Thinking of adding 1985 adcom amp to onkyo 876. Good or bad idea? - AVS Forum
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post #1 of 16 Old 03-18-2013, 07:19 AM - Thread Starter
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I have a 200 watt 2 channel adcom gfa555 amp that i purchased in 1985 that has been sitting in the closet. I have an onkyo 876 receiver that is hooked up to 7.1 aperion intimus speakers. The onkyo sounds great on movies and blu ray concerts however on 2 channel cd the sound is lacking. Would adding the adcom amp to power the front left/right speakers improve the sound in two channel and surround sound formats or am i better off just not bothering? Would i need to recalibrate the audyssey and would the surround sound on movies sound suffer because of different amps driving different front speakers? Any opinions or similar experience and thoughts would be appreciated.
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post #2 of 16 Old 03-18-2013, 12:59 PM
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First I'd want to make sure that the Adcom is in good operating condition, was it in a box to prevent it being a dust collector? Are all the capacitors in good shape? 28 years is a long time...

More likely simply the difference in recordings that sounds different to you, but you don't specify how you're listening to the 2ch cd--stereo mode or in multi-channel or? The more powerful amp may help you get slightly higher spl or provide a tad more headroom but that's a fairly powerful amp in that avr already (and it takes about a doubling of power just to increase spl by 3dB), An amp shouldn't color the sound, just amplify the signal. If you add the amp, you're still using the pre-amp portion of your avr and the sound should be the same within specs. Re-run Audyssey. I use outboard amps (Carver M500t's for my L/C/R speakers) with my Onkyo AVR's amps handling the other 4 channels just for a bit less work for the avr's amp as well as a bit more power (my Onkyo is less powerful than yours, too, and my front speakers don't have a very high sensitivity).

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post #3 of 16 Old 03-18-2013, 03:43 PM
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Worth a try to see how it sounds. Bring the adcom up slowly over a few hours to break the caps in slowly. Before you plugin the speakers check the output terminals with the amp on with a volt meter, it should be less than 50mV.

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post #4 of 16 Old 03-18-2013, 06:27 PM - Thread Starter
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I went ahead and hooked it up and blasted it for several hours. My initial impression was Wow!!! Although someone had mentioned it shouldnt sound different i noticed the bass was much deeper and the highs werent as high/Bright. I tried both two channel stereo cd's and dolby dts-hd with blu ray concerts and movies. The biggest difference was the bass And of course It played much louder!! i left audyssey off and will play with it some more but overall im really impressed with the change and a i am going to leave it so ill have 200 watts per channel for the l/r speakers and 140 watts (per two channel) for the remaining 5 speakers. I also found this article from cnet on old audio equipment which i found interesting...


http://news.cnet.com/8301-13645_3-20082026-47/how-can-30-year-old-receivers-sound-better-than-new-ones/
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post #5 of 16 Old 03-18-2013, 07:34 PM - Thread Starter
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Interesting.... I read the link in the cnet article after i had posted my comments and they made they same observations in sound quality with the bass being the biggest difference.

Aso when i bought the adcom amp in 1985 i had it hooked up to a nad preamp and top of the line polk sda-srs speakers. I remember when i auditioned the equipment the polk sounded better with the adcom compared to the other amps i heard using the same nad preamp ( im pretty sure one of the amps was a carver) so i do believe amps can make a difference in sound quality and not just loudness.
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post #6 of 16 Old 03-18-2013, 08:07 PM
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Quote:
Originally Posted by Mr2Spyder View Post

Interesting.... I read the link in the cnet article after i had posted my comments and they made they same observations in sound quality with the bass being the biggest difference.

Aso when i bought the adcom amp in 1985 i had it hooked up to a nad preamp and top of the line polk sda-srs speakers. I remember when i auditioned the equipment the polk sounded better with the adcom compared to the other amps i heard using the same nad preamp ( im pretty sure one of the amps was a carver) so i do believe amps can make a difference in sound quality and not just loudness.

You're sure the gain structure is equivalent? Did you level match? Did you rerun Audyssey?

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post #7 of 16 Old 03-18-2013, 09:22 PM - Thread Starter
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Oops
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post #8 of 16 Old 03-18-2013, 09:23 PM - Thread Starter
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Originally Posted by lovinthehd View Post

You're sure the gain structure is equivalent? Did you level match? Did you rerun Audyssey?


No i havent rereun audyssey or level matched yet but will do it. Most of my initial listening was with cd's played through 2 channel stereo "pure audio" mode which sounded great however when i ran dts-hd movies i noticed the center didnt seem to blend in as well with the left/right speakers so i'll need to tweak it. Ill get a better idea how they sound after tweaking it and extended listening at a more reasonable volume level . Thanks for the advice.

