Bargains on ebay? (Part 2)

[BTH K10A]

and there is not much use for the TMD 25 cartridge.

Barry, don't you have any mono records?

I use my TMD25 all the time for older mono recordings. Wouldn't be without a true mono cartridge with the correct dia tip as the SQ is far superior.

[Barry]

Barry, don't you have any mono records?

I use my TMD25 all the time for older mono recordings. Wouldn't be without a true mono cartridge with the correct dia tip as the SQ is far superior.

Yes I do, but I'm happy to play them with a stereo cartridge and switch the preamp to 'mono'.

I disagree that the SQ is far superior by using a mono cartridge. Would agree that using a cartridge with a slightly larger radius tip of 25um is sometimes better than using one with a more modern 15um tip radius.

[spendorman]

That mid might also be Audax too, wonder if the whole system was made by Audax. Probably pretty good.

[BTH K10A]

Yes I do, but I'm happy to play them with a stereo cartridge and switch the preamp to 'mono'.

I disagree that the SQ is far superior by using a mono cartridge. Would agree that using a cartridge with a slightly larger radius tip of 25um is sometimes better than using one with a more modern 15um tip radius.

SQ is definitely better. Swapping between my TMD25 and both TSD15 & TSD15sfl using mono switch on my preamp there is a noticable difference in image clarity and much more depth and body to the sound.

This is most likely down to the impossibility of the stylus producing an identical signal into both stereo channels as it tracks the groove giving a constantly changing signal that can not true to the original recording. It might be small fluctuations but it can certainly be heard.

Also the mono cartridge has no response to vertical movement so there's no pinch effect and noise related to any wear etc is significantly reduced.

[Barry]

SQ is definitely better. Swapping between my TMD25 and both TSD15 & TSD15sfl using mono switch on my preamp there is a noticable difference in image clarity and much more depth and body to the sound.

This is most likely down to the impossibility of the stylus producing an identical signal into both stereo channels as it tracks the groove giving a constantly changing signal that can not true to the original recording. It might be small fluctuations but it can certainly be heard.

Also the mono cartridge has no response to vertical movement so there's no pinch effect and noise related to any wear etc is significantly reduced.

Switching the preamp to mono, or connecting the left and right outputs of a stereo cartridge together, means any voltage produced by vertical modulation is cancelled.

Of course there's a 'pinch effect'. The replay stylus doesn't have the same chislel-shaped profile as the original cutter head, so the stylus is not be able to trace the high frequency grooves, resulting in a sinusoidal grove being traced as triangular, thus producing a distorted output. Using a larger radius spherical tip doesn't help, but in having a larger radius it will ride higher in the grove and not read the groove wall wear that a smaller radius tip would.

[jaym481]

A stereo cartridge may have a slight channel imbalance that could cause some issues when summed, either at the cartridge by strapping the output pins, or using a mono switch. I'm not sure how important that may be, but there's an engineer fellow on Lenco Heaven who's posted a bunch of over-my-head stuff on it. His solution is a phono pre that sums the channels, but also balances them first. He posted a schematic.

I guess it's individually subjective whether it's worth the faff.

[BTH K10A]

Switching the preamp to mono, or connecting the left and right outputs of a stereo cartridge together, means any voltage produced by vertical modulation is cancelled.

Of course there's a 'pinch effect'. The replay stylus doesn't have the same chislel-shaped profile as the original cutter head, so the stylus is not be able to trace the high frequency grooves, resulting in a sinusoidal grove being traced as triangular, thus producing a distorted output. Using a larger radius spherical tip doesn't help, but in having a larger radius it will ride higher in the grove and not read the groove wall wear that a smaller radius tip would.

How does the mono switch or connecting the left and right outputs differenciate between vertical and horizontal and cancel vertical modulation only? Are you not just summing the signals which will also sum any extraneous vetical signals?

[istari_knight]

AR3a http://www.ebay.co.uk/itm/Hi-Fi-Spea...item2596a73084

[struth]

I always wonder how people can manage to get things in such a state.

[Audio Al]

I always wonder how people can manage to get things in such a state.

Looks like it may have been raining prior to getting them out of a skip