[BigDaddyNC]

I tried out the Genalex Gold Lion in the Bravo V2.  These are preliminary observations as the tube could probably use some more "breaking in" as it were.
 
First impressions were that it was bright as compared to the Daystrom.  I noticed it mostly on cymbals.  There was less bass.  What bass that was there was nice, but outside of classical music I found it to be lacking.  Overall presentation was clean and clear, soundstage adequate but not great.
 
I put in about 15 hours with the tube.  I went back to the Daystrom Nichimen and still like it much better.  Having said that, I will put the Gold Lion back in soon and do some extended sessions to see if that Golden Lion will open up.

 

[alonbl]

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...

 
I tried it with a different tube but the result was the same. 50$ down the drain.
I just bought the Schiit Modi+Magni (uber edition) and I'm very happy

 

[Warven]

Hello all, sorry to dig this thread up, but I have a question regarding the crosstalk mod I did on my Bravo audio v2.
 
I have a awful lot of static when turning the volume up (and I had to turn it up or I would hear anything on my DT770 Pro 250 ohms), and so I thought doing the crosstalk mod would reduce this. Instead I still have static on high volume level, but now I only need to turn the knob a quarter of a turn to reach sufficient volume level (instead of half a turn before, where the static would appear). 
So all in all my problem is fixed because I can use it without the static between tracks, but I wonder if this is expected when doing the mod ?
 
Cheers,

 

[Sp12er3]

I've been looking around for an upgrade tube for my Ocean (stock), and found a couple:
RCA 12au7 Black Plate Square Getter
RCA Black Plate Triple Mica Square Getter
Electro Harmonix + (Glod ver)
Sylvania Rebranded National
Toshiba (long and short grey plate) Japan
Matsushita Japan
Trigon England (made by RFT Germany)
The United States RCA three square black mica ring
The United States RCA Straight tube ( a couple type)
USA tube GE5814
Raytheon 12AU7 British descend Orange lettering
Poison sound RCA black double tube steel column
Fullmusic 12AU7 gold plated
Genalex Gold Lion
JJ ECC82
PS VANE MKII
a couple Shuguang (basically tons of new Chinese made one, seems sucks?)

Does anyone have experience with any of these? I have the pic for them as well to make sure if it's the same. Aiming for similar mid forwardness to stock but still have better control over the whole spectrum (kinda a bit messy right now), also, does any change from stock can be constituted as an Upgrade?

 

[Sp12er3]

do some extended sessions to see if that Golden Lion will open up

How does it ended up being?

 

[LeaUK]

Hi all. As I can't start a new thread, hope you don't mind me bringing this one back to life?

Firstly I just wanted to thank the many original v2 modding enthusiasts for sharing so much useful information and for their detailed and dedicated input to the Bravo V2 mods. I've just got back into audio and being an ex EE was attracted instantly to the Bravo v2 and mods. Mods I see have been talked to death and I've read many many pages, with almost information overload and have a mod plan, but still a couple of questions are outstanding. I'm using HD 580's 300R impedance.

I've also included part links as this was one thing I failed to locate through forums and I spent HOURS searching (bear in mind I'm not familiar with Hi-Fi part sellers so lots of searching, oh and I'm UK based) - so I hope this helps others too.

Plan (based on solderdude's recommendation and mine beginning 0.x).

Questions:

1. After completing the mods listed below, is it still worth changing the tube? I'm thinking:
GE 5 Star NOS 5814A - any thoughts appreciated.

2. Bias adjust - ref: i157.photobucket.com/albums/t69/pinkfloyd2007_bucket/bias.jpg

My v2 version doesn't have the trimmers, seems to have 25k resisters instead (25k is what the pcb states, however they are actually 24k).

So where to fit the presets, between which pins, and what are the 24k resistors for?

13.5v for IRF510s

measured at L220 and R220 photobucket.com/gallery/user/pinkfloyd2007_bucket/media/bWVkaWFJZDozMTgwMTcyNQ==/?ref=

3. Date codes for GE 5 Star tubes? I've seen a few on eBay with the code MZ 188-5 Green and grey print. Going on this information:

While I worked at Cain, we had a list of the two letter codes, and we were at the middle of the alphabet for the two years I worked there. G, H and K were the common second letter - they were the manufacture years 81, 82 and 83. The first letters were a simple A-M that stood for the month of manufacture.

Also, the months were labelled different for different years, even vs odd perhaps. A-M and N-Z or thereabouts were the two month groups, always ascending. So, AL or NL was a January, 1983 tube, depending on the month code group for 1983.

www.videokarma.org/showthread.php?t=134068


So far I understand the 188-5 means GE and Owensboro Kentucky was the plant of manufacturer. MZ is possible Month/Year ..which would be August 1983? Is this correct?

UPdate - now if GE used the same as its appliance division:
products.geappliances.com/appliance/gea-support-search-content?contentId=16195

July 1988 or 1976 - I wonder how we tell when year codes roll?


So much conflicting information - thanks to anyone who comments.


