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Understanding Gain in the ARC Ref Phono 2 SE


On my ARC Ref Phono 2 SE, it has a high gain and low gain setting. I am having
to use the high gain setting for adequate volume output. The low gain is just
too quiet, even when I turn up my Rowland Synergy IIi volume all the way. Now, this was different on my Rowland Cadence where I could use the low gain settings on it and the volume would be just fine. Although the high gain setting in the ARC Ref Phono 2 SE is fine, I would like to use the low gain setting if at all possible as it optimizes the lowest electrical noisefloor.

So here is some info/technical data on my system:

Cart:

Dyna XV-1s:
Output 0.3 mV; resistive loading recommended > 30 ohms

Here was the typical settings I would have on the Rowland Cadence:

Low gain: 64 dB (high would be 74dB). Cart loading ranges from 30-400 ohms


Here is the ARC Ref Phono 2 SE: (I run SE from tonearm to phono pre, balanced out of phono pre)

Gain: 51 dB low gain, 74 dB high gain (BAL) ; 45dB low gain, 68 dB high gain
(SE)

Cart loading: 50-200 ohms

Output impedance: 400 ohm balanced out (recommended load 50K-100K ohm)

I'm guessing my volume in low gain on the ARC is due to running BAL (51dB)
compared to BAL on the Rowland Cadence at 64 dB. On to
something there?

Then I wonder despite the above if the pre amp specs may still play a role:

Rowland Synergy IIi

Input Impedance: BAL at 36K ohms or 600 ohms. This is switchable and default
is 36K ohms. Never tried the other lower ohm setting.

Output Impedance: Balanced at 80 ohms

Eventually if I purchased an ARC REf 5SE preamp, here are the ARC Ref 5SE preamp specs:

Input Impedance: 120K ohms balanced

Output Impedance: 600 ohms balanced; 20K ohm resistive load

So I'm guessing again its the difference in output in the BAL configuration low gain settings from the Cadence (64 dB) to the ARC low gain BAL (51dB). Any way to use the low gain setting in the ARC through my Rowland Synergy IIi to get adequate volume output without turning up the volume to maximum settings? Changing the input impedance of the Synergy to the lower ohm setting? Eventually would a new ARC Ref 5SE preamp help this?

Any input or advice would be appreciated as I would like to use the low gain setting in the ARC as I did in the Cadence.

philb7777
14 responses Add your response
jjrenman
279 posts
 
Thanks for the extensive info, always appreciated when trying to get to the bottom of an issue.

Have you listened to the noise floor in both low and high gain on the ARC? I checked the spec's and if I understand them they actually show less noise in the high gain mode. Probably because the design uses very low noise fet's on the high gain input.
actusreus
733 posts
 
The Cadence is a MC-only phono preamp, while it appears that the ARC can accommodate both MM and MC cartridges. So the low settings on each of the preamps are meant to be used with different types of cartridges. The low setting of 64 dB on the Cadence is meant to be used with higher output MC carts, while the high setting of 74 dB is meant for low output MC carts. The ARC's low setting of 45/51 dB is too low to provide enough gain for an MC cartridge (at least the ones I'm familiar with), but would certainly easily accommodate any MM cartridge out there. Your MC Dyna cartridge needs approximately 61 dB of gain so while the 64 dB with the Cadence was just about perfect, 45/51 dB with the ARC's low setting is not nearly enough, and that's why you have to use the high setting.

Members who are more knowledgeable than I are free to correct me, but input and output impedance do not really factor in as far as the volume level and gain are concerned.

Btw, congratulations on this candy piece of equipment as well as the cartridge.
desmokid
4 posts
 
It sounds better in high gain with medium and low output MC cartridges even if you can get by with low gain. It's nice and dynamic, powerful, and loses a lot of that power in low gain mode unless you are using a high output cartridge.

Since sounding rig.
almarg's avatar
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almarg
9,670 posts
 
Excellent points by the others.
I'm guessing my volume in low gain on the ARC is due to running BAL (51dB) compared to BAL on the Rowland Cadence at 64 dB. On to something there?
Yes. As ActusReus indicated, 51 db of phono stage gain is too little for use with a 0.3 mv cartridge, at least in most systems.

I see that your Synergy IIi provides adjustability of its overall gain for each of its inputs over a very wide +/- 20 db range, in 0.5 db increments. Have you experimented with different settings? If not, that is where I would start. Perhaps reducing it for the high gain setting of the phono stage, and increasing it for the low gain setting, and comparing both sonics and noise levels for various settings.

I would NOT suggest that you change the preamp's input impedance setting to 600 ohms. That is much too low a value for the phono stage to drive properly.

Regarding possible upgrade to a Ref 5se line stage, I have no particular knowledge of that preamp but my guess is that it would not help. Its maximum gain is 12 db balanced/6 db single-ended, which I doubt is enough for use with the low gain setting of your phono stage; its noise performance may not be any better or even as good as that of the Synergy; and the limiting factor with respect to system noise performance when a phono source is being used will generally tend to be noise that is generated or picked up where signal levels are lowest, i.e., in the phono stage and/or the phono cable.

