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Post by magicwolf on Aug 19, 2013 7:23:06 GMT
Hi, I have a similar amplifier:
Don't prompt what finishings (mods) it is possible to make with it?
Thanks!
)
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Post by magicwolf on Aug 19, 2013 10:21:58 GMT
I ask about the modification...
I already bought this amp and would like to improve it.
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Post by magicwolf on Aug 19, 2013 10:41:37 GMT
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Post by Deleted on Aug 19, 2013 11:03:31 GMT
magicwolf
Are you able to post a schematic diagram, or a list of components so that members can make suggestions ?
Alex
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Post by magicwolf on Aug 19, 2013 15:00:51 GMT
Unfortunately, I have no scheme. I can't request the scheme from the seller as bought on taobao by means of mistertao (_item.taobao.com/item.htm?id=9688466623_). I already repaired this board and to me told that the scheme of the amplifier is similar to this:  I will make the list of the main components. |
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Post by magicwolf on Aug 29, 2013 6:18:43 GMT
I asked, and experts have drawn an electronic amplifier circuit: s2.ipicture.ru/uploads/20130829/3Qx73WZR.jpgUnfortunately, I have a faulty tube. It is set at (1) 14v, then the point (2) have a single channel 12.3v, another 10.8V. Rewired from one channel to another and IRF630 2N3906 - did not help. |
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Post by paradoxa on Sept 19, 2013 10:43:07 GMT
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Post by Deleted on Sept 19, 2013 11:16:49 GMT
Hi I would use a 105C rated capacitor at that location. These HAs often fail at just over 12 months due to heat related issues. Alex |
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Post by paradoxa on Sept 20, 2013 20:58:51 GMT
Thanks, i try to get a 105C.
Another thing, i changed the R13 and R14 to 5k adjustment pots, but when i set it to 13,5V i get noise after a while, i tried 2 different pots, any ideas ? :/
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Post by nandgate on Oct 17, 2013 1:07:00 GMT
I have Ian's amp running straight up to 50kHz instead of 10kHz (-0.5 dB) just by popping in IRL530 (not IRF510, the 530 has half the Vgs voltage so more headroom) and also replacing the LM317 for the higher grade LM317A. The IRF510 will do the trick too but the IRL530 will increase headroom/output power also and clean up the highs roll-off in a similar way. ;D Sorry if this is a stupid question but where are the FETs on the board. I'm having trouble telling their placement from the diagram. |
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Post by Deleted on Oct 17, 2013 1:30:41 GMT
Hi
Please refer to the photo on page 1 of this thread. They are clearly marked in the top left and right hand corners.
Alex
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Post by trismos on Nov 25, 2013 1:30:36 GMT
Hello
I have purchased the Bravo Audio Ocean Class A Tube Headphone amp (which I at first thought this thread was all about) and ordered a Psvane 12AU7-T for it before I found this forum. Some very knowledgeable people here and I doubt I will be performing many of the mods I have read about but fun to read nonetheless! I didn't read through all ten pages yet but has anyone used battery power with this unit? I have a (24v) Virtue M-901 running off a dual 12V -28AH battery psu so I have some available overhead.
Thx
Dave
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Post by arssonica on Nov 29, 2013 12:44:37 GMT
Hi at all. I'm new to the forum (this is my first post) and first of all I would say thank you to all the people that contributed to this great thread. I like music well reproduced, and I'm now approaching to the Headphone world. My first ampli was an X-can V1 lent to a friend. However, I wished to try an hybrid amplifier. I read all this post several times... and I'm sure I will read it again and again...  Reading all the genuine and enthusiastic reviews on this amazing HP amplifier, drove me to buy one Bravo V2 to mod. Before to proceed, I have some questions on topics that are not really clear to me. I'm not skilled on electronics, so I apologize if my questions could sound silly. Bias: I know it has to be set appropriately: could you help me what I have to do and where? Is there any guide that could help me (especially on this ampli)? Crosstalk mods (thanks oohms and solderdude): oohms in his first post suggest to cut some traces; one post after, solderdude tells about cutting the trace between pin 4&5. Should I do both mods? Documentation, pdf, previous posts: even if english is not my mothertongue, I feel that since the fist posts, people refer to other source of info. Also, going through the thread, I've found some documents from solderdude. Can you help me finding what I "miss/ed"? Last but no least is a little news: my Bravo V2 pcb seems to be a new version: I have only one ceramic cap (the one close to the power plug). There no cap close to the power switch. Thanks again at all for your help. Giuseppe |
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Post by chris1 on Dec 17, 2013 15:15:26 GMT
Ok, here goes, first post here and am early in the stages of learning electronics, but am enthusiastic and teachable. I picked up a couple bravo v2 amps recently and am inspired to mess with them. I have been into audio for some time and have dabbled quite a bit in speaker design, but never beyond that, i.e. never beyond caps, inductors, and resistors. Please be gentle on the noob  I'm trying to understand the purpose of each components function to help me understand the changes various mods make. Here are my first questions.. What is the function of the 2N3906 transistors in the V2? what would happen if they were not there? What is the function of the transistor circuit following the tube (the IRF630/LM317) and what would the effect be if it was not there (so just the output cap an resistor coming off the anode to the output. Sorry if this is a little rudimentary, but will help me understand the design better. Thanks! |
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Post by Deleted on Dec 17, 2013 23:14:17 GMT
Ok, here goes, first post here and am early in the stages of learning electronics, but am enthusiastic and teachable. I picked up a couple bravo v2 amps recently and am inspired to mess with them. I have been into audio for some time and have dabbled quite a bit in speaker design, but never beyond that, i.e. never beyond caps, inductors, and resistors. Please be gentle on the noob I'm trying to understand the purpose of each components function to help me understand the changes various mods make. Here are my first questions.. What is the function of the 2N3906 transistors in the V2? what would happen if they were not there? What is the function of the transistor circuit following the tube (the IRF630/LM317) and what would the effect be if it was not there (so just the output cap an resistor coming off the anode to the output. Sorry if this is a little rudimentary, but will help me understand the design better. Thanks! Chris VERY briefly, as I have an appointment shortly. The 2N3906 is a constant current source, and sets the anode current for the valve. The forward voltage drop of the Red LED is typically around 1.8V. The voltage drop across the base and emitter junction of the 2N3906 is a little over 600mV . Subtract that 600mV from 1.8V and that gives you the voltage drop across it's 3Kohm emitter resistor. This is then the anode current drawn by the valve. (I = E/R) The output impedance of the valve is very high, so the FET is used to provide a much lower impedance, and higher current to the headphones via the 1,000uF electrolytic capacitor. Alex |
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Post by chris1 on Dec 20, 2013 13:48:33 GMT
Thank you for that information, that helps me understand a lot more than before!
Chris
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Post by zasboy on Apr 1, 2014 22:09:17 GMT
Wanted to get my feet wet with tube amps and decided to pick up a Bravo Audio V2. Using a SuperLux HD 668B headphone, everything sounded much better. I'm not a very detailed audiophile but I noticed a good change and I liked it. I was curious if I can improve the sound qualities that with the modifications that people have done in this thread. So here are the list mods that I have done:
- Replaced both IRF630 with IRL510
- Replaced both LM317 with LM317AT
- Replaced both 2N3906 with BS170
- Replaced the big rear cap with Nichicon 4700uF/35V
- Replaced the two front caps with Nichicon 2200uF/35V
- Replaced 3K resistor with Bourns 5K trim pots(bias voltage adjustment)
- Shorted the two small caps under the volume pot(should have taken out the capacitors and jump it)
- Crosstalk mod
- Replaced 7.5 resistor with 8.8
- Soft start mod
- Replaced China tube with RCA 12au7 clear top(side getter)
Then I ran into a slight problem. I don't know where to measure the bias voltage. Looking at the tube socket from the bottom, I measure Pin 9 to Pin 4 and 5 and both are getting 7 volts. Adjusting the trim pot doesn't change the values.
Weird thing though, initially, the vocal was more on the right channel. Adjusting the pot, I got the vocal to be center.
Note: The tube was warm up for at least 30 minutes.
For now, the difference with the modification is amazing. Everything sounds more alive and I like it. But I do wish I can measure the bias voltage and set it correctly. I did search and couldn't find the answer. Any help would be great.
