Balanced input phono stages
Printed From: Graham Slee Hifi System Components
Category: DIY AUDIO
Forum Name: DIY Audio questions and answers
Forum Description: www.diy-audio-kits.com ... superb audio kits for experienced constructors
URL: https://www.hifisystemcomponents.com/forum/forum_posts.asp?TID=4568
Printed Date: 27 Mar 2026 at 2:15am
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Topic: Balanced input phono stages
Posted By: roger staton
Subject: Balanced input phono stages
Date Posted: 06 Sep 2018 at 11:13am
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Hello everyone, I although am new to the forum, and this is my first post, I am not new to music and the means to reproduce it - a good hifi system. I'm sure all of you must have an itch that they want to scratch and one of mine has been to own and use a phono stage with balanced inputs - ie XLR. Balanced input phono stages have been around for some time and are aimed only at low output MC cartridges. All MC cartridges are balanced by the nature of their design so a balanced input phono stage would seem to be a logical interface? Not everyone can easily use a balanced input phono stage (BIPS for short) as the changing of the cable from their tone arm is not easily achieved - either captive inside the turntable or not having a din plug that easily facilitates change over. These very facts have also prevented accurate reviewing in the hifi press - some reviewers making a half hearted attempt by using rca to xlr adaptors which do allow the full benefit of a BIPS to shine through. I have used a German Aqvox 2CI Mk II BIPS for 2 years now. It has MM and MC inputs - the former via unbalanced rca sockets. My cartridge collection is quite large with Lyra Kleos, VDH Frog, L*nn Arkiv, Denon 103R and Miyajima Mono Zero MC carts. and Grado Statement Master, Grado Reference, Musicmaker mkII and Soundsmith Zephir Mimic II LO MM cartridges. The heart of a phono stage for me is its MM stage which I use a lot not only with my MM carts but with a range of SUTs - Ear MC-4, K & K Audio and Fidelity Research FRT3 units. The musicality of the Aqvox's MM input is extremely musical to my ears imho. So having got that off my chest do any of you have any experience of BIPSs? Also extremly interested in Graham's opinion of BIPS and SUTs with MC carts into his MM stages. Thank's for reading. |
Replies:
Posted By: Graham Slee
Date Posted: 06 Sep 2018 at 11:37am
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Give one of ours a try before venturing too far into something which might just send you down a fruitless trail. Our loaner program (volunteer) coordinators are ready to help. It is over 25 years since I thought of doing a BIPS (as you abbreviate it), and I made one, and adapted the arm cable to suit. Measureably there was little difference, and OK, I quite liked the sound. Then, needing the turntable for its usual duties using a regular input I modified the arm cable back to what it was. I then made the input psuedo balanced based on a PMI application note (which basically shifted the balance nearer single-ended), and I could hear no difference at all. But it sounded fine, and I switched my listening to it. In fact I kept it like that until around 20 years ago - the point where I started commercial manufacture of my own designs. My opinion is that much more can be achieved without such faffing about. ------------- That none should be able to park up and enjoy the view without a smartphone and the knowledge in how to use apps |
Posted By: Graham Slee
Date Posted: 06 Sep 2018 at 1:36pm
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In fact here's the circuit recalled from memory...  You and anybody else are welcome to build it and give it a try, but I take no responsibility for any errors this diagram may contain. As I said above, it's recalled from memory. ------------- That none should be able to park up and enjoy the view without a smartphone and the knowledge in how to use apps |
Posted By: Graham Slee
Date Posted: 06 Sep 2018 at 1:39pm
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If a mod has time can this topic be moved to DIY questions and answers? ------------- That none should be able to park up and enjoy the view without a smartphone and the knowledge in how to use apps |
Posted By: roger staton
Date Posted: 06 Sep 2018 at 4:03pm
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The circuit in the Aqvox BIPS uses passive EQ with no capacitors in the signal path - so their service man Norman tells me. Of course if you choose the wrong type of MC cartridge the match will not be good and the qualities of BIPS will be largely lost. The MC cart.must have a low input impedance and inductance and a large - relatively - amount of current generation. The BIPS is a current amplification device not a voltage amplification device utilised by single ended MC cart phono stages. I never dis things until I've given them a good chance unless there is an obvious flaw in the logic; even then the sound might be magnificent! I am interested in the Accession MM stage and hope to hear it in my system at some future time. |
Posted By: Richardl60
Date Posted: 06 Sep 2018 at 4:47pm
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Welcome Roger. You have a good selection of equipment there. I would echo Graham's suggestion of trying the most suitable items on the loaner programme; if you are looking for versatility, you may find the Elevator compares well with your SUTs and perhaps from your comments and equipment the Accession MM may be the most suitable (I own both) - haven't tried the Accession MC though. I cannot comment on XLR to phono stage but have found them superior on my CD player; as Graham suggested the offer the shelf items may offer something of interest to you.
