5-channel HT with higher power amplification levels for only front channels

[robertbartsch]

I've owned many many receivers over the years and, in general, I'm not impressed with their sound quality. Yeah, that would be the whole bunch...

Currently, I have a 5.1-channel Oynko with 140 WPC and a few Denon 5.1 receivers, 1 Denon receiver has 105 WPC. The sound quality of the Oynko just plane stinks and really loud levels can't be achieved - ever. I think the published Oynko receiver power ratings are very suspect or their maybe the pre-amp is not designed to drive the power amps very loud. The sound quality of the Denon receivers is OK, but, in general, the power levels are not sufficient for my installations.

With a couple of minor acceptions, my speakers in all installations in the house and garage are typically JBL 2225, 2425, 2405. I love the sound quality at both low and high levels and they are reasonably efficient and, generally, they can take some abuse with ease. I also have several sub-powered 18" JBL speakers, which are really great.

In one TV room experiment about 3 years ago, I connected only two JBL speakers to the Oynko and because the sound was so disappointing, I connected the Oynko pre-amp outputs to an Adcom 555 power amplifier with 200WPC. As time went on, I added two rear speakers and a center speaker, a couple of powered sub-woofers and these newer additions for the rear and center channels were driven only off the Oynko receiver. Several years ago, the Adcom power amp was moved to perform different service in another system and currently, all the that systems 5 speakers are driven from the Oynko receiver only.

My experience with 5 channel systems is that they are annoying to balance the volume levels, especially when non-music sources sound better on stereo only and having to switch to multi-channel system and to re-balance for music material over and over again. I assume this is another disadvantage for using only one external power amplifier.

I'm currently weighing the idea of buying a few used Adcom 555 power amplifiers for the rear channels of two systems.

Questions
1. Is it common to connect only the two front channels of a 5.1 system receiver to an external power amplifier? My recollection is that the sound is not too bad???
2. If I decided to go with all external power amps that are connected to the receiver pre-amp outputs, is it better to go with multi-channel power amps or two or three stereo power amplifiers?
3. Are there any alternatives for receiver powered ONLY systems like the Denon 5700 receiver at 140WPS? These receivers are cheap as dirt on E-bay now.
4. Are the HDMI outputs and the newer THX decoders that are on new 2016 receivers so useful when used with a satellite cable source (ATT Satelite)?

SORRY FOR THE LONG POST...

[Ed Zeppeli]

I can't answer all your questions but I use a Marantz SR7008 and utilize the pre-outs to drive a Crown and my 4430 mains. Their room eq system seems to do a pretty good job of balancing speaker levels but I always tend to bump up the centre channel output for movie dialogue. I always play music in two channel mode.

To me, it seems unnecessary to have external amps for surround data as I've never heard any deficiencies there and the internal amps of the receiver seem adequate.

I am curious as to why you feel you're always re-balancing your system. Is it a mixing issue or an output issue?


Best Regards,

Warren

[Chris Brown]

There is nothing wrong with using an external amp just for your front speakers. How much this benefits you depends a lot on how your receiver is designed, and how you have your speakers configured.

My home theater receiver for example, has a shared power supply. It will do over 200wpc (8ohms, 20hz-20khz, 1% THD) with only 2 channels driven, but falls to less than 100wpc (8ohms, 20hz-20khz, 1% THD) with all 7 channels driven simultaneously. So in my case, the more channels I can offload to external amplifiers, the more power the built-in amplifier can direct to the remaining channels.

Speaker configuration matters also. Low-frequency content is what consumes the most power. Most have their surround speakers set to "small", and with a THX spec crossover that means anything under 80hz is being sent to the subwoofer (and any speakers that are set to "large"). My receiver for example, jumps up to ~150wpc with all 7 channels driven when measured at 1khz instead of 20hz-20khz. If you only have two speakers that are set to "large", then you probably don't need dedicated amplifiers for anything else. If you are running "large" speakers on all channels, then you might benefit from more than one external amplifier.