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Post by PinkFloyd on Apr 1, 2014 22:17:26 GMT
Wanted to get my feet wet with tube amps and decided to pick up a Bravo Audio V2. Using a SuperLux HD 668B headphone, everything sounded much better. I'm not a very detailed audiophile but I noticed a good change and I liked it. I was curious if I can improve the sound qualities that with the modifications that people have done in this thread. So here are the list mods that I have done: - Replaced both IRF630 with IRL510 - Replaced both LM317 with LM317AT - Replaced both 2N3906 with BS170 - Replaced the big rear cap with Nichicon 4700uF/35V - Replaced the two front caps with Nichicon 2200uF/35V - Replaced 3K resistor with Bourns 5K trim pots(bias voltage adjustment) - Shorted the two small caps under the volume pot(should have taken out the capacitors and jump it) - Crosstalk mod - Replaced 7.5 resistor with 8.8 - Soft start mod - Replaced China tube with RCA 12au7 clear top(side getter) Then I ran into a slight problem. I don't know where to measure the bias voltage. Looking at the tube socket from the bottom, I measure Pin 9 to Pin 4 and 5 and both are getting 7 volts. Adjusting the trim pot doesn't change the values. Weird thing though, initially, the vocal was more on the right channel. Adjusting the pot, I got the vocal to be center. Note: The tube was warm up for at least 30 minutes. For now, the difference with the modification is amazing. Everything sounds more alive and I like it. But I do wish I can measure the bias voltage and set it correctly. I did search and couldn't find the answer. Any help would be great. Hi Zasboy, Please check your private messages... I have given you the link to the world's expert on these amps. I am sure he will be more than happy to answer your questions. All the best, Mike. |
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Post by geemo4 on Jun 20, 2014 16:10:43 GMT
Thanks for this great thread - i will want to modify my V2 and just put the whole thread to an PDF. I may return with questions when i read it. I really appreciate this way people share their experiences.
Thanks a lot so far
PS: Does anybody know how to modify the Bravo V1 6922 (ECC88) to be able to use a 12AU7(ECC82) (Bravo V2) ? One user on page 1 wrote something that its possible - but can somebody say how ?
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Post by Deleted on Jun 21, 2014 1:01:07 GMT
Thanks for this great thread - i will want to modify my V2 and just put the whole thread to an PDF. I may return with questions when i read it. I really appreciate this way people share their experiences. Thanks a lot so far PS: Does anybody know how to modify the Bravo V1 6922 (ECC88) to be able to use a 12AU7(ECC82) (Bravo V2) ? One user on page 1 wrote something that its possible - but can somebody say how ? Hi This thread is fairly old now, and many of those HAs will by now have died a natural death from overheating problems, mainly due to poor layout Many die after just over 1 year of use. If it isn't covered in the long thread, it seems unlikely that you will be able to obtain further information in this area here. You may be able to extend it's life a little longer and possibly improve performance, by replacing the larger electrolytic capacitors which due to exposure to heat may be close to the end of their serviceable life. Alex
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Post by coolmeadowkid on Jul 19, 2014 23:05:45 GMT
In case this helps anyone, I built a wooden case for my Bravo V2 with an 80mm computer fan in the top blowing down on the amp, top plexi taken off, sides open to allow the air to escape. After 1.5 hours, my mosfet heat sinks are barely warm to the touch. I run the fan off a 12 volt wall wart. I think I'm going to wait for a while to do any of the mods...we'll see. I'm enjoying the sound I'm getting on my AKG K240s with an RCA clear top. Afraid I'll wreck the amp and be without for a while.  Thanks for all the posts here that have helped me with my decisions. Jim.<script charset="UTF-8" src="chrome://hdv/content/hdv.js" type="application/javascript"></script><script charset="UTF-8" src="chrome://hdv/content/hdv.js" type="application/javascript"></script> |
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Post by darkgenerals on Aug 6, 2014 16:32:54 GMT
I wanted to start off and say Hi, and thank you for this great resource.
I know this is a older thread and most guys have moved on to other things, but does any one happen to still have a copy of Solderdudes PDF mod list?
Thank you in advance, hopefully some one still has a copy.
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jc
Fully Modded
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Post by jc on Aug 6, 2014 18:42:14 GMT
Hello darkgenerals and welcome. You have a personal message.
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Post by coolmeadowkid on Aug 8, 2014 2:39:22 GMT
I'd appreciate a copy as well if you could point me to it. All the research I do comes up with different values or part numbers. Thanks! Jim
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Post by gr34td3str0y3r on Aug 8, 2014 15:41:45 GMT
sorry. don't hate me please. Just got my V2 (running q701) mega noob. First couple of mods you can suggest? I skimmed a few pages? (I already ordered some new tubes). Mosefests? Heat sinks?
The bass is SUPER muddy on some stuff. just sings on other stuff (really impressed). A bit of background hiss for sure (is this cross talk?)
Solderdudes PDF mod list sounds like a good place to start.
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