Connecting pre-amp to aux-in instead of main-in?

[existingbrain]

I would like to extend the amplification power of my Yamaha integrated (RN800A) by connecting its pre-out to an external amplifier. I have been considering several power amp options from Buckeye and Apollon, but due to vanity, have found myself being attracted to "prettier" products such as the Cambridge EVO 150, which runs on Hypex and would roughly double (or at least 1.5x) 4-ohm output compared to my Yamaha. I would like to retain the pre-amp of my Yamaha for its bass management and room correction ability, which the EVO lacks.

Notably, the EVO is an integrated amp that lacks a "main-in" input designed for bypassing the internal pre-amp. However, it does appear to have an "aux-in" input. I asked Cambridge support about this, and they replied that it is theoretically possible to connect a pre-amp to the aux-in as long as I balance the volume control of both amplifiers. This did not sound very reassuring, so I was hoping to get ASR members' thoughts on this and whether anyone has tried something similar. Is this actually safe to do? Are there any risks? And would this kind of setup increase noise due to "doubling up" on the pre-amps?

 

[staticV3]

Yes you can connect the Yamaha's Pre out to the Cambridge's Aux in.

The danger is in that the Yamaha may be able to output voltages that exceed the Cambridge's maximum input voltage, which could result in clipping (no damage, just poor sound).

To check, use a common multimeter and make sure that the Yamaha's Pre out output voltage doesn't exceed 2.0Vrms.

Yes the Cambridge's in this scenario redundant preamp and other electronics may add some noise, compared to a bare bones Power Amp.

Personally I'd connect the Yamaha's Pre out to the Cambridge's XLR inputs instead, using custom-built cables.

That way I could use the Yamaha's full output voltage without the risk of clipping, and I'd get a balanced signal transmission that's immune to interference and ground loops.

But then again, I'd just buy a bare bones Power Amp instead.

Way cheaper, and way fewer redundant/unnecessary components inside that may fail prematurely and take the rest of the system down with them.

BTW, kind of strange that you were looking at Buckeye and Apollon, seeing as Buckeye ships from the US whereas Apollon is located in Slovenia. You're gonna have to pay hefty import taxes for either one of them.

FWIW, here are some other Hypex builders that you could look into for potentially prettier chassis:

-Audiophonics (France)
-boXem Audio (Luxembourg)
-SoundImports (Netherlands)
-Nord Acoustics (UK)
-VTV Amplifier (US)

 

[Speedskater]

Note that many low budget Digital Multi-Meters (DMM) don't have a low voltage AC range.

 

[staticV3]

Note that many low budget Digital Multi-Meters (DMM) don't have a low voltage AC range.

I can recommend the Aneng AN870.

It has AC ranges of 0.02/0.2/2/20/200/2000Vrms.

Frequency response is flat up to 2kHz:


Linearity is lost below about 1mVrms input:

 

[existingbrain]

Thank you @staticV3 for your detailed response. A few follow-ups if you don't mind...

The danger is in that the Yamaha may be able to output voltages that exceed the Cambridge's maximum input voltage, which could result in clipping (no damage, just poor sound).

Is this the same type of clipping that has the potential to damage speakers, or is speaker damage not a concern in this case?

To check, use a common multimeter and make sure that the Yamaha's Pre out output voltage doesn't exceed 2.0Vrms.

Let's say that I measured and found that the max pre-out output was 3.0Vrms when the Yamaha volume knob was at its max position (0db). Can I avoid clipping by making note of the volume position when it measures exactly 2.0Vrms, for example -20db, and making sure I never exceed this volume position?

Yes the Cambridge's in this scenario redundant preamp and other electronics may add some noise, compared to a bare bones Power Amp.

Personally I'd connect the Yamaha's Pre out to the Cambridge's XLR inputs instead, using custom-built cables.

By "custom-built cables", do you mean something like this?

That way I could use the Yamaha's full output voltage without the risk of clipping, and I'd get a balanced signal transmission that's immune to interference and ground loops.

May I ask how you know this without knowing the XLR input voltage of the EVO? Were these specs available on their website (I could not find it readily) or is it just commonly understood that XLR input can handle any voltage? Just to be clear, I am not challenging your assertion; as a newb, I am genuinely curious how one can figure these things out.

But then again, I'd just buy a bare bones Power Amp instead.

You are 100% correct, and I may end up doing this at the end of the day, but, aside from trying to satisfy my vanity, I am also just curious about how these things work.

BTW, kind of strange that you were looking at Buckeye and Apollon, seeing as Buckeye ships from the US whereas Apollon is located in Slovenia. You're gonna have to pay hefty import taxes for either one of them.

I am located in the US, so Buckeye is my default option, but I'm just not a fan of the case. I thought it would be worth it to pay extra for Apollon even with import taxes. This is how I got to thinking, if I'm going to pay extra anyway, maybe I'll also consider amps that look good (to my eye), and then see if I could make that work.

