Ampex 351 Preamp Pair

Sequentially numbered pair of Ampex 351 valve/tube preamps for sale.

It’s unusual to find a pair like this restored to a high standard. They only work together as a pair (the first controls the second).

Extensive work has been undertaken to produce these excellent standalone preamps.

Detailed information on the work completed by Thump NYC:

• Replaced all electrolytics
• Replaced all passives that commonly leak DC
• Replaced all power resistors
• Replaced any other resistors or otherwise out of spec components
• Re-tension tube sockets
• Cleaned all mechanicals including every edge crimp connection
• New #47 lamps
• Assemble / Test / Burn in

When restoring our Ampex 351s, we began with replacing all electrolytics throughout the circuit. Every single component is changed on the power supply board to insure the circuit is fed exactly what it was intended to receive. This includes all passives (resistors and ceramics) and actives. A common failure point on these units is the old selenium rectifier for the DC heater supply. This too is pulled from the unit and replaced with a pair of 5402 diodes and dropping resistors to provide a perfect 12.6 Vdc heater supply in the circuit. Once our blanket parts swap is complete we clean every interconnecting point within each unit and resolder weak traces to make sure there is no fear for intermittent edge card crimp connections. We tighten all hardware and clean all mechanicals until the unit feels good to operate. The unit is then brought up on a variac slowly to help form the new capacitors and all power is checked over throughout the circuit. Tubes are loaded and power is checked again. Mic check, we’ve got another Ampex!

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This item is located in the USA. The listing excludes tax, which may be payable depending on your location. If you have any questions, please get in touch and we will do our best to help.

SHIPPING: Worldwide shipping available. Brokerage sale so shipping is arranged between the buyer and seller direct (but we can usually help with access to trusted couriers etc). If you need an estimate then get in touch.

Brokerage Sale Information:

Brokerage sale on behalf of a client. If you have gear that you want us to look at selling on your behalf then please look at our Commission & Consignment page for more information and get in touch to discuss your requirements.

This item is located with our trusted techs in NYC. We only sell items by brokerage with trusted clients who understand their gear. That said, it is the buyer’s responsibility to confirm details provided in the listing by the seller are to their satisfaction – if you have any questions at all please let us know before we arrange shipping.

As a brokerage sale, payment will be made to us but will be held in escrow for the seller until the buyer confirms satisfactory receipt of the item. The buyer has 14 days from receipt to raise any concerns, after which we will release funds to the seller. Full terms available on request.