Little Bear Tube Phono Pre??

[T68]

I'm considering a LBT11 as my move from integrated preamp to external, and have a couple of questions I hope your can help me out with:

Will I notice any significant improvement compared to the built-in phono amp in a 45 years old integrated reciever?
My setup is: Dual 601 TT w. Dual20E cartridge/Jico stylus, Sonab 3000r amp and Boston Acoustics A60 speakers.

Are the hum issues with the t10 resolved in the t11?

Is it usable in its stock version? For me this is a pretty big buy so I won't be able to upgrade tubes and stuff the first year. So how good are the Chinese tubes that are submitted?

Are there any other better options for this money?

Thanks for any input on this!

 

[Lavane]

Mine has a bit of a hum when the gain control is cranked high. I use mine at just under half way. It also has a switch on the back that lets you disconnect earth ground. I did have a problem with it picking up a high pitched noise at first. It turned out if was coming from the refrigerator on the other side of the wall. But moving my equipment to the other side of the room got rid of it. You will want to use the metal tube shield on the far left tube. It's the most sensitive. Also you will want to replace the stock Chinese tubes with a better set of 12ax7's. So that's an added cost also. I couldn't say if it would sound better than what you have though. I think it sounds pretty good for the money. I'm using it in a second system since I now have a preamp with a phone built in.

 

[T68]

Thanks for your input, Lavane!
Seems as if I need room in the budget for some bett tubes if I get the Little Bear.

 

[Nixxuz]

I've got a T11 as well. I swapped cap for the PIOs and ran an internal wire from the ground plug to the shield base for the V1 tube. I use a metal shield on that tube and the V3 for aesthetics. Sounds great after those mods, (and, of course, a triad of Gold Lion 12AX7's).

 

[dave99]

I have the T11 also, and agree with the comments above. I did notice a change and difference in the soundstage with some pricey original 1959 Mullard 12AX7 tubes. I can't say it was worth the $$$, and listening to the Chinese, Russian and the Mullard's is very subjective as with any sound and who is listening. You can get some very good and very reasonably priced Russian tubes from the 50's and 60's on eBay that sound very close to the Mullards. Also ground that V1 tubes metal shield as it controls the hum very well. The Mullard's quieted the hum also one their own, but the shield helped more. I run the bias knob at about 70-75% and have no discernible hum, but will get hum if I crank all the way up. I haven't opened mine up so everything is all stock except for the tubes. I have it hooked up to a vintage Kenwood Basic amp and Basic C2 preamp through the CD connection, bypassing the phono section. Personally I like the T11.

I will add here the design is poor and awkward with the connections coming out of the front instead of the rear. It makes for a messy unprofessional installation. So you need to look at that issue as well if aesthetics is a concern.

 

[Lavane]

I have the T11 also, and agree with the comments above. I did notice a change and difference in the soundstage with some pricey original 1959 Mullard 12AX7 tubes. I can't say it was worth the $$$, and listening to the Chinese, Russian and the Mullard's is very subjective as with any sound and who is listening. You can get some very good and very reasonably priced Russian tubes from the 50's and 60's on eBay that sound very close to the Mullards. Also ground that V1 tubes metal shield as it controls the hum very well. The Mullard's quieted the hum also one their own, but the shield helped more. I run the bias knob at about 70-75% and have no discernible hum, but will get hum if I crank all the way up. I haven't opened mine up so everything is all stock except for the tubes. I have it hooked up to a vintage Kenwood Basic amp and Basic C2 preamp through the CD connection, bypassing the phono section. Personally I like the T11.

I will add here the design is poor and awkward with the connections coming out of the front instead of the rear. It makes for a messy unprofessional installation. So you need to look at that issue as well if aesthetics is a concern.

Using front connections = the shortet signal path. I have amplifiers with the inputs on the front as well. It can help in reducing noise.