Regards,
-- Al
philb7777 OP
401 posts
 
Thanks for the responses and info.

The noise floor in the high gain setting on the ARC is just slightly more noticeable than the low gain setting. This is not audible at the listening position, just next to the speaker.

What you are saying makes sense - gain is gain! I will try to increase the gain setting on the input in the Synergy and experiment.
gpgr4blu
1,078 posts
 
Philb7777
I have red 40 and ref phono 2 and use with dynavector xv1-s. high gain is the only way to go. My favorite loading is 500 ohms. But you may prefer others.
philb7777 OP
401 posts
 
Thanks Gpgr4blu!
sarcher30
596 posts
 
Sounds like the gain on the ARC is either too low or too high. You could use an outboard SUT to get a more appropriate gain. Maybe try a 10x SUT with your low gain setting.

Your Rowland phono stage may just have a lower noise floor in general.

Which phono stage do you prefer regardless of noise?
philb7777 OP
401 posts
 
I prefer the ARC over the Cadence in my system. The Cadence is fanstastic. Super quiet but with my system a tad on the dark side. The ARC give much better continuity to the soundstage and all the good tube- stuff. Plus much better dynamics and ambient retrieval of space and info. Imaging density slightly better with the Cadence, but imaging in the ARC more 'realistic' if that makes sense.

I'm keeping both, but using the Cadence around 10% of the time to the ARC 90% of the time. When I get a second arm and cart for my table, I can have active use of both.

Good to know others with low output carts are using high gain in the ARC.
dctom
103 posts
 
I have the ARC ref 2 and use it with a BAT 52se. I had a Benz with an output of 0.35 which was OK with the low gain (balanced output) 95 vol setting (140 max). Also a vDH cart which is even lower, this was again ok at 95-104 vol.

If I want to listen to loud rock say N Young or White stripes I used the high gain.
I have recently purchased two new carts with outputs of 0.5 and 0.55. These work perfectly with the ref 2 on low gain.

I prefer the low gain as the ref2 gives a sweeter more realistic sound and produces a better image/stage, when listening to jazz or classical.

I think this is a flaw in the ARC, as for me, it rules out very low output carts. Fortunately there are some excellent higher output devices now.

Having said all this I dug out a 30yr old FR 1 iii to try. It sounded superb on the low setting with an output of.14Mv. However I needed to turn the vol to 110.

I think the BAT helps being virtually silent, even at high volume settings.

I recently compared an Allnic 3000 to the ARC. I was surprised to observe the Allnic has a considerably lower noise floor and much greater gain. I guess this is due to it's use of step up trans formers, which add a bit of extra colour.

I am hoping to upgrade to the ref2 se which I believe is quieter.
philb7777 OP
401 posts
 
Dctom -

The Ref 2 SE is super quiet. At a volume turned up to a meter level of 40/60 on my Rowland Synergy IIi and the high gain setting noisefloor is only audible when placing your ear a few inches away from the tweeter/mid. In low gain, still silent at those volume levels. Being used to solid state, I was amazed at how quiet tubes can be. The SE upgrade is probably well worth it.

My next carts will be in the 0.5 mV levels so I can utilize the low gain settings in the Ref 2Se more.
dctom
103 posts
 
Philb7777

That is good to hear. I like the sound of the ref2 it is better than the Allnic so if
the ref2 se is a significant improvement then I will be pleased.
It is well worth using higher output (0.5mV or above) cartridges with the ref2.
number95
44 posts
 
I have Ref 2 SE and prefer so far its low gain setting with my current cartridge (a Transfiguration Phoenix, 0.4mv). Compared to high gain, low gain has considerably better tonal seperation, more refined soundstage and has more neutral and realistic presentation, it is more relaxed too. Soundstage and objects are thinner at high gain and less detailed highs (I use balanced output so 74db vs 51db). The pity with low gain is I need to increase volume level on Ref3 preamp considerably higher, even if I have not initially preferred to push volume on preamp and tried high gain on Ref2 SE, I always ended with switching to low gain. I am not quite sure if low gain is superior to high gain on Ref2 SE or 74db is too much gain for 0.4mv cartridge output. I am not decided yet but close to buy new flagship cartridge of Transfiguration (Proteus with 0.2 mv output) in this case there is no option but to use high gain stage of Ref2 SE. So if the current issue is due to too much gain on 0.4mv this should be corrected due to 0.2mv cartridge replacement. If high gain is inferior to low gain regardless of cartridge output, then I will look to get higher output mc cartridges as alternative (Clearaudio etc) or look for another phono preamp with better high gain.
tomic601's avatar
tomic601
12,841 posts
 

bumping…because I deeply miss almarg…wisdom, grace…..RIP

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