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Posted By: Fatmangolf
Date Posted: 06 Sep 2018 at 8:33pm
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Welcome Roger. Please give me a shout if you would like to try any of the HFC gear. I've used balanced gear including low level ribbon microphones (passive so low impedance sources) and concluded that its main benefit was in the balanced microphone cables not the gain stages where you need two identical stages or a very good balanced receiver stage. ------------- Jon Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC. |
Posted By: Graham Slee
Date Posted: 07 Sep 2018 at 3:05am
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Actually my circuit above would "allow the full benefit of a BIPS to shine through" (and using MM or MC - adjusted to suit). Dynavector patented I-V (current amplification) used for MC in the 70s/80s, but patents only last 20 years so the German manufacturer should be safe. I assume it's that being used here (doubled for balanced - one for each leg), because that doesn't work for all MC cartridges either. It also does part of the EQ, as it must, because of the loading it has on the cartridge due to it feeding a virtual earth, and that's why it doesn't work for all - it has to be "optimised" for a particular cartridge or the EQ is out - and Dynavector's invention obviously favoured Dynavector's cartridges once in production. However Norman could be talking about current-feedback op-amps which is a different kettle of fish. And yes, all transducers do seem to be balanced (I'm sure somebody will point me at one which isn't), or more correctly stated: floating. They can be used both ways, for example loudspeakers can be driven single ended or by bridging two amplifiers with one out of phase with the other. This could be called balanced (and is), but most would simply say bridged. Microphone capsules are floating but can be made to be either by the way they're wired; transformed; or preamplified. As for capacitor-phobia, I'm afraid I have to inform you and all readers that you can take out every physical capacitor from a circuit and still the signal will be subject to capacitance - which exists in all components. Yet another piece of marketing folklore which people claiming to be engineers have adopted (a bit like "pure class-A" and "zero negative feedback" - modern day paganism...) EQ simply doesn't work without capacitors and in the Dynavector patent a capacitor has to be in-line with the signal to replace the mid frequency RIAA knee. Passive EQ uses capacitors "across" the signal. How does this differ with them being in-line with the signal? Their effect can still be heard used "across" the signal! Some designers go to extremes to remove every capacitor they can. For example: DC output offset where an integrator (they call them "servos") is used to pull/push the output back to centre/zero - but an integrator uses a capacitor! Connecting an expensive cartridge directly (DC coupled) to an input comes at a price. Any DC offset, even a small amount, could gradually heat the fine wires - you know how fine they are? - and basically they are being used to bias the input DC level. Even if the coil windings survive they are effectively a solenoid with the armature being pushed "off-centre" by whichever way the DC input bias is flowing. If a speaker drive unit was pushed in or out to remain that way when the amp was switched on there'd be an outcry! But you can't see what's going on inside a £200 - £5,000 cartridge... ------------- That none should be able to park up and enjoy the view without a smartphone and the knowledge in how to use apps |
Posted By: roger staton
Date Posted: 08 Sep 2018 at 4:08pm
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Hello, I would like to try the Accession MM phono stage please if that could be arranged. regards Roger Staton
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Posted By: Fatmangolf
Date Posted: 08 Sep 2018 at 5:38pm
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No problem Roger. Please PM me (drop menu under my userid on the left) and we'll sort out the details. ------------- Jon Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC. |