Little Bear Tube Phono Pre??

[sled108]

Maybe...At least it's not the Culture Club...

 

[mhardy6647]

I think that's the second time today that I've seen you throw out a joke that didn't get any support...

Who knew AKers were so serious!?

Well... joke may be overstating things a bit...

 

[rnorton]

Anyone know if the input capacitance is set by a capacitor or by the cathode to grid capacitance of the input tube? I'm interested but 'd like to be able to knock the capacitance down to 100 pF if possible.

 

[Mid-Fi]

OK, looks like a good deal on paper but how about rollers? 5751 seems to be the upgrade and they are running ~$40 a piece. Other options?

 

[TankPopper]

From what i noticed, tube rolling is the main "problem" with this chinese units.. the tubes they use arent as versitile os others, but that is just my personal experience, i may be wrong.

 

[sled108]

This looks to me as being a 6DJ8 Pre... Having the Schematic would Help...What Ever it is Tho...You can Cut the Traces, and P to P wire it however you might want to...

 

[vinylkid58]

6N2P has the same heater wiring as 6922/6DJ8/6N1P etc., where pin #9 is a shield, not a heater center tap. The Russian tubes have a good rep., so I'd try them first before performing any major surgery.

jeff

 

[goldleaf]

A lot of the Chinese jobbies are lifted right off of US, German, Japanese and Korean diy forums. I traced the 12au7/FET little bear design/amp to an amateur in Korea (google Sijosae amp). Nothing wrong with that, just understand that as hobbyists they were looking for cheap but good and a lot of them used whatever surplus they had around which was often Soviet (and Chinese copies). BTW I own a Little Bear P-1 desktop headphone amp/pre (sounds much better w/8514 tubes), a portable B-1 CMoy-style headphone amp and a 6N3P preamp and they sound ok with my HifiMan HE400 cans and a Lepai 2020A (used as pre). Haven't tried the phono amp but their products are a reasonable value for money as are Indeed, Bravo and other similar vendors. My guess is that they are subbing the manufacture to the same guy(s) in ShenZhen.

Check out the nice ShenZhen diy heaven - like the old Akihabara! http://www.evilmadscientist.com/2009/a-visit-to-the-electronics-markets-of-shenzhen/

 

[sled108]

It would be Nice to see a Schematic of This...

 

[sled108]

Damn...Go Figure...They just added a Ground Post...

 

[TankPopper]

ok guys.. schematics are here!

they sent it without the values, so i hope we can figure out the basics of it at list.. once the unit is here i will be able the figure out the values and fill it up.

 

[krisjay]

There are many times these schematics do not match the actual amp, so don't be to shocked if it is a little off here and there. Many times the amps can vary from amp to amp.

 

[datafone]

Kris is correct, it would pay to trace the actual thing and compare.

For the price it looks interesting though, I would like to see a comparison of this and a EAR clone sold as a PCB only on that auction site.

 

[ScaleAutoArt]

I just pulled the trigger on one...currently using a DJpre on my main system and plan to move it to my office setup so this will be an interesting replacement.

And see they added a ground.

 

[sled108]

Here we Go...The Little Bear arrived on Mon...A week from China to the East Coast US, nice for Free Shipping...After attaching the Trans. wires and the Clear Plates it was ready to go. And, right out of the Box it worked Fine. I let it Burn In on Tues, and it Sounded Really Nice for the Price...But...It seemed a bit Bright. Not only in Tone, but also the Tubes themselves were Glowing Brightly. So, today I pulled the top cover and checked the Trans. Outputs for the Heaters...This has 2 Heater Windings, a 6.3v for the 6Z4, and a 15v that looks to be Rectified to 19v to Series feed the (3) 6N2's. Well, the 6.3v was 7.3v at the attachment block, and the 15v was 18v. No wonder they Glowed Brightly...So, I put 2 Parallel Diodes (In to Out) on 1 side of the 6Z4's block and got 6.3v., and on the 6N2 block I did the same for both Inputs and got 16.3v...I haven't checked them at the Socket Hot yet, but they look Much Better. There is another thing that I did that should be done on this. On a 6N2 the #9 pin is a Shield and should be Grounded...There is an open hole in the Ground Trace right between the Tubes that works well for this...So then, for you other Guys who are waiting for yours. Check the Tranny! The #9 pin can wait...Alrighty, I'm going to Turn Mine Up and do some Real Listening now...
P.S. What did I Say? Up went the Price of this...

 

[ScaleAutoArt]

Are you saying this no good out of the box ? I have one coming in a few days and didn't think it would require technical knowledge.:sigh:

 

[sled108]

This will work Fine out of the Box. You will have to cut the Wires from the Xformer and screw them into the Blocks...Do Not Cut These Short...Then, you will have to put the Tubes In. After that you just need to Attach the Upper and Lower Clear Plates...Depending on how it's Shipped, you might have to remove the Bottom Plate and the XFormer in order to Peel off the Paper from the Clear Plastic Plates...That can be Tricky...

 

[TankPopper]

mine should come in any day now.. i hope its going to be a good match with my newly acquired Lenco L78.

sled, any chance you can post some picture of the work you've done? im not that electronicly savvy and i want to make sure ill do it right (if it will be neccesary of course..)

 

[ScaleAutoArt]

Thanks Sled... I can do simple mods so I agree...if you can provide more detail

 

[sled108]

I'll post Pix on Friday...