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Post by Coolmeadow Kid on Jul 27, 2014 3:32:11 GMT
Ok, looking at the modifications for my Bravo V2. And seeing that if I did all of the mods, there are really very few remaining pieces, resistors, input connectors, volume pot, tube base and some passive cooling fins, needed to build a complete amp.....and some of those items could probably be re-purposed from some defunct stereo gear. So why not duplicate the amp with better components and leave the V2 intact? I don't think I'd want to etch a new board, but what about using some protoboard that is larger, use solid core insulated wiring (or even stranded insulated wire) held in place by hot glue after the soldering is done. Follow the same path as an etched board so no overlapping of wiring. Solder components to the wire like you would a trace by cutting the insulation away at that small spot. Would probably need to use silver wire instead of copper to keep corrosion down (I guess you can still buy this?). Would allow for larger spacing for larger heat sinks and for air space around the heat producing objects.
Like I said, bring me back to reality. There has to be a reason this wouldn't work. Jim.
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Rabbit
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Post by Rabbit on Jul 27, 2014 5:20:48 GMT
Hi Jim. The Bravo has really poor crosstalk figures. Solderdude described a really easy test for this which shows just how poor it is.
Disconnect one channel at the back and play music. On loud sections, listen and on the side that's disconnected, you will hear a lot of interference; especially on peaks.
Therefore, to really improve the amp, this needs redesigning. The heat build up is very destructive so adding a larger heat sink would prolong it's life.
Just upgrading the components wouldn't fix the issue of crosstalk and also the other issue that it has in lack of treble extension. That's why mods are a little more involved.
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Post by Coolmeadow Kid on Jul 27, 2014 14:57:16 GMT
Hi Jim. The Bravo has really poor crosstalk figures. Solderdude described a really easy test for this which shows just how poor it is. Disconnect one channel at the back and play music. On loud sections, listen and on the side that's disconnected, you will hear a lot of interference; especially on peaks. Therefore, to really improve the amp, this needs redesigning. The heat build up is very destructive so adding a larger heat sink would prolong it's life. Just upgrading the components wouldn't fix the issue of crosstalk and also the other issue that it has in lack of treble extension. That's why mods are a little more involved. Hi Ian. Yes the Bravo and like amps are made like crap, and therefore have multiple issues. I failed to mention that I did perform the crosstalk mod as Frans and others have recommended in multiple threads on at least 2 if not 3 forums. I followed the illustrations that Oohms provided at one of the other forums. Works great, no distortion when I use the balance feature on my computer audio control window now. I also believe I have fixed the heat situation for my V2 by building a wood enclosure that is open at the bottom sides to allow access to controls and connections, and incorporates an 80mm computer fan in the top blowing air down onto the components. The top is removed from the amp. I listened to the amp for 4 hours yesterday afternoon and all during that time, I could put my fingers on the heatsinks and they were barely warm to the touch. I'm hoping that this will stave off the early death that most experience for this amp. Which brings me back to my original question....Would it be feasible to build an amp of this design, incorporating most if not all of the modifications Frans recommends, on a larger protoboard that would allow space for larger heatsinks and larger capacitors that just doesn't exist on these cheap production amps? If I could scavenge some items like headphone output jack, power switch, RCA input jack from a defunct audio cassette deck, the additional items needed over the modification parts would be minimal in cost. Even if I purchased these components it would not be much in the grand scheme of things. But would it be a workable, possibly longer lasting option versus modifying a V2 circuit board with the inherent soldering issues? Thanks! Jim. |
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solderdude
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Post by solderdude on Aug 2, 2014 9:39:24 GMT
Ok, looking at the modifications for my Bravo V2. And seeing that if I did all of the mods, there are really very few remaining pieces, resistors, input connectors, volume pot, tube base and some passive cooling fins, needed to build a complete amp.....and some of those items could probably be re-purposed from some defunct stereo gear. So why not duplicate the amp with better components and leave the V2 intact? I don't think I'd want to etch a new board, but what about using some protoboard that is larger, use solid core insulated wiring (or even stranded insulated wire) held in place by hot glue after the soldering is done. Follow the same path as an etched board so no overlapping of wiring. Solder components to the wire like you would a trace by cutting the insulation away at that small spot. Would probably need to use silver wire instead of copper to keep corrosion down (I guess you can still buy this?). Would allow for larger spacing for larger heat sinks and for air space around the heat producing objects. Like I said, bring me back to reality. There has to be a reason this wouldn't work. Jim. It would work BUT there are some possible issues. When Jeremy (Garage 1217) contacted me he wanted to do the same (just build a better version with mods) but persuaded him to further improve the design. The Sunrise was the result. Of course you can make a point to point wired Bravo clone (with mods) with larger heatsinks and caps placed further away from heat sources. Making a proper star ground would need to be considered in this case as wiring it wrong could result in strange behaviour. Instead of copying a (somewhat too basic) and flawed design I suggest to build the Sunrise or Horizon instead. You could even implement the auto-bias or auto heater select of the Ember with some modifications. Proid also made some home-made amps: diyah.boards.net/thread/384/hybrid-amp |
