Good day all
What do the forum members think of useing non magnetic Brass screws and insulation for both sides of the output transformer, I read that this will improve the sound, does this mean insulating the OPTX from the main chassis and useing a solder tag to earth the transformer from static build up.
as any one tried this and if so what are the conclusions.
Acorn
Non magnetic screws
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pre65
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#2
Are they mounted on a steel, or aluminium chassis ?
The only thing necessary for the triumph of evil is for good men to do nothing.
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
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Paul Barker
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#3
you definately must isolate the screws from the lams electrically because you don't want the lams connecting together, Unless you are in the world of microwaves transformers which they actually weld together.
#4 Brass screws
How do you isolate the bolts if they are going through the lamms to keep the transformer to gether, you can isolate them both sides but the bolts will touch the lamms going through to the other side or do you have to cover the bolts with sleeving to stop that ?
Acorn
Acorn
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Paul Barker
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#6 Re: Brass screws
With nylon 6 top hats, an industry specific product. I have none left, I sent a few out to folks here when I was transformer winding.acorn wrote:How do you isolate the bolts if they are going through the lamms to keep the transformer to gether, you can isolate them both sides but the bolts will touch the lamms going through to the other side or do you have to cover the bolts with sleeving to stop that ?
Acorn
this is where I used to buy my EI stuff http://www.ascocomponents.co.uk/ look under the left menu at core insulators.
If you can find them no other place and you end up writing to Asco for goodness sake don't mention me, they wouldn't thank me for puting a customer for 8 top hats onto them. They normally deliver by weight!
Maybe someone like the contacts folk here have with transformer winders could get them from their mates for you. You have to specify your lamination size. If they are metric you measure the length of the back of the E, or for that matter the same length is the I length. So if it measures 120mm it is an EI120. Only trouble is there is also a imperial 120 just to confuse matters, but it's roughly the same.
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Paul Barker
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#7
there you go it says minimum order 1,000 any size.
That's why I was awash with them.
I got away with ordering laminations by the tray but they prefer to deliver them by the ton.
YOu will have to think of something else. how about heatshrinking the bolt and then using nylon washers where they pull down onto the face of the laminations.
That's why I was awash with them.
I got away with ordering laminations by the tray but they prefer to deliver them by the ton.
YOu will have to think of something else. how about heatshrinking the bolt and then using nylon washers where they pull down onto the face of the laminations.
#8 non magnetic screws
Update
I managed to fit four Brass bolts and insulated them with sleeving this seems to have improved the sound in lower and mid bass ,
It begs the question if this improves the leakage of the core and by doing so improve the sound , why dont the transformer makers use brass bolts and insulation to isolate the iron core and why dont they implement this as standard pracatice.
Acorn
I managed to fit four Brass bolts and insulated them with sleeving this seems to have improved the sound in lower and mid bass ,
It begs the question if this improves the leakage of the core and by doing so improve the sound , why dont the transformer makers use brass bolts and insulation to isolate the iron core and why dont they implement this as standard pracatice.
Acorn
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Paul Barker
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#9
Most use some form of isolation like the nylon 6 top hats I posted a link to, sometimes you see a fibre washer used instead, and non magnetic grade stainless.
The top hats prevent the bolt touching any of the lams if the lams are all squared together during assembly and not allowed to go higgledy piggledy.
I tell you something amaising I found when I was winding my own transformers. If you build a power transformer like a balanced transformer with a dual section bobin so that each half of the sine wave swing is exactly matched in dc resistance and inductance you get more bass in the amp. It is almost as big an effect as going to choke input. I never tried going further than that, but I recon if you assembled the core as a single ended transformer but with a butted together gap you would get an even better transformer able to cope with DC spikes. You would need to overwind it by 20% to make up for the loss of perm. Then going further than that follow Bud Purvines advise there is a trick way to stack the single ended 's and I's, the benefit of which is fast recovery from saturation reaching transients. All of this is for Shell type winding arrangements. These properties largly exist the core type winding arrangements found inside Parmeko (and the like) oil potted power transformers. these are assembled with non magnetic stainless bands and have a butt gap.
The top hats prevent the bolt touching any of the lams if the lams are all squared together during assembly and not allowed to go higgledy piggledy.
