Rb301 Ground Wire Mod

[tiller]

Hi all,

First post!

I notice there are quite few posts on this topic, but none which address the specific question I have.

First of all, I wanted to add a dedicated ground wire to my RB301 today in hopes of lowering the noisefloor. After getting tone arm off and the base plug pulled out, I could not figure out how to separate the solder terminals from the rubber plug so that I might add an additional wire.

Has anyone added a ground wire to their RB301 before? How did you separate the solder terminals and the base plug? Was this mod worth it at all?

Cheers,
Adam

[wobbleu]

In my view it's a bit of a pointless exercise - although I have no direct experience of hearing a re-wired RB301.

The earth for the arm is carried in the right channel - there's a copper tag in the back of the arm (behind where the cw stub screws in) with a black wire. I'm assuming this is joined with the r/h earth wire in the base plug.

The wire used for the external cable is pretty good stuff (I use the same Klotz cable for my home made interconnects)

If you are set on doing it then a full rewire is probably the best option - there are a few kits available or you can source your own - I've seen a few postings around the web where using the wrong wire has caused problems with the free movement of the arm - so you need to take a bit of care.

If I was convinced that a re-wire would make that much difference I think I'd leave it to one of the 'experts' to do it for me eg: Audio Origami.
I'd rather have a record deck that works at 95% efficiency than one I'd junked by my own clumsy mitts!

[Mike-h]

Not wishing hi-jack the OPs post, but what type of cable is used for the earth? All rewire kits just supply the 4 cartridge leads.

[JaS]

This might help?

Hot Wired Rega

Regards,
JaS

[zharca]

There's a very quick and dirty fix you can try to see if separating the ground wire out makes any difference.

Undo the little grub screw that holds the base plug in place (1.5mm allan key),

Ease the base plug out a little - careful, don't pull the wires inside. You can get maybe 5mm of clearance.

Unsolder the ground lead from the little brass tag. and strip it back a bit (really burn off some of the insulation with a soldering iron).

Put the ground wire on the outside of the base plug so that it contacts the metal base when the plug is put back.

Put the plug back in the same position, don't twist it round as it has been set so the wires don't pull as the arm rotates.

Wrap a ground wire round it and secure it with the locking nut.


If this makes a difference it's worth doing a more permanent, soldered ground.

All rewire kits just supply the 4 cartridge leads.

mine don't

[tiller]

wobbleu: I see what you are saying, and I have to say that I don't buy into the whole cable thing myself. As a recording engineer I use plenty of regular ole cable for low-level, critical signals, and never find myself wishing for boutique stuff. My reasoning for doing this mod is that I don't like the idea of the chassis ground being tied to the signal ground. The should be separate to the pre-amp. However, I am also not convinced that this will make an enourmous difference in this application, hence my enquiry.

Yeah zharca, I had entertained the idea of ghetto-rigging a wire around/outside the base plug (as opposed to through the base plug with the audio leads) as a temporary thing, but I don't want to half-ass a solution. If I could separate the solder terminal plate from the base plug it wouldn't be a problem.

JaS: thanks for the link. It was this document that I consulted before attempting the mod. Unfortunately they are doing a complete rewire so they snip off the audio leads and all the tonearm wire and basically muscle the thing apart. Since I'm not doing a complete rewire, their method isn't entirely relevant.

I have pretty much retired the idea of doing this mod simply because the complete lack of user reports on the mod tells me it's not going to be anything really beneficial. That said, I'd love to hear from anyone who has added a dedicated tone-arm ground without doing a complete rewire and whether or not it made a difference.

Thanks for the responses all!

[philmch]

I'm not making any great claims for this but in my own case I've got an RB250.

I've glued on a piece of old bell wire to the locknut using super glue and clamped the other end to the ground terminal on my Pro-ject pre amp.

Worth a try perhaps and won't do any harm.

[tiller]

did you notice any difference at all, philmch?

[philmch]

did you notice any difference at all, philmch?

