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Little bear tube Preamp T7

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Little bear tube Preamp T7

Postby Paul-H » 17 Mar 2017 19:54

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/l312/Paul-80/20170317_183950_zpsu09sd19x.jpg

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

http://i99.photobucket.com/albums/l312/Paul-80/20170317_183110_zpsald0if4x.jpg

But wait, whats this underneath

http://i99.photobucket.com/albums/l312/Paul-80/20170317_183122_zpscjzafyq0.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
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Re: Little bear tube Preamp T7

Postby Kurt45 » 17 Mar 2017 22:12

People who claim to know say "This is a hybrid, solid state op amp with tube buffer."
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Re: Little bear tube Preamp T7

Postby Erin1 » 20 Mar 2017 02:17

There is nothing wrong with op amps. Analogue audio is a perfect application for them. More important - How does this preamp sound?
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Re: Little bear tube Preamp T7

Postby Paul-H » 20 Mar 2017 11:32

How does it sound

I have only compared it to the built in Phono Stage in my Pioneer A-70 Amp (The 80's version) and to be honest I cannot hear any difference.

That might be because there is no difference or it might be that my heavy industry damaged hearing is not able to hear the difference. Got a couple of Mullard valves on the way to replace to supplied Chinese ones just to check.

Think I am starting to turn into an audiophool [-X

Paul
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Re: Little bear tube Preamp T7

Postby Erin1 » 20 Mar 2017 12:55

Paul-H wrote:How does it sound

I have only compared it to the built in Phono Stage in my Pioneer A-70 Amp (The 80's version) and to be honest I cannot hear any difference.

That might be because there is no difference or it might be that my heavy industry damaged hearing is not able to hear the difference. Got a couple of Mullard valves on the way to replace to supplied Chinese ones just to check.

Think I am starting to turn into an audiophool [-X

Paul


At least it doesn't sound worse.

An Audiophool would say the new thing sounds better. So I don't think you're in any danger of becoming one.
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Re: Little bear tube Preamp T7

Postby Erin1 » 20 Mar 2017 13:02

There are also transistors on the board in the middle. The black things with 3 legs.

I think the tubes look like an output buffer. They probably don't do any RIAA EQ.

You could probably bypass them and take the output straight off the transistors.
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Re: Little bear tube Preamp T7

Postby okitoki » 21 Mar 2017 04:24

i bought one from ebay last year...
seems pretty bight compare to my Vincent Pho8; tube rolled a few russian tubes I found around, and didnt seem to make much of a difference.

However, using it as a tube buffer made digital streaming from googlecast audio sounds more pleasing not as bright.

Biggest issue I had was the low hum I get when using as a phono preamp. But it does not appear on the aux input.

Sold it after a few months.
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Re: Little bear tube Preamp T7

Postby procyon81 » 17 Jun 2017 19:06

Hi, I'll write too much but please read.

I got the turntable from an old radio and separate it. I just kept the turntable engines of course and the line cables that come from the needle. I plugged that line directly to the input of a NAD receiver but the sound is too low. So reading in the internet I decided to buy a Little Bear T7.

So here's my personal review. The Aux In input doesn't do anything, it seems more like a bypass of the line signal.
If you switch to phono the signal is so high that becomes really noisy and overdriven. I put the gain switch that comes in the board to low but however is still too loud. Thinking that maybe the problem is in the phono I plugged a celphone to the phono input and tested the volume. Putting the phone volume to almost nothing the Little bear output is still loud and the sound quality is not good. So the problem is in the preamp. Also the sound has a very low frequency that makes my subwoffer sound almost permanently.

I don't recommend it to be honest. Now, I already have it and I'm not thinking just to throw it. I can't return it either.
Does anybody here has an idea how to modify the circuit to reduce the preamp gain?

Thanks,
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