[robertbartsch]

Cable box is used for news (2 channel stereo only) and for music (all channel stereo). I found I'm re-balancing the speakers often after I change modes.

**********

I moved to a home that is only 9 years old about 3 years ago. ALL THE CIRCUITS IN THE FUSE BOX ARE 10 AMP!

I'm researching BIG milti-channel amplifiers and I think 10 amp circuits are not going to work. Is that correct?

[Ed Zeppeli]

Cable box is used for news (2 channel stereo only) and for music (all channel stereo). I found I'm re-balancing the speakers often after I change modes.

**********

I moved to a home that is only 9 years old about 3 years ago. ALL THE CIRCUITS IN THE FUSE BOX ARE 10 AMP!

I'm researching BIG milti-channel amplifiers and I think 10 amp circuits are not going to work. Is that correct?

Wow. 10 amp breakers seems....not to code. You can't even run a toaster or blowdryer with that!

[1audiohack]

....I moved to a home that is only 9 years old about 3 years ago. ALL THE CIRCUITS IN THE FUSE BOX ARE 10 AMP!

Can't be.

The breaker amp rating is on the toggle. Newer breakers have the kA rating in white or yellow on the body. This is usually 10kA and what many people see first. It used to be this was just in raised black fine print.

Look again. :)

Barry.

[Mr. Widget]

I've owned many many receivers over the years and, in general, I'm not impressed with their sound quality. Yeah, that would be the whole bunch...Agreed 100%

I have personally used, sold, and installed Marantz, Denon, Onkyo, Integra, and most of the other AVRs at one point or another and have never felt any of them brought out the potential of the speakers... But unless you're going to spend ungodly sums of money I think using one of these AVR's with upgraded amplification on the front channels is the best way to go.



I am curious as to why you feel you're always re-balancing your system. Is it a mixing issue or an output issue?
+1

Using external amps will not affect this... Once the system is initially balanced.




To me, it seems unnecessary to have external amps for surround data as I've never heard any deficiencies there and the internal amps of the receiver seem adequate.
Agreed. I've used the built in AVR's amps for surrounds in numerous systems as a cost savings measure. I'm sure using external higher-quality amplifiers for all channels will be superior… But perhaps not particularly audible in the surrounds.


Widget

[rdgrimes]

Even the biggest flagship AVRs are mediocre even for 2-ch power. For 5.1 music they are useless at volume.
I'm recommending the Outlaw 2200 mono-block, you can buy as many as you want. Most bigger AVRs can handle running surround channels only, but L-R and Center really benefit from a real amp.

[Mr. Widget]

Even the biggest flagship AVRs are mediocre even for 2-ch power. For 5.1 music they are useless at volume. In my earlier post I wasn't commenting on maximum SPL but rather sound quality in general, but it wouldn't surprise me if maximum SPL was also compromised.

Other than the added features that most people do not need, I see no benefit in buying the more expensive AVRs. I always spec the least expensive model with line level outputs and whatever other features that are needed to satisfy the system design.



Widget

[Ed Zeppeli]

Other than the added features that most people do not need, I see no benefit in buying the more expensive AVRs. I always spec the least expensive model with line level outputs and whatever other features that are needed to satisfy the system design.



Widget

Good call. I always seek out the receivers with pre outs as well. Unfortunately that feature seems to only be common on the more expensive models. The main reason I bought the Marantz was for the pre outs as well as the decent room eq function of Audyssey XT. Also, they were clearing them out at over 50% off.

Seeking out a really nice pre-amp that would serve those functions would likely have cost multiple times more $.

[robertbartsch]

Our house, a 3,300SF ranch, was built new in 2006 and it sat empty for 7 years until we bought it. It has 33 circuits in the breaker box and ALL are marked 10KA on the circuit breakers - including the 2 circuits that are 240 volts (oven and A/C).

