Sierra-2s with an 8 watt single-ended triode amp?

[jmac2000]

I've been intrigued by Ascend speakers for a few years but my stereo system upgrades sort of took me on a tangent that now might not be compatible with 87dB speakers. I'm currently running 300b tube based single-ended triode amp and pre-amp separates (DIY kits thought Bottlehead).

However, through 91dB monitors (Energy RC10) I'm now getting surprisingly good results. I have all the gain I could want/need in my modest listening area (~8' listening position from speakers). I'm even pleasantly surprised by the amount of bass I'm hearing from these 6" woofers that wasn't there when powering the Energy speakers through my Denon AVR. I've even crossed a future 0.1 or 0.2 subwoofer package off my upgrade list.

Originally I thought my upgrade path would next have to be to higher sensitivity speakers but now this has me thinking. Might Sierra 2s be back in the running? Has anyone tried powering Sierra 2s through a low watt tube amp?

[Beave]

FWIW, I used to own Energy RC-10s, along with Sierra 1s. The Sierras trounced the Energys in practically every way.

But where did you read that the RC-10s are 91dB monitors? They aren't close to that. The NRC estimated their sensitivity at 85.5dB for a 2.83V input, which happens to be exactly the same as their estimate for the Sierra 1. My listening comparisons of the two side-by-side confirmed they're pretty close in loudness for the same input level.

In any case, you will get *decent* levels with your amp, but peaks will almost certainly be compressed if you play the speakers at anything above modest levels. Even at modestly loud levels, you might average only 1 watt output from your amp, but peaks can easily go 10 times higher.

One final note: The bass from the RC-10s is mostly mid and upper bass, with an emphasis on upper bass. True low bass (that you would get from a subwoofer) is practically non-existent with the RC-10s. Even the Sierra 1s, with their much better bass, don't provide much output in the lowest octave. Until you hear/experience true low bass from a subwoofer, you might think you're getting good bass from these small speakers. But you're really not. Now, you might say if you don't know what it's like, you won't miss it, and that's true to some extent.

[jmac2000]

FWIW, I used to own Energy RC-10s, along with Sierra 1s. The Sierras trounced the Energys in practically every way.

But where did you read that the RC-10s are 91dB monitors? They aren't close to that. The NRC estimated their sensitivity at 85.5dB for a 2.83V input, which happens to be exactly the same as their estimate for the Sierra 1. My listening comparisons of the two side-by-side confirmed they're pretty close in loudness for the same input level.

In any case, you will get *decent* levels with your amp, but peaks will almost certainly be compressed if you play the speakers at anything above modest levels. Even at modestly loud levels, you might average only 1 watt output from your amp, but peaks can easily go 10 times higher.

One final note: The bass from the RC-10s is mostly mid and upper bass, with an emphasis on upper bass. True low bass (that you would get from a subwoofer) is practically non-existent with the RC-10s. Even the Sierra 1s, with their much better bass, don't provide much output in the lowest octave. Until you hear/experience true low bass from a subwoofer, you might think you're getting good bass from these small speakers. But you're really not. Now, you might say if you don't know what it's like, you won't miss it, and that's true to some extent.

Thanks for the reply Beave,
I pulled the RC-10 sensitivity right off the the spec sheet on the Energy website but given the state of that company I'm not even sure who is running that site.

Regarding the bass, I'm not fooling myself into thinking I'm hearing true low end bass from the RC-10, I just made that point to say that I think I would be happy with Sierra 2s alone without subwoofer(s). I have dual Hsu subs in my home theater, I know what true bass feels like. I just don't think I'm missing it in my stereo setup. Probably a function of room layout, music taste, amp, etc.

I don't have any experience with over-driving a tube amp to distortion but I've been told they distort in a much more euphonic way than classic transistors. I'm not sure if that *fact* (using the term loosely) will buy me some flexibility in going with a lower than recommended sensitivity speaker such as the Sierra 2.

Thanks,
Jamus

[Beave]

Oh, ok, so the RC-10 sensitivity comes from Energy. That makes them one of a million other speaker companies that exaggerates their specs. It's probably really more like 91dB, in room, with both speakers playing, and measured at only one frequency, which just happens to coincide with the frequency where their output is the highest. Speaker companies stretch the truth on that measurement just like amplifier companies often stretch the truth on their power claims.

Yeah, if you're happy with the RC-10 bass, you'll likely be happy with the Sierra bass. It's much tighter and punchier, and it goes a little deeper too. But the Sierra doesn't have the upper-bass emphasis that the RC-10s have, so that might take a little getting used to. The RC-10s upper bass emphasis gives them a "warm" overall balance, but it also makes them a little "chesty," or "congested," or "muddy." The Sierras might sound a little leaner in comparison, but they're much cleaner and tighter in the bass, and their midrange is much more clear as well. The RC-10s highs are pretty good from what I remember, definitely their strength.

