New Little Bear Pro v2.5 breakdown

Phalanger, all I can is swap out for fancy parts. Im not an electric engineer and not taking advanced electronics courses in college. I just read 50% of Electronics 101 primer book and completed 3 "learning to solder" kits. Im comfortable soldering now with my nice new high end soldering station. That makes a world of differance.

i found out a few advanced things about capacitors and resistors from Google and Wikipedia. That helps. But no way can I change, correct or remake a circuit design.
 
Last, the only capacitor in the signal path that is normal shape is the 4700uF 35v cap. For some reason the schematic had it marked as "330pf Board Markings and 300Pf Stuffer" But on my Little Bear circuit board I have a single 4700uF 35v cap. Can anyone explain that?

The stock EAR834p, and all the modded schematics I've seen use a 330pf 1% cap, NOT 4700uf. With that value, the RIAA curve must be a mile off.

jeff
 
Im having trouble finding a quality 4700uF 35v capacitor. I assume all these capacitors I listed above are film caps? The electalic caps are all in the power supply section only?

Also I just finished reading this long thread on Line Workers vs R&D engineers lol
http://www.audiokarma.org/forums/archive/index.php/t-381961.html

4700uF cap is unlikely to be anything else than electrolytic; electrolytics are the only type that can (practically) hold that much capacitance.
This would be a good candidate to replace with a Blackgate. Other alternatives would be Elna Silmic, Nichicon Muse, etc.
 
The 330pF caps are marked on the board as 331. The vendors schematic seems to indicate that the actual value fitted was 300pF, probably to fine tweak the RIAA curves. You don't want to fit a 470uF in there!
 

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Photos of the two electrolytic caps 4700uF 35v. but the circuit board shows 3300uF 50v. but there is aa 4700uF 35v is socketed there instead. This confused me. Parts Connexion does have other 4700uF 35v or 50v besides what is already installed. (what is a "snap in"?) (How do I solder in a 4 pole and what is it for?)

MUNDORF-71837 4700µF / 63VDC, MLytic® Audio Grade, MLGO (Glue-On 2Pin), 30
MUNDORF-71841 4700µF / 40VDC, MLytic® Audio Grade, MLGO (Glue-On 2Pin),
JENSEN-71019 4700uf / 63V, 4 - pole, 35mmD x 30mmL
NICHICON-74643 4700uF / 50VDC, FW Series, 20mmD x 40mmH
NICHICON-73623 4700uF / 63VDC, KG Series, Gold Tune, 25mmD x 50mmH, Snap-in,
JENSEN-78829 4700uf / 63V, Radial - Single, snap-in, 35mmD x 50mmL, Solder Lug
JENSEN-78836 4700uf / 63V, Radial - Single, ESR at 100Hz 48 mOhm, Snap-in, 35mmD x...
JENSEN-78841 4700uf / 100V, Radial - Single, ESR at 100Hz 70 mOhm, Snap-in, 40mmD
MUNDORF-75211 4700µF / 100VDC, Mlytic AG+, MLGO+ (Glue-On, 4Pin), 4-Pole, Electrolytic C

Parts Connexion also sells the 3300uF as read on the circuit board:
NICHICON-72619 FW series 3300uF 50v
MUNDORF-71836 3300µF / 63VDC, MLytic® Audio Grade, MLGO (Glue-On 2Pin), 30mmD
JENSEN-71021 3300uf / 100V, 4 - pole, 35mmD x 40mmL
MUNDORF-75210 3300µF / 100VDC, Mlytic AG+, MLGO+ (Glue-On, 4Pin), 4-Pole, Ele


Ok I must have read the drawing incorrectly. I see that 330pF caps are marked on the board as 331 are those round ceramic caps that I had no intention of replacing. I never read any comments on any forum that people upgrade these kind of caps. If they can be upgraded for better sound quality what would I replace them with? Other ceramic round caps or a differant kind of film cap?
 

