Bi-amping With "Y" Splitter: Any Impedance Problem?

[Ron Resnick]

If single ended is noisy, then try the transformer back at the preamp end.

The only thing the evil poltergeists in this room have been unable to attack with success is my noise level. Not to jinx anything, hopefully, but my system employs every noise inducing element possible:

-- different lengths of AC circuits (good for manufacturing ground loops)

-- different components on different AC circuits

-- Jadis amplifiers (prone for making hum problems, apparently)

-- mixing single ended and balanced components

-- mixing single ended interconnects and balanced interconnects with "Y" adapters

-- tube and solid-state amplifiers right next to each other (good for inducing EMI)

 

[DonH50]

I looked briefly at Lundahl; seems like a good company after a very quick look. Been in business a long time, some good technical info on the site, maybe the European version of Jensen? The SE-Differential converters on the pro audio page look reasonable. I did not dig into the datasheets; you might want to ask them (and Jensen) about your application since source and load impedances are on the high side.

One thing to double-check is XLR polarity; some reverse pins 2 (+) and 3 (-).

As for the REI amp, does the company have suggestions for driving from a SE source? The conventional schemes off-the-cuff are:

1. RCA shield to XLR pin 1 (ground/shield), RCA center to XLR pin 2, XLR pin 3 open;

2. RCA shield to XLR pin 1 (ground/shield), RCA center to XLR pin 2, XLR pin 3 to ground/shield;

3. RCA shield to XLR pin 1 (ground/shield), RCA center to XLR pin 2, XLR pin 3 to ground through a resistor equal to the source impedance (1k in your case, this helps maintain common-mode rejection);

4. Some recommend connecting RCA shield to XLR pin 3 so the XLR shield only goes to the chassis, or to the shield of a balanced cable, perhaps through a resistor;

5. RCA to an active (typically op-amp) or passive (transformer) SE to differential converter to the XLR.

The best connection is usually a converter, but many manufacturers have to deal with SE to differential (and/or balanced) conversion. What works best depends upon the amplifier's internal circuit, the input circuit and grounding scheme, so they should hopefully have suggestions. I only saw balanced from preamp to amp in their user manual, however.

 

[Ron Resnick]

Thank you for the brainstorming!

Single-ended into the REI is for my personal experimentation only, so no big deal either way. Right now I am using my in-wall balanced cables, so no solution needed because there is no problem to solve.

In two prior systems and now in my own system I have proven that the REI is a wonderful, synergistic match with Clarisys Audio loudspeakers. But I am a tube guy, so I like to play and experiment.

 

[Holmz]

The only thing the evil poltergeists in this room have been unable to attack with success is my noise level. Not to jinx anything, hopefully, but my system employs every noise inducing element possible:

-- different lengths of AC circuits (good for manufacturing ground loops)

-- different components on different AC circuits

-- Jadis amplifiers (prone for making hum problems, apparently)

-- mixing single ended and balanced components

-- mixing single ended interconnects and balanced interconnects with "Y" adapters

-- tube and solid-state amplifiers right next to each other (good for inducing EMI)

An occasional cob web, does not mean that the house is haunted.

I am a bit more pragmatic…
If there is a problem, only then it should be fixed.
If it is only a potential problem, then “A fix” could be fixing a non existent problem.

Neutrik, and others, have simple XLR to RCA adapters.
It is either the male or female…
https://www.neutrik.com/en/product/na2fpmf
That gets things going, and provides a basis from which to work.
It is @DonH50 version #2.

…
2. RCA shield to XLR pin 1 (ground/shield), RCA center to XLR pin 2, XLR pin 3 to ground/shield;
…

Or jump to the Jenson first.

If it was some traveling show, then having “all the fixes”, means that one does not have to trouble shoot it 10 minutes before the doors open. Which is usually achieved by having balanced connects everywhere.

There are certainly easier amplifiers to use for bi-anping, but I am not sure if there are many tube amps set up for making it easy??

 

[DasguteOhr]

The only thing the evil poltergeists in this room have been unable to attack with success is my noise level. Not to jinx anything, hopefully, but my system employs every noise inducing element possible:

-- different lengths of AC circuits (good for manufacturing ground loops)

-- different components on different AC circuits

-- Jadis amplifiers (prone for making hum problems, apparently)

-- mixing single ended and balanced components

-- mixing single ended interconnects and balanced interconnects with "Y" adapters

-- tube and solid-state amplifiers right next to each other (good for inducing EMI)

To find the source of the noise you have to proceed systematically. First step: get a short circuit plug (RCA) then only connect the power amp to the loudspeaker. Put the short circuit plug on the input of the power amp an switch on. No noise, good if you can still hear noise from the loudspeaker. Usually noisy tubes or a defect in the amp. If it's noise-free, connect the cable to the preamp. Disconnect all signal sources. Choose an input and plug the short circuit plug in there. Then switch it on. Noise-free, then test each signal source individually to find the culprit. Disconnect all unused devices from the main power during the test. Humming is 95% likely to be caused by different manufacturers' grounding and earthing concepts. Only a groundbreaking (RCA) transformer will help here.
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For rca to xlr the neutrik adapters are excellent

NA2M-D0B-TX

Miniatur Transformator Symmetrie Adapter, 3-poliger XLR Stecker - Cinch / Phono Buchse, schwarz kodiert

www.neutrik.de

 

[DaveC]

The Lara currently on audition is SE and balanced.

Jadis JPS2 is single-ended only.

The Jadis amps are single-ended only.


I would be perfectly happy with this scenario, but I have to check with Angus to see if that causes the REI a problem. The REI is true balanced from input to output, so I don't know if it will be happy with Pin 3 unused.


Thank you, but I won't be modifying any REIs.

Why did you choose a Jensen transformer for that purpose rather than a fancier, audiophile-beloved Lundahl?

Components are not single ended and balanced, but if the manufacturer uses separately buffered outputs that can be used at the same time then there you go... SE to Jadis and XLR to REI, each output running one amp only, no splitter.

 

[sparkie]

For our electrical engineer members: Does using a "Y" splitter on an interconnect cable to direct a pre-amp output signal to two different amplifiers for bi-amping cause any impedance problem?

Does having the dual amplifier loads derived from the same interconnect alter the source/load impedance seen by the input of each amplifier?

Thank you!

Yes it can especially if its with two different amp technologies (one tube and another solid state) and interconnect convention (balanced XLR vs unbalanced RCA).

If you are dealing with two unbalanced (RCA) input amps, you have to isolate their inputs by either using a resistor the size of the input impedance in series with the signal input, or signal transformers. If you don't need power isolation, then the isolation resistors could be the size of the preamp's load impedance times 2.

EDIT:
Looking at the Jardis amps online, they look like they are DC coupled so you will have to add the 200K resistor or use a .1uf capacitor when you use a transformer, otherwise the bias of the input stage will be effected.

Since you asked and even though you didn't need it, I decided to give you the solutions. Since the impedance of the Jardis is high, you might be able to use a Y split if you use a capacitor in series with the input of the Jardis.

 

[ihmeyers]

Yes it can especially if its with two different amp technologies (one tube and another solid state) and interconnect convention (balanced XLR vs unbalanced RCA).

If you are dealing with two unbalanced (RCA) input amps, you have to isolate their inputs by either using a resistor the size of the input impedance in series with the signal input, or signal transformers. If you don't need power isolation, then the isolation resistors could be the size of the preamp's load impedance times 2.

EDIT:
Looking at the Jardis amps online, they look like they are DC coupled so you will have to add the 200K resistor or use a .1uf capacitor when you use a transformer, otherwise the bias of the input stage will be effected.

Since you asked and even though you didn't need it, I decided to give you the solutions. Since the impedance of the Jardis is high, you might be able to use a Y split if you use a capacitor in series with the input of the Jardis.

Ron, thank you for starting a very interesting thread and thanks to everyone for responding.

We're there ever any suggestions about a very high quality XLR splitter to use? I have a Concert Fidelity CF080 that drives Merrill Element 116 amps and Wilson Sasha Vs. I just bought the matching Wilson LoKe subs that were delivered today. The CF preamp has a single XLR out (it has an RCA as well but you can't use both at the same time). The there a "splitter" I can use that won't degrade the sound? I had a cheap one lying around so I tried it for sh**ts and grins and it was terrible. Ruined the sound of the CF driving the Sashas. I've seen Synergistic makes a pair (for ~$600) but I think they use their less expensive cable to do it. I have no idea how it would sound. Would it make sense to see if Pine Tree Audio could come up with a custom solution. I love the preamp and can't but anything into the system that destroys that beautiful sound.

Thanks very much.

 

[shawnf]

Ron, thank you for starting a very interesting thread and thanks to everyone for responding.

We're there ever any suggestions about a very high quality XLR splitter to use? I have a Concert Fidelity CF080 that drives Merrill Element 116 amps and Wilson Sasha Vs. I just bought the matching Wilson LoKe subs that were delivered today. The CF preamp has a single XLR out (it has an RCA as well but you can't use both at the same time). The there a "splitter" I can use that won't degrade the sound? I had a cheap one lying around so I tried it for sh**ts and grins and it was terrible. Ruined the sound of the CF driving the Sashas. I've seen Synergistic makes a pair (for ~$600) but I think they use their less expensive cable to do it. I have no idea how it would sound. Would it make sense to see if Pine Tree Audio could come up with a custom solution. I love the preamp and can't but anything into the system that destroys that beautiful sound.

