Advice On Using Stereo From Usa

[junglechef]

I have an American Adcom brand stereo. It's 1000 watts 120 volts and 50-60 hz , . I know I will need to get a converter to 220v and have read that one rated more than 1000 watts is recommended. Also I used to plug it into the preamp which says unswitched 800VA max, AC 120V, 50-60 hz but does not have a power. Do I need two convertors? Anybody have anything to add before i spend the money and plug her in.

[ThaiWx]

One, 1000 watt transformer should be enough to cover both the main stereo and the pre-amp. If either of the components (main stereo or pre-amp) has an outlet AC receptacle on the back you could just plug the other component in there and power the two components from the single transformer. Otherwise you could just use a multiple AC outlet from the transformer and plug the two components in this way.

If I understand you correctly , you used to plug the main stereo into the back of the pre-amp's 800VA unswitched outlet. You can still do it this way and plug the power cord of the pre-amp into the transformer, powering it all this way.

Edited June 22, 2011 by ThaiWx

[Dellboy218]

Just as a matter of interest, would that be1000W PMPO (peak music power output) which would be averaging around 60W which would be a normal power output? Stereos display so many power ratings all based on different criteria.

What mains fuse rating does it have? This will tell you the rating of the transformer you require.

[Cuban]

J What mains fuse rating does it have? This will tell you the rating of the transformer you require.

Because the amp is stamped 1,000 Watt this does not mean that it uses 1,000 Watts of electrical power from the mains.

Printed on the back will be the power rating as mentioned above 60VA etc.

If you use it with a 10Amp mains fuse in the US, to be safe you will only need a 5Amp fuse in Thailand on the feed to the transformer that you will need.

As you double the supply voltage, you half the current that is drawn.

You might consider fitting a replacement transformer inside the device with primaries wound for 220volt.

BTW I have seen US equipment killed by Thais not reading/understanding the instructions written by expats on their equipment not to plug in 110v kit in Thai power outlets.

HTH

[junglechef]

Glad I found some knowledgeable ppl here, definately more than me on this subject. Not sure what the PMPO is. It says "AG FUSE 10A AGC" and the power says 1000W Max (1000VA). It was a pretty high end system (ADCOM GFA-555 amp) when I bought it 20 yrs ago if that's any help.

Just as a matter of interest, would that be1000W PMPO (peak music power output) which would be averaging around 60W which would be a normal power output? Stereos display so many power ratings all based on different criteria.

What mains fuse rating does it have? This will tell you the rating of the transformer you require.

[OriginalPoster]

Glad I found some knowledgeable ppl here, definately more than me on this subject. Not sure what the PMPO is. It says "AG FUSE 10A AGC" and the power says 1000W Max (1000VA). It was a pretty high end system (ADCOM GFA-555 amp) when I bought it 20 yrs ago if that's any help.

Just as a matter of interest, would that be1000W PMPO (peak music power output) which would be averaging around 60W which would be a normal power output? Stereos display so many power ratings all based on different criteria.

What mains fuse rating does it have? This will tell you the rating of the transformer you require.

The GFA-555 runs class AB so at idle and relatively low volume levels it's not going to draw anywhere near the 1000VA that it says on it's UL label. And it's definitely not going to pop a 10A amp fuse l unless there's a malfunction.

As far as 1000W PMPO (peak music power output), as I recall those adcoms has a RMS power rating of around 200W into 8 ohms, so if the are able to peak out at 1000W that's got to be only on transients and most likely into less than 8 ohm loads. I'd probably hook it to a dedicated 1000W 220/110V transformer and not worry about it being too small, but I suppose that it is possible that using a bigger one might provide some marginal improvement in sound quality if you're going to be pushing the amp hard.

[sfokevin]

I would be interested in the idea of replacing the power supply!...

I presently have my Harman Kardon receiver hooked up to a warm transformer (which I assume I am paying to keep warm 24/7)...

Where in CM can a replacement transformer be purchased?

[Dellboy218]

Glad I found some knowledgeable ppl here, definately more than me on this subject. Not sure what the PMPO is. It says "AG FUSE 10A AGC" and the power says 1000W Max (1000VA). It was a pretty high end system (ADCOM GFA-555 amp) when I bought it 20 yrs ago if that's any help.

Just as a matter of interest, would that be1000W PMPO (peak music power output) which would be averaging around 60W which would be a normal power output? Stereos display so many power ratings all based on different criteria.

What mains fuse rating does it have? This will tell you the rating of the transformer you require.

The GFA-555 runs class AB so at idle and relatively low volume levels it's not going to draw anywhere near the 1000VA that it says on it's UL label. And it's definitely not going to pop a 10A amp fuse l unless there's a malfunction.

