Bravo Audio - funny looking little tube amps | Page 57 | Headphone Reviews and Discussion - Head-Fi.org

lawrywild · May 27, 2010 at 9:51 AM

Ok cool, I did some googling and apparently the 12AU7's are self bias adjusting..

Now, only had it a few days but already I'm thinking about the mods to do.

Atm I'm thinking...

Replace Shu Guang with Mullard tube
Replace the brown (chemicon?) caps with Panasonic FMs (think I have some low ESR 25v 1000uF already)
Replace the RCA inputs with gold plated, non skeletal ones.
Resolder the tube socket since it doesn't lie flat on the PCB atm and not all pins are coming through the back of the PCB.
Resolder 3.5mm input as it's same problem as above.
Maybe swap the 6.3mm output with something with gold plated contacts.
Replace MOSFETs with IRF510 or IRL530

Sound good? Anything else?

How are the Rubycon smaller black caps?

What's the volume pot like? Worth changing? I can't seem to detect much channel imbalance, only the left channel is very slightly louder when the pots turned right down I think..

Joe Presto · May 27, 2010 at 5:41 PM

After contacting the ebay seller (smxsky) regarding the noise in the amp, he asked me to check something, and after that he let me know that a new one is on the way! Can't wait to hear the replacement...

He asked me to remove the bottom acrylic cover and touch 2 pins with a metal object and report the results. The pins correspond with the trim-pots, when touching either one with something metal, the noise in the amp increased; based on this he is sending me a new one (less tube and power supply). Does this mean that the trim-pots are faulty? I could potentially swap those out and mod that amp further, leaving the other one stock.

Judge Buff · May 27, 2010 at 10:57 PM

Joe, you've been given Carte Blanche to mod a free V2! Congratulations! I'd start with the output caps and follow all the recommendations in this thread.

Quote:

joe presto said:
After contacting the ebay seller (smxsky) regarding the noise in the amp, he asked me to check something, and after that he let me know that a new one is on the way! Can't wait to hear the replacement...

He asked me to remove the bottom acrylic cover and touch 2 pins with a metal object and report the results. The pins correspond with the trim-pots, when touching either one with something metal, the noise in the amp increased; based on this he is sending me a new one (less tube and power supply). Does this mean that the trim-pots are faulty? I could potentially swap those out and mod that amp further, leaving the other one stock.

Joe Presto · May 28, 2010 at 3:53 AM

True, though I will first need to fix the sound before trying to improve it! I'll start with the caps, but will exchange the trim-pots too, I don't trust them!

EDIT: It's not the V2, I hope he doesn't send a V2, as I don't have a tube then O.o

Quote:

judge buff said:
Joe, you've been given Carte Blanche to mod a free V2! Congratulations! I'd start with the output caps and follow all the recommendations in this thread.

Joe Presto · May 29, 2010 at 9:18 AM

Judge Buff, I saw you mentioned replacing the trim-pots with Bournes ones, did they work for you? I'll be re-reading the thread to see what else can be replaced, there is quite a lot scattered throughout this thread. Need to be careful though, my lack of soldering skills just killed my already butchered SR60's whilst replacing a faulty cable :frowning2:

caceledon · May 30, 2010 at 1:10 PM

I found on Ebay a Bravo V2 Clone by MUSE http://cgi.ebay.com/MUSE-Class-Hybrid-Tube-Headphone-Amplifier-6N11-NEW-/120576181081?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item1c12e68359 has anyone tried it yet? It has a buy it now of 50 vs the 65 that the bravo currently has, and the specs look good, so I´m tempted. What do you think?

HiGHFLYiN9 · May 30, 2010 at 1:57 PM

You may want to run a quick Google search on MUSE quality control :wink:

I was briefly looking at one of their products and quickly changed my mind, FWIW.

Avro_Arrow · May 30, 2010 at 2:14 PM

All of these little tube hybrid amps come from the same contract
manufacturer in China. I've seen them go by three or four different
names. They are made in batches and this one seems to be a
leftover version one Bravo. Quality on this run was poor. Later
amps were a little better, but not much. What can you expect
from a factory that pays its workers about a dollar a week?

