Need advice on separates for vintage Polks

[falconcry72]

Hi guys,

I've been looking into separates for my 2 channel music rig. I'm new to separates. I'll be pushing RTA12C's, and hopefully some SDA's not TOO far down the line :)

I have a small budget (<500 total).

I have a local line on an Adcom GTP 500 pre, and an Adcom GFA 545 amp for $250 total.

It sounds like a good deal to me; what do you think?

How will this combo push my RTA12C's?
How will it push SDA's (probably 1C's or 2B's)?

Thanks guys, I think I just need some encouragement to pull the trigger ;)

[jimreeves]

Sounds like a good deal for the two pieces to me. Adcom gear is well thought of and if they're in good shape you should be able to get your investment back out of them if you need more power. From what I've read the 545 should give you the current capability your polks desire.

Best check with the seller if the amp is a 545 or a 545 II, different designs and one or the other may be non-common ground? I've never owned either so someone who knows should chime in here.

For SDA's you'll need a common ground amp, or a special SDA transformer interconnect. For your RTA12c's it won't matter.

Good luck!

Jim

[mhardy6647]

The early Monitor Series Polks liked Yamaha amplification (integrated, separates, and receivers), GAS power amps (e.g., Son of Ampzilla at 80 wpc), and also Luxman (receivers). The Adcoms (IMNSHO) will not be in the same league.

I've used a Yamaha CA-610II with Monitor 7As since 1978. Sounded good then and still does.

[falconcry72]

FYI the Adcom 545 is rated a 100 watts per channel whereas the Denon AVR I'm using now is 120 watts per channel, but I figure the Adcom separates will sound better. The Denon 3805 is a decent AVR though, so don't know how much of an improvement it will be. Whatdya think?

[jimreeves]

FYI the Adcom 545 is rated a 100 watts per channel whereas the Denon AVR I'm using now is 120 watts per channel, but I figure the Adcom separates will sound better. The Denon 3805 is a decent AVR though, so don't know how much of an improvement it will be. Whatdya think?

That was my first thought too, a sideways step in power output more or less. I'd guess that the 545 would have more current load capability than the Denon, and the polks tend to present a complex load to amplifiers. I think your assumption is probably correct, but a GFA 555 would be nicer!

[woodsman10b]

True reciever power is usually over-rated to say the least. True power amp power is usually under-rated and in most cases has much more current to drive power hungry speakers. The 545 would be a total upgrade in power compared to the avr.

[falconcry72]

True reciever power is usually over-rated to say the least. True power amp power is usually under-rated and in most cases has much more current to drive power hungry speakers. The 545 would be a total upgrade in power compared to the avr.

So does being a total upgrade in power translate to a total upgrade in sound quality? Like I said, I'm new to separates...:o

[comfortablycurt]

Take my word for it...the Adcom 545 will sound fantastic with those speakers! I'm running a 545 with both my Monitor 7A's and SDA 2A's...and it's yet to leave me disappointed.

The 545 won't drive them to levels quite as high as more powerful amps, but it can still easily drive my 2A's to 95db or so, and I rarely want to listen at levels higher than that. It's an excellent sounding little amp, and the 100 watts per channel would WALK ALL OVER the 120 watts from your AVR. There is no comparison between AVR watts and the wattage from a good dedicated power amp. It's about current, not wattage...and the Adcom is a high current design. Despite the 545 having "only" 100wpc, it has tons of dynamic headroom, and in dynamic peaks it's capable of putting out quite a bit more than it's rated 100 watts for quick dynamic bursts.

The Adcom GTP pre's aren't the greatest...but $250 for that combo is a GREAT deal. I paid $200 for just my 545...and I've never felt like I paid too much or anything like that. I'd snag that deal!

This combo will make an immense improvement over your AVR for 2 channel listening.

[Conradicles]

ADCOM sucks.









JK.


Nice deal and pick it up.

[falconcry72]

thanks for the encouragement fellas; I just have 2 hesitations:

1) I just dropped some money on a sweet vintage Polk deal I found on craigslist (there will be a post with pics in the vintage speakers section in about 30min) :)

2) I just remembered that the Denon is bi-ampable, so I could use some old AVR I have sittin around for home theatre cuz I don't care, and I could use the denon biamped for two channel, which would make 240 watts per channel, but that would only work with biampable speakers, of which I own none.

New questions:

1) Are all SDA's biampable or only some?

2) How would the denon's biamped 240 per channel compare to that same adcom combo?

thanks again; I couldn't spend all my money without your help :p

[comfortablycurt]

Only some of the SDA's are bi-ampable. I believe all of the TL's, and some of the SRS 2's. I'm not sure if any other ones were...I don't believe so.

Your Denon's "bi-amping" feature is a waste of time, and isn't even actually bi-amping. The power for all the channels on an AVR is derived from one common power block...not individual amps for all channels.

The power ratings for most AVR's are also very inaccurate. The 120 watt rating of your AVR is most likely with only one channel, or possibly 2 channels driven. However, this is the maximum output of the AVR's amplifier section.

