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Little Bear Tube Phono Pre??

Oredered the EMI filter as the seller claims will eliminate back noise. Will see if it works when I get it.
 
cheehpogi said:
Oredered the EMI filter as the seller claims will eliminate back noise. Will see if it works when I get it.
Click to expand...

I bought the thing too, but if it doesnt do anything I will be making a paypal claim.

SMPS generate back noise. An all tube phono stage wouldnt be doing that.

I think there is a chance the inductors might stop some high frequency noise getting into the circuit. But I didnt see any of that on the CRO. So, I doubt this will do anything, but wait and see.
 
Well had it for a week now and really impressed. Thinking of trying new tubes. Will any make of 12AX7 fit.Do you also need to replace the 6Z4 tube as well. Any advice greatly received
 
I've got some money built up again that can be spent at Amazon, and last time I checked there was a little bear and another chinese riaa preamp... the YAQIN MS23B. I'm not finding the little bear now, though. What are your thoughts on the Yaqin, and what are my tube rolling options with it?
 
Hi guys,

new to AK and new to tube amps. I got 4 days ago my LB with version 2.5 and finally I could run my new turntable.

At first I put it together and ran it like it was. The hum was OK and not to loud. Found today a tube shield for the first stage and hum is nearly gone.
Sound was great, much better than that what I had with an integrated phono stage some years ago. It is fun to get back into vinyl with the little bear...

My version came with a set of 12AX7. I also ordered together with the amp another set from the same vendor which is 6N2 tubes so I have two different sets of tube. Down the road I will figure if there is a sound difference between them. Both sets of tubes are chineese. Running at the moment the 12AX7.

Now reading through all the threads above I checked it a little bit further out. My voltages are 208V, 6.4V and 16.4V. Line voltage at the location I plug it in is 122V.
I'm not so much concerned about the 208 and 6.4 but the 16.6V are a little bit high. Don't have the right diodes in my collection, only 1N4004 which can only run 1A. I will need to get some 5A from HSC.
Now what I figured out, the transformer is getting really hot. I wonder how much is going over this little thing that it gets so warm.
Also the 16.6V are dropping a little bit with run time, when the trans is hot it goes down to 15.8V. With this and a 1.2V drop over diodes later would it be a problem to run in the 14.XV down the road?

I'm not sure if I want to run high or low gain. So far I can't hear a difference.

Axel
 
darg said:
Hi guys,

new to AK and new to tube amps. I got 4 days ago my LB with version 2.5 and finally I could run my new turntable.

At first I put it together and ran it like it was. The hum was OK and not to loud. Found today a tube shield for the first stage and hum is nearly gone.
Sound was great, much better than that what I had with an integrated phono stage some years ago. It is fun to get back into vinyl with the little bear...

My version came with a set of 12AX7. I also ordered together with the amp another set from the same vendor which is 6N2 tubes so I have two different sets of tube. Down the road I will figure if there is a sound difference between them. Both sets of tubes are chineese. Running at the moment the 12AX7.

Now reading through all the threads above I checked it a little bit further out. My voltages are 208V, 6.4V and 16.4V. Line voltage at the location I plug it in is 122V.
I'm not so much concerned about the 208 and 6.4 but the 16.6V are a little bit high. Don't have the right diodes in my collection, only 1N4004 which can only run 1A. I will need to get some 5A from HSC.
Now what I figured out, the transformer is getting really hot. I wonder how much is going over this little thing that it gets so warm.
Also the 16.6V are dropping a little bit with run time, when the trans is hot it goes down to 15.8V. With this and a 1.2V drop over diodes later would it be a problem to run in the 14.XV down the road?

I'm not sure if I want to run high or low gain. So far I can't hear a difference.

Axel
Click to expand...

Can u post a pic of the "tube shield" please?
 
I'm planning to change caps for PIO's. When buying them what voltage should i get ? The original WIMA's in LB are 400v but 250v pio's are easier to get for me. Will this voltage be enough or its safer to get 500v PIO's or higher ?
 
What I would like to know is what is the smallest 12V transformer I can use for bucking.
Seeing how it's a 110V transformer I'd like to drop line voltage form 124V to 110V.
Running with a variac at 110V all secondary voltages correct and transformer cooler.
Have mine in a case and would like to add an internal bucking transformer.
Case too small for the 3A and 1.5A I have.
Will a 12V 450ma be big enough? or will I burn down the house?
 
fetor56 said:
Can u post a pic of the "tube shield" please?
Click to expand...

Hope this shows it. I found that thing in a corner of HSC here in Sunnyvale.

album.php


It was a spring loaded one but the spring was too long and would have hold the shield way too high. I took the spring out, cut it shorter to one winding and it fits. It keeps a little gap to the tube top. Also it fits snuggly with the cover of the housing.

Axel
 

Attachments

  • Tube Shield (1).jpg
    Tube Shield (1).jpg
    66 KB · Views: 156
The hole in the cover fit pretty nice with my shield, so no cutting here. Not sure how the dimensions vary for the shields and also covers.

I'm planning on running the 12AX7 tubes for a month and switch than to the second set and compare. Want to get at first the voltages correct.

Axel
 
Darg, you wouldn't happen to be the person who accidentally got my Little Bear? The seller shipped two to CA, one was suppose to go to me in MN. Just curious.
 
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