I tell you something amaising I found when I was winding my own transformers. If you build a power transformer like a balanced transformer with a dual section bobin so that each half of the sine wave swing is exactly matched in dc resistance and inductance you get more bass in the amp. It is almost as big an effect as going to choke input. I never tried going further than that, but I recon if you assembled the core as a single ended transformer but with a butted together gap you would get an even better transformer able to cope with DC spikes. You would need to overwind it by 20% to make up for the loss of perm. Then going further than that follow Bud Purvines advise there is a trick way to stack the single ended 's and I's, the benefit of which is fast recovery from saturation reaching transients. All of this is for Shell type winding arrangements. These properties largly exist the core type winding arrangements found inside Parmeko (and the like) oil potted power transformers. these are assembled with non magnetic stainless bands and have a butt gap.
#10
Well you learn something every day, I thought it was only toroidal transformers where mounting bolts could cause problems. I can't recall ever seeing a "normal" transformer with insulated bolts. I will go and have a look through my bits and pieces this instant.
Phil.
Phil.
#11
If you had/have built any the WAD/WD amps ALL the TX's were bolted down with Stainless steel bolts with those top hat isolation washers that Paul linked to. It was also recommended a cork mat be placed between the chassis and the TX lamms.Well you learn something every day, I thought it was only toroidal transformers where mounting bolts could cause problems. I can't recall ever seeing a "normal" transformer with insulated bolts. I will go and have a look through my bits and pieces this instant.
#12
Hello Toppsy,
I have a KEL84 that I built myself and it does not have any top hats under the bolts. I also have a Sowter transformer in my WD based phono stage and that doesn't have any either. There are a few other TX's in my "bits box" and none of them have them.
Phil.
I have a KEL84 that I built myself and it does not have any top hats under the bolts. I also have a Sowter transformer in my WD based phono stage and that doesn't have any either. There are a few other TX's in my "bits box" and none of them have them.
Phil.
#13
My original WAD KaT88 and 2A3PSE came with top hat washers and were referred to in the instructions. I think Colin isn't right about the kits coming with stainless non magnetic screws. They were standard steel machine screws. Also, cork or cardboard gaskets were a non original upgrade some of us went with. I finally ended up using heat resistant rubber.
I found the best way to improve things was to buy a 1m length of stainless studding, cut lengths to size and fit stainless encapsulated nuts at the cover end (top for drop through Tx's) and ordinary stainless nuts within the chassis. I have never found a ready source for top hat washers and ended up blagging an envelope full from a TX manufacturer. I'd be interested if anyone has a good supplier for top hat washers.
I found the best way to improve things was to buy a 1m length of stainless studding, cut lengths to size and fit stainless encapsulated nuts at the cover end (top for drop through Tx's) and ordinary stainless nuts within the chassis. I have never found a ready source for top hat washers and ended up blagging an envelope full from a TX manufacturer. I'd be interested if anyone has a good supplier for top hat washers.
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Paul Barker
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#14
The cork or rubber would not affect the ectrical properties because each lamination layer is isolated from the next and would also be isolated from the chassis which is painted anyway.
The reason the screws need top hats is to space them such that as long as the stack is squared together neatly centreing the screw at each end ensures it doesn't touch any of the lams and so doesn't short them by touching the unvarnished edge at the holes.
The cork or rubber must have been a vibration fix.
The non magnetic is needed because if the screw were magnetic iron it would not be the same properties as the lams and would likely be slower to give up it's magnetising force which means distortion. Whether this can be measured I don't know, it is an ideal position to use non magnetic but in reality I don't know if it counts. I haven't AB tested, I only used non magnetic as a precaution.
The reason the screws need top hats is to space them such that as long as the stack is squared together neatly centreing the screw at each end ensures it doesn't touch any of the lams and so doesn't short them by touching the unvarnished edge at the holes.
The cork or rubber must have been a vibration fix.
The non magnetic is needed because if the screw were magnetic iron it would not be the same properties as the lams and would likely be slower to give up it's magnetising force which means distortion. Whether this can be measured I don't know, it is an ideal position to use non magnetic but in reality I don't know if it counts. I haven't AB tested, I only used non magnetic as a precaution.
#15
I have dug out the instructions for my KEL84 and there is no reference to top hats in any text or drawing so this is obviously not something they were consistent about. I bought mine in mid 2006.
Regards, Phil.
Regards, Phil.