FWIW, here are some other Hypex builders that you could look into for potentially prettier chassis:

-Audiophonics (France)
-boXem Audio (Luxembourg)
-SoundImports (Netherlands)
-Nord Acoustics (UK)
-VTV Amplifier (US)

Thank you for this list. I've seen a few of these and I thought Apollon and Nord Acoustics looked the best, but still not as nice as the EVO 150, which can even display virtual VU meters on its LCD.

 

[staticV3]

Is this the same type of clipping that has the potential to damage speakers

Only if you keep playing horribly distorted music for extended periods of time.

Usually, what happens is you increase the volume, notice heavy distortion, then just back up the volume a few notches. No harm done.

Let's say that I measured and found that the max pre-out output was 3.0Vrms when the Yamaha volume knob was at its max position (0db). Can I avoid clipping by making note of the volume position when it measures exactly 2.0Vrms, for example -20db, and making sure I never exceed this volume position?

Yes.
2V is just 3.5dB down from 3V btw.

By "custom-built cables", do you mean something like this?

More like this.

May I ask how you know this without knowing the XLR input voltage of the EVO? Were these specs available on their website (I could not find it readily) or is it just commonly understood that XLR input can handle any voltage? Just to be clear, I am not challenging your assertion; as a newb, I am genuinely curious how one can figure these things out.

It is commonly understood that XLR inputs can handle at least 4Vrms.

That the Yamaha can output >4Vrms via its RCA Pre out, is unlikely.

 

[Blumlein 88]

Going by the Stereophile measurements of this, it has 33.9 db of gain on both XLR or RCA. So roughly .68 volts input will get you to rated output.

Cambridge Audio EVO 150 streaming integrated amplifier Measurements

Sidebar 3: Measurements

www.stereophile.com

Specs on the pre out of the Yamaha are 1.2 volts. Probably not a big enough mismatch to worry about.

R-N800A | Specifications

manual.yamaha.com

 

[antcollinet]

(or at least 1.5x)

as far as I can see from Yamaha's spec page, and the stereophile measurements you are only going from 220W to about 280W = that is only 1dB - not really worth bothering with if you are trying for more power.

Even if you were getting 50% more power, that is only 1.76dB - maybe 15% louder perceived volume.

I think you need to be looking elsewhere, and as has been stated going from integrated to integrated makes no sense.

 

[garyrc]

Rule of thumb: If you want more power, double it, or more. That gives you 3 dB higher volume (three just noticeable differences).

What is the rated sensitivity ("efficiency") of your speakers? That matters a lot!

For instance, if 107 dB peak Sound Pressure Level ("volume") is the goal, in a 4,000 cu. ft. room, at 13 feet listening distance, my most sensitive speakers [101 dB @ 2.83v (1 watt into 8 Ohms) @ 1 Meter] would need less than 16 watts even if they were relatively long duration peaks. On the other hand, a typical speaker (90 dB @ 1 watt @ 1 meter) would take more like 250 watts.
There are many less sensitive speakers (some good ones, too) in the 80's. For every additional 3 dB you want, double the wattage.

 

[existingbrain]

as far as I can see from Yamaha's spec page, and the stereophile measurements you are only going from 220W to about 280W = that is only 1dB - not really worth bothering with if you are trying for more power.

Technically the RN800A is not 4 ohm rated, but I see you are referring to the "high dynamic power" spec of 220W at 4 ohms... for actual usage (i.e., listening to music), is it fair to consider this the actual 4ohm spec of this amplifier? (I would like nothing more than this to be true )

I got 1.5x guestimate by going off the Audioholics bench test CFP-BW measurement of 175W at 0.1% distortion. I thought CFP-BW at 0.1% would give me a conservative figure to work with. Also, I know this data is based on testing the RN1000A, but from what I can tell the power amp section is more or less identical to the RN800A, and this was the only independent measurement I could find.

Even if you were getting 50% more power, that is only 1.76dB - maybe 15% louder perceived volume.

I think you need to be looking elsewhere, and as has been stated going from integrated to integrated makes no sense.

Thanks, this makes sense. My concern of insufficient power is based on this blog post from KEF that recommends supplying between 60% and 110% of the maximum wattage specified for a speaker. So for example, the speakers I'm considering are 4 ohm and specced at max 300W, and using KEF's logic, I would need an amp that can produce between 180W and 330W. The blog post has some scary verbiage like "More speakers are damaged from under-powering than from over-powering simply because the damage is cumulative and not heard as distortion until it’s typically too late" which makes me wonder whether it's possible to slowly damage speakers over time if I crank the volume a bit and there are intermittent distortion from peaks.

 

[existingbrain]

Going by the Stereophile measurements of this, it has 33.9 db of gain on both XLR or RCA. So roughly .68 volts input will get you to rated output.

May I ask how you got the .68 volt figure? I would love to understand the math.

Specs on the pre out of the Yamaha are 1.2 volts. Probably not a big enough mismatch to worry about.