I think you're right about tube distortion vs transistor (I'm an EE but I've never worked with tubes). If you get enough volume to satisfy you with the RC-10s, you will get enough with the Sierras as well - unless of course the cleaner sound of the Sierras prompts you to crank it up more than you do with the RC-10s. That's always a possibility!! :-)

[justthinking]

IMO, you should decide on speakers first then worry about amplification and everything else

Since Ascend does offer 30 days in home trial, order the Sierra-2 and test the combo out

At worst you will be out is $70-$80 of 2-way shipping which is well worth it

If you find Sierra-2 to be the sound you are after, then you can decide if you need more power than the 8 watts per channel your tube amps can deliver...

On a side note, a while ago I did have the chance to listen to a pair of Sierra-2 driving by PrimaLuna integrated amp (forgot which model), albeit only for a brief few songs, they did sound really good, but I would think it has more to do with Sierra-2 than the tube amp... :)

[jmac2000]

IMO, you should decide on speakers first then worry about amplification and everything else

Ahh, I wish I had that luxury and foresight :) For me, it's been a step-wise journey of incremental upgrades.


Since Ascend does offer 30 days in home trial, order the Sierra-2 and test the combo out

At worst you will be out is $70-$80 of 2-way shipping which is well worth it

If you find Sierra-2 to be the sound you are after, then you can decide if you need more power than the 8 watts per channel your tube amps can deliver...

Good advice and the route I will probably end up going

That PrimaLuna amp was probably under 20 watts? That might bode well for my situation...

Thanks,
Jamus

[N Boros]

I think that justthinking's suggestion of picking the speakers first and then worrying about the amplification makes perfect sense. The good news is that there are other tube options that have significantly more power if you need it. Several folks around here have used Peachtree amps and seemed to like them: http://www.peachtreeaudio.com/nova-amplifier-with-dac.html

This should give you plenty of power for cranking things up or dynamic peaks. You will spend some money for it though.

[jmac2000]

I think that justthinking's suggestion of picking the speakers first and then worrying about the amplification makes perfect sense. The good news is that there are other tube options that have significantly more power if you need it. Several folks around here have used Peachtree amps and seemed to like them: http://www.peachtreeaudio.com/nova-amplifier-with-dac.html

This should give you plenty of power for cranking things up or dynamic peaks. You will spend some money for it though.

I've just spent over $3k on the Bottlehead Kaiju amp and Bottlehead Beepre preamp and 6 months to build them myself. http://bottlehead.com/product/kaiju-300b-amplifier-kit/
A new amp is definitely not in my future ;)

Of all the speakers I'm looking at the Sierra 2s have the lowest sensitivity. Just trying to figure out if they should remain in the mix or if I need to exclude them for that reason.

[Blutarsky]

According to the Kaiju website, the amp should drive Sierra 2's easily.

[monkuboy]

For what it's worth, I am running the Sierra 2's with a VTA ST-120 amp in triode mode, which is 32 watts per channel. I love the way it sounds and there is no lack of power or dynamics. It drives the speakers effortlessly. It's my first tube amp and also by far the lowest powered separate amp (I've even had the Emotiva XPA-1's) but it's my favorite.

[justthinking]

Of all the speakers I'm looking at the Sierra 2s have the lowest sensitivity. Just trying to figure out if they should remain in the mix or if I need to exclude them for that reason.

How good is Sierra-2? Maybe my story will help you make the decision to give it a try

Before I heard Sierra-2 at Ascend's office last August, I shuffled through a bunch of speakers looking for the perfect pair for my 2 channel setup..

The list includes MA RS1 & GS10, KEF IQ3, R300 & LS50, Paradigm Studio 20 & Signature S2, Focal Aria 906, B&W CM6S2 & 805D2, ML Motion 35XT, Totem Element Ember & Fire some I did in store audition while others I had them in my room for extensive in home listening

At the end, I went with a pair of 805D2 as I thought I have found the speaker for my taste and was really happy with them

It all changed last August when I was traveling down to Southern California and decide to finally listen to these Sierra-2 I heard so much about. I spend about 2 hours at Acend's office listening to Sierra-2, visiting their warehouse and assembly/test area and chatted with Dave, I was so impressed with what I heard I ordered a pair of S-2 shortly after

Once I have the S-2 home, I was truly amazed by how good they are, it is a toss up between the S-2 and 805D2 as far as overall performance in my book with S-2 comes out on top in some area and 805D2 holds the edge in others, consider 805D2 sells for more than three times of S-2, it is really astonishing what Dave was able to accomplish with the RAAL tweeter and custom SEAS woofer

[davef]

I've been intrigued by Ascend speakers for a few years but my stereo system upgrades sort of took me on a tangent that now might not be compatible with 87dB speakers. I'm currently running 300b tube based single-ended triode amp and pre-amp separates (DIY kits thought Bottlehead).

However, through 91dB monitors (Energy RC10) I'm now getting surprisingly good results. I have all the gain I could want/need in my modest listening area (~8' listening position from speakers). I'm even pleasantly surprised by the amount of bass I'm hearing from these 6" woofers that wasn't there when powering the Energy speakers through my Denon AVR. I've even crossed a future 0.1 or 0.2 subwoofer package off my upgrade list.

