Can my AU-D907 Limited be made 120v

[ryangeorgas]

I've been using this AU-D907 Limited with a Sanyo step down transformer which works fine. It's a fantastic sounding integrated. The unit is supposedly very similar to the AU-919. However there is no voltage selector next to the transformer like there is in the 919.

I happen to also have an AU-919 with burnt outputs. Could a competent tech transplant the 919 transformer(s) into the AU-D907 limited? Would it require a transplant of all five power supplies?

I admit there is probably no point in doing this except for vanity. I would like to hear and own the only 120v AU-D907 Limited in the world

 

[bolero]

I would repair the AU 919 & use it/sell it

And keep the D907 stock

 

[Dorian]

they are practically the same devices, you can move transformers, and you can also move output modules without any problems

 

[Hyperion]

I am in the repair/recondition each one as it is camp, don't make two Frankestein amplifiers out of them. Swapping the transformers will require an above average technician - why not utilise him to repair/recondition the unit(s).

 

[Sui-Yogi]

In my opinion, I’m a hobbyist and not a tech I would made a new torodial transformer,
audio-grade and make the swap. You can read articles on the internet, signed by engineers, that a step down transformer is not a “solution with out consequences”

I do not know if it matters but the secondary’s for the power amp in the 907 limited are
41v-0-41v when for the 919 is 39v-0-39v ……
again I do not know if this 2V difference is something to be concern about .

I’m using my 907 Limited with a step down transformer but I hope I would have spend the money for an audio-grade torodial.

 

[GrisPato]

In my opinion, I’m a hobbyist and not a tech I would made a new torodial transformer,
audio-grade and make the swap. You can read articles on the internet, signed by engineers, that a step down transformer is not a “solution with out consequences”

I do not know if it matters but the secondary’s for the power amp in the 907 limited are
41v-0-41v when for the 919 is 39v-0-39v ……
again I do not know if this 2V difference is something to be concern about .

I’m using my 907 Limited with a step down transformer but I hope I would have spend the money for an audio-grade torodial.

Mhhh, although I agree with you in absolute terms.
I don't think a properly overdimensioned autotransformer Stepdown will hurt noticeable.
An autotransformer has near perfect regulation, meaning it will practically not drop in output voltage under serious load. So when double to triple the VA !
With an isolation transformer this will be different. Of course when the autotransformer fails you practically blow up your amplifier when it is 240-100.
Second, Sansui is known for making excellent transformers so to replace it will not come cheap, can even be you loose more in quality.
Interested what articles you found. I investigated heavenly before starting to buy JDP and did not encounter good information except mostly biased opinions. Yes I don't believe someone just because he is an engineer in title. His argumentation has to show he knows what he is talking about.
Is for me the same as the " toroidal is always better then EI transformer", a lot of bias.

 

[Al Casey]

In my opinion, I’m a hobbyist and not a tech I would made a new torodial transformer,
audio-grade and make the swap. You can read articles on the internet, signed by engineers, that a step down transformer is not a “solution with out consequences”

Some purists claim that having multi taps on the primary, impact the sound of the audio gear. Others claim that vintage transformers sound better than the newer. IMHO, it’s subjective because we hear music differently.
I never heard about the consequences of using step up, step down transformers;
i would be grateful if you could shed some light. I always thought that having enough power reserve and a fairly silent step up/down transformer were the requirements for a trouble-free performance.
Using a toroidal can be a solution, if there’s enough space in the amp. If memory serves, I think you have a custom-made toroidal; how did you address the switch-on inrush current issue?

 

[Sui-Yogi]

“Consequences” might not be the right English word to use , so one’s again sorry for my English !
I’m using a step-down transformer( toroidal)to plug in my AU-907 limited and I have no issues whatsoever But what I’m saying is that using a step-down is not the same using the mains from your house socket .
Here is a nice video from someone I follow in YouTube that explains in simple English a lot of electronic stuff ,at this video he addresses the step-down transformers “issues”: size-buzzing-heating . Of course you can find articles that opinions are sifting (a lot in DIY forum by “respectful” members) and all I’m saying is that the “solution” is not coming trouble-Free, one of the major issues in the auto-transformers is what @GrisPato is mentioning above.
An other one is the fact that this “small industry” converting your power is most likely near to your sensitive units and your speakers.

