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clay-speakers 27th July 2019 08:03 AM

Hi - I have been reading this thread with great interest.
Your transformers sound excellent.
What transformer would you recommend for the new AK4499 - 1:4 ?
The output current is rather high at 72ma.

bisesik 27th July 2019 09:13 AM

72mA is 4 times more than cores (which I am using now) can handle. 72mA of output current according to my understanding should require revising the separation between sources (preamplifiers\dacs\players\etc.) and power amplifiers (high-current devices). In other case I do not really see the benefits of using such a device for regular usage as regular DAC. I remember complaints from engeniers even to 16mA of output current from ES9018S because it was hard to implement the I/V stage in this case... And now fantastic 72mA comes! Anyway it is possible to make transformer for 72mA, but will the 4499 be really so popular\better for their owners to wish invest up to 4 time more money into i/v transformer? I think it is better to wait for the first impressions from first users...

clay-speakers 27th July 2019 12:22 PM

Thanks for your fast response.
Yes agreed 72ma is a massive amount.
I will be running the DAC in software mode so I can reduce the current.
Maybe down to 22 ma so do you think that would be suitable with your current transformers?

bisesik 27th July 2019 12:40 PM

Do you have 4499 evaluation board already? 22mA should be ok, I think. But is there any DC Voltage between IOUTL1N and IOTL1P?

clay-speakers 27th July 2019 03:02 PM

I have my own prototype board so I will check for a voltage differential between those pins.

bisesik 27th July 2019 03:32 PM

Please make the measurement during silence-file playing, because any DC-presence at pause is not very interested (it can vary and will not make any affect to the core, because there is no memory-effect in such core material). In case of AK4490 DC can be only without signal between OUT+\OUT-.

bisesik 27th July 2019 03:44 PM

But if there will be no DC in standby, then it is enough - there is no DC. Thank you.

clay-speakers 27th July 2019 09:35 PM

1 Attachment(s)
I will do the measurements tomorrow & let you know.
A bit more info.

TioFrancotirador 28th July 2019 11:26 AM

When designing trafos for ak4499 keep in my what Taramoto found for es9038pro chip:
Teramoto FINEMET Multi tap Premium Transformer ES9038 Pro DAC (2+2+2+2 : 1+1) | eBay
They found out that is better to do the summing on the output of transformer, rather than summing them at dac level and the using transformer with one pair of input.
Now, since ak4499 has 4 pairs of outputs (2 pairs per one channel) then trafo should have 2 pairs of input and one output and the same for second channel.

bisesik 28th July 2019 11:51 AM

It is a good idea, agree. But why I do not remember the similar findings from Ian for his dual mono ES9038q2m DAC?..

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