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Photos of the two electrolytic caps 4700uF 35v. but the circuit board shows 3300uF 50v. but there is aa 4700uF 35v is socketed there instead. This confused me. Parts Connexion does have other 4700uF 35v or 50v besides what is already installed. (what is a "snap in"?) (How do I solder in a 4 pole and what is it for?)

MUNDORF-71837 4700µF / 63VDC, MLytic® Audio Grade, MLGO (Glue-On 2Pin), 30
MUNDORF-71841 4700µF / 40VDC, MLytic® Audio Grade, MLGO (Glue-On 2Pin),
JENSEN-71019 4700uf / 63V, 4 - pole, 35mmD x 30mmL
NICHICON-74643 4700uF / 50VDC, FW Series, 20mmD x 40mmH
NICHICON-73623 4700uF / 63VDC, KG Series, Gold Tune, 25mmD x 50mmH, Snap-in,
JENSEN-78829 4700uf / 63V, Radial - Single, snap-in, 35mmD x 50mmL, Solder Lug
JENSEN-78836 4700uf / 63V, Radial - Single, ESR at 100Hz 48 mOhm, Snap-in, 35mmD x...
JENSEN-78841 4700uf / 100V, Radial - Single, ESR at 100Hz 70 mOhm, Snap-in, 40mmD
MUNDORF-75211 4700µF / 100VDC, Mlytic AG+, MLGO+ (Glue-On, 4Pin), 4-Pole, Electrolytic C

Parts Connexion also sells the 3300uF as read on the circuit board:
NICHICON-72619 FW series 3300uF 50v
MUNDORF-71836 3300µF / 63VDC, MLytic® Audio Grade, MLGO (Glue-On 2Pin), 30mmD
JENSEN-71021 3300uf / 100V, 4 - pole, 35mmD x 40mmL
MUNDORF-75210 3300µF / 100VDC, Mlytic AG+, MLGO+ (Glue-On, 4Pin), 4-Pole, Ele


Ok I must have read the drawing incorrectly. I see that 330pF caps are marked on the board as 331 are those round ceramic caps that I had no intention of replacing. I never read any comments on any forum that people upgrade these kind of caps. If they can be upgraded for better sound quality what would I replace them with? Other ceramic round caps or a differant kind of film cap?

You could replace the ceramics with either tantalum caps or better ceramics.
 
Ok, I figured out what a 4pole is but have no idea how to replace a normal cap with it so im not going to bother with those. Snap In caps i looked up on Wikipedia and know what those are now. So I can use those.

Parts Connexion does not have a way to search by Ceramic or "Pearl" tantalum caps. So dont know what they have. I guess I can reverse look up by going to the Mundorf website, find the part number, then search by part number on Parts Connexion.

I still never found out why the Little Bear circuit board shows 3300uF 50v but they used 4700uF 35v instead. I will take a close up photo tonight to show that specifically.
 
I still never found out why the Little Bear circuit board shows 3300uF 50v but they used 4700uF 35v instead. I will take a close up photo tonight to show that specifically.

The 35v caps are cheaper.:yes: Those caps are most likely for the CRC section, right after the diode in the heater supply secondary.

jeff
 
I understand the reason about the voltage. But why is the uF differant? Here is a better photo.

So, if I replace the two 4700uF 35v caps with something much better quality what values do I use?
4700uF or 3300uF. I dont understand why the circuit board shows one uF value and the caps are another. I thought that was one thing you do not change?
 

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Finally received my Russian rectifier tubes from Russia . I got 4 for the price of one so at least if one is weak, wears out or explodes I don't have to place another order and wait 6 weeks from Russia.

First off, these Russian tubes are taller than the cheap chinese tubes that come with the Little Bear phono preamp. I compared them side by side and noticed that the physical metal structure inside the tube is more robust.

