Opinions? Sunfire Amp- Voltage vs. Current out

I've had my Sunfire Cinema Grand 200 ~five for about 6 months now, vertically biamping my Aerius. Overall, I'm very happy with the sound, and they were a HUGE improvement over my old Adcom.

Originally, I was driving both the Stats and Woofers from the Voltage outs. Today, following Carver's recommendation, I decided to try powering the Stats from the Front Current outs. At first blush, I like the softer highs better with this configuration. However, I wonder if I'm sacrificing fidelity in some other facet, that will become apparent after extended listening.

For those of you driving your ML's with a Sunfire amp, just wondering what your opinions are re the Voltage vs. Current outs.

sleepysurf said:

I've had my Sunfire Cinema Grand 200 ~five for about 6 months now, vertically biamping my Aerius. Overall, I'm very happy with the sound, and they were a HUGE improvement over my old Adcom.

Originally, I was driving both the Stats and Woofers from the Voltage outs. Today, following Carver's recommendation, I decided to try powering the Stats from the Front Current outs. At first blush, I like the softer highs better with this configuration. However, I wonder if I'm sacrificing fidelity in some other facet, that will become apparent after extended listening.

For those of you driving your ML's with a Sunfire amp, just wondering what your opinions are re the Voltage vs. Current outs.

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I don't think you're sacrificing anything following Carver's recommendation. Their labs have shown that planar/ribbon speakers respond better with the current outs. That's how mine is and I honestly never looked back once I read that line in the user manual.

I'm using the current out from my Sunfire right now. I don't feel like there's any loss. My front amp is on order right now (VTL ST-150), and having auditioned the VTL prior to buying it and then putting the Sunfire in temporarily, I feel the smoother current out of the Sunfire is more pleasing to my ears and closer (though not nearly as close) to running tubes.

I am shoot gun bi-wiring with the voltage source. I find the current source is too smooth, like every note is being smeared together.

Just an update. After ~1 yr listening with my Sunfire amp "current" outputs feeding the Stats, and 9 months with my Benchmark DAC-1 in place of a pre, I decided to try the "voltage" outputs to the Stats again, just to compare. Wow! The highs are now MUCH cleaner (louder too), and better balanced with the woofer. No doubt the higher impedance of the "current" output effectively rolls off the highs a bit, yielding their "tube-like" sound. However, with my "server-source" Squeezebox 2 feeding the DAC-1, jitter is essentially eliminated, and the purer voltage outputs now give a cleaner sound. For those still using a Sunfire amp, who have since embraced digital lossless streaming, you owe it to yourself to revisit the current vs. voltage option.

I am new to Sunfire, if each channel has max power rating of 200w, then what is the power rating for the voltage and current outsource respectively? One member mentioned powering the woofer with the voltage and panel with the current from the same channel, I wonder, in this case, how is the power distributed dynamically and exactly what is the max power that is usable? To me, a 5-channel Sunfire with both current and voltage outsources is like a 7-channel amp? Theoretically, this just confuses me. Thanks.

The key is vertically bi-amping the Sunfire, where the Stat panels and Woofers EACH get 200 watts (actually MORE, if needed, with Carvers "down-tracking" power supply design). Here is the link to the (old, but useful) Sunfire Cinema Grand review that explains it in detail... http://www.vxm.com/21R.116.html

Works for me!

sleepysurf said:

Just an update. After ~1 yr listening with my Sunfire amp "current" outputs feeding the Stats, and 9 months with my Benchmark DAC-1 in place of a pre, I decided to try the "voltage" outputs to the Stats again, just to compare. Wow! The highs are now MUCH cleaner (louder too), and better balanced with the woofer. No doubt the higher impedance of the "current" output effectively rolls off the highs a bit, yielding their "tube-like" sound. However, with my "server-source" Squeezebox 2 feeding the DAC-1, jitter is essentially eliminated, and the purer voltage outputs now give a cleaner sound. For those still using a Sunfire amp, who have since embraced digital lossless streaming, you owe it to yourself to revisit the current vs. voltage option.

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Agreed, the Voltage source sounds much better than the Current source with its added resistance.

For those who don’t know, the Sunfire ‘Current’ source outputs is basically the same as Voltage + a 1 ohm resistor in series with the + line out.

That extra resistance tends to provide a gentle high-frequency roll-off that is often preferred by those who are new to ESL’s (or who love the tube sound).

I keep trying the Current out every couple of years, and while initially it has some appeal, it is just not as satisfying as the voltage source. And using the measuring rig, it definitely is not as accurate.