As far as 1000W PMPO (peak music power output), as I recall those adcoms has a RMS power rating of around 200W into 8 ohms, so if the are able to peak out at 1000W that's got to be only on transients and most likely into less than 8 ohm loads. I'd probably hook it to a dedicated 1000W 220/110V transformer and not worry about it being too small, but I suppose that it is possible that using a bigger one might provide some marginal improvement in sound quality if you're going to be pushing the amp hard.

Yup.thats what I was trying to get at. Quite often the peak music power (The sound output) is quoted at some ridiculous level like 1000W for a machine that can also run on 'D' cell batteries. They will justyify this by watching an oscilloscope that shows an output at that level for 1 micro second. You Obviously do need the 1kW or even, at that fuse level a bit more 1.2kW depending if anything else is going to run through it but as mentioned that will only be at max output which would be pretty deafening! For the 220v side on a 1kW it will be about 5A. I know Amorn do sell some step down transformers but whether they sell anything that big...................

[junglechef]

If this is any more help

[misterkeeperofthereef]

Hello. I bought a Adcom GFA-555 Pro here in Thailand that is wired 220 volt from the stereo shop on the 3rd floor Central Plaza . The gentlemen there seemed pretty knowledgeable and would be able to direct you to a solution .

[Dellboy218]

Thats some amp isn't it! My comments from the previous email still stand. 1000VA, 1000/220v = 5 Amps. so you need to look for a 1000VA stepdown transformer which will probably have the correct fuses already fitted.

The problem of replacing the internal transformer is knowing what the secondary voltages/ratings of the original transformer are. The chances are they are not going to be ''off the shelf''. I can tell you that it has 2 secondary windings and you can find the service manual parts list / schematic here http://akdatabase.org/AKview/albums/userpics/10004/Adcom%20GFA-555II%20Service.pdf but it does not tell you the ratings of the secondary windings. You would have to check that yourself, it is usually marked on the transformer itself.

Same goes for a Harman Kardon receiver, you will have to get the spec of that transformer with regards to the secondary winding(s) before you can think about replacing it unless you go back to the makers or their reps of course.

[ThaiWx]

Glad I found some knowledgeable ppl here, definately more than me on this subject. Not sure what the PMPO is. It says "AG FUSE 10A AGC" and the power says 1000W Max (1000VA). It was a pretty high end system (ADCOM GFA-555 amp) when I bought it 20 yrs ago if that's any help.

Just as a matter of interest, would that be1000W PMPO (peak music power output) which would be averaging around 60W which would be a normal power output? Stereos display so many power ratings all based on different criteria.

What mains fuse rating does it have? This will tell you the rating of the transformer you require.

The GFA-555 runs class AB so at idle and relatively low volume levels it's not going to draw anywhere near the 1000VA that it says on it's UL label. And it's definitely not going to pop a 10A amp fuse l unless there's a malfunction.

As far as 1000W PMPO (peak music power output), as I recall those adcoms has a RMS power rating of around 200W into 8 ohms, so if the are able to peak out at 1000W that's got to be only on transients and most likely into less than 8 ohm loads. I'd probably hook it to a dedicated 1000W 220/110V transformer and not worry about it being too small, but I suppose that it is possible that using a bigger one might provide some marginal improvement in sound quality if you're going to be pushing the amp hard.

Specs of this amp do show it will deliver just over 200w into 8 ohm speakers as you say and around 1000w capable using 2 ohm speakers. http://www.bobbyshred.com/infinity/adcom555.html

[HarryPalmer]

According to the schematic provided by Dellboy, the GFA-555 has dual 120v primaries wired in parallel, so it should be easy to wire them in series for 240v (if you know what you're doing).

[ThaiWx]

According to the schematic provided by Dellboy, the GFA-555 has dual 120v primaries wired in parallel, so it should be easy to wire them in series for 240v (if you know what you're doing).

Good point. Could take the amp and pre-amp (assuming it's strappable as well) down to a competent electronics/stereo shop and have them re-strap them both for 220v. Print out the very bottom of this schematic and bring along. - http://www.audiolabg...5II%20Adcom.pdf . No step down 1000 watt transformer to worry about this way.

Edited June 23, 2011 by ThaiWx

[Dellboy218]

According to the schematic provided by Dellboy, the GFA-555 has dual 120v primaries wired in parallel, so it should be easy to wire them in series for 240v (if you know what you're doing).

Well spotted My. Palmer, I must have had blinkers on! Next question will be for Jungle chef to find out the model number of that preamp!

[junglechef]

The model number of the preamp is GTP-500 . But to be honest this is getting way over my head. Finding someone who knows what they are doing can be difficult here sometimes for me esp. figuring out between all those who say '''yeah yeah, no problem" and know and those who don't. I appreciate all the posts and will continue reading and learning and with a bit of "chok dee" hope to be blasting tunes soon!!