Very little to be quite honest. I could swear it's quieter with the arm locked in place and the volume turned up but I'm quite prepared to accept that I'm wrong. I'm using an AT95e through a Phono Box and as far as I know, the original Rega grounding is still in place.

[tiller]

Okay, thanks for the insight!

I still haven't had my original question answered, unfortunately. Does anyone know how to separate the solder terminals from the base plug so that I might run the new ground through the base plug with the audio leads?

Thanks!

[zharca]

The plug is a moulding with the terminals and the interconnect. There's not really a way to separate parts of it. It would be possible to drill perhaps a 2mm hole through it for a ground wire.

Just remember one thing: there's a very good chance that at your pre-amp the ground connection and the phono socket -ve are all connected together. I think there's very little point in separating out the ground unless you are using a pseudo-balanced cable with two signal wires and a separate, grounded screen.

[tiller]

Thanks for all the information folks.

The amount of hum I am picking up off my deck has been driving me insane. In an attempt to isolate the problem I went ahead and did the ground wire mod. I broke the connection between the tonearm ground and the left channel signal ground, and added a dedicated run from the tonearm ground to my preamp.

(If anyone is curious, this really didn't make much of a difference at all. It appears my cartridge - an Exact 2 - is picking up a shitload of EMI from something in my apartment. Before you suggest it, I have tried tracking it down and its none of my other gear or furniture or appliances or lights... etc)

Now, I would like to take this a step further and also properly ground the motor. Has anyone done this? I believe the motor casing is plastic, no? Where would be a good place to ground the motor before going to my preamp?

Cheers!

[desana]

Hi

Before you go ahead and dismantle your table could you maybe upload a mp3 sample off the hum you get.
Might help in figuring out what is causing the problem

In my experience a working Rega Exact 2 should not pick up any noticable hum from the tt, so I'm abit conserned that adding alot off extra ground wires around is only going to cause more grief for you and not solve anything.

Also check that no walwart transformers are close to the tt / riaa box, if you have a TV connected to the amp try disconecting it same with radio reciver if your on cable TV

[tiller]

Thanks for your thoughts desana.

I was trying to avoid typing out the entire process I've gone through in order to isolate the problem to the cartridge. I am pretty confident when it comes to this sort of troubleshooting and understand what to watch for, etc.

I really just wanted some advice as to where to look to find a good spot to ground the motor.

Nevertheless, let me try and sum up my process as briefly as possible:

1. I have tried all different combinations of interconnects and equipment. I went so far as to pairing down my setup to Rega -> Preamp -> Headphone amp. The preamp is dead quiet when the inputs are shorted, as is the headphone amp. The preamp -> headphone amp is dead quiet with the preamp's inputs shorted. The hum is introduced as soon as I plug the Rega into the preamp.

2. I have tried all manner of temporary grounding schemes, none of which improve the situation. Obviously, grounding certain things makes the problem worse as it introduces potential ground loops. This has been accounted for. I have also tried all the gear on different power outlets on different circuits in my apartment.

3. The Rega picks up the noise regardless of whether or not it is plugged in (to the mains) and whether or not it is turned on.

4. The cartridge picks up significant amount of hum (which is a different hum from the main one, but further backs up my claim of a poorly shielded cartridge) from the motor. This only happens when the deck is powered on. As you would imagine, this hum increases towards the spindle.

5. The (main) hum is reduced about 85% when I swap the cartridge for an old Shure POS I have kicking around.

[At this point I believe it is fair to say that the cartridge is the offending PICKUP of noise]

6. Moving the tonearm/deck changes the sound of the (main) hum. Moving it around the room changes it as well. I have moved every single piece of my other gear (refrigerator included) whilst keeping the deck stationary, and there is no resultant change. The only thing that changes the noise is moving the tonearm/deck. This tells me its none of other my gear, and probably something with the wiring in this building or something.

So there you have it. If you feel I've missed something, I'm all ears. I will probably just figure out where to ground the motor myself. I don't expect it to fix the main problem I am having here, but I figured it couldn't hurt.

Cheers,
Adam