Quote:

caceledon said:
I found on Ebay a Bravo V2 Clone by MUSE http://cgi.ebay.com/MUSE-Class-Hybrid-Tube-Headphone-Amplifier-6N11-NEW-/120576181081?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item1c12e68359 has anyone tried it yet? It has a buy it now of 50 vs the 65 that the bravo currently has, and the specs look good, so I´m tempted. What do you think?

Judge Buff · May 31, 2010 at 12:01 AM

Quote:

joe presto said:
Judge Buff, I saw you mentioned replacing the trim-pots with Bournes ones, did they work for you? I'll be re-reading the thread to see what else can be replaced, there is quite a lot scattered throughout this thread. Need to be careful though, my lack of soldering skills just killed my already butchered SR60's whilst replacing a faulty cable

Yeah, Bourne makes good trim-pots. The ones I put in are only single turn. Since I installed the bias caps, the single turn pots are not precise enough for me to do the final bit of adjustment easily. I have ordered multi-turn Bourne 2k pots to replace them.

caceledon · May 31, 2010 at 10:39 PM

I just bought a bravo V2 on Ebay (for $70, I know quite expensive). This comes with a 12AU7 tube, and since I´ve never had any tube amp before, and have always heard that you have to change the tubes, I went a little crazy buying tubes on Ebay (different types 12AU7A, E88CC, 6922, 6DJ8, CN1P, 6963, CCa). But know I have doubt if they will work on my amp, since some of the most expensive are 6922, and not 12AU7 as the one that came with the amp. Have I wasted a lot of money in vain????

azncookiecutter · May 31, 2010 at 11:11 PM

Just put in a Mullard 12AU7 in the Bravo, a nice improvement over the stock Chinese 12AU7. A lot smoother sound, for an initial impression.

Joe Presto · Jun 1, 2010 at 3:14 AM

As far as I can tell, the E88CC, 6922 and 6DJ8 won't work in your Bravo (V2); those are all very similar and work in the first generation Bravo amps; you certainly haven't wasted your money, you could make some fellow head-fiers very happy, put them in the FS section and see how you go! Which ones did you get?

Quote:

caceledon said:
I just bought a bravo V2 on Ebay (for $70, I know quite expensive). This comes with a 12AU7 tube, and since I´ve never had any tube amp before, and have always heard that you have to change the tubes, I went a little crazy buying tubes on Ebay (different types 12AU7A, E88CC, 6922, 6DJ8, CN1P, 6963, CCa). But know I have doubt if they will work on my amp, since some of the most expensive are 6922, and not 12AU7 as the one that came with the amp. Have I wasted a lot of money in vain????

levlhed · Jun 1, 2010 at 12:59 PM

6DJ8/6922 family will def. NOT work in the V.2 which uses the 12AU7 family.
Don't fret though. Tubes don't go DOWN in value, so just hold onto them. Trust me, now that you've gotten started down this road you'll eventually have a need for those tubes :wink:

I just took delivery of a used Sola SLS-24-024T for my V.2
I'm still not entirely sure how to hook it up, but since the Bravo is still making it's way to me I have some time.....

HiGHFLYiN9 · Jun 1, 2010 at 4:13 PM

Right, the E88CC, 6922 and 6DJ8 are all incredibly common on tube audio gear, especially anything that has a tube buffer. Because of that, the demand for good NOS tubes in that family is quite high. I prefer amps using the 12AU7 tube because you can get relatively good ones for $20 a pop. Good 6922s are quite a bit more.

If you got any 5814 / 5963 or ECC82, I believe they are similar specs to the 12AU7, but you may want to wait for an expert to confirm that :wink:

Gubretti · Jun 1, 2010 at 4:27 PM

Any word on the V3 version? It looks intriguing, I was thinking of getting the V2 but I already have some ECC88 tubes so I'm either getting the V1 Deluxe or V3.

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