[Dellboy218]

The model number of the preamp is GTP-500 . But to be honest this is getting way over my head. Finding someone who knows what they are doing can be difficult here sometimes for me esp. figuring out between all those who say '''yeah yeah, no problem" and know and those who don't. I appreciate all the posts and will continue reading and learning and with a bit of "chok dee" hope to be blasting tunes soon!!

Good Day again

Unfortunately finding a downloadable diagram of the GTP-500 is proving a trifle harder, no matter.

I will attempt to explain and apologies if a granny and sucking eggs come into it.

One of the first components the mains power comes to in your stereo is the mains transformer. This will alter the voltage to a level that is required. A transformer has a primary, where your mains comes in and the secondary, where it comes out. The two windings are physically isolated and linked by magnetic field.

What Mr. Palmer spotted on the diagram and which I should have done was that primary consists of 2 seperate windings. these are both rated with 0v at one end and 120v at the other. These can be wired in two ways. In parallel to achieve an input capability of 120V and double the current of a single primary, or they can be wired in series to achieve a 0-240V and single current capability. The power rating remains the same, double one and halve the other.

What the diagram shows is that the transformer fitted to the amp MIGHT be capable of being wired for 220-240v operation. I say might as it might differ from the diagram. It makes economic sense for the maker as they do not have make a different model for markets outside of the U.S., they just rewire slightly what they already have.

Time to get someone to look at it and cross your fingers you might be lucky. If you are, DONT FORGET to change the fuses to half the specified value.

[OriginalPoster]

Thats some amp isn't it!

Yes, it was one helluva an amp, and though not cheap it delivered sound quality far beyond it's price point.

Back in the 80's & early 90's there are a number of amps like that. The Adcom 555 was a sort of a "budget" high end amp that was the heir apparent to the Haffler DH220. At a bit higher price-point, there also were big brutish amps with good sound such as the solid state PS Audio 200C and the hybrid NYAL Moscode poweramps. Now amps anywhere near to the same league of those cost many times more. Whenever you find one of those amps up for resale they can be a great purchase, usually they will sell for half their original price despite sounding as good as present day amps costing twice as much.

Edited June 26, 2011 by OriginalPoster

[junglechef]

Thanks one and all, it's up and running and sounding Greaaaaat!

[sfokevin]

Thanks one and all, it's up and running and sounding Greaaaaat!

So after all our great inputs what was your final setup/solution?

[misterkeeperofthereef]

Glad you got it all worked out . These are awesome amps. I owned 2 of them in Canada and had been looking for a amp here for 2 years and finally stumbled upon on at the stereo shop on the third floor Central shopping mall. It is a GFA-555 Pro amp and a GFP-555 pre amp and they are in premium condition and were wired 240v from factory . I paid 18000 baht for the pair . They have started manufacturing these amps again in mid 2010 with a price tag of $ 1295.00 US dollars . Any of you guys know where to find some decent woofers ?

[junglechef]

Bought a 1000W transformer. After past experiences here have learnt that I must manage my projects and don't know enough about rewiring to do that or even to figure out if they do. I appreciate everyone help who suggested this solution and the others too! Thanks again.

Thanks one and all, it's up and running and sounding Greaaaaat!

So after all our great inputs what was your final setup/solution?

[62strat]

If possible I would buy a very good quality transformer with line conditioning as some audio amps are bad with a different cycle line noise, 50 cycle filters for 110V .and 60 for most 220V ...maybe check the output voltage and supply voltage (outlet) with a meter, A little higher is fine as the load will drop the voltage a little....

[bamboozled]

Two questions, please. As I also have a 120 v amp, where did you buy your transformer? Also, this stereo shop at Central Airport Plaza, do they deal in speakers as well? I have a great pair of Infinity's, one of which is sounding a bit funky, seems the tweeter has gone past it's "best if used by" date so I'm looking to have it looked or to buy a new tweeter. Would that be a good place for this purpose? By the way, what is the effect of time on speakers? I wouldn't think it effects amplifiers so much but the materials used in woofers for example, that have to be flexible and move, I would suspect that over time they breakdown and become brittle, effecting sound quality and eventually ripping apart. These speakers are now about 15 years old, as is the amp. Any comments from the experts? Thanks so much, Peter.

[junglechef]

Not an expert just the OP. I bought my transformer just outside Icon Center, forget the name but right to the left of the front door. I went to that shop in Central Plaza but was dealt with rudely. Told I could only listen to jazz on a pair of speakers I was thinking of buying (they had lots of other music) and other such attitude so I just left.

