Audio Research SP-3A-1 Vintage Tube Preamplifier - Collector Grade Restoration - Reviewed By The Audiophiliac

**Please click here to check out our newly launched SkyFi Audio website with additional items for sale**

This is a collector grade restoration of a classic and well regarded preamp from Audio Research. The exact model designation is SP-3A-1.

Many consider the SP3 as the finest preamp ARC ever produced. Its classic looks and reliable operation have made this piece a favorite among collectors.

PLUS Steve Guttenberg "The Audiophiliac" recently reviewed this EXACT item on his YouTube channel!

This comes to you with it's rare original wood case (!) which takes the looks to another level. Absolutely gorgeous.

An excellent match for any vintage system using speakers that might require a bit of boost from the built-in tone controls.

You're not going to find a finer electrical restoration. Even the tubes are upgraded to "new old stock" GE JAN 12AX7.

All upgrades were aimed at improving reliability and long term performance, while maintaining every last bit of the original sonic signature.

This model also features an upgraded Alps 100K stepped potentiometer offering a much better feel and channel balance for volume adjustments.

A spare lamp for the green power indicator will be included, along with a spare fuse.

Restoration Notes:

This preamp underwent a restoration focused on preserving the original character of the unit, while making it safe to operate at today’s AC mains voltages.

The power supply was completely recapped with modern discrete equivalent components with increased voltage handling. Any heat stressed resistors on the power supply board were replaced. The Zener reference diodes for the power supply voltage regulator were replaced and elevated off of the PCB. These diodes were hand selected for proper performance at operating temperatures. The thermal transfer compound for the series pass transistor was also refreshed to ensure proper heat dissipation.

The main preamp PCB was left untouched. All resistors were tested to verify that they were within tolerance.

All controls were cleaned and tested. The original volume control showed signs of out of spec channel balance and was replaced with an ARC approved Japanese Manufactured Alps Control. The Bass and Treble controls were rebuilt to address a carbon track gap issue.

All tubes are freshly installed NOS GE JAN 12AX7WA, which were carefully selected and arranged in circuit for optimal channel balance in both the phono and line stages.

Click here for a PDF copy of the SP-3A-1 Owner's Manual

The SkyFi Testing Process for Preamplifiers:

We start with a visual inspection of all internal components to make sure there are no signs of stress or aging. Capacitors are checked for telltale sings of bulging or leaking, resistors are checked for signs of overheating or cracking, and transistors are checked for signs of stress or damage. Special attention is paid to the power supply which is the most common source of failure for preamps. We then power up the unit and run a simple 1k sine wave while monitoring the low voltage output on an oscilloscope for signs of distortion or noise to get a baseline. 

At this point we will lubricate and clean all switches and potentiometers (that are not sealed) with a high quality contact cleaner, and then re-test all functions for any signs of noise or scratching. 

Final testing involves putting actual music through the preamplifier We have learned over time that some issues are only noticeable to a trained ear while listening to a familiar source material. Our test bench has reference vintage Kef speakers that we are super familiar with which will quickly reveal any discrepancies. Some preamps will then move into the listening room where they will be tested with our in-house reference system.

Technical Specifications:

Frequency response:
15Hz-30kHz, ±1dB

Distortion (THD):
0.005% at 5V out

Maximum output:
25V at 1kHz

S/N Ratio:
90dB (Aux input, no ref. level given)

Dimensions:
15 5/8" W by 5" H x 12½ D

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Thanks for looking and please click here if you’d like to receive a list of new equipment we receive weekly. We promise not to bombard you with junk email.

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PURCHASING FROM SKYFI:

This item will be professionally packaged and insured for safe transit to your home unless you opt for local pickup from our shop. Please note that all local pickup items are only wrapped with industrial strength clear cling stretch wrap if the original manufacturer packaging is unavailable.

Local pickup is available in Glen Rock, NJ, just a half hour drive from Midtown Manhattan, with convenient parking near our building.

