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Bravo Audio - funny looking little tube amps - Page 108

post #1606 of 2703

Yes, you are asking too much. No amps under 100$ match your needs. Otherwise there people won't be busy tinkering this little wonder wink_face.gif.

post #1607 of 2703

All of the Bravo/Indeed/Muse amplifiers get hot, but the heatsinks and open design radiate the heat effectively for the most part.  So "too hot" is one of those "Goldilocks" phrases; what does it really mean in context?  They are all small.  Under $100 with no DIY mods, the Indeed G2 seems to be the consensus pick among the variants of this basic design, but something new has emerged from the huge DIY modification culture: a new amplifier (available as parts, a full kit or assembled) which incorporates most of the proven mods for the Bravo/Indeed into the design from the start.  Here is the Rock Grotto thread on the Project Sunrise amp:






Edited by attenuated 3db - 6/9/11 at 4:12pm
post #1608 of 2703

Hey Jeremy, great job.

Edited by Jazzyfi - 6/7/11 at 11:20am
post #1609 of 2703

Thanks folks for advices !


Trully, mine became "hot" when I changed the Mosfet, maybe it changed from ambient temp. +5°C to +25°C approx. ; even if I changed heatsinks from ~16°C/W to ~8°C/W...

But I see here I should "relativize" what's warm and what's hot ;-)


I dunno for all of you, but in the same time, I'm starting this same kind of project from scratch : 



on a brand new and clear PCB (70% larger) found on :



Maybe a time for "benchmark" will come soon after.

post #1610 of 2703

I just got my Indeed Mk.2 (meant to order a "G2" but was not alert when I clicked the eBay "Buy Now" button) today, and am generally impressed.  It has been awhile since I had to let my Maverick A1 with its factory-matched pair of Raytheon 6AK5s go, effectively going without a head amp for a couple of months, so I can't do any direct comparison, but the Indeed seems to lack the dynamics (especially at the ends of the frequency spectrum) of the Maverick, but that's the difference between a $60 and $240 amp, especially in terms of power supply-imposed limitations.  One thing that I am struck with is that the Indeed Mk.2 runs a lot cooler than I anticipated.  I don't want to leave my finger on a MOSFET heatsink any longer than I have to, but the plexiglass top is cool to the touch.  I was preparing for a potential fire hazard given some of the heat stories I've read, but not so.  Nice product, well-packed that arrived very quickly (11 days from China to US).  I'd still advise others to get a Indeed G2 if they're in the market for an Indeed amp.

post #1611 of 2703

I'm very curious to what the 680uf bias caps actually do.

I have a V2 bravo and just bypassed the 1uf Rubycons with 2.2uf Wima ones to hear what different it would make, it changed the bass some what.



post #1612 of 2703

Hello again,


I just bought many of the parts for the mods to this amp from mouser and now have a few more questions (sorry, kind of a noob here).

First, how do I measure the bias on the trim pots so that I can adjust it accordingly?

Second, how do I cut the traces for the crosstalk improvement mod? Do I just use an X-acto knife, and then solder onto the already existing joint? Also, will any wire work for it?




Edited by duheee - 6/12/11 at 2:13pm
post #1613 of 2703

There are quite a few variants of the Bravo/Indeed/Muse amps. If you just want direction on adjusting bias, this link on rock grotto is a good guide. There is much more DIY info on that website, including links to downloadable PDF files that take you through all of the mods with pictures and diagrams.

post #1614 of 2703

I can't seem to find the guides for the mods. Could you direct me to where they are?




post #1615 of 2703

A nice file with 7 pages of explained mods :



post #1616 of 2703

nice looking.

post #1617 of 2703

Found something interesting with my Muse amp, the solder joints connecting L&R in cracked, re-soldered it and works great.  The sound is fantastic with my Tesla tube now.    

post #1618 of 2703

Just received my G2 with the IR510 mofset today. I am really shocked at the sound quality this little guy puts out.


I am using the stock tube, playing from a cowon x7, and powering a pair of Grado 325i.


I can't wait to roll some tubes in here. Either tonight or tomorrow i'll do a comparison with the G2 vs the Grado RA-1.



post #1619 of 2703

Hello everyone smile_phones.gif,

First, please excuse me for my modest mastery in English, I am French. This is my first post here but I read this forum since very long time.
Here the object of my post: I bought an amplifier Muse MK2 on Ebay. It worked perfectly for a few days and suddenly the red and blue  led have ceased to function.

Since I have a big breath and crackling noise in my headphones and lamp replacement did not solvemy problem.confused_face.gif

Would you which may have caused this failure and how to solve? Thank you.

post #1620 of 2703

Hi trazom,


Changing your tube won't generally solve anything, unless you were using a dead tube or not designed for ...

Did you check that the bias did not change ?


Maybe the problem comes from a single resistor, it may have burn or it's unsoldered.

Could you send macro photos of your amp, around the red led, top/bottom ?

Edited by nanaud - 6/29/11 at 7:42am
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