SOLD Serious Valve Line Preamplifier



Everything in moderation
Staff member
Dec 2, 2006
HiFi Trade?
  1. No
I normally keep my own builds or recycle the parts, but I'm really running out of space. Therefore, time to start moving some stuff on. First, the main ‘spare’ valve preamp. Apologies for the essay. The pics are at the bottom for the TLDR.

Five line-level inputs, 6SN7 signal valves. Valve rectified HT, choke and multi-stage capacitor filtered, mostly dual channel. Regulated low noise DC filament supply with a separate mains transformer. Moderate gain, low distortion, and around 400 ohms output impedance, so it’s able to drive virtually anything. It’s large (130H x 330W x 310D, including controls and sockets) and quite hefty.

Serious foo level. The signal valves are NOS Sylvania black plates with Herbie’s dampers, and the rectifier is an NOS National Union 6X5. Volume/balance pots are TKD and Audio Note and the selector switch is a Seiden. Signal wiring is Neotech silver/gold multi-strand, grounding is Duelund, and HT and mains is Neotech UP-OCC. The signal path, cathode and plate resistors are all Audio Note tantalum. HT capacitors are Nichicon and Audio Note electrolytics and DC-link foils. The coupling capacitors are ClarityCap CMR. All the RCA sockets are gold-plated CMC. Everything is point-to-point wired with high silver content solder. A lot of time and care went into the spec, grounding and layout, and it’s built on a ‘floating ground’ copper sub-chassis with a ground/lift switch on the rear. I’ll add in a .9m Supra Lorad 2.5mm power cable with decent connectors.

It sounds lovely, with a good 3D sound stage, excellent mids, solid bass and wide frequency extension. It’s dynamic, ‘fast’, realistic and far from ‘pipe and slippers’. Obviously this is a DIY build and controls are not labelled, though it’s obvious what’s what. The internal picture should also show that I don't take prisoners when it comes to build quality. Excellent cosmetically, with just a few small marks (and some rubs on the underside from the rack here). Most of what’s on the pictures is dust. It has only had one or two hours in the system, so nowhere near even run in yet. Pricing is difficult, but the parts alone total substantially over a grand, never mind the time involved, so I’d like a nice tidy £1000. ‘Commercial’ equivalents would cost a lot more and IMHO be no better built. In view of the size, weight and construction, I won’t risk a courier. Collection/audition is very welcome (Kettering), but I do get out and about a bit, so delivery or meet up is possible. Plus of course, the wonderful wam taxi if available/suitable. Not really interested in part/ex, as space is the real issue here. I'd rather keep it, but needs must...


Non-Smoking Man

Mar 31, 2009
Chichester W. Sussx.
Jack lambert
HiFi Trade?
  1. No
'Everything in moderation', except self-built valve pre amps!

Ive been looking for an excuse to visit Rabski so I'd be delighted if this amazing bit of kit came within my Wam Taxi's hinterland.

Christmas time is the next scheduled trip, dates yet to be finalised.
(Added - up North 22 nd, returning south 27th)

Jack NSM
Last edited:

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