[Mr Trev]

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.

Kind of surprised to hear you say improved high end detail. I'd think with the way the stock mosfets roll off the high end way early there wouldn't be much hope. But the good thing with the Bravo (and variants) is they do run the tube without negative feedback so it could be that the tube differences are coming through far more than in the Vali2 - I don't actually own 2 of the same tube so I've never been able to compare the 2 amps. No idea about what that B+ cap is about, first I think I've heard of that mod
FWIW - I found the surgical mods are worthwhile

 

[Keno18]

Kind of surprised to hear you say improved high end detail. I'd think with the way the stock mosfets roll off the high end way early there wouldn't be much hope. But the good thing with the Bravo (and variants) is they do run the tube without negative feedback so it could be that the tube differences are coming through far more than in the Vali2 - I don't actually own 2 of the same tube so I've never been able to compare the 2 amps. No idea about what that B+ cap is about, first I think I've heard of that mod
FWIW - I found the surgical mods are worthwhile

It helps the high-end detail vs the stock tube. I wasn't implying the deal was better than the Vali. The B+ capacitor was something I learned about oh, 40 years ago when I worked for Radio Shack and discussed modifyiy a transistor amp with the tech who also worked there. A full mod to the caps would include swapping out the output caps too as you know. The purpose here was to avoid making changes to the pcb proper. Also I was not trying to extend the high frequency response just alter it. The B+ caps do extend the low-end reach not by boosting the lower end, just make it audible.

 

[Geordieboy]

I built my own variant. Works much better than the V2.

 

[Mr Trev]

It helps the high-end detail vs the stock tube. I wasn't implying the deal was better than the Vali. The B+ capacitor was something I learned about oh, 40 years ago when I worked for Radio Shack and discussed modifyiy a transistor amp with the tech who also worked there. A full mod to the caps would include swapping out the output caps too as you know. The purpose here was to avoid making changes to the pcb proper. Also I was not trying to extend the high frequency response just alter it. The B+ caps do extend the low-end reach not by boosting the lower end, just make it audible.

Gotcha. I did replace the output caps during my mods, so I guess I'm already there.
My stock power supply was DOA so I immediately had to replace it so I can't speak for any sound improvements there, but I have been thinking about fabbing up one of those "noise nuke" things.
I really should dig my P1 out of the cobwebs one of these days, but I've gotten sooo spoiled by the auto-bias on my Vali2…

 

[Keno18]

Gotcha. I did replace the output caps during my mods, so I guess I'm already there.
My stock power supply was DOA so I immediately had to replace it so I can't speak for any sound improvements there, but I have been thinking about fabbing up one of those "noise nuke" things.
I really should dig my P1 out of the cobwebs one of these days, but I've gotten sooo spoiled by the auto-bias on my Vali2…

The Bravo V2 has no bias adjustment, I think it uses "grid leak" bias (I'm going to Google that) - the cathode is grounded directly. If you feel in the mood for more mods the B+ cap mod would be good for the P1, it's cap is only 4200 uf. The higher the value the more AC signal gets returned to ground since it's not a balanced circuit. At least that's what I remember. Oh well, something to think about.

 

[Mr Trev]

Actually, I did drag the P1 out. Forgot what a pain it is to bias (you're lucky not having adjustments). First tried a 7dj8 - since it's new and hasn't been in the P1. Epic fail. The lowest I could set the bias voltage was 17.9v. So in went a JJ 6dj8 - just happened to be the next tube I grabbed. I adjust one side up, the other side goes down. Best I could do is ~12.4v (ideally I'd should shoot for 13v). 12AU7s are easier to get biased properly - I suppose the amp is optimized for those types of tubes. After all is said and done, it's still noisy and way freakin loud. An attenuator is pretty much mandatory with my headphones.
Not bad sounding otherwise.

 

[Keno18]

Actually, I did drag the P1 out. Forgot what a pain it is to bias (you're lucky not having adjustments). First tried a 7dj8 - since it's new and hasn't been in the P1. Epic fail. The lowest I could set the bias voltage was 17.9v. So in went a JJ 6dj8 - just happened to be the next tube I grabbed. I adjust one side up, the other side goes down. Best I could do is ~12.4v (ideally I'd should shoot for 13v). 12AU7s are easier to get biased properly - I suppose the amp is optimized for those types of tubes. After all is said and done, it's still noisy and way freakin loud. An attenuator is pretty much mandatory with my headphones.
Not bad sounding otherwise.

I haven't been using my P1 because the muting relay was stuck on and I was just disgusted with it. The other day I knocked it off the table and in the fall the relay works now. Go figure.

