Advice for Bada PH 12 owners:
Must not take out tubes until the amp has been turned off for some time - removing tubes when some residual power is in the amp can weaken the mosfets. I turn off and wait 12 hours or more before removing tubes to change them. I do much tube changing and have blown about 3 mosfets over a year's time by not leaving the amp off long enough before removing tubes. To absolutely insure no damage to mosfets: Only take out tubes (in changing them) when the amp has been off overnight - do tube changes only once a day at the most, and do so only just before you go to turn it on for the first time that day. The tube has to remain in the circuit until power stored in the circuit dissipates. People who do this never have any trouble.
Insert and remove tubes by holding the base and not the glass part - twisting or pulling on the glass can loosen it from its base. Also, take care in correctly lining up the tube pins when putting in a tube - it is possible to force the tube in when the pins are misaligned (won't get audio out of one or both sides that way). I use a black felt marker and mark the top of the Bada to line up with the guide pin slot, then put tape on the tube base, adjacent to the pin guide, lining up the two when inserting a tube.
The Bada can be used with dozens of 6SN7 tube combos that all sound good - as well as many that don't sound good at all. The dozens that are good are each different from each other - like having dozens of great amps to choose from. Using different tubes, I can configure my Bada to sound like other amps, or to sound best with particular CDs, etc.
Update 4/07: My "Gold Standard" combos are:
Sylvania WGT with two Chinese Shuguang in back
Electro Harmonix Gold with two Chinese in back
RCA GT Black glass (clear glass GT may be as good) with two Raytheon GT T-plates
RCA GT Black glass (clear glass GT may be as good) with two Sylvania W
Electro Harmonix Gold with two Raytheon GT T-plates
Chinese Shuguang GT in front and two Sylvania GTA or WGTA
Ken Rad GT (staggered plates not parallel plates) with two Chinese Shuguang in back
My favorite combo with the Shugang: Two Shugang 6H8P (6SN7) with one Sylvania WGT (or Electro Harmonix Gold) is a real winning combo in the Bada 12. Detail, sharp 3-D imaging, strong bass, transparency, and nice natural timbre.
Individual preferences dictate which combo is best and some of the other combos below may be best to some.
The Electro Harmonix 6SN7 GT Gold (only the Gold) is most similar to the Sylvania W GT in sound. Either one makes a good input tube when used with two Raytheon VT 231 (or GT) as outputs - one of my favorite tube combos. Now, the Raytheon come with either T black plates or flat black plates, and sound different. The Raytheon GT with flat plates is smooth with lovely timbre, and has softer edges and a more forgiving sound than the T plates. However, the T plates is a sharper and highly resolving sound that shines if used with the best sources and headphones - those who like the Raptor would really love this sound (not as lean as the Raptor with a fuller tone body). However, if you use a Sylvania W used instead of the Sylvania W GT as input, with the Raytheon GTs still as outputs, there is a shift more to the rich-tone-body/soft-tone-edge of the spectrum (away from the lean tone/sharp edge side), which lends a soft liquidity with reduced tone image (instrument) separation. Some may like this but many will find it is too euphonic, as I do.
When I want a high resolution sound that separates instruments and reveals inner detail in complex orchestration, and has strong bass, I use the EH Gold with two Raytheon VT231 (or plain GT) with black T plates. When I want a softer and smoother sound with some more tone richness then I use other combos.
Tbonner1 alerted me to using the Chinese Shuguang GT (variously designated as a 6N8C or a 6SN7) in front and two Ken Rad GT or VT231 (staggered plates only). This combo is a real winner - one of the very best for sure. Detailed, high resolution, with strong bass (too much bass with the HD650 though) and natural (but lean, like solid state) timbre - to overcome the leanness use two Sylvania WGT with the Chinese Shuguang GT - one of my favorites. I have been getting good results from the lowly GTB tubes. I used two Sylvania GTB as outputs - these are silmilar to Ken Rad in being mellow and slightly rich in tone - and I used a Japanese GTB (hard to find - two are Hit Ray and the other two are Signet - both brands look the same and likely made by Matsu****a) as the input tube. I was very pleased - open, detailed, sharp images, like the Shuguang and Ken Wood combo but without the touch of harshness, and not as lean - however the bass was not quite as strong. I used an Ensign GTB (God knows who makes it - think it is European) as the input with the two Sylvania GTBs and this is also quite good - slightly richer than above. GTBs can be good (from Sylvania, Tung Sol, Raytheon, and Japanese and European brands) and are inexpensive.
Another really great combo uses a Sylvania GT or VT231 with T plates and two Raytheon 5692 brown base.
Now, if you use the Sylvania W as input with two GE GTA or two Ken Rad VT -231 (or GTs) as outputs, you get a nice balance between rich tone/soft edge and lean tone/sharp edge. However, the Sylvania W and two Ken Rads have richer and fuller (and more liquid) tones with stronger bass but softer tone edges (lower resolution that is good for poorly recorded CDS), while the W and two GE GTAs are higher resolution with sharper tone images and better 3-D imaging, will being slightly less rich, liquid and full. I much prefer the latter with good recordings but prefer the former with many older recordings. However, if you use the Sylvania W GT here instead of the W (as the single input) - with the two GE GTAs or two Ken Rad GTs - you shift decidedly back to a rich tone/soft edge and it is too euphonic. However, a great compromise between the two above combos is to use one Sylvania W with two Sylvania JAN CHS GT with triangle black plates (or two Sylvania VT231 GT with T black plates for slightly more detail) - could be the best for you.
