New speakers - Should I consider external amplification?

I

Isak Öhrlund

Junior Audioholic
Hi,

I've been running a 7.2.4 setup of low-tier Dali speakers for some years now, powered by a Denon AVR-X4500H and a XTZ Edge A2-300 stereo amplifier for the front L /R. Recently, I upgraded my front L/R from the Zensor 5's (link) to the high-tier Dali Rubicon 5's (link), and I was so pleased with the upgrade that I decided to upgrade the surround and back surround speakers as well, going from the Zensor Pico's (link) to the Dali Menuet's (link) which should be a nice match to the Rubicon 5’s. For heights, I’m using the Dali Alteco C-1's (link).

These six new speakers are all 4 ohms nominal and have a sensitivity rating of 86 dB. The height speakers are 6 ohms nominal and 83 dB sensitive and the center is 6 ohms nominal and 88.5 dB sensitive. In the near future, I also plan on upgrading the center to the Rubicon vokal (link) which is 4 ohms and 89.5 dB sensitive. I cross all speakers over to the subs at 80-110 Hz depending on the size of the speaker.

Now, I am worried that the amplification I have may not be able to let these speakers shine the way they can. But I really have no idea, and I don’t have any experience with different amps. Hence this thread.

In terms of listening, this is a living room system which I use primarily for watching movies. The room is about 3300 cubic feet and has openings to the sides. I sit about 10-12 feet away from the speakers and listen at -20 to -15 dB when I crank it up (which I most often don’t due to my family situation, so the ability to drive these speakers at low SPL with great detail is very important as well).

So my questions are:
1. Would you recommend that I add external amplification considering the new speakers, and considering how the AVR pre-outs operate etc?
2. If so, why, and for which speakers?
3. If so, what amp would you suggest? Small cabinet dimensions is important to me since I use an AV cabinet, so I am thinking multiple stereo amps (perhaps additional XTZ Edge amps) or one or several multichannel amps that are similar in size to the Denon AVR-X4500H.

Your thoughts, opinions and recommendations are much appreciated!
 
ryanosaur

ryanosaur

Audioholic Overlord
How loud do you run things?
How hot is your denon getting with the speakers you are driving from the on-board amps?

It is generally said that the Denon should be able to handle it unless they are dropping below 4 ohms and you don't have any Subwoofer help down low while playing loud. (Yes, I see you put some info up above, but I just want to double check cos it only takes one day of play to fry your gear. ;) )

Anyway, Generally, if you want to look at putting Amps on anything, start as you did with Mains, and Center. If your Surrounds are potentially challenging, you could add an Amp for those, but they don't usually have so much programming as to be severely taxing (unless you are playing music in multi-channel stereo where every speaker is demanding as much juice as they can get).

If you like the XTZ Amp, you should keep it. You could slide that back to Surround if you want. Get a 3-channel to handle the Front 3. Let the Denon run the Rears and any Atmos. (This is close to what I do with my Marantz.)

I'm in the process of switching to Hypex Class D Amps. I think over there in the EU, there are some good options for Hypex and Purifi units. They don't need to be crazy expensive. There is Nord and Apollon in the UK. Boxem is another company I've seen mentioned from time to time.

Regardless, I would try without first. See how the AVR is handling things. Putting a fan on top of the Denon can help keep things cool and happy as well.

There are also some online calculators to help you determine what you need to comfortably hit your desired SPL.
(I forget what the correction is for 4ohm speakers... I think this is based on an 8ohm load... perhaps a friend will jump in and offer that up. :) )
 
j_garcia

j_garcia

Audioholic Jedi
How far you sit, how loud you listen matter. As ryan mentioned, try it without and see if your expected listening levels are already working fine. If it struggles, then you should consider amps.
 
Verdinut

Verdinut

Audioholic Ninja
There are also some online calculators to help you determine what you need to comfortably hit your desired SPL.
(I forget what the correction is for 4ohm speakers... I think this is based on an 8ohm load... perhaps a friend will jump in and offer that up. :) )
The calculator works with any speaker impedance. To clarify, the SPL for a driver is calculated at 1 watt amp output at a distance of 1 meter. So, an 8 ohm speaker will output so much whereas a 4 ohm will output 3 dB more. It's automatically implied with the manufacturer's specs. 1/4 vs 1/8 = double the power to the driver.
 
