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Post by hifijunkie on Jul 7, 2009 6:16:00 GMT
Hello guys,
I have this chinese amp Bada DC222 rated at 95W . It sound very good and i really like it. The problem is that the voltage rating is 220V and here in India, sometimes the voltage drops to 170V and whenever it happens, the woofers produce a deep humm sound.
Is there any solution to this problem apart from buying a voltage conditioner ??
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Deleted
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Post by Deleted on Jul 7, 2009 6:23:13 GMT
Hello guys, I have this chinese amp Bada DC222 rated at 95W . It sound very good and i really like it. The problem is that the voltage rating is 220V and here in India, sometimes the voltage drops to 170V and whenever it happens, the woofers produce a deep humm sound. Is there any solution to this problem apart from buying a voltage conditioner ?? hifijunkie I think you have answered your own question.It would be very difficult to make it work over a very wide voltage range. It could be possible if the voltage was consistently lower, but not so easy if it varies over a wide range. SandyK |
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Post by hifijunkie on Jul 7, 2009 6:49:25 GMT
Voltage conditioner is an expensive option to me !! I am not too conversant with electronics stuff ... was hoping about any DIY solution for this .....Maybe a DIY circuit boards, if it does the job  |
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Post by Deleted on Jul 7, 2009 6:59:36 GMT
Voltage conditioner is an expensive option to me !! I am not too conversant with electronics stuff ... was hoping about any DIY solution for this .....Maybe a DIY circuit boards, if it does the job hifijunkie Perhaps Robert can come up with some other suggestion, but I can't see any inexpensive answer to your problem. Switch Mode Power supplies can work over very wide voltage ranges, but linear power supplies, which your amplifier almost certainly has, can not. SandyK |
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Will
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Post by Will on Jul 7, 2009 8:15:21 GMT
I think a DIY solution maybe difficult.
Switch mode PSU maybe good solution, but have you considered a basic Uniterruptible Power Supply (UPS)? You certainly do not want to be running your equipment in brown-out conditions, and a basic UPS would give an alarm when the voltage drops, giving you chance to turn off the equipment before Vout of the UPS becomes a problem. I dont know what prices are like in India, but you can get a simple UPS for about £55.
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Post by hifijunkie on Jul 7, 2009 11:44:23 GMT
I have a computer SMPS lying around somewhere .... it is rated at 400W , can that be used ? Obviously it needs to be modded quite a bit
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Post by Deleted on Jul 7, 2009 12:02:50 GMT
I have a computer SMPS lying around somewhere .... it is rated at 400W , can that be used ? Obviously it needs to be modded quite a bit hifijunkie No, that can't be used ! You need to be VERY experienced to play around with modifying one of those. Those things can kill you !!! Don't even think about playing around with one of those,or Microwave ovens.They are potential death traps. SandyK |
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rickcr42
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Post by rickcr42 on Jul 7, 2009 12:41:14 GMT
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Post by Deleted on Jul 7, 2009 17:35:23 GMT
I have the same proble in Spain, though the lowest I've measured was about 180v. My CDP suffers hum 'cos of this, I tried the UPS for my old desktop which greatly reduced the problem, it's now rare to hear the hum through the 'speakers.
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Post by Deleted on Jul 7, 2009 22:40:26 GMT
The information that Rick has posted is a well proven design that will give a modest increase in mains voltage. However, I doubt that with the example shown, that increasing mains voltage from 170 to 176, will eradicate the problem. If you are tempted to give,for example, a 30V boost to take the voltage up to 200VAC, and the mains voltage returns to normal after peak demand, and you do not notice this, and remove the boost, then the extra 30VAC may cause severe damage to your amplifier. Aside from that, is the added cost of the transformers,case and other components.You would also need to be very careful with the wiring of the unit, as 200VAC is more than capable of killing you, if due care is not taken. SandyK P.S. IF your mains voltage is ALWAYS low, then this kind of circuit may be very worthwhile in the hands of more experienced constructors. As an aside, if your mains voltage drops this low, it may be a wise precaution to turn off Refrigerators, washing machines etc. until the mains voltage rises again. These kind of motors may burn out under "brownout" conditions. |
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Post by hifijunkie on Jul 8, 2009 7:03:41 GMT
The typical components that are going to be used in my home are :
1 amp - 350W
1 CDP - 60W
1 EHP 606 - 50W
1 HTiB - 150W
1 LCD - 75W
In future i may add a tuner and a DAC
The total wattage as of now is 685 W. Based on this can you guys estimate how many amps is needed in the voltage stabilizer ?? Would a 3 amp suffice or a 6 amp model is needed ?
