If you should decide not to modify the main amplifier:
Do you know whether the balanced preamplifier output behaves as a floating voltage source (like a transformer-coupled output usually does) or like two voltage sources to ground in antiphase? That determines whether you should or shouldn't ground the negative preamplifier output when you connect it to an unbalanced input.
Do you know whether the balanced preamplifier output behaves as a floating voltage source (like a transformer-coupled output usually does) or like two voltage sources to ground in antiphase? That determines whether you should or shouldn't ground the negative preamplifier output when you connect it to an unbalanced input.
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Is this the LS5-III?
Leave the VS55 alone and sell it. Get a VT100 MkIII instead.
You do know you'll need the ARC BL-2 to drive SE lines into the balanced only input for the LS5?
https://www.arcdb.ws/model/LS5
Good luck getting a BL-2 though...
https://www.hifishark.com/search?q=audio+research+bl-2
BTW, does the factory provide a teflon cap upgrade for the LS5?
Redesigning the ARC components is a crapshoot and you'll blow the residual value. How about getting a DIY A5 or A2 instead? I think the Babelfish amps have balanced inputs, huh?
And adding stuff between the ARC components is also a big crapshoot. Just my two cents. It's not like the DIYAudio clone amps where everyone can be trusted, ARC stuff was not meant to be modified.
If anything, see if you can get schematics for the BL-2.
https://www.ultimateservicemanuals....e-schematics-operation-manuals-390-pdf-on-dvd
Have fun.
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It's a ground lift switch. With the switch closed, the shield is continuous, but you can get ground loops. With the switch open, you can't get ground loops, but the shield is interrupted. Leave it closed unless you get hum, then listen if opening it improves that.
I thought I would be able to connect SE with a simple adapter. That's what other's reported doing.
The MKIII version of the LS5 included a switch to use in conjunction with an adapter. Looking at the schematic (attached), I think it just shorts the inverted half to the signal to ground?
Ignore @tonyEE he has passionate opinions but rarely reads the whole thread, as his suggested piece of equipment is the wrong direction for your application. (The BL-2 is SE to BAL…) Changing power amps may be interesting, but doesn’t address the question at hand.
🙂
Yes, you can go from your balanced output preamp to a SE input power amp with either just a cable, where the negative phase is grounded, or with a transformer, where the differential signal is maintained for the preamp, keeping everything as happy as possible for the respective equipment.
Connecting at the end would be ideal. 95% of the reason for balanced/differential is to have the noise and hum rejection of the balanced cabling, enabling long runs to be noise free. (Also why Pro equipment has higher levels than consumer, but that’s for a different day…) Keeping it balanced as long as possible is beneficial.
The LS5mkIII shows a switch for BAL or SE on the input selector, and yes, it is grounding the negative phase input during SE.
🙂
Yes, you can go from your balanced output preamp to a SE input power amp with either just a cable, where the negative phase is grounded, or with a transformer, where the differential signal is maintained for the preamp, keeping everything as happy as possible for the respective equipment.
Connecting at the end would be ideal. 95% of the reason for balanced/differential is to have the noise and hum rejection of the balanced cabling, enabling long runs to be noise free. (Also why Pro equipment has higher levels than consumer, but that’s for a different day…) Keeping it balanced as long as possible is beneficial.
The LS5mkIII shows a switch for BAL or SE on the input selector, and yes, it is grounding the negative phase input during SE.
Woah... I read the entire threads.... I'm sort of retired, remember?
My take is to follow the design of the BA-2, I posted the schematics, for the input side.
Then simply upgrade the amp to the VT100-III.
The LS5-III was one of the best sounding preamps from ARC. I don't know that I would dare change it or even put some DIY interface between it and the amp.
Ay, Jim... I do read the threads.... if you read my post... hmpfrr... you will see that ARC specifies using the BA-2 to provide SE input capability for the LS5. See here... there is indeed a gain control in the front panel, but this was quite common in all ARC preamps until about 20 years ago or so..
https://audioresearch.com/wp-content/uploads/2021/06/LS5_Manual.pdf
Maybe this time, YOU didn't read through my post, huh, huh?
Anyhow, the VT100-III and VT200-II are some of the best ARC amps made. Up there with the D70-II ( I got one ) and the D120 ( I wish I had one ). Those VT amps will be an outstanding match with the LS5-III. I've heard the combination.
My take is to follow the design of the BA-2, I posted the schematics, for the input side.
Then simply upgrade the amp to the VT100-III.
The LS5-III was one of the best sounding preamps from ARC. I don't know that I would dare change it or even put some DIY interface between it and the amp.
Ay, Jim... I do read the threads.... if you read my post... hmpfrr... you will see that ARC specifies using the BA-2 to provide SE input capability for the LS5. See here... there is indeed a gain control in the front panel, but this was quite common in all ARC preamps until about 20 years ago or so..
https://audioresearch.com/wp-content/uploads/2021/06/LS5_Manual.pdf
Maybe this time, YOU didn't read through my post, huh, huh?