Last edited:
ryanosaur

ryanosaur

Audioholic Overlord
The calculator works with any speaker impedance. To clarify, the SPL for a driver is calculated at 1 watt amp output at a distance of 1 meter. So, an 8 ohm speaker will output so much whereas a 4 ohm will output 3 dB more. It's automatically implied with the manufacturer's specs.
I think it might have been PENG that has commented that impedance was a flaw in that calculator. According to the site:
1. The speaker sensitivity, typically expressed in decibels (dB) with 1 watt (or 2.83 volts across an 8 ohm speaker) measured on-axis one meter away...
If my understanding is correct, that 1w is the key piece as you would need to adjust for the change in impedance, correct?
I seem to recall @PENG building his own more complicated calculator that allowed for impedance changes.
 
lovinthehd

lovinthehd

Audioholic Jedi
Sensitivity is usually defined as 2.83V at one meter....2.83V at 8 ohm is one watt, 2 watts at 4 ohm. Sometimes you need to adjust depending on how the speaker is spec'd.
 
Verdinut

Verdinut

Audioholic Ninja
Hi,

I've been running a 7.2.4 setup of low-tier Dali speakers for some years now, powered by a Denon AVR-X4500H and a XTZ Edge A2-300 stereo amplifier for the front L /R. Recently, I upgraded my front L/R from the Zensor 5's (link) to the high-tier Dali Rubicon 5's (link), and I was so pleased with the upgrade that I decided to upgrade the surround and back surround speakers as well, going from the Zensor Pico's (link) to the Dali Menuet's (link) which should be a nice match to the Rubicon 5’s. For heights, I’m using the Dali Alteco C-1's (link).

These six new speakers are all 4 ohms nominal and have a sensitivity rating of 86 dB. The height speakers are 6 ohms nominal and 83 dB sensitive and the center is 6 ohms nominal and 88.5 dB sensitive. In the near future, I also plan on upgrading the center to the Rubicon vokal (link) which is 4 ohms and 89.5 dB sensitive. I cross all speakers over to the subs at 80-110 Hz depending on the size of the speaker.

Now, I am worried that the amplification I have may not be able to let these speakers shine the way they can. But I really have no idea, and I don’t have any experience with different amps. Hence this thread.

In terms of listening, this is a living room system which I use primarily for watching movies. The room is about 3300 cubic feet and has openings to the sides. I sit about 10-12 feet away from the speakers and listen at -20 to -15 dB when I crank it up (which I most often don’t due to my family situation, so the ability to drive these speakers at low SPL with great detail is very important as well).

So my questions are:
1. Would you recommend that I add external amplification considering the new speakers, and considering how the AVR pre-outs operate etc?
2. If so, why, and for which speakers?
3. If so, what amp would you suggest? Small cabinet dimensions is important to me since I use an AV cabinet, so I am thinking multiple stereo amps (perhaps additional XTZ Edge amps) or one or several multichannel amps that are similar in size to the Denon AVR-X4500H.

Your thoughts, opinions and recommendations are much appreciated!
Your Dali Rubicon 5 speakers are designed to operate with a maximum power output of 150 watts. That is the instantaneous peak amplifier output it will take. Beyond that power, it will be seriously damaged. Your AVR can output that 150 watt power at 4 ohms if you set the speaker impedance switch to 8 ohms, but it doesn't seem to be designed to drive speakers with an impedance of less than 6 ohms.

The conclusion is that your receiver is supposed to be adequate to drive your Dalis if you don't listen at very high SPL, otherwise you risk damaging your speakers and the AVR as well. There wouldn't be any advantage with external amplification for the Rubicon 5s.
 
Last edited:
ryanosaur

ryanosaur

Audioholic Overlord
Sensitivity is usually defined as 2.83V at one meter....2.83V at 8 ohm is one watt, 2 watts at 4 ohm. Sometimes you need to adjust depending on how the speaker is spec'd.
That's what I was recalling (hopefully correctly) is that you need to make a sensitivity adjustment in that particular calculator.
 
Verdinut

Verdinut

Audioholic Ninja
I think it might have been PENG that has commented that impedance was a flaw in that calculator. According to the site:

If my understanding is correct, that 1w is the key piece as you would need to adjust for the change in impedance, correct?
I seem to recall @PENG building his own more complicated calculator that allowed for impedance changes.
The calculation with 1 watt is OK. The use of 2.83 volts squared is also 1 watt for the 8 ohm load but means 2 watts for the 4 ohm load.
 
Verdinut

Verdinut

Audioholic Ninja
Sensitivity is usually defined as 2.83V at one meter....2.83V at 8 ohm is one watt, 2 watts at 4 ohm. Sometimes you need to adjust depending on how the speaker is spec'd.
Not many four ohm loudspeakers did exist 60 years ago. The current 2.83 volt sensitivity ratings came with their popularity.

In the pro audio history, we have seen loudspeakers with impedances of 12, 15, 16 and 20 ohms. In the 1960's, Altec Lansing was still releasing 16 ohm speakers for home use, and started producing 8 ohm drivers.
 
