[UmustBKidn]

  So my recent mod was all about changing the looks of the V2 a bit.  I really did not like the looks of the plexiglass acrylic upper and lower cap.  I purchased some 1/8 inch african mahogany and duplicated the upper and lower caps.  Gives the V2 a bit more of a classy look when sitting on a nice desk.  I'll post a pic when I have it reassembled. 
 
Pics attached.  May not be for everyone, but I like the looks of it.
 
https://flic.kr/p/oqKj36
https://flic.kr/p/oqKruQ

 
Very pretty, I like it!

 

[UmustBKidn]

  At long last, this weekend I had some time to start on modding one of my Bravo V2 amps. Some pics and notes to follow (please see notes at the end)...
 
...

 
Two more items worthy of noting ...
 
1) Make sure to flow each solder joint for a few seconds. I ended up with a cold solder joint somewhere, which left me thinking I had blown the entire project. I revisited each solder joint and reheated them again.
 
2) Make sure you clean the board liberally with 99% alcohol. I mean, really clean it off good. I am not sure but the first try running the amp (which didn't work), the board was still somewhat dirty and littered with rosin.
 
It's worth the trouble to make sure the solder joints are good, and the board is clean.
 
I've been on vacation for a while, but when possible I've been giving the modified V2 a good run-in on my best setup (Modi DAC and Beyer DT770's, with a 50's vintage D-getter Mullard tube). It really sounds good. When I'm fairly confident that my ears have "broken in" to this setup, I'm going to run a little comparison with my other (stock) Bravo V2.

 

[k12azy13astard]

   
"Flying M":
 

 
Hopefully someone can chim in on the brand of this tube? It would be cool to know cause this is another great sounding tube. A+ Marks for clarity, highs and mids. Low end could be a bit better but its very clear. You can hear all the various differences. Quite honestly if you could only have one it would be a close call between this one and the Daystrom. Even Daft Punk sounded groovy. For those two songs the International is hands down the best sound but this guy did quite well for himself. Excellent clarity, mids and hi's. Do Want. 
 

Came across one on ebay after searching for some new tubes for my Bravo. Dunno if anyone posted information on this, but the brand is Westinghouse. Dunno much else on it as I've only come across Yellow label ones (getting a long black right now).

 

[Zeejet]

I know this is an old thread, but I just got one and planning to mod. I did the crosstalk mod since it was the simplest and did not notice any drop in noise at high volumes (although the noise was never that bad at listening levels to begin with). I'm completely new to this and have no background in electronics so please forgive my ignorance. I plan to replace the IRF630s with IRF510s and upgrade the LM317s to LM317ATs. The last thing would be to reduce pop during power-on.
 
Quick question: is it cool to remove/replace the LEDs? I hate the blue/red combo and would rather have only a warm white LED at low brightness instead (to accent the glow of the tube).

 

[rgwrjs]

Well written review. Thank you

 

[UmustBKidn]

  I know this is an old thread, but I just got one and planning to mod. I did the crosstalk mod since it was the simplest and did not notice any drop in noise at high volumes (although the noise was never that bad at listening levels to begin with). I'm completely new to this and have no background in electronics so please forgive my ignorance. I plan to replace the IRF630s with IRF510s and upgrade the LM317s to LM317ATs. The last thing would be to reduce pop during power-on.
 
Quick question: is it cool to remove/replace the LEDs? I hate the blue/red combo and would rather have only a warm white LED at low brightness instead (to accent the glow of the tube).

 
I didn't hear any change from the crosstalk mod, personally. Unclear why anyone thought that was necessary. Given the difficulty I had cutting circuit traces, if I had to do this again, I'd skip that one.
 
Replacing the mosfets will yield better high end response. I also did the caps, and at this point I'm wishing I hadn't ... not entirely sure, but I think I lost some bottom end because of that. Could also be that the increased high end response just makes it seem that way... Please make sure to read all of the caveats about desoldering those, in particular re-flowing the existing joints with rosin-core solder, BEFORE attempting to desolder! That makes a huge difference.
 
LED's: to my knowledge, they actually serve a purpose, beyond lighting. I don't remember exactly what, but I recall reading something about that, in the ton of stuff over at the website where these mods originated (see links earlier in this thread). I suppose you could replace with a different color, but I haven't tried that.

 

[Zeejet]

Thanks for the reply! I got some more wisdom from rockgrotto forums about the LEDs. The blue one can be shorted to turn it off (or replaced with another color), but the red has a forward voltage that is relevant to the circuit. If you can find a way to replicate that forward voltage, you could technically remove it (or replace it with an LED of similar forward voltage such as an appropriate  yellow, orange, or green LED).
 
