I've been meaning to start a thread on mono vinyl playback for a while, but delay projects meant a lack of anything concrete to discuss. Still nothing concrete, but as a couple of members mentioned it would be useful to have somewhere to discuss this here we go.
I've got a fairly modest collection of mono vinyl (under 100 LPs) and I know that others have a lot more. I am saying this as the amount of effort to expend is related to the size of the collection. Having been collecting little bits an pieces for a couple of years, for my first semi-serious foray into mono playback I had an old ortofon MC10 converted by rotating the coils 45 degrees, making right channel lateral and left vertical. I had a good reason for this which I will explain another time but so far it works well. So I'll use this as the reference point to beat by other methods as time allows. Prior to this I had a stopgap preamplifier with a resistive combiner in for mono which worked but I was never happy with as it was a 5 min lash up to keep me running.
By my reckoning there are 4 main ways of getting to mono playback to discuss/experiment with.
1. Mono cartridge with no vertical output
2. Parallel strapped cartridge
3. series strapped cartridge
4. Summing in the preamp/phonostage/DSP
All are worthy of discussion and consideration, even if some end up being considered non optimal. I'll admit to not being a fan of parallel strapping even if that is how most if not all current mono MM cartridges are setup.
I'll add some more when I get time, but at least the thread is started. Oh and I fully expect there to be a stylus size/profile argument at some point 🙂
I've got a fairly modest collection of mono vinyl (under 100 LPs) and I know that others have a lot more. I am saying this as the amount of effort to expend is related to the size of the collection. Having been collecting little bits an pieces for a couple of years, for my first semi-serious foray into mono playback I had an old ortofon MC10 converted by rotating the coils 45 degrees, making right channel lateral and left vertical. I had a good reason for this which I will explain another time but so far it works well. So I'll use this as the reference point to beat by other methods as time allows. Prior to this I had a stopgap preamplifier with a resistive combiner in for mono which worked but I was never happy with as it was a 5 min lash up to keep me running.
By my reckoning there are 4 main ways of getting to mono playback to discuss/experiment with.
1. Mono cartridge with no vertical output
2. Parallel strapped cartridge
3. series strapped cartridge
4. Summing in the preamp/phonostage/DSP
All are worthy of discussion and consideration, even if some end up being considered non optimal. I'll admit to not being a fan of parallel strapping even if that is how most if not all current mono MM cartridges are setup.
I'll add some more when I get time, but at least the thread is started. Oh and I fully expect there to be a stylus size/profile argument at some point 🙂
Thanks for starting the thread. 
I listen to mono LPs with simple summing - or by some side channel rejection if I'm in a fancy mood.
Audio-Technica has a few mono carts that are stereo carts wired in different ways. What do you know about those?
I listen to mono LPs with simple summing - or by some side channel rejection if I'm in a fancy mood.
Audio-Technica has a few mono carts that are stereo carts wired in different ways. What do you know about those?
Ortofon has some mono cartridges as well, some based on SPU, and others perhaps a little more reasonably priced.
Denon's 102 LOMC was reputedly great for playing early microgroove mono LPs, but has been discontinued. It was reasonably priced.
^^The cartridges mentioned above are true mono cartridges, not ones modified from stereo.
The ne plus ultra might be the GE variable reluctance cartridge which came in mono and later stereo variants. I believe there were both microgroove and coarse groove styli for these cartridges. Various incarnations of these cartridges are popular with record collectors and I believe in a lot of cases styli are available.
Tube pre-amps like the Marantz Audio Consolette and McIntosh C-8 are expensive and sought after for mono playback. The Heathkit WA-P2 was shockingly decent sounding for the time and has flexible pre-RIAA EQ, as far as I know it's not insanely expensive. Any of these designs can be DIY'ed with some thought.
I have been approached in the past to design such a pre-amplifier, but if it happens it's well into the future... I am not sure whether there is sufficient interest to justify it.
Denon's 102 LOMC was reputedly great for playing early microgroove mono LPs, but has been discontinued. It was reasonably priced.
^^The cartridges mentioned above are true mono cartridges, not ones modified from stereo.
The ne plus ultra might be the GE variable reluctance cartridge which came in mono and later stereo variants. I believe there were both microgroove and coarse groove styli for these cartridges. Various incarnations of these cartridges are popular with record collectors and I believe in a lot of cases styli are available.