Knowing that the power for all the channels is derived from one power block...it is impossible to double the power output by simply connecting two pairs of outputs. You'll still be driving the speakers with the exact same amount of power as you would be with a normal connection method.

The exact same power amp is still driving the exact same speakers. A more appropriate name for this method is "bi-wiring". There is a lot of debate as to whether that provides any improvements, but in my experience it doesn't.

If you've got the extra speaker wire laying around, it'd be worth trying, but I wouldn't anticipate any improvements.


Go for the Adcom separates. You'll be astonished at the difference it will make over your AVR.:)

[falconcry72]

Only some of the SDA's are bi-ampable. I believe all of the TL's, and some of the SRS 2's. I'm not sure if any other ones were...I don't believe so.

Your Denon's "bi-amping" feature is a waste of time, and isn't even actually bi-amping. The power for all the channels on an AVR is derived from one common power block...not individual amps for all channels.

The power ratings for most AVR's are also very inaccurate. The 120 watt rating of your AVR is most likely with only one channel, or possibly 2 channels driven. However, this is the maximum output of the AVR's amplifier section.

Knowing that the power for all the channels is derived from one power block...it is impossible to double the power output by simply connecting two pairs of outputs. You'll still be driving the speakers with the exact same amount of power as you would be with a normal connection method.

The exact same power amp is still driving the exact same speakers. A more appropriate name for this method is "bi-wiring". There is a lot of debate as to whether that provides any improvements, but in my experience it doesn't.

If you've got the extra speaker wire laying around, it'd be worth trying, but I wouldn't anticipate any improvements.


Go for the Adcom separates. You'll be astonished at the difference it will make over your AVR.:)

you're wrong about the denon. it has 7 separate amplifier sections at 120 each. the biamping abillity uses the normal 2 front sections as well as 2 that it "borrows' from the rear surrounds.

[Polkersince85]

There is still one power plug going to the wall outlet. Take the 120v watt rating at the power cord and divide by 2.5. Divide that by two and that will give you the watts per channel for two channel stereo. You can't pull power from the air.

[comfortablycurt]

you're wrong about the denon. it has 7 separate amplifier sections at 120 each. the biamping abillity uses the normal 2 front sections as well as 2 that it "borrows' from the rear surrounds.

So it has 7 separate mono-blocks, one for each channel? I'm not finding any mention of that anywhere. Not saying you're wrong...just trying to confirm one way or the other.



Either way...for 2 channel listening...a surround sound receiver is about the least ideal thing to use. There is a TON of unnecessary stuff in the signal path, and it all impacts the sound quality.

[falconcry72]

So it has 7 separate mono-blocks, one for each channel? I'm not finding any mention of that anywhere. Not saying you're wrong...just trying to confirm one way or the other.



Either way...for 2 channel listening...a surround sound receiver is about the least ideal thing to use. There is a TON of unnecessary stuff in the signal path, and it all impacts the sound quality.

i know that i need separates for my RTA12C's to really sing.

The denon that i have is good about trying to to be "pure" though. it has modes that turn off all video processing (including the front display) to let the active amplifying channels be the only working parts of the AVR.

here's a section of the manual:

Audio section
• Power amplifier
Rated output: Front: 120 W + 120 W (8 Ω/ohms, 20 Hz ~ 20 kHz with 0.05% T.H.D.)
160 W + 160 W (6 Ω/ohms, 1 kHz with 0.7% T.H.D.)
Center: 120 W (8 Ω/ohms, 20 Hz ~ 20 kHz with 0.05% T.H.D.)
160 W (6 Ω/ohms, 1 kHz with 0.7% T.H.D.)
Surround: 120 W + 120 W (8 Ω/ohms, 20 Hz ~ 20 kHz with 0.05% T.H.D.)
160 W + 160 W (6 Ω/ohms, 1 kHz with 0.7% T.H.D.)
Surround Back: 120 W + 120 W (8 Ω/ohms, 20 Hz ~ 20 kHz with 0.05% T.H.D.)
160 W + 160 W (6 Ω/ohms, 1 kHz with 0.7% T.H.D.)

i'm not sayin it's right, i'm just sayin it's written, and i would be glad to learn otherwise in this insatiable persuit. :)

[comfortablycurt]

That doesn't say anything about an all channels driven specification. Sometimes these power ratings are very unclear in their wording.

It sounds like it's rated at 120watts per channel with 2 channels driven, which would start going down after adding more channels into the mix. If that's the case, and the max output is 120 watts per channel, with 2 channels driven...the power output won't go up at all by connecting multiple outputs. You're still driving 2 channels, just with a bi-wiring method.

When driving 2 channels with 120 watts per channel, you are using your amps full power. Knowing that the power for all channels is coming from one common power block, it isn't possible for the power output to double by hooking up a second pair of outputs, since with 2 channels you're already tapping into all of the amps current.

Think of it as turning 120w x 2ch into 60w x 4ch. As I said above, a better name for it would be bi-wiring. There is much debate as to whether or not bi-wiring has any advantages. Many people are bi-wiring and have found great improvements, but I've never heard a difference personally.


