Deathbringer 211 Tube Amplifier
|National Union 6B4G - clear and smoke glass|
|Zu Audio Soul Superfly Loudspeakers|
Note: if customers want to build 212 now, we will be delighted to help you with it.
|212-D Vacuum Tube|
|NOS 212-D Valve|
|WE 418A Tube|
|WE 417A Tube|
An additional stage gives us the flexibility to tune the sound with different tubes too, to add more body and warmth to the overall sonic signature.
|3 stage tube amplifier|
Continuous carbon brush pots (bad channel matching, bad for stereo imaging, causes shifting of imaging and fuzziness) are ancient technology that should be discontinued usage for very high end amplifier like this.
|128 step volume control|
A good interstage is efficient (>90% signal transfer rate) – having minimal signal loss, and isolates the stages from each other, and provide good DC current drive to the grid when it is needed, which capacitor coupled design could not do.
So, interstage is the only way to go, with active cathode bias to lock the tube at their designated operating point until end of life.
|Interstage Coupled Tube Amp|
|Direct Coupled Tube Amp|
There are plenty of NOS Telefunken EL803s is available, with some variants of more normal EL83 and EL803 in the market. If EL803s was a commercially used tubes with big name tube amplifiers, it would have cost over U$500-1K per pair. You are getting absolute premium quality NOS Telefunken EL803s at a very decent price. Cheaper than a brand new driver tube from recent tube manufacturers.
|Telefunken EL803S with Falcon logo|
Still, with our 16K high impedance OPT and unique operating point, class A2 comes as a bonus, and valued reserves when power is called for, and can deliver as high as 31W. 845 is another good candidate, with higher output power and lower Rp, but NOS 845 is almost impossible to find, and with much higher price than the 211. 845 has more power and authority (darker sounding) compared to 211. 211 wins in terms of resolution and finesse, and has a more balanced and livelier character.
Note: for those that requires class A2 operation constantly, a bigger driver tube, such as EL84, 6L6 or EL34 would be recommended to deliver even MORE current drive to the grid of 211. This would require a bigger interstage though, and the specifications (soundwise will be slightly inferior for the golden ears, for tin ears like mine, these 2 would sound the same) may not be as good as a small interstage. You get some, you loose some. The world is fair.
|RCA 845 Tube|
|GE VT4C - 211 Tube|
The filament is 4V 2A, and therefore have plenty of choices around for tube rolling due to the low voltage and low current B+ demand for these stages.
|Cossor 43IU Tube|
|Telefunken RGN2004 Rectifier|
This also reduces the importance of matched tubes – tubes are not dynamically matched and it ages differently over time, which negates the effects of matching at the first place. Tube matching – a myth? Go figure.
|Constant Current Sink and Source|
|Cathode Bias / Fixed Bias|
I have discussed the 211 operating points previously when I talk about our high primary impedance output transformer impact on amplifier design. You can use that as a starting point and go from there. There shall be tuning needed after actual implementation for fine performance tuning.
Actual measured output power = to be determined when unit is built, and when different tubes are tested.
|211 Operating Point|
|6SN7 operating point|
|Sanyo Os-Con caps|
|Sikorel Capacitor in action|
|Siemen Sikorel Capacitor|
|Sikorel Capacitor Specs|
Imagine having these parameters for a 40UF/900V capacitor: Ipeak = 800A, Irms = 17A, ESR = 5m Ohm, response 40V/us. Below is a snippet of the general features. This capacitor will be deployed on the 1st 2 stages of the CLCLC filter to filter all the gremlins (ripple/noise) after the tube rectification. The high voltage tolerance makes it easy for not needing to series too many capacitors to meet the Vdc requirements.
