Little bear tube Preamp T7 real tube amp or IC amp with glowing tubes for visual

Hi all

Just taken delivery of a Little Bear T7 Tube Preamp

One of the questions I had was is it a true tube amp or one of those low end chinese tube amps that are really IC amps and just use the tubes for visual effect.

The price from Douk was low enough for me to take a punt and see whats inside, the seller posted a picture of the populated circuit board that appeared to show that there where no IC's present so it should be a true tube amp, but is it

Pictures below

How it looks in all its splendor

http://i99.photobucket.com/albums/l3...psu09sd19x.jpg

Picture of the top of the PCB showing no IC's

http://i99.photobucket.com/albums/l3...psald0if4x.jpg

But wait, whats this underneath

http://i99.photobucket.com/albums/l3...pscjzafyq0.jpg

The 8 leg IC is a JRC2068 which is some form of OpAmp

http://www.datasheetcafe.com/jrc2068-datasheet-pdf/

So the question for those in the know, is is it a true tube amp or is that OpAmp really doing the amplification.

Thanks for any feedback

Paul

With a quick search it looks like the op-amp is the phono amplifier stage and the tubes are the 'valve buffer' stage after and for the AUX function.

:)

Quote:

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Originally Posted by Paul-H

So the question for those in the know, is is it a true tube amp or is that OpAmp really doing the amplification.

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What's a "true" tube amp? That's something that be debated endlessly. Some people scoff if there's a solid state rectifier in there instead of "true" tube rectifier. It all depends on how far you want to take the definition of "true tube".

Alan's assessment that the valves are acting as buffers sounds reasonable.

Quote:

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Originally Posted by RothwellAudio

Some people scoff if there's a solid state rectifier in there instead of "true" tube rectifier.

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As I said the other week. A rectifier just rectifies. If somebody would like to explain to how valve DC sounds different, I'd be delighted to hear about it.

What does using the tubes as a buffer achieve regarding the sound quality.

Been testing this unit today via an AB switch on my A-70 and to be honest I can't hear any difference.

Paul

Quote:

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Originally Posted by Paul-H

... to be honest I can't hear any difference.

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A buffer is supposed to be transparent. I'd be more worried if you could hear a difference than if you couldn't.

If you have an impedence mismatch between units then it should sort that. Some will impart a bit of a signature too. Some regard it as a warm valvy feel, but thats just imo smearing due to poor design and parts. As above you should reall only hear differences if your say, pre and power are a mismatch.. i use a very good one after my cd player, which seems to improve things since i upgraded it. Just seems to take an edge off the digital, so may be a problem, i dont know. Not complaining

Thanks for the explanation

Still not to sure why I bought it though as I was not dissatisfied with the phono stage in my old Pioneer A-70

Still it looks good in the dark and was quite cheap so no great loss, and also it's no worse so might be of use should I end up with more than one turntable, not that SHMBO will allow that, although she did give in and let me get a wall mount, so I must be wearing her down, it's only taken 30 years ;)

Paul