Longdog Audio P6

Hardware Review

Longdog Audio P6
Thursday, November 16, 2017
monoblock power amplifiers
Jason Kennedy

Less is more when it comes to output devices. Naim have proved that with the Statement amplifier and Gamut made the point some years ago with their D200 power amp, a product that was clearly ahead of its time. Nick Gorham appreciates that the fewer transistor pairs you have the better the sound, presumably because such devices cannot be matched accurately enough for them all to be 100% in synch. Nick Gorham runs Longdog Audio and builds audio electronics with both thermionic valves and solid state components, he knows a thing or two about how to make a decent amplifier, and a DAC for that matter, his VDT1 blew me away and is one of the few products that I can recall when asked for recommendations.

The P6 power amps are rather good too, they were created when Nick discovered that semiconductors were being made for the power transmission industry that can handle 100 Amps and produce over 900 Watts, all from a single pair of single die MOSFETs. This inspired him to build these beefy amplifiers, but the new transistors proved difficult to drive, requiring their own amplifier built in much the same fashion with a single pair of smaller output devices, with each half of the output stage being driven by its own push-pull amp. Which is why the P6 is a substantial box albeit hardly a beast given that its first 20 Watts are in Class A, but beefy enough at 20 kilos per monoblock. As Nick points out the power supply has to be up to the job of driving those output stages and this is where the mass comes from, apparently he used the biggest British mains transformers that would fit in the case.

 

 

That Class A portion of the 200 Watt total means that the P6 needs lots of heatsinking, hence the fins down each flank and the holes in the top of the case. I didn’t have enough rack space for the pair so ended up stacking them on an isolation base made for loudspeakers, the top one got pretty hot but not to a silly degree and neither complained about being left on for hours at a time. I might be complaining when the power bill comes in though! It’s worth mentioning that build quality is high throughout and that both the RCA only input and speaker cable terminals are WBTs while the IEC mains inlet is a Furutech, so top notch gear all round.

Sound quality
With the trusty Townshend Allegri preamp driving them the Longdog amps produced a nimble and extremely open sound via PMC fact.8 loudspeakers, they are easily one of the most fleet footed of power amps I have used in recent times with absolutely no sense of overhang or time smear. And the tone is to die for, high notes have a real shine to them that is devoid of any sense of grain and as open as you like. This is combined with a vibrancy that you only really get with Class A biased amplifiers be they valve or transistor varieties, in fact the latter are usually not as open as this and seem warm and rolled off by comparison. This is a full exposure amplifier that does wonders for pretty much everything you play, I stuck on edIT’s sample based ‘Ants’ (Crying Over Pros for No Reason, Planet Mu) where the speed of the amp made the most of the sharp transients in the music and brought it to life in the process. Lyrics are also very well served thanks to strong midband clarity, everything is laid out before you so that you can listen in to specific details or engage with the total musical experience. With the tabla on ‘Sharangati’ OK World (Bugge Wesselftoft, Jazzland) you can really hear hands on drumskins, it’s rich with detail and delivered with all the pace and reverberant character of the original.

With seriously good recordings like those on the Reference Records label the sense of being in the presence of the musicians is uncanny, Doug MacLeod’s ‘Too Many Misses’ (Exactly Like This) puts you in that room, it’s like being at an intimate concert except that amplified live music events doesn’t usually sound this good. Here it was the drum-kit that drew my attention in a mix dominated by voice and guitar, the instrument’s big acoustic coming up out of a warm sounding mix to take its proper place in the soundstage. Moving to the larger and from the amp’s point of view more challenging Bowers & Wilkins 802 D3 loudspeakers and dropping Ry Cooder’s Paradise and Lunch (Speakers Corner/Reprise) on the turntable brought forth bass with lovely weight and shape that underpins ultra clear vocals and the polished character of a superb recording. The scale and immediacy of the acoustic guitar is to die for thanks to remarkable resolution from the amp, there is a slight emphasis on the midrange with this speaker which makes me think it’s probably not the perfect partnership, I note that Longdog tend to use Graham Audio’s classic BBC design speakers in their demonstrations which are a very different beast indeed. But the combination proved very entertaining nonetheless and delivered some serious low end with the ‘Main Titles’ track from the Blade Runner Trilogy (25th Anniversary) where the bass oozed out and enveloped the room. It’s clean bass that sounds a lot sweeter than the variety created by Class A/B bone crunchers, which means you enjoy the tunes rather than the vibration of the furniture. I believe you can buy backpacks that will vibrate your internal organs should that be desired!

 

 

 

I also gave the P6 a spin with another preamplifier, the CAAS Elysian is a balanced design built to a very high standard that impressed me greatly when used with its partnering monoblocks. This added some muscle to the bass but retained the musical emphasis of the presentation, it also did nothing to undermine the degree of transparency by puting lots of space between instruments and delivering excellent timing.  I have to assume that Longdog Audio will be introducing their own preamplifier in future but it’s good to know that the P6 works with two such diverse alternatives as this and the Allegri.

These monoblocks have quite a lot of valve/tube character to them, they have openness that is very similar to a single ended triode (SET) combined with power reserves that few if any glass powered amps could match. Nick Gorham’s expertise with valve designs has clearly informed their character and as such made the P6 monoblock a best of both world’s product. They also offer good value, you will be hard pressed to find a pair of amplifiers of this calibre that cost less. Clearly there is something very interesting in the single pair of output devices approach, it’s the nearest thing in transistor technology to an SET and I hope to see and hear more in future. In the meantime anyone looking for do-it-all power amps with uncanny transparency should give these a listen.

Specifications: 

Type: MOSFET monoblock power amplifiers
Analogue input: RCA socket
Analogue outputs: WBT 5-way binding posts
Power output: 200W/8 Ohms, 380W/4 Ohms
Bandwidth: 5Hz to 100kHz +- 1dB, 20Hz-20kHz += 0.05dB
Sensitivity: Gain 28dB, 1.5v RMS for full power output
Distortion:
0.0004% @ 1kHz 1W,
0.0006% @ 1kHz 10W,
0.0015% @ 1kHz 200W
Signal to Noise Ratio: 97 dB Ref 1W RMS
Dimensions (HxWxD): 180 x 460 x 410mm
Weight: 20kg

Price: 
£7,500 per pair
Manufacturer Details: 

Long Dog Audio
T 07812 249747
www.longdogaudio.co.uk

 

Distributor Details: 

MCRU
T 07908 056978
www.mains-cables-r-us.co.uk