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SAM2811

Help Needed to Choose the correct Step down Transformer for the TUBE AMP

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Just wondering is there a step down transformer needed for this Integrated Tube amplifier specification.

 

I have done quite a extensive research on it but none of them explained clearly about the correct step down transformer

 

It says 110v @8amp / 220v @4 amp and there is no switch at the back of the amplifier to make sure it is either running at 110v or 220v. I think it will automatically switch according to the figures.

 

Some people are telling that the tubes will not last long if we don't use a step down transformer. Others telling that it should be fine @ 240v ( VICTORIA) and it doesn't require a step down transformer. Could anyone just help me. I just want to protect my equipment.

 

 

 

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Guest Muon N'

If it is 220vac and run on 240vac or higher that percentage over voltage will be reflected in the secondary feeds, so heater voltages will be higher than they should be, B+ will be higher than it should be, but the higher heater voltage will be what shortens the tube life.

 

Do you know what the voltage at the wall is in your home? it can vary from suburb to suburb.

 

Anyway, go for a quality step down with plenty of headroom in regards to VA rating, Tortech in Sydney make good ones and can custom make them also on request.

 

Might help if you specify what brand and model the amp is.

 

Also make sure it is set to the voltage you require, likely best to talk with the manufacturer of the amp you have to confirm requirements.

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48 minutes ago, Muon N' said:

If it is 220vac and run on 240vac or higher that percentage over voltage will be reflected in the secondary feeds, so heater voltages will be higher than they should be, B+ will be higher than it should be, but the higher heater voltage will be what shortens the tube life.

 

Do you know what the voltage at the wall is in your home? it can vary from suburb to suburb.

 

Anyway, go for a quality step down with plenty of headroom in regards to VA rating, Tortech in Sydney make good ones and can custom make them also on request.

 

Might help if you specify what brand and model the amp is.

 

Also make sure it is set to the voltage you require, likely best to talk with the manufacturer of the amp you have to confirm requirements.

Thanks for your reply. My Voltage fluctuates between 230v - 245v but most of the time stays between 238v - 242v. 

 

Just wondering with that specs at the back of the amp can I use 110v stepdown transformer or 220v step down transformer. Both I am trying to use tortech only.

 

This is the Spark 530 Integrated Tube amplifier. There are no info about it online as well. 

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Guest Muon N'

Sorry, without the owners manual or the service manual I couldn't say definitely, it may have to be switched inside or wired for one or the other, or it might be self sensing, I really couldn't say.

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Guest Muon N'

Hang on!

 

@Al.M has one of these amps, Spark now Cayin brand apparently, maybe he can help.

 

 

Edit: nice amp.

 

Edited by Muon N'

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8 hours ago, SAM2811 said:

It says 110v @8amp / 220v @4 amp and there is no switch at the back of the amplifier to make sure it is either running at 110v or 220v. I think it will automatically switch according to the figures.

Very very unlikely there will be an automatic detection/switch. More likely there will be an internal switch/selector so you will need to open the unit, locate and set the selector, normally very easy.

 

Power generation has a max tolerance of 6% so your 240V could be 254V, so running on the 220V setting would be problematic.

 

Two types of stepdown, autotransformer and isolated. The autotransformer has a single winding with a tap, they are cheaper but a windings fault may mean mains voltage on your item, maybe not a big issue since 240->220V, more of an issue for 240V->100V etc... The isolated transformer has 2 separate windings.

 

I would go with the isolated type, at full power the amp draws 880VA, you could probably get by with 1000VA but I'd spend the extra $20- and get a 1200-1500VA unit. Wouldn't go higher as that creates "problems" with supply voltage.

 

Some people opt for a "buck/boost" transformer which just tweaks the extra 20Vac, don't know much about them, think they are autotransformers and fairly cheap, worth doing some research...

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The transformer will have 2 primary windings, the voltage selector will either connect these windings in series (220V operation) or in parallel (110V)

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Guest Muon N'

I agree with, Mike....that it would not be auto, and either a switch is there somewhere or it has to be rewired if changing from 110v - 220v.

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11 hours ago, Muon N' said:

Sorry, without the owners manual or the service manual I couldn't say definitely, it may have to be switched inside or wired for one or the other, or it might be self sensing, I really couldn't say.

