Buffer Stage Solution To Impedance Matching (Albarry).

[Audioman]

I was coming to the conclusion that something was still lacking soundwise using my Albarry Monoblocks and decided to investigate an affordable solution. One would be a used Puresound L10 but these come along like buses and I missed a couple last autumn. Googling Buffer stage came up with a number of designs usually from US and expensive. I also found an interesting product from Lehmann but retail of £570 to £670 looks a bit steep for the electronics involved. Then I saw one on offer from Henley Designs Ebay shop at £279. Too good to miss as I am not going to lay down £2.5K on a new Albarry or Puresound pre to prove how crucial matching is to the low impedance of the Albarry M608.

Manufactures blurb -

The name Lehmann audio has long become synonymous for producing cost effective state of the art audio electronics. The Black Cube Buffer is a high end cable driver that satisfies the highest demands and is the solution for practically all problems with long cables or different levels.

Many music lovers have an affinity to puristic concepts like the so called passive preamps. Although there are certain qualities, these setups are facing problems with long cables. The sound is often too soft and weak. Highs lack transparency and bass impact is also dissatisfying. This is mainly caused by a high source impedance of the passive attenuators.

The Black Cube Buffer is the ideal partner. Due to the low impedance output driver circuit realised as high current Class A design without global negative feedback the music flows unaltered, artefact free and with all its inherent energy to the next following input.

Another application for the Black Cube Buffer is the field of biamping where low efficiency woofers are combinded with much higher efficiency midrange drivers and tweeters like for example horn system. In many cases the gain reserve for the woofer is insufficient. Here the Black Cube Buffer can be effectively used for level optimisation.

Weak output stages of any line sources can greatly benefit from the Black Cube Buffer. Especially variable outputs of CD-palyers are very often dimensioned inferior. This is often the reason why a seemingly puristic combination of CD-player, power amp and speakers sounds dissatisfactory in so many cases.

With the Black Cube Buffer such setups can turn into highlights!


Technical Data:
Input impedance: 47 KOhms
Maximum gain: 0dB, 10dB, 20dB switchable underneath the unit (actually 28db as well)
Maximum input level: 9V at gain 0dB, 900mV at gain 20dB
Maximum output level: 9V RMS
Frequency response: 10Hz (-0.3dB) to 60 kHz (-1dB)
Signal to noise: >95dB at 0dB gain
THD: <0.001% at 6mW/300 Ohms
Channel separation: >70dB/10kHz
Output impedance: 60 Ohms
Power dissipation: <5W, internal, regulated power supply
Dimensions: 280 x 110 x 44mm3 (case only)
Connectors (audio): gold plated RCA connectors with Teflon isolation
Weight: app. 1.4 kg

Suggested Selling Price: £575.00

Knowing the reputation their phono stages have I took a punt and got another 10% off with a paypal voucher.



Linked in between a passive and the monos this provides a 60 ohm output which gives close enough to 1:100 ideal ratio between pre and amp. It also has facility to increase gain (4 settings). I left gain at zero which proved fine in this case. The difference this makes is surprising. Everything tightens up with more drive, better bass, sharper highs and more detail. Sound is more up front and a little less spacious but everything is more in focus.

Paul.

[Reffc]

Excellent product Paul (like all of the Lehmann stuff imho) but a little expensive for what it is. At the price you paid, it's reasonable value. I think they might be relatively simple circuits using switchable op-amp circuits for gain. The one I built was 100 ohm output from memory and unity gain (cost to build was £27). You could have had it at cost if I'd known you were after one! You're right though, they do allow a better response, particularly in the bass. More balanced, so a good solution allowing passives or any valve active to be used with the M608. Once you get hooked on the Albarry's strengths, there's no going back

[Audioman]

Excellent product Paul (like all of the Lehmann stuff imho) but a little expensive for what it is. At the price you paid, it's reasonable value. I think they might be relatively simple circuits using switchable op-amp circuits for gain. The one I built was 100 ohm output from memory and unity gain (cost to build was £27). You could have had it at cost if I'd known you were after one! You're right though, they do allow a better response, particularly in the bass. More balanced, so a good solution allowing passives or any valve active to be used with the M608. Once you get hooked on the Albarry's strengths, there's no going back

Hi Paul.

Judging by it's weight there may be a little more to it incl a substantial transformer. Nice case and switchable options probably cost price around £100. Treble that for sale to importer then add up to 40% each profit for distribution and retail. I am now seeing some dealers asking one hundred pounds over the suggested selling price for Lehmann products making this £675.

As an aside have you tried their Decade phono stage and if so is it a worthwhile step above the Black Cube SE II?

Paul.

[Reffc]

Yes, the weight is a small power supply, but it's basically switchable op-amps on a PCB with some resistors/diodes and caps. The power supply is probably quite good on that model and that plus the casework is where the expense is really. As you say, nit out of the way once margins applied but at £675? Come on...that's taking the micky.

I haven't heard the Decade PS but really do rate the Cube SE...cracking bit of kit at the price. I imaging the Decade is very good but still await an audition of one.

[Clive]

I see Burson don't do their buffer any more. iFi do their iTube though which is very good.

[adam_ecofansound]

hi,

don't forget icon audio:

http://www.iconaudio.com/portfolio-i...i-musical-box/

first watt:

http://www.firstwatt.com/b1.html

and, humbly i might add - ecofan:

http://www.ecofansound.com/bufferzone/

interesting result with the lehmann - haven't
had the chance to listen - not widely stocked
here in new zealand,

cheers,

adam