This isn't the case with all AVR's. Some AVR's have separate monoblocks for each channel of amplification, rather than one common power amp for all channels. I'm not sure if that's the case with your Denon or not. I'm going to guess that it isn't, if anyone knows otherwise though, please correct me. Usually only really high end AVR's utilize separate monoblocks on every channel.



Point is, AVR power ratings are usually very inaccurate, and there isn't really a standard method by which they're all measured(at least not that I'm aware of). A lot of them are worded in ways that make it sound as if you actually are getting XXX wpc with all channels driven simultaneously, but in many cases, those ratings are actually with a single channel driven at a time.

[falconcry72]

That doesn't say anything about an all channels driven specification. It sounds like it's rated at 120watts per channel with 2 channels driven.

Sometimes these power ratings are very unclear in their wording.

dude, i like researched this AVR a good amount, and even though i cant upload the whole manual because it's, like, a bunch of MB's, i know that the 120 watts ratings are for every channel out of 7. that's why it was grounbreaking when it came out 5 years ago. BTW i'm a little drunk, ina good way :)

but seriously though, it's 120 x 7.

[falconcry72]

this is from cnet:

Product type: AV receiver
Amplifier total output power: 770 Watt

obviously 770 is smaller than 120 X 7, but you get the idea

[falconcry72]

There is still one power plug going to the wall outlet. Take the 120v watt rating at the power cord and divide by 2.5. Divide that by two and that will give you the watts per channel for two channel stereo. You can't pull power from the air.

ok, now I'm really confused. I'm a big time newb here... so are all power ratings just grossly inaccurate? Wouldn't the ratings for the Adcom with one plug be inaccurate also? Sorry for the ignorance, this is getting a little over my head:o

[Polkersince85]

The manual for your receiver states power consumption of 7.1 amps.

7.1 amps times 120 volts equals 852 watts total power consumption.

There will be some heat loss and requirements for other functions inside the receiver.

If everything went to the speakers, Take the 852w /2.5= 340w / 2ch =170wpc. The 125wpc @ 8 ohm (160wpc @ 6 ohm) rating will be about what you will get out of it regardless of how many speaker wires you hook up to it.

You would pull over 20 amps from the wall to get your 120wpc /all channels driven. It ain't gonna happen.
Receivers are not really efficient. If you want power, go with a separate amp.

[falconcry72]

The manual for your receiver states power consumption of 7.1 amps.

7.1 amps times 120 volts equals 852 watts total power consumption.

There will be some heat loss and requirements for other functions inside the receiver.

If everything went to the speakers, Take the 852w /2.5= 340w / 2ch =170wpc. The 125wpc @ 8 ohm (160wpc @ 6 ohm) rating will be about what you will get out of it regardless of how many speaker wires you hook up to it.

Receivers are not really efficient. If you want power, go with a separate amp.

Thanks for the help. So where does the "2.5" number that you divide by come from? I'm assuming it's a complex answer, of which I need the dumbed down version :)

[pitdogg2]

dude, i like researched this AVR a good amount, and even though i cant upload the whole manual because it's, like, a bunch of MB's, i know that the 120 watts ratings are for every channel out of 7. that's why it was grounbreaking when it came out 5 years ago. BTW i'm a little drunk, ina good way :)

but seriously though, it's 120 x 7.

I have the very same AVR when tested in the Home Theater mag it drove 2ch if i remember correctly at 160watts the all channels test it was down to 95 wpc still good but Curt is correct it still gets all the power for all the channels from one transformer. Although a very good product in my eye's it will never hold up to a separate 5-7 channels amp that is rated at the same power.
I must also add that the way of running a surround channel to a main channel to double the output by way of jumpers was frowned upon by Denon. This was done by lots of people but the AVR was never designed to do this and created much noise in the signal which is never good for the speakers. The 3808 was able to do this as it was designed for this by the Denon Engineers
Use the Denon's pre-outs and buy a good amp 2ch or 5ch and still get the good stuff from the Denon but get your cleaner better power from the better amps.

[falconcry72]

I have the very same AVR when tested in the Home Theater mag it drove 2ch if i remember correctly at 160watts the all channels test it was down to 95 wpc still good but Curt is correct it still gets all the power for all the channels from one transformer. Although a very good product in my eye's it will never hold up to a separate 5-7 channels amp that is rated at the same power.
I must also add that the way of running a surround channel to a main channel to double the output by way of jumpers was frowned upon by Denon. This was done by lots of people but the AVR was never designed to do this and created much noise in the signal which is never good for the speakers. The 3808 was able to do this as it was designed for this by the Denon Engineers
Use the Denon's pre-outs and buy a good amp 2ch or 5ch and still get the good stuff from the Denon but get your cleaner better power from the better amps.

Good call on using the Denon as a pre, that will allow me to afford a better power amp now, and then I can always upgrade to a different pre later. That makes me want to go bigger than the 545 though. hmm.