narayan
Audionut
I am a peaceful soul
Posts: 234
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Post by narayan on May 30, 2005 11:23:08 GMT 7
Here is another good one for discussion: If I have 2 amplifiers (RB03) which could be both used for bi-amping or can be switched to monoblocks, which would you guys suggest is the best configuration: 1. bi-amping (2 x 70 watts) for each channel, LF and HF. or 2. a pair of monoblocks (2 x 180 watts) for each speaker. nolan, have not tried bi amping LF and HF with my previous MF typhoon amps but i remember the british hifi press raving about the amp when bridged into monoblocks. it supposedly brought the amps into another level with the much higher power brought about by bridging. suggest you try both set ups at sound dimension
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Post by sandawa on Jun 29, 2005 20:15:18 GMT 7
Axel Dahl of The Vintage Knob, www.thevintageknob.org, has asked me to post photos of my Yamaha B3 and B4 power amps in Audio Karma, 204.10.140.18/forums/index.php?, in the meantime that he has yet to get a brochure of these models from Yamaha Japan for his website. I was thinking if Audio Karma members and TVK visitors get to see those photos, initially the B3, these should also appear here. B3 uses V-FETs (vertical field effect transistors) that were expensive to manufacture back in the '70s and eventually discontinued. The sound it produces is reportedly softer to the ears, and mimics the characteristics of valve amps (see The Vintage Knob website). V-FET driven amps are now collectors items for some audio enthusiasts in US and in Europe. Yamaha B3 is 70wpc bridgeable to 140 mono, 38 lbs., and 8X8X16 inches. A unit was auctioned last month in eBay Japan with an initial bid price of 29,000 yen. Here are some photos: top view front view with volume controls and power switch back view the connections, including L/R volume control and DC and bridge tied load (BTL) switches with the undercover removed, showing the huge transformers and two power caps
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Lordfoo
Audionut
Listen to be heard.
Posts: 225
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Post by Lordfoo on Nov 2, 2005 19:23:27 GMT 7
sir I have an Adcom Power amp The ADCOM GFA 585 Limited Edition
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Post by audioboy on Nov 4, 2005 7:34:05 GMT 7
lordfoo,
that amp is big!
should be a solution to power hungry speakers.
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narayan
Audionut
I am a peaceful soul
Posts: 234
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Post by narayan on Nov 4, 2005 9:36:59 GMT 7
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Post by sandawa on Nov 4, 2005 12:28:21 GMT 7
Adcom GFA585
Orion Bluebook says: 1.) 1990 model 2.)250wpc 3.) $1,200 brand new price 4.) $460 current resale price
Stereo Review 1994 has GFA5800 1.) 250wpc @ 8 ohms; 400wpc @ 4 ohms 2.) $1,600 brand new price 3.) 26kgs. total weight 4.) toroidal transformer and 100,000 microfarads of power caps 5.) uses Hexfets (hybrid Mosfets) 6.) with XLR balanced jacks
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Lordfoo
Audionut
Listen to be heard.
Posts: 225
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Post by Lordfoo on Nov 4, 2005 13:08:41 GMT 7
back pictures po. Its a pretty heavy amp. 50+ kilos yata. Right now i have problems with a humming sound that would most probably be due to dry capacitors. The capacitors are almost twice the size of coke in cans. (59,000 uf - 10 + 75% 75 VDC 95 surge.) When I turn off the amps. The music continuous for a while until the Capacitors are fully discharged. I am trying out 2nd hand caps from Raon. They might be dry. But i got them very cheaply. I am hopping they'd help me remove the caps as a possible source of the hum. If I am lucky the caps i got will work. I feel that these are dangerous amps to match with my speakers. They really blast out power thru the speakers.
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Lordfoo
Audionut
Listen to be heard.
Posts: 225
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Post by Lordfoo on Nov 4, 2005 13:09:19 GMT 7
Thanks for the info Sandawa, I found it difficult to find info on the GFA585LE. I understand that the GFA585 LE are two GFA565 monoblocks put together. It was supposed to be ADCOM's attempt to enter the audiophile market. back pictures po. The pre amp on top is an ADCOM GFT 500MKii preamp tuner. Its really a pretty heavy amp. 56+ lbs yata. Its a macho amp. Looks like 3sm car batteries. The power cords alone are quite thick. Right now i have problems with a humming sound that would most probably be due to dry capacitors. The capacitors are almost twice the size of coke in cans. (59,000 uf - 10 + 75% 75 VDC 95 surge.) See the caps i bought for 250 Pesos each, from a sidewalk vendor in Raon. When I turn off the amps, the music continuous for a while until the Capacitors are fully discharged. I am trying out 2nd hand caps from Raon. Its a risk that they are dry caps already but ... we'll see. I got them very cheaply. I am hopping they'd help me remove the caps as a possible source of the hum. If I am lucky the caps i got will work. I feel that these are dangerous amps to match with my speakers. They really blast out power thru the speakers and i fear for the speakers survival since the amp is not in tiptop condition.
