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Bravo Audio - funny looking little tube amps - Page 107

post #1591 of 2599

Unrelated question... a week after using this amp (the Bravo V2 12AU7) with the stock chinese tube, it won't work anymore. The red light for power is on, and the blue light under the tube is on. But there is no tube glow whatsoever (while normally you see two filaments glow when it's working). If headphones are plugged in, I hear a crackle when it turns on and off... but no sound whatsoever otherwise. Could it be my tube is a dud? 

post #1592 of 2599

Try a tube first... Would be my first guess with what you are describing.

post #1593 of 2599

Had to edit, not a sponsor.


Edited by Garage1217 - 6/8/11 at 12:52am
post #1594 of 2599

PM sent biggrin.gif

post #1595 of 2599

Garage, can't wait to see the first photos of your modified Bravo! Can't wait to own one too, if they're as good as you're saying. :)

post #1596 of 2599

I read through most of the thread, but I might have missed it.

 

There's plenty of warning about lifting traces, but not enough advices for people with little experience:  How do you avoid lifting traces ? Lower the iron heat ? 

post #1597 of 2599

Use a solder sucker for one and make sure each pin is loose before removing the component. I know it sounds easy when I say it as I have years of soldering experience overall.... but mods can be tedious for a person that is a newcomer to the ways of the iron lol One thing that helps if you are new to soldering, find some old POS electronic device with through hole components and start removing them / re-soldering them over and over :)

post #1598 of 2599

The Brave's PCB is so fragile, even for experienced soldering people. You probably can cirumvent this by using the cut leads from resistors or caps, bypass the lifted or broken trace.

 

I was so impatient to replace the caps, so I kind of lifted the copper and destroyed it. So I just make use of a wire foot from a resistor to bypass it to the FET. I put a piece of shink wrap on it to avoid short circuiting.

 

IMG_0996.jpg

post #1599 of 2599

Hi everyone,

 

I'm a newbie here, so having newbies' questions ; maybe already been discussed thru the 107 pages ...?

So, got this MHHA, mine is a copy of this just acceptable amp (like Bravo/Indeed/Muse ...).

 

Sure everyone here started the same tweaks, changing those VERY BAD parts :

1. chinese 6N11 tube >> RCA made ECC88, waiting for a NOS Sylvania made 6DJ8

2. under rated / low cost power caps >> Panasonic/Elna 35/50V ones + bypass caps (if not)

3. standard IRF630 MosFETs >> more 'musical' IRL510 ones (or IRL530 or 2SK310 ...)

4. standard Elna RJJ output caps >> 'dedicated for audio' ones

    (mine are NOS Elna like ROA/RW5 miniaturized, 105°C, bypassed w/ ERO/Vishay MKP1837 22nF)

5. output Dale metal layer resistors >> Welwyn wirewound 47R

6. input ground resistor 8,2K >> 91K 1/2W

+ also have to change the input resistor (!!!) to a Cap (obviously) : NOS Sprague 150nF 100V will fit

+ the mediocre potentiometer (to small ALPS RK09)

 

So ... my question is : since I changed the MosFET, the IRL and the LM317 became hot, I mean VERY HOOOT !

Is it something I could fix or did I make something wrong ? I changed to massive heatsinks, still hot (maybe > 40°C).

 

I checked and ajusted the bias, but : I can read 13,5V here, or 15V there, dunno what value's the best ...

(but my sh## was initially set to ~10V @ R and 6V @ L !... did I say BAD ?)

My power supply is 19V, not 24V (I'm in France, EU, and the stuff came from China with a plug only for UK I guess) ; I have a 24V tomorrow.

 

Whatever if I can fix that or not, these little mods really worth to switch on the iron !! Now closer to an audiophile product.

 

post #1600 of 2599

You might have better luck cut-and-pasting your question into this site:

 

 

http://rockgrotto.proboards.com/index.cgi?board=b

 

You could drown in the DIY detail lavished on the Bravo/Indeed/Muse amplifiers.

post #1601 of 2599

Hello...

