Preamp Q8 Desktop DAC Preamp Development Log

[Charles]

I've heard Bluetooth being used in mesh and/or piconet configuration; enabling wireless multi-device connectivity.
Would this be an in-demand or a useful feature for those who'd rather not run wires for multi-channel/multi-speaker setup?
Personally, I'd choose more USB ports over multiple SPDIF interfaces.
Is the current design include simultaneous (XLR+RCA) outputs? Should it?
Can the analog inputs routed thru the BT circuit for ADC function and routed to one of the USBs?
Orange volume knob has always been cool but that little edge indent is impossible to see or feel... as always...

Do you want multi device wireless output?
We support XLR+RCA synchronous output;
Our preliminary design of the analog input circuit is to use an analog circuit throughout the entire process without going through an ADC circuit, in order to maintain the purity of the signal;
What does the edge indentation of the orange knob mean? Can you please describe it in detail?

 

[Charles]

Hi,
The Q8 looks good, but I have not read about any software control interface(s). Is this to be via BT, or (preferably) via LAN/Wifi ?
If I have missed these details I apologise!

We currently do not support LAN/Wifi connections, but we support USB connections to our software. Our software is still under development and may be connected through online upgrades in the future;

 

[Charles]

Your rendering shows what appears to be XLR balanced inputs, but they're not listed on the spec sheet. Are they planned?

Love the adjustable HPF. Are you looking at a 12- or 24-db/octave slope? Will this feature make it onto any other Fosi products?

We have finally decided not to include XLR input and only keep three RCA inputs, but there will be RCA and XLR outputs, as well as SUB RCA output. However, we have HPF function and the slope has not been determined yet. What would you like? We will plan these functions according to everyone's needs.

 

[Charles]

Charlese, I would like the project to include a trasparent line out, not affected by volume control or other active stages, to which I could connect a second independent amplifier. This would allow me to eventually add another pair of speakers in strategic positions within my setup, providing greater flexibility in listening or expanding the soundstage in larger or more complex environments.

We have a direct function, but do we need to input sensitivity adjustment function? Isn't this generally compatible?

 

[Charles]

Would this have a Pure Mode/Direct Mode/Defeat function, to disable all internal processing, for near zero latency? It would be perfect for Studio Purposes as well if thats the case.

Could you please explain the subtle differences between these three "functions" in detail?
Thank you.

 

[Charles]

Hello Charles, this is a great design. I already ordered the ZP3. With this new product, can you make the high and low pass filters adjustable? Like the Emotiva PT2 pre amp? About power supply, I know it's not ideal for everyone, but it could be external and leave the option for normal or linear. I do believe the linear one would get this product to the next level

Our final plan is to remove the LPF function and retain the HPF function, so that the SUB RCA output is actually a full frequency signal, and everyone can choose whether to connect a subwoofer or other devices.

 

[Charles]

Is that confirmation that the screen will have an indicator of the current volume level (unlike the unfortunate blind ZP3 volume control)? That is the most important thing for the screen to display, IMO. Should be large and readable from a distance. Everything else is secondary.

How big do you think the screen should actually be? What is the required volume number? Is there a specific size you want?

 

[Charles]

Charlese, I would like the project to include a trasparent line out, not affected by volume control or other active stages, to which I could connect a second independent amplifier. This would allow me to eventually add another pair of speakers in strategic positions within my setup, providing greater flexibility in listening or expanding the soundstage in larger or more complex environments.

We have a mode that is completely direct, without going through any internal circuits;

 

[Charles]

Please share the model DAC chips in the Q8. I would like to know how the DACs will handle the XLR and RCA outputs. Thanks,

AK4493SEQ

 

[Charles]

Thank you but can I suggest the auto screen shutdown option has a much shorter timer than two minutes? In a scenario where I am watching TV and I turn up the volume up or down, then I would expect the display to come on and show the changes, and then no more than 10 seconds after the last command being sent the display should shut down again. Two minutes is way too long just to acknowledge a volume or input change etc. Thanks, product is looking great.

Sure, we have only set a single duration for now. We will add other durations in the future. What other durations do you want?

 

[Charles]

I've looking for similar products in order to be able to centralize my sources.

