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Sunday, May 25, 2014

Tube of the Month : The 1616


Some people noticed the rather unusual rectifiers which I had in one set of the 211/211 amplifiers displayed at the recent High End fair in Munich. While the amps which were playing most of the time used 836 vacuum rectifiers, the set which was on display had the 1616 plugged in.

The 1616 is a half wave rectifier developed for transmitting applications. Half wave means it contains a single diode in the envelope. So two of them are needed for a full wave rectifier with center tapped mains transformer. Or four for a full wave bridge.

The 1616 has an UX4 base and medium metal cap for the plate connection. It has the same pinout as the 836 and 866A. Only two of the base pins are used for the filament connection. The other two are unused. It has the same filament requirement as the aforementioned two tubes: 2.5V at a hefty 5A. The latter is probably the reason why this rectifier is widely ignored by audio amplifier designers. Although it's other parameters are more than suitable for most audio power supply requirements. It can withstand a peak inverse voltage of 5kV and deliver 130mA per tube. The peak inverse voltage rating is similar to that of the 836 but only half that of the 866A. The 836 and 866A can deliver twice the current.

But since most audio amps will not get close to those limits, the 1616 is a good alternative, especially to the mercury vapour 866A. The 1616 is  vacuum rectifier which does not have the hazards of mercury spill in case of glass breakage. The 1616 has a higher voltage drop though. For initial tests of power supplies which are intended to work with the 866A the 1616 is perfect. While the 836 and 866A come in the coke bottle shape, the 1616 was made with a straight sided bulb. It has a similar impressive size than those two and while the straight sided glass seems less attractive at first glance, it has it's own kind of beauty. Since it is hardly used any more it can be found at low prices.

Pictured above is a RCA 1616 produced for the military. Hence packaged in the rather bland JAN boxes:

These have a graphite plate structure:

View from the side:

Another shot showing the graphite plate:

Metal plate versions have also been made (shown on the right):

Close up of a metal plate 1616:

The base:

Two 1616 in operation in a PSU:

Close up of one of the tubes:

The filaments are actually rather wide ribbons, as commonly used in directly heated rectifiers:

Zooming in:

A great rectifier, especially for amps which use transmitting triodes.

Best regards


Saturday, May 17, 2014

High End 2014 : The Room


The second day of the High End is over. Here a few impressions of the room which I set up with Bernd Hemmen of PrimaryControl and Wolf von Langa.

The entrance to our room:

Some posters on the back wall:

The speakers and power amps:

The rest of the system:

The line stage:

The phono preamplifier:

The turntable:

A Lyra Atlas cartridge is used, mounted on one of Bernd's beautiful tonearms:

Bernd has a couple more tonearms on display:

This is his top of the line model:

A close up:

Check out this gorgeous finish:

The 211/211 amps:

Another set on display:

This 300B amp also only has been on display so far:

We might hook them up during the remaining two days.

Some more stuff on display:

Some more photos of Wolf's speakers:

Crossover and field coil supplies are hidden in the base:

Check out the detailed finish on those drivers:

Best regards


Friday, May 16, 2014

High End 2014 : Silbatone


Here some impressions from the Silbatone room:

This years they brought Western electric 12a and 13a horns.

These beauties were made 1926!

All the precision woodwork was done without CNC machines:

An impression of the sound:

Best regards


Thursday, May 15, 2014

High End 2014 : Azzolina Audio


Azzolina Audio exhibits at the Munich High End for the first time this year. They brought some beautiful horn speakers.

I had the pleasure to borrow a set of 801A/801A amplifiers to them along with a 10Y line preamp.

This is the sound of their set up:

Check them out in Booth H13, Hall 3 at the fair.

Best regards