 

[Keno18]

So I took the plunge and changed the Mosfets to IRF510s. The top end changed so much that the clear top was too much. Swapped it for the simple 12au7a EH. Now the highs are well articulated and the sound stage is much wider. I guess changing the output caps are next but we'll see as it doesn't sound bad the way it is.

 

[Mr Trev]

So I took the plunge and changed the Mosfets to IRF510s. The top end changed so much that the clear top was too much. Swapped it for the simple 12au7a EH. Now the highs are well articulated and the sound stage is much wider. I guess changing the output caps are next but we'll see as it doesn't sound bad the way it is.

The upgrading the output caps will extend the low range but I doubt you'll find as much of a change as changing the mosfets. Probably the biggest benefit of changing them is to get a higher temperature rating. IIRC the earlier models had a questionably low temp rating - esp. considering they sit right next to a heatsink (at least that's the case with my P1)

 

[Keno18]

Found a home for my old iTunes files. I have about 386 .m4a iTunes files that I bought nearly 10 years ago that I enjoy but not enough to get the uncompressed replacements. So I set up a separate Foobar install just for them. I added a vst plug in called Perfect Declipper that does a good job of restoration on compressed files on the fly and a brickwall limiter that suppresses intersample peaks. Couple that with Foobar's PCM to DSD256 components and the old files sound somewhat descent. The finishing touch was playing them through the Bravo V2 with an rca clear top which added the missing top end most of these files lack. For some reason the modified Bravo with the clear top has a synergistic sound quality with these files. It extends all the way from the top end to the bass frequencies with proper transient attack and decay supplied by Perfect Declipper. All without breathing or other sonic artifacts.

 

[ashleydoormat]

I've got the Dilvpoetry D2 which is similar to the Bravo v2 and I just replaced the power cap to Nichicon 3300uf 50vdc FW and the output caps to Nichicon 2200uf 25vdc KA. My first impression after recap is that the bass is pretty much tamed too much for my liking. I thought replacing the output caps will improve the bass so is it just about burning in the caps? Also the new output caps are a bit too tall for the acrylic top is there anyway to mod the top (without cutting holes) to make it fit?

 

[Keno18]

I've got the Dilvpoetry D2 which is similar to the Bravo v2 and I just replaced the power cap to Nichicon 3300uf 50vdc FW and the output caps to Nichicon 2200uf 25vdc KA. My first impression after recap is that the bass is pretty much tamed too much for my liking. I thought replacing the output caps will improve the bass so is it just about burning in the caps? Also the new output caps are a bit too tall for the acrylic top is there anyway to mod the top (without cutting holes) to make it fit?

What was the original value of the power cap? In the Bravo it's 6800uf. Reducing the value of the power cap will reduce the bass and lower the ability to respond to transients in the music. Increasing the power cap will also increase the amps ability to play lower frequencies. It will not boost the bass, just better extention. An additional cap placed across the b+ will have the same effect as making the power cap larger. I made a separate box that holds the additional 2200uf cap that the power brick plugs into.

 

[ashleydoormat]

The original power cap was Nover 3300uf 50v and output caps were KY 1000uf 25v. I wanted to keep the cap size mostly the same to retain the aesthetic of the amp.
Question 1 : is burning in cap a thing?
Question 2: can i buy longer metal posts from hardware store to install the acrylic to over the taller output caps?

Thanks!

 

[Keno18]

The original power cap was Nover 3300uf 50v and output caps were KY 1000uf 25v. I wanted to keep the cap size mostly the same to retain the aesthetic of the amp.
Question 1 : is burning in cap a thing?
Question 2: can i buy longer metal posts from hardware store to install the acrylic to over the taller output caps?

Thanks!

I got my extentions from Amazon. 3300 is pretty anemic. You should at least be able to increase it to at least 4700 without changing the height. Burning in caps at this size shouldn't be needed.

 

[ashleydoormat]

Ok. So the bass is back after burning in. I left it playing for hours yesterday and today the bass is punching again (what do I do with techno and deep house without the bass lol). It's my second soldering project (I learn soldering just to mod this amp!) so I hope I didn't mess up anything! I chose the same valued power cap as the original cap based on what solderdude posted here. And here is the pdf I found on that site which summed up most mods of the v2. Here's a list of guides modding similar amps from the site:
http://www.mediafire.com/file/tef7pnitixakzaa/Bravo+Ocean+schematic+modifications.pdf
http://www.mediafire.com/file/648rn66jncce788/modifying+the+Indeed+G2+amplifier(g).pdf
http://www.mediafire.com/file/vzdwnrlnjjz/modding+of+a+Miridiy+amplifier.pdf