Transformers manufactured for sale in the EU are either 230Vac, or universal type being 2*115Vac.
All these transformers must be designed to run on the full range of normal voltage in the EU, i.e. 216Vac to 253Vac.
Older transformers manufactured for use in the UK may pre-date our "harmonised" supply voltage and made to operate on the previous UK voltage range of 226Vac to 254Vac.
Even these can be of the single primary, or dual primary (universal) type.
Some transformers have multiple taps on the primary. These need more careful consideration when it comes to wiring up. Get manufacturer information and wire up accordingly.
Old school are now gone, unless lying on the shelf of an old school maintenance department. Ask around.
You should have stocked up with the special offers that came in to get rid of the last few old stock.
That light in the loft that is turned on for 30minutes each year does not need you to spend extra money on very expensive bullbs.
The halogen replacements are very suitable.
They run slightly hotter to give slightly more light but with a similar life.
As such their cold to hot resistance ratio is slightly higher, but they still work as a current limiter.
Buy a range of bulbs from 20W upwards.
Small appliances need a low wattage rating to get the filament into "not quite" hot temperature.
A big bulb may not protect from all wiring faults.
Reserve the 100W for a previously tested and passed project that you are restarting.
All these transformers must be designed to run on the full range of normal voltage in the EU, i.e. 216Vac to 253Vac.
Older transformers manufactured for use in the UK may pre-date our "harmonised" supply voltage and made to operate on the previous UK voltage range of 226Vac to 254Vac.
Even these can be of the single primary, or dual primary (universal) type.
Some transformers have multiple taps on the primary. These need more careful consideration when it comes to wiring up. Get manufacturer information and wire up accordingly.
Old school are now gone, unless lying on the shelf of an old school maintenance department. Ask around.
You should have stocked up with the special offers that came in to get rid of the last few old stock.
That light in the loft that is turned on for 30minutes each year does not need you to spend extra money on very expensive bullbs.
The halogen replacements are very suitable.
They run slightly hotter to give slightly more light but with a similar life.
As such their cold to hot resistance ratio is slightly higher, but they still work as a current limiter.
Buy a range of bulbs from 20W upwards.
Small appliances need a low wattage rating to get the filament into "not quite" hot temperature.
A big bulb may not protect from all wiring faults.
Reserve the 100W for a previously tested and passed project that you are restarting.
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Right, just about ready to test it all. I have put the soft start in because that's the way it will be wires with the second pole of the switch bypassing the x cap.
However....
Both the neutral inlet and live inlet on the diy audio supplied iec mounting block has a fuse slot for each. If I don't put a fuse in the neutral side as well or short the contacts it won't power. I'm wondering why the second fuse. And is it safe to do this. If the neutral side blows first due to manufacturing tolerances then the live is still connected. What's the consensus on this?
Also when testing psu. Is it a good idea to test without the amp boards in. I take it linear supplies even when big don't mind being open circuit
However....
Both the neutral inlet and live inlet on the diy audio supplied iec mounting block has a fuse slot for each. If I don't put a fuse in the neutral side as well or short the contacts it won't power. I'm wondering why the second fuse. And is it safe to do this. If the neutral side blows first due to manufacturing tolerances then the live is still connected. What's the consensus on this?
Also when testing psu. Is it a good idea to test without the amp boards in. I take it linear supplies even when big don't mind being open circuit
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In the UK, we don't fuse the Neutral.
I don't know why the dual fused type is sold here.
I have one and it stays on the shelf.
It was used in an experiment to test the Disconnecting Network for Fault current survivability.
I don't know why the dual fused type is sold here.
I have one and it stays on the shelf.
It was used in an experiment to test the Disconnecting Network for Fault current survivability.
Should I just put a higher rated fuse in the neutral side then. The live will blow first. I guess that would be ok
Ok, well the highest I have time delay is 6amp but have higher rated fast blow I think maybe 10amp. I'm using soft start so will start lower on the live side at the schematics 1.25a but from your information I would probably need at least 2amp.
What do you reckon higher rated fast blow or 6amp time delay. If totally unsuitable I can probably pickup something higher.
Thanks for the help btw.
What do you reckon higher rated fast blow or 6amp time delay. If totally unsuitable I can probably pickup something higher.
Thanks for the help btw.
T6A in the Neutral line with T2A in the Live line might be good enough.
T2A will survive a 4A start up current based on my experience.
It may survive a much larger start up current, but I have not tried that, since it would be a destructive test.
60r of added resistance in the Primary feed with a 240Vac supply will result in a start up current <4A and the T2A will restart reliably over many months/years.
This would suit a 400VA to 600VA transformer.
T2A will survive a 4A start up current based on my experience.
It may survive a much larger start up current, but I have not tried that, since it would be a destructive test.
60r of added resistance in the Primary feed with a 240Vac supply will result in a start up current <4A and the T2A will restart reliably over many months/years.
This would suit a 400VA to 600VA transformer.
Cool, that sounds good, I think the dc resistance of the soft start was 40 something and with the thermistor added between the 2 primary windings that should be close to 60.
Btw maplin had a few old school bulbs albeit candle shape so got 28w 40w 60w and also had 150w and a 200w
Seem to be hearing some transformer hum. Nothing coming through the outputs so just mechanical. Any likely culprits? It's a sedlbauer 500va deluxe transformer (thermal cutout switches) with a cl60 thermistor between the primaries. M8 bolt into chassis although I did connect the mains ground and psu (via thermistor) ground to the same bolt as per f4 build guide. Although I noticed there was an earlier post here suggesting not to do that.
