Message Board - AMPEX Model 351 General Discussion
NOS Ampex 351 Input Transformer, tape machine. Free shipping. Or Best Offer. Ampex 350 351 Reel To Reel Tape Recorder Remote. These Ampex plug-in transformers are used for the input electronics of Ampex tape recorders, specifically Models AG-440B, AG-445B, along with the 500 and 600 series. They were used in place of a dummy plug to provide a Balanced Input to the Record/Play Electronics. They use a standard Keyed Octal plug with gold plated pins. A tube mic pre requires an input transformer to work well with modern low impedance microphones. In vintage tube mic pres this transformer frequently plugs into an octal socket like the ones used for large power tubes. Here's the empty socket from an Ampex 601 that came in for a recapping job: Good quality input transformers don't come cheap.
- Input and interstage: 1:1+1: 0: 410 Ohms +30 Dbu: K Style options: Buy: 9905: Federal AM864/U Compressor WW Primary 120,110 V Twin winding 50/60 Hz. 175-0-175 at 40 mA, 6.3 at 2 A 5V at 2 A. Internal electrostatic shield See also input type 8540, output type 9900 and choke type CB24. I Shrouded: TRANSFORMERS FOR VINTAGE MICROPHONE.
- Ampex plug-in Input Transformers For recording from an unbalanced line, the dummy plugs (4030034-30) are used. These dummy plugs jumper pins 3 and 4, pins 6 and 7 and pins 2 and 8 (these two pins also connect to ground and the dummy plug shield). For balanced line recording, two input transformers are available to replace the dummy plugs.
The AMPEX Series 351 Magnetic Tape Recorder/Reproducers are high quality precision instruments designed for the professional user who requires the finest and most faithful recording and reproduction.
A basic recorder/reproducer in the 351 series consists of a tape transport for operation at tape speed pairs of 3-3/4 inches per second (ips) and 7-1/2 ips or 7-1/2 and 15 ips, a head assembly for use with l/4-lnch magnetic tape, and an electronic assembly which contains the record amplifier, reproduce amplifier, bias and erase oscillator, and power supply — all featuring etched board construction.
Head assemblies for either full (single) track, half track or two track stereophonic (351-2) operation are available. CCIR equalization can be obtained on request when ordering equipment.
Several mounting arrangements are offered - console, two case portable and rack mount. In the portable equipment, one case contains the tape transport and the other houses the electronic assembly unit.
The 351 Series recorder/reproducers are available for full (single) track, half track or two track stereophonic operation. All operating controls are located on the tape transport with the exception of the record control which is on the front panel of the electronic assembly.
When the remote control unit is fiimished, duplicate tape motion controls, a RECORD button and RECORD INDICATOR light and a TAPE MOTION indicator light are mounted on the remote unit.
The equipment can handle the NAB 10-1/2 inch diameter tape reels or the EIA 5 and 7-inch reels. Provision is made for selection of proper tape tensioning at the REEL SIZE switch on the tape transport for the LARGE or SMALL size reels.
Either of two capstan drive motor speeds can be selected at the LOW-HIGH TAPE SPEED switch which is also on the tape transport.
On the front panel of the electronic assembly are facilities for setting RECORD LEVEL and (reproduce) PLAYBACK LEVEL, selecting LOW SPEED or HIGH SPEED EQUAUZATION, selecting three input arrangements by means of the INPUT TRANSFER SWITCH, and switching the vu meter at the METER and OUTPUT switch so that (reproduce) PLAYBACK, RECORD, BIAS and ERASE LEVEL(S) can be read. A phone jack (PHONES) for monitoring, a RECORD button, a RECORD INDICATOR light, and a POWER OFF-ON switch are also mounted on the electronic assembly front panel.
Another MONITOR AMPLIFIER phone jack and a line termination (LINE TERM) OFF-ON switch are located on the back of the amplifier-chassis.
Foundational text courtesy of the AMPEX Model 351 operation and service literature.
Ampex 351-2 fully restored by Steve Puntolillo of Sonicraft A2DX - Photo courtesy of Steve Puntolillo
AMPEX 351 Tape Machine assortment
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Ampex Model 351 Tape Machine
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Early Ampex 4 track 1/2 inch Machine
I have had this machine since about 1982 when I worked in Abbey Road (EMI Studios). I know that Abbey Road did not prefer to use Ampex for various reasons …
I have had this machine since about 1982 when I worked in Abbey Road (EMI Studios). I know that Abbey Road did not prefer to use Ampex for various reasons …
Ampex 351
Thank you for wonderful site. I been collecting tube tape recorders for years Currently have around 300 from different countries Ampex is my favorite …
Thank you for wonderful site. I been collecting tube tape recorders for years Currently have around 300 from different countries Ampex is my favorite …
The Finest Recorder of its Time
Over 50 years ago, while a student at Columbia University, I joined the college radio station, WKCR-FM, serving as both recording and broadcast engineer, …
Over 50 years ago, while a student at Columbia University, I joined the college radio station, WKCR-FM, serving as both recording and broadcast engineer, …
Ampex 351. A true member of the family. Not rated yet
So back in the early eighties, my father was working in a recording studio in London. Never found out why he was there! Anyway, a mobile studio was being …
So back in the early eighties, my father was working in a recording studio in London. Never found out why he was there! Anyway, a mobile studio was being …
Chief Engineer/Derek Studios Not rated yet
The first serious 2 track machine I bought for use in my new studio was an Ampex 354. In those days I was using the machine for mixdown using Ampex 406 …
The first serious 2 track machine I bought for use in my new studio was an Ampex 354. In those days I was using the machine for mixdown using Ampex 406 …
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![Ampex 351 input transformer diagram Ampex 351 input transformer diagram](https://i.ebayimg.com/images/g/cNoAAOSwzs5fCaMg/s-l640.jpg)
Good quality input transformers don't come cheap. If this socket is empty, think of spending just shy of $100 to put a transformer in there. Here's what the socket looked like in this unit when it came to me:
That's how the input transformer plugs into the socket. Here's the base of the part that came in this Ampex:
Ampex 351 Schematic
The base looks just like an octal power tube and it plugs in in the same way. Let's look a little closer at this one. Here is the piece standing on it's base:Here I've popped off the metal shield so you can see the transformer windings: