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2x Philips Ha1x tube microphone preamps/program amplifiers | JS 1345/2 input trafos | Read info.

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Shipped From
Olle's shop
Gothenburg, Sweden
Joined Reverb

About This Listing

Up for sale is a very nice pair of Philips Ha1x tube microphone preamplifiers (also utilized as program amplifiers) from the mid 1950's. The amplifiers are very similar to the Philips Ha16 (see photos) used by the Swedish Broadcasting Corporation for all kinds of duties, except these use a pair of EL84/6BQ5's instead of a pair of E81L's on the output.

The input is dual grid, meaning the amplifier is fully differential. The input transformers -  1345/2 -  are made by the well-renowned Danish manufacturer Jørgen Schou, commonly referred to as JS. The transformers feature a 50 and 200 ohm primary and a 15k or 60k secondary. The units are wired for 200 ohms to 60k to achieve approximately 60dB of gain.
There's no way to control gain and this is how it was done back then. Instead, you'd attenuate either the input or output. I can include two dual 600 ohm pots in the sale. You can also pick up some nice dual 600 ohm attenuators from Hairball and other suppliers.

The output transformers are made by Philips. They're really sturdy, capable to push several watts, housed in a nice mu-metal housing to eliminate RF and electromagnetic interference. Secondary is 600 ohms and primary around 6k. They also have a (~15 ohm) feedback winding, which you can tamper with to squeeze more out of the amps, but I'd recommend to leave them as-is.

Note: these are not power amps, which is a common misconception of vintage circuits utilizing more "capable" output power tubes. These, like the Ha16 (see photos), were designed for universal use.

The amps sounds very warm and lush and they're extremely quiet due to the differential push-pull circuit. Much more so than any single-ended preamp I've ever used, regardless of PSU. These are perfect for ribbon microphones, for which they were designed back then.

There's one EF86 for each input section. Currently there's two NOS Philips script logo EF86's in each. The NOS EL84 output tubes are also made by Philips.

. .
This is what's needed: a 250VDC and 6,3V (AC or DC) power supply. The current draw is approximately 40mA (per unit). Regarding the heaters, I would recommend not to go under 2A, even though each EL84 only draws 600mA at a maximum which - including the EF86 heaters - sums up to less than 2 amperes.

* You 'll also - for safety reasons - need a suitable rack. These actually fits sideways on 2U 19" rack panels if you only come up with a way to mount them. Otherwise, install them in a larger chassis.
* NOTE: The Tuchel input connectors was not installed when I took the photos a while back. They are now.

* The amps weigh around 4 kilos each, which means shipping is gonna be around $60-75 depending on your location. USA=approximately $107.

* Offers are welcome!

This item is sold As-Described

This item is sold As-Described and cannot be returned unless it arrives in a condition different from how it was described or photographed. Items must be returned in original, as-shipped condition with all original packaging.

Product Specs

Listed12 days ago
ConditionExcellent (Used)
Excellent items are almost entirely free from blemishes and other visual defects and have been played or used with the utmost care.learn more
Made In
  • Sweden

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