MiSTer FPGA Forum

Are there any tips for a compatible type/brand of an external in-line amp out of the spdif/analogue line for the official I/O 6.1 board?

I reckon many of us who use current-day displays (not TVs), without integrated speakers for the MiSTer, would appreciate a hint or two.

Thanks for your answers

For regular analog line out pretty much everything should work fine.
Spdif/Toslink most should work but there are exceptions (have no idé which tough), and it would probably be way easier to list what does not work instead of everything that do.

And spdif is a completely digital signal like toslink (=optical) in fact spdif/toslink do have the exact same signal but one is electrical the other is light based.

I ended up with this one:

https://www.amazon.com/M-Audio-Bass-Tra ... B00X67G77O

Anyone has experience with it?

I would not use a battery powered amp on anything in a "permanent" place/situation for one reasons (two for the mister).
Sure it has usb charge (i assume) but either you charge it with a separate usb chager that has to be switched on/off or run all the time.
And on all the time is NOT recommended since it is the last 10% of the battery charge that wears the battery the most by faaaaaaaaaar.
Leading to the battery loose life fast and when they do not have much life left (which you do not noticed since plugged in all the time) they have a BIG risk of starting to swell and eventually start to leak or explode/start burning (and can be quite the bang).

Or you power it from the mister if so can the power source you use handle the combined draw?
The one that comes with the mister is recommended to not use if you have wifi/bluetooth keyboard/gamepad then add this dac to that!
And how much the dac will draw is probably not much when fully loaded and it probably will work fine, but what if you do not switch on the mister for 2-3weeks+?
Will it draw too much a the start until the batteries is fully charged? What if it lets the batteries go down 10-20% then starts charge them in the middle of playing and it draw too much?

if you intend to use active speakers, with built-in volume control, just use line out from io board, max out the volume on mister and control it with the volume control of your active speakers. passive speakers need speaker amp, so you will control it[probably] at the amp. with headphones, get something like geshelli enog and archel, or a dac/amp unit, you can get something cheaper, something priceier, sky is the limit. there are a lot of great dacs with toslink input and then connect whatever headphone amp fits your needs.

Thanks everyone for your input!

I've already ordered the device linked above; it's the only decent looking one I've found available locally for a reasonable price.

I'm intending to use passive headphones [I already do plug them directly in the I/O board] rated @ ~100Ω. Some cores sound ok-ish, some don't, that's why I went around searching for an external amp in the first place.

Thank you again!

I'm very happy with a FX-Audio DAC-X6 and a Divlpoetry TUBE-6J1 preamplifier. It sounds great and the price is affordable.

Yeah since I posted this topic, I got an external DAC and I'm looking into buying a small and cheap vacuum tube amp such as the above.

Thanks paco!

At my computer I use these, great gift from my wife:

https://www.amazon.com/Vanatoo-Transpar ... B01N33WUJ9

They take optical in as a source, and sound amazing and don't take up a lot of desk space. Not budget friendly but it's audiophile gear so, hey, what're ya gonna do.

For a DAC to use with my CRT or with headphones (without using the 3.5mm connector which is really noisey) I send optical to this --> https://www.amazon.com/Converter-Blueto ... 082NTDX9Q/ - and it works well for how cheap it is.

The tube preamp suggestion, personally, is a little off. You don't need a preamp since the MiSTer is already outputting a signal that doesn't need that kind of modification, and if you have a DAC it already has preamps in it to push out the analog signal. If you are sending the audio to a pair of powerd speakers, they have amps as well. If you want to modify the bass and treble in-line though, I can see why that preamp comes in handy however. Kinda cute little tube preamp, looks cool!

Cool thing about the preamp is that you can correct the volume difference between cores easily, and due to 2x gain you don't have to turn the volume too high in the TV. It also gives a warmer sound, and allows you to boost bass or treble.

About the DAC-X6, I get better sound from the RCA output than from its built-in headphones amplifier. This way you can't correct volume level if you don't have the preamp.

the point of preamp in a mister setup is exactly for something like active speakers, where you set their amp and never touch them again. thats why preamps exist, to make volume control more comfortable and practical. however, if you want a preamp for mister and dont have a dac yet, look for a dac with volume attenuator[probably with volume control], something like rme adi-2 or smsl-sh9 or many others
EDIT: or if you want even more fpga in your life, go for aune x8, one of the few[if not only] affordable fpga dacs out there[of course, you can always break the bank with something like ps audio directstream dac]

FX-Audio DAC-X6 and Divltpoetry TUBE-6J1 cost around 30€ each on Aliexpress. Unbeatable quality for the price.

There are also 6J1 preamp kits from ~7€, but they require a 12V AC power supply.

pacoarcade wrote: ↑Sun Jan 17, 2021 11:41 am FX-Audio DAC-X6 and Divltpoetry TUBE-6J1 cost around 30€ each on Aliexpress. Unbeatable quality for the price.

There are also 6J1 preamp kits from ~7€, but they require a 12V AC power supply.

"Unbeatable quality for the price" is a strange choice of words in this case. avoid really cheap audio gear, its often barely better than whatever integrated part you are trying to replace. do your homework, look up reputable DACs and other gear, look for how they perform, what they offer. schiit, gesheli, smsl, topping. if you want cheap but good[still verify if they are actually good], go with one of these.
https://www.audiosciencereview.com/foru ... e10k.2097/

On a related note, Porkchop Express of misteraddons.com fame, dived into exploring a software solution.

Crystal wrote: ↑Sun Jan 17, 2021 3:31 pm "Unbeatable quality for the price" is a strange choice of words in this case. avoid really cheap audio gear, its often barely better than whatever integrated part you are trying to replace. do your homework, look up reputable DACs and other gear, look for how they perform, what they offer. schiit, gesheli, smsl, topping. if you want cheap but good[still verify if they are actually good], go with one of these.
https://www.audiosciencereview.com/foru ... e10k.2097/

Thank you for the link, it's nice to see actual measurements instead of just audiophile sensations. Anyway, I wonder if this experiment has been done taking the audio from the headphone output that includes amplification - in my tests I don't like how it sounds this way. However, using the RCA output the unit acts as a pure DAC without the headphone amplification (so the volume knob will not