Car Amp on the desk "Pioneer GM-40" and tune level making ?

rjenkinsgb said:

eg. Those preamps are running on somewhere around 24 or 30V, arranged as positive, ground, negative; +12, 0V, -12 or +15, 0V, -15.

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So I would need the AC 110-240V to DC 24V 4 to 6 Amp converter ; as shown in the image ; But I don't see where the ground comes and goes...

Hoo non, attends ! I need a 230V AC to 12V AC right ? Is that it ?

Or ?

link ; You have to choose from the down menu the right converter.

I'll update my schematics with this in mind then.

My answer doesn't seem to have uploaded right,
Here I go again.

I searched on Ebay ;

Ouah ! another mind bend for me !

So I need 6V-0V-6V AC/DC split (or centered tap) converter to get the 12V needed.


On Ebay (link) they say "dual 12V" Does it correspond to 12-0-12 or 6-0-6 ?

My choice would go to the 50W Dual 12V ; as it will give me a little bit over 4Amp as needed.

I'll work on the schematics then.

PS. Scratch the above response of mine. I've had too much coffee today.

Sellers on ebay do not know anything about the junk they are selling and do not speeky zee Engrish so you also do not know what they are selling.
They say the preamp needs "double" 12V to 22V which in English is +15VDC, 0V and -15VDC.
The " AC 110-240V to DC 24V 4 to 6 Amp converter'" does not make the required plus and minus voltages.
Or maybe you can find a preamp designed to be powered from a single positive supply voltage.

The preamp only needs a trivial amount of power.
You could just use a separate small 12-0-12 transformer for that and the single rail 12V DC PSU for the main amp.

Or, a small DC-DC converter that takes +12V in and gives -12V out, so you have the dual supply for the preamp running from the main PSU.

rjenkinsgb said:

and the single rail 12V DC PSU for the main amp.

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Do you mean having a second power supply ?

I guess this doesn't work then ?




Let's keep it simple, but if it's possible I'd like to have one supply for both the devices.

Certainly after all the time I've looked for this little fellow : 2*12V ; 4.16A

Besides, I think I'll need help with calculation at one point (well, if you didn't understand it yet, with pretty much everything...)

- Do I have to be extra accurate regarding the power outlet's voltage , amp ? Or is it above 12V and above 4Ampwith a bit of marging. I see 13.8V going in the main Amp IC's and a 1A fuse for the power.

- I wonder, why is it written 50VA in the datasheet of this converter if it should give out exactly 12V or 24V . there's something I don't understand the "xxVA" writting, what does VA stand for ?

Okay, I'll go read some more.

The 50VA transformer is rated at 24VAC at 2A with the 12V windings in series, or is rated for 12VAC at 4A with the windings in parallel. 48VA of power either way.

Electronic circuits take only the amount of current they need, not the entire amount of current that is available. The preamp uses a fairly low current, MUCH less than 2A.

Mika said:

I wonder, why is it written 50VA in the datasheet of this converter if it should give out exactly 12V or 24V . there's something I don't understand the "xxVA" writting, what does VA stand for ?

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VA is Volt-Ampere.
It's to do with "Power factor"; how well the current a load takes aligns with the instantaneous voltage.

With a resistive load it's the same as watts; with an inductive or capacitive load, the usable wattage can be rather lower than the VA power as the current is drawn out of phase with the voltage. A capacitive load causes current to lead voltage, an inductive load makes it lag behind voltage.


I'd not go in to that for now unless you really want to; just make sure the transformer secondary winding is rated for a bit more than the maximum load current of the amp, and you should be OK with home audio gear.

After looking a bit further, i found a preamp kit on Gotronic. They have their own pre amp. Do I have to bother with "simple winding" or "double winding" as written in the datasheet ?

Also maybe I found an amp for the pioneer too. Not sure If I have to choose for the 12V or 15V . Are the 12V supposed to be the maximum available ? Because the voltage necessary is actually more around 13V on the Pioneer.

Also, the fuse amp seems te be 4A actually.

Links below, datasheet are to find under "Fiche complète" :

Preamp Kit
Preamp converter
DC converter 12V
DC converter 15V

Attached a schematic for the powers layout.

The 15V single winding transformer will not work, use the 12V transformer.
But Google Translate messed up the translation of the transformer datasheet so I do not know how to connect it for 2 separate windings.

Oops, the DC 1 *12V link wasn't the right one. I've edited it.

And what do you think about the preamp kit ?

I am also waiting on some answers from Gotronic about how the voltages come out, and what difference there is between 1 ou 2 secondary windings.

The preamp needs a center-tapped or two windings transformer. Both transformers you selected have only one winding and will not be able to power the preamp. A center-tapped or two windings transformer can produce the required two voltage polarities.

I need to see the schematic and parts list of the preamp kit to see how old it is.