Could you let me know what is required on the owners manual?? I can send you the pics of it thanks

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Guest Muon N'
8 minutes ago, SAM2811 said:

Could you let me know what is required on the owners manual?? I can send you the pics of it thanks

No idea, I don't have it and couldn't find it on the net.

 

If you take a hi res pic underneath with the bottom plate off and upload it here maybe we can see if there is a switch, or if it is hard wired for 220vac.

 

Was it purchased here? did the previous owner indicate anything around use?

Edited by Muon N'

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4 hours ago, mbz said:

Very very unlikely there will be an automatic detection/switch. More likely there will be an internal switch/selector so you will need to open the unit, locate and set the selector, normally very easy.

 

Power generation has a max tolerance of 6% so your 240V could be 254V, so running on the 220V setting would be problematic.

 

Two types of stepdown, autotransformer and isolated. The autotransformer has a single winding with a tap, they are cheaper but a windings fault may mean mains voltage on your item, maybe not a big issue since 240->220V, more of an issue for 240V->100V etc... The isolated transformer has 2 separate windings.

 

I would go with the isolated type, at full power the amp draws 880VA, you could probably get by with 1000VA but I'd spend the extra $20- and get a 1200-1500VA unit. Wouldn't go higher as that creates "problems" with supply voltage.

 

Some people opt for a "buck/boost" transformer which just tweaks the extra 20Vac, don't know much about them, think they are autotransformers and fairly cheap, worth doing some research...

I agree with you about choosing the step down transformer. But I can confirm that the previous owner was using it directly plugged in to the wall socket (240V Supply)

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11 minutes ago, Muon N' said:

No idea, I don't have it and couldn't find it on the net.

 

If you take a hi res pic underneath with the bottom plate off and upload it here maybe we can see if there is a switch, or if it is hard wired for 220vac.

 

Was it purchased here? did the previous owner indicate anything around use?

It wasn't purchased here but I just had a word with the owner and they said it was directly plugged in to the 240v wall socket and they used it rarely for almost 4 years it seems 

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Guest Muon N'

@SAM2811 OK, so It's setup for 220vac, so you need a 240vac stepping down to 220vac.

 

For VA rating if for instance the amp has a ratted power consumption of say 250 watts, I'd get a step down rated for 500 watts.

What does it say on the back for power consumption?

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SAM2811 and I have previously been exchanged mails. Another poster Whim43 has provided the circuit diagram and I have attached the manual pics below. 

 

If your house voltage is higher it is best used with a 220v stepdown just to be safe and for the long term. It can be used without but personally I don’t leave it on for longer than needed such as an hour to warm up before listening and off afterwards. I wouldn’t leave mine on all day or longer than needed as tube life would reduce unnecessarily at both voltages (220 or 240+250v) and it risks the issues already mentioned above by others.

 

 

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Edited by Al.M

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It should not be used on 240VAC.

The filament voltage of all the tubes will be over their allowed maximum and tube live will be shortened substantially.

This being a chines build amp all the components are not likely overrated so they will be running at their limits.

Not to mention that your operating voltages are not at their ideal.

A 500W step down TX would work nicely.

But it is still a chines amp!

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Guest Muon N'

It's really a Cayin amp, they are/were built pretty well.

 

Edit: still no reason to run on 240vac without using a step down though, I agree :)

Edited by Muon N'

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Sorry for the delay, I have contacted the original owner and he got back to me this morning

 

Dear Sam,

 

This is going back a few years.

 

You need not worry about the line voltage. Inside the KT88 amp, I have added a small autotransformer to correct the B+ (high voltage for the anodes of tubes). This was manufactured by Southern Electronic Services (SES) in Dandenong.

 

I have also checked the voltages and currents applied to the tubes and made sure that these are in the safe operating area of the tubes. I need to check the notes that I made on the circuit diagram.

 

From memory, I have replaced the cathode resistors, bypass capacitors and coupling capacitors to enhance the performance of the amp.

 

Regards,

 

 

This was the message from the seller. 

 

I am happy now that I can use this amp with the 240v power. Would you guys advice anything else apart from this to make sure I have to worry about ??

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The seller is referring to the B+, the anode voltage.

Almost more important for tube life though is the filament voltage. I would want to know that the filament voltage of all tubes is within the specifications of the tubes.

One could assume that the autotranformer reduces the voltage for all of the power supplies but we all know what assumptions can lead to. 

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