The most sound changing in order of magnitude:


0.1: I've added a valve change to my list based upon the tube rolling thread:
www.head-fi.org/threads/bravo-v2-review-tube-rolling-mods-coming-soon.671688/

GE 5 Star NOS 5814A - any thoughts appreciated.

1: IRL510 (highs extension)

cpc.farnell.com/vishay/irl510pbf/mosfet-n-logic-to-220/dp/SC11134?ost=IRL510PBF&scope=partnumberlookahead&exaMfpn=true&searchref=searchlookahead&ddkey=http%3Aen-CPC%2FCPC_United_Kingdom%2Fw%2Fsearch

2: crosstalk cut

3: bias voltage setting (depends on tube)
- add 5k and 1k in series
cpc.farnell.com/multicomp/mf50-1k/resistor-0-5w-1-1k/dp/RE05031?ost=RE05031&scope=partnumberlookahead&exaMfpn=true&searchref=searchlookahead&ddkey=http%3Aen-CPC%2FCPC_United_Kingdom%2Fw%2Fsearch

cpc.farnell.com/bourns/3309p-1-502/trimmer-5k-9mm/dp/RE05264?ost=RE05264&scope=partnumberlookahead&exaMfpn=true&searchref=searchlookahead&ddkey=http%3Aen-CPC%2FCPC_United_Kingdom%2Fw%2Fsearch

4: heater mod (distortion reduction)
- need to research this more, is it supply heater tubes with analogue based PSU?

5: output resistance change. - change to 27R to provide approx 10:1 output balanced drive (300R:27R)
cpc.farnell.com/multicomp/mf50-27r/resistor-0-5w-1-27r/dp/RE05010?ost=re05010&ddkey=http%3Aen-CPC%2FCPC_United_Kingdom%2Fsearch

6: output caps
- change to NFG-890 - 2200uF 35V FG Nichicon type, UFG1V222MHM (Fine Gold)
www.hificollective.co.uk/catalog/nfg890-2200uf-nichicon-type-ufg1v222mhm-p-5323.html

7: input caps
- not really sure about these, both due to construction and worthiness (listed last on the priority list)
cpc.farnell.com/cornell-dubilier/cd19fd102fo3f/capacitor-1-0nf-500v/dp/CA05880?pf=110014722&anyFilterApplied=true&capacitance=1000pf&ddkey=http%3Aen-CPC%2FCPC_United_Kingdom%2Fc%2Felectronic-electrical-components%2Fcapacitors%2Fsilver-mica-capacitors


Non-Sound:

1: LM317 to LM317AT - Three-Terminal Adjustable Regulator - LM317AT
cpc.farnell.com/texas-instruments/lm317at/v-reg-adj-1-2-37v-to-220-3-317/dp/SC08257?ost=SC08257&ddkey=http%3Aen-CPC%2FCPC_United_Kingdom%2Fsearch

2: Replacement heatsink for LM317AT - Heat Sink, TO220/218, 12.9°C/W - 6391BG
cpc.farnell.com/aavid-thermalloy/6391bg/heat-sink-to-220-218-12-9-c-w/dp/SC10867?ost=6391BG&ddkey=http%3Aen-CPC%2FCPC_United_Kingdom%2Fsearch

Thermal paste: Heat Sink Compound 25g Tube - 200001000 25GM
cpc.farnell.com/servisol/200001000-25gm/heat-sink-compound-25g-tube/dp/SAHEATSINKCOMP?ost=200001000+25GM&ddkey=http%3Aen-CPC%2FCPC_United_Kingdom%2Fsearch

3: Power supply cap (exceptionally low ESR) - Panasonic Electrolytic Capacitor, 4700 µF, 35 V, AM Series, ± 20%, Radial Leaded, 18 mm - ECA1VAM472X
cpc.farnell.com/panasonic-electronic-components/eca1vam472x/capacitor-4700uf-35v/dp/CA05753?ost=CA05753&scope=partnumberlookahead&exaMfpn=true&searchref=searchlookahead&ddkey=http%3Aen-CPC%2FCPC_United_Kingdom%2Fw%2Fsearch

Bought 2 so may put these in parallel - not sure if that's a real requirement as I would imagine the low ESR and voltage lift is the crux of the mod?

4. Switch - really struggling to find a 8mm width >1.5A SPDT with toggle left to right, ended up with a 12.5mm DPDT (gold contacts, gives 10A ish if used in parallel) so may have to offset forward slightly to avoid the input cap. Panel Mount Toggle Switch, DPDT, On-On, 5A, Gold Contacts - 1MD1T1B1M1RE.
cpc.farnell.com/multicomp/1md1t1b1m1re/switch-dpdt/dp/SW02854?ost=SW02854&scope=partnumberlookahead&exaMfpn=true&searchref=searchlookahead&ddkey=http%3Aen-CPC%2FCPC_United_Kingdom%2Fw%2Fsearch

Note: due to the heatsink and caps we need to raise the top perspex plate:

5. Nickel plated M3 spacer - Spacers M3 / 10mm, 25 Pack - R30-3001002
cpc.farnell.com/harwin/r30-3001002/spacers-m3-10mm/dp/PC00099


