ShaolinGrump
100+ Head-Fier
I just got a Bravo Ocean amp from The Earth City Sound Company, a reputable seller on eBay. I think I have a failing left channel, or some problem with tube rolling that I don’t understand.
My testing gear and sources are listed at the bottom.
The Bravo arrived on my lunch hour. I had everything ready to go to start listening tests. I had extra tubes on hand, so I put in a Russian reissue Mullard. I did this right away, before testing the unit. I’ve learned to carefully rock tubes in and out, and to make sure they are well seated. My tube rolling experience is short but good until now.
The Bravo Ocean only plays stereo correctly with the stock Shugang tube. I’ve tried the Mullard, PSVANE and Genalex listed below. They all struggle or fail to play the left channel. The PSVANE warms up into the left channel, it sounds nice for a moment, and then the left cuts out and/or plays garbled, minimal signal. The Mullard never plays the left channel. I didn’t test the Genalex too thoroughly because it’s my favorite in the other amp, but it didn’t play well through the left channel in the Bravo Ocean.
I isolated the problem by extensive listening and fiddling using my Sennheiser HD 280 pro headphones. I could get both ears to work, if I partially inserted the plug into the 1/4” jack using Sennheiser’s screw-on 3.5 to 1.4” adapter. The 3.5 plug in the 3.5 jack only played both ears if I barely inserted the plug and left it hanging crooked in the jack. I think I was hearing right channel or mono in both ears using these methods. It didn’t sound like good stereo. My other repeated tests were: (1) warming up the tubes by increasing the volume beyond safe listening, with phones off my head of course, and then checking to see if both ears were playing, and (2) listening for a while at comfortable volume and pulling each ear away from my head to see if I had balanced volume from each side.
I used the RCA interconnects to confirm as best I could that it was the left channel. If I only used the right RCA input jack, it sounded clean. If I only used the left RCA jack, it sounded muffled, garbled or almost silent with little pops or static.
The stock Shugang plays stereo well in all my tests. I like its performance, but I don’t love it. The overall sound is good in the Sennheiser HD 280 pro, but I don’t love those headphones in any application; they are my reference cans but not for the pleasure of listening. The Bravo Ocean with stock tube drives my Sendy Aiva well. I think the Bravo to the Sendy gets the best performance from any of my gear combos. But the Sendy are more fatiguing on the Bravo than my other rigs. I think this is a top end tonal range issue, so I was hoping to roll tubes and find a more relaxed top end out of a different tube.
The PSVANE tube sometimes plays nicely in the Bravo Ocean. But the more I listen, the more I can notice that the left channel is fainter than the right. The volume is less and/or it just isn’t playing everything that the source is trying to deliver, like one voice in a duet or stereo fade tricks in electronica. Other times, when I roll the PSVANE back in after testing other tubes, I get muffled and garbled left channel. Fiddling gently to seat the tube sometimes helps open the left channel, sometimes not.
Bottom line: What is up with my Bravo Ocean left channel? Three tubes test nicely in stereo in my xDuoo, and fail partially or miserably in the Bravo.
Tubes:
Shugang 12AU7 (stock from Bravo Ocean)
PSVANE ECC82 (stock from xDuoo TA-10R)
Genalex Gold Lion 12AU7/ECC82 gold pin (tested by Upscale Audio)
Mullard 12AU7/ECC82 Russian re-issue (tested by Upscale Audio)
Testing and Comparison gear:
xDuoo TA-10R DAC/amp (comparison amp to confirm tubes and headphone connections)
Oriolus BA300S pocket amp (comparison for subjective listening experience)
Lotoo PAW S1 pocket DAC/amp (comparison for subjective listening experience)
Sendy Aiva planar magnetics, 32ohm (with stock 3.5 adapter)
Sennheiser HD 280 pro, 64ohm (with stock 1/4” adapter and 3.5 plug)
Master & Dynamic MW60, 32ohm (wired mode, with stock 1/4” adapter and 3.5 plug)
Sources:
Apple Lossless digital files
Arcam rDock (for 30pin iPhones and iPods) via Morrow Audio RCA interconnects and crusty old Radio Shack RCA
Apple A1352 30-pin dock via newish Belkin 3.5mm patch cable
Various iPods and iPads via newish Belkin 3.5mm patch cable
My testing gear and sources are listed at the bottom.