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Post by Coolmeadow Kid on Aug 2, 2014 14:46:52 GMT
Thanks Frans, I think that answered my main question about the feasibility of me doing something like this... Leave it alone!  I can follow step by step instructions, but I have absolutely no understanding of the electronic "hows and whys". Which leads to another question....what is a "proper star ground"? I can duplicate a pattern, but I can't develop it on my own. Are there any online pattern and parts lists that you know of? I like tinkering with stuff like this, but for me it is kind of like cooking. I can follow a recipe, but don't ask me to come up with a new one. Thanks to both of you guys for the guidance. Jim. |
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Rabbit
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Post by Rabbit on Aug 2, 2014 17:58:39 GMT
Yeah ..... Let it burn!!! Horizon and Sunrise are streets ahead. I had different versions of the Bravos at the start. I liked the 'sound' of them a lot but every one of them burned out within a year. |
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Post by Coolmeadow Kid on Aug 2, 2014 18:40:36 GMT
I'm hoping heat is the only thing that kills these amps. If so, I think I have that fixed with my wood enclosure and 80mm fan blowing down on the amp, top acrylic plate removed. If not, I'll do the upgrade mods and see if one of those components is what died. I did the crosstalk mod, made a huge difference. Guess I need to see if the tube I was listening to before the change and RCA clear top install sounds better. Thanks again! Jim.
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Deleted
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Post by Deleted on Aug 2, 2014 20:55:16 GMT
I'm hoping heat is the only thing that kills these amps. If so, I think I have that fixed with my wood enclosure and 80mm fan blowing down on the amp, top acrylic plate removed. Jim, I have little knowledge of electronics, however, if I learned one thing from RG, it was that cheap components (probably of the wrong heat-rating for their position), working at their limit, and being cooked at the same time equals short life-span. Jeff |
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Post by Coolmeadow Kid on Aug 2, 2014 22:07:15 GMT
Yes, and I can totally understand that. I'm just hoping that is all the issue is, not that the cheap components or the inherent design itself with or without the heat issue, also equates to an early death. I've run mine with the 80mm fan on for 4 hours listening to music, and the heat sinks are barely warm to the touch. I will still eventually do the mods just to get the better frequency response even though my ears probably roll off not too much higher than the stock Bravo V2 does.  But for the time being the music I'm listening to doesn't suffer too much from the rolled off top end. (A Capella...Pentatonix specifically, although some of the offerings from Glad, Eclipse6, Home Free and MO5IAC are pretty good also) Thanks for the confirmation about heat being the killer. Guess I'll see how long this one lasts with the fan on it. Jim. |
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Post by MrEss on Oct 29, 2014 20:02:30 GMT
IMO, the lifespan issues are all in the (poor) implementation. It's too much heat, and the poor quality components that are more sensitive to that heat.
I'm listening on a G2 right now, and I'm really happy with it -- but only after heavy modification to make it sound better and run cooler. It's lasted about 18 months so far, running 8 or so hours per day at my desk.
The various higher-quality hybrid amps now available have totally eclipsed the stock or lightly-modified G2. Project Starlight, Schiit Vali, and others are all beautiful and work without "mandatory" mods. The best thing about the G2 today is that it's a cheap starting point for a project -- if you are looking for a project instead of an amplifier.
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solderdude
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Post by solderdude on Oct 30, 2014 15:41:06 GMT
The various higher-quality hybrid amps now available have totally eclipsed the stock or lightly-modified G2. Project Starlight, Schiit Vali, and others are all beautiful and work without "mandatory" mods. The best thing about the G2 today is that it's a cheap starting point for a project -- if you are looking for a project instead of an amplifier. That's indeed the proper way of looking at it. When you want to have a project on your hand that won't break the bank if you break it then these Chinese amps are fun. When you are looking for a kit or ready made/commercial amp with a good quality / sound there are plenty of options available. |
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I can follow step by step instructions, but I have absolutely no understanding of the electronic "hows and whys". Which leads to another question....what is a "proper star ground"?
But for the time being the music I'm listening to doesn't suffer too much from the rolled off top end. (A Capella...Pentatonix specifically, although some of the offerings from Glad, Eclipse6, Home Free and MO5IAC are pretty good also) Thanks for the confirmation about heat being the killer. Guess I'll see how long this one lasts with the fan on it. Jim.