Two questions, please. As I also have a 120 v amp, where did you buy your transformer? Also, this stereo shop at Central Airport Plaza, do they deal in speakers as well? I have a great pair of Infinity's, one of which is sounding a bit funky, seems the tweeter has gone past it's "best if used by" date so I'm looking to have it looked or to buy a new tweeter. Would that be a good place for this purpose? By the way, what is the effect of time on speakers? I wouldn't think it effects amplifiers so much but the materials used in woofers for example, that have to be flexible and move, I would suspect that over time they breakdown and become brittle, effecting sound quality and eventually ripping apart. These speakers are now about 15 years old, as is the amp. Any comments from the experts? Thanks so much, Peter.

[bamboozled]

Thanks Junglechef. I'm pretty close to Icon so I will stop by there and easy enough to go to Airport Plaza... but hopefully they will be less rude.

Not an expert just the OP. I bought my transformer just outside Icon Center, forget the name but right to the left of the front door. I went to that shop in Central Plaza but was dealt with rudely. Told I could only listen to jazz on a pair of speakers I was thinking of buying (they had lots of other music) and other such attitude so I just left.

Two questions, please. As I also have a 120 v amp, where did you buy your transformer? Also, this stereo shop at Central Airport Plaza, do they deal in speakers as well? I have a great pair of Infinity's, one of which is sounding a bit funky, seems the tweeter has gone past it's "best if used by" date so I'm looking to have it looked or to buy a new tweeter. Would that be a good place for this purpose? By the way, what is the effect of time on speakers? I wouldn't think it effects amplifiers so much but the materials used in woofers for example, that have to be flexible and move, I would suspect that over time they breakdown and become brittle, effecting sound quality and eventually ripping apart. These speakers are now about 15 years old, as is the amp. Any comments from the experts? Thanks so much, Peter.

[Dellboy218]

Thanks Junglechef. I'm pretty close to Icon so I will stop by there and easy enough to go to Airport Plaza... but hopefully they will be less rude.

Not an expert just the OP. I bought my transformer just outside Icon Center, forget the name but right to the left of the front door. I went to that shop in Central Plaza but was dealt with rudely. Told I could only listen to jazz on a pair of speakers I was thinking of buying (they had lots of other music) and other such attitude so I just left.

Two questions, please. As I also have a 120 v amp, where did you buy your transformer? Also, this stereo shop at Central Airport Plaza, do they deal in speakers as well? I have a great pair of Infinity's, one of which is sounding a bit funky, seems the tweeter has gone past it's "best if used by" date so I'm looking to have it looked or to buy a new tweeter. Would that be a good place for this purpose? By the way, what is the effect of time on speakers? I wouldn't think it effects amplifiers so much but the materials used in woofers for example, that have to be flexible and move, I would suspect that over time they breakdown and become brittle, effecting sound quality and eventually ripping apart. These speakers are now about 15 years old, as is the amp. Any comments from the experts? Thanks so much, Peter.

That would be Amorn, they also have stores in Hangdong Road Big C and what was Carrefour but that is their biggest one in town (that I am aware of)

Edited July 7, 2011 by Dellboy218

[damole]

There's a great electronic shop called Kiti Electronic at 193/31 Chang Puek, tel 053-221463, it's on the corner of a road that leads to Tannin market. I bought a mini toroidal transformer there to build a new power supply for my Audio Alchemy Dac-in-a-Box that died during a mini flood in my condo. It's the only place I found that had a decent selection of toroids. I tried at Amorn and then the row of elecronic shops on Ratchawong road (Kasem shop near Warawot)and was put on to this place by the guys at Trigger sound, the shop on the corner opposite the Esso petrol station that sell/rents amps and PA speakers.

--damole

[bamboozled]

Thanks Damole. By the way, what the heck is a "toroidal"? Is that a brand name? I'm just looking for a decent step-down transformer. I have one at the moment but I don't really trust it. I expect to have problems with it and/or the stereo if I use it a lot.

There's a great electronic shop called Kiti Electronic at 193/31 Chang Puek, tel 053-221463, it's on the corner of a road that leads to Tannin market. I bought a mini toroidal transformer there to build a new power supply for my Audio Alchemy Dac-in-a-Box that died during a mini flood in my condo. It's the only place I found that had a decent selection of toroids. I tried at Amorn and then the row of elecronic shops on Ratchawong road (Kasem shop near Warawot)and was put on to this place by the guys at Trigger sound, the shop on the corner opposite the Esso petrol station that sell/rents amps and PA speakers.

--damole

[OriginalPoster]

Thanks Damole. By the way, what the heck is a "toroidal"? Is that a brand name? I'm just looking for a decent step-down transformer. I have one at the moment but I don't really trust it. I expect to have problems with it and/or the stereo if I use it a lot.

it's a doughnut shaped transformer; sometimes used in some audio applications because they provide some degree of self-shielding and hence are less likely to induce hum in a stereo system. But he's taking about a transformer used in an audio component's power supply, not a transformer to step down from 220V to 110V.

Edited July 8, 2011 by OriginalPoster