How to Improve Gain for RCA on Preamp. Can it be done?


I own a Schiit Freya+ which I use as a preamp to my active speakers.  I use the balanced XLR from my Freya+ to my actives (which have balanced XLR).

 The Freya+ has XLR inputs and RCA inputs but I have noticed a large difference in gain between the two. Specifically, I have looked at the following two scenarios:

A) source > balanced XLR in Freya+ > balanced XLR out > actives
B) source > RCA in Freya+ > balanced XLR out > actives

I observe a large difference in gain between (A) and (B) even when using the tube stage of the Freya+ (I almost always use the tube stage as it sounds the best and gives best gain).

For source, I have used my ADI-2 DAC FS which has both XLR and RCA out.  

The problem comes with my TT.  When I connect the phono stage by RCA to the Freya+, I have to turn the Freya+ all the way nearly to the limit to get satisfactory dB.  But directly connecting my phono stage to the actives (which also support RCA) gives excellent dB. 

The problem is I am purchasing new actives (Genelec 8351B) which support XLR but not RCA.  Therefore, my question is as follows:

Is there a way to improve gain on a preamp using RCA?  Is this problem that I am experiencing specific to the Freya+ or is this a general loss of gain (I am guessing 15 dB) that always accompanies RCA.  Are there preamps that would mitigate this?  I am willing to buy another preamp if so.   Let's say 3K for a new preamp as a round number.

hemtt3345

Always like this with RCA vs XLR. Technically, gain is the amount by which the input signal is multiplied. Gain is always fixed. Gain is fixed in amps, gain is fixed in preamps. You do not change gain other than by redesigning or modifying the amplifier stage within the component. 

What you are seeing is not gain. It is simply different input voltages. XLR always because of he way they are wired result in greater input voltage than RCA. 

Next thing to understand, the volume control is nothing to do with power or gain. All that control does is attenuate the input signal. What you are seeing is nothing more than the input from your turntable does not need to be attenuated very much to produce a lot of sound output. Your other components have higher voltage outputs and need to be attenuated more. I know this is pretty much the opposite of what everyone thinks so stop and let this sink in a while.

If you understand all this then you will realize there is nothing going on here but convenience. It simply is inconvenient to have to crank the volume knob a lot between components. That is all that it is. 

Probably your best option to avoid this is to look for either a higher output cartridge, or higher output phono stage, or both. Pay attention to cartridge output in mV, and phono stage gain, and especially to how many mV input it takes to reach 3V output. Because that is what you want, a lot of input voltage coming into your preamp.

Thanks for the help.

I am using a MM cartridge. My TT connects to a 90’s luxman integrated receiver with phono stage (not bad actually) but I could not for the life of me find the phono output (or figure it out). This is the closest I could find ...

Phono MM (5 mV Input Shorted) : 82 dB

What phono stage output should I be striving for?

"...Is there a way to improve gain on a preamp using RCA? ..."

 

Use the XLRs. Use RCA to XLR adapters from your TT into your pre.. 

Even with an XLR adaptor it will remain unbalanced and I believe voltage remains the same? 

The Sanders preamp will mitigate attenuation mismatches. Each input can be set to equal the others. Just keep it powered up because it does not write to eproms.

OR   

Get a phono pre that is adjustable. Or get a higher output cart.

 

Chuckie can keep his inconvenience.

"...Even with an XLR adaptor it will remain unbalanced and I believe voltage remains the same?..."

On my Big Mac, the output of the XLRs was twice the RCA outputs. It didn't matter that you adapted it to RCAs. 

 

I am using a MM cartridge. My TT connects to a 90’s luxman integrated receiver with phono stage (not bad actually) but I could not for the life of me find the phono output (or figure it out). This is the closest I could find ...

Phono MM (5 mV Input Shorted) : 82 dB

What phono stage output should I be striving for?

Okay, thanks, it helps a lot to know this is a card in an integrated amp. The "specs" don't help at all. But knowing it is a card helps a lot.

What you should do is look for a phono stage. You want one with a lot of gain. It will help to know the output of your current MM cart but you probably just want something with at least 50dB and even better 60dB gain. 

Gain is the amount by which the input voltage is amplified. Nobody likes math but if you can handle a little this will walk you through exactly how to find the right phono stage for your cartridge, at least in terms of gain. Rest assured just about any decent standalone phono stage will sound a whole hell of a lot better than what you have, even if only a hundred bucks or so. (The card that is in there now probably has $1 worth of parts on it, if that.) 

 

Thanks again!  I agree it's time to get a real dedicated phono stage.

 But just to let you know, I did try a highly recommended phono stage for a couple of hundred bucks and it was no where - I mean no where - as good as my Luxman.

I remember getting my first "highly rated" phono-stage at that price point long ago. It was truly terrible. Unfortunately phono-stages are not good at that price point. Typically they are only ok at ten times that. I would save up and then buy used. I would think Audio Research, Conrad Johnson, of course Luxman makes one that is not very expensive.

Always like this with RCA vs XLR. Technically, gain is the amount by which the input signal is multiplied. Gain is always fixed. Gain is fixed in amps, gain is fixed in preamps. You do not change gain other than by redesigning or modifying the amplifier stage within the component.

What you are seeing is not gain. It is simply different input voltages. XLR always because of he way they are wired result in greater input voltage than RCA.

@millercarbon Just so you know, this isn’t how its supposed to work. In a balanced system, the signal is not generated with respect to ground; ground is independent of the signal. So the RCA and XLR outputs should be the same voltage!

Think of a phono cartridge, which is a balanced source. Its output does not change if you run it balanced or single ended. The ground is the tonearm tube; its independent of the signal. Think of an output transformer, whose secondary can drive either single-ended (with one side at ground) or balanced (neither side at ground; ground is merely chassis with no other connection to the transformer). The output voltage is the same in either case.

When you see the gain difference as described, what is happening is that the inverting and non-inverting aspects of the balanced line are generated with respect to ground rather than each other. IOW, each is a single-ended output, with one out of phase with the other. This type of connection does not support the balanced line standard, since the ground connection is essential for its operation to complete the circuit.

So its not ’always like this’ as you say, its just like that if the equipment isn’t supporting the standard.

 

 

Is there a way to improve gain on a preamp using RCA?

Yes, a transformer.

https://www.jensen-transformers.com/

Arfffff ... Another plagiarising millercarbon cut n paste post goes wrong 

Another plagiarising millercarbon cut n paste post goes wrong 

@tsushima1 

There are several ways to interpret your comment; just so you know, Atma-Sphere built the first balanced line preamps offered to home audio back in 1989. We got a patent on the technique we used since we didn't use an output transformer and the preamp was all-tube. At the time it didn't occur to not support the standard; as others entered the field we were dismayed to see that very few supported the standard- to this day.