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Post by <-94dB on Nov 13, 2005 8:31:04 GMT 7
lordfoo,
It's not a good idea to replace something that is not broken. The problem could be elsewhere. Try measuring the voltage across each power supply filer caps with a multimeter set to AC voltage measurement. Voltage should be 100mV AC or less with the amp in idle, i.e. no speaker connected and no input being applied. Dried up caps will show much higher AC across the two terminals.
Good luck!
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Post by sandawa on Nov 13, 2005 9:14:07 GMT 7
just to add. please be careful doing that, the last time i measured voltage on my Accuphase caps two months ago, i nearly got electrocuted.
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Lordfoo
Audionut
Listen to be heard.
Posts: 225
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Post by Lordfoo on Nov 14, 2005 15:48:10 GMT 7
Uh Oh!!! Two dire advises in a row!!!
One thing I do well is listen well... heheh.
I'm agonna ask for some technical help before I do something with my ADCOM then.
Salamat Po.
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Lordfoo
Audionut
Listen to be heard.
Posts: 225
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Post by Lordfoo on Nov 15, 2005 4:08:49 GMT 7
I also have another nice but problematic pre-amp/power amp combo that needs some fixin'. I'll take pics and post them after I get the power amp from storage with a Brod. Its a the Harman Kardon Citation Eleven and Twelve. The Pre amp works okay but the power amp sounds very garbled.
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Post by audiojunkie on May 28, 2007 17:34:27 GMT 7
: D Some pix of my amps ;D ;D B&K-TX4430 200watts x 3channel B&K-ST1400 105watts x 2channel
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Lordfoo
Audionut
Listen to be heard.
Posts: 225
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Post by Lordfoo on May 28, 2007 18:25:44 GMT 7
Sir ang linis tignan ng power amp mo ah.
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Post by audiojunkie on May 28, 2007 18:51:38 GMT 7
;D ;D Sir Bagong punas lang ;D ;D More pix external views: Front = Rear = Front with preamps:
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Post by akyatbundok on May 28, 2007 22:57:24 GMT 7
nice! some huge cans inside those amps.
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Post by audiojunkie on May 30, 2007 20:20:35 GMT 7
;D ;D ;D Those BIG cans will give you almost a minute of music after you switch of the power with signal still on. Swithing IC should wait about 5 mins before disconnecting, otherwise your apeaker or power output will blow.
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Post by suhian on Jun 28, 2014 13:49:34 GMT 7
Because Class A is simple and straightforward. No crossover distortions inherent in class B. But Class As are not powerful. And a real electricity eater, just around 20% efficient. For audiophiles who like comfortable listening levels in a typical room, 2 watts to 10 watts RMS are all that matters. Class A amps will do that perfectly. And they don't mind wasting electricity for what little they get. Agreed!. A power amp that has a class “A” design topology is usually single ended as 100% of the input signal is used (conduction angle Θ = 360°). The active element remains conducting all of the time as opposed to being push pull design such as the one in class AB topology. The advantage of class “A” are the following; 1.) Able to drive any load say all the way to 1 ohm impedance without any loss of power 2.) Because the device is never off, so there’s no turn on time, no problem with charge storage. 3.) They are better in high frequency performance and feedback loop stability. 4.) It usually operates with fewer high odd order harmonic, which is attributed to the sound being hard and harsh and higher even order harmonics that attributes to euphonic sound, which is very similar to tube power amplifier. The disadvantages are the following; 1.) As being mentioned already, they are very inefficient 2.) It’s very expensive to manufacture due to the requirements of large power supplies 3.) It runs very hot, so if you live in a hotter climate countries such as the Philippines, it will become problematic unless if you have a dedicated air conditioner system in your listening room 4.) The parts will worn out quite rapidly due to the heat being generated by its internal circuits, so therefore, it has to be recapped every 10 years or so, of course depending on the parts lifecycles. Pure Class “A” design topology power amps can be very powerful such as the ones that were designed and manufactured by companies such as Krell, Pass Labs, Mark Levinson, Classe’ (the earlier models) just to name a few, however, they cost an arm and a leg to own and maintain. Having said that, the Class AB design topology if it’s executed properly is the best compromise of all the power amp designs out there that are available today.
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Post by suhian on Jun 28, 2014 14:11:54 GMT 7
For the amp, it's still possible if they can totally eliminate gain slope for that region. Also, consider the frequency range of the whole chain from source to speaker, otherwise, the amp is useless having that frequency range. Sir avphile, i'm just wondering why some amplifiers (commonly to Tube amps) are rated 10hz - 60khz or higher than usual 20hz - 20khz? are this correct or attainable? Thanks? Not just the tube power amps, but the SS power amps can attained this frequency response also. As the matter of fact my SS power amp has a fundamental frequency response of <0.5 Hz to 120 kHz +0, –3 dB. I think it’s still harder to believe that the vinyl format has a usable frequency of 20 Hz-60 kHz.
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