Also does anyone know since my onkyo is no longer powering the left and right speakers does that free up or provide more power to the other speakers and will the onkyo run cooler?
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post #9 of 16 Old 03-19-2013, 08:30 PM - Thread Starter
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[After doing some research on aging capaciters and the fact that the amp is 28 years old and had not been turned on for at least 8 years ive decided to not use the amp. I listend to it for about 30 minutes and then switched back to the receivers amp and have to say i still prefered the sound of the adcom. Im just worried because the amp is so old it might eventually fry my equipment. Im thinking of getting an outlaw or emotiva amp in the future.
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post #10 of 16 Old 03-19-2013, 09:49 PM
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Quote:
Originally Posted by Mr2Spyder View Post

Quote:
Originally Posted by lovinthehd View Post

You're sure the gain structure is equivalent? Did you level match? Did you rerun Audyssey?


No i havent rereun audyssey or level matched yet but will do it. Most of my initial listening was with cd's played through 2 channel stereo "pure audio" mode which sounded great however when i ran dts-hd movies i noticed the center didnt seem to blend in as well with the left/right speakers so i'll need to tweak it. Ill get a better idea how they sound after tweaking it and extended listening at a more reasonable volume level . Thanks for the advice.

Also does anyone know since my onkyo is no longer powering the left and right speakers does that free up or provide more power to the other speakers and will the onkyo run cooler?

Yes, less burden on your Onkyo amp by supplementing it with an external amp...

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post #11 of 16 Old 03-20-2013, 04:58 AM
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Quote:
Originally Posted by Mr2Spyder View Post

[After doing some research on aging capaciters and the fact that the amp is 28 years old and had not been turned on for at least 8 years ive decided to not use the amp. I listend to it for about 30 minutes and then switched back to the receivers amp and have to say i still prefered the sound of the adcom. Im just worried because the amp is so old it might eventually fry my equipment. Im thinking of getting an outlaw or emotiva amp in the future.

Fry what? Amps are the longest running and most dependable pieces among the typical audio gear we use. Just because they haven't been turned on [provided they been kept in optimal storage condition] they won't pose any harm to the rest of the gear, and probably will outlive many of it. As it mentioned every time there is a new piece in the chain, it's wise to rerun any Room correction software, mostly for precise level balance then anything else. I would use the Adcom, and if you need more outboard amp channels, buy one to reproduce those channels, say a 3 or a 5 ch one. You can always use the Adcom to power the surrounds for instance, if you feel you need an amp to run all of the front channels, or if you have a 7.1 set up you can just use for the back surrounds etc... the possibilities are numerous.

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post #12 of 16 Old 03-20-2013, 11:41 AM
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I would not hesitate to use the ADCOM, that amp could run forever with no problems.

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post #13 of 16 Old 03-21-2013, 12:08 PM - Thread Starter
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Thanks for the advice but all this talk about dried up and leaky capacitors has me worried. The amp sounded good however it is 28 years old. After some research I've decided to pull the trigger on the Emotiva XPA-5!!! 200wx 5 of power all channels driven so ill have even distribution of power to the fronts and surrounds and will let the Onkyo power the rears. This will allow me to purchase a surround sound preamp in the future and I can use the Onkyo in another room. Ive caught the audio upgrade bug...smile.gif
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post #14 of 16 Old 03-21-2013, 12:47 PM
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Originally Posted by Mr2Spyder View Post

Thanks for the advice but all this talk about dried up and leaky capacitors has me worried. The amp sounded good however it is 28 years old. After some research I've decided to pull the trigger on the Emotiva XPA-5!!! 200wx 5 of power all channels driven so ill have even distribution of power to the fronts and surrounds and will let the Onkyo power the rears. This will allow me to purchase a surround sound preamp in the future and I can use the Onkyo in another room. Ive caught the audio upgrade bug...smile.gif

You can visually inspect the caps before you give up on the Adcom long term...or have an electronics guy check it out.

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post #15 of 16 Old 03-21-2013, 01:34 PM - Thread Starter
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You can visually inspect the caps before you give up on the Adcom long term...or have an electronics guy check it out.

I'm not paying anyone to take a look at it but I might perform a visual inspection of the caps. What do they look like and what should I be looking for to tell if they are damaged? Any risk in removing the cover? I've left the adcom unplugged for at least 24hours but I dont knot know if amps still hold a charge after unplugging from a wall outlet. I I have an Onkyo 605 in another room that has a zone 2 l/r pre out so I think I can hook up the adcom amp to it and run a second pair of speakers.
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post #16 of 16 Old 03-21-2013, 07:16 PM
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Enjoy your amp, it is a good one, it should work just fine, don't worry about it as long as you don't turn it up ear splitting high. It sounds like it works just fine.

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