- 40C is not hot at all for an lm317 or irl510. Heck we get well over 40C ambient here in the desert of Az hahaha! The 317 is rated to 170C and the 510 to 120C which is HOT. In general a bravo v2 will run around 55C on stock sinks or up to 60-65C with the acrylic top on. For your mods, in general around 13.5 is a good choice and what I tune my builds to. Get that 24V power supply in and stick with it :)
 

Quote:
Originally Posted by nanaud View Post

Hi everyone,

 

I'm a newbie here, so having newbies' questions ; maybe already been discussed thru the 107 pages ...?

So, got this MHHA, mine is a copy of this just acceptable amp (like Bravo/Indeed/Muse ...).

 

Sure everyone here started the same tweaks, changing those VERY BAD parts :

1. chinese 6N11 tube >> RCA made ECC88, waiting for a NOS Sylvania made 6DJ8

2. under rated / low cost power caps >> Panasonic/Elna 35/50V ones + bypass caps (if not)

3. standard IRF630 MosFETs >> more 'musical' IRL510 ones (or IRL530 or 2SK310 ...)

4. standard Elna RJJ output caps >> 'dedicated for audio' ones

    (mine are NOS Elna like ROA/RW5 miniaturized, 105°C, bypassed w/ ERO/Vishay MKP1837 22nF)

5. output Dale metal layer resistors >> Welwyn wirewound 47R

6. input ground resistor 8,2K >> 91K 1/2W

+ also have to change the input resistor (!!!) to a Cap (obviously) : NOS Sprague 150nF 100V will fit

+ the mediocre potentiometer (to small ALPS RK09)

 

So ... my question is : since I changed the MosFET, the IRL and the LM317 became hot, I mean VERY HOOOT !

Is it something I could fix or did I make something wrong ? I changed to massive heatsinks, still hot (maybe > 40°C).

 

I checked and ajusted the bias, but : I can read 13,5V here, or 15V there, dunno what value's the best ...

(but my sh## was initially set to ~10V @ R and 6V @ L !... did I say BAD ?)

My power supply is 19V, not 24V (I'm in France, EU, and the stuff came from China with a plug only for UK I guess) ; I have a 24V tomorrow.

 

Whatever if I can fix that or not, these little mods really worth to switch on the iron !! Now closer to an audiophile product.

 



 

post #1602 of 2599

I am planning on purchasing one of these amps soon to pair with a closed pair of DT880/600 (personal preference mod). I am confused as to which model I should get though because his store lists 5 products, of which one is a pair of tubes and another product is meant to be used as a guitar amp. What are the differences between the other three remaining amps? I know the V3 has equalizers but I am unsure if I would use that feature. But the V2 and the other amp look identical but use different tubes I think. Really looking for differences in sound quality. Any help would be appreciated.

post #1603 of 2599

New to this amp, im using 12AU7, which would be a good option(s) to roll the tube?

post #1604 of 2599
Quote:
Originally Posted by suhaybh View Post

I am planning on purchasing one of these amps soon to pair with a closed pair of DT880/600 (personal preference mod). I am confused as to which model I should get though because his store lists 5 products, of which one is a pair of tubes and another product is meant to be used as a guitar amp. What are the differences between the other three remaining amps? I know the V3 has equalizers but I am unsure if I would use that feature. But the V2 and the other amp look identical but use different tubes I think. Really looking for differences in sound quality. Any help would be appreciated.



The Indeed MK2 12AU7 is the best option at the moment. It's easier to mod and has a better build quality compared to the Bravo's. Check Rockgrotto forums for everything you ever wanted to know about these amps. Mind though, that these amps are pretty underwhelming at first. They're hissy, hot and don't sound particularly good. Modding them is the way to go if you want to do your DT880 right. :) For example, my Bravo V2 12AU7 has exploded twice on me already. I'm still procrastinating fixing it again. bigsmile_face.gif


Edited by Negakinu - 6/7/11 at 12:06am
post #1605 of 2599

I am really looking for an amp that I wouldn't need to mod because I don't have a lot of spare time and I have never used a soldering iron before. If I am going to buy an amp my two requirements would be as little background noise as possible when listening with headphones and that the amp operates so that it doesn't get too hot. I would prefer the amps be on the smaller side and of course less than $100. Am I asking for to much or are there any amps that can lend themselves to these requests?

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