Hi,

I have a range of 12au7's from my previous amp, and have settled on the Radiotechnique NOS as the best for my Sarah.

The tubes I've tried in the Input of my Sarah:

   * NOS Radiotechnique - current
   * NOS Mullard
   * NOS Amperex Bugleboy
   * BRIMAR NOS tubes
   * Mullard NEW Gain gain tubes -150
   * RCA cleartop NOS -150
   * Tung Sol NOS -100

I think it may be possible to use 12au7 tubes in the Driver Tube positions for the 300b's with an adapter...? Curious about this....

r.

I'll second what Lon said, you can sub a 12AU7/ECC82 with an adapter for a 6922/ECC88/6DJ8.

Wow, another great tube complement. It still amazes me how more than other Decware amps I have had this SEWE300B teaches me so much about tube choices and gain structure.

I put a very old 6085 with pinched waist that I have in the ZROCK3 which gave me the characteristics I love in the SUN 12AU7s I've been using, with an added jolt of depth to the sound, and I put the Amperex red labeled 6085 as the SEWE300B driver tubes this time without the adaptors, and I put my favorite SUN 12AU7 (the oldest and most used one I have) as the input tube of the SEWE300B.

I then had to adjust the gain down in the ZROCK3 and the input gain up on the SEWE300B to avoid a hum from the ZROCK3 but wow, the sound. . . rich and dynamic and feeling real. I'm really enjoying this complement and leaving it . . . I can control volume with the DAC and get a very satisfying presentation.

I had been running it about 70 to 80 percent. . . with my most recent tube complement change I am at 85 to 90 percent. My source balanced out is about 4 volt, I have the ZBIT at about 80 percent and the ZROCK3 at about 60 percent gain out (and EQ about 90).

Also, I am not sure if I am getting the correct adapter for the 12au7 in the driver position.

https://www.amazon.com/dp/B09HNV7F2M?ref=ppx_yo2ov_dt_b_fed_asin_title

Is this right?

If not... where to find?

thanks,
r

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How efficient are your speakers?

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I'll chime in on this with the understanding that what follows is very much JMO/FWIW/YMMV. The gain of an amp, either where the volume needs to be set to achieve a given output level, or how much the volume changes for a given change in the knob depends on a lot of factors. The biggest one is just the design choices made by the creator. It doesn't really indicate anything about the amp pre se, but it does have consequences and for tube amps the choices the user makes can also be a factor.

The biggest consequence is how much input voltage aka volume you need for the amp to reach full power. For Decware it is 2 volts. A quick google for the PrimaLuna Dialogue showed me several different numbers for different models but all 1 volt or less so considerably higher. No surprise you need more volume from either your source or amp or both. Some people (not saying you) have an idea that running an amp, esp. a tube amp at full volume is somehow harder on the amp than at lower volume, but for single ended amps like 300B that is not the case. It runs the same with no music playing as it does a full power, and in fact the higher the volume the easier the amp has it because more power is sent to the speakers vs. dissipated as heat in the amp. There are also the VR tubes and using a 0A2 for the input is probably reducing the gain and output power at least a little. "Knobs" like the voicing switch and the speaker impedance may also affect the gain.

Everyone is different, and while the experience of others is interesting what really matters is what your system sounds like in your room to you. So experiment freely and keep in mind times change and people change and what sounds great today may sound less great than something else days, weeks or months from now. For me I generally run my UFO25s at about 90% volume which keeps my (non-Decware) tube preamp in its sweet spot. But with different tubes in either the amp the pre or both that can change from 60% to 100%. The only wrong answer is not trying it for yourself.

Also about 85% of my expected loudness is back. Delicious.

I have a pair of RTC dimpled slanted getter E188CC that I adore to use with my Shuguang Black Treasure 300B-Z output tubes. They have a vivid presentation that complement the warm detail of the 300B-Z perfectly. I can imagine your pair of E88CC sound great.

Currently I have a pair of Linlai 7300B-D output tubes in, as well as the Linlai 274B-D rectifier and a pair of made in Holland RCA 7308 are just right. All the tubes in a complement matter and seem to dictate choices in other positions.