Little Bear t10 v2.5 Preamp quality upgrade so far

I forgot to ask what you did here exactly. I can see that you grounded out the shield which is what I read was required for a proper shield. My rectifier is the only one making noise now I believe. The 12ax7a tubes are near silent and sound awesome

 

Took bottom of tin foil take out tray and cut it into a strip, wrapped it around the tube and used electrical tape to keep the shape and hold the copper speaker wire against it. Other end of the speaker wire attached to the ground of the LB. There is a noticeable difference when you put this on that tube. I have not tried shielding other tubes but I believe others have tried and not found any difference, its just that first tube.

 

Way cool good to know. I'll test this out soon

 

I have a Little Bear tube headphone amp that I purchased a few years ago (not sure of the model #) It has an external power supply, yet this model also has the hum. Never really bothered to investigate a fix as I originally purchased it only for the purpose of identifying noisy / microphonic tubes.

 

Hi guys.

Sorry to hijack here

Was just reading along as am keen to get a Little Bear. I wanted to see what thoughts are on the difference between 'Little Bear T10 Pro 12AX7' and HN 'Little Bear T10 Pro 6N2' . So, basically - Toroidal + 6N2 ..or.. EI Transformer + 12AX7.

Any thoughts greatly appreciated

 

I went with the toroidal transformer and 6N2 tubes. I dislike the tubes that came with it. I went ahead and flipped all the switches over to 12ax7 and put some nice tubes in it.

 

and I did craft a shield for the rear tube right near the RCA inputs. it is a very noisy spot and needs shielding. I used a Pabst can that I cut into strips to make a shield and ran a wire from it to the main ground

 

Hey guys . I got the T10 2.5 Toroidal with the OEM 6n2 tubes about 6 months ago and have been posting on the massive thread over at vinylengine. A lot of the comments over at VinylEngine are prob excellent advice but I don't understand electronics enough to understand a lot of them, (and they date right back to version 2.2).
This is my first tube anything because I didn't grow up with them, they're often expensive and a total mystery to me. 'Tube Rolling' looks like the sky is the limit like all the other 'stereo stuff' we discuss but it's easy enough for me to do at the cheap level. I can see it's pretty much a never ending story with infinite impressions, cos all the tubes are different as well as our gearing and hearing.
I was looking for somewhere to discuss our LB tube rolling experiences and I ended up here on 'The Hoff'("man")" where I post anyway so maybe we can chat about that here.

Enough of the intro. Firstly the Rectifier. I ordered some old Russian ones just for spares. Just because I had them I put one into the LB and it was a big and noticeable improvement. As you mentioned, people say it shouldn't make any difference because it's not in the signal path, but it did. The rational explanation is that it was just a better made tube. I don't have a tube tester to tell, just my ears.

I'll be back with more comments later and suspect I might be talking to myself a bit, but what the hell.

 

E.Baba Your right about the rectifier not being in the signal path. However, the rectifier will effect every tube in the signal path by supplying it with more or less volts. Your rectifier is changing your AC volts to DC volts. One rectifier can product more or less volts then another which can make a huge impact to some equipment. Case in point, my Mapleshade Audio modified HH Scott LK-48. All tube amp that is suppose to use a 5AR4/GZ34 rectifier. I have a number of high dollar GZ34's (Mullard $100....ouch) for it but I use a Phillips 5R4GYS rectifier. The 5R4GYS produces less volts, so the unit does not have its full wattage. The trade off is pure sweet music. Liquid, is the best way to describe it. The first tube you should be changing, is the rectifier. Also, anyone using the stock China tubes and thinks it sounds good.......get rid of those things. I have not heard one China tube that sounds good compared to even a cheap NOS GE, RCA and the like. Also those China tubes are noisy. That's probably where most of your hum is coming from that so many people complain about. I have a Dark Voice 336se and a Little Bear P8 metal. Both came with China tubes that hummed and just sounded so sloppy. Both units improved substantially with NOS USA and Euro (mullard, telefunken, amperex...ect) tubes.

Been thinking about getting one of these T10 2.5 ver. That 6Z4 rectifier concerns me though. Has anyone tried the tube adapter for 6Z4 to 6X4?
http://www.ebay.com/itm/281787184165?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT

Iv used these adapters in my Dark Voice to swap the 6SN7 to a 12AU7. Huge improvement. You have so many more options with the 6X4 (RCA, GE the list goes on)
http://www.ebay.com/itm/201503161431?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT

 

This is the rectifier http://www.ebay.com/itm/2x-6C4P-V-EZ90-6X4-tubes-1960x-NIB-NOS-OTK-/221995279495?
I used and this is the vinylengine discussion as to why they have different numbers but are the same drop in without adapter needed; if you can follow the logic. http://www.vinylengine.com/turntable_forum/viewtopic.php?f=19&t=67059&start=825

 

That's weird. On Ebay they advertise it as a 6X4/EZ90 but with a different pin out. Direct drop in for 6Z4. That means it is a 6Z4 and NOT a 6X4/EZ90. I haven't had much experience with the 6Z4/6X4 but from my understanding the difference between them are a few pins. Exactly like there describing this USSR tube as. To run a 6X4 you have to either rewire a couple of pins or use an adapter. They even said in the form that its not a 6X4 but in fact a Russian version of the china 6Z4.

There's no doubt in my mind that this Russian NOS tube would be leaps and bounds over the china crap that came with it. I want to know if someone has used an actual 6X4 with an adapter or by rewiring there 6Z4 socket. NOS USA RCA black plates are a very sweet tube and are available in a 6X4. I would love to run one of these in the LB T10 along with some Amperx or Tele 12AX7's.

