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Octave Electronic M7i Tube Pre-Amplifier

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Octave Electronic M7i Tube Pre-Amplifier

Post by HiFiLab on Sat Jun 24, 2017 12:46 pm

the M7i (The simplified Marantz 7 pre-amp)  It's a tubed line-level preamp, with four sets of inputs and two outputs, all single-ended RCAs, and all solid, heavy-duty types.

The sparse fascia contains just 2 rotary knobs (for  volume and input selection) and one lil' classy-looking blue LED. Neato, and the review sample's casework came with a textured dark grey finish. Oh, the mains receptacle is a detachable IEC type, so you can tinker with different power cords.

• Chassis (metalic silver epoxy coated)
• Hairline Anodized Aluminium Face Plate
• Chrome Knobs
• ALPS Blue Velvet Volume Pot
• Lorlin Silver Plated Selector Switch w extention shaft
• Gold plated Teflon Insulated RCA Sockets
• OCTAVE PPT Polypropylene Film & Foil Capacitors for all signal coupling
• Sovtek 12AX7LPS tubes X 2
• Sovtek 12AT7LPS tubes X 1
• Fast Recovery Soft Switching Diodes
• Silver Solder

The M7's line-stage, is based around three triode sections in cascade, with the last section in a cathode follower configuration.

This helps lower output impedance allowing the preamp to drive most loads comfortably. Most crucially, it will happily drive the lowish input impedance of most modern solid-state amps — something which many preamps from the golden days of tubes can't do.

The rest of the small signal circuitry used in the original M7 is not reproduced; not many people will find a use for the extensive tone controls these days, methinks.

There is a major change implemented in the M7i, and it's the use of a regulated solid state supply. Here, the HT is regulated using a combination of discrete and integrated linear voltage regulators. Even the heater voltage is regulated so that there's no AC running around in there.

The parts quality is pretty much top notch — you ain't gonna see an Alps Black Beauty sealed volume pot on any mainstream commercial product anywhere near this price, so this was a surprise.

Supply capacitors are Nippon Chemicon while signal caps are either Philips film caps or Wima Red Bricks. The high-voltage rectifiers, meanwhile, are the expensive fast-recovery types rather than the usual 1N series silicon foot-soldiers — wot luxury, eh?

The one thing that I have some doubts about is the ultra-thin teflon coated wire-wrap wire used for signal wiring — many DIY types will have problems stripping this unless they have some pretty sharp pre-settable cutters. Still, it does sound much better than the ordinary thick stuff, so it's worth the wrestle. I tried using my teeth and it didn't work ....  

Price : RM 1250
Contact Simon Ting 012-3612507

Dealer\Reseller\Trader\Service Provider
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Number of posts : 2179
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Location : klang
Registration date : 2011-03-12

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