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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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12th Apr 2021, 6:32 pm | #21 | |
Tetrode
Join Date: Mar 2021
Location: Lancashire, UK.
Posts: 57
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Re: Sylvania Console amp
Quote:
It is good to see this emblem on another piece of equipment, thanks for posting that. |
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12th Apr 2021, 6:35 pm | #22 | |
Tetrode
Join Date: Mar 2021
Location: Lancashire, UK.
Posts: 57
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Re: Sylvania Console amp
Quote:
Also I now have the equipment to bring up other old amps slowly if needed. Cheers! Kyri |
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12th Apr 2021, 6:45 pm | #23 |
Dekatron
Join Date: Nov 2009
Location: Lincolnshire, UK.
Posts: 4,985
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Re: Sylvania Console amp
I think you've got it sorted...and yes, you'll have to be careful not to disturb the adjustment on that Variac once you've got it set to the required voltage - it's very easy to find it's been moved when your back's turned! The standard type quick blow fuse may be OK, but if you still get random blowing on switch on, then you'll need the anti-surge version of the same fuse, there's unlikely to be any problems with the smoothing capacitors. Remember, from cold the rectifier won't be letting any DC voltage into the capacitors until it warms up, and then it'll be relatively gradual, the only time there will be an 'inrush' is if you switch the amplifier off and then on again quickly afterwards without letting the rectifier cool down. Your fuse blowing is due to you catching the peak half cycle of the mains waveform hitting the transformer as you close the switch - it doesn't catch it every time and you get away with it a few times and then the fuse blows, so try an anti-surge 1 amp and see how it goes.
There's one permanent answer to this voltage thing, and that is to get the original transformer rewound for UK mains - there's a couple of professional transformer rewinders on this forum that could advise and do the job for you, but whether it would be worth it for that amp is another question. I don't think you've confirmed the valve line-up yet - unless I've missed it. |
12th Apr 2021, 7:21 pm | #24 |
Tetrode
Join Date: Mar 2021
Location: Lancashire, UK.
Posts: 57
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Re: Sylvania Console amp
Thanks that is good information. I will get some of these fuses you mention.
Regarding the valves they are 5Y3GT rectifier, 12AX7 preamps and 6BQ6 power valves. I really like this amp. There is an elegance and simplicity to it, and I wonder how many different songs have been played through it since the early 60's. |
12th Apr 2021, 7:49 pm | #25 |
Dekatron
Join Date: Nov 2009
Location: Lincolnshire, UK.
Posts: 4,985
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Re: Sylvania Console amp
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12th Apr 2021, 8:03 pm | #26 | |
Tetrode
Join Date: Mar 2021
Location: Lancashire, UK.
Posts: 57
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Re: Sylvania Console amp
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12th Apr 2021, 8:14 pm | #27 | |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,302
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Re: Sylvania Console amp
Quote:
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Edward. |
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14th Apr 2021, 8:04 pm | #28 | ||
Tetrode
Join Date: Mar 2021
Location: Lancashire, UK.
Posts: 57
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Re: Sylvania Console amp
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Well, this does sound interesting, and I might consider it in the future. Thanks for that idea. In the meantime, I have some upgrades I want to do to the variable transformer, the first is measurement using a cheap meter which I checked and seems close enough to avoid me having to check it every time with a proper meter. Then I may fit the meter / wiring inside the box and make a brake of some sort (like a mini disc brake on a bike) that I can tighten to clamp on the dial to stop it moving once it is set. |
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16th Apr 2021, 4:57 pm | #29 | |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,526
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Re: Sylvania Console amp
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Worst case inrush occurs when switched on at zero crossing with the rising voltage producing a field in the core in the same direction as any residual field. This causes core saturation part way up the first half cycle and a consequent massive inrush current spike as the primary inductance falls from Henries to millihenries when saturation occurs.
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17th Apr 2021, 6:36 pm | #30 |
Tetrode
Join Date: Mar 2021
Location: Lancashire, UK.
Posts: 57
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Re: Sylvania Console amp
Hi, and an update:
I got some slow blow fuses in 1A and 2A. The volt/ammeter was attached to the transformer (I have not yet cut a rectangle to fit it in neatly) and fired up the amp. The current at 117V is around 0.5-0.6A so I changed the 2A fuse for a 1A and so far so good. I wouldn't be concerned if it needed the 2A fuse, will see how it goes. For over an hour I have used the amp to listen to various things, inspired by the vintage speaker thread - I looked for things with a wide range of frequencies and good stereo. I am convinced that this setup will allow me to get more enjoyment out of existing music, but also appreciate new things as I have a good reason to listen to new music or types of music. I have a varied taste so look forward to listening out for different sounds and instruments in the music. Anyway - after over an hour, the amp appears to run cooler, transformer barely warm, mains cap cold and only just warmed a little I think from conducted heat from the chassis. I am debating whether to change those caps still, but for the moment am using it as-is. Cheers Kyri |
25th Apr 2021, 10:46 am | #31 |
Tetrode
Join Date: Mar 2021
Location: Lancashire, UK.
Posts: 57
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Re: Sylvania Console amp
Regarding the smoothing can capacitor, it has values of 80/40/20 MFD
If I replace the cap with some new ones, I could use ones I have seen with values at 82mfd and 22mfd. If I use two 22’s in parallel for the 40 value, a single 22 for the 20 value, and 3 in parallel for the 80 value, is this OK. I could go higher in capacitance as I read this is ok – but is there any disadvantage? The new ones are the same voltage rating as the old. Alternatively I can use the 82 single cap for the 80 value. If I do it, I will not take the old can out, just find a way to get the connections in the correct way for the new caps. I am still undecided about doing it but welcome views on the values vs. Originals. One thing I did learn, is not to replace the existing one with an exact original as it may be dried out even if not used, hence the search for new ones which unfortunately don’t have the same exact values. |
25th Apr 2021, 11:44 am | #32 |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,302
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Re: Sylvania Console amp
80uf is a really high value for smoothing. Use nearest values. I would have though that 50+50+22 would have been fine at 350V.
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Edward. |
25th Apr 2021, 3:38 pm | #33 |
Octode
Join Date: Dec 2018
Location: Llandeilo, West Wales, UK.
Posts: 1,092
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Re: Sylvania Console amp
As you tell us the current can stays cool and you are not complaining of undue hum from the speakers, why change it / them?
The 5Y3 has a maximum filter cap rating of 20uF (22uF is fine), so suspect the 40 and 80uF caps keep the HT hum level down as the amplifier is single ended. If you do replace them, 22uF, 47uF and 68 or 82uF values would be fine. Just follow the voltage rating printed on the original can or measure the maximum HT volts and add 50 to that. Also best to choose a 22uF cap with a good ripple rating for filter duty. Alan
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26th Apr 2021, 6:38 pm | #34 | ||
Tetrode
Join Date: Mar 2021
Location: Lancashire, UK.
Posts: 57
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Re: Sylvania Console amp
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I note what has been said about the values and the ripple rating - thanks! It is interesting that as I use this amp and compare it to others, it has a bass rich (but clear) tone with good treble, but not scooped, if that makes sense. I am really enjoying it. |
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