My ideal setup goes like this: Turntable + CD Player + Streamer. Turntable goes to external phono preamp, streamer goes to external DAC through optical. Also TV goes to external DAC though HDMI or optical 2. And then, everything goes through one RCA output to speaker amplifier, and another RCA output to headphone amplifier.

I consider FiiO K7, SMSL RAW MDA1, SMSL DL100, Fosi P4... everyone has one defect or another. For example, the SMSL DACs are almost perfect, but they don't have RCA input to passtrough the internal DAC and use them as a preamp. FiiO K7 has RCA and digital, but doesn't have HDMI nor a second optical, so I would need to buy a TOSLINK selector. Fosi P4 is perfect as a source selector, but it does have just one RCA output, and none headphone amplifier. I know Topping has some headphone amplifier models with RCA passthrough, but I would prefer to have those audio chains separated. Fosi ZP3 looks ALMOST perfect to centralize sources while using another DAC, but it has just one RCA output! How do I add the headphone amplifier if my speaker amplifier doesn't have XLR? RCA is still the most common used connection, besides XLR popularity.

Fosi Q8 looks almost perfect, but I think it would be benefited if you consider some things already mentioned in this thread:

1. You should add another RCA output. 2 speaker amps, 1 speaker amp and 1 headphone amp... it's not expensive or complex. Having the option to listen through headphones for all your sources it's not just amazing, but essential. Having kids or living on apartment, sometimes at night you can't make too much noise. Headphones are a necessity.

2. Don't add a phono preamp input. Really, don't do it. There's two type of people who use a turntable: new ones and old ones. New ones has a turntable with built in phono, and if they don't, they already have an external phono that's probably better. Old ones definitely have an external phono. You already have Fosi X5!

3. Keep bluetooth, LDAC and aptX adaptive compatible. It won't be useful to me, but it's a standard today for this type of products. You would be surprised if you know how many audiophiles still uses bluetooth because it's convenience. If you promote that your bluetooth connection pass through the AK4993 DAC, you will have another consideration to buy Q8.

4. You should add another optical input. For example, if you want to use TV + gaming console, TV goes through optical and gaming console (Xbox Series X, for example) goes through HDMI. You want to avoid using TV as an intermediary through console and DAC, because of delay. So, considering that, where do you connect your streamer, then? Second optical! Same applies for a blu-ray player or even CD Player that for some reason doesn't have coaxial out.

5. Consider an integrated headphone amp. For me, it would make your product totally perfect. But you shouldn't make choices for one or two potential buyers. If you do, amazing, but a second RCA out would be enough.

I'll stay tuned for updates. I'm excited!

Thank you very much for your suggestion. We would like to discuss a few points with you:
1. In addition to the RCA output with HPF function, we also have a SUB RCA output (as mentioned above, if you don't need to connect a subwoofer, you can use this as a complete RCA output interface. I wonder if it can meet your needs? ）
4. Here we would like to ask you two questions: First, the game console is connected to the computer via HDMI, and then the TV is connected via fiber optic. Have you encountered any delays?
5. We may not add a headphone amplifier at the moment, but we will consider this feature for the next model.

 

[Martin Roscos]

We have a product ZD3 that meets your needs. It comes with XLR and RCA outputs, and you can use RCA to connect the subwoofer. And it comes with Bluetooth and USB input.

The ZD3 is awesome

 

[Massimo]

We have a direct function, but do we need to input sensitivity adjustment function? Isn't this generally compatible?

I'm referring to a direct line output, optionally equipped with a sensitivity control separate from main output, to allow connection to a second amplifier, with in turn makes it possible to connect two additional speakers to be strategically placed in a room. Basically, for someone who has, for example two V3 mono units and a p4 o p3, this could allow them to have two separate systems or alternatively, a four speaker setup. I hope I've made myself clear.

 

[alaperse]

We have finally decided not to include XLR input and only keep three RCA inputs, but there will be RCA and XLR outputs, as well as SUB RCA output. However, we have HPF function and the slope has not been determined yet. What would you like? We will plan these functions according to everyone's needs.

What's the logic behind XLR output but no XLR input? All chain needs to be balanced in order to avoid interference, that is the essence of balanced audio. Without XLR input, XLR output becomes decorative. Considering that, you could then take out XLR entirely and use just RCA. That would be better than using half one half the other.