About the switch/on incoming current rush, I haven’t address it. The units with multiple primary switches are using the same part-number switch .
About the size of the toroidal is not a problem,
If you are replacing a toroidal with toroidal you just measure the dimensions and order the same, as long as it’s an audio-grade.
The problem is replacing an EL transformer with toroidal, most likely the toroidal at the same VA will be bigger in diameter, as far as my research has gone .

 

[DB-7]

I also agree. Get the 919 repaired. It's worthy of it.
I'd also leave the D907 alone and stick with the step down. In my opinion modifying would de-value it.
At least you are cautious enough to use the step down. I read alot where people say it works fine on 120v . (Edit: not something I would ever do). I have nixed several purchases because people cant prove they have always used a step down on JDM 100v units. Tell tale sign is when they wont sell the step down with the unit, even when you offer full price for the step down.

 

[ryangeorgas]

The D907 shipped to me from Japan so it has probably been run at 100v. It doesn't appear to have been serviced which is why I'd like a tech check it out regardless. I sure don't want to lose any output devices.

I'm sympathetic to the argument that a stepdown effects the sound. Just knowing it's there makes me question if it's different than wall power which makes me perceive the sound differently. Does that make sense? Also I'm only using a Sanyo TSD-11u while the TSD-15u is more recommended on this forum. The TSD-15u costs $450.

I look at preserving originality in audio equipment the same as with classic cars. If I can't run it on leaded gas (100v) then I'll install hardened valve seats (919 transformer) to keep it as original as is practical. I'm the type that only wants my power supplies recapped

Half of the output transistors are bad on the 919 so I can keep it for spare parts. If I had OE output replacements I would get it fixed. Having it fixed now with different outputs would cost as much as it's worth because it's hard to work on. If the value keeps climbing I can restore it in the future to sell. I'm not that interested in owning a 919 with non-stock outputs especially since I have an all original D907

I'm glad to see ARGOU has already explored this, it's very helpful. Now when I pay someone to go into the D907 I have some knowledge to discuss what route to take

 

[Al Casey]

I read alot where people say it works fine on 120v .

This instant gratification shortens the life of the transformer and may affect the proper functioning of the PSU.
Bought a Sansui amp a few weeks ago, The transformer was over-baked (no exageration), the black paint was peeling off, melted and discoloured label, because the previous owner used the amp on 120v for quite some time. Plugged into a 100v step-down transformer, there was a mechanical buzzing noise that could be heard a few meters away.
Thanks to @GrisPato who spotted an original transformer on an auction site, the amp is back to normal.

If it says 100v on the tin, it’s not 120v!

Here is a nice video from someone I follow in YouTube that explains in simple English a lot of electronic stuff ,at this video he addresses the step-down transformers “issues”: size-buzzing-heating .

Nice argument which purpose is mainly to encourage people to buy from their local authorized distributors or dealers.

If the opportunity presents itself, would you rather import an audio gear from abroad, use a step-down/up transformer and save about 60% or more or buy it in your country?

 

[GrisPato]

Thanks to @GrisPato who spotted an original transformer on an auction site, the amp is back to normal.

You got the transformer! Good to have helped to save another Sansui!

 

[GrisPato]

Having it fixed now with different outputs would cost as much as it's worth because it's hard to work on.

If I had OE output replacements I would get it fixed.

Hard to work on is a little over the top. It has a lot of boards but has easy acces to them, at least in my humble opinion.
The original outputs are obtainable, or at least the correct replacements. ( Sanken TO-3)

 

[Al Casey]

You got the transformer! Good to have helped to save another Sansui!

The transformer weighs 8.8 kilos. Synchronicity or just luck, you were there at the right time and the right place. Thanks a trillion!

 

[GrisPato]

transformer weighs 8.8 kilos

Holy! It seemed to look so small.
I should have bought it!