Finally, I wanted to ask about the soft-start mod (reduction of the popping noise upon ON/OFF). The LED's are slightly dimmer, but the popping sound is still pretty noticeable on the amp. Not sure what others have found.
 
Anyhow this is the list of mods I've done and what I thought of the results:
 
1. Crosstalk reduction; No noticeable difference in noise. I don't think the noise was even noticeable at listening volumes to begin with, so this maybe a situational mod for those experiencing noise from other sources.
 
2. IRL630 to IRF510; Noticeably better extension of highr frequencies and better overall sound. Reccomended.
 
3. LM317 to LM317A; [size=12.7272720336914px]Preventative maintenance mod. [/size]Meant to improve the temperature tolerance since the IRF510's put out more heat? 
 
4. 25V/6800uF to 35V/3300uF Power Cap; Preventative maintenance mod. T[size=12.7272720336914px]he 25V stock cap has very little room for tolerating [/size]fluctuations[size=12.7272720336914px] when being powered by 24V. [/size]
 
[size=12.7272720336914px]5. Soft ON/OFF; This mod only slightly dimmed the LEDs and made no noticeable change in the popping sound from turning the amp ON although the OFF switching is very quiet.[/size]
 
[size=12.7272720336914px]So far mods 2-4 on my list are good calls IMO.[/size]
 
[size=12.7272720336914px]The only two things left that I might try are:[/size]
 
[size=12.7272720336914px]- Replacing the blue LED with a warm white or yellow LED to accentuate the tube glow (which is pretty weak on this amp).[/size]
 
[size=12.7272720336914px]- Replacing the two output caps with 25V/2200uF caps for extension of lower frequencies (I found ones that fit the stock case: [/size]http://www.amazon.com/dp/B004C50U2M/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=1ICLEA5N4KDON&coliid=I1H62W69TXWH9K). I'm really on the fence about this one since I have heard mixed reviews of what this does for the amp. Also, the caps are pricey relative to other parts.

 

[UmustBKidn]

  Thanks for the reply! I got some more wisdom from rockgrotto forums about the LEDs. The blue one can be shorted to turn it off (or replaced with another color), but the red has a forward voltage that is relevant to the circuit. If you can find a way to replicate that forward voltage, you could technically remove it (or replace it with an LED of similar forward voltage such as an appropriate  yellow, orange, or green LED).
 
Finally, I wanted to ask about the soft-start mod (reduction of the popping noise upon ON/OFF). The LED's are slightly dimmer, but the popping sound is still pretty noticeable on the amp. Not sure what others have found.
 
Anyhow this is the list of mods I've done and what I thought of the results:
 
1. Crosstalk reduction; No noticeable difference in noise. I don't think the noise was even noticeable at listening volumes to begin with, so this maybe a situational mod for those experiencing noise from other sources.
 
2. IRL630 to IRF510; Noticeably better extension of highr frequencies and better overall sound. Reccomended.
 
3. LM317 to LM317A; [size=12.7272720336914px]Preventative maintenance mod. [/size]Meant to improve the temperature tolerance since the IRF510's put out more heat? 
 
4. 25V/6800uF to 35V/3300uF Power Cap; Preventative maintenance mod. T[size=12.7272720336914px]he 25V stock cap has very little room for tolerating [/size]fluctuations[size=12.7272720336914px] when being powered by 24V. [/size]
 
[size=12.7272720336914px]5. Soft ON/OFF; This mod only slightly dimmed the LEDs and made no noticeable change in the popping sound from turning the amp ON although the OFF switching is very quiet.[/size]
 
[size=12.7272720336914px]So far mods 2-4 on my list are good calls IMO.[/size]
 
[size=12.7272720336914px]The only two things left that I might try are:[/size]
 
[size=12.7272720336914px]- Replacing the blue LED with a warm white or yellow LED to accentuate the tube glow (which is pretty weak on this amp).[/size]
 
[size=12.7272720336914px]- Replacing the two output caps with 25V/2200uF caps for extension of lower frequencies (I found ones that fit the stock case: [/size]http://www.amazon.com/dp/B004C50U2M/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=1ICLEA5N4KDON&coliid=I1H62W69TXWH9K). I'm really on the fence about this one since I have heard mixed reviews of what this does for the amp. Also, the caps are pricey relative to other parts.

 
I didn't try the pop mod, so no comment.
 
Replacing the LED's was never important to me. I think those are fine as they are.
 
If you do replace the output caps, I'd be interested in your impressions. I have two V2's, one stock and one modified, and when I swap them out, I notice better highs and reduced low end on the modified one. I'd prefer to accentuate the bottom end somehow.

