and wire all of the filaments in series. Connect one leg of the 10-tube-string to one prong of the AC mains, and the other leg to the other prong! For best results, add a fuse and, ideally, an isolation transformer. Plug in and enjoy.
Great for the holidays!
There is one other cheap-ish option, which I shall post separately.
____________________
* Tube information (click on the 'spoiler' if interested enough!)
Since I didn't actually respond to the question -- I shall.
The cheapest route to glowing but useless tubes, in a 'plug and play' package, would be a two vacuum tube headphone amp or buffer available under any of about a thousand Chinese brand names. Thirty to fifty USD will get one. Almost all of them operate at low voltages and require no output loading. Most of them use small-signal triodes or pentodes, so the tubes themselves get only warm. All in all, they're (relatively) safe (assuming that the construction and circuitry is even close to reasonable standards!) and could be used with minimal worries as a display.
Here's an example: this is a headphone amp, and unfortunately only has one tube (a twin triode; two tubes in one envelope):
Here's a better example: This one is sold as a two-tube preamp, but it's pretty much cut from the same cloth as the above-mentioned buffers.
IN FULL DISCLOSURE: In many -- perhaps most (or even all) cases -- these little boxes cheat by sticking little orange or even yellow LEDs under the tubes to make them light up more vividly than they actually do. The little FX Audio box above is an example. Note the sickly jaundiced glow from the LEDs under the tubes.
The best bet, IMO, would be to get two 'plinker' (inexpensive, even bad, used tubes that are basically worthless but with good filaments so that they'll glow), two sockets, some wire, and a "Hammond box" (or other little enclosure, bought or DIY) and build a box that is wired to light the filaments of the two tubes with a low voltage (generally 6 or 12 V, depending on the tube type). A 'wall wart' AC transformer will suffice nicely, as long as it can deliver the current required by the tube filaments. Tube manuals* list the filament requirements very plainly.
Then there's the brute-force approach. Assuming 120 VAC mains: Get yourself ten 12V filament 'plinker' tubes and wire all of the filaments in series. Connect one leg of the 10-tube-string to one prong of the AC mains, and the other leg to the other prong!
For best results, add a fuse and, ideally, an isolation transformer. Plug in and enjoy.Great for the holidays!
There is one other cheap-ish option, which I shall post separately.
____________________
* Tube information (click on the 'spoiler' if interested enough!)
RCA tube manuals available for free download at https://www.worldradiohistory.com/BOOKSHELF-ARH/Bookshelf-RCA.htm
Here's a good one with "modern" but not too modern tube types, e.g.,
Here's a good "plinker" tube choice that will light nicely as long as the vacuum and the filament are both intact. As you see, it needs 6 VAC (give or take) at 0.3 amps.
Wire two of these (filaments only) in parallel and Bob's your Uncle.
Zillions of 6AU6s have been made -- virtually every FM radio or tuner had two to four of them. Easy to find old ones that are still good if one looks in the right places. Note that the filament connections are pins 3 and 4. Nothing else has to be hooked up to light the filament. Just feed it about 6 volts.
Here's a good one with "modern" but not too modern tube types, e.g.,
Here's a good "plinker" tube choice that will light nicely as long as the vacuum and the filament are both intact.
As you see, it needs 6 VAC (give or take) at 0.3 amps.Wire two of these (filaments only) in parallel and Bob's your Uncle.
Zillions of 6AU6s have been made -- virtually every FM radio or tuner had two to four of them. Easy to find old ones that are still good if one looks in the right places.
Note that the filament connections are pins 3 and 4. Nothing else has to be hooked up to light the filament. Just feed it about 6 volts.
Last edited:
OP
Yorkshire Mouth
Major Contributor
- Thread Starter
- #67
. . .
Since I didn't actually respond to the question -- I shall.
The cheapest route to glowing but useless tubes, in a 'plug and play' package, would be a two vacuum tube headphone amp or buffer available under any of about a thousand Chinese brand names. Thirty to fifty USD will get one. Almost all of them operate at low voltages and require no output loading. Most of them use small-signal triodes or pentodes, so the tubes themselves get only warm. All in all, they're (relatively) safe (assuming that the construction and circuitry is even close to reasonable standards!) and could be used with minimal worries as a display.
Here's an example: this is a headphone amp, and unfortunately only has one tube (a twin triode; two tubes in one envelope):
Here's a better example: This one is sold as a two-tube preamp, but it's pretty much cut from the same cloth as the above-mentioned buffers.
View attachment 352717
IN FULL DISCLOSURE: In many -- perhaps most (or even all) cases -- these little boxes cheat by sticking little orange or even yellow LEDs under the tubes to make them light up more vividly than they actually do. The little FX Audio box above is an example.
The best bet, IMO, would be to get two 'plinker' (inexpensive, even bad, used tubes that are worthless but with good filaments so that they'll glow), two sockets, some wire, and a "Hammond box" (or other little enclosure, bought or DIY) and build a box that is wired to light the filaments of the two tubes with a low voltage (generally 6 or 12 V, depending on the tube type). A 'wall wart' AC transformer will suffice nicely, as long as it can deliver the current required by the tube filaments. Tube manuals* list the filament requirements very plainly.
Then there's the brute-force approach. Assuming 120 VAC mains: Get yourself 10 12V filament tubes and wire all of the filaments in series. Connect one leg of the 10-tube-string to one prong of the AC mains, and the other leg to the other prong!
Great for the holidays!
View attachment 352721
There is one other cheap-ish option, which I shall post separately.
____________________
* Tube information (click on the 'spoiler' if interested enough!)
