Will my 1V pre-out be able to harness all of Hypex power amp's power?

[Symphoniac]

Finally got around to measuring my pre-amp output voltage with a multimeter. Using a 100hz tone (as generated in the screenshot above), I varied the volume and took several measurements. I found the following:

- Volume 0db : 4V
- Volume -5db : 2.2V
- Volume -10db : 1.2V
- Volume -20db : 0.5V

With any volume below this (the lowest possible setting on my Yamaha is -69.5db), the measurements were too volatile. For example, when I set the volume to -30db, the multimeter readings jumped around between 0.04V and 1.5V. I am guessing this is likely due to the lack of precision of my instrument? (I used the Etekcity multimeter recommended above.)

So I guess this means that the pre-out voltage does in fact go up to 4V, which is good to know! However, what concerns me now is that the voltage seems to jump a huge amount between -10db and 0db (1.2v and 4V). Does this mean that I will hear huge jumps in SPL when I try to use this pre-out with a power amp such as those that require 2V in for max power? In other words, will minute volume adjustments not be possible at louder listening levels? Hope this question makes sense.

 

[GXAlan]

Finally got around to measuring my pre-amp output voltage with a multimeter. Using a 100hz tone (as generated in the screenshot above), I varied the volume and took several measurements. I found the following:

- Volume 0db : 4V
- Volume -5db : 2.2V
- Volume -10db : 1.2V
- Volume -20db : 0.5V

With any volume below this (the lowest possible setting on my Yamaha is -69.5db), the measurements were too volatile. For example, when I set the volume to -30db, the multimeter read between 0.04V and 1.5V. I am guessing this is likely due to the lack of precision of my instrument? (I used the Etekcity multimeter recommended above.)

So I guess this means that the pre-out voltage does in fact go up to 4V, which is good to know! However, what concerns me now is that the voltage seems to jump a huge amount between -10db and 0db (1.2v and 4V). Does this mean that I will hear huge jumps in SPL when I try to use this pre-out with a power amp such as those that require 2V in for max power? In other words, will minute volume adjustments not be possible at louder listening levels? Hope this question makes sense.

No. You should hear an extra dB with each extra setting. It’s just that the power needed keeps going up at a faster rate. This is why 8W 300B SET amps are good for a lot of music and yet people want 1 kW mega amp monsters for hitting 100+ dB in large rooms with inefficient speakers.

 

[Blumlein 88]

1.2 v is just about 10 db from 4 volts. Decibels are logarithmic not linear. Nothing weird here and you'll not have any problems in volume jumps from it.

 

[Symphoniac]

Thanks @GXAlan and @Blumlein 88, good to know that what I measured correlates with reality.

Does anyone happen to know why Yamaha would spec the pre-out voltage at 1V? Even if they are trying to be conservative, wouldn't they want to rate it a bit higher than 1V, but still well within the 4V max (such as 2V?) so that consumers know that it'll work with a wider variety of power amps, and presumably want to consider it over a competing model?

 

[Blumlein 88]

They might rate it a bit lower if it has too much distortion at its max voltage. From 1v to 3 or 4 volts is a big jump. So don't know why they would do that.

 

[formdissolve]

The Yamaha amp outputs 100w at 8ohm at 0.07% THD, but can get to 145w peak.

How loud do you listen? How efficient are your speakers?

From what I can tell on the specs for the Yamaha, you'll get about the same distortion over the pre-out. I wonder if you'll just have a distortion machine pushing past a certain voltage and just waste $1250 on the Apollon.

Manual

 

[Symphoniac]

The Yamaha amp outputs 100w at 8ohm at 0.07% THD, but can get to 145w peak.

How loud do you listen? How efficient are your speakers?

From what I can tell on the specs for the Yamaha, you'll get about the same distortion over the pre-out. I wonder if you'll just have a distortion machine pushing past a certain voltage and just waste $1250 on the Apollon.

Manual

Audioholics previously measured the R-N1000A, which presumably shares the same pre-amp and amp section with the R-N800A (the one I have) and produced the following graph for pre-out distortion. Seems like it's about 0.006% at 3.6V (for non-pure-direct). Does this assuage any concerns about pushing distortion at higher voltages?

 

[formdissolve]

Ah, I didn't see that pic. If it uses the same pre-amp section then it will be lower distortion than your speakers. I'd just set the Apollon to highest gain then as others have stated and go from there.

12.8dB = 11.5Vrms
20,5dB = 4Vrms
27,5dB = 2.4Vrms
29dB = 2Vrms

 

[Symphoniac]

Ah, I didn't see that pic. If it uses the same pre-amp section then it will be lower distortion than your speakers. I'd just set the Apollon to highest gain then as others have stated and go from there.