Now, take two Sylvania W as the output tubes, with one Raytheon VT231 (or GT) as the input tube and you have detail but it is too lean. So use a RCA VT 231 (or GT) as input and the same two Sylvania W tubes as outputs and you get one of the very best overall with most CDs - combines detail, sharply defined tone images focused in empty space, transparency, and a naturally rich timbre. Sub a Tung Sol GT "mouse ears" for the RCA VT 231 here, keeping the two Sylvania W, and you get another excellent combo.
Another neutral balance combo is to use the Sylvania W GT with two Tung Sol GT White Label gray plates (not the mouse ears) instead of the Raytheons. To shift really further to a lean tone body/sharp tone edge, use the Sylvania 6SN7W GT as input with the harsh and hard sounding Shuguang 6N8P (sometimes labeled 6SN7 GT and Made in China) as output tubes. A lean but very sharp imaging and detailed sound. However, this combo can still be edgy and harsh at times, because of the Chinese tubes used.
It is the combo that is perhaps more important than the tubes used, and it best to use different tube types as input and output tubes rather than the same type in all positions (but use the same in all input positions and then the same in all output positions but different between the inputs and outputs - very simple: different but the same). The Tung Sol Round Plate GT and Sylvania W are perhaps the two best 6SN7 tubes ever (the RCA VT231 and GT black glass rank here also), but I can configure them with certain tubes to get a very bad sound. Also, if I use Sylvania Ws (or any other tube) in all positions of input and output, the sound suffers over other combos.
Other good combos using old tubes from the 40s and 50s, not in order of best sound, any one of these could be the absolute best for you, and the bad combos are not discusssed:
1. Ken Rad VT-231 (or plain GT) as input and two RCA VT-231 (or plain GT) as outputs. Raytheon VT-231 or GT works well here instead of the Ken Rad. One Tung Sol GT Black Glass round plates with two RCA CRC GT (or RCA VT-231 or RCA GT) is a variant here that would be the very best for many.
2a. Raytheon WGT or Sylvania VT-231 (or plain GT, or GE USA GT) as input and 2 RCA VT-231 (or plain GT) as the output tubes - a great all around combo that I like very much and that some would regard as the best. 2b. If you use the Sylvania GTA (instead of the GT) as the input tube, keeping with the RCA GTs as outputs, you add slightly more tone edge sharpness and slightly less tone body, and some may like this. Using one Sylvania GT as input with two RCA GT as outputs provides the best bang for the bucks, and is close to the more expensive combos. The Sylvania VT231, CHS and GT comes with either black triangle plates (softer, smoother) or black T plates (more detail and resolution) - select on this basis.
3a. Sub the Tung Sol GT white label gray plate for the Sylvania above (as input) and keeping 2 RCA VT-231 (or plain GT) as the output tubes, adds more transient bite and sharper imaging with slightly less liquidity and tone body richness, for a very realistic sound.
3b. Also, I have a Tung Sol GT black plate (with a small dual rectangular plate extension that protrudes above the top mica - very unusual) that is too euphonic with the two RCA GTs, 3c. but is better (some slight sibilance at rare times) with two RCA GTAs.
3d. Now, take this same unusual Tung sol GT black plate and use it with two Sylvania VT-231 and you get enough improvement to make this one of the best combos. It is the combo that is as important as the tubes used. 3e. I have a tall bottle black plate Tung Sol GTB that also sounds good with the Sylvania VT-231s - the GTB sounds like the Tung Sol GT and may in fact be a GT mislabeled as a GTB (happened some with Tung Sol tubes).
4. Ken Rad VT-231 (or plain GT) as input and GE GTA as the output tubes - detailed treble, great midrange clarity and 3-D tone imaging with a nice natural timbre and tone body, makes this combo the best for some people.
5. Electro Harmonix Gold GT as input with two GE GTA as outputs. Adds some tone body richness/fullness compared to the above combo - a little more life, excitement, etc. An inexpensive tube set up that sounds quite good.
6. Tung Sol GT "mouse ears" black plate as input and two GE GTA as outputs. A little better treble timbral nuance and contrast than the above makes this a contender for the very best. Has a real nice timbre with a pristine quality. Also try two Tung Sol GT mouse ears with one RCA VT 231 or GT black plate - ranks with the best.
7. Tung Sol GT "mouse ears" black plate as input and two Sylvania VT-231 or GTs as outputs. A little more refined sound than #6 above but at the expense of slightly less timbral contrast. Some will prefer this. Tung Sols go well with the Sylvania Vt-231/GT with the exception of the mouse ears - don't have a round plate yet.
8. CBS GT or GE Canada GT as the single input tube, and 2 RCA GT VT-231 (or plain GT) as the output tubes. Solid realistic sound - leaner tone than number 2 above.
9. RCA VT-231 (or GT) as the input tube and 2 Raytheon VT-231 (or GT) as the output tubes. Another solid combo.
10. Raytheon GT VT-231 (or plain GT) as the input tube and two Sylvania or RCA VT-231 (or GT) as the output tubes.
11. Sylvania W GT (not W and not GT and not VT-231) as input and two Sylvania GTA (not GT, VT-231 or GTB)
