View Full Version : Anyone tried the little bear valve pre amp?
Hi All,
Apologies if in the wrong section, please move if so.
Just finishing off building my gym in the garden and i am putting my spare cambridge azure amp and monitor audio br2 speakers. Source will be mainly my mac book air or iphone through headphone socket. Not the best by a long shot but ok for now. Question is as i love gadgets! Is it worth taking the plunge on an ebay special its a valve pre amp from little bear company.
Just wondered if it is worth trying!? Or just a waste of nearly £50
Thoughts please
http://www.ebay.co.uk/itm/281492870947?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Firebottle
30-04-2015, 07:12
Do you need more gain in your system? If so should be worth a punt.
However the drawback with this unit is that the 6N3 has a different pin out to the standard ECC8x range, so no easy tube rolling.
:) Alan
Hi Alan,
Thanks for the reply & could you explain what you have said!?, tbh those 2 questions went straight over my head sorry. I am probably being naive with them - i am basing it on the fact that the BM mk2 i have has greatly improved the audio from my mac mini & was wanting a 'cheaper' set up in my new garden gym & have always wondered about valve amps/pre amps but find it difficult understanding them. Was thinking they did a similar thing to a DAC and would hopefully improve the sound from the macbook or any general source that passes through it. I am lured in with this phrase 'warmer sound' :lol: and just wanted to dip my toe in & try it
Firebottle
30-04-2015, 08:43
No problem Tim. A number of folks misunderstand the difference between the gain (multiplication) in a system and the output power, whether it's 2, 20 or 200W.
Gain in electrical terms is the amount by which a signal is increased. Another word is amplification which is where the term 'Amplifier' comes from.
Simply put the relative gain determines how far round you have to turn the volume control. If you found that you had to turn the control up to full to get the required level then adding more gain (amplification) to the system would mean the volume control would only need to be turned part way to give the same level.
Any stated maximum power output from a power amp or integrated ONLY states how much energy (or push in a physical sense) is available. An analogy is maximum water pressure from your tap, you can't get any more flow. The sound level produced is dependant on the efficiency of the speakers in converting electrical energy to acoustic energy.
As far as valves go a lot of equipment uses the ECC81, 82 and 83 type of valve or similar. These have the same connections on the pins of the valve so can be interchanged in the same valve socket, a practice known as 'tube rolling'. Because these valves have been used a lot there are many manufacturers to choose from for tube rolling.
The 6N3 valve in the Little Bear has differently arranged connections to the valve pins, so you are stuck with only using that type of valve. I think it is only made in China (unless anyone knows different) so the sound quality of the Little Bear is restricted to the quality of the 6N3 chinese valves.
Happy to answer any more questions,
:cool: Alan
right ok, thanks for the info, makes sense! ok, so i need really to look for a little valve amp that i could 'upgrade' the valves if i so wish in the future as it is these that in the end help to improve the sound (hope im right in saying that?) & that the standard valve(s) in this - basically thats it like it or lump it.
Will look to see if there are any with the specs you mention so at least i have a base & i like to tweak :eyebrows:
if gain is not a problem maybe you are looking for a valve buffer ..... there are a number around at varying price levels. they can add a little bit of valvy sound to the mix(actually they add a little distortion) lol. handy things and i have one on the end of my pc system ...i find it just takes the edge off the highs making for a more rounded sound
Hi Struth,
thanks for the info - could you elaborate or point me in the right direction to a few on ebay please?
www.ebay.co.uk/sch/i.html?_odkw=buffer+a.p&_from=R40&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.Xbuffer+am plfier.TRS0&_nkw=buffer+amplfier&_sacat=0
lots of differing ones..ive had a yaqin b4 but got a cracker now in a musi al fidelity
some copies here
www.ebay.co.uk/sch/i.html?_odkw=musical+fidelitybuffer+amplfier&_from=R40|R40|R40&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.Xmusical+f idelity+buffer+amplfier.TRS0&_nkw=musical+fidelity+buffer+amplfier&_sacat=0
my current one
www.ebay.co.uk/itm/121615665037?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
quick update,
just decided to finally buy a little bear p5 pre amp type valve with 2no. cheap chinese 6J1 valves in it.
I have also ordered & taken delivery of 2no. replacement Mullard 5654 tubes to try once ive listened to the stock tubes.
I will have it set up from my macbook air laptop via airplay through to the apple airport express then a 3.5mm jack from that to twin phono/rca to my cambridge audio azure 540v2 amp & Monitor Audio BR2 speakers.
