Balanced option for Fet Valve?

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Mike-48

Balanced option for Fet Valve?
« on: 11 Jul 2014, 03:24 pm »
Would balanced inputs be available for the Fet Valve series, as an option?  They would give better compatibility with the rest of my system. Thanks.

avahifi

Re: Balanced option for Fet Valve?
« Reply #1 on: 11 Jul 2014, 04:12 pm »
The problem with providing balanced inputs is that this requires either a matching transformer or an additional active circuit at the input of the amplifier and neither of these will do anything good for the music signal.

The only honest way to do balanced line performance is to build each piece of equipment in the audio chain with four discrete audio channels, plus left, minus left, plus right, and minus right, combining the signal at the speakers.  This will slightly reduce noise pickup if the equipment is used in an electrically noisy environment such as a live stage or mixing studio chock fulla electronics and cables. This issue does not apply in a normal home audio system.  Of course doing balanced line the right way requires double the number of active channels as with a normal two channel system and thus essentially doubles the cost for no useful purpose in a home system.  Doing it the quick and dirty way with two channel internal circuits and combining and separating out four separate channels to use those nifty cannon connections is worse then useless as the extra circuits just add distortion.

"Balanced line" is just more audiophlake foo-foo dust in most cases and always increases the cost.

You may think it sounds better, but actually since balanced line operation adds 6dB to the sound level, it will, all things being equal, sound louder, and everyone knows louder is better.

If your object is an awesome two channel music experience, then just go for great two channel equipment, not useless add ons.

Frank Van Alstine




Mike-48

Re: Balanced option for Fet Valve?
« Reply #2 on: 11 Jul 2014, 08:29 pm »
Right, I read that last time you posted it. I have a mixture of pro and consumer devices, and some doesn't have unbalanced outs. I'll look elsewhere.

JerryM

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Re: Balanced option for Fet Valve?
« Reply #3 on: 11 Jul 2014, 10:07 pm »


Blue Jeans Cable will make these for you if you tell them your pin out specs. Otherwise, they are available many other places, from Rat Shack to Guitar Center.

Have fun,

Jerry

Mike-48

Re: Balanced option for Fet Valve?
« Reply #4 on: 11 Jul 2014, 10:40 pm »
Thanks, Jerry. I appreciate your posting, but it's unlikely I'll use such adapters.

JerryM

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Re: Balanced option for Fet Valve?
« Reply #5 on: 12 Jul 2014, 01:01 am »
Frank briefly visited the fully balanced system pool some years ago. It seems to have led to some great new circuit designs. Check out this thread: http://www.audiocircle.com/index.php?topic=54139.msg483007#msg483007 

While these pieces are not currently available, it gives one a good idea of the implementation possibilities of a fully balanced system.

Have fun,

Jerry

Mike-48

Re: Balanced option for Fet Valve?
« Reply #6 on: 21 Jul 2014, 06:18 pm »
Frank,

What would be involved in getting a reasonably transparent connection using one of the two methods you mentioned? Would it be feasible economically for AVA to sell that as an option or accessory?  I have not been pleased with simple cable adapters.

I realize it's silly from your viewpoint, but I can't be the only one who is using some pro gear without RCA outputs. I'm eager to try your amp, but not eager to replace the upstream equipment in order to do so.

avahifi

Re: Balanced option for Fet Valve?
« Reply #7 on: 21 Jul 2014, 06:46 pm »
Supporting so called audiophile demand for balanced line inputs we ordered one production run of big amplifeir chassis with the sheet metal redone to accept XLR inputs as well as RCA jacks.  We also offered an internal stereo  "combining board"" to turn the balanced line in to single ended that the active amplifier circuits could use.  It was a $300 option.

The result was zero sales of this option.  We eliminated this from the next run of chassis as it made the back panel slightly less stiff and had been useless.

Frank


paul79

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Re: Balanced option for Fet Valve?
« Reply #8 on: 21 Jul 2014, 06:51 pm »
If your stuck with a balanced source, I'd suggest using a very high quality signal transformer to convert balanced to unbalanced. I wouldn't use a XLR to RCA cable.

Problem here is, in order to do this transparently (and yes, it can be done with great results), it takes a damn expensive transformer to pull off, and your source needs to have plenty of drive current. PM me if you want to go this route. Be happy to help.

Mike-48

Re: Balanced option for Fet Valve?
« Reply #9 on: 21 Jul 2014, 07:50 pm »
The result was zero sales of this option.

