Pierrick59,
You are based in Europe?
There are European sources for transformers - possibly will save on the shipping costs?
You are based in Europe?
There are European sources for transformers - possibly will save on the shipping costs?
I use them dual mono when 400 is called for. 6L6 or Zen will have a better idea. I always ,err, on the high side. All are greedy here.
I ended up going with the antek 4218 for 17 dollars extra. I also think the antek 4224 would also work. Same price. Need secondaries between 18v to 24v. The question gets asked often on this thread!
https://www.antekinc.com/as-4218-400va-18v-transformer/
https://www.antekinc.com/as-4224-400va-24v-transformer/
Hope that helps!
https://www.antekinc.com/as-4218-400va-18v-transformer/
https://www.antekinc.com/as-4224-400va-24v-transformer/
Hope that helps!
Heard talk of the higher output V may force you to run less bias???
The transformer unloaded output voltage can rise 5%-10% from rated full loading.
A higher VA rating transformer will result in a higher output voltage for a given loading.
So the higher voltage means the circuit needs lower current for a given power dissipation.
A higher VA rating transformer will result in a higher output voltage for a given loading.
So the higher voltage means the circuit needs lower current for a given power dissipation.
I mean I don’t want to split hairs here but I assume that if @Lewisknox is building a simple stereo F5M, then it shouldn't matter correct. Higher VA rated trafo means the trafo outputs more voltage and you will need less current to bias. Plus I think there is a little bit of headroom built into it. I am new to this and I have been corrected on erroneous info before.
Basically it's what you have at hand to use.
NP's paper talks of using the 24 V Antek but links to the 18V.
It' would be a matter of selecting more heatsink (bigger case) to run at higher bias as he discusses. He lists cases in the paper. If you can't Zen's helper would work.
NP's paper talks of using the 24 V Antek but links to the 18V.
It' would be a matter of selecting more heatsink (bigger case) to run at higher bias as he discusses. He lists cases in the paper. If you can't Zen's helper would work.
Toroidy is well reputed; many of the diyAudio members have used Toroidy for their projects.
Not sure - Toroidy units might be built to order. For commercially available off the shelf options, TME is also a source based in Europe.
^ no worries. More trying to understand a little bit more of the technical side of things. I discussed it with chat gpt, just for fun.
For a 400VA transformer with 18V secondaries, a very light load would typically be considered anything significantly less than the transformer's rated capacity. Since VA is the product of voltage and current, you could calculate the approximate load in terms of current by dividing the VA rating by the voltage.
In this case:
\[ Current = \frac{VA}{Voltage} = \frac{400}{18} \approx 22.22 \, A \]
So, for example, a very light load might be something like 5-10% of the rated capacity, which would be around 2.2 to 4.4 amps.
For a 400VA transformer with 24V secondaries, the calculation for a very light load would be similar. Let's do the math:
\[ Current = \frac{VA}{Voltage} = \frac{400}{24} \approx 16.67 \, A \]
So, a very light load for this transformer would be around 5-10% of its rated capacity, which translates to roughly 1.67 to 3.33 amps.
For a 400VA transformer with 18V secondaries, a very light load would typically be considered anything significantly less than the transformer's rated capacity. Since VA is the product of voltage and current, you could calculate the approximate load in terms of current by dividing the VA rating by the voltage.
In this case:
\[ Current = \frac{VA}{Voltage} = \frac{400}{18} \approx 22.22 \, A \]
So, for example, a very light load might be something like 5-10% of the rated capacity, which would be around 2.2 to 4.4 amps.
For a 400VA transformer with 24V secondaries, the calculation for a very light load would be similar. Let's do the math:
\[ Current = \frac{VA}{Voltage} = \frac{400}{24} \approx 16.67 \, A \]
So, a very light load for this transformer would be around 5-10% of its rated capacity, which translates to roughly 1.67 to 3.33 amps.
Papa's article mentioned +/-24V rails. For that 2x 18VAC transformer secondary voltage is about right.
With 2x24VAC secondaries you're probably looking at about +/-30V under load.
With 2x24VAC secondaries you're probably looking at about +/-30V under load.
Ah, I've rechecked the updated article and realised that the product shot I was looking at/thinking of is the old board. I was doubting my ability to count for a minute there. There are indeed 5 + 1 thermistor positions on the new design.😅 Thanks for setting me straight.
Good to have the thermistor question nailed down, too. I was going to go for the Ametherm SG40, but to be honest the lack of consistency between data sheets makes it difficult to compare to the SL22 1008 directly beyond the one or two specs.
In summary, I'll have what everyone else is having.
This is correct last I ordered with them (2022). They have standard specs to choose from, but then the order is handed to production.
Now this begs the question of what we just ordered. If we just ordered what is thought to be the updated boards why is the picture still showing the old board up for sale this minute with 8 remaining? For that link.
How will the thermistors be provided in which kit? The Essentials or Completion. If we ordered only the Essentials will the Completion kit now have to be considered requisite and ordered?
Can you add an additional pair(s) of output mosfet along with the 0.47 resistor to lower dissipation per device, or will this muck things up?
Regards, Vinay
Regards, Vinay
My understanding is this...
The Essentials Kit contains the updated board as per the note on the listing:
"3 May April 2024 update: This kit contains the updated version of the power supply board, which has separate thermistors for each channel. This allows for less noise and can work with higher current than the previous version. If you purchase one of the completion kits see the note about needing 2 more thermistors. If you are wanting to build dual mono supplies, please note that separate power supply kits will be coming in the near future."
So it's just an old photo, which is fair enough - nice photos can be a pain to organise. Might be helpful if the above text on the page specified the version number of the updated board, in leiu of an updated photo, as then we can just compare the version number to the one on the board in the photo and know where we're at.
The thermistors will be provided in the updated Completion Kit, which is apparently a month away:
"The next batch produced will include the extra 2 thermistors."
If you ordered from the current (just sold out) batch, they can send you the extra thermistors if you're in the US:
" If you live in the USA, email the helpdesk and we'll send them to you for free, though it might take a little longer than if you ordered them yourself."
twofires:
That answers my muddy questions very well. I just ordered the parts before knowing this from Digikey and was wondering what I should do now before the 'second' kit arrives. More parts for the spares.
Do you think the board 5) Therms are a different value then the 1) ground lift Therm.?
That answers my muddy questions very well. I just ordered the parts before knowing this from Digikey and was wondering what I should do now before the 'second' kit arrives. More parts for the spares.
Do you think the board 5) Therms are a different value then the 1) ground lift Therm.?