Balanced output to SE RCA input - Harrison Labs?

[babadono]

ummmm...ok...I can try to explain. There are different types of balanced outputs. One type has a signal on the + output only and the - is just an equal impedance to ground. On this type it is ok to use the + signal and tie the - to the ground of the input of unbalanced inputs. The CMR of the connection will be lost (or very limited) but no harm will be done to the circuitry.The other type has signals on both the + and - outputs. Being there is a driven signal on the - it should not be tied to the unbalanced input circuit ground i.e. left floating. There are "fancy" derivations of this actively driven type of output, a transformer or cross coupled output that would allow the grounding of the - signal without damage. But these are rare. Best to use the safe connection if uncertain. Or use the recommended hook up specified by the manufacturer.

 

[babadono]

https://www.jensen-transformers.com/wp-content/uploads/2014/08/an003.pdf

this can help understanding....in fact check out all their app notes.

 

[john61ct]

THANK YOU! Will take time to process, integrate with what I got so far...

Meantime I may post more notes and discoveries as I collect them, anyone feel free to please correct me if I go astray.

Seems clear by now the Hlabs board is no "universal" panacea for ensuring safety in the Bal--> SE direction? That that idea is just not possible in passive adapters?

It might be useful for temporarily handling physical wiring pathways.

But at this point I'm thinking best approach might be, leave the native connectors as they are on the receiving sink component,

after research & testing do the grounding / floating conversion-wiring permanently in a custom patch cable and then

LABEL it well as BAL-->SE and "belonging to" the source driver component, designed for which receiving sink device.

 

[john61ct]

also Bill Whitlock 's Chapter 36 Grounding and Interfacing in AES' Handbook for Sound Engineers 5th Edition 2015

He dedicates this to Neil Muncy and apparently was also a strong advocate of "The Muncy Solution"

 

[PGRAHAM]

Here is an application variant on the subject of FMOD filters, with a question. I am not formally trained so I beg your indulgence.

The object is to insert a high-pass filter between an active balanced output at source and an active balanced input at load. Source is 112 ohms (56 + 56) output impedance; load is 44 k-ohms (22 k + 22 k) input impedance, each channel. The output device is 1/4" TRS and XLR paralleled, both used, and the input device is two amplifier inputs paralleled, both used. So I assume total load impedance is 11 k + 11 k, each channel, or something like that.

The XLR on the source device goes to the main system crossover system, while the 1/4" TRS goes to an auxiliary speaker system involving two lefts and two rights. All line-level interconnects in this installation are fully balanced.

Making no assumptions about whether a simpler method is possible while preserving system performance, the safe bet is a balun on both ends. This assures best results without doubts. The baluns are passive isolation transformers that will convert single-ended unbalanced to fully balanced, or other way 'round.

The configuration of the circuit is an ART DTI receiving balanced lines on 1/4" TRS, outputting to a pair of in-line FMOD high-pass via RCA jacks, then on to the RCA SE inputs on a second DTI outputting to balanced 1/4" TRS lines which go to the amps. This is two stereo baluns SE:SE back-to-back with a filter for each channel between. It's conceptually very simple; I hope my description of it is equally so!

The source device drives the main system whose 18" woofers have a design F3 at 35 Hz and roll-off on a Butterworth 3rd order alignment. There are powered subs in this system that go down to around 17 Hz but they do not enter into this as they are on separate signal paths. The low-frequency high-level mains signal will over-drive the auxiliary system speakers. This is the reason for the low-cut filters. The auxiliary system does not require output below the filter corner frequency, but will get this signal if not protected.

Speakers used in the auxiliary system are small high efficiency 2-way ported having a manufacturer specified F3 at 62 Hz. The FMOD at the advertised 70 Hz corner frequency and 2nd order roll-off will brick-wall the response. At present I am using a graphic equalizer with balanced ins and outs set up with a 24 dB spread between the 40 and 100 Hz sliders and 63 Hz on 0 dB. Although actually a shelving curve, this works great. But it's the only reason I have a graphic equalizer anywhere in this system, and it's noisy. So I'd like to find a better way, like a real cut-off filter.

So my question is, if there are folks out there who understand the theory better than I do, and I am certain there are, will you comment please? Is this gonna work? Seems elegant to me, but I could be missing something important.

 

[john61ct]

Best to start your own thread please, leave this one clean

I'm afraid your text is way above my paygrade to the point I have no idea what the new thread should be titled!!

 

[PGRAHAM]

My apologies. I thought it was on subject. Not my intention to high-jack the thread.

 

[john61ct]

No worries, I hope the experts here can sort you out, I know I can't yet untangle it!

 

[Waveform Fidelity]

Need a converter/adapter gadget

balanced output from XLR or Phoenix block to a single-ended RCA input

Quality transformers are pricey, ART Cleanbox Pro gets reco'd a lot, others?

Harrison Labs' universal Audio Patch Board, aka "Audio Parametric Patch Board XLR-RCA-1/4" Phone - Euro"

if I read it correctly, claims to accommodate any combination of XLR, 1/4” TRS jack, or Euro block connectors on the balanced side, and RCA or any of the above as unbalanced

in both directions! (?)

(Besides him being a dogmatic whacko, let's ignore that here)

I am skeptical that this board is safe to use (by a relative noob) going in the Bal-->SE direction? without input from the manufacturer of the balanced source device?

I would prefer to keep to the general Q, but my specific case here, is an output balanced pre- signal from a Phoenix block, to the RCA input of an SE-only power amp.

I want to keep the advantages of balanced wiring (long cables, noisy env) if possible.

You could try Bal to SE box made by Whirlwind -small easy to use.

If you have multiple outputs, then pick up a used TASCAM LA40 MKIII on ebay

 

[john61ct]

Yes but as stated this is a low budget system, I'm not looking to spend that sort of money unless necessary

so have more for more interesting and critical components.