Rega RB300 - Balance problems + microphonic cable

[The Chronicals]

So, I invested in a newer RB300 for the gyrodec. The existing one had seen better days cosmetically and I got it fairly cheap, so thought it would be a nice clean up, but have some issues.

Issue 1

Putting the dial at 3.5 (so the internal bias spring is disengaged) it wont allow the arm to balance with the Nagaoka - the technoweight is off the end before it even begins to lift it up at the shell end. If I move the dial to 3 it will balance - just, but I am told this is not the best way to balance it with the technoweight, and the internal bias spring should be fully disengaged and the technoweight takes over the duties soley.

The previous arm balanced fine with the internal spring turned off at 3.5.


Issue 2

The new one, wired with the same Incognito tonearm wiring as the old one - has a very microphonic cable. Just moving the arm can be heard through the speakers, and forget about moving the cable itself - its like its fully amplified in doing so. Scratch the cable and its literally like a microphone.

and same arm, same wiring, same cartridge - this new one is SUPER bright, some might like it, but I prefer the more laid back warm sound I had previously.

Ive done what I can - moved the arm cable around, checked VTA, tried different tracking forces nothing changes it.

Im fairly new to this, so I'm wondering have I missed something?

The only thing I havent done yet is put the old arm back on.

Any helps!? Cheers in advance!


The one noticeable difference - take the screw thread cap thingy off the end of the arm has a piece of metal at the end - the new one has a red cable soldered to it, the old one is just floating around with no cable attached (although looks like it has had previously)

[Barry]

Not sure if this will help with your microphony problem, but at one time I had problems with 'handling noises' when using a Decca Mk. VI on a damped SME arm. It turned out that there was inadequate connection of the signal returns from the cartridge. Once this was sorted out the system was quiet with no handling noises at all.

[The Chronicals]

Not sure if this will help with your microphony problem, but at one time I had problems with 'handling noises' when using a Decca Mk. VI on a damped SME arm. It turned out that there was inadequate connection of the signal returns from the cartridge. Once this was sorted out the system was quiet with no handling noises at all.

Hey Barry, thanks for the reply.

Are you taking about the cartridge tags? I did compress them a fair bit earlier to make a solid tight connection on the cart pins - or am I taking about something entirely different?

[Barry]

The Decca cartridge has the generator coils wired in a 'sum and difference' configuration, so only has three cartridge pins, the 'ground' being common. This then introduces the dilemma of what to do with the extra signal ground lead in the headshell. In my case I found I had to connect both to the single ground pin of the cartridge.

Clearly this is distinct from your problem, so I would suggest you check to see if the metalwork of your arm is correctly and separately grounded at the preamp.

[hifi_dave]

I can't help with the Tecnoweight business but would suggest the internal wiring appears to need attention.

As a Rega stockist, I have lost count of the number of their arms I have had to get repaired following an Incognito or other rewire. On the face of it, an internal rewire is easy but it's not. To do the job properly, the arm needs to be dismantled to allow free movement of the wire through the bearing housing. That is rarely done and the result is sticky bearings and electrical problems such as you have. Even Michell take their Tecnoarms to Rega to be wired and set up.

[The Chronicals]

The Decca cartridge has the generator coils wired in a 'sum and difference' configuration, so only has three cartridge pins, the 'ground' being common. This then introduces the dilemma of what to do with the extra signal ground lead in the headshell. In my case I found I had to connect both to the single ground pin of the cartridge.

Clearly this is distinct from your problem, so I would suggest you check to see if the metalwork of your arm is correctly and separately grounded at the preamp.

Cheers, the preamp has its own earth which the tone arm cable connectors to.

The only anomilty I can see is this thread at the back of the tone arm with a red cable wired to it. On the old one, that thread is there, but no cable wired to it.

I can't help with the Tecnoweight business but would suggest the internal wiring appears to need attention.

As a Rega stockist, I have lost count of the number of their arms I have had to get repaired following an Incognito or other rewire. On the face of it, an internal rewire is easy but it's not. To do the job properly, the arm needs to be dismantled to allow free movement of the wire through the bearing housing. That is rarely done and the result is sticky bearings and electrical problems such as you have. Even Michell take their Tecnoarms to Rega to be wired and set up.

It could quite be. I am told it was 'professionally' done, but there are good professionals and bad ones as we all know

It seems this is common with the Icognito kits from looking around on the web.

Where does the rega arm internally earth to?

I will try and take some photos later of the 'bit at the back'

[hifi_dave]

I have seen Rega arms damaged by 'professionals'. No name, no pack drill. It's not an easy thing to do. Occasionally, it can be done without issue but it's not something I would tackle.

The un-modified Rega arm is earthed via the right hand screen.

[The Chronicals]

I have seen Rega arms damaged by 'professionals'. No name, no pack drill. It's not an easy thing to do. Occasionally, it can be done without issue but it's not something I would tackle.

The un-modified Rega arm is earthed via the right hand screen.

Thanks - it seems the earlier Incognito kits had the earth inside the din type connector - as you said, through one of the screen channels, but the new one has a seperate earth, which is to the earth bond at the back of the arm (thats what that small piece of metal is in near the bearings for it seems)

Still a 'scratchy' cable - but John at Origami thinks this is just a charateristic of all in wiring jobs - apparently it wont really be an issue at all - just an OCD type annoyance

Regardinf the balance issues - even though the VTA looked correct on a spirit level, the arm still would'nt balance correctly.Ive moved it up about a mm, and now it balances fine! Witchcraft.

The brightness turns out the switch from a 30mm Granite plinth with Vibrapods to a 15MM acrylic plinth of sorb balls - the Granite provides a much more more bassy and smooth sound, but the acrylic was far more detailed - I am very suprised these affected the sound that much, but it was a great deal - even noticeable by my tone death flatmate