Is bypassing the balance control possible?

[timindq]

I'm curious if it's possible to bypass the balance control on my recently finished Moreplay. And if so, how exactly to do it?

The reason I'm asking is, I'm considering running the Moreplay as a balanced unit in mono. 

[Paul Joppa]

It's certainly possible to bypass the balance control. However, I don't understand exactly what you mean by balanced unit in mono. I ask because the term "balanced" is widely mis-interpreted, and has lost much of its meaning.

[timindq]

Thanks for the reply. By balanced I mean installing XLR input and output connectors and feeding the Moreplay a signal from a balanced unit. Each tube will amplify equal signals with opposite polarity, thus a balanced mono preamp.

Is this any nuttier than installing coke-can-sized capacitors?

[Doc B.]

You are talking about a differential or push-pull preamp where the signal is split across two tubes with polarity flipped on one. Balanced is about the connection between pieces of gear, balancing the impedance from signal hot and signal cold relative to ground. That is why we are asking the question.

The only benefit I see to push pull is greater output voltage swing, useful in power amps. I don't see what advantage there would be in a line level device, and crossover distortion could create a sonic disadvantage relative to a single ended circuit.

[timindq]

You are talking about a differential or push-pull preamp where the signal is split across two tubes with polarity flipped on one. Balanced is about the connection between pieces of gear, balancing the impedance from signal hot and signal cold relative to ground. That is why we are asking the question.

The only benefit I see to push pull is greater output voltage swing, useful in power amps. I don't see what advantage there would be in a line level device, and crossover distortion could create a sonic disadvantage relative to a single ended circuit.

Thanks. Yes, that's what I'm asking. While it sounds like it's doable, it also sounds like it could, as you say, "create a sonic disadvantage." Bummer, as the unit sounds fantastic and I'd not want to ruin that.

[Paul Birkeland]

If you want balanced inputs and outputs, the BeePre is setup to accommodate this.

[timindq]

If you want balanced inputs and outputs, the BeePre is setup to accommodate this.

Thanks for the suggestion. Both my source and amp are fully balanced units, so I was thinking of building a balanced line level pre (two Moreplays) for less than $1K. The balanced BeePre is twice the price, if I understand the options. I will probably enjoy the Moreplay in its current configuration for a while before considering a BeePree.

I must say, the speed at which you all respond to questions is fantastic. Thanks.

[Doc B.]

As PB mentions, the BeePre2 can be configured with balanced inputs and outputs. But do keep in mind that the amplification stage of the BeePre2 is still single ended.

Bear in mind also that your two Moreplay setup will require the added expense of a balanced volume control as well as reconfiguring the input and output connectors to accomodate your balanced connections.

[Paul Birkeland]

Also for what it's worth, we have built and evaluated a fair number of balanced circuits over the years, and they tend to get met with a shoulder shrug in terms of our overall impressions.

[timindq]

As PB mentions, the BeePre2 can be configured with balanced inputs and outputs. But do keep in mind that the amplification stage of the BeePre2 is still single ended.

Understood.

Bear in mind also that your two Moreplay setup will require the added expense of a balanced volume control as well as reconfiguring the input and output connectors to accomodate your balanced connections.

While building the Moreplay I came across a pair of both input, and output XLR connectors in one of my boxes of miscellaneous parts. That's what gave me the idea for the balanced Moreplay. The idea is going on a shelf for now.

Also for what it's worth, we have built and evaluated a fair number of balanced circuits over the years, and they tend to get met with a shoulder shrug in terms of our overall impressions.

Interesting. Prior to inserting the Moreplay I was running my source, with volume control,  directly into my amp. Both pieces use differential balanced circuits. The source has single ended outputs which are feeding the Moreplay. The amp only has XLR inputs, so I fabricated a proper cable to get the signal to the amp. I was thinking of keeping the signal balanced throughout.