Tube pre-amps like the Marantz Audio Consolette and McIntosh C-8 are expensive and sought after for mono playback. The Heathkit WA-P2 was shockingly decent sounding for the time and has flexible pre-RIAA EQ, as far as I know it's not insanely expensive. Any of these designs can be DIY'ed with some thought.
I have been approached in the past to design such a pre-amplifier, but if it happens it's well into the future... I am not sure whether there is sufficient interest to justify it.
As I understand it, the original mono carts had no vertical compliance. That would cause damage to stereo LPs. That's why the modern ones are adapted from stereo carts.
Just curious: Is the mono playback system mono end-to-end? One speaker etc? Or do you intend to play back the mono signal through a stereo pair of loudspeakers?
That's true as far as I know, but should not a problem in a dedicated mono system which is what I thought we were talking about. Stereo compatibility brings with it the issues you wanted to avoid.
I personally would love to have a single speaker mono setup, but right now I cannot work out how to fit that into the house, unless I put in a centre channel. One day as I do feel dirty listening to mono on 2 speakers
When I inherited my KD-550 I was going to convert it to a dedicated mono turntable but I like it so much for stereo as well I am still not sure. I dream of an ortofon type A on a 12" tonearm for the authentic experience, but I don't have a turntable that will take it. A Garrard 301 would be lovely but I missed the time when they were affordable. So I'll just slum it and admire those who do it without compromise 🙂
I don't know much, other than I have yet to hear of anyone buying an ATmono3 or AT33 mono and regretting it. These both have dual coils, but laid flat so looks like a stereo cartridge to a phono stage. I suspect this is just due to the fact that AT wind their coils on a tiny ferrite bar so it made sense to be able to use the same production methods for stereo or mono. The AT mono3LP at around $150 is nearly in impulse buy territory if you can handle 1.2mV output.
I just added some mono capability to my stereo system. My stereo system consists of a highly modded L75 Lenco idler wheel turntable (equipped with stacked platter, 12 inch DIY wooden tonearm), a MC preamp (current input type, isolated power supply with LEDs and solar cells), a modified Pass ONO RIAA phono clone preamp, a valve line level preamp and two mono valve amps driving two large sized, high efficiency bass reflex speakers (15 inch woofer/ low midrange with 1.5 inch compression driver with horn). As a stereo cartridge, I'm currently using an AT 33 PTG II.
A couple of weeks ago I started collecting some mono LPs and was stunned about the sound quality even when played with the stereo system triggering the desire for a more dedicated system for these LPs.
I refurbished a second L75 turntable, installed a modified 9 inch tonearm with SME headshell connector I had lying around, build a dedicated MONO valve phono preamp with switchable EQ for mono records from the time before RIAA has become the worldwide standard for cutting LPs. I can switch the bass shelving for 800Hz, 500 Hz (=RIAA), 400 Hz and 250 Hz and the 'Highs' low pass independently from the bass shelving for -3dB frequencies of 1590Hz (100µs), 2122 Hz (75µs = RIAA), 2500 Hz, 3000 Hz and 8000 Hz (for usage with old shellacks). This preamp then connects to the line preamp of my stereo system by feeding the left and right input in parrallel. I like the mono reproduction over a pair of stereo loudspeakers better than only over one speaker. I also found it superior to only have one EQ network doing the job instead of feeding the stereo phono preamp with a mono signal as this resulted in a more diffus sound stage. This my be the result of not exactly identical EQ networks (even if I selected EQ components for no more than 0.1 dB difference between channels) in the phono pre.
Before deciding what cartridge(s) to use, I investigated what would be the best solution - the frustrating result is, that there is no best / one fits all. And it gets even more complicated if you also want to be able to play old shellacks.
These shellacks need a special stylus with 2.5 to 3 mill conical tip radius. The vinyl mono LPs before the mid 60's were cut with groove dimensions that are optimally played by a 1 mil stylus. Later records were cut on stereo capable cutting lathes with optimal stylus sizes of .5 to.7 mil stylus. The older mono LPs have a purely lateral groove that can be played with a stylus with almost no vertical compliance while later LPs (and this includes all mono reissues from end of 60's on which are numerous) need to be played with cartridges having at least some vertical compliance.
What does this mean now for my cartridge selection?