 

[mfish33]

I just did the transistor mods my advise is to use a paper clip heated up to remove the solder from the holes from where you removed the transistors.

 

[David St-Pierre]

Reviving this post...
I just received the Bravo V2, and I was wondering why the volume level was only slightly up, like if the amp was too powerful, even on headphones hard to drive I can't bring the volume up. If I'm not wrong, amps usually need to have their volume to a moderate level for optimal sound quality. Was this a problem for you also? What volume % do you keep your Bravo too? Do the mods change anything to this? Thank you!

 

[yosemitesamiam]

Does anyone know more about the Daystrom Nimchimen 12AU7? I did a Google search and only came up with a Toshiba made valve. Is that right?


I'm listing with Grado SR80i cans, a TCC phono pre and early 70s pioneer TT.

Thanks all!!

Sam

Bravo V2 Review
 
 
Daystrom Nimchimen 12AU7:
 

 
And the bass is back. And back in a big way. I noticed a night and day difference between the Alkaline trio songs - I could hear the feel the baseline in the chorus, the highs were nice and crisp, and the mids were well balanced. Since I bought all the tubes in one big lot I do not know the dollar value on this bad boy but its a keeper. I have 5 of them, and I will defintly keep at least 2 of them. To really notice the difference between this and the stock china unit you just need to listen to the first 25 seconds or so of m.A.A.d city. There is a heavy bassline and some high pitched noises and you can hear them. You can almost feel them laying on top of each other if that makes sense. I was excited as I moved to the DP songs. Again listen to the first 20 seconds or so of Get Lucky and you will never go back to the stock amp. At the end of the first line of the song he gives a low "ughh", it was almost undetectable with the china tube, but there it is nice and clear. Honestly I was grooving in my chair typing this as I was listening. The chorus of Instant Crush is glorious, even though the piano/synth is close to his voice in pitch you can hear it all very clearly, the highs of his voice being above the synth. 
 
RCA "Red Lettering + Clear Top + White Plates" 12AU7:
 
Hrrmmm. I was led to believe the RCA clear tops were quite nice. I am  not sure if this is the one people refer to, but it looks rather similar to some of the online pics, so I am going to assume it is. While it is not as bad as the original china tube its not a whole lot better. We are back in the land of the flat. It gets points for better low end compared to the china unit. The QR songs sounded ok, but were slightly lagging the the Daystrom. The AT songs were way lacking. Definitly still better bass and soundstage than the stocker but pretty meh compared to the Daystrom. I feel like overall this unit is better on the low end and maybe slightly better on the hi's than the stock unit, but its really lacking in the top end. Instant crush was particularly flat, his voice basically smoothes into the chorus if that makes sense. There is a clear lack of resolution. 
 
RCA "Gray Lettering + Mirror top + Gray Plates" 12AU7:
 

 
ahhhhhhhh. This one is super boomy. Quite frankly its even worse than the red clear top. This is really the only way to describe it, it even made Daft Punk sound boomy, like I was listening inside an empty metal building. I ended up trying a second one I had of the same type but it sounded exactly the same. I ended up skipping past most ofthe AT songs cause I couldn't handle the sound. Quite frankly this one annoyed the **** out of me. I dont think I really finished any ofthe 8 songs. 
 
Sherwood Mullard 12AU7A:
 

 
This one takes a while to warm up. It didnt really come alive until the second song (about 5 minutes of run time + 1 minute of pure warm up). However once it came alive it was quite nice. Actually I would say this was eqaul or better than the Daystrom. This was a little more heavy on the low end, and a little less on the hi's but thats not necessarily a bad thing. Excellent clarity, excellent soundstage. In the later parts of the Get Lucky when the other guys sings in the back ground with the animatron voice you can clearly distinguish it from the chorus, perhaps even better than the Daystrom. Both Daft Punk songs were absolutly a joy to listen to with this tube. Bottom line is I will hang onto this one as well. 
 
General Electric 12AU7WA (mil spec) / General Electric 12AU7A:
 

 
 
First thing first. These two sound exactly the same. Perhaps sharper ears are needed to tell the difference, but whatevs. A little flat compared to the Mullard and the Daystrom, but still light years ahead of the stock unit or the RCA tubes. Even daft punk sounds pretty good. A quick search of ebay shows these bad boys can be had for $9-11 shipped any day of the week, if money is your main concern get this tube and leave it be. 
 