RCA tube manuals available for free download at https://www.worldradiohistory.com/BOOKSHELF-ARH/Bookshelf-RCA.htm
Here's a good one with "modern" but not too modern tube types, e.g.,
Here's a good "plinker" tube choice that will light nicely as long as the vacuum and the filament are both intact.
Wire two of these (filaments only) in parallel and Bob's your Uncle.
View attachment 352720
Bloody superb post.
mhardy6647
Grand Contributor
- Joined
- Dec 12, 2019
- Messages
- 11,412
- Likes
- 24,773
These are cheap.
No one's really quite sure what if anything the four tubes do in these "hybrid" amps, although they are in the circuit (i.e., if the tubes are taken out, no sound will be produced by loudspeakers connected to it). It might even be that the filaments are used as (only) resistors
At any rate, there are tubes and they do light up (although, again, typically their light is augmented by LEDs under them!). BUT the tube filaments themselves do glow visibly in these rascals!
The one pictured above, albeit a bit blurrily, is actually at my house This one was sold under the "Monoprice" brand. In the US, Parts Express still sells a variant thereof -- with higher advertised output power (the output section of these amps is solid state, despite the presence of two power output tubes on top!).
The drawback to these monstrosities (sold worldwide under many brand names): the tubes -- at least the two larger ones -- actually do get quite hot (i.e., they dissipate a fair amount of power), so they aren't quite benign.
Oooh. I just discovered that @amirm actually reviewed one of these.
www.audiosciencereview.com
Here's the current listing of cheap tube junk available from Parts Express FWIW:
No one's really quite sure what if anything the four tubes do in these "hybrid" amps, although they are in the circuit (i.e., if the tubes are taken out, no sound will be produced by loudspeakers connected to it). It might even be that the filaments are used as (only) resistors
At any rate, there are tubes and they do light up (although, again, typically their light is augmented by LEDs under them!). BUT the tube filaments themselves do glow visibly in these rascals!
The one pictured above, albeit a bit blurrily, is actually at my house
This one was sold under the "Monoprice" brand. In the US, Parts Express still sells a variant thereof -- with higher advertised output power (the output section of these amps is solid state, despite the presence of two power output tubes on top!).
Home
Dayton Audio HTA100 Integrated Stereo Hybrid Tube Amplifier 100 WattsDayton Audio HTA100 Hybrid Tube AmplifierThe perfect solution to bring the rich sound of a tube amplifier to your home audio setup; the innovative design of the HTA100 combines the best of both worlds – the classic sound of...
www.parts-express.com
The drawback to these monstrosities (sold worldwide under many brand names): the tubes -- at least the two larger ones -- actually do get quite hot (i.e., they dissipate a fair amount of power), so they aren't quite benign.
Oooh. I just discovered that @amirm actually reviewed one of these.
Review and Measurements of Monoprice Hybrid Tube Amp
This is a review and detailed measurements of the Monoprice Hybrid Tube Power and Headphone Amplifier. It is on kind loan from a member who sent it to Monoprice to be fixed twice. It costs US $199 from Monoprice direct. I can't find it on Amazon but there is a "Rockville" amp that looks...
www.audiosciencereview.com
Here's the current listing of cheap tube junk available from Parts Express FWIW:
Count Arthur
Major Contributor
- Joined
- Jan 10, 2020
- Messages
- 2,252
- Likes
- 5,047
mhardy6647
Grand Contributor
- Joined
- Dec 12, 2019
- Messages
- 11,412
- Likes
- 24,773
Yeah, it's a pretty grim piece of hardware.
Out of the box, it also has that potpourri of chemical aromas that fairly shouts eau d'carcinogen to me!
But -- it is cheap!
Out of the box, it also has that potpourri of chemical aromas that fairly shouts eau d'carcinogen to me!
But -- it is cheap!
Anton D
Addicted to Fun and Learning
- Joined
- Mar 17, 2021
- Messages
- 863
- Likes
- 994
At which line on this graph does the 'good sound' start?
Here you go!
tubedepot.com
Taller Style Vacuum Tube Night Light
The smallest and best conversation piece in your home, recording studio and office is here! Newly improved and lower priced, the vacuum tube night light glows amber, blue or red (other colors may become available upon customer request). What more can you ask of a night light? The glow provides a
tubedepot.com
Galliardist
Major Contributor
You forgot the biscuit tin full of cartridges.
I remember being told at one hifi show, many years ago, that anybody serious had a biscuit tin full of cartridges, and anybody knowledgeable knew which eight of them were the same model rebadged...
mhardy6647
Grand Contributor
- Joined
- Dec 12, 2019
- Messages
- 11,412
- Likes
- 24,773
Galliardist
Major Contributor
I'm sure that qualifies.I have mine in a little wooden box, thank you very much.
I can hardly talk... I only have one pair of speakers, so I'm obviously not serious myself. Just keep that between us, I'd hate to ruin what little reputation I might have here
mhardy6647
Grand Contributor
- Joined
- Dec 12, 2019
- Messages
- 11,412
- Likes
- 24,773
I'm sure that qualifies.
I can hardly talk... I only have one pair of speakers, so I'm obviously not serious myself. Just keep that between us, I'd hate to ruin what little reputation I might have here
mhardy6647
Grand Contributor
- Joined
- Dec 12, 2019
- Messages
- 11,412
- Likes
- 24,773
Tubes 'n' racks go great together!
PS: the plate voltage on the 845 output triodes (only one of the two is visible) in this RCA amplifier is lethal, full stop*.
_________________
* With no pun intended, full stop.
LOL
Similar threads