 

[alaperse]

Thank you very much for your suggestion. We would like to discuss a few points with you:
1. In addition to the RCA output with HPF function, we also have a SUB RCA output (as mentioned above, if you don't need to connect a subwoofer, you can use this as a complete RCA output interface. I wonder if it can meet your needs? ）
4. Here we would like to ask you two questions: First, the game console is connected to the computer via HDMI, and then the TV is connected via fiber optic. Have you encountered any delays?
5. We may not add a headphone amplifier at the moment, but we will consider this feature for the next model.

1. Well, I think it's weird to have to prefer between a second RCA output and to have a subwoofer out, but for me, it does work. I don't have nor pretend to have a subwoofer. Is the SUB RCA output single ended (mono) or stereo? If it's stereo and the LPF can be turned off, then it works as a second output.

4. It shouldn't have noticeable delay. I haven't tried that config yet, as I don't have a DAC with HDMI ARC function.

5. As far as I can add a headphone amplifier with SUB OUT, it's fine.

 

[alaperse]

Our final plan is to remove the LPF function and retain the HPF function, so that the SUB RCA output is actually a full frequency signal, and everyone can choose whether to connect a subwoofer or other devices.

That is the best approach. Normally the subwoofer itself has it's own LPF function. The important one is the HPF for the main speakers. Of course, HPF needs to be switchable to full frequency signal, for all those who don't use subwoofer and want all the frequency into the main speakers.

 

[alaperse]

Do you want multi device wireless output?
We support XLR+RCA synchronous output;
Our preliminary design of the analog input circuit is to use an analog circuit throughout the entire process without going through an ADC circuit, in order to maintain the purity of the signal;
What does the edge indentation of the orange knob mean? Can you please describe it in detail?

Keep the analog input circuit, don't use ADC. Those who use a turntable with external phono will be grateful (including me!).

 

[masmith2]

We have finally decided not to include XLR input and only keep three RCA inputs, but there will be RCA and XLR outputs, as well as SUB RCA output. However, we have HPF function and the slope has not been determined yet. What would you like? We will plan these functions according to everyone's needs.

ok, Thanks for sharing this information. I still plan on purchasing the unit.

 

[masmith2]

AK4493SEQ

Thanks for sharing

 

[Charles]

What's the logic behind XLR output but no XLR input? All chain needs to be balanced in order to avoid interference, that is the essence of balanced audio. Without XLR input, XLR output becomes decorative. Considering that, you could then take out XLR entirely and use just RCA. That would be better than using half one half the other.

Hello, we are preparing to decode the audio signal through AK4493SEQ and select XLR output.

 

[Charles]

I'm referring to a direct line output, optionally equipped with a sensitivity control separate from main output, to allow connection to a second amplifier, with in turn makes it possible to connect two additional speakers to be strategically placed in a room. Basically, for someone who has, for example two V3 mono units and a p4 o p3, this could allow them to have two separate systems or alternatively, a four speaker setup. I hope I've made myself clear.

We have a SUB RCA, which is also affected by the volume knob and high/low frequencies. Is this interface acceptable to you? Or can you only accept a second set of RCA outputs that are completely independent of these controls.

 

[Charles]

1. Well, I think it's weird to have to prefer between a second RCA output and to have a subwoofer out, but for me, it does work. I don't have nor pretend to have a subwoofer. Is the SUB RCA output single ended (mono) or stereo? If it's stereo and the LPF can be turned off, then it works as a second output.

4. It shouldn't have noticeable delay. I haven't tried that config yet, as I don't have a DAC with HDMI ARC function.

5. As far as I can add a headphone amplifier with SUB OUT, it's fine.

It is a stereo RCA output.

 

[masmith2]

My personal request would be to have 2 optical inputs so I can run 2 digital devices into this. It is part DAC afterall

The SMSL RAW DAC1 has 2 optical inputs

 

[nmjona]

Charles I missed the last couple of days and I'm reading bad news. Removing XLR input and LPF won't work for me. Making the LPF/HPF adjustable in the same unit would have been a hit. Ask Nemo Propaganda or Zeus. Sorry I can't be happy with those decisions.