Sounds like it's not coming back any time soon. If things change, please let me know.

Mike

avahifi

Re: Balanced option for Fet Valve?
« Reply #10 on: 21 Jul 2014, 08:12 pm »
Remember that balanced line was designed for PA equipment where noise pickup in a live stage environment or mixing room full of equipment was an issue.

This is not an issue with home audio equipment.  Since balanced line makes everything 6 dB louder, that is what you are hearing, there is no way it makes thing better unless you want to go with four independent channels all the way from the source to your speakers, and that doubles the cost of the system.

We just are not going to do that.  Transformer coupled?  Now you are telling me that miles of tiny thinner then hairs wires in your signal path is great, while 6 feet of 14 gauge power cord or 3 feet of standard shielded interconnect cables are bad.  Throw in a bunch of exotic expensive fuses too while you are at it.

Lunacy abounds!

Frank Van Alstine

Mike-48

Re: Balanced option for Fet Valve?
« Reply #11 on: 21 Jul 2014, 08:28 pm »
It makes things better to me not because it's louder, but because I own it already. It is expensive to turn over gear, and one is never sure of finding something one likes as well. That's the start and the end of it.

I don't use special fuses, I don't use fancy power cords, and I buy my cables from Blue Jeans or make them myself.

RDavidson

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Re: Balanced option for Fet Valve?
« Reply #12 on: 21 Jul 2014, 09:40 pm »
Saying that the design/build/use of fully balanced electronics has no use in home audio is lunacy......unless your listening environment and gear is shielded. If anything, a fully balanced system may be more useful. Modern homes are becoming more and more loaded with interference from all the various electronics we now use.

Devil Doc

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Re: Balanced option for Fet Valve?
« Reply #13 on: 21 Jul 2014, 10:30 pm »
Perhaps, in order to take you seriously, you might wish to share your engineering credentials with us.

Doc

paul79

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Re: Balanced option for Fet Valve?
« Reply #14 on: 21 Jul 2014, 10:34 pm »
It makes things better to me not because it's louder, but because I own it already. It is expensive to turn over gear, and one is never sure of finding something one likes as well. That's the start and the end of it.

I don't use special fuses, I don't use fancy power cords, and I buy my cables from Blue Jeans or make them myself.

Right.. You like the Preamp you have, even though it Is balanced. This is why I recommended using the signal transformer as a balanced to unbalanced converter. There really is no better way to do this without ruining the sound.

RDavidson

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Re: Balanced option for Fet Valve?
« Reply #15 on: 22 Jul 2014, 03:56 am »
Perhaps, in order to take you seriously, you might wish to share your engineering credentials with us.

Doc

Oh, here we go again......pulling out the "If you're not an EE then you can't possibly know anything" card. One doesn't need to be an EE to read. :duh:
A fully balanced system has the ability to reject RFI and EMI. We all know that. Frank isn't disputing this either, but he disputes its use in home audio.
Maybe before things such as cell phones and wireless internet and fluorescent light bulbs became common virtually everywhere, I would've generally agreed with Frank. But the fact is, modern homes have an abundance of all these things, in addition to all the other various electronics, household appliances, as well as external interference sources that have existed for decades. If anything, our households' airwaves and electric lines are much more polluted than ever before.
You truly believe 100%, in all situations (short of a home PA system), that fully balanced circuits have no place in today's home audio? Lunacy I say.
« Last Edit: 22 Jul 2014, 02:03 pm by RDavidson »

avahifi

Re: Balanced option for Fet Valve?
« Reply #16 on: 22 Jul 2014, 02:16 pm »
I have no serious objections to a true "fully balanced" audio setup.  This will cancel any hum pickup and common mode distortion if there is enough in the circuits to worry about.

However a fully balanced setup requires four separate audio channels from source to speakers and essentially doubles the system price.

Balanced line with normal two channel circuits simply slaps either transformer or active circuits ahead and after the internal two channel circuits and I suspect that adding a bunch of additional circuits just to use balanced line interconnects is not a great way to improve your system, especially since this won't do anything about common mode distortion, just reduce noise maybe and add lots of converter circuit potential distortion sources.

If you have to share a single ended device with an already owned two channel unit using balanced line connections, just use one of the adaptor cables mentioned above.  Don't waste money adding to the complexity and distortion sources.

Frank Van Alstine