jamato8
Headphoneus Supremus
Woo3: I could not help myself, I have to modify.
This amp is really singing now. It is hard for me to keep my hands off of anything, even if it appears that there is little to be done, but even before I got the Woo3, I knew it would be a good, though small, platform to work with. Out of the box this is a rewarding and enjoyable auditory experience. The price belies the value you are receiving. This amp is dimensional, tonally very musical, i.e.: as in real music. Within 24 hours of receiving the unit I had to pop it open and look around.
Inside it is well laid out with Teflon wiring and very clean and shiny solder. The capacitors are photoflash, which I don’t see commercial producers of audio equipment using very often but are reputed to work very well in a power supply application, which they are here. The supply for the 6080/6AS7 and the drive tubes the 6922, use the photoflash capacitors for the B+. The rest of the parts are of good quality but you won’t find any boutique parts here nor should you expect to (they are often overrated anyway).
So why modify? Because I must.
First off I noticed that the input to the 6922 has a dc blocking capacitor. This used to be popular but most sources do not put out dc on the signal. This capacitor is only going to degrade the signal, even if slightly. The easy fix for this is to just move the wire from the volume control to the other side of the capacitor, which bypasses it. I also noted that the bias for the tube on pin 8 is set at 1.4 volts. This is a common bias for a 6922/6DJ8. A resistor, unbypassed by a capacitor (I normally use a 470uF cap in conjunction with the resistor, which increases bass response but can also add its own color) is used. My preference is a NiMH battery for bias on signal tubes. I have compared this head to head with a resistor, resistor with a Black Gate capacitor and other battery types and the NiMH is by far the best and relatively inexpensive compared to the Black Gate capacitor, that I preferred to using only a resistor. The NiMH will remain charged by the current on the cathode and will trickle charge. The battery will settle to around 1.35 volts, which is fine for the application and should last 5 to 7 years.
Now to the power supply. There is a photoflash capacitor for each of the 6922 tubes and for the B+ going to 6080, which will also go on to feed the plates of the 6922 tubes. I used 15uF Solen Fast Caps bypassed with a .01uF polypropylene SBE 716 for the photoflash going to the 6922 and a 12uF for the B+ going to the 6080 also bypassed. I cannot stand the sound of Solen capacitors unless bypassed. Once bypassed they loose the grainy quality they can impart to the sound.
The batteries and capacitors are held in place with nylon ties secured to a sticky sided mounting made for this purpose. I have also noticed that there is a grid stopper on the input tube after the volume control. But for some reason it has a very long leg to the pin of the tube. These should be mounted as close as possible to the pin in order to avoid picking up any signal that they are trying to get rid of in the first place. These will be replaced with some nice 1 watt nos tantalum 220 ohm resistors that I have on hand.
Now to the sound of these changes.
After the above change and as the hours went by, the amp opened up more and more. Layering increased with the recording space being reproduced in a more and more convincing manner. I was listening to Diana Krall, “All For You”, noticing the subtle changes in her voice and her palpable presence. Saxophone on my jazz recordings has a throaty and tangible quality. I have also noted that the depth and width of the recording landscape increased, much to my listening pleasure. Bass impact has increased and the perception of “speed” in the leading edge of notes and of the plucked string gained in realism and tightness.
Noting the above changes, I wish to state that the stock Woo3 is excellent and within the constraints of its price an exceptional buy. I find that the visual presentation in fit and finish to show no compromise. That some small changes can add to the musical enjoyment, for me, only goes to show what a good design it is to begin with.
Woo3 with Amperex PQ 6DJ8 gold pin, WE 421A
The heart of the tube, the heater.
Added caps and resistor changes.
Non inductive high quality resistors in the power supply.
John
This amp is really singing now. It is hard for me to keep my hands off of anything, even if it appears that there is little to be done, but even before I got the Woo3, I knew it would be a good, though small, platform to work with. Out of the box this is a rewarding and enjoyable auditory experience. The price belies the value you are receiving. This amp is dimensional, tonally very musical, i.e.: as in real music. Within 24 hours of receiving the unit I had to pop it open and look around.
Inside it is well laid out with Teflon wiring and very clean and shiny solder. The capacitors are photoflash, which I don’t see commercial producers of audio equipment using very often but are reputed to work very well in a power supply application, which they are here. The supply for the 6080/6AS7 and the drive tubes the 6922, use the photoflash capacitors for the B+. The rest of the parts are of good quality but you won’t find any boutique parts here nor should you expect to (they are often overrated anyway).
So why modify? Because I must.
First off I noticed that the input to the 6922 has a dc blocking capacitor. This used to be popular but most sources do not put out dc on the signal. This capacitor is only going to degrade the signal, even if slightly. The easy fix for this is to just move the wire from the volume control to the other side of the capacitor, which bypasses it. I also noted that the bias for the tube on pin 8 is set at 1.4 volts. This is a common bias for a 6922/6DJ8. A resistor, unbypassed by a capacitor (I normally use a 470uF cap in conjunction with the resistor, which increases bass response but can also add its own color) is used. My preference is a NiMH battery for bias on signal tubes. I have compared this head to head with a resistor, resistor with a Black Gate capacitor and other battery types and the NiMH is by far the best and relatively inexpensive compared to the Black Gate capacitor, that I preferred to using only a resistor. The NiMH will remain charged by the current on the cathode and will trickle charge. The battery will settle to around 1.35 volts, which is fine for the application and should last 5 to 7 years.
Now to the power supply. There is a photoflash capacitor for each of the 6922 tubes and for the B+ going to 6080, which will also go on to feed the plates of the 6922 tubes. I used 15uF Solen Fast Caps bypassed with a .01uF polypropylene SBE 716 for the photoflash going to the 6922 and a 12uF for the B+ going to the 6080 also bypassed. I cannot stand the sound of Solen capacitors unless bypassed. Once bypassed they loose the grainy quality they can impart to the sound.
The batteries and capacitors are held in place with nylon ties secured to a sticky sided mounting made for this purpose. I have also noticed that there is a grid stopper on the input tube after the volume control. But for some reason it has a very long leg to the pin of the tube. These should be mounted as close as possible to the pin in order to avoid picking up any signal that they are trying to get rid of in the first place. These will be replaced with some nice 1 watt nos tantalum 220 ohm resistors that I have on hand.
Now to the sound of these changes.
After the above change and as the hours went by, the amp opened up more and more. Layering increased with the recording space being reproduced in a more and more convincing manner. I was listening to Diana Krall, “All For You”, noticing the subtle changes in her voice and her palpable presence. Saxophone on my jazz recordings has a throaty and tangible quality. I have also noted that the depth and width of the recording landscape increased, much to my listening pleasure. Bass impact has increased and the perception of “speed” in the leading edge of notes and of the plucked string gained in realism and tightness.
Noting the above changes, I wish to state that the stock Woo3 is excellent and within the constraints of its price an exceptional buy. I find that the visual presentation in fit and finish to show no compromise. That some small changes can add to the musical enjoyment, for me, only goes to show what a good design it is to begin with.
Woo3 with Amperex PQ 6DJ8 gold pin, WE 421A
The heart of the tube, the heater.
Added caps and resistor changes.
Non inductive high quality resistors in the power supply.
John