Toroidal Transformers Question??

[silverfoxnik]

Hello Folks

I have a Hughes & Kettner Bassbase 600 head that I just love the sound of, even though it's a heavy pice of kit! Part of what makes it so heavy is the toroidal transformer that powers it and though it works perfectly, it's a bit noisy when it comes to home usage..

So I'm wondering whether it could be replaced at all and if so, what would be involved?

I wouldn't do the work myself as I am not skilled at all in these matters, but before I go and ask my local electronics chappie to take on such a job, I'd like to find out a little more about it if possible..especially in terms of where to source the right part, cost implications etc, etc.

So, if anyone here's been down a similar path and has any words of wisdom to share, it would be very much appreciated!

Thanks for looking..

Cheers

Nik

[3below]

Why do you suspect the transformer? seems unlikely to be the transformer in my experience. What sort of noise, hiss or 50Hz mains hum? How good is your mains electricity - a few of my amps are noisy at home, work fine elsewhere, even though the house wiring is tested all OK. Can you borrow same amp and try at home to compare? Final shot would be take it to a good technician - as with everything in life several causes and several fixes.

Edited April 26, 2011 by 3below

[silverfoxnik]

[quote name='3below' post='1211666' date='Apr 26 2011, 02:05 PM']Why do you suspect the transformer? seems unlikely to be the transformer in my experience. What sort of noise, hiss or 50Hz mains hum? How good is your mains electricity - a few of my amps are noisy at home, work fine elsewhere, even though the house wiring is tested all OK. Can you borrow same amp and try at home to compare? Final shot would be take it to a good technician - as with everything in life several causes and several fixes.[/quote]

Thanks for the reply....

I had it checked by my local technician and he said it was definitely the transformer making the hum (as it did so when he tested it in his workshop).. He also said that with these type of transformers, it can't be cured except by replacing it with another one, which he thought might be difficult bearing in mind this particular amp is now discontinued..

At the kind of volume these amps can make, the hum isn't an isue at all when gigging, but if possible, i'd like to use the amp for practicing at home too..Hence why i thought i'd do a little research here before going back to my technician to see about replacing the transformer.

Hope that makes sense...?

[Stewart]

Transformers are generally pretty quiet (unless the windings have come loose and are vibrating)
Check that it's mounting is tight, and that any washers involved are in good shape

Toroidal simply means it's doughnut-shaped (and much less likely to induce noise (hum) into nearby wiring and circuitry than old school transformers)

If it really is noisy then a replacement should be feasible (but likely won't be any lighter... that's primarily a function of the power rating...)

[flyfisher]

All good points above.

If it were mine, I'd undo the transformer fixings (usually a single bolt through the middle with a large washer) and prop it up on a bit of foam rubber or similar, then check if this makes any difference to the hum.

If it's still noisy then it's probably within the transformer itself (loose windings etc, as mentioned above) but if it's quieter then it's probably the fixing arrangement, e.g. a bit too loose, allowing the transformer hum to resonate against the chassis. Re-fit the fixing and ensure it's really tight (thoughj not too tight to damage the windings).

[Slipperydick]

[quote name='flyfisher' post='1211795' date='Apr 26 2011, 04:38 PM']All good points above.

If it were mine, I'd undo the transformer fixings (usually a single bolt through the middle with a large washer) and prop it up on a bit of foam rubber or similar, then check if this makes any difference to the hum.

If it's still noisy then it's probably within the transformer itself (loose windings etc, as mentioned above) but if it's quieter then it's probably the fixing arrangement, e.g. a bit too loose, allowing the transformer hum to resonate against the chassis. Re-fit the fixing and ensure it's really tight (thoughj not too tight to damage the windings).[/quote]

What he said....

Try another engineer ! I assume you are talking about a noisy Tranny, ie. it buzzes, as opposed to hum coming from the speakers, which will be something else.

[silverfoxnik]

Thanks for the replies folks!

It's definitely a noisy transformer - the sound doesn't come through the speakers or the DI out. It is located above and around the transforemer itself, which is located in the rear, right hand side of the amp as you look at it head on.

As for making the adjustments and trying out the remedies mentioned above, to see if they improve matters, would you recommend them being done by someone who's knowledgeable and experienced with handling electrical equipment?

Only, this amp delivers up to a 1000 watts at 2 ohms, so it's not something I'd feel comfortable fiddling about with to be honest...

[Stewart]

Flyfisher's approach is the one I'd go for, but you're wise to be slightly wary - you've got mains going into the transformer, after all, and significant currents out the other side too.

Generally they're probably more accessible than any other component, and as pointed out are usually a single nut and bolt fitting (with a collection of washers between) - you can't really go wrong assuming you can get to it OK, but DO KEEP NOTES/DRAWINGS as you go (so you know what goes before/after what when you put it back together!)

It's quite likely that the noise is simply a loose fixing nut or any of those washers vibrating against each other/the case...

If you can remove the transformer from it's spindle fixing (lay it on a piece of wood or something) and it's still buzzing then it'll be obvious that it's the transformer at fault.

If you don't fancy it, then don't do it!

[silverfoxnik]

Ok.. Thanks Stewart!

[Mr. Foxen]

You can order new toroidals wound to spec, probably not cheap. One of the advantages of toridals is they make less mechanical noise as there is less straight length of wire to vibrate.

[silverfoxnik]

[quote name='Mr. Foxen' post='1211866' date='Apr 26 2011, 06:11 PM']You can order new toroidals wound to spec, probably not cheap. One of the advantages of toridals is they make less mechanical noise as there is less straight length of wire to vibrate.[/quote]
Thanks for that; where do you get them from??

[EBS_freak]

Try here for a start- [url="http://www.airlinktransformers.com/"]http://www.airlinktransformers.com/[/url]

[silverfoxnik]

Thanks!

[flyfisher]

Do you know the required specification though?

[Mr. Foxen]

Email H&K, they might have one, and if they don't, they might give you the spec. Peavey send me the spec for the Tmax head transformer.

[silverfoxnik]

I emailed H&K but haven't heard anything as yet, and that was 2 weeks ago.. My amp chappie is going to try and contact them too.