 

[nickhews]

We currently do not support LAN/Wifi connections, but we support USB connections to our software. Our software is still under development and may be connected through online upgrades in the future;

In what ways are the various inputs/outputs and other potential settings to be made/controlled? I guess some may be through use of a touchscreen, or do you intend to include a remote control that can do or mirror these things? I assume that volume control at the least will be by remote?

 

[alaperse]

Charles I missed the last couple of days and I'm reading bad news. Removing XLR input and LPF won't work for me. Making the LPF/HPF adjustable in the same unit would have been a hit. Ask Nemo Propaganda or Zeus. Sorry I can't be happy with those decisions.

Why do you need LPF? Doesn't your subwoofer has it's own LPF/crossover? What is the model?

Taking out XLR input makes sense if you use the internal DAC (we shouldn't forget that this product is, in it's essential part, a DAC) instead of other source as a DAC. Other sources don't use XLR, just RCA, like a CD player, turntable or deck. Streamer goes to optical input, so still balanced.

 

[nmjona]

You're right, LPF is not necessary, but the convenience of setting the crossover in one single unit is very convenient. I do that with the Emotiva TA2, which has both variable. XLR input is useful for external DACs. Again, unfortunately for me, these changes make me lose interest

 

[zek2024]

XLR input is useful for external DACs.

External DAC as input to the DAC - what for???

 

[nmjona]

Experiment with different sources, the joy of playing around, compare different products and sound changes. Moving from the integrated dac to the Geshelli JNOG3, or SMSL SU9 pro

 

[Toni71]

How is the volume control implemented? With a visible level and a start and stop? The P4 volume is nice.

 

[Peter_P]

Might be a bit late to the party here but I really like your design approach that takes direct feedback from your customers on board. Former Naim user here and I have to say it's great to see the VFM that's coming from the affordable end of the hifi world these days. I used to be quite dismissive of the cheaper stuff but what changed it for me was the Allo products based on the Raspberry Pi. Affordable and they sound awesome. Such a shame that Allo seems to be dead (maybe Fosi could revive the concept! I use Moode on my Allo devices and it's been excellent. No need to reinvent the wheel)

The DAC / Pre-amp idea is great IMO. Absolutely makes sense to have all the switching in one place. This is exactly the kind of product I would go for in a hifi system. A few things I would be looking for:


• DAC in the pre-amp but keep the streamer as a seperate product (nice to have options here, update as technology progresses without having to mess with the major components of the system)

• Maybe a few options of different DAC modules at different performance / price points. Would be nice to be able to upgrade performance without changing product. Start with something cheap / accessible but be able to swap for something premium at a later date. Same goes for power supply options as mentioned below. This could then be Fosi's main pre-amp and the heart of your product line, customisable as the user wishes / can afford.

• Volume knob with fixed ends not an endlessly spinning type (the only volume knob in the entire system. Bit confused as to why the ZD3 / ZA3 combo gives you two. Who needs two!? A bit of a turn off for me)

• 2 x analogue RCA inputs. Could go one of two ways here. 1. no digitisation meaning no mucking with the source signal. 2. gets put into the digital chain allowing DSP ie. a parametric EQ for speaker tuning / room correction. Would be nice to have the option (switchable) but that's probably getting too complex / expensive.

• Minimum 3 digital inputs (USB, coax, optical)

• Bluetooth

• Make the screen simple, clear and modern. No faff. Make sure it can be set to turn off automatically or be in an always on mode.

• Switchable HP filter for setups using smaller speaker and a sub (ideally with a few different frequency settings)

• Different power-supply options at different performance / price points (I guess Naim brainwashed me in this way but Fosi already does this anyway). And why not put them in a proper case so they can be displayed in a rack with the other components rather than just stuffed away messily in the back somewhere!? I have the 48V/5A supply here and it's already fairly well built from what I can tell so I can't imagine it would be a huge leap to put it in a proper case.


But most importantly an emphasis on the SQ performance of the DAC (so that it is intended as the main DAC in the system and the only one you need, not just an add on for convenience). Also great SQ performance from the pre-amp. Would be nice to see a 2 channel Fosi amp much like the mono blocks (no volume control) to pair with the Q8. Keep up the good work

 

[Peter_P]

Should have added that if the idea here is to keep things simple and affordable then I think: good DAC, good Pre-amp, coax in, USB in, optical in, bluetooth, 2 x RCA in with no digitisation, HP filter. Job done.