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Post by Deleted on Jul 8, 2009 7:13:29 GMT
The typical components that are going to be used in my home are : 1 amp - 350W 1 CDP - 60W 1 EHP 606 - 50W 1 HTiB - 150W 1 LCDitor - 75W In future i may add a tuner and a DAC The total wattage as of now is 685 W. Based on this can you guys estimate how many amps is needed in the voltage stabilizer ?? Would a 3 amp suffice or a 6 amp model is needed ? hifijunkie A 3A model could be cutting it a little close, even though they won't all be in use at the same time. SandyK |
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rickcr42
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Post by rickcr42 on Jul 8, 2009 12:08:04 GMT
Exactly,why I said "modified to your application".
I think maybe "Step A" would be to either purchase or build a line quality monitor so you can log the times when the 50VAC sag takes effect and maybe try and listen during other times but if this is a random thing with no pattern then you are pretty much stuck with a permanant fix path.
BTW-I also beleive you are "off" on your analisis of the why the sound degrades here because a lower voltage for the B+ will NOT cause the problems you describe but lower TUBE HEATER voltages can and will because if you look at ANY tube data sheet the only CONSTANT are the heater requirements while the plate curves will show you a WIDE RANGE of operating possibles and why you see the same tubes in gear having widely different B+ voltages and still sound fine
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rickcr42
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Post by rickcr42 on Jul 8, 2009 13:02:47 GMT
Giving this a bit of thought.................always a dangerous proposition 'cause I have just enough knowledge to be frikkin' dangerous................I'm thinking the "fix" may not be all that complicated.Pain in the ass but not complicated 1-You need some means of monitoring your heater supply voltage all the time which means you will likely need to find a place on the amp chassis where you can mount a pair of test points (mini test points,banana plug jacks,binding post pair,etc.) to which you will attach leads to your heater supply and in turn an accurate voltage meter.This meter needs to be one that itself will not "sag" the voltage by having too high a current draw but it would be a RARE voltage meter that has even miniscule current draw 2-Build a diode "voltage doubler" into your heater supply followed by a varaible "resistor reducer" so you can dial in the correct voltages of your heater (don't know the tubes involved both will either be 6.3V or 12.6V so 6/12 will work fine) www.diyforums.org/MAX/MAXheaterResistor.phpor something like this (modified,like lose the led and pre-voltage divider tap)  At worst if you are "lax" in watching the meter and the voltage goes high you will shorten the life of the tubes in the "over" voltage side of things if you are lax in the monitoring and your SQ will suffer in the "under" voltage conditions if you fail to adjust up but seems to be a simple solution,one costing not a lot more than TIME TO IMPLEMENT AND USE,to a really not so very complicated problem unless i am missing something here (it happens  ) hope this at least gets your problem solving side of the brain into fifth gear  |
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Post by Deleted on Jul 8, 2009 21:35:37 GMT
As this is a Hybrid design, there is also the likelyhood of any onboard voltage regulators having insufficient IN/OUT voltage difference to stay in regulation.
"The preamp section starts with a low noise R-Core transformer and feeds 4 12AU7
tubes for a warm, detailed sound. The solid state section is fed by a torodial
transformer that feeds up to 8 Toshiba output MOSFET transistors. Wina, Solen
capacitors throughout the preamp and main amplification circuits. The amplifier
produces 95 watts per channel into 8 ohms and doubles it (190 watts) into 4 ohms for a
clear detailed sound.