 

[doug s.]

t10 vs t11?

hi! if i am willing to do typical modding tweaks for grounding & shielding (and maybe a few other things), wouldn't a t10 w/the toroid transformer be better than the t11 in this application, which uses an ei transformer?

thanks,

doug s.

 

[Lavane]

t10 vs t11?

hi! if i am willing to do typical modding tweaks for grounding & shielding (and maybe a few other things), wouldn't a t10 w/the toroid transformer be better than the t11 in this application, which uses an ei transformer?

thanks,

doug s.

The 11. Much less to mod compared to the 10. the dropping resistor for the 6.3v heaters, a simple resistor mod for the rectifier heater and your done. I didn't add any grounding to the tube shields since it wasn't needed. The heaters run hot in these. Dropping the heater voltage will add some life to the tubes.

 

[doug s.]

The 11. Much less to mod compared to the 10. the dropping resistor for the 6.3v heaters, a simple resistor mod for the rectifier heater and your done. I didn't add any grounding to the tube shields since it wasn't needed. The heaters run hot in these. Dropping the heater voltage will add some life to the tubes.

thanks for your comments. have you seen this one?

https://www.ebay.com/itm/272135536924

it has tube shields and a toroid. i can't help but think the toroid is a better transformer than what's in the t11. and then you could also do the resistor mods to it?

and, this looks like a worthwhile improvement; i suspect the latest t11 also has it:

re-design the Gain switch function. Before, it was through adjust output voltage to reduce output signal.and now. We through control V1 tube to setup Gain

thanks again,

doug s.

 

[Lavane]

I haven't seen that one. At leased the shields seem to be grounded. You would need to use a volt meter to check the heater voltages. Before doing anything. The transformers used in the earlier versions sold in the US used 110v primaries. So they run a bit hot. The specs for that one list 220-240 volt. I get very little hum from the T-11. I have to crank the level control pretty high to hear any. A long thread over at DIY covers many mods made to these. Most were replacing film capacitors along with changing a few values. I didn't get into any of that. It sounds fine like it is to me. You would want to get a set of 12ax7's to replace the Chinese 6n1's. The 6n1's sounded thin and were microphonic.

 

[rothwellaudio]

Using front connections = the shortet signal path. I have amplifiers with the inputs on the front as well. It can help in reducing noise.

The "shortest signal path" could be from the back if the unit is suitably designed. BTW, if low noise is the goal it would be a good idea not to have a mains transformer right next to the audio circuit board.

 

[T68]

Waiting for a Little Bear t10 2.5 that hopefully will arrive this week. After a really fast free shipping from Hongkong it's now up to Swedish mail and customs service.
I have a rule to never spend more than 100 dollars for any piece hifi gear so glad to find this for 90.
Looking forward to try, tinker and get to know tube audio.

 

[T68]

It's here! Swedish customs and import handling took their good time (two weeks after the shipment reached Swedish soil!). But now the LB t10 finally is playing nicely with my other gear (Dual 601, Shure M75 Jico elliptical, Sonab r3000 amp, Boston Acoustics A60).

Think bad shipping karma was made up by some shoppers luck: I received a 2.62 unit instead of the 2.5 I paid for!
So yes, some extra bells and whistles on this one like support for both 6n2 and 12ax7 valves (which I got), tube shields, gain switch and ground lift. Also got a complete acrylic box with closed sides.

I know I shall not judge audio before the valves settles a bit, but I already think it beats my previous riaa box (cheap Omega) and the internal in the Sonab by margin. No disturbing hum on my listening levels either, but might try the tube shields anyhow (but that transparent case and glowing valves sure look purty enough... ).

All and all very happy (but total tube noob so don't trust a word I write ;-) ) with this buy so far!

Here she glows!

 

[darg]

Out of the box with fresh tubes my unit sounded much better than what I had before and it just better over time. Only mod I did was to add a tubes hied to the input tube and put some copper wire on the bottom as kind like a ground mesh on the outside of the box as shielding which took care of the radio station I got at idle and from time to time

 

[T68]

Update: after spinning some vinyl through this thing I'm quite impressed with its performance!
Probably the most bang-for-the buck I have yet experienced in my humble setup (But those Boston Acoustics A60 I traded for a bottle of bourbon was a good deal too...).