I decided to go for at least two different carts for mono LPs and one additional for older shellacks. For the old shellacks I was able to get my hands on a GE RPX mono cartridge (the second generation of the variable reluctance mono carts from GE). Replacement styli with 3 mil tip radius are still available. Tracking force is 6 to 8 grams. For the 'real' mono LPs I purchased a GE VT II mono cartridge (the next generation of GE's variable reluctance mono carts) Replacement styli are also still available with 0.7 and 1 mil diamond tips. Tracking force for this cart is 4 grams. Both of these carts are real mono cartridges only detecting lateral movements and give no signal for vertical excursions. They have only a very low vertical compliance and should never be used for stereo LPs or mono LPs cut on stereo capable lathes as they may damage grooves having a vertical component. For the later monos I currently use a series connected stereo MM system (a Tonar Diabolic). Due to the tonearm with SME headshells, changing the carts is quite easy and can be performed quickly. While this modern MM cart sounds really good on all vinyl mono LPs, the GE VRII gives an absolute stunning SQ with the early mono discs way superior to the mono converted MM stereo system.
Maybe I'll check one of the AT mono MC carts to see if they are better than the currently used MM system and if they come closer to the GE carts.
The largest surprise for me was the unexpected very good sound quality for these old discs and cartridges what made me a mono lover and collector.
A couple of weeks ago I started collecting some mono LPs and was stunned about the sound quality even when played with the stereo system triggering the desire for a more dedicated system for these LPs.
I refurbished a second L75 turntable, installed a modified 9 inch tonearm with SME headshell connector I had lying around, build a dedicated MONO valve phono preamp with switchable EQ for mono records from the time before RIAA has become the worldwide standard for cutting LPs. I can switch the bass shelving for 800Hz, 500 Hz (=RIAA), 400 Hz and 250 Hz and the 'Highs' low pass independently from the bass shelving for -3dB frequencies of 1590Hz (100µs), 2122 Hz (75µs = RIAA), 2500 Hz, 3000 Hz and 8000 Hz (for usage with old shellacks). This preamp then connects to the line preamp of my stereo system by feeding the left and right input in parrallel. I like the mono reproduction over a pair of stereo loudspeakers better than only over one speaker. I also found it superior to only have one EQ network doing the job instead of feeding the stereo phono preamp with a mono signal as this resulted in a more diffus sound stage. This my be the result of not exactly identical EQ networks (even if I selected EQ components for no more than 0.1 dB difference between channels) in the phono pre.
Before deciding what cartridge(s) to use, I investigated what would be the best solution - the frustrating result is, that there is no best / one fits all. And it gets even more complicated if you also want to be able to play old shellacks.
These shellacks need a special stylus with 2.5 to 3 mill conical tip radius. The vinyl mono LPs before the mid 60's were cut with groove dimensions that are optimally played by a 1 mil stylus. Later records were cut on stereo capable cutting lathes with optimal stylus sizes of .5 to.7 mil stylus. The older mono LPs have a purely lateral groove that can be played with a stylus with almost no vertical compliance while later LPs (and this includes all mono reissues from end of 60's on which are numerous) need to be played with cartridges having at least some vertical compliance.
What does this mean now for my cartridge selection?
I decided to go for at least two different carts for mono LPs and one additional for older shellacks. For the old shellacks I was able to get my hands on a GE RPX mono cartridge (the second generation of the variable reluctance mono carts from GE). Replacement styli with 3 mil tip radius are still available. Tracking force is 6 to 8 grams. For the 'real' mono LPs I purchased a GE VT II mono cartridge (the next generation of GE's variable reluctance mono carts) Replacement styli are also still available with 0.7 and 1 mil diamond tips. Tracking force for this cart is 4 grams. Both of these carts are real mono cartridges only detecting lateral movements and give no signal for vertical excursions. They have only a very low vertical compliance and should never be used for stereo LPs or mono LPs cut on stereo capable lathes as they may damage grooves having a vertical component. For the later monos I currently use a series connected stereo MM system (a Tonar Diabolic). Due to the tonearm with SME headshells, changing the carts is quite easy and can be performed quickly. While this modern MM cart sounds really good on all vinyl mono LPs, the GE VRII gives an absolute stunning SQ with the early mono discs way superior to the mono converted MM stereo system.
Maybe I'll check one of the AT mono MC carts to see if they are better than the currently used MM system and if they come closer to the GE carts.
The largest surprise for me was the unexpected very good sound quality for these old discs and cartridges what made me a mono lover and collector.