more... Features
Specifications
Maximum output power 95W+95W (8 @ohms)
190W+190W (4 @ ohms)
Frequency response : 20Hz~20kHz (+1.5dB)
Harmonics distortion : <0.5% (1kHz 10W)
Signal to noise ratio > 85dB
Power Requirements : ~110V 60Hz
Power Consumption: =350W
Uses 4 12AU7 Tubes in Preamp Section
Details
Hybrid amp with 4 12AU7 tubes in the
preamp section and MOSFETS in the
output section. 4 inputs, gold plated RCA
jacks, gold plated speaker jacks, record
out, muting circuit, warm up circuit, record
out, isolated power dual power supplies
and thick aluminum chassis. The Bada
DC-222 comes with user guide, power
cord and ships from Chicago, IL
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Jul 9, 2009 15:45:46 GMT
did not realize that me having a real prejudice against the "Badda" from past experience with a cat at Head-Fi who would manage to squeeze in a recommendation for even if the thread had NOTHING to do with the amp or hell,amps in general which led the mods to trying to decipher the purpose with "Behind the scenes MOT" being the consensus at the time though up 'til i left no real proof of so even seeing the WORD makes my eyes glaze over and no,i don't do any "this is what it is and does" type research which is 100% true but at the same time 100% meaningless unless the voltage falls so low the solid state devices are below the limits of their operating point range. for instance.I run my Szekeres Amp at +24VDC,a voltage which for me has transcended the design to a level that +12VDC could not reach yet most builders are quite happy with the lower voltage spec because when you choose the voltage you also choose the size of the source resistor to set idle current according to Ohms Law for ideal operation but higher or lower ? Still works,just not optimal. My DITB (DAC In The Box) came stock with a bipolar 12VDC "Power Station" for the raw DC feed and internal +/-5VDC regulation for each stage including the analog section which uses an OP275 for the filter and drive.changing this to an external +/-15VDC "Raw" and the analog section V-Regs to +/-12VDC has increaded the performance level immensely but does that mean it was unlistenable before the "increased voltage" mod ? Many who have the stock DAC say otherwise so voltage levels DO have an effect but are usually not a make or break unless out of the usable range of the amplifying device If I understand the Badda the hybrid nature is VT front end mated to a SS output "current pump" stage similiar to the Melos so in reality has no actual NEED for voltage regulation much like it is rare to see voltage regulation in any power amp past the front end and driver sections and they work just fine as decades of designs prove out so while you would have a lower idle current at turn on with a reduced voltage you would NOT be inducing hum there being no mechanism to cause it under this circumstance Where this could possibly change is if there is an active current source loading either the tubes OR the output stage because this part will go totally off spec outside of a very narrowly defined range of voltages making the "fix" either get the mains voltage stabilized or diconnect the CCS totally and replace with a passive resistor which has far less dependance on a stabilized voltage even though it too will chage in current delivered to load depending on voltage (again a simple ohms law equation) Bottom line is-the more "complicated" a circuit the more it needs to be pampered unlike a simple circuit which will mostly just vary in ultimate voltage output delivery and possibly distortion levels which will be higher but still tolerable in level if the voltage should go low and maybe why I just about never use voltage regulation (at least any series regulator and rarely shunt regs these days) with op-amp based circuits which I feel add more SQ problems (with the series regs noise increase with super regulators and more often than not bandwidth limitations,especially in these days of using super fast high bandwidth op-amps mated to a LOW BANDWIDTH three terminal V-Reg which totally blows the PSU/Circuit 2:1 (minimum !) ratio all to hell because the regs just can't get there ) than fix any part specific problems since the PSSR of these parts already being high means fairly immune to PSU problems other than ripple and/or rectifier noise which is easily addressed with snubbers and a multiple stage "Pi" filter. With tubes ? "Starved Mode" is a condition that usually results in the classic "tube sound",something the Tube Audio Ignorant actually find to be a good thing (I want to warm up my CD player  ) but is a thing that will do no actual harm other than change the sonic character of the gear from clean to fat and romantic,something one can live with for short duration periods if that is the only option in an area where the mains voltage strays so from from the standard but the heater voltage is something i would personally have to address and make right and the above combined with some kind of voltage monitoring/automatic voltage step increase is a thing i would spend sleepless nights designing....just me bro |
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rickcr42
Fully Modded
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Post by rickcr42 on Jul 10, 2009 10:48:50 GMT
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)
) but is a thing that will do no actual harm other than change the sonic character of the gear from clean to fat and romantic,something one can live with for short duration periods if that is the only option in an area where the mains voltage strays so from from the standard but the heater voltage is something i would personally have to address and make right and the above combined with some kind of voltage monitoring/automatic voltage step increase is a thing i would spend sleepless nights designing....just me bro