R-N800A | Specifications

manual.yamaha.com

The spec states "1.0 Vrms/1.2 kΩ". This is a side-question, but can someone explain how this latter number, the "output impedance" affects how I should be thinking about the output voltage in relation to power amp requirements? If the output impedance were lower, would it mean that I could use a power amp with lower gain?

 

[existingbrain]

More like this.

Thanks for the clarification. This looks beyond my technical ability. I assume there is no commercially available equiavlent?

 

[Blumlein 88]

May I ask how you got the .68 volt figure? I would love to understand the math.


The spec states "1.0 Vrms/1.2 kΩ". This is a side-question, but can someone explain how this latter number, the "output impedance" affects how I should be thinking about the output voltage in relation to power amp requirements? If the output impedance were lower, would it mean that I could use a power amp with lower gain?

1.2 kohms is a high output impedance. It means you might want to keep the interconnect cable on the short side of things (2 meters or less). It's effect on gain is going be slight to meaningless.

Okay on the gain, 150 wpc into 8 ohms is about 34 volts. 34 volts/8 ohms= 4.25 amps. 4.25 amps x 34 volts=144.5 watts.

So 34 volts is pretty much max voltage at rated power.

The Stereophile measurements said 33.9 db gain. 33.9 db/20=1.695 Inverse log of that number is 49.55 which is the ratio in voltage. So that amp puts out a voltage 49.55 times greater than the input voltage. 34 volts/49.55=.686 volts.

 

[staticV3]

I assume there is no commercially available equiavlent?

Thee cable needs to match the AVR's output LCR for fully balanced output, so no.

 

[antcollinet]

My concern of insufficient power is based on this blog post from KEF that recommends supplying between 60% and 110% of the maximum wattage specified for a speaker.

Frankly that is nonsense.

The power you supply to the speaker will be based on the speaker sensitivity, the room and listening distance, and the volume you want to listen to.

Typically this might be between 2 and 5 watts as an average with peaks going to 10 to 20x that.

When you are delivering that needed power, the speaker has no way of knowing if the amp is reaching the edge of it's limits, or is only at 10% of it's limits. It makes no difference if the speaker is rated for 100W or 1000W (assuming sensitivity is the same)

 

[JeremyFife]

I'd just add that the Cambridge Evo is a very good looking, fully featured unit. You are paying a lot for features that you just don't plan to use.

Second the suggestions to get a proper power amp instead, or recognise that perhaps your Yamaha is actually fine.

 

[existingbrain]

Frankly that is nonsense.

The power you supply to the speaker will be based on the speaker sensitivity, the room and listening distance, and the volume you want to listen to.

Typically this might be between 2 and 5 watts as an average with peaks going to 10 to 20x that.

When you are delivering that needed power, the speaker has no way of knowing if the amp is reaching the edge of it's limits, or is only at 10% of it's limits. It makes no difference if the speaker is rated for 100W or 1000W (assuming sensitivity is the same)

That makes sense, and is making me feel better about just sticking with my Yamaha.

Do you happen to have any thoughts on using the "high dynamic power" rating of an amp to represent its continuous/normal operating power? For example, can I really take the 220W @4-ohm dynamic rating of the Yamaha and take it to mean that it is comparable to the 280W at 4-ohm spec of the EVO (i.e., Hypex Ncore)? Does this have anything to do with class D amps not having much dynamic headroom above its spec?

 

[existingbrain]

I'd just add that the Cambridge Evo is a very good looking, fully featured unit. You are paying a lot for features that you just don't plan to use.

Second the suggestions to get a proper power amp instead, or recognise that perhaps your Yamaha is actually fine.

Yes, I'm slowly leaning towards getting a power amp or just sticking with the Yamaha, thanks to you fine folks

 

[antcollinet]

Do you happen to have any thoughts on using the "high dynamic power" rating of an amp to represent its continuous/normal operating power?

I read up on it after your last post - it is nothing like a continuous rating. It lasts only a few thousandths of a second - enough perhaps for a percussive transient - no more.

 

[garyrc]

1. Somewhere the sensitivity of your speakers is specified! In the manual, on the back of the speaker, somewhere. Google is your friend. Sensitivity is an important spec, and you can use it to answer some of your questions. Sometimes sensitivity is (incorrectly) called "efficiency," a common (incorrect) name for it for the first many decades of High Fidelity. The sensitivity spec is much more relevant than the power handling capacity of the speaker, dynamic power of your receiver or power amp, etc., partly because manufacturers have (conveniently) not standardized the method of measuring same.
2. How big is your room (in cubic feet)?
3. Is your room "live" (lots of hard surfaces, like glass), "dead" (carpet, soft "overstuffed" couch and chairs), or in-between?
4. How far away from your speakers do you sit?
5. Do you sometimes play music or films with their realistic dynamic range (up to about 100 dB peak for the midrange, and up to 110 dB peak in the deep bass)? Or do you play at a lower volume?
6. I predict that you will be fine keeping and using your Yamaha, but we won't know until you answer these questions, or if you never (well, hardly ever) hear distortion in the loud passages.