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Post by Deleted on May 16, 2011 6:06:46 GMT
There are 3 big capacitors. 1 in the back near the connectors and 2 somewhere on the board. Those 2 are the output capacitors.
the 220 Ohm (196 Ohm ?) resistors are underneath the 2 coupled heatsinks.
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Post by tacoboy on Jun 2, 2011 7:07:56 GMT
Those 220 Ohm are really hard to get at with the test leads, as they are each sandwiched between two heat-sinks, voltages were at just over 11, was able to adjust them to 14.88 and 14.90, that's good enough for now. Do they sell longer (the metal part) test leads for the DT-830B?
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Post by tomco on Jul 10, 2011 18:45:03 GMT
I used crocodile clips and sewing needles. Had a use a tempo sidekick though, don't know where I left my multimeter.
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Post by statix on May 27, 2012 0:36:07 GMT
Is the recommended bias voltage for these amps still 15.5 V? In the other stickied thread regarding the biasing and modding of the Indeed G2 amp, it appears that 12-13 V is recommended.
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Post by Deleted on May 28, 2012 8:20:06 GMT
12-13V is originally recommended / determined by ear (but NOT set) by Indeed. 15.5V (IRF) is determined by ear (Mike) and measurements (based on equal clipping properties, maximum output power and LM317 behavior).
You can set it to whatever value you prefer or thinks it sounds best to you. I encourage to simply experiment with both voltages and hear fo yourself.
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Post by proid on Jun 6, 2012 4:31:59 GMT
My Bravo v1 ( the 6922 version) has very noticeable noise, especially the left channel, it's so annoying, is there anyway to fix it?
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Post by Deleted on Jun 6, 2012 4:55:22 GMT
tube gone bad or with different tubes ?
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Post by proid on Jun 6, 2012 5:33:32 GMT
tube gone bad or with different tubes ? I switch tube to the G2 and it's sound fine, no noise so i think the problem is from the amp. My friend's V1 also has this problem.
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Post by Deleted on Jun 6, 2012 6:17:12 GMT
Does the problem reappear when you put the tube back in again ? It's not unknown for valve pins to become oxidised, and then respond to cleaning. Alex
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Post by proid on Jun 6, 2012 12:00:44 GMT
Does the problem reappear when you put the tube back in again ? It's not unknown for valve pins to become oxidised, and then respond to cleaning. Alex Problem still there since i first got it until now.
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Post by Deleted on Jun 6, 2012 12:14:01 GMT
There are a few posibilities.
1: These amps MIGHT have the same oscilation problem the Miridiy I once modded has, namely an oscillating LM317. This was cured by using an LM317A
2: you can increase the gate stopper resistor to 470 Ohm (from 220 Ohm) in case the IRF throws some oscillating in the mix.
3: You can replace the 2N..something with a low noise BC560
4: Since it is just one channel that is bad it seems unlikely it is the red LED so paralleling a 100uF cap might not help.
5: swap the MOSFET's and see if the problem changes channels (in that case replace the MOSFET's)
6: It is possible if you use highly sensitive headphones you are simply listening to the noise floor.
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Post by iol65 on Nov 19, 2012 10:44:12 GMT
Hi, Everybody! Sorry, for my English, that isn't my native. I've MUSE Class A Hybrid Tube Amplifier on 6N11 valve about one year. the schema is similar to this: 4.bp.blogspot.com/_ZKEQoUFwe3g/SbyPVvnL3LI/AAAAAAAABho/-9UPMdbN1nE/s1600-h/headhponeamp2.jpgSpec: Input Power: DC24V Input Sensitivity: 50mV Input Impedance: 100KOhm Output Impedance: 20~600 Ohm Gain: 20dB Frequency response: 10Hz-60KHz +/- 0.25dB Signal/Noise Ratio: >91dB Dynamic range: 84.6dBA(300 ohm) 89.8dBA(33 ohm) THD: 0.016%(300 ohm) 0.45%(33 ohm) IMD + Noise: 0.045(300 ohm) 0.42(33ohm) On last week the amp broke. It start to generate a noise, similar to working on low rotations tractor engine and then became silent. Symptoms: Red and blue LEDs not lights up. One of mosfets seriously overheats, the second one is warm. Anode voltage jumps(permanently changes) between 1v to 7v. Filter capacitor (6800µF 25v) was broken down. BTW, I tried to replace it and the new one broke too. Any suggestions or diagnostic methods? Thanks a lot.
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Post by buchwald53 on Feb 13, 2014 15:00:50 GMT
Hi. I tried it , voltimeter probe must have hit red LED, which went out, and now I have mono only. How to repair?
thanks,
Dan
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Post by Deleted on Feb 13, 2014 23:33:22 GMT
Hi. I tried it , voltimeter probe must have hit red LED, which went out, and now I have mono only. How to repair? thanks, Dan Dan A first step would be to replace the red LED, ensuring that it is the same way around, and hope that there isn't further damage. Alex
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Post by buchwald53 on Feb 14, 2014 15:59:37 GMT
thanks
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Post by cirric on Jun 23, 2015 15:55:33 GMT
Hi folks. I have two Bravo V3s, one the original which developed a hum in the left channel and then two, the replacement. Both are 6922EH equipped. Wrote the factory about the first and they said pretty much what you folks have said. Adjust the trim on the bias. I just now gotten the first unit hooked up to a VOM. I used the inboard resistor legs as test points. The voltages checked 21V (R)and 11V (L) approximately). The voltages do not seem to vary as I move the pots. There is still audible noise in the left channel. I have the caps 2200 gold and LRF510 FETs but I think I must get rid of the noise first. The Indeed 3 seems to be a more sturdy build with larger heat sinks etc. What to do, what to do...
Well PATIENCE is what to do! I found a position on the potentiometers where both voltages were within a small fraction of a volt. And just slightly over 12V. The noise is still there when turned down to almost off (or the volume of the signal is low). Hey, nothing is perfect right?
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Post by jim94536 on Dec 27, 2015 19:17:47 GMT
Hey Guys! Looking for a DAC that is about the same size as the Bravo V1. Hopefully with RCA in and RCA out. Any suggestions?
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jc
Fully Modded
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Post by jc on Dec 28, 2015 22:14:45 GMT
I really don't fancy your chances, most of that size are DAC & HP amp together. The only possibility that springs to mind is a Deltec (DPA) "Little Bit" or "PDM x" DAC obtained second hand. The Bravo is still smaller but would look quite neat sitting on top.
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