We have an empty 380SF room upstairs that is unfinished. Since no empty circuits slots are left in the smallish breaker box, I called a licensed electrician out to look at putting an extra box in for the new bathroom we wish to add. The only time we have had issues with blown breakers is for the outdoor circuit which was running an 800 watt electric smoker.

I'm reading on the Internet about people who are blowing 20 amp breakers using larger multi-channel power amplifiers.

[Robh3606]

I'm reading on the Internet about people who are blowing 20 amp breakers using larger multi-channel power amplifiers.

Really what amps are they using?? I have 3 Crown PS200's a single PS400 an Emotive XPA-3 and a Crown XTI-2002 all on a single 20 amp and no issues at all even stupid loud with action movies so lots of LFE

Rob:)

[1audiohack]

Agreed. One can make an immense amount of noise on a 120V 20A circuit.

Robert, the 10KA number you see is the instant short circuit trip rating. This is of no concern. It is the current rating on the actual toggle portion of the breaker that indicates it's size.

The tripping of the smoker is interesting. If your house has arc fault breakers, those are another adventure all together but the patio will / should be on a GFI. If the smoker (and every other thing on the circuit) has more than 6mA of combined current leakage it will trip a GFI.

Your oven is most likely on a two pole 50A breaker as an example. You would be hard pressed to run a hot plate on a 120V 10A breaker.

Barry.

[JeffW]

Here's a Square D breaker, 20A. It has 10kA on it, too, but it's a 20 amp breaker

http://www.schneider-electric.us/en/product-image/216581-square-d--qo--and-qob-miniature-circuit-breakers

I do the FR/FL pre out of the AVR into an input on my 2 channel preamp into separate 2 channel amp. So by selecting that input on the 2ch preamp, I get TV sound through the "stereo" and control the TV volume with the 2ch preamp. For surround, I set the 2 ch preamp on a setting that gives good balance front to back (usually 70 or so in my case) and then control the overall volume with the AVR volume control.

[robertbartsch]

.....lots of posts on blown 20 amp circuits - Adcom 7807, 7805, big Parasounds, big Krell, etc.... apparently, the biggest power draw is when the amps are first turned on.

I'm probably going to buy a few more Adcam 555s and call it a day....??:applaud:

[1audiohack]

Turn on is a big power hit with Adcoms for sure. When I sequence the 585 on it dims the lights in the master bedroom. Never tripped a breaker though.

I did a test and powered up three Crown CE2000's at once and tripped a 20A 120V breaker. The CE4000's have a Class D style power supply and soft start so I didn't try them.

The I-Tech's soft start also.

Not all breakers are created equal. There are "high mag" breakers for high current start devices like electric motors, AC compressors and such and would be a good match for power amplifiers. These are not available for all residential breaker boxes though.

One other thing that affects a breakers trip threshold is its trip history. They get softer when tripped often. You can also buy breakers that are switch duty but again, not for all residential boxes.

Barry.

[Robh3606]

Are they turning on multiples?? I do mine one at a time manually are they using triggers that are not timed??

Rob:crying:

[Mr. Widget]

.....lots of posts on blown 20 amp circuits - Adcom 7807, 7805, big Parasounds, big Krell, etc.... apparently, the biggest power draw is when the amps are first turned on.

I'm probably going to buy a few more Adcam 555s and call it a day....??:applaud: I have a pair of the biggest of the Parasounds and my lights don't even dim on power up. My 5hp Powermatic table saw does dim the lights a little on initial inrush, but it's a 30 amp 250V circuit so it's draw is rather substantial.


Widget

[rdgrimes]

Other than the added features that most people do not need, I see no benefit in buying the more expensive AVRs. I always spec the least expensive model with line level outputs and whatever other features that are needed to satisfy the system design.

Widget
Trouble is they always package the best DACs and analog boards in the flagship models. Plus the best auto-EQ routines, etc, etc.
If you have enough speaker and amp you can hear the difference in the better AVRs. There's no winning when you're chasing the last 5% of performance.

