Bravo Audio - funny looking little tube amps
Aug 21, 2012 at 5:39 PM Post #1,711 of 2,720
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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. 


you're welcome & wise move on that ...
if your budget is tight, perhaps one of the fiio models will do the trick for you.  otherwise, i stand by my recommendation for project sunrise if you're looking for a tube hybrid or the O2 if you want to stick with solid-state.
 
Sep 5, 2012 at 7:39 PM Post #1,712 of 2,720
Bought today a RCA Cable instead the 3.5 to 3.5mm i was using and when i was playing i noticed that the sound was all messed up, like the sounds that suposed to come from the left i was listening them on the right side of the headphones. I removed the audio enhancers programs i was using thinking it was from there, well it wasnt. Restarted the pc, no luck. Then I thought it could be the cable so i swapped them, white on red input and red to white input. And it worked!
 
So now im thinking is it the cable or the bravo that have the rca inputs swapped?
 
And is there a problem if i use them swapped even if thats the only way they work correctly?
 
 
The cable was quite cheap. Evology is the brand.
 
Sep 6, 2012 at 10:00 AM Post #1,713 of 2,720
Oh, awesome! I've wanted a cheap tube amp for a while. I've been investigating this one by fred_fred: http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=200807704603#ht_4069wt_1041
^Anyone know how that might compare to the Bravo V1/V2? 
 
Sep 12, 2012 at 5:14 AM Post #1,716 of 2,720
Replaced IRF630's to IRL520PBF's (the best mosfets I could find in Estonia) on mine amp and now I couldn't be happier :) Even that small tuning changes sound. No more cut off treble and muddy bass. Now V2 sounds concrete like SS amp, but with warmth and liquidity of tube amp. But I noticed that both right channel mosfets are much hotter. I can hold my finger on them maximum one second, but on leht channel mosfets I can hold my finger for about three/four seconds. Could anybody know, what's the problem?
 
Sep 13, 2012 at 1:45 PM Post #1,717 of 2,720
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Replaced IRF630's to IRL520PBF's (the best mosfets I could find in Estonia) on mine amp and now I couldn't be happier :) Even that small tuning changes sound. No more cut off treble and muddy bass. Now V2 sounds concrete like SS amp, but with warmth and liquidity of tube amp. But I noticed that both right channel mosfets are much hotter. I can hold my finger on them maximum one second, but on leht channel mosfets I can hold my finger for about three/four seconds. Could anybody know, what's the problem?


offhand, i would say that more current is flowing thru right channel.  the right channel should sound louder than the left (is this the case?). 
 
have you adjusted the trimpot to match bias voltage on both sides?  if you have and this behavior is still continuing, then i would suggest checking the tube for section mismatch & replace it with one that has balanced sections.
 
Nov 11, 2012 at 4:34 PM Post #1,719 of 2,720
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Do I really need to unplug the hp's before turning OFF the amp, as well as, first turn ON the amp then plug the hp's?

Yea, better to plug or unplug before touching the power switch.
Some of the newer designed single tube amp. come with a built in power up delay, to protect the headphones.
 
Nov 11, 2012 at 4:48 PM Post #1,720 of 2,720
Hmm, i see. It annoys me, always doing that.
 
So Im thinking of buying a fiio e10, not only because i dont need to have this care, of unplug and plug, but because i heard it have a good synergy with the DT 990 PRO's. But Im not sure if its better than the bravo with a vintage mullard tube that i bought.
 
What do you think?
 
 
Nov 11, 2012 at 5:00 PM Post #1,721 of 2,720
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Hmm, i see. It annoys me, always doing that.
 
So Im thinking of buying a fiio e10, not only because i dont need to have this care, of unplug and plug, but because i heard it have a good synergy with the DT 990 PRO's. But Im not sure if its better than the bravo with a vintage mullard tube that i bought.
 
What do you think?
 

The tube might(?) make the DT990s sound better.
 
Nov 11, 2012 at 6:14 PM Post #1,722 of 2,720
Quote:
Replaced IRF630's to IRL520PBF's (the best mosfets I could find in Estonia) on mine amp and now I couldn't be happier :) Even that small tuning changes sound. No more cut off treble and muddy bass. Now V2 sounds concrete like SS amp, but with warmth and liquidity of tube amp. But I noticed that both right channel mosfets are much hotter. I can hold my finger on them maximum one second, but on leht channel mosfets I can hold my finger for about three/four seconds. Could anybody know, what's the problem?

The IRL520's will do the job, being better then the F counterparts, but you had settled for a Fairchild IRL510 then man, would you be in for a surprise. It is normal the mosfet's are more hotter now, this is normal. If you want to reduce the heat a bit, replace the the large 25v 6800uf power capacitor to a 25v 10000of or 35v 6800uf capacitor, don't worry the supply of more volts will not kill the amp, but right now that 25v 6800uf cap is limiting the power input into the amp from the 24v wallwart being used, a bump in v for the cap or uf will give it some more headroom providing a more clearer sound.
 
Remove the two resistors next to the tube near the LM317 mosfets (silver heatsink) to trimpots, bias adjust the voltage of the tube to the required amount, there are reference charts for the 12v triode tubes you can adjust the bias to, this will provide a more balance to the sound and certainly can reduce any slight voltage swings and extra heat on those IRL520's.
 
For tube rolling, I definitely recommend you trying Sylvania O getter (black or grey plates), they mix in with the sound of the those IRL520's very good. 
 

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