‘Little Bear’ Moving Coil Step Up Preamplifier T8-1

[mikmas]

Can you remember when all N.A.D buttons looked like Tootie Fruities?

Yep, used to rib my mate about it back then - he was a NAD fanboy
As you say - it's what's in the box that counts (although I draw the line at shocking pink....)

[Barry]

I have never owned any Quad gear, but those that do seem to be satisfied.
Do they persist with the Fischer-Price look or is yours a vintage unit?

Well I have never heard the term 'Fischer-Price' used to describe the cosmetics of the Quad Series 4 electronics before. Certainly the looks and styling are individual and distinctive - sufficiently so for Quad to have been given a Design Centre award for all their Series 3 and Series 4 electronics. As to the colour: Quad 'Bronze' (although I think 'snot-green' is more descriptive), well they are a bit of a Marmite thing but then I also love Marmite! Most of my Quad gear does sport the older livery, but I also like the slate grey colour of the later Series 4 electronics and of the Series 5 and 6 electronics.

I fact I love Quad equipment full stop: for the design, styling, build quality and, dare I say it, for the sound. Quad equipment is superbly well made and reliable. Not for nothing is Quad gear used by the BBC and by many recording studios.

To say I’m a bit of a Quad lover is a bit of an understatement, I have about 18 items of Quad gear. You can, if you are interested, read of my love affair with Quad here: http://theartofsound.net/forum/showt...ight=Life+Quad

[worrasf]

‘Little Bear’ Moving Coil Step Up Preamplifier T8-1





Prompted by Ali Tait’s mention of this amp, I thought I would take a punt. It arrived today, so I plumbed it into my system. The cartridge is a ‘cooking’ Denon 103 and the headamp feeds the DISC input of a Quad 44 (sensitivity set to 3mV), connected by a pair of 1m RG-223/U-01 cables.



At only £20 I wasn’t expecting too much, but I was very pleasantly surprised by what I heard. Until now I have been using either a Linn LINNK phonostage (actually made for Linn by Naim and based on the circuit of the Naim 323 boards) or either a Mark Levinson ML-25 phonostage or a ML-10A preamp. All of the latter are considerably more expensive than the Little Bear T8-1!

OK, the Little Bear doesn’t trounce any of the above devices, nor would I expect it to, but it does sound very good indeed; and for the price astonishing. I played Dire Strait's eponymous LP: all the sublety I associate with this album as well as the tight, driving, rhythm were there. Next up was Linda Ronstadt's 'Hand Sown, Home Grown', a good test for treble control, as Ronstadt's voice can sound hard and edgy if there are problems in the replay chain. The Little Bear sailed through this hurdle. The sound stage is not as deep as that with either the Linn or the Levinson designs, and the treble can at times, ‘shout’. But for £20 it’s bloody fantastic!


Being an inquisitive person I just had to take a peek inside, to see what £20 bought you. Not surprisingly the circuit is simple – dead simple: just a single transistor (marked as K184 (a BC184 perhaps?)) per channel, drawing a collector current of ~2mA.





A single Elna 470uF input coupling capacitor is followed by a shunt 680Ω resistor. The emitter resistor is 1kΩ, bypassed with an Elna 470uF capacitor. The output is taken directly from the collector.

Raw 12V AC from a 'wall wart' is rectified by a bridge rectifier and then smoothed by a 200uF electrolytic, itself bypassed with a 100nF capacitor. This in turn feeds a linear voltage regulator using a 12V Zener diode reference. Hum and noise is commendably low, but of course, not as good as with either the Linn or the Levinson amps. Switch spikes are not as well suppressed as they are with either Levinson product (which appear to be totally immune to switch spikes) - in fact they are quite bad (but then so too is the Linn LINNK in this respect).

Such a simple circuit has no right to sound as good as this. With a little fettling, such as perhaps upgrading the capacitors in the signal path, and replacing the Chinese sourced 200uF caps in the power supply, the performance could well be further improved. However, as it stands, this little device represents excellent VFM and is to be commended.


