Little Bear Tube Phono Pre??

[rowingcoach]

I am thinking of getting this cool looking Preamp. I have read the thread back to front a couple times. I understand the Diode upgrade so have those in my cart. Along with my (currently in the shop sx-1010) I have a nice little Musical Paradise mp301 as my second system. This preamp might be a good way to use my turntable!

I am confused by the talk about WIMA and PIO. WIMA is a manufactur according to google? PIOS are an old type of Cap akin to newer types? Those are just basic bipolar caps? Or are they something else? Based on what you are all saying I should switch out the 6 caps? Are these Russian vintage green ones really that good? Or should I get some of these?....

2 each Audyn Cap Q4 0.1uF 400V MKP Metalized Polypropylene Foil Crossover Capacitor

• Features tightly wound MKP metalized polypropylene foil
  Designed for super-low microphonics
  Low loss of 0.0003% @ 1 kHz/20°C
  400 VDC voltage rating
  Precision made in Germany with 5% tolerance

4 each Jantzen 0.47uF 800V Z-Superior Capacitor

• Rated: <0.33 uF @ 800 VDC, >0.47 uF @ 1200 VDC • Tolerance: 2% • Value: 0.47 uF • Dimensions: 16 mm Dia. x 43 mm L.

Are those "good" sounding? Or overkill? Or should i stick with the "vintage russians"

Thanks people!

AC

 

[davek65]

PIA hum

Have Preamp connected to Bucking box for line voltage drop . But can't get
rid of the hum . Mostly in right channel . Tried Reversing polarity , Lifting ground . Re-soldered all connections on PC board . Using Russian tubes .
Did the 9 pin grounding . Going to do the board shielding next . Going to
try relocating to a different spot . This preamp has a lot of gain in my
setup . Pretty loud at the 9 o'clock position when playing vinyl at 3 mv
input . Don't know what to do after that .!!!!???:scratch2:

 

[Cobra2]

Extend all leads from trafo, and make some distance to PCB...

Arne K

 

[Cicaro]

I am thinking of getting this cool looking Preamp. I have read the thread back to front a couple times. I understand the Diode upgrade so have those in my cart. Along with my (currently in the shop sx-1010) I have a nice little Musical Paradise mp301 as my second system. This preamp might be a good way to use my turntable!

I am confused by the talk about WIMA and PIO. WIMA is a manufactur according to google? PIOS are an old type of Cap akin to newer types? Those are just basic bipolar caps? Or are they something else? Based on what you are all saying I should switch out the 6 caps? Are these Russian vintage green ones really that good? Or should I get some of these?....

2 each Audyn Cap Q4 0.1uF 400V MKP Metalized Polypropylene Foil Crossover Capacitor

• Features tightly wound MKP metalized polypropylene foil
  Designed for super-low microphonics
  Low loss of 0.0003% @ 1 kHz/20°C
  400 VDC voltage rating
  Precision made in Germany with 5% tolerance

4 each Jantzen 0.47uF 800V Z-Superior Capacitor

• Rated: <0.33 uF @ 800 VDC, >0.47 uF @ 1200 VDC • Tolerance: 2% • Value: 0.47 uF • Dimensions: 16 mm Dia. x 43 mm L.

Are those "good" sounding? Or overkill? Or should i stick with the "vintage russians"

Thanks people!

AC

I don't know anything about those Jantzen and Audyn, but I have russianmade PIO:s on the way so I'll try to give some type of subjective review of them at least when they arrive

I bought these, the links given earlier in the thread wouldn't ship to sweden:
http://www.ebay.com/itm/201037986286?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
http://www.ebay.com/itm/380844511036?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

 

[rowingcoach]

I ordered the caps that I posted about. Worst case I can always replace them again if they are noisy.

 

[Jimerson]

Yesterday I pulled my ADS 1230's out. I'd never been happy with these, they always sounded thin compared to my JBL's (L200b with 2405's). I ran the LB between my Dynaco MKIII's and my Vincent pre and it sounded amazing. Everything was all there and balanced. They have never sounded better, and I see what the ADS hype is about now. It's amazing when you find the right chain of gear to produce a certain sound in a certain area. I had been planning on selling the ADS's, but with the addition of a $110 pre they are now keepers!

 

[iaregenius]

Why do the diodes running to the 6.3V look so much smaller look so much smaller than the other diodes? in the Schematic they appear to be the same.

 

[ScaleAutoArt]

I am getting noise out of the left channel...I guess it's "tube rush"...it sounds like wind that is erratic. Any guidance on where to start looking?

It's only above the 9 o'clock position on my volume.

 

[sled108]

That sounds Tube Related...Try wiggling each one from the top with your Finger Tip while closely listening for a change in the sound.

 

[rowingcoach]

Got the Bear and the caps. Installed them and started playing the amp through my budget tube amp (Musical Paradise MP301). It is very nice indeed. The only noise I hear now is the faint rumble of the turntable motor. I have DUAL 1225.

