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Monday, February 26, 2018

The 46 drives 46 Amplifiers - Part 2


In part 1 about these new mono blocks I showed some initial assembly steps and gave a hint how the final amps will look like. In the meantime the pair is finished.

The set consists of two chassis, one per mono block.

Two stage, a 46 driving another 46 through an interstage transformer.

The 4 rectifiers in the back are a full wave bridge using 4 TV damper tubes into a choke filtered supply.

Here some more photos of the assembly process:

The top plate with all parts mounted and wired up on the underside shown above. Then the next level is mounted underneath:

And the final level contains the power transformers and DC filament supplies. Unfortunately I forgot to take a photo with the last module mounted since I was eager to finish and test the amp.

One of the amps in operation.

Now of course the question 'how do they sound?'

People who read my blog regularly know that I am reluctant to provide subjective sound descriptions. Especially of my own creations.

But these amps really surprised me. The previous, simpler builds of 46 amps were already stunning. But these are simply outstanding.

The 46 has a very special character which draws you into the music. It simply does everything right.

Sometimes more of a good thing can be too much, so the question was would a 46 drive 46 amp provide too much '46ness'?

These amps prove that the concept works. It brings everything to the next level. I can say with confidence that these are probably the best sounding amps I built so far, although they are not even using silver transformers as my other top of the line amps. But there is a caveat.

1.25w is all you get from a 46, yes just 1250 milliwatts.

With the right speakers those are the most glorious milliwatts.


Now the question is what would  an all silver version of these amps sound like?

Needless to say I am very happy how these turned out. Since these monos will be shipped to their owner soon, I already ordered the chassis materials for another pair for myself.

Best regards


Wednesday, February 21, 2018

The Octal Preamplifier


since I mostly write about my separate phono and linestages, many people are not aware that I also have a full function preamp in the offering which has a phono stage integrated. The Octal Preamplifier.

The Octal Preamp has a transformer coupled lien stage with auto former volume control. In this Mk2 version the linestage uses the 6AH4 triode.

The phono section is a LC coupled circuit with passive split RC RIAA.

6SC7 is used as input tube and 6N7 in the second stage.

Signal section and power supply are in separate chassis.

In this case the preamp is built in the classic landscape chassis but could be done in portrait stye as well.

A lower cost alternative to my D3A and 10Y combo.

Best regards


Friday, February 16, 2018

Custom Line Preamplifier


A while back in a post about a set of custom 300B amplifiers I showed the kind of adaptation which is possible to my regular designs. Here is a custom line preamp which will be used with those 300B monos.

The concept is based on my 10Y linestage but with different transformers, in this case a set of line output transformers supplied by Monolith Magnetics.

For volume control Sowter TVCs have been chosen which allow some additional gain which in this case is used for separate balance adjustments.

The knobs which are different style from my usual ones were also customer supplied.

The power supply comes in a separate chassis.

The PSU uses a 5U4G full wave rectifier tube. the switches on the PSU allow some adjustment of the filament voltage which can be monitored through the jacks in front of the tube sockets on the line stage.

While I usually offer a variety of options, such special requests can also be fulfilled.

Best regards


Monday, February 12, 2018

The 46 drives 46 Amplifiers - Part 1


After the excellent sound achieved with the 46 amplifiers I built so far, I always wanted to make a more elaborated one with a second 46 as driver tube.

Finally somebody commissioned a set of mono blocks with this configuration. Here are some first photos of the initial construction steps.

The top plate only has the tubes exposed on the top. the two 46 and a row of 4 6AX4 or similar TV damper tubes for a full wave bridge rectifier. some components are directly mounted on the underside of the top plate for short signal paths:

This is how the top will look like with the tubes plugged in:

The amp will be constructed in the tower style similar to the recently finished 845 monos.

As in those the parts are mounted on separate sub modules which get stacked inside the chassis. Above the filter section of the high voltage supply, filament chokes (all filaments will be DC) and the Tango output transformer. The power supply section, with main B+ transformer and separate filament supplies for the two 46:

Stay tuned for updates as the construction of these progresses!

Best regards


Thursday, February 8, 2018

News from the ELROG Tube Factory 9


It's been quite a while since I published an update about the Elrog tubes. We had been busy catching up with orders and with the development of the new tube types.

The development of the ER50 and ER801A took more effort than expected. I am happy to announce that we have first functional prototypes.

It's always the details which cause throwbacks. What first seemed like a rather straight forward job by making the necessary adaptions to the 300B design, ended up in a complete redesign of the entire structure.

But it was worth it! The first 801A prototypes are shown in the pictures. amplification factor is a bit low but will be adjusted to reach the target value in production.

The filament spec is spot on at 7.5V/1.2A.

Some of the lessons learned from this development will also be used to improve the existing 300B design.

Here a screen shot of the prototype on the curve tracer:

It turned out as linear as a DHT can get. Exactly what we wanted to achieve. But what about the sound? Can it compete with the old production tubes?

First test in a linestage:

I am always reluctant with sound descriptions. All I can say is that I am very happy. Immediate emotional impact with the prototype tubes which are not even properly burned in. Unbelievably transparent and detailed.

Similar results in my 801A drives 801A power amps.

We will now make the first batch. It will take a couple weeks until they are finished, burned in, tested and printed. Then those who preordered will receive their tubes.

And now a few impressions from the production floor. Here we see a 300B on the sealing station. Here the glass bottom gets sealed to the tube.

These video clips show the process, here we see the internals getting inserted into the glass tube:

The sealing:

Then the tubes go onto the vacuum pump:

They are evacuated over night with the lid down and heated to a high temperature to drive all gasses out.

An ER242 fresh from the vacuum pump and powered for the first time:

ER845s in the burn in station:

Stay tuned for further updates from the production floor.

Best regards