Has anyone tried putting the power supply in a separate box to make it an external power supply? Parts Express has everything you need for this. If I end up ordering one I would end up doing that right off the bat.

Thanks for the links E.baba

 

That's right. on Ebay it says 6x4 but directly dropped in for 6z4 so it is a 6z4 ? I am a complete Tube Nube thus my tight questioning on the vinylEngine thread. (which I still couldn't explain fully), and why I linked that for you.

It was directly and obviously better. I have a couple of spares.

I dare say on 'earth' where you are there are more tubes available than in 'the valley of Oz' where I am and your budget sounds bigger. NOS is usually out of my budget. I have a single old GB Mullard supposed to be on the way in the post but only have a Russian Tung Sol 12ax7 and a Chinese Shuguang 12ax7B to go with it.

There have been some custom boxes made and at least one I have seen did move the power supply away from the board as far as the original wiring would allow. I doubt there's even a Parts Express in the country here. For a 'first world' nation we seem to be lacking in the most simple availability of things.....or maybe just in this obscure valley where there's not even TV.

 

I found I prefer the Gain turned to Low. From my readings the original model just had very high gain which caused distortion problems so the Gain switch was put in to allow it to turn down; which might be why I prefer it Low anyway. High might just be too high.

For access to the Gain I drilled a hole above it the same size as the holes to access the tube swap switches. (Put masking tape down first so the drill stays where you put it). Looks factory. I see the new 2.6 has cooling holes above the power supply. I might drill some in my 2.5 later. As it is I run mine with the top off too cos I'm still playing with the tubes.

 

How's that pre holding up against that in your good old solid state Sansui ?

 

I have since upgraded my friend. The little bear has been put away until I build another setup. I ended up purchasing a beauty of an amplifier, and tucked all my other stuff away. I am using this Mac 4100 now

 

I got the switchable V2.5 with Chinese OEM 6n2 and as suggested around the place bought the Russian 6n2. I got the heavy duty long life ones. Initially they introduced a 'hardness' in the mid upper that was too much for me. Eventually I put a Russian one in V2 only which is the main position to change the sound and it was superior all 'round. I've got the Russian 6n2 in V1 and V2 now and it sounds superior. I'll get to experimenting with a Russian 6n2 in the V3 (so that's all of them) at some point.
Running a LB SUT T8-1 does, at least initially, add some sharpness to the topend.

Haven't tried any 12ax7/ECC83 yet. I have an old G.B. Mullard coming for the V2 position to be supported by more recent 12ax7s in V1 and V3. I have read opinion either way as to whether the 6n2 or 12ax7 range will be better so , as usual, it will be check it out for myself as far as the (limited) budget allows.

 

Update: I left the V3 OEM 6n2 for a couple of sessions merely because as a 'follower' I didn't expect much. Still I was hearing some 'graininess' so I put a Russian in V3; and was really surprised. The clarity !! Superb. Finished what the others had started. In simple terms what was wrong with my dismissing it as less important as 'just a follower' and why did it make such a big difference ? thanks.

(Old G.B. Mullard still not here to start with the 12ax7s)

 

I've been eyeing these LB's for quite some time now and have found it interesting to watch the iterations progress. At first, I was going to rewire for 12AX7's, then they took care of that. Toroidal xformer, check. I like the idea of that added gain switch as well, check. Glad I've refrained because I think I'm going to pull the trigger on the most recent offering from Douk. They claim it's silent.

Nobsound NS-10G Pro 6N2 Tube Phono Preamplifier MM Turntables RIAA HiFi Pre-Amp »

 

That 'Little Bear' you linked does not say 'Little Bear' on it anywhere. Also to my untrained eye it looks like a 2.5 not the latest 2.6. I have started a thread here asking about the various same looking things called different names. Little Bear/Douk/ Nobsound What's the connection ? - Vinyl Engine »

 

If you read on in the auction verbage, they explain that this is the Little Bear T10 latest "upgrated" version (lol) in a metal enclosure. Since Douk also sells the others with LB printed on them, I tend to believe it.

I studied the top photos of both the 2.6 and this version and aside from the shields, can't find a discernible difference. Could you maybe point out what difference you are noticing?

As I was getting poised to buy a V2.6 from Douk about a month or two ago, I noticed they included in the auction ad that an enclosure was going to be available for them soon. So I waited. This is probably what they were talking about.

 

Sorry I'm not able to tell anything else just by looking at it. I know they changed how the Gain works but I don't know if the Gain switch itself is the same place or what.
Just saying "Latest upgrated" doesn't mean anything to me without an actual model number.

And like I said over at Vinyl Engine someone did link a thing being sold that is the same internals in a box and called a 'Philharmonic'.
I started the thread over at vinyl engine *asking* if anyone knows what's going on since there's people there who tear them apart and are a lot more familiar with them than me.
The seller I use on ebay 'woshixionghui2010' only sells Little Bear stuff not an array of gear from elsewhere.

It could be a 2.5 in a box or a 2.6 in a box but it says Nobsound on it. I reckon it's a Bear in a Box and the box is a Nobsound addition.
It looks like you're paying a bit more for a box, and for all I know with all that box around it it could be earthed really well and work even better.

 

I am hoping so.

Will post pics of the underside of PCB for comparison when it arrives.

 

Can people familiar with the Little Bear T10 help me out? I've assembled it but it won't turn on. I've redone the wires twice and changed around the tubes but nothing happens.

 

Don't mind me, the power cable was shot and replacing it fixed the problem.

 

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