• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Last stop before the end of the road !

Hi guys.

I have been off the forum for a couple of months in order to finalize some of the projects I had been drawn into. Here I will present the latest one. This is the last stop before insanity. You will realize immediately afterwards.

This amplifier is an order of one of my dearest friends. It is a two-stage design, transformer coupled of course (what else could it ever be?). This project is the last stop before the end of the road, hope to have it totally finished by end of July 2016, complete with chassis. The next project (along with the most crazy phono preamplifier ever built) will be the final before my relocation and will possess all my knowledge of building crazy amplifiers, for the most demanding audio aficionados. I really feel proud of the fact than one of my dearest friends has proposed me to build a dream power amplifier for him, where cost is of course out of question.

The characteristics of the amp are the following:

  • Two active stages only
  • Directly Heated Triodes throughout
  • Last stage built around 4C22 transmitter tube (it belongs to the team of very high impedance tubes, with an Rp reaching 5.5kOhms - my favorite tubes!)
  • Zero feedback design, with Output Transformer rating 22kOhms (!)
  • First (Input) stage built with Emission Labs 30A, anode driven, with a huge Interstage Transformer that can provide more than 68kOhms of loading conditions and unbelievable load linearity in the frequency domain
  • Both signal transformer cores are manufactured of the most exotic ferromagnetic alloy (proprietary design and manufacture as well!)
  • Double pi filter for HV of each tube
  • Oil capacitors throughout for HV of both tubes with very high capacitance
  • Mercury vapor rectifier tubes for the High Voltage supplies, with capacitor input filter, using 10 uF capacitors (do not even think of trying this, you will burn the tubes instantly)
  • Pi filter for the filaments
  • Tube rectified filament power supply for each tube, with the amazing Tungar rectifier bulbs
  • Coleman regulators for regulation of filament supplies (a must for DHT tubes)
  • Eight double c core iron pieces per tube that makes a total of 16 iron pieces per channel! Needless to mention that all of them have been wound in house
  • Total weight is expected to reach around 200 kilograms per channel
This project reflects my view of how a good sounding amplifier must be designed and manufactured. Some things in life reflect the passion of the owner and undeniably, this amplifier is among one of them.


More pictures are about to come shortly!
 

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Manufactured? I can imagine it sounds superb, but I would not let anybody near to it, including myself.

Hello from Athens!
Yes, this amplifier already sounds very good. Actually, this is the best sounding amplifier I have ever built. It might be considered as extreme (most exotic ferromagnetic alloy for sound apps, mercury vapor rectifiers, Tungar filament rectifiers, 22kOhms pri OPT, best PIO caps and electrolytics ever made, etc) but since I am the man behind every aspect of this project (calculation, design and manufacture of all the iron pieces), I know the maximum potential and how far the performance index can be raised.

This amp reflects my knowledge of building exotic audio amplifiers but there is still some room for improvement. It is equipped with 16 iron pieces per monoblock. The next project will be initiated during July, and will be the end of the road of Single Ended Triode amplification, with 3 active stages and 28 iron pieces per monoblock.

Stay tuned for the most insane amplifier you have ever experienced!
 
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Impressive indeed! Which speakers are you intending to use the amplifier with?

Goodmorning from Athens!
The speakers that I am going to use are Altec VOTT, early version 515 & 288, with JBL 175 tweeter, all transformed to field coil units.
The strange thing here is that all the drivers will be equipped with very high voltage power supplies. Forget those 12V supplies... And those 200 volts... They will be powered at around 500-550 volts at least.
As you understand, working with very high voltages is my passion. I have managed to accommodate things easily and safely, they are not dangerous at all, unless you intend to commit suicide.
 
Can you please give more info about the actual tungar rectifier?
I have btw tried the 30a As driver for ux-250 . Very nice driver tube imho
Nice and heavy looks promising

Helo from Athens Greece!
This tungar rectifier is a clone of GE 189049,draws approximately 17A at 2.2V and here it powers the filaments of both 30A and power tube. Its application in filament ignition is a very strong upgrade in sound quality. You can find 189049 NOS NIB at around 160 USD per piece. Strongly recommended!
Years ago I had tried 30a driving Marathon 210 mesh. That sound was the best I had experienced. Telefunken RV258 was quite close but not better. Now, with this hard core transmitter, is the only time the performance of 210 mesh is left behind. The sound is spectacular, unbelievable, even at my standards.
In about two weeks from now this project will have been finalized, I am waiting several hundred kilograms of the most exotic ferromagnetic material for audio transformers, cut c pieces of course. I will start winding and hope that by end of August I will have posted here the first results. This amp will be the end of the road in Single Ended Triode amplification. I cannot see the time to listen to it.
Under any circumstances, the EML30A tube is highly recommended!