I also ordered some reasonable Proel Challenge interconnects - just got to wait for it all to turn up & give it a whirl!
items:
Little Bear Valve pre amp: http://www.ebay.co.uk/itm/271712368276?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Mullards: http://www.ebay.co.uk/itm/261382013444?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
lead 3.5 to phono: http://www.ebay.co.uk/itm/330790470491?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
lead phono/phono: http://www.ebay.co.uk/itm/331237159517?_trksid=p2060353.m2749.l2649&var=540418155749&ssPageName=STRK%3AMEBIDX%3AIT
very budget i know but lets see what its like! :lol: hopefully be pleasantly suprised :)
awkwardbydesign
30-07-2015, 11:18
Bet it won't look as cute as this, though! http://www.ebay.co.uk/itm/Vintage-5725-Vacuum-Tube-Buffer-Processor-Pre-amplifier-FR-CD-DVD-MP3-DAC-MOBILE-/221218828679?pt=LH_DefaultDomain_0&hash=item3381ab7187
http://i.ebayimg.com/00/s/NzUwWDY3OA==/z/2fAAAOxylk1ReQ-L/$(KGrHqNHJE4FDLUgUf3HBReQ-K)dvw~~60_14.JPG
Hi Tim,
Please do keep us informed on your progress and how the Little Bear P5 sounds to you.
I just picked up one for a fiver, but it did not come with a power supply, and one of the valves was cracked and had lost it's vaccuum! How the seller could describe it as 'working' I don't know. No problem for me though, as I'll build a new power supply, and replace the valves either with Mullard or GE ones. I'll probably put the whole thing in a proper box with a nice Elna 6 way switch so that I can run multiple sources.
awkwardbydesign - yes they do look pretty good dont they!
Desmo - yes will get pics & progress up as & when they turn up :thumbsup: - was yours a 2nd hand unit or just new & badly packaged? Sounds good your idea with what you will do with it as well, get that posted up would love to see how that is done :)
Tim, it was a second hand unit. I'll let you know how I get on, it will be a nice little project.
little bear P5 has finally arrived at work today! fitted the 6J1 tubes supplied with it as i want to make sure it works ok 1st. Looking forward to going home on my lunch break & plugging in for 15 mins & then have a listen :)
Dauntless
06-08-2015, 13:42
As I mentioned on a previous thread I have a Little Bear pre but mine is the one with the 6Z4 rectifier tube that has it's own transformer which can be yours for £46. I have had it looked at by David Lane of Valve Amp Repair and he has made it safer for UK use and sorted the transformer to run on UK mains. This cost me a further £70 so I have a class A Valve pre for very little money.
I wanted an active valve pre to humanize my Class D power amp and I am happy to say this cheap pre does the job very nicely. Just been playing Clive Gregson and Christine Collister Mischief CD. Very nice presentation, great CD.
little bear P5 has finally arrived at work today! fitted the 6J1 tubes supplied with it as i want to make sure it works ok 1st. Looking forward to going home on my lunch break & plugging in for 15 mins & then have a listen :)
Hi Tim how does your version sound then?
I've just plumbed in my LB P5 and it sounds OK, perhaps a little restrained, but it's only been playing for 5 minutes, so will probably take a while for everything to settle down. I ended up making loads of changes to the secondhand P5 that I got for a fiver.
I've replaced all the valves, capacitors, diodes, socketry, one resistor and the volume pot. I've also built a new PSU using a 2nd hand torroid, a push button on/off switch, and put it in a bigger box with 6 inputs and a selector switch - so it really looks and acts like a full blown pre amp now.
Well I've put a few more hours on the P5 now, and the sound is definitely opening out, better sound stage, and both bass and treble seem to be nice and clean. I've had a few pre amps over the years, and this one is actually surprisingly good given its budget origins.
Hi, yep bang for buck really impressed! Put the mullards in and its ran for a out 20 hrs now an i must say its growing on me. Vocals seem warmer an smoother, cant say its a huge improvement but for vocal songs an good audio its a nice listen. Dont forget its only fed from a macbook air an feeding a cambridge audio amp but i must say its clean, clear an spacious sound, im happy!
I bought a P5 about a year ago for £25.
It came with a very small transformer marked 18v which got extremely hot. I replaced this for a larger transformer of the same voltage. Initially the valves glowed brighter but then the capacitors started to explode. I rebuilt it with higher voltage rubicon caps, but there is just a terribly loud hum as soon as it is plugged in regardless of the position of the volume knob. The new caps haven't exploded but something is very wrong.