12.8dB = 11.5Vrms
20,5dB = 4Vrms
27,5dB = 2.4Vrms
29dB = 2Vrms

Quick follow up question on using the highest gain setting (i.e., 29db). Given that my pre-out goes up to 4V, would it not be safer to set the gain at a lower value so that I can't exceed the capabilities of the power amp (not sure if this is the right way to put it)? For example, what would happen if I set the power amp gain to 2Vrms and try to increase the volume past 2V on the pre-amp volume? Is this safe? Would it not be better to set the gain to 4Vrms so that the pre-out maxes out at the same voltage as the power amp and I couldn't push the volume/voltage past the power amp input voltage? I suspect I'm misunderstanding something here.

 

[formdissolve]

Quick follow up question on using the highest gain setting (i.e., 29db). Given that my pre-out goes up to 4V, would it not be safer to set the gain at a lower value so that I can't exceed the capabilities of the power amp (not sure if this is the right way to put it)? For example, what would happen if I set the power amp gain to 2Vrms and try to increase the volume past 2V on the pre-amp volume? Is this safe? Would it not be better to set the gain to 4Vrms so that the pre-out maxes out at the same voltage as the power amp and I couldn't push the volume/voltage past the power amp input voltage? I suspect I'm misunderstanding something here.

You could start with the 4v gain and see how that is, but honestly if you're playing music at full 2 volts it would probably be pretty damn loud (depending on the track I suppose). If the sensitivity is at 2v though, all you need is 2v from your Yamaha to hit max capacity (that's the gain) on the amp.

With 4v, yes you have more headroom, but are your sources 4v? Does the internal DAC and all that even push 4v out? I assume you want to keep the Yamaha because it has all the streaming and all that built in.



What speakers do you have? What are the efficiency ratings?

 

[Symphoniac]

You could start with the 4v gain and see how that is, but honestly if you're playing music at full 2 volts it would probably be pretty damn loud (depending on the track I suppose). If the sensitivity is at 2v though, all you need is 2v from your Yamaha to hit max capacity (that's the gain) on the amp.

I don't think I would play that loud on average, just want to make sure I have enough headroom for peaks + a lil extra for peace of mind. I listen to a lot of classical music that has very wide dynamic range.

With 4v, yes you have more headroom, but are your sources 4v? Does the internal DAC and all that even push 4v out? I assume you want to keep the Yamaha because it has all the streaming and all that built in.

Yes I want to keep the Yamaha to serve as a streamer (mostly for airplay functionality) and pre-amp. My only two sources are a CD player that is connected via optical-in and a RPi used as a Roon end-point connected via USB-in. I'm not really sure what the output voltage on the RPi is, but the CD player pushes 2V out according to its manual. I don't really understand how the source voltage interacts with the pre-out voltage. The CD player is using the DAC in the Yamaha, so does that modify the pre-out voltage further? And does this ultimately affect the headroom in the power amp?

What speakers do you have? What are the efficiency ratings?

My speakers are rated by the manufacturer as 4 ohms nominal with a 3.2 minimum and a sensitivity of 86db. Whenever I play around with one of those power/SPL calculators, it seems to indicate I would need up to 100W at 8 ohms to hit 100db peaks at my listening distance of 9 feet. Correct me if I'm wrong, but I take this to mean that I would need up to 200W at 4 ohms. Again, I am definitely not routinely listening to music that loud, but just want to have peace of mind that I have that extra headroom.

 

[formdissolve]

I don't think I would play that loud on average, just want to make sure I have enough headroom for peaks + a lil extra for peace of mind. I listen to a lot of classical music that has very wide dynamic range.


Yes I want to keep the Yamaha to serve as a streamer (mostly for airplay functionality) and pre-amp. My only two sources are a CD player that is connected via optical-in and a RPi used as a Roon end-point connected via USB-in. I'm not really sure what the output voltage on the RPi is, but the CD player pushes 2V out according to its manual. I don't really understand how the source voltage interacts with the pre-out voltage. The CD player is using the DAC in the Yamaha, so does that modify the pre-out voltage further? And does this ultimately affect the headroom in the power amp?


My speakers are rated by the manufacturer as 4 ohms nominal with a 3.2 minimum and a sensitivity of 86db. Whenever I play around with one of those power/SPL calculators, it seems to indicate I would need up to 100W at 8 ohms to hit 100db peaks at my listening distance of 9 feet. Correct me if I'm wrong, but I take this to mean that I would need up to 200W at 4 ohms. Again, I am definitely not routinely listening to music that loud, but just want to have peace of mind that I have that extra headroom.

I could be way wrong, but I'm guessing the internal DAC operates at 2v since that amp doesn't have any balanced inputs/outputs (which typically are 4v, with some exceptions of course). That means that your digitally connected optical and USB are internally running at 2v to the speaker amplifier inside your Yamaha and probably to the preamp out. In that case I'd use a gain setting for 2v on your external amp.

However, you could always use 4v gain at first and see how that goes.. it's pretty easy to turn up the gain via the rear switches on Buckeye or Apollon amps if you find the Yamaha runs out of gas over preamp.

I still think your Yamaha's amp section has enough juice for your speakers at 4ohm 220 watts, but nothing wrong with experimenting. Buckeye sells good stuff.. I'm kind of in the market for one of their NCx500 stereo amps.