Originally I thought my upgrade path would next have to be to higher sensitivity speakers but now this has me thinking. Might Sierra 2s be back in the running? Has anyone tried powering Sierra 2s through a low watt tube amp?

Hi jmac2000,

Although Energy might list the sensitivity of the RC10 at 91dB - in all actuality, they are not even close to this. There are many ways manufacturers fudge these numbers. The proper way to measure / publish sensitivity is by listing the speaker's sensitivity as measured anechoically.

As measured at the NRC, the Energy RC10's anechoic sensitivity is 85.5dB. The Sierra-2's sensitivity is 86dB (anechoic). If you are OK with the output levels of your RC10 with your current amp, you will be fine with the Sierra-2 as well, (Sierra-2 actually have slightly higher sensitivity)

Here is a link to the RC10's true sensitivity measurements:

http://www.soundstagenetwork.com/measurements/energy_rc_10/

Hope this helps!

[N Boros]

Hi jmac2000,

Although Energy might list the sensitivity of the RC10 at 91dB - in all actuality, they are not even close to this. There are many ways manufacturers fudge these numbers. The proper way to measure / publish sensitivity is by listing the speaker's sensitivity as measured anechoically.

As measured at the NRC, the Energy RC10's anechoic sensitivity is 85.5dB. The Sierra-2's sensitivity is 86dB (anechoic). If you are OK with the output levels of your RC10 with your current amp, you will be fine with the Sierra-2 as well, (Sierra-2 actually have slightly higher sensitivity)

Here is a link to the RC10's true sensitivity measurements:

http://www.soundstagenetwork.com/measurements/energy_rc_10/

Hope this helps!

Dave,

Soundstage does an excellent job with their measurements! Not only do they do listening window, impedance and phase, but they also do the THD+ noise and the deviation from linearity. I did a little digging and it looks like the CBM-170s and the Sierra 1s were measured by Soundstage. The THD + noise curves are nice to look at since you can then match the main speakers well with the subwoofer in terms of output capabilities, right before higher distortion sets in. Audioholics has a table to help us get an idea of how much THD we are getting at various frequencies on the graph, using the table halfway down the page here: http://www.audioholics.com/tower-speaker-reviews/titus-8t-review/titus-8t-measurements We more of less know the THD measurements for the Rythmik F12, since it should measure pretty close to the DIY Rythmik here: http://www.hometheatershack.com/forums/subwoofer-tests-archived/5756-diy-rythmik-audio-direct-servo-12-sealed-56l.html. We know how the Rythmik FV15HP measures here http://www.data-bass.com/data?page=system&id=51&mset=49 (as well as many other subwoofer brands on data-bass). We could then use the Rythmik table to compare ported models to the FV15HP and sealed subs to the DIY F12:

At 20 Hz, our subs vary in their maximum output capability. The output at 20 Hz is shown relative to F12.

F12: 0db (baseline)
F8/FM8: -1.5db
L12: -1db
LV12R: +2.5db
L22: + 4db
LVX12: +4db
E15HP: + 4db
F15HP: +4.5db
FVX15: +6.5db
FV15HP: +9.5db
F25: +8db

This gives us a pretty good idea of how each Rythmik sub will measure, more or less. Data-bass provides even more helpful graphs, since they give THD+noise for each subwoofer at 5dB increments, so we can really get an idea of how much the subwoofer has before it doesn't have much more clean output. The only problem is that we don't know how the Ascend lineup will measure in terms of THD + noise to match up with a Rythmik sub. Do you know know the Sierra 2 will measure as far as THD + noise? I'm mostly interested in at 75dB and 95 dB, since reference volume at home for movies is 75 dB continuously with up to 95 dB peaks. Reference volume is the loudest that I listen to movies from about 2.5 or 3 meters away, so I would be happy is I knew how much distortion there was at 2 meters like things are usually measured. Like I said before, I want to make sure I'm not potentially putting lots of distortion through the speakers and to be able to find a Rythmik sub that can line up in terms of output capabilities before distortion sets in.

[jmac2000]

Hi jmac2000,

Although Energy might list the sensitivity of the RC10 at 91dB - in all actuality, they are not even close to this. There are many ways manufacturers fudge these numbers. The proper way to measure / publish sensitivity is by listing the speaker's sensitivity as measured anechoically.

As measured at the NRC, the Energy RC10's anechoic sensitivity is 85.5dB. The Sierra-2's sensitivity is 86dB (anechoic). If you are OK with the output levels of your RC10 with your current amp, you will be fine with the Sierra-2 as well, (Sierra-2 actually have slightly higher sensitivity)

Here is a link to the RC10's true sensitivity measurements:

http://www.soundstagenetwork.com/measurements/energy_rc_10/

Hope this helps!

Thanks Dave! Very helpful information.
Jamus