When I first turned it on I had a terrible buzz. The Little Bear was on top of a Denon SACD player. Once i put the Lil'Bear on the plain surface of the table the buzz went away.

I am wondering about the Tubes and the brightness of them. How do I know if my transformer is overpowering? Can I add those Diodes anyhow and just hope they get it close enough?

 

[brijenjas]

I am wondering about the Tubes and the brightness of them. How do I know if my transformer is overpowering? Can I add those Diodes anyhow and just hope they get it close enough?

Measure with a DMM set on volts A/C.

 

[technocrati]

Could you explain exactly where i should mesure voltage points? im very confused on measuring ac voltage on the board. Thanks you

 

[brijenjas]

Could you explain exactly where i should mesure voltage points? im very confused on measuring ac voltage on the board. Thanks you

DMM set o VAC.

With the transformer installed and unit turned on (be very careful with live electric circuit!), measure across the terminals at the 15Vconnector block and the 6.3V connector.
Since you are measuring AC voltage the red and black connections can be reversed.

 

[rowingcoach]

I would like to amend my earlier post about there being buzz....

There IS no buzz. AT ALL.

I replaced all the main caps with fancy Jatsen and Audyn caps.

The buzz I was hearing was my Plasma TV being ON and too close to the tube amp and tube power amp. DUH. Stupid me.

Both amps are now placed on top of my Denon SACD player and working great attached to my Dual 1225. NO buzz, no hiss. no rumble. I can NOT hear any motor rumble at all.

I also replaced all my audio cables with high quality ones.

I would review the Little Bear very highly. It is easy to modify, looks snazzy, but best of all the PRICE WAS RIGHT. I have never heard my records this way, EVER!

 

[kirkmartin]

Hey Sled,
I know this is an old post, but I have been following and doing the mods. to the LB phono stage and I have a question for you.
When my LB arrived I cked the PT voltage and it was 19.84 on the 15v side and 7.85 on the 6v side, I added the diodes as per your diagram and now the 15v is 17.60 and the 6v is 6.83 is that low enough ? I don't recall seeing your after mod readings, should I add more diode or will it be ok ?
Thanks,
Kirk

 

[brijenjas]

Hey Sled,
I know this is an old post, but I have been following and doing the mods. to the LB phono stage and I have a question for you.
When my LB arrived I cked the PT voltage and it was 19.84 on the 15v side and 7.85 on the 6v side, I added the diodes as per your diagram and now the 15v is 17.60 and the 6v is 6.83 is that low enough ? I don't recall seeing your after mod readings, should I add more diode or will it be ok ?
Thanks,
Kirk

I had close to the same readings after installing the diodes and asked the same question. LOL.

You should add more diodes , per Sled

See posts 246 247 and 248 on page 17 of this thread:
http://www.audiokarma.org/forums/showthread.php?t=550392&page=17

 

[janikphoto]

Yes, I read the whole thread and other threads on other parts of the web, and you want below 16v and 6.3v from what I've gathered.

 

[Wharfcreek]

I don't know if it's of any consequence at this point. but while I 'was' a real supporter of this Little Bear stuff........I"m now backing off that position. I had a couple of problems with my LB SS Phono Pre.....and while the guy took care of the first, he's basically disappeared at this point and won't even respond to the latest one. The first one was pretty simple.....and obvious. He 'mis-printed' the top plate......so the 'input' was labeled as 'output' and vice versa. I wrote to him, and he was quick to acknowledge the error.....but then took about 3 months to get me the new top plate. I finally got the unit properly assembled.....and 'gifted' it to my son in Michigan.....along with a TT, an Amp, and some speakers. He was delighted and we listened some while I was up for me visit.....and even did some 'record shopping'...which was great! However, I returned to Maryland....and less than 2 weeks later the LB crapped out! Fortunately, I had a similar Rat Shack version, so I boxed that up and sent it on to his place. I just got the LB back last week when I went to Michigan again.......and have written 3 times to the LB seller on ebay......and NAHDAH! No response at all......and I'd mention that my first attempt to contact him was weeks ago after the LB crapped out. There's another LB SS Phono Pre thread going where it appears that others are failing after only a short time in service. Seems to me that the LB people need to get a better volt meter at the design lab! These voltage problems may be a bit more 'forgiving' on 'Tube' stuff.......but NOT so on SS stuff.. I won't buy LB stuff any more........ and my Tube Phono Pre may be up on BT shortly........UN-USED, NEVER PLUGGED IN, and with 'most' of these mods from this thread completed 'except' the diodes. WC

 

[Pronto]

Got my yesterday, sounds pretty good original.

 

[janikphoto]

I really need a phono pre, and this seems like the way I'll go. Shame it'll be going on the Denon 7.1 channel HT receiver in the bedroom, but I'm pleased with the phono stages on all my other stereos and the HT receiver is the only one without a phono pre built-in.