Here is the only descritpion for pre-amp kit + schematic of the transformer they advise to use ( Transfo moulé 44237 2 x 12 Vac - 5 VA)

Now I see it : there is an option with two windings for the converter ...

I have send an email to ask the precise components of the pre-amp kit, as I can't find any bill of materials in the description. Some comments are saying there should be adjustments. in the devive.

If you want me to translate, i can give a try. I speak french and dutch.

My grandmother was from Holland but never spoke a single word to me in Dutch.
I learned French in school because some people in Canada are French. But I never spoke ln French to anyone.

The manual for the preamp is in English online. It shows a schematic and parts list for a modern circuit.
Here is how its 2 x 12VAC transformer is connected:

audioguru said:

My grandmother was from Holland but never spoke a single word to me in Dutch.

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It's all a bit strange in the Netherlands

My daughter lives there, and while she works at a University (where the default language is English) she also has learnt to speak Dutch - partly because it makes sense to, and partly because in the city she lives in, English isn't very widely spoken at all. When we've been over there we've not found a single member of the public who could speak English, but as it's near the German border perhaps German is the second language? - even tourist sites seem lacking in English speakers.

Once you get to Amsterdam, EVERYONE speaks English though - but halfway across the country it's more hit and miss.

English though is usually VERY important over there - my daughter's brother-in-law failed his high school English exam - and it severely limited his job prospects. He works in a clothing store, and wasn't illegible for promotion simply because he hadn't got his English qualification. He actually failed it multiple times, and eventually my daughter, and her husband (Mike - who speaks excellent English) spent considerable time helping him learn, he then passed his exam - and is now the store manager.

As far as Mika goes - I wouldn't have known he's not a native English speaker.

For those from the USA (and Canada ) you'd fit in well over there, as a lot have American accents - they watch a LOT of American/Canadian TV (and English) and it's not usually dubbed, so has the original sound track along with sub-titles if wished. So they tend to pick up American accents

In Canada and probably also in USA we have TV from England dubbed into phonetically-correct English. We say water but in English people say Wotah with a very stiff upper lip.

The French I learned in school was from France. When I went to Quebec their French is a different dialect that I cannot understand.
We have English TV stations and French TV stations but the government says everything twice (one is poorly translated) as a terrific waste of time.

A report says that the percentage of visible-minority people in Canada slightly exceeds the percentage of not visible-minority like me. Most visible-minority people in Canada are from South Asia (India) plus many who are born here.
I see many Chinese people here but their numbers are much less than I see (maybe they hide from the count?).

Nigel Goodwin said:

It's all a bit strange in the Netherlands

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Haha, yes it is ! They speak English quite okay, but also a bit of french or German.


There is this fun area near Germany, but still in Belgium, where they speak with some English-Belgium-German accent.

It's a reason for my love Languages, and thanks for the compliment I've worked hard on my English.

Audioguru , where do you live exactly ? I would once in my life like to go to the Nunavut areas, is it somewhere by you ?
They have a beautiful language.


____


I think I have the necessary components to build all of my project don't I ? I'll start on a few drawings and come back to you.

three or for questions (for starters) :

- Why is there no eaerth/gnd connection on the transformers ? Only oine for N and L ;
-The fuse between one end of the 230V and the convert of such a small Amp ? Should it be a special fuse ? What is it for ?

- Should there be distance between the converters and the pre-amp/ amp ; Should there be distance between both converters ?

I live in a suburb of Canada's largest city, Toronto which is on the north side of huge lake Ontario and USA is on the south side of the lake. Nunavut is very far north and has a few people but has many polar bears and lots of ice.

Transformers are insulated so that they do not need an earth connection.
A cheap fuse burns out instead of the wiring and/or transformer burning out if there is a fault.
The transformers can be beside each other but their magnetic field could cause hum in nearby audio wires.

audioguru said:

In Canada and probably also in USA we have TV from England dubbed into phonetically-correct English. We say water but in English people say Wotah with a very stiff upper lip.

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Except we don't speak like that - I think you're getting confused by really poor American actors supposedly speaking in imaginary English accents.

Mika said:

Haha, yes it is ! They speak English quite okay, but also a bit of french or German.

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My son-in-law Mike speaks Dutch (obviously), English, and can 'get along' in German and French. He 'may' speak Indonesian?, as he's quarter Indonesian (his Grandmother), but it's never been mentioned.

Dutch Universities seem to run mostly in English, and at Chemalot (where my daughter spent a year as an Intern) the default language on the entire site is English - generally any science based facility tends to run in English, as it's the International language of Science.

There is this fun area near Germany, but still in Belgium, where they speak with some English-Belgium-German accent.

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My daughter and a load of friends went to see 'A Good Day To Die Hard' (the one set mostly in Russia) at a cinema in Belgium - and the film was in the original English, but where you get the Russians talking instead of English sub-titles you got Dutch ones - not Belgian, but Dutch. I thought that seemed rather strange.