The highest temperature it can tolerate is 105 degC and still, the DC tolerance is 650Vdc, which when put in series, is still over the B+ of 1290Vdc (1300Vdc). Did I mention that the useful life is 100,000 hours at 70 degC?
|Secret 211 B+ PSU Capacitor|
These are no normal electrolytics too. Look at their specs. We like them for the sound, but they themselves are no ordinary peasants. Ultra long life, low ESR, high durability, high temperature tolerance, and etc. Look at the specs below! Did I see 90,000 hours of useful life? That is 63 years of use if you play it for 4 hours a day.
|Vishay Electrolytic Capacitor|
|Philips BC Electrolytic Capacitor|
|211 Tube Socket|
|High quality 211 tube socket|
|Teflon 8 pin socket|
|Teflon 5 pin socket|
|RGN2004 Tube Socket|
|8 pin teflon socket|
We take special care in selecting the resistors use - one is for safety reasons where right voltage and wattage tolerance are strictly observed for SAFETY (most importantly), and sound, and lastly - long life operation. We design the gear to work for a very long, long service life. Let's take a look below:
Signal / cathode bias / low voltage power supply resistors – Riken RM carbon film resistors, for tone and body. Carbon film resistors are noisy no doubt but they produce the tone and body that other resistors could not do. Open up those legendary vintage amplifiers and you will find carbon film resistors all over them, on top of the oil capacitors that are very famous in the older days. With the right usage/applications and over-sizing, carbon film is an excellent choice for tube amplifier building, especially used in the signal section.
|Kamaya Carbon Film resistor|
|Carbon Film Resistor|
|Carbon Film Resistor|
|Riken RM-2 Resistor|
|Riken Carbon Comp Resistor|
|Panasonic 561 Resistor|
|Vishay Sfernice Resistor|
|Vishay Enamelled Wirewound Power Resistors|
|Koa Metal Oxide Film Resistors - high voltage|
|KOA metal oxide film resistors|
|Precision Wirewound Resistors|
Transformers (Z11, Super Hi-B, NanoCrystalline, Hybrid Permalloy)
Types of core materials are very important for transformers making, be it a power transformer, choke, interstage or output transformer. If you have not used any high quality cores for your transformers, it is your great loss. They run more efficiently, saving you tonnes of energy (energy bills), they produce less heat, they last many times longer, and they sound much better!
What comes next will be the winding method. Safety and sound come first. Rubbish (you know what I mean) winding method will fail in a very short service time, and is unsafe - fire and electric hazard. With the correct winding method, safety is given, and transformer performance will be optimized and sound or power quality will be a sure thing. We have talked a lot in our blog on transformers and shall not touch so much here.
|High Voltage Full Wave Rectification|
|Choke Input Full Wave Rectification|
Note: Above design utilizes 2-coil choke in differential mode to reduce noise further. The effects are much better than normal single coil choke alone.
|Ultra Responsive High Voltage B+ PSU|
|B+ PSU for gain / driver stage|
5/30/2016 - added additional graphs on the PSU. I doubled the load at 2s and you can see that the power supply recovered to the steady state in <0.5s. That's what a real dynamic PSU should behave. If it takes >1s to recover, you know it is going to be sloppy. Using the most expensive audiophile capacitor will not help you here if it is fundamentally wrongly designed.
Preamplifiers, maybe, but not necessary if you know what you are doing. One can hardly hear hum on our preamplifiers or power amplifiers with volume turned to maximum and ears next to the speaker drivers for our high end version. Some low end versions may sacrifice some to get decent sound over minimal acceptable hum (only audible when ears are next to the speaker drivers).
Usually our chassis will be made of Myanmar solid black ebony wood, which is one of the hardest and densest wood available for audio use. The usual wood thickness will be 20mm for the base, and thicker upon user request. For finishing, we usually do not use lacquer or paint, but with wood wax or oil to keep the wood alive and reduce chemical poisoning.
|Hardwood Tube Amp Chassis|
|Solid Wood Tube Amp Chassis|
|Wood Valve Amp Chassis|
|Relay 128 step volume control|
- Shipping case is a must for overseas shipment. We have professionally made studio equipment cases, used for professional studio equipment, for purchase with the purchase of our gears.
- Some of you may not agree with what we practise, that we totally understand. It is a matter of taste and personal beliefs. Let's keep personal opinions to ourselves and do not argue over it. PEACE.
- Our design methodology may change depending on usage and final goal of the designated gear.