Thanks very much.

Would be interested to know too about high quality XLR splitters!

 

[Ron Resnick]

No, I never found anything comforting.

I wound up having Cardas make me custom RCA Ys.

I endorse the Pine Tree Audio idea!

 

[ihmeyers]

No, I never found anything comforting.

I wound up having Cardas make me custom RCA Ys.

I endorse the Pine Tree Audio idea!

Ron, if you don't mind me asking what did they charge? I know Synergistic sells XLR Y splitters through The Cable Company for $600 a pair.

At the end of the day, how much signal degradation was there using he Cardas splitter? As I mentioned above, just trying out the $20 splitter I had in my tool box was untenable. I ordered a $300 pair from Nerve Audio but I'm genuinely worried now that there will still be a significant reduction in sound quality. I guess I could always go another route on the preamp but the CF sounds so good in my system.

 

[Ron Resnick]

Ron, if you don't mind me asking what did they charge? I know Synergistic sells XLR Y splitters through The Cable Company for $600 a pair.

At the end of the day, how much signal degradation was there using he Cardas splitter? As I mentioned above, just trying out the $20 splitter I had in my tool box was untenable. I ordered a $300 pair from Nerve Audio but I'm genuinely worried now that there will still be a significant reduction in sound quality. I guess I could always go another route on the preamp but the CF sounds so good in my system.

I did not do a comparison before and after the Cardas Y. I liked the sound coming from the system which the Y adapter enabled. That was enough for me. So whatever degradation the Y, if any, occasioned it was more than offset by the resulting configuration. Honestly I'm just not more OCD about it than that.

 

[ihmeyers]

Based upon Ron's recommendation, I commissioned Jesse from Pine Tree Audio to build me a transformed based splitter. It will have two high quality Cinemag transformers and be wired with OCC wire. This design isolated the two power amps from each other and is probably as close to sonic neutral as I can get. I'm assuming at the end of the day this would be similar to having a preamp with two isolated XLR outputs instead of one. I didn't want to scrap the CF 080 so this is hopefully a high quality solution.

 

[christensenleif@msn.com]

If you like the solution, I´d think there´s a lot of better transformers to be bought
at least in SUT use their transformers are considered pretty mediocre,at best

 

[ihmeyers]

It's what Jesse from Pine Tree recommended. I didn't put any price constraints on him. Maybe for this specific application he thought it was the best fit.

 

[Ron Resnick]

Based upon Ron's recommendation, I commissioned Jesse from Pine Tree Audio to build me a transformed based splitter. It will have two high quality Cinemag transformers and be wired with OCC wire. This design isolated the two power amps from each other and is probably as close to sonic neutral as I can get. I'm assuming at the end of the day this would be similar to having a preamp with two isolated XLR outputs instead of one. I didn't want to scrap the CF 080 so this is hopefully a high quality solution.

What is your theory for the transformer-based splitter rather than a simple Y?

Of course with a simple Y we are changing the load impedance seen by the output of the pre-amplifier. Is your concern degradation of the sound quality as a result of the preamplifier output being unhappy with the greater load, and an anomalous tonal balance as a result?

Putting the question differently, am I underestimating the potential technical or sonic problems with a simple Y?

 

[ihmeyers]

My theory is I don't really have one, lol. I think a splitter could be fine but I am a little concerned about the isolation/interaction of a tube preamp and two Class D solid state amps. This is more expensive than SR Y splitter (or what Cardas likely would have charged) but not by much so I figured I'd give it a shot.

 

[Ron Resnick]

My theory is I don't really have one, lol. I think a splitter could be fine but I am a little concerned about the isolation/interaction of a tube preamp and two Class D solid state amps. This is more expensive than SR Y splitter (or what Cardas likely would have charged) but not by much so I figured I'd give it a shot.

That makes sense to me!

 

[Ron Resnick]

I think Jesse is a good guy, and he definitely tries to be flexible and accommodating and helpful.

 

[Holmz]

My theory is I don't really have one, lol. I think a splitter could be fine but I am a little concerned about the isolation/interaction of a tube preamp and two Class D solid state amps. This is more expensive than SR Y splitter (or what Cardas likely would have charged) but not by much so I figured I'd give it a shot.

Sort of depends on the input impedance of the amps.
If they are low, then the preamp needs to have the cojones to be able to drive them.
I thought that the 600 ohm spec sort of defined the cojones requirement?

I don’t really see how the quality of the Y can make a difference, as much as having a scoming that is driving the pair of cable with enough grunt. But it ill be interesting to see.

An alternative would be to pull the signal off of the speaker terminals and use that as the input to the sub(s).