Anyhow, the VT100-III and VT200-II are some of the best ARC amps made. Up there with the D70-II ( I got one ) and the D120 ( I wish I had one ). Those VT amps will be an outstanding match with the LS5-III. I've heard the combination.
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You likely can, but, but... what's the point of getting the LS5-III ( is it the III? ) and then messing around with it?
My point is that I've listened to the LS-5III driving the VT100-III and VT200-II and they are an amazing ( magic indeed ) combination. I don't know that throwing away half of the balanced output in order to drive the SE amp will be as magic.
I've also heard the VS55 too...
or left open, see post #21.
In a professional context, a big advantage of differential connections is that you can make the equipment insensitive to ground loops when everything is connected according to AES-48. When you have two studios and an extra room with equipment with lots of connections between all of them and a lot of the equipment has protective earth, avoiding ground loops is pretty much impossible. (Of course this is all ancient history, most studios are almost completely digital nowadays.)
@tonyEE I know, I’m just teasing you.
Anyway, BL-2 is SE to BAL. (Schematic attached) @SoaDMTGguy wants to keep his balanced preamp balanced and connect to a SE input power amp. This is a perfect job for a transformer. The Preamp will see a differential load and operate in it’s perfect world, the power amp will see a SE input signal and be happy, and there is galvanic isolation between the two breaking any ground loops. Nice!
Anyway, BL-2 is SE to BAL. (Schematic attached) @SoaDMTGguy wants to keep his balanced preamp balanced and connect to a SE input power amp. This is a perfect job for a transformer. The Preamp will see a differential load and operate in it’s perfect world, the power amp will see a SE input signal and be happy, and there is galvanic isolation between the two breaking any ground loops. Nice!
Attachments
What kind/brand of transformer would you use?
It better be one hell of good transformer not to take away from those components. It's not just a matter of looking at schematics at this level...
Anyhow, good luck, I'm off to hifishark.com to look for prices on VT200 and VT100...
It better be one hell of good transformer not to take away from those components. It's not just a matter of looking at schematics at this level...
Anyhow, good luck, I'm off to hifishark.com to look for prices on VT200 and VT100...
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CineMag or Jensen. Probably a 1:1 quadfilar as if you need to step down (not knowing if the ARC preamps are at pro levels or not) you have the ability.
@6L6 I wasn't sure if the transformer would preserve the noise rejection. That's fantastic! I have to have crossover boxes inline anyway for my speakers, I could probably combine them with a transformer and run them at the end of the line.
@tonyEE I bought the LS5 because I already bought the SP10 and didn't like it (too many knobs). The LS5MkII is supposed to be the best line stage ARC made, short of maybe the reference stuff. If I like it, and if balanced connections do make a difference over adapters, I can work on converting my equipment to all-balanced. I currently have a D-70Mk2. I am getting the VS55 to move to an open design. My amp sits at the front of the room, centered between the speakers, and becomes the defect centerpiece. I want something that looks the part. Right now the only VS115 is $2,900, which is more than I want to spend "just" to get balanced connections. As I said before, if I do see it making a difference with my DAC (which is balanced) I'll prioritize upgrading.
@tonyEE I bought the LS5 because I already bought the SP10 and didn't like it (too many knobs). The LS5MkII is supposed to be the best line stage ARC made, short of maybe the reference stuff. If I like it, and if balanced connections do make a difference over adapters, I can work on converting my equipment to all-balanced. I currently have a D-70Mk2. I am getting the VS55 to move to an open design. My amp sits at the front of the room, centered between the speakers, and becomes the defect centerpiece. I want something that looks the part. Right now the only VS115 is $2,900, which is more than I want to spend "just" to get balanced connections. As I said before, if I do see it making a difference with my DAC (which is balanced) I'll prioritize upgrading.
https://www.jensen-transformers.com/wp-content/uploads/2014/08/jt-11p-1.pdf
Simplest solution as already suggested.
Preserves noise and even harmonics cancellations.
Practically no downside.
If you are not happy, just sell them on.
Plenty of takers.
Might be long delivery time though.
Cheers,
Patrick
Simplest solution as already suggested.
Preserves noise and even harmonics cancellations.
Practically no downside.
If you are not happy, just sell them on.
Plenty of takers.
Might be long delivery time though.
Cheers,
Patrick
Is there any reason I should build it into the amp vs. converting the line somewhere near the end?
https://www.parts-express.com/Jensen-JT-11P-1-Premium-Line-Input-Transformer-11-246-0103?quantity=1
They claim to have stock.
Lucky you.
I would put it inside the power amp.
But if you want to keep resale value, then add it in between.
Patrick
They claim to have stock.
Lucky you.
I would put it inside the power amp.
But if you want to keep resale value, then add it in between.
Patrick
Can I run an SE source through one of those Jensen transformers and have it come out as a balanced signal on the other side?