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Input on a tube (valve) 1 watt stereo audio amp

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mramos1

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A friend of mine saw a Zvex IMPAMP, a 1 watt stereo tube audio amp. He likes high tech and old tech. He wants to use it for his ipod in the office.:)

The impamp is $700+ I searched and found some kits. Might go for the $157 8 watt one and redo the PCB.. I found nothing close, but thought I would ask here.

He wants 1-8 watt range as long as it has a "small" foot print (ipod size).. Any idea for locations of something like that under $200. His birthday is at the end of the month and I would like to buy/build a kit or make PCB and build it..

Audioguru?? Or too young for tubes:D
 
Valves and 'small footprint' don't go together - why not build a better quality transistor or IC amp?, the recent enthusiasm for buying or building expensive valve amps completely escapes me?.
 
No, he has to have tubes in it and small. He wants the latest MP3 player in the old style AMP... The impamp was sort of neat. Only 1 watt though.
 
mramos1 said:
Audioguru?? Or too young for tubes:D
I grew up with vacuum tubes and made my last tube amp about 45 years ago.
Tube amps are very distorted when compared to modern amps. The operating conditions of the tubes deteriorate with age causing the distortion to increase even more.
Some modern very expensive amps are solid state but use a tube or two not connected but just glowing for show.
 
Some modern very expensive amps are solid state but use a tube or two not connected but just glowing for show.
Now there is a good idea, and you only have to provide 6 or 12 volts to run the filaments, rather than 250-350 volt DC power supply, with a big honkin transformer.
 
BeeBop said:
Now there is a good idea, and you only have to provide 6 or 12 volts to run the filaments, rather than 250-350 volt DC power supply, with a big honkin transformer.
The power supply also makes the high voltage for the tubes to glow purple inside from fluorescence. But I haven't seen any with their plates red-hot.
 
The power supply also makes the high voltage for the tubes to glow purple inside from fluorescence. But I haven't seen any with their plates red-hot.
So then just powering the filaments wouldn't give the effect? It has been a long time since I have seen a tube powered up, but I do remember that magic glow.
 
Get a Hammond 1590 series cast aluminum case, 2 cheap closed case transformers, a pair of any tubes, and a pair of sockets for the tubes. Use one transformer to power the heaters in the tubes, the other to power a single chip amplifer circuit inside the box. End result, it will look just like the IMPAMP.

You get the best of both worlds, retro looking space heater, and decent audio.

I thought that the purple glow was the sign of ionization & impending death in virtually all vacuum tubes. OK, maybe HV rectifiers, and some specialty tubes, but mostly it meant a trip to the tube drawer.
 
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audioguru said:
I grew up with vacuum tubes and made my last tube amp about 45 years ago.
Tube amps are very distorted when compared to modern amps. The operating conditions of the tubes deteriorate with age causing the distortion to increase even more.
Some modern very expensive amps are solid state but use a tube or two not connected but just glowing for show.

That is the effect he is after. Maybe I will look that way.. It is the old look, glowing tubes and size.. Maybe the bottom of the board has the real solid state amp. :)
 
zevon8 said:
Get a Hammond 1590 series cast aluminum case, 2 cheap closed case transformers, a pair of any tubes, and a pair of sockets for the tubes. Use one transformer to power the heaters in the tubes, the other to power a single chip amplifer circuit inside the box. End result, it will look just like the IMPAMP.

You get the best of both worlds, retro looking space heater, and decent audio.
That sounds great. But I guess no one has done this yet... Gonna go look at the Hammond 1590 case. See if it is small.

Thanks
 
I will run that by him, but bet he will like that idea better. So I just hook on transformer (via resistor?) to the tube. That will light them? And I would just get a small audio amp and run it off the other transformer.
 
Tubes are very expensive and using them purely for aesthetic purposes seems a waste of money to me. Some people (mainly guitarists) use tube amps for their distortion. I don't know how easy it is to emulate using solid state devices.
 
Hero999 said:
Tubes are very expensive and using them purely for aesthetic purposes seems a waste of money to me.
Don't you think the $700.00 for a 1W tube amp is a waste of money?
 
Audio Guru, yes $700 is, why we are looking to build one. I think zevon8 has the right idea. Maybe I can find an old TV for the tubes and sockets.. Or an old radio at a yard sale.. :)
 
Yeah, that is a good idea to source cheap tubes. For the actual amplifier, you might consider TDA2030AV chips, i've used them in a stereo amplifier connected to £300 worth of speakers and they do a very good job. 18W maximum output each.
 
I found a $19.95 10w x 10w hifi stereo audio amp kit. With a TDA chip Dr.EM.

And the board is small 3x1.5x1.5 range. I think I will get that and hide it in the case.

It has screw down terminals, so I can put old knobs on it and run wires to the board. Drill out the case for the input and outputs and power. Looks like I can bend the TDA chip flat with the board as well and get more room.

Need to get a cheap source for a pairs of sockets and tubes and figure out how to light them up.. I have some dual pots around, whould be slick to have the tubes brighten when the volume is turned up.
 
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