300B Headphone Amp

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simon
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#46 Re: 300B Headphone Amp

Post by simon »

Some interesting reading Ray thanks.

Yes I've been thinking about another DAC project, something to better my TP Buffalo 2, but don't really know where to start.

I hadn't appreciated the 1021 could also be modded with separate PSs, similar to your OEM version. A pi/isolator/reclocker/DAC stack would be quite something! And modular too, though the blog you linked suggests the reclocker is a no brainer.

Unless USB is used. But does that need an Amanero or something instead?
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Nick
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#47 Re: 300B Headphone Amp

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Unless USB is used. But does that need an Amanero or something instead?
Yes, that or one of the Xmos based boards. I have used the Amanero and it did what it said on the tin.
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Ray P
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#48 Re: 300B Headphone Amp

Post by Ray P »

With my limited exposure to the Soekris so far I would say my Soekris 1121 sounds better than my Buffalo 3SE - more natural sounding and very easy to listen to through my Noir HPA. I'm planning to try it through my 300B SE-OTL amps at the weekend.

My Buffalo3SE is no slouch either being equipped with I2S input via an isolator/reclocker and power provided by four Salas shunt regs; output stage is the Twisted Pear Legato (which serves as the HPA so I'm not really just comparing the actual DACs but the overall packages).

With the RPi I would lean towards the IanCanada isolator/reclocker board though that does cost you some flexibility having the two functions closely integrated feels like a good thing. That said, I have no doubts that the Allo boards will do an excellent job and do allow you to iteratively improve the performance. If you want USB I would go for the JLSounds board I linked to, it has better NKD oscillators and integrated isolation/reclocking and is superior to the Amanero IMO.

Probably too far away but I am planning to bring my Soekris 300B HPA to Owston.
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simon
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#49 Re: 300B Headphone Amp

Post by simon »

I was looking at the dam1921 earlier - not particularly cheap at EUR380 + 25% VAT - but it does look to have USB (there's an Xmos chip anyway) built in which would save a few quid.

http://www.soekris.dk/dam1941.html

So perhaps connect the pi via USB, and maybe add an isolator for good measure?
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Ray P
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#50 Re: 300B Headphone Amp

Post by Ray P »

simon wrote: Thu Feb 27, 2020 7:10 pm I was looking at the dam1921 earlier - not particularly cheap at EUR380 + 25% VAT - but it does look to have USB (there's an Xmos chip anyway) built in which would save a few quid.

http://www.soekris.dk/dam1941.html

So perhaps connect the pi via USB, and maybe add an isolator for good measure?
I wouldn't - I think USB from the RPi is pretty rubbish IIRC. If you want to go USB it would be cheaper to go for a 1021 and a JLSounds USB board anyway. An isolator pi hat won't help with USB either, the boards in the previous posts have been for the I2S output.

Start with the RPi and send I2S to a 1021 would be my advice, then add isolation, reclocking and a slick control interface as the opportunity/need presents itself. Don't forget the 1021 includes output buffers that will drive headphones, or you can just take the raw output to an amp or add your own buffer.
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#51 Re: 300B Headphone Amp

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Simon, I've just sent you a PM.
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Nick
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#52 Re: 300B Headphone Amp

Post by Nick »

I think USB from the RPi is pretty rubbish IIRC
Don't know, i am not even sure what it could matter as long as its using USB Audio 2 and Async, the receiver should do the heavy lifting and use its local clock to generate the i2s timing. In the dac I built I used the Amnaero board into a ISO7240 isolator (and that also let me switch between the spdiff input receiver and USB).

Given the care that seems to have been put into the r2r boards I would expect a good USB interface.
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#53 Re: 300B Headphone Amp

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It's been a while since I paid much attention to RPis but I seem to remember the USB port was very 'noisy' because it shared stuff with the ethernet side and it did degrade audio performance IIRC? Maybe your right that a decent USB receiver would mitigate this as you describe. Following an Amanero with an isolator is pretty standard practice but I would be inclined to reclock the data on the clean side of the isolator too; in my experience reclocking makes a worthwhile improvement in SQ, though on the Soekris it may be less important given that it reclocks itself between the FPGA and the resistor arrays.

Anyway, if you plan to use a RPi as your renderer, as the Soekris DACs accept I2S it would seem simpler just to take the I2S data stream straight from the RPi to the DAC instead of out and back in via USB. I've used USB on this HPA project because I want the option of using a smartphone as a digital player (using the USB Audio Pro app and a USB OTG connector), otherwise I would have used my usual BBB approach.

All of the Soekris DACs allow you to select inputs, from the full suite on the 1921 or just between spdif/optical and I2S on the 1021/1121.
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simon
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#54 Re: 300B Headphone Amp

Post by simon »

There's certainly a lot to recommend the 1021 with IanCanada combined reclocker and isolator. But the 1921 would allow easy comparison between I2S and USB. You pays yer money and makes yer choice I guess.
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Ray P
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#55 Re: 300B Headphone Amp

Post by Ray P »

Don't forget Soekris do finished DACs too, for example;

http://www.soekris.dk/dac1321.html

http://www.soekris.dk/dac1421.html
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Ray P
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#56 Re: 300B Headphone Amp

Post by Ray P »

If it's of interest to anyone there's a Soekris dam1021-05 board listed on eBay at the moment - might be worth a cheeky offer?

https://www.ebay.co.uk/itm/Soekris-dac- ... 1438.l2649
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Ray P
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#57 Re: 300B Headphone Amp

Post by Ray P »

Frustratingly, so near but yet so far; I'm almost ready to hook this thing up but stalled waiting for just a couple of parts to be delivered after UPS cocked up the original delivery.

I installed and tested two of Andrew's DHT filament supplies last weekend. All I have left is to finish and test the Maida regulator for the B+ supply.
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Ray P
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#58 Re: 300B Headphone Amp

Post by Ray P »

Ooooh, I've just had notification that I have a UPS delivery scheduled for tomorrow so with a bit of luck and if they maintain their usual delivery performance I'll get the parts I need on Tuesday or Wednesday - just in time for the long Easter weekend.
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#59 Re: 300B Headphone Amp

Post by Ray P »

UPS has delivered a Digikey box so hopeful of some progress this weekend.
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#60 Re: 300B Headphone Amp

Post by Ray P »

A successful day - I now have a full set of power supplies installed and tested.

Just have to hook up the amplifier modules now, maybe this evening if I'm not too tired - I don't want to make a mistake at this stage.
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