Possibly a damaged diode?
Firebottle
18-09-2015, 15:33
Possibly a damaged diode?
Very likely as the HT is derived from a voltage ladder. Any one of the diodes being faulty would cause a hum to be heard.
:)
Well the circuit board has 18v AC printed on it, but I have recently seen them for sale with 12v AC supplies. The heaters didn't glow on the tubes until I introduced the 50w 18v AC supply.
Do tube circuits need to have their current limited? I am new to tubes, not sure if the usual current draw rules apply (only taking what is required).
Or is it just a case of bad quality chinese components? It seems the tubes drew too much power for the cheap diodes and capacitors and I am not keen on throwing any more parts at it if the transformer I'm using is too big for the job. At least diodes are easy to test.
I
Well the circuit board has 18v AC printed on it, but I have recently seen them for sale with 12v AC supplies. The heaters didn't glow on the tubes until I introduced the 50w 18v AC supply.
Do tube circuits need to have their current limited? I am new to tubes, not sure if the usual current draw rules apply (only taking what is required).
Or is it just a case of bad quality chinese components? It seems the tubes drew too much power for the cheap diodes and capacitors and I am not keen on throwing any more parts at it if the transformer I'm using is too big for the job. At least diodes are easy to test.
I replaced all the diodes with better UF types, I think the originals were 1N4007, so I would have used UF4007's. I also replaced all the caps with better ones, and replaced R1 with something better than the coffin type resistor that the unit came with. I'm using quite a decent sized torroid transformer, and probably made a few other changes, but it sounds pretty good now! Far better than you'd expect. As I mentioned in a post above, my P5 only cost me £5.00 and came with a broken valve and no PSU, so it was always going to be a bit of a project.... Quite good fun though!
So yours is stable being fed 18v from a big toroid? Good to know. Looks like I will return to this in due course. LDR Chris also wrote about these UF diodes, maybe I should be putting them in everything I build. Have to change the diodes in a Rega Planet so looks like UF4007's are going in, and they're under 5p each :)
http://www.ebay.co.uk/itm/UF4007-Ultrafast-Diode-Switching-1KV-1A-2-Pin-DO-41-Pack-of-100pcs-/301506569542?hash=item4633312546
I have a couple of NOS Russian EF95 Vokshod tubes that I would like to try in it. Bought a few sets of them thinking they were suitable for Lampizing CD players but they aren't. Luckily Little Bear use that type.
So yours is stable being fed 18v from a big toroid? Good to know. Looks like I will return to this in due course. LDR Chris also wrote about these UF diodes, maybe I should be putting them in everything I build. Have to change the diodes in a Rega Planet so looks like UF4007's are going in, and they're under 5p each :)
http://www.ebay.co.uk/itm/UF4007-Ultrafast-Diode-Switching-1KV-1A-2-Pin-DO-41-Pack-of-100pcs-/301506569542?hash=item4633312546
Yes perfectly stable now. Do check the Diode type though, I think they were 4007's, but don't have my notes to hand. If they were 1N4003 or whatever, then substitute UF4003's ... I've built mine into a case, so can't easily see what all the parts were. Pretty sure I have GE5654W valves in at the minute, but I've got a couple of pairs of Mullard's to try out sometime when I have the time.
Awesome, thanks for sharing that :) I had shelved it for the time being....
My P5 is going to be part of little micro-fidelity project with a 9023 DAC and TA2021B amp:
http://s29.postimg.org/9pcr7p1rr/P1040768.jpg
Those amps can run in BTL for dual mono. Must get another one.
The diodes are indeed 4007's. Checked them all with the meter and they measure the same. I guess one end would need to be lifted in order to test them properly.
Will just replace the lot with UFs as per your suggestion, and hope that fixes the noise.
Do all 5 diodes, the four forming the bridge rectifier (D2 - D5) and the other one (D1) on the board. Also pay attention to the earthing of the board, as the original 2 wire transformer did not include an earth.
Dauntless
19-09-2015, 11:36
I have a Little Bear P5 which is as it was delivered. Mine does not have a great hum problem. My friend has one as well and his is ok. The transformer does run hot though.
I also bought the Little Bear 6N3+6Z4 class A pre. I have had it fettled as the transformer is 220v, it is not earthed and the mains lead is dodgy.
I had this done by a guitar amp maker in Kent for the very reasonable price of £70. There is still some hum with this unit but with my system it is very slight indeed. In my system the 6N3+6Z4 is the better pre. I've finished up with a firsr class valve pre for around £120 and I'm very pleased!
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