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Bravo Audio - funny looking little tube amps - Page 114

post #1696 of 2601

Congratulations on your first tube amp!

beerchug.gif

Be sure to keep us posted on how you like it and the tubes you try.

BG
 

post #1697 of 2601

The Bravo Ocean arrived today! First thing first thanks alot for Jaben Australia for such a speedy delivery. Man this things is small! And boy does it have power or what! Cannot even pass the 9 o'clock on this babies. 

However I notice a humming noise at 12 o'clock, but the strange thing is when my hand is in contact with the expose section of the 1/8 inch headphone plug the noise disappears?! I think it might have something to do with some static electricity building up or something. I let it burn in for 48 hours and report back.

But for now ignoring the humming a great first impression!

post #1698 of 2601

The stock tube is bit on the bright side, I thought tubes are meant to have this 'warm' and 'lush' smooth SQ. 

 

 

UPDATE 1: The humming is due to the PSU. Replaced the PSU with an old 24 DC PSU I had and the hissing reduced to minor hissing at maximum volume. 

UPDATE 2: Bravo Ocean has an insane amount of gain. People with 600 ohm headphone will really like this greatly. Now the dilemma for me is the gain is just too much for ER-4S and akg k702. Sadly with the k702 for some reason a lot of detail from the sound track is missing :-( I dont have tha problem with the ER-4S but with the k702 the sound compared to my SS amp becomes too forward. 


Edited by audionewbi - 7/2/12 at 8:37pm
post #1699 of 2601

Darn bad RCA input :-(

post #1700 of 2601

So I have my Bravo V2 which has too much static which makes listening really uncomfortable.

 

I read that one way is by changing the PSU, but I'd like to avoid that. Resoldering was an option too which I could try. But I wanna ask if there are any part that I can upgrade to improve the sound and decrease the static before I'll sell these and get an SS amp?

 

Oh and I'm new to DIY so please explain in proper English please

post #1701 of 2601
Quote:
Originally Posted by graphidz View Post

So I have my Bravo V2 which has too much static which makes listening really uncomfortable.

 

I read that one way is by changing the PSU, but I'd like to avoid that. Resoldering was an option too which I could try. But I wanna ask if there are any part that I can upgrade to improve the sound and decrease the static before I'll sell these and get an SS amp?

 

Oh and I'm new to DIY so please explain in proper English please

Go to the Rockgrotto website, in their forum's Headphone Amplifier section, they talk about upgrades and improvements to the little tube amplifiers.

post #1702 of 2601

Update:

 

Well, it seems my V2 was nice and quiet for only just a little over a month. It started making a noise that I can only describe as what it would sound like if you would be able to plug a headphone into a noisy refrigerator. At first I thought it was the Tube I had in it, but I have two others and they sound just as bad (although slightly different, LOL).

 

Boy, I miss it though; it really made my Senn 650s sound great. I'm going to look into repairing it (I had this in the back of my mind when I first got the amp after reading so much about modding it to fix the problems these amps have so I'm kind of looking forward to that). I would advise people to not pay over $50 for this amp, because it's likely to need repairs/tweaks/mods soon.
 

post #1703 of 2601

Just picked one up for $30 including $18 in shipping. I'm excited to play with it.

post #1704 of 2601

Apologies if this question has been answered before, but I couldn't find it in searching the archives.

 

I am driving (low-impedance) Grados with an early-version Bravo (6N11 + trim pots for bias). The problem is that I can't turn the volume pot past about 8:00, and the left and right signal are out of balance. (If I turn it up to 9:00, this fixes the balance problem, but then it's too loud.) So I'm looking to replace the volume pot.

 

I make the pot to be 10K with a multimeter; the top reads 10 3B B2 2V, so I'm guessing this is 10K with "3B"-type taper, and the other two numbers I can't guess.

 

This seems to be an ALPS-style pot, although for all I know it may be a low-quality knockoff. My questions then are these:

Should I replace the pot with an ALPS pot of the same value? Would a higher- (or lower-???) value pot help the problem of not being far enough into the travel to behave in a balanced manner?

 

Thanks for any help/insight!

post #1705 of 2601
Quote:
Originally Posted by graphidz View Post

So I have my Bravo V2 which has too much static which makes listening really uncomfortable.

 

I read that one way is by changing the PSU, but I'd like to avoid that. Resoldering was an option too which I could try. But I wanna ask if there are any part that I can upgrade to improve the sound and decrease the static before I'll sell these and get an SS amp?

 

Oh and I'm new to DIY so please explain in proper English please

 

Replace the PSU, change the power filtering cap to a better Nihicon or Panasonic.

post #1706 of 2601
Quote:
Originally Posted by johnnyb3 View Post

Apologies if this question has been answered before, but I couldn't find it in searching the archives.

 

I am driving (low-impedance) Grados with an early-version Bravo (6N11 + trim pots for bias). The problem is that I can't turn the volume pot past about 8:00, and the left and right signal are out of balance. (If I turn it up to 9:00, this fixes the balance problem, but then it's too loud.) So I'm looking to replace the volume pot.