Have already ordered a set of russian tubes to try out. Not that I hear anything wrong with the Chinese that was supplied but more for the fun of it.
Oh no beginning to realise that I've entered that slippery tube slope... .

 

[Devon Dancer]

I've been working my way through this thread (yes, really !!) whilst waiting for my LB to arrive from China. Well, it arrived yesterday and I thought I'd just add some initial impressions and some changes to the board since previous posts.
The packaging was excellent. very carefully packed with lots of foam inserts to keep things steady in transit so full marks for that (if thought has gone into that the rest can't be far behind !)
The version on the board was 2.62
Mine was supplied with a EI transformer not the toroidal. Thoughts on that? Time will tell.
All the transformer wiring had connectors ready installed with headers on the board. The mains input wiring used spade connectors the others standard computer board type headers, two-pin for the 15- and 6-volt wiring and a three pin for the 200V wiring. Made it very easy to wire up.
On firing up, the rectifier tube glowed at a level that would suggest voltage was spot on.
I haven't played anything through it yet but have connected to my amp and NO hum even at volume settings above my normal listening levels so fingers crossed.

Note to self....don't try to be too clever and think it would be a good idea to assemble the case before installing the board and definitely not with super glue! (luckily the glue idn't seem to work on the plastic anyway)

I'll come back once I've played some favourite vinyl through it.

 

[Lavane]

I've been working my way through this thread (yes, really !!) whilst waiting for my LB to arrive from China. Well, it arrived yesterday and I thought I'd just add some initial impressions and some changes to the board since previous posts.
The packaging was excellent. very carefully packed with lots of foam inserts to keep things steady in transit so full marks for that (if thought has gone into that the rest can't be far behind !)
The version on the board was 2.62
Mine was supplied with a EI transformer not the toroidal. Thoughts on that? Time will tell.
All the transformer wiring had connectors ready installed with headers on the board. The mains input wiring used spade connectors the others standard computer board type headers, two-pin for the 15- and 6-volt wiring and a three pin for the 200V wiring. Made it very easy to wire up.
On firing up, the rectifier tube glowed at a level that would suggest voltage was spot on.
I haven't played anything through it yet but have connected to my amp and NO hum even at volume settings above my normal listening levels so fingers crossed.

Note to self....don't try to be too clever and think it would be a good idea to assemble the case before installing the board and definitely not with super glue! (luckily the glue idn't seem to work on the plastic anyway)

I'll come back once I've played some favourite vinyl through it.

View attachment 1552813 View attachment 1552814 View attachment 1552815

What's the extra switch for next to the first input tube? The switch for each of the signal tubes is for switching between a 12ax7 and the Chinese tubes. But I see an extra one next to the one on the end.

 

[Nixxuz]

What's the extra switch for next to the first input tube? The switch for each of the signal tubes is for switching between a 12ax7 and the Chinese tubes. But I see an extra one next to the one on the end.

It's a gain switch. I assume if you have a lot of hum or whatnot you can switch it to try and alleviate that?

 

[Devon Dancer]

Correct !
The switch nearest the transformer mains input is to connect/disconnect the ground. There are three switches, one for each driver valve, for switching between 12AX7 and 6N2 valves and the switch nearest the phono sockets switches between high and low gain.

Incidentally, mine was supplied with 12AX7 valves.

 

[triode17]

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

You must give it time to break in the tubes and capacitors. New tube devices tend to sound a bit thin on the Bass and harsh in the Treble. I break in gear by a 2 hour listening session, then a full cool down ( in this case, at least a half hour). Repeat with another 2 hour session. After about 10-12 hours of running time, you should notice that the Bass has increased and the Treble has smoothed out.