Lea


REF:
rockgrotto.proboards.com/thread/7751#ixzz55TQ9aBAC
rockgrotto.proboards.com/thread/5297?q=irl510
rockgrotto.proboards.com/thread/5297

www.head-fi.org/threads/bravo-v2-review-tube-rolling-mods-coming-soon.671688/


Schematic - although not 100% identical to the Bravo V2
cdn.head-fi.org/a/7194711.jpg



Read more: http://rockgrotto.proboards.com/thread/11555/bravo-v2-modifications-2017#ixzz55axTo6pW

 

[Mr Trev]

I have a modded a Little Bear P1 (which is basically the same as the Bravo). I upgraded to the IRL 510, upgraded the output caps, replaced the volume pot. with a log. type. I also ended up replacing the socket with a Belton(?) - I found the contacts on the stock socket rather flimsy, and had to replace the power switch because it simply fell apart.

As far as using a different tube, if you're comparing it to the stock 12au7 it comes with, absolutely replace it. Pretty much any NOS tube will sound better. One thing to keep in mind is these amps may be very rigid on heater current - 300 ma. (at least mine was) I tried using a 5670 which has a 350ma rating and couldn't even adjust the bias properly. As long as you stay in the 12au7 (or 6dj8 if your amp can do 6v tubes too) family you should be OK.

I never tried the heater current mod - a little too much effort/skill required for me.

If you need more help or advice be sure to check out DIYaudioheaven. Solderdude is active there and he was quite helpful when I was modding mine

 

[LeaUK]

Hi Mr Trev

Great advice, many thanks. Based on this I'll change the tube as see (hear) what happens.

I've headed over to http://diyah.boards.net/thread/edit/1821 thanks for the tip!

Cheers
Lea

 

[UmustBKidn]

A few years on... both of my bravo amps are still running, though I am about to replace them with a newly ordered Bottlehead Crack.
I still have some tubes I bought on ebay for that amp that Ive never unboxed, so it should be lots of fun ...
I see there is now a Bravo V3 in play. No idea what that sounds like, nor am I going to try.
This is about all I wanted to do on these amps. They will soon be placed in long term storage, to be unearthed by my children after my demise...

 

[Sp12er3]

They will soon be placed in long term storage, to be unearthed by my children after my demise...

haha that's a nice way to end it, tho agree what this little novelty is too cheap to be sold over and over, might as well make use of it for some more fun.
Also, the V3 is actually pretty old already, it uses different design if i remember correctly.

 

[Ad720]

New Bravo V2 owner here. Thanks all for the info in this thread. While I'm waiting for some more mod components, as well as a GE 5814, to come in I dug through my parts drawer and found a GE JAN 5965, which I believe is a 12At7 equivalent. I popped it in and wow, super punchy and in your face. It's old and noisy and microphonic but still fun. Really looking forward to jumping into tricking out this fun little amp.

 

[Geordieboy]

I built my own version with a few other mods

 

[UmustBKidn]

haha that's a nice way to end it, tho agree what this little novelty is too cheap to be sold over and over, might as well make use of it for some more fun.
Also, the V3 is actually pretty old already, it uses different design if i remember correctly.

Sp12...

I don't mean to diss Bravo. They served me well for a long while. It remains in my mind a wonderful way to start this journey. But my newly assembled Bottlehead Crack is far superior, to my ears... when I can hear.

A side note in case you don't know... I've had some serious issues with my hearing over the last year, which may have been the result of two car accidents (neither my fault). In Nov. 2017 I was rear ended at freeway speeds, and in Jan 2018 hit head on by a drunk driver, who ran a red light. For several months now (since 12-18) I've been getting random attacks of Vertigo, usually accompanied with hearing loss in my right ear. I can only attribute this to physical damage caused by trauma. Not that my ears were perfect to start with... I'm not a young man, and stuff like this puts a serious dent in my ability to enjoy this hobby. I am not a quitter and I am determined to find help; I'm seeing the best ENT in town in 2 weeks (though I have already stumped another ENT and my PCP).

That said I think the Bravo's are the best game in town for 70 bucks. If you have $300 to spend and can solder and use a DVM properly then the Bottlehead Crack is superior. Period.

 

[Sp12er3]

of course, of course, that's nice to know man, upgrade away.
Pray you have good luck on your endeavor

 

[Keno18]

I just made three non-surgical mods to my Bravo. Actually I made them awhile ago but just did critical listening tests vs the Schiit Vali 2 recently with HD6XX HP. The three mods are: 1. Replaced the stock ps after trying 4 others with the LEDWHOLESALERS 24v 2.5 A ps it actually improved the low-end. 2. Added an additional 3300 uf cap on the b+ in an outboard box. Brings the total capacitance on the B+ to 10,100 uf. 3. Then swapped out the stock tube with an rca clear top 12au7a. These last two increased the low-end reach and better defined the high-end. The result is a much improved bass-slam and high-end detail. When compared to the Vali 2/6sn7 the sound quality is not better or worse but different in a good way. Not as delicate or refined but more forward and attention-getting. It gives me a choice now as to how I want to hear my music without giving up fidelity.