When I plugged the tube in and turned on the phono preamp to warm up I noticed that the tube does not glow as bright as the chinese tube. I remember comments from others on differant threads asking why is that chinese rectifier tube so bright. Well, this russian tube is as bright a glow as the 12ax7 Telefunkens I have plugged in.

First thing I noticed about the differance in sound is how much more headroom, power and responsive dynamics. I didnt A/B the tubes (I hardly ever do that) so I couldnt tell if there was any better sound quality besides the improved power and dynamics. If it was cleaner, less grain, bigger sound stage I didn't hear much of a differance. It could be there but the increased power envelope and dynamics held my attention. Either way, a definate improvement over the stock chinese tubes and a no brainer upgrade for $10.
 

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Finally received my Russian rectifier tubes from Russia . I got 4 for the price of one so at least if one is weak, wears out or explodes I don't have to place another order and wait 6 weeks from Russia.

First off, these Russian tubes are taller than the cheap chinese tubes that come with the Little Bear phono preamp. I compared them side by side and noticed that the physical metal structure inside the tube is more robust.

When I plugged the tube in and turned on the phono preamp to warm up I noticed that the tube does not glow as bright as the chinese tube. I remember comments from others on differant threads asking why is that chinese rectifier tube so bright. Well, this russian tube is as bright a glow as the 12ax7 Telefunkens I have plugged in.

First thing I noticed about the differance in sound is how much more headroom, power and responsive dynamics. I didnt A/B the tubes (I hardly ever do that) so I couldnt tell if there was any better sound quality besides the improved power and dynamics. If it was cleaner, less grain, bigger sound stage I didn't hear much of a differance. It could be there but the increased power envelope and dynamics held my attention. Either way, a definate improvement over the stock chinese tubes and a no brainer upgrade for $10.

:thmbsp: where I can find those? what brand?
 
There was only two sellers from Russia selling these. I picked one that had less of a shipping time.

4x 6C4P-EV / EZ90 / 6Z31 rectifier Refelctor Tubes
alexer1 (25697) 100% positive feedback
 
There was only two sellers from Russia selling these. I picked one that had less of a shipping time.

4x 6C4P-EV / EZ90 / 6Z31 rectifier Refelctor Tubes
alexer1 (25697) 100% positive feedback

Thanks!
My LB is all stock, will I get any improvement out of these?
What 12AX7 tubes you upgraded to?
 
Yes, there is defiantly a shift of sound signatures from the Fisher labeled Telefunken 12ax7 tubes I got off ebay for cheap. Also, there is definitely stronger, deeper, wider and dynamic bass and mid bass with the telefunken tubes. They are also smoother and bigger sounding with layered and textured detail. The Chinese tubes seemed more dynamic up top.

My next choice was to buy the 3 pack of Gold Lions but I found the telefunkens for $20 less on ebay. They tested strong 77/77

I done know anything about the 5750 tubes...

I alo added Pangea feet, power cable ac14se.
Herbie tube dampers. All made a big improvement
 
Hey, I got an answer to my question about the two 4700uF capacitors from the manufacturer in china. See what 3 exciting news he is working on! He gonna dominate the market !
BTW, the LittleBear manaufacturer read this thread. He also told me in a 2nd email that he thinks I will get better sound quality if I drop this Little Bear into a metal case. hmmm

Dear stylinlp,

that's both 4700uf just for the power to 3x 12ax7 tube lightting. it's work for regulators.
you also can use 3300uf. no problem. but it's can not make huge sound effect.
current we're in design a new version. it's maybe take about 2 months to finished. for make a better voltage output.and maybe add MC version.

- wfqxgw
 
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Hey, I got an answer to my question about the two 4700uF capacitors from the manufacturer in china. See what 3 exciting news he is working on! He gonna dominate the market !
BTW, the LittleBear manaufacturer read this thread. He also told me in a 2nd email that he thinks I will get better sound quality if I drop this Little Bear into a metal case. hmmm

metal case as conductive or non-conductive?
 
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