The published specification for the Little Bear T8-1 head-amp is as follows:

Step up ratio: 1:10 (i.e. 20dB)

MC input support: Moving coil cartridges 0.3 - 0.8mV, impedance 20 - 100Ω
(by this I take it to mean the amp will be suitable for those MC cartridges requiring a loading of 20 - 100Ω)

Output: 3 - 8mV, impedance 47KΩ
(i.e. the RIAA equalised input of the preamp will have an input impedance of 47kΩ)

Frequency range: 20 - 20,000Hz +/- 0.5dB

Distortion: < 0.1%, 1kHz

Power: 12 - 18VAC, 100mA

Great write-up. I saw these on eBay and would have passed if not for your findings so I've just ordered one to try while I figure out a way to get a bit more gain from my Croft headamp. The NWA DL103 has a lower output than stock and I desire a bit more gain. I will then use it with my NetAudio Quad 33/303. I'm currently using an AKG P8ES supernova in an SME 3009 II on a Thorens TD150 with it but will be nice at this price to have the flexibility of an MC as well - be keen to hear how my Zyx R100 H sounds through the Quad - I think it might be a bit too "fullsome" in the midrange though.

[Barry]

Thanks for your kind comments Stephen.

At £20 you have little to loose, but I think your NWA 103 deserves a much better head amp than the Little Bear design.

Agreed you can use it as 'stop gap' whilst you discuss with Glenn how the gain of your Croft amp might be increased. Remind me of the output of the NWA 103. The stock Denon 103 has an output of ~0.35mV (at 5cm/s).

Regards
Barry

[worrasf]

Hi Barry - Dom didn't mention a figure when I spoke yesterday just that
it was lower - I would estimate about 0.2 given the difference between
the stock Denon and the Zyx which is 0.8mV.
Glenn reckons there is a bit of gain to be had in the headamp but it needs
some components (unspecified) that were discontinued years ago
but he is on the case. Alternatively, he says there is lots of gain to be
had from the 25R with a MOSFET so I have definite options.

[Barry]

Hi Barry - Dom didn't mention a figure when I spoke yesterday just that
it was lower - I would estimate about 0.2 given the difference between
the stock Denon and the Zyx which is 0.8mV.
Glenn reckons there is a bit of gain to be had in the headamp but it needs
some components (unspecified) that were discontinued years ago
but he is on the case. Alternatively, he says there is lots of gain to be
had from the 25R with a MOSFET so I have definite options.

So you're looking for an extra 5dB of gain, or nearly double the sensitivity. Good luck with project.

At least the Little Bear will get you 'up and running', but ultimately it is not worthy of a £1,350 cartridge!

[Ali Tait]

If you can find one, the Denon HA 1000 is a great bit of kit.

[worrasf]

So you're looking for an extra 5dB of gain, or nearly double the sensitivity. Good luck with project.

At lest the Little Bear will get you 'up and running', but ultimately it is not worthy of a £1,350 cartridge!

Yep. TBH I'm listening to the NWA DL 103 now (Nude Ants - Jan Garbarek) - sounds stunning and in actual fact the vol pots
are at 5 o'clock with perfectly acceptable volume so maybe I just needed a few hours to "adapt" to the new settings.
It would be nice if Glenn can source the bits for the headamp - since he fettled it and added an external PSU it really is darn good
Anyway, the LB will be useful for the Quads - at £20 I can't go wrong

[worrasf]

If you can find one, the Denon HA 1000 is a great bit of kit.

Thanks for this.
I've been disappointed by the SQ of a few SUT's I had in the past including a Dynavector SUP 2000 which was not cheap. The Croft headamp by contrast is superb but I will look out for an HA 1000

[lurcher]

marked as K184 (a BC184 perhaps?)

More likely a 2SK184 jfet.