And if you’re looking to ship to Canada, simply follow this link to view and purchase this item. We ship to Canada via UPS Worldwide Expedited service and you’re responsible for any applicable import duties and taxes.

If we don’t have the original manufacture’s packaging, we use heavy duty double-ply corrugated boxes with custom made to your item Instapak expanding foam custom inserts. In many cases this has proven to be better than the original packaging! We also use high quality fiber reinforced tape to seal our packages. Lightweight items will be bubble wrapped and shipped in a high-quality box. 

Click here for specifics on our specialized packing process that separates us from the rest.

NJ Residents or anyone picking up without a resale certificate will need to pay NJ Sales Tax.

Thanks for looking and be sure to call us at 201-879-0000 with any questions. 

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WHO WE ARE:

SkyFi Audio is a small startup business specializing in the purchase, reconditioning, and reselling of select high-end audio equipment. We only buy equipment the we admire and are passionate about. No mid-fi, no gimmicks, no junk.

Each piece of equipment is cosmetically restored and fully tested in our well-equipped lab by an engineer with 30+ years of experience in the HiFi world. If it does not meet or exceed the original manufactures specifications, it will not be sold. We are very selective about the equipment we purchase, focusing on mostly analog, high-build quality, American, and European built units.

Through our sister company which is an authorized dealer for McIntosh, Audio Research, Sonus Faber, ClearAudio, Pro-Ject Audio Systems, and Sony ES, we have access to OEM parts, service, and support. If you’re local and looking for new equipment from the above-mentioned manufacturers, please drop us a line as we can arrange both sales and professional installation in the tri-state area.

PURCHASING GUIDELINES:

We do not accept or review any offers that do not go through the official Audiogon system. We have too many items for sale and it’s nearly impossible to keep track of offers outside of the official system. Please don’t message, email, or text any offers. 

PAYMENTS:

We prefer working through PayPal which allows you to use a credit card, bank transfer, and their special financing to spread out payments over six months. We do not charge extra for any PayPal fees if you purchase the item at the asking price. You can also send us a personal check (which will need to clear before shipping), certified check, money order, or bank wire transfer. International clients without access to PayPal should use a bank wire transfer. 

If you’re picking up an item, we do not accept PayPal. You must pay in person with a certified check, bank check, or wire transfer. If you make a PayPal payment and are picking up the item, your PayPal payment will be returned. 

TRADE IN POLICY:

We accept trade-ins of equal or lesser value under certain conditions. Simply click here to submit your gear for full consideration. We will only consider high-end equipment from mainstream manufacturers such as McIntosh, Mark Levinson, Audio Research, Krell, etc. and will typically pass on displays, projectors, receivers, dated surround processors, and mid-fi equipment of any type. We will offer a fair value for your equipment, but keep in mind we’re running a business and will need to be able to resell the equipment at a profit after investing a great deal of time and resources in testing, certifying, repairing, cleaning, and packaging the incoming equipment. If you’re looking for top dollar, we suggest selling direct on your own.

SELL US YOUR GEAR (Working or Broken):

We’ll also purchase your used or broken gear and arrange pickup if you’re in our local market. Simply click here to submit your gear for full consideration.

SCHEDULING AN APPOINTMENT:                                                                                                     

We are currently operating from our shop inside our dedicated building in Glen Rock, NJ. You’re welcome to make an appointment if there’s a piece of equipment you’d like to see in operation before or after purchase. We have several well-equipped and dedicated listening areas, plus a dedicated listening studio with tons of equipment of all makes and models. We’re not a store, so please don’t make an appointment if you’re just curious as to how a speaker or piece of equipment sounds. In essence - no tire kickers please.

You can call or text 201-879-0000 with any questions or to schedule an appointment. We can also arrange to install, calibrate, and tune your newly purchased gear in your listening room if you’re local to our area. This is super useful when purchasing large speakers or heavy amplifiers. It’s also great for ensuring your new turntable is setup correctly in its final resting place.

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