Thanks Aboos. That's a lot of good info.
Are your pure mono GE carts any less noisy than converted stereo carts? Does the lack of vertical compliance result in lower noise?
Are your pure mono GE carts any less noisy than converted stereo carts? Does the lack of vertical compliance result in lower noise?
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I have been tempted by the Denon 102, a mono cart for modern records and liked by the late Sakuma san who was a big mono fan. I have a mono system but no mono vinyl (stereo only), hence no dedicated mono RIAA as yet - but if I remember, there’s a tube based Mono phono for lovers of old vinyl by Diego Nardi that you can look up.
I have one speaker, can’t imagine using two for mono, but why stop there - try three, or four ...
I have one speaker, can’t imagine using two for mono, but why stop there - try three, or four ...
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Yes, they are. But only a little bit - the difference is not dramatic.
Due to the unknown wear pattern of these old records, differences can also be due to different stylus tip geometries and maybe one stylus contacts the groove wall at a point not previously be contacted and damaged while another one just contacts in areas with most wear. So you never really know.
You clearly hear a significant difference when playing a mono disc in stereo. What is irritating when playing in stereo is the fact that the music comes from the center while most noise, clicks and pops come from right or left.
Due to the unknown wear pattern of these old records, differences can also be due to different stylus tip geometries and maybe one stylus contacts the groove wall at a point not previously be contacted and damaged while another one just contacts in areas with most wear. So you never really know.
You clearly hear a significant difference when playing a mono disc in stereo. What is irritating when playing in stereo is the fact that the music comes from the center while most noise, clicks and pops come from right or left.
I considered the 102, but prices are remaining firm even for worn out ones. My friend in Russia who made my ortomono has rewound a couple of those for lower output.
You are a fast worker!
I've read this but it doesn't make any sense to me. If the lathe is fed mono then it will only cut a lateral groove. Is there any real issue here, or is it just a story?
But it works very well. The LEDs are driven by a current source and the quality of the current source together with the power supply filters on the solar cell side determines the residual noise.
There is another thread here dealing with lowest noise MC headamps (Richard Lee's Ultra low Noise MC Head Amp started by) where syn08 from Toronto developed this idea which I copied.
There is another thread here dealing with lowest noise MC headamps (Richard Lee's Ultra low Noise MC Head Amp started by) where syn08 from Toronto developed this idea which I copied.
That's a topic I have no final answer for. On the net you will find many who say that it can be played without damage while others say it will damage. Maybe both views are somewhat true. Theoretically, mono cuts are lateral only and there should be absolutely no vertical groove modulation being cut on a real mono lathe or a stereo lathe with mono drive signal.
But the two channels of the stereo cutting lathe are not noise free. Therefore there is a (very) small residual vertical component left.
The other theory is that the vinyl raw material used in the 50s and early 60s was different from the one used later. The early one was harder but more brittle - so these discs are usually thicker, havier and less flexible than the ones from the 70s and 80s. But the harder more brittle vinyl can take higher pressure without deforming and the mono cartridges from that time usually have, compared to today's standards, very high tracking forces. Maybe that's the reason why these old carts are less friendly to more modern mono records. So it would be pure coincidence that the change of vinyl composition happened at a time when these old carts were mostly not used anymore and the new records were played with modern low tracking force carts. I believe more in this second theory and the softer vinyl in combination with high tracking force of these older cartridges is the culprit and not the fact that the mono record was cut on a stereo lathe.
There is a variable unaccounted for in your comparison. In modern MM/MI (and maybe MC?) carts the signal generating element is at the opposite end of the stylus. The stylus moves the generating element by rocking the cantilever through a fulcrum i.e., the suspension. The whole system functions as a teeter-totter, with all the various unwanted cantilever shaft flexing, resonances, and what-not getting mixed in as part of the signal we are trying to retrieve. The GE VR carts are tip-sensing. The coil pole pieces straddle the cantilever at the stylus point. A large part of your favorable results with the VR's may be due to this design characteristic, and not just the fact that they are pure mono. I had much your same reaction when I first owned a Decca 4RC. The Decca carts also employ tip sensing, except in their case they are wired with a lateral coil that straddles the tip of the stylus shank, with two coils above for picking up the stereo information. I would think that rewiring a Decca cart to use only the lateral mono coil would give similar results.
Ray K