FS: Neurochrome 686 or PX for Lyngdorf

[Mr.Ian]

Being toying with simplifying my set up for a while, loss of job and the need to get a newer car has brought it to a head.

First to go is my beloved Neurochrome 686, best power amp I have/will ever own £2200 collected from North Nottinghamshire close to M1 J28
Price is firm

The amp was professionally built by AD Audio and has the slow start and speaker protection circuits - note many of the units offer on ebay dont appear to have these.

see AD Audios orginal sale post below:

https://theartofsound.net/forum/showthread.php?72588-Neurochrome-686-Brand-New-Build

Note: the unit has been in my rack since I bought it, the only mod being the addition of an earth socket to the rear. I use it for grounding my sub woofers that run in balanced mode. I takes the form of a discrete, green, 4mm socket that is isolatated from the rear case and then wired to the amplifiers central earthing point.

https://i.imgur.com/FRj3hHF.png

[hifinutt]

beautiful ....

was just admiring JH new 686 monoblocks on ebay this week

great price for a lovely unit

wonder what the weight is?

[Mr.Ian]

I saw some monoblocks listed at £3k but dont think they have the Neurochrome intelligent soft start and Neurochrome Guardian speaker protection fitted.
Bet if these had been included the price would have been closer to £4K; the extra parts are close to £500 plus shipping and vat

The amp is very heavy, its a one person lift BUT I wouldnt want to carry it too far. Never tried to weigh it

[Ali Tait]

The monos are the same as the pair I have just bought and they do indeed have speaker protection fitted. Soft start is provided by a thermistor.

[Mr.Ian]

I can't see the Neurochrome guardian board in the ebay pictures

[Mr.Ian]

Looking on ebay you can buy speaker protection modules for under £5 delivered. Neurochrome are, reassuringly more expensive.

[Ali Tait]

It’s not a guardian board, it’s from a different manufacturer but does the same job.

[Mr.Ian]

Precisely

[Mr.Ian]

https://www.diyaudio.com/community/threads/guardian-86-and-guardian-686-high-end-speaker-protection-circuits.328394/

[CageyH]

I have a Mod 686 of a very similar spec, if not identical.
It is all the SS amp you will ever need.

[Mr.Ian]

No one interested in a fully specced 686?

[Mr.Ian]

Half way meet up or even delivery may be possible dependent on location

[Mr.Ian]

£2k collected between Xmas and new year. Final bump before the bay at £2.5k to cover fees etc

[Mr.Ian]

This is the ultimate Neurochrome 686 power amplifier.

Construction is fully dual mono, fully balanced with XLR inputs and 4mm banana speaker terminals
The rear panel also includes a 4mm earthing terminal for subwoofers.
Despite its high power output this differential/balanced amplifier turns on and off without a thump or buzz, just a small click as the relay clicks over.

Output Power 240 W 8 Ω, < 0.01 % THD+N
Output Power 360 W 4 Ω, < 0.1 % THD+N

Professionally assembled by AD Audio in the UK using Neurochrome boards throughout.
Many builds omit the following Neurochrome boards to save money.

This amplifier includes

2 x Power 686 power supply boards – one for each channel
• Optimized PCB layout featuring the elaborate use of copper planes and pours to minimize parasitics.
• Simple capacitor snubber to minimize diode switching noise. Option for CRC snubber for advanced builders.
• Four discrete diodes with individual heat sinks.
• Four 22000 µF, 50 V reservoir capacitors. Snap-in capacitors up to 40 mm in specified diameter supported.
(The transformer is rated at 800 watts - 2 x 400 watts @ 25v ac. One winding for each channel)

1 x Neurochrome Intelligent Soft Start
When a power amplifier is first turned on, the mains transformer will draw significant current for the first few mains cycles as the magnetic field builds within the transformer core. The inrush current can reach several hundred ampere, which severely stresses the transformer. Furthermore, to accommodate the high inrush current, the mains fuse used to protect the transformer and connected circuitry must be grossly oversized, which limits the effectiveness of the fuse in the event of a catastrophic fault in the circuit. The Intelligent Soft Start (ISS) solves this issue by limiting the inrush current to a safe value using a NTC resistor. Once the magnetic field has been allowed to build within the transformer, the soft start circuit shorts out the NTC resistor with a relay.

2 x Neurochrome Guardian-86 speaker protection – one for each channel
The Guardian-86 is a high-end protection circuit designed to protect speakers against two common ways that power amplifiers can misbehave:
• Sharp voltage transients on power-up and power-down, resulting in annoying clicks and pops in the speakers.
• Excessive DC voltage on the output of the amplifier, for example resulting from amplifier failure or from unruly signal sources.

[Mr.Ian]

Withdrawn from sale

[Mr.Ian]

just priced up what it would cost to build to this spec and I get £2900 plus time and solder !

[Patrick Dixon]

Yeah but you've withdrawn it so it doesn't really matter!

[Mr.Ian]

No real interest and I was away - I have an ebay listing in draft waiting on a selling fee offer. If if anyone has serious interest they can contact me - my overall goal remains system simplication

[Mr.Ian]

This is available at £2000. An absolute bargain for an amp of this quality.

[Mr.Ian]

Happy to deliver or meet up - circa 2 hour drive from M1 junction 28,

[Mr.Ian]

need the cash, so it looks like I am going to loose and arm and leg on this, a bargain awaits - serious and sensible enquiries only please

[Mr.Ian]

Don't be put off by the xlr inputs. I can include suitable adapters for those who need single ended rca inputs