ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
I've been using my father's Beogram Rx pretty consistently since I absconded with it over 20 years ago. I last replaced the cartridge with a Soundsmith SMMC4 in 2011. Everything sounded fine the last time I used it, before going out of town, but when I played a record last night, the bass was extremely distorted. I tried different records, including a brand new one that sounded fantastic last time I played it. Is it possible that my stylus suddenly gave up the ghost, or is there something else I should be concerned about?
2 suggestions: the needle tip had fallen off. This can be observed under a microscope, or the suspension of the cantilever got loose. You may try to give the tonearm a little push down to the record while playing. And yes, the bad suspension is not only an issue of the original pickups from B&O, it happened to my SMMC4 from Soundsmith as well. It was only e few months over warranty and Mr. Ledermann sent me a new one.
After checking the stylus tip as ProGram suggested for both cord and the diamond, I would not push down on the tonearm but instead check to see if the tracking force is correct by rebalancing the arm. If the suspension has given out then this will be visible at the correct tracking force.
PLOT TWIST.....
I decided to give it another try when I got home from work, and.... It sounded fine. Just to make sure, I put on a near mint copy of a very cleanly produced record (Gene Clark's Early L.A. Sessions), and turned the bass up. It sounded as clear as ever. Then, halfway through a song, the bass frequencies in the left speaker suddenly became distorted. I run two sets of speakers concurrently- one in the kitchen and one in the living room. I was in the kitchen when the distortion started, so I dashed into the living room and verified that the same was happening there. I quickly switched to FM to see if that was affected, and lo and behold, the left channel was distorted on FM. But then, suddenly, it went back to normal. I proceeded to listen to records and the radio all day yesterday without any distortion.
So it's clear that the issue is not actually with the Beogram, but the amp (a Cambridge AXR85). Whatever it is, it's transitory, and that's why it seemed like it was happening on records but not radio before- it must have stopped by the time I tried other inputs on the night I noticed the problem.
I'm hoping the problem will stay away for good, but I'm worried it will re-occur right after the warranty on the amp expires.
Thanks for you replies and suggestions, but it looks like I need to post in a Cambridge Audio forum. After 30+ years, my Beogram RX continues to work flawlessly. If only everything I owned was this reliable!
I am thinking that I may buy a backup stylus all the same, simply because one never knows how long Sound Smith will continue making them, and because their prices have risen significantly since my last purchase, and will no doubt continue to do so.
Glad to hear the problem is in a component under warranty. This type of intermittent issue will not fix itself so you should get it repaired. Before doing so it will help the tech if you can pin down the circumstances leading to it failing. For example, if it does it after nn minutes with one set playing but xx minutes with two sets.
I've been playing music all weekend, trying to recreate it, but so far it hasn't re-occurred. I'm afraid that if I send it in for repair they won't be able to recreate it either, and so won't do anything, and I'll have gone through the hassle (and suffered without a stereo) for nothing. I bought the unit as a refurb with warranty direct from Cambridge Audio almost a year ago, and I ponied up for an extra 1 year warranty through Square Trade, so technically I'm covered for another year+.
Mark: If the suspension has given out then this will be visible at the correct tracking force.
Hi Mark,
Could you please elaborate on this?
What I would is understand how to asses a cartridge state.From what I read from the beogram 4002 design story booklet is that suspension is related to compliance and related to bass rendering.I've also read that the cantilever should be parallel to the axis of the cartridge (sideview).
I believe and have experienced that if the head does not track, its often because te tip/diamond is too much worn.
Also that high/medium distortion is also related to tip wear.
Those, seems to be actual facts.
So understanding what you said would be an insight more.
Thank you in advance.
M.
Generally on a moving iron or magnet cartridge the diamond wears out far quicker than the suspension which usually consists of a piece or elastomer. If the cartridge has been unplayed for years but still has a good diamond the elastomer can become brittle which results in it no longer supporting the cartridge at the designed vertical tracking angle and sagging where the guard can hit the record. Many normal cartridges are designed so that when their body is parallel to the record the VTA is correct. That is not the case with the 400x series since the arm is parallel when it is in the up position. Therefore B&O designed the cantilever angle to take this into consideration.
Thank you Mark,
So if I understand well, with a bad suspension at the right pressure, the cartridge will "crash" on the record, right?
What I don't understand and it may be related to language is, "brittle" means "hard and breaking". Then I understand an hard suspension would reduce bass rendering by cutting movements of the tip, but woulnt it, on the contrary keep the cantilever right and the cartridge up? I would think the contrary: a too much soft suspension will crash the head, like too old dampers on a car?
I know you are right, and I'm not discussing, I just want to understand.
In my case, I have many old B&O cartridges SP's and MMC's. I can hear some more than other have a tired diamond, little to mid distortion in the highs, typically choirs or loud voices. I expect those cartridges to also have tired suspensions, but 1-they stand high over the record as expected and 2-Low medium to bass rendering is (seems to me) good to very good.
How is all this related?
Tanks.
Aging is obviously a continuous process and I only have my tech experience to draw from versus working for a cartridge manufacturer. If you think about it as the suspension becomes less elastic, it will resist the stylus movement which is more pronounced on bass frequencies where stylus wear will prevent the cantilever from tracing treble frequencies. Once the suspension loses all elasticity the record grove vibrations can cause it to crack and give way resulting in the cantilever no longer supporting the cartridge. This elastomer is very much a proprietary formulation for many manufacturers and so lifespan varies due to that as well as environmental conditions. While stylus life is measured in hours, there are no standards for suspensions beyond testing their compliance and distortion.