Last edited:
P

PENG

Audioholic Slumlord
That's what I was recalling (hopefully correctly) is that you need to make a sensitivity adjustment in that particular calculator.
That is correct, one way to adjust for impedance is to add or subtract x dB to the sensitivity spec of the speaker, the other is to multiply the calculated "watts" by a factor as follow:

For example, for a 4 ohm speaker with sensitivity 87 dB/2.83 V/m, sitting from 4 meters, an online calculator will show power required to get reference level 85 dB average = 10 W, with no room gain. So for a 6 ohm nominal speaker, it will be about 1.33X10 = 13.3 W.

Likewise, you can adjust the sensitivity of 87 dB by -1.25 = 85.75 dB and the calculator will also show the power required is 13.3 W

As Ryan mentioned, I do have an Excel based calculator that allows me to enter any impedance value but it cannot be attached. For most people, the table below should suffice because manufacturers typically specify impedances such as 4,6 or 8 ohms. I have never seen any impedance specs of 7.5 ohm or even 7 ohm though some of them do specify the minimum value, such as 8 ohm nominal 3.5 ohm minimum.

Imp (ohms)Adjustment factor for the calculated power based on 8 ohmsSens adj
81.000.00
71.14-0.58
61.33-1.25
51.60-2.05
42.00-3.02
32.67-4.26
24.00-6.03
18.01-9.04
 
I

Isak Öhrlund

Junior Audioholic
Thank you all. Most of the time I listen at low to moderate levels, but I just don't want to risk damaging my AVR and/or speakers when I crank it up once in a while. According to Denon "the minimum impedance [of a speaker] (across the entire frequency spectrum) should not fall below a value of 3.2 Ohms" (link). I have no idea whether any of my Dali speakers might fall that low and I am hesitant of "giving it a try" :rolleyes:

IF I would like to add external amplification, could you provide me with some guidance with regards to my AVR's pre outs and the external amplification specifications? My understanding is that the pre outs on my X4500H do not go beyond 1,4-2 volt before "clipping" (?), which will be a problem if the external amp requires more than that to reach full power (?). After having read the ASR review of my XTZ Edge A2-300 (link), my understanding is that this amp does give full power already at 1,2 volts (?). So, adding multiple XTZ Edge A2-300 should work just fine, even though my AVR does not have a preamp mode?
 
ryanosaur

ryanosaur

Audioholic Overlord
The only time the newer preamp mode is particularly useful is if you are going to run amps on all channels.
I don’t think you need to do that.
You already hav 2-channels, iirc, so I would likely consider moving that to stay with the same speakers now at surround, and consider adding 3-channel amplifier to do the new mains and center.
Any rears and atmos/auro speakers can be handled by the AVR.
 
lovinthehd

lovinthehd

Audioholic Jedi
Thank you all. Most of the time I listen at low to moderate levels, but I just don't want to risk damaging my AVR and/or speakers when I crank it up once in a while. According to Denon "the minimum impedance [of a speaker] (across the entire frequency spectrum) should not fall below a value of 3.2 Ohms" (link). I have no idea whether any of my Dali speakers might fall that low and I am hesitant of "giving it a try" :rolleyes:

IF I would like to add external amplification, could you provide me with some guidance with regards to my AVR's pre outs and the external amplification specifications? My understanding is that the pre outs on my X4500H do not go beyond 1,4-2 volt before "clipping" (?), which will be a problem if the external amp requires more than that to reach full power (?). After having read the ASR review of my XTZ Edge A2-300 (link), my understanding is that this amp does give full power already at 1,2 volts (?). So, adding multiple XTZ Edge A2-300 should work just fine, even though my AVR does not have a preamp mode?
Generally if you crank it and it starts to sound bad, you've gone too far with the volume control....easiest way to avoid damage is just paying attention (and if having parties with lots of people who might be tempted to go too loud, avrs generally have a volume limit you can set).

The amp spec you're looking for is the sensitivity (how many volts to produce full power from the amp), which Amir confirmed was at 1.2 V. As long as you're not put off by the somewhat poor performance, multiples of this unit should work fine.

You don't need a pre-amp mode generally as was mentioned, and that range from Denon at best only provides the pre-amp mode for two channels IIRC (you need to go to their top of the line models like the 8500/A110 for individual channels having the ability to use the pre-amp mode or not). I have an older Denon 4520 with the pre-amp mode feature but it's only applicable when using only external amps, (i.e. none of the internal amps).

I tried finding measurements for the Zensor 5 but didn't find one; I did find the Zensor 1 measurements where they are rated as 6 ohm, but don't go below 5 ohms (look for the impedance/phase measurement graph). So maybe yours are similar, hard to know unless Dali provides the minimum impedance info or revealed via measurements by a third party (all too often you need to find measurments, tho).
 
Last edited:
-Jim-

-Jim-

Audioholic General
Just wondering what the settings are for the speakers ? (Large or Small) How is the bass management setup?
 
newsletter

  • RBHsound.com
  • BlueJeansCable.com
  • SVS Sound Subwoofers
  • Experience the Martin Logan Montis
Top