You are right that balance is indeed better with voltage source, partially because it skews the ‘tilt’ towards the woofer.

With very clean front-end sources, the cleaner highs of the voltage source are appreciated better.

For instance, in my center channel, I even wired an optional 1 ohm resistance in front of the ESL transformer because I had bypassed all passive crossover components, and some amps don’t like pure reactive loads. This resistance, when switched in, does introduce a FR dip at the high end. I did this primarily as a safeguard against amps that could not deal with direct driving a transformer, but these Sunfires have current to spare and drive the transformer with no problems and absolutely great fidelity.
I’ve been running it without resistance (i.e. voltage source) since I deployed it and love it.

I also rip all my audio to a server and use an upsampling PC based player (foobar2000) and pro-level audio cards to feed a Meridian front end. It is so much better than CD’s spun in a player (even a good one).

Glad to hear you are enjoying your Sunfire and ML combo. They work very well together.

The Sunfire Amps are one of the most versatile amps for HT or 2 Channel. You easily biamp for stereo use with a 5 or 7 channel amp. Just use an RCA interconnect to jump from one amp channel to another.

You can also quasi-biamp (for lack of a better phrase that is what I will call using both the current and voltage output simultaneously). By quasi-biamping you use one channel with the "current output" driving the panel and the "voltage output" driving the woofer. I do this with my HT system. The total power output is 220w per speaker for the Cinema Grand V Series II model. The older models are 200w per speaker.

I suppose you could quasi-biamp with this amp on Summits but I haven't tried it with mine. I mainly use my Sunfire amp for 5.1 HT driving Ascents/Aeons, Cinema and Scripts. Of course if you have the available amp channels then true biamping is the way to go.

If you look inside the amp you'll see there is only one additional component on the "current output" that isn't ther for the "voltage output" I don't know if that piece is a resistor or capacitor or what but it the difference between the two electronically isn't much.

Regardless, the Sunfire amps are a good match for MLs and give you some flexibility for biamping and/or a choice between 2 sonic signatures. Although, I prefer my tube amp for pure 2-channel music.

I've owned a Cinema Grand since '97 and paired it up to my ReQuests in '98...I've had them wired every way imaginable in a stereo setup and I always have gone to current for panels and voltage for woofers for the best sound.... no matter what the load on the Sunfire this amp has never let me down. I have had the recent fortune of expanding to a full ML system adding a Theater i and a couple of Scripts. To power them I added a new Sunfire Signature 400~7(400-8ohms, 800-4ohms, 1600-2ohms times 7 channels) in addition to my old Cinema Grand. I haven't received my Scripts yet cause they're on backorder, as soon as I do I'll let you know how the system sounds in its new setup. I'm pretty excited since I've had the other setup for so long now.

Dan

1 Ohm resistor = tone control

Craig said:

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If you look inside the amp you'll see there is only one additional component on the "current output" that isn't ther for the "voltage output" I don't know if that piece is a resistor or capacitor or what but it the difference between the two electronically isn't much.

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Craig, that component is a 1 Ohm resistor. That added impedance in series with the panel Crossover does two things:
1- it alters the high end frequency response by rolling it off.
2- It lowers overall SPL to the panel (if just wired to panel, otherwise whole speaker), tilting the balance to the woofer a bit

Combine 1 and 2 and you have a stronger bass, mid-bass and midrange vs highs. In some rooms, this is much better than bright highs. Maybe there are room reflections that cause issues and toning down the highs is exactly what you need.

Therefore, I never say it’s wrong to use either one. My only point is that Current source is sort of like a tone control. If that’s what you need, then great.

See the attached image for a measurement of a brand new (2006 vintage) SL3 panel with and without the 1 Ohm impedance added. Note the significant roll-off starting at around 5Khz.
The Teal trace is the straight panel, the blue and green traces are the panel with a 1 Ohm load in front of the Transformer (and no other crossover components).

I will have to second the voltage connection to the stats. I have a signature @ 425 X 5. I only connected the current - and originally had it that way for a year. One night - I switched it back. I think the diff was the stage depth -more impact. I don't know - I think I just liked it better. I'll keep it like that for several months - then flip it back again and see if my opinion changes... But - right now - I think the voltage to stats gives a cleaner - more open - more stage depth - more slam - type of sound.....

Wow... I have been using my Cinema Grand for years now with the current output to the panels and the voltage output to the woofers on both my rebuilt Sequel II's and a stock pair of Request. I still can't decide what speakers I like better. I have a really bad room for speakers. Since reading this post, I must try the voltage outputs on the panels. Thanks, everyone !!!!!