[rdgrimes]

I'm reading on the Internet about people who are blowing 20 amp breakers using larger multi-channel power amplifiers.

There's something like 3500W of rated power consumption, all turning on at the same time here and all on a single 15A circuit. The lights do dim a bit but I've never popped the breaker. (not from a lack of trying)

I used to have close to 5000W rated running on the same circuit.

[Mr. Widget]

Trouble is they always package the best DACs and analog boards in the flagship models. Plus the best auto-EQ routines, etc, etc.
If you have enough speaker and amp you can hear the difference in the better AVRs. There's no winning when you're chasing the last 5% of performance. I think you need to take it on a case-by-case basis… Some "flagship designs" are really not that special sounding and are simply feature rich. Even if they have the best DAC chipsets, when you pump that through a mediocre analog opamp it kind of spoils the whole thing.


Widget

[robertbartsch]

.....the breakers in my electric box that are marked 10KA are really 20 amp circuits, as someone indicated above.... I turn my amps on one at a time... ....ahhhh, that is, since I read all the Internet posts on blowing out breakers... ....15 or 20 seconds apart, right?


Thanks....

[sebackman]

Hi Guys,

A bit OT I know, but may be of value to some.

-Just wanted to add a few things. Circuit breakers are magnetical devices and react to amps being drawn. There is a small solenoid in them and when too much amps are drawn the force of the solenoid pulls a small metal clip that trips the breaker.

Normally these are all “slow blow” characteristics in the US so there are really no alternative than to swap for a bigger if it blows often. In Europé there are 4 different “blow curves”, from fast to really slow.

These are also subject to large quality differences. A cheap one can trigger early so an alternative may be to buy a “known brand” breaker. Please see link below.

http://audiokarma.org/forums/index.php?threads/is-there-such-a-thing-as-a-slow-blow-circuit-breaker.269510/ (http://audiokarma.org/forums/index.php?threads/is-there-such-a-thing-as-a-slow-blow-circuit-breaker.269510/)

All amps with switch mode power supply (light weight) do have in-rush protection/soft start to protect the electronics so they should not post aproblem.

For amps with conventional power supplies it’s the start-up of the transformer and potentially the charging of the capacitor bay that draws the amperage. There are many different types of transformers and they react differently. Most amperage is drawn by toroidal cores (round) and less by C-cores and E-cores.

The amp spike is only milliseconds long so you do not need to wait more than 1-3 seconds, the breaker is magnetic so there is now heat involved as with an older fuse type.

I built a three stage soft start for some big amps a while back and that had 3 seconds delay for stage two and three. It still sits there on the wall to remind me of all the stupid tests done over the years, but all my current amps,Crown CTS, have switch mode power supplies so it is not needed.

I would argue that most amps/receivers today do have some form in-rush protection. The more sophisticated have active electronics but most just a NTC resistor in series with the 120V/220V incoming. A NTC resistoris a small device that reduces resistance with temperature to almost zero. When the amp is turned on the resistor is maybe 20-50 ohms and as the current flows it gets warm and reduces resistance to zero. Hence the amperage spike is gone.

73376

These look like a small black/gray disc (1/2” up to 1”) standing up and with two legs soldered into the PCB. Since this is an effective and cheap way to protect the electronics almost all “power electronics” today do have them. I would be surprised if your receiver does not have one, but it may be faulty.

If an amp blows speakers on turn-on or off it is normally faulty. On turn-on the speaker protection circuits should not release any signal before the amp is stable and on turn off the capacitor bay does not go flat immediately after turning power of so there should be ample of time to trip the speaker protection before any nasty things reaches the speakers. No amp should really release nasty spikes today if it is a good construction.

Attached is a picture of a NTC resistor and where it sits in a Crown K2amp.

73377

If the breaker is 20 amps today, I would swap the breaker to a new “quality”breaker to start with.

Kind regards and sorry for the OT
//RoB