The Bravo arrived on my lunch hour. I had everything ready to go to start listening tests. I had extra tubes on hand, so I put in a Russian reissue Mullard. I did this right away, before testing the unit. I’ve learned to carefully rock tubes in and out, and to make sure they are well seated. My tube rolling experience is short but good until now.
The Bravo Ocean only plays stereo correctly with the stock Shugang tube. I’ve tried the Mullard, PSVANE and Genalex listed below. They all struggle or fail to play the left channel. The PSVANE warms up into the left channel, it sounds nice for a moment, and then the left cuts out and/or plays garbled, minimal signal. The Mullard never plays the left channel. I didn’t test the Genalex too thoroughly because it’s my favorite in the other amp, but it didn’t play well through the left channel in the Bravo Ocean.
I isolated the problem by extensive listening and fiddling using my Sennheiser HD 280 pro headphones. I could get both ears to work, if I partially inserted the plug into the 1/4” jack using Sennheiser’s screw-on 3.5 to 1.4” adapter. The 3.5 plug in the 3.5 jack only played both ears if I barely inserted the plug and left it hanging crooked in the jack. I think I was hearing right channel or mono in both ears using these methods. It didn’t sound like good stereo. My other repeated tests were: (1) warming up the tubes by increasing the volume beyond safe listening, with phones off my head of course, and then checking to see if both ears were playing, and (2) listening for a while at comfortable volume and pulling each ear away from my head to see if I had balanced volume from each side.
I used the RCA interconnects to confirm as best I could that it was the left channel. If I only used the right RCA input jack, it sounded clean. If I only used the left RCA jack, it sounded muffled, garbled or almost silent with little pops or static.
The stock Shugang plays stereo well in all my tests. I like its performance, but I don’t love it. The overall sound is good in the Sennheiser HD 280 pro, but I don’t love those headphones in any application; they are my reference cans but not for the pleasure of listening. The Bravo Ocean with stock tube drives my Sendy Aiva well. I think the Bravo to the Sendy gets the best performance from any of my gear combos. But the Sendy are more fatiguing on the Bravo than my other rigs. I think this is a top end tonal range issue, so I was hoping to roll tubes and find a more relaxed top end out of a different tube.
The PSVANE tube sometimes plays nicely in the Bravo Ocean. But the more I listen, the more I can notice that the left channel is fainter than the right. The volume is less and/or it just isn’t playing everything that the source is trying to deliver, like one voice in a duet or stereo fade tricks in electronica. Other times, when I roll the PSVANE back in after testing other tubes, I get muffled and garbled left channel. Fiddling gently to seat the tube sometimes helps open the left channel, sometimes not.
Bottom line: What is up with my Bravo Ocean left channel? Three tubes test nicely in stereo in my xDuoo, and fail partially or miserably in the Bravo.
Tubes:
Shugang 12AU7 (stock from Bravo Ocean)
PSVANE ECC82 (stock from xDuoo TA-10R)
Genalex Gold Lion 12AU7/ECC82 gold pin (tested by Upscale Audio)
Mullard 12AU7/ECC82 Russian re-issue (tested by Upscale Audio)
Testing and Comparison gear:
xDuoo TA-10R DAC/amp (comparison amp to confirm tubes and headphone connections)
Oriolus BA300S pocket amp (comparison for subjective listening experience)
Lotoo PAW S1 pocket DAC/amp (comparison for subjective listening experience)
Sendy Aiva planar magnetics, 32ohm (with stock 3.5 adapter)
Sennheiser HD 280 pro, 64ohm (with stock 1/4” adapter and 3.5 plug)
Master & Dynamic MW60, 32ohm (wired mode, with stock 1/4” adapter and 3.5 plug)
Sources:
Apple Lossless digital files
Arcam rDock (for 30pin iPhones and iPods) via Morrow Audio RCA interconnects and crusty old Radio Shack RCA
Apple A1352 30-pin dock via newish Belkin 3.5mm patch cable
Various iPods and iPads via newish Belkin 3.5mm patch cable
