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Wednesday, October 27, 2021

Tube of the Month : The 5Z3


After the recent introduction of the ELROG ER5Z3, I thought it is a good idea to pick the 5Z3 as tube of the month.

The 5Z3 is a directly heated full wave rectifier. It is electrically identical to the 5U4 but has a different base.

While the 5U4 comes with a 8 pin Octal base (of which 4 pins are not used) the 5Z3 is the same tube on a 4 pin UX4 base. The pinout is shown on the left. Both tubes have a 5V filament which consumes 3A. They have the same maximum ratings and characteristics. See the RCA data sheet for all technical details. The 5Z3 is a member of a small family of 3 tubes which share the same electrical characteristics and only differ in the base. The third one is the 5X4 which has the same base as the 5U4 but a different pinout. While the 5U4 has seen a widespread use and still is used a lot in current production amplifiers, the 5Z3 and 5X4 were less popular and are rarely used nowadays. Let's have a look at some 5Z3 rectifiers from different manufacturers, starting with RCA:

Another RCA 5Z3 made for the military:

The military designation of the 5Z3 is VT-145

Next we have a National Union 5Z3:


And lastly the ELROG ER5Z3, the only current production 5Z3 I am aware of:

Best regards


Sunday, October 17, 2021

10Y Line Preamplifier in Tower Chassis


Here some photos of a 10Y preamplifier in floor standing tower chassis.

Some years ago a customer commissioned a 10Y linestage in tower chassis, but this time I was asked to do a single chassis version with the power supply integrated.

It took some trickery to arrange everything inside without causing any hum issues.

Everything turned out fine and it performs the same as the 2 chassis portrait version.

Some photos of the preamp glowing in the dark:

If you are interested in your own 10Y line preamplifier drop me an email.

Best regards


Friday, October 8, 2021

The ELROG ER5Z3 Rectifier Tube


Yet another addition to the ELROG family, the ER5Z3!

Admittedly this was an easy one since the 5Z3 is electrically equivalent to the 5U4 except that it has a 4 pin UX4 base.

After the introduction of the ER5U4G, it was a small step to add this tube to the portfolio.

Best regards


Monday, October 4, 2021

Stereo Single Ended 45 amplifier


below some photos of a recently finished 45 amp.

It is a stereo amplifier with the power supply integrated.

This represents my entry level in amplification with the 45 tube.

Tube rectification with two 6AX4 TV damper tubes. A pair of 6N7 as driver tubes is interstage transformer coupled to the output tubes.

All transformers and chokes, except the main power transformer reside inside the chassis.

The two trim pots between the output tubes are hum buckers to minimise residual hum from the AC heated 45s.

This enables a hum free operation except on extremely sensitive speakers for which I would recommend the DC heated version of the 45 amps. On my 98dB speakers no hum whatsoever was audible.

Best regards