Sylvania "Green" 6189 / Sylvania "Yellow" 12AU7A:
 

 
 
 
The queensryche tracks were a little flat. With Alkaline the bass line was a little low, but the vocals and hi's were nice and clear. Its hard to quantify but if The Daystrom and the Mullard are 10/10, and the GE tubes are maybe 7.7/10, this one is like a 7.0/10. Its not bad, and way ahead of the stocker. But having listened to those other tubes first I was definitly spoiled. If I had jumped straight to this one from the stock unit I would have been more impressed. The bass on Kendrick's tracks was not as strong as with the others, and someof the smaller details of the background track was lost. This lack of clarity, or resolution, or whatever you want to call it, is really obvious in the daft punk tracks. The yellow sounded better than the green but not drastically. Enought to notice but it doesnt really change its ranking.
 
International Service Master 12AU7A:
 

 
 
This unit is apparently NOS, and made in germany.  Sweet. This one ranks right up there with the Mullard and the Daystrom. Its a great sounding tube. It a little "warmer" than the rest, everything sounds happier and brighter. The bass is more melodious, good soundstage, just nice. Well balanced. I did not write too much here because I was too busy listeing to the music. 
 
Raytheon 12AU7A:
 

 
 
Also a NOS piece, made in Japan. However thats where the comparison to the internation ends. This one is boomy, better than the RCA grey but not by much. Good clarity but no wow factor. Boomy. Meh. 
 
Hewlett Packard by Memrex 12AU7:
 

 
 
This one looked pretty old and beat, but it delivered a suprisingly melodic sound. Not quite as sweet as the International and not quite as clear as the Daystrom. A good in between, I wouldnt choose it over either of the two, but depending on cost and availability its a great little tube. Alkaline Trio sounded pretty good on this bad boy, so did Kendrick Lamar. Honestly there are not real negatives I can add other than there is a bit of a loss of details, things are not as clear as they are with other tubes. Very solid bass line on the rap tracks. Daft Punk wasnt quite as clear and melodic as others. I guess this one gets left on the roadside as well, just maybe not choking quite so much on dust. 
 
 
"Flying M":
 

 
Hopefully someone can chim in on the brand of this tube? It would be cool to know cause this is another great sounding tube. A+ Marks for clarity, highs and mids. Low end could be a bit better but its very clear. You can hear all the various differences. Quite honestly if you could only have one it would be a close call between this one and the Daystrom. Even Daft Punk sounded groovy. For those two songs the International is hands down the best sound but this guy did quite well for himself. Excellent clarity, mids and hi's. Do Want. 
 
"GM" 
 

 
Again maybe someone can ID the actual maker? Cause its another good one. Very clear hi's, good detail, nice sounds stage. Another keeper. 
 
 
I also have another 10 units I can not ID with anything, so I wont bother with them. If you need any of these tubes let me know cause I have multiple copies of a lot of them. In conclusion the all around winner is the Daystrom, with the Mullard coming in a close second. For a different warmer sound turn to the International Service Master. I am looking forward to doing some mods and getting an even better sound out of this guy, and I will keep you guys updated. 

 

[BigDaddyNC]

Resurrecting this thread...
 
New owner of a Bravo Audio V2 and I credit this thread in part for helping me make the decision.  On the recommendations here I have gotten my grubbies on the Daystrom Nichimen and have an International Service Master on the way.  I also have a Gold Lion waiting in the wings.  
 
Right now I am using the Daystrom and have already noted its superiority to the stock 12AU7 -- need more listening to be able to articulate.  Looks like I'll be having fun over these next two weeks while I am off work.

 

[Maxx134]

I just got this lil baby for Christmas ,

Seems very handy for tube rolling/burn in and very compact size.

Of course because of this thread,
I will need to mod it, lol.
This thread is so well covered it takes all the guesswork out.

I am wondering how this baby will compare and hold up against other units like Vali, vali2 & project starlight/sunrise/horizon.

Although most other amps in this category are either nice hybrids...


Or fake cathode follower tube hybrids, with tubes used like a buffer..
Not actually used in amplification...

Not much choice of class A amp like this one.
Edit: this one is a hybrid as well.
Just found out is it just under the level of a project sunrise.
That's all I found out so far..

This makes a great gift for a nice tiny tube amp.

 

[alonbl]

My Bravo V2 shuts down after it gets warm. Disappointing.

 

[Maxx134]

My Bravo V2 shuts down after it gets warm. Disappointing.

I didn't even turn mine on yet..
Sounds like a thermal problem though.
Did you swap tubes?
I have been looking at other threads and this baby needs some intensive work.
Great for getting your feet wet in diy work,
As the outcome after upgrading is a much better unit.

If you are discouraged at the level of this amp.
Have a look also at this other amp that has potential...



http://www.head-fi.org/t/780178/any-opinions-reviews-on-gemtune-appj-pa1502a/0_20




All these Chinese little amps have great great potential if you want to put your time into it.
The question is which one gives you the motivation to do so...