I currently have the output snubber installed which I gather I should remove.
Any suggestions?
I currently have the output snubber installed which I gather I should remove.
Any suggestions?
More rubber or neoprene washers on the transformer mounts. If the transformer hums, there's not an awful lot that can be done.
However, this is worth your attention - Mains DC and Transformers
However, this is worth your attention - Mains DC and Transformers
Ahhhh! That's an interesting point about the dc on the mains. I wonder if all my consoles etc with switch mode psu's etc are skewing things. I didn't notice the vibration on my test bench, either because it was upright or because the mains wasn't polluted locally as much. Possibly even being on a different curcuit. Either way a rubber Gromit or investigating the mains may solve it. At least I've not wired it up wrong.
How long do these psu/ amp boards take to burn in. You know to say 80/90%?
How long do these psu/ amp boards take to burn in. You know to say 80/90%?
That's interesting. Why do these take so little time? When I've done CD player mods theyve taken a while and my sonus zone player took a few weeks to break in. When I first got it the bass was very bloated and had to listen to it with the bass control on my amp rolled off quite a long way but it did settle down and now sounds pretty good. Maybe I could be accused of kidding myself with cd clocks burning in (although I don't think so) the sonus absolutely did not sound good when new and massively improved.
6l6, that wasn't meant to be questioning whether these amps indeed need little burn in, I was just surprised. But it does mean I need to figure out why the sound does have as much welly as I was expecting. Could be internal wiring and I'm maybe driving my preamp a little harder than it likes.
Some recordings are sounding really good whilst others a bit fuzzy (and veiled) around the edges compared to my mildly tweeked arcam delta 90.2.
Do you think removing he output snubber would make much difference. Sorry for the seemly daft questions, this is the first time I've dealt with large power electronics, only done line level audio and synthesizers before
Some recordings are sounding really good whilst others a bit fuzzy (and veiled) around the edges compared to my mildly tweeked arcam delta 90.2.
Do you think removing he output snubber would make much difference. Sorry for the seemly daft questions, this is the first time I've dealt with large power electronics, only done line level audio and synthesizers before
If you have a properly operating circuit, the F4 is, for all practical purposes, invisible -- it passes the sound of your source/preamp through with zero editorializing. That's the beauty of a pure follower circuit.
95% of all preamps have the volume attenuator before the gain circuit. This means that the gain circuit is running at a steady state, adding X gain all the time to the signal it sees. It's just seeing a smaller or larger signal before it does anything.
Is your internal wiring 1) copper 2) soldered properly 3) the proper length, and 4) free of open or short circuits? If so, it's most certainly not the culprit. 😀
Personally I would remove the snubber. I don't think they have a place in a Class-A amplifier.
95% of all preamps have the volume attenuator before the gain circuit. This means that the gain circuit is running at a steady state, adding X gain all the time to the signal it sees. It's just seeing a smaller or larger signal before it does anything.
Is your internal wiring 1) copper 2) soldered properly 3) the proper length, and 4) free of open or short circuits? If so, it's most certainly not the culprit. 😀
Personally I would remove the snubber. I don't think they have a place in a Class-A amplifier.
I'm pretty sure that's how my preamp is. But by turning an already hot ish line signal I'm wondering if the output stage is saturating a little, I've never run it this high before (rough and ready reckoning with scope with volume at 2 or 3 o'clock its putting out about 12v pp on kick drum so I reckon it's getting close.
I think the cabling maybe an issue.
I'm using some sommer source mic cable (short run about 7 inches) with one conductor soldered to screen at both ends. It's copper but would probably want some silver at some point. Have been using some silver ic for CD player for about 10 years and have always been happy with the sound. I also use the sommer to connect my pmc monitors via this preamp and that's been ok.
I definitely need to do something about the speaker output. I had bought a length of chord odyssey2 but turned out to be a bit thick so got some 6amp mains cable for the time being. But only using about6 inches internally. Although not sure about the crimped spade connectors getting to the speaker connectors
I also think I could bias the boards a little hotter.
Maybe getting off topic here, I'm also posting here
http://www.diyaudio.com/forums/pass-labs/234355-guide-building-pass-f4-amplifier-69.html
So you could reply here if I'm wrecking things!
Thanks for the help!
I think the cabling maybe an issue.
I'm using some sommer source mic cable (short run about 7 inches) with one conductor soldered to screen at both ends. It's copper but would probably want some silver at some point. Have been using some silver ic for CD player for about 10 years and have always been happy with the sound. I also use the sommer to connect my pmc monitors via this preamp and that's been ok.
I definitely need to do something about the speaker output. I had bought a length of chord odyssey2 but turned out to be a bit thick so got some 6amp mains cable for the time being. But only using about6 inches internally. Although not sure about the crimped spade connectors getting to the speaker connectors
I also think I could bias the boards a little hotter.
Maybe getting off topic here, I'm also posting here
http://www.diyaudio.com/forums/pass-labs/234355-guide-building-pass-f4-amplifier-69.html
So you could reply here if I'm wrecking things!
Thanks for the help!
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Are your interconnects and speaker cabling 1) made from clean, tarnish free metal of good conduction 2) soldered properly 3) the proper length 4) with the proper connectors at both ends, and 5) free of open or short circuits? If so, it's most certainly not the culprit.
😀
😀