 

I make the pot to be 10K with a multimeter; the top reads 10 3B B2 2V, so I'm guessing this is 10K with "3B"-type taper, and the other two numbers I can't guess.

 

This seems to be an ALPS-style pot, although for all I know it may be a low-quality knockoff. My questions then are these:

Should I replace the pot with an ALPS pot of the same value? Would a higher- (or lower-???) value pot help the problem of not being far enough into the travel to behave in a balanced manner?

 

Thanks for any help/insight!

Unfamiliar with the old version Bravo tube amp's that take 6v tube's. But it could be:

 

Channel imbalance, have you measured bias points to have both channels equal to the same bias reading (via trim pots adjustment)? It's a possible chance that your volume pot is defective in some way, replace it with a 100k volume pot that doesn't need to be the same as Japanese ALPs pot. Another quick way to fix it is just resolder the joints of the current volume pot on the circuit.

 

All the best.

post #1707 of 2601
Quote:
Originally Posted by DefQon View Post

Unfamiliar with the old version Bravo tube amp's that take 6v tube's. But it could be:

 

Channel imbalance, have you measured bias points to have both channels equal to the same bias reading (via trim pots adjustment)? It's a possible chance that your volume pot is defective in some way, replace it with a 100k volume pot that doesn't need to be the same as Japanese ALPs pot. Another quick way to fix it is just resolder the joints of the current volume pot on the circuit.

 

All the best.

Thank you for the reply. I did check and adjust the tube bias, and the problem has persisted. So the higher-resistance pot might be a better choice? Good to know. I kind of doubt the pot is actually "faulty" in a way other then maybe low-quality, just because at higher volumes the balance is perfect to my ear. By reputation at least ALPS is a pretty decent product, so I will go with that brand unless I hear a strong opinion otherwise.

 

Thanks again!

post #1708 of 2601
Quote:
Originally Posted by johnnyb3 View Post

Apologies if this question has been answered before, but I couldn't find it in searching the archives.

 

I am driving (low-impedance) Grados with an early-version Bravo (6N11 + trim pots for bias). The problem is that I can't turn the volume pot past about 8:00, and the left and right signal are out of balance. (If I turn it up to 9:00, this fixes the balance problem, but then it's too loud.) So I'm looking to replace the volume pot.

 

I make the pot to be 10K with a multimeter; the top reads 10 3B B2 2V, so I'm guessing this is 10K with "3B"-type taper, and the other two numbers I can't guess.

 

This seems to be an ALPS-style pot, although for all I know it may be a low-quality knockoff. My questions then are these:

Should I replace the pot with an ALPS pot of the same value? Would a higher- (or lower-???) value pot help the problem of not being far enough into the travel to behave in a balanced manner?

 

Thanks for any help/insight!

Have you fine adjusted and balanced the right and left voltage channels?

post #1709 of 2601
Quote:
Originally Posted by johnnyb3 View Post

Apologies if this question has been answered before, but I couldn't find it in searching the archives.

 

I am driving (low-impedance) Grados with an early-version Bravo (6N11 + trim pots for bias). The problem is that I can't turn the volume pot past about 8:00, and the left and right signal are out of balance. (If I turn it up to 9:00, this fixes the balance problem, but then it's too loud.) So I'm looking to replace the volume pot.

 

I make the pot to be 10K with a multimeter; the top reads 10 3B B2 2V, so I'm guessing this is 10K with "3B"-type taper, and the other two numbers I can't guess.

 

This seems to be an ALPS-style pot, although for all I know it may be a low-quality knockoff. My questions then are these:

Should I replace the pot with an ALPS pot of the same value? Would a higher- (or lower-???) value pot help the problem of not being far enough into the travel to behave in a balanced manner?

 

Thanks for any help/insight!


your experience with this amp is typical & the replies are also typical (& less anyone misunderstand, i am not criticizing anyone here since i have gone thru the same issue with bravo & indeed v1 & v2) and are all correct to an extent.  the big issue is that you are attempting to use a low impedance headphone with a medium mu (gain) amp.  the left & right channels don't track well at the extremes because these pots are low-quality & attempting to replace the pot with a higher quality one risks damaging the circuit traces (they look good but they are far from durable).  i really wouldn't bother with attempting to mod these unless you have some experience in diy (if you do, then look in the rock grotto forum for the modding thread which will help you to transform the sonic quality of these amps ... but it still won't resolve the gain issue and tracking).  the cheapest route out of this is to use impedance adapters for your headphones and look for a better (sonic) quality 6dj8 tube.  once you have come to the realization that putting any more $ into this is just throwing good money after bad, go to garage1217's site & pick up his sunrise amp which really does justice to a single tube (6dj8/12au7 etc) hybrid amp design.  ofc, a cheaper solid state route is to go for something like the fiio.  or for more $, try the o2.

post #1710 of 2601

Thanks, geetarman, for a thoughtful response. I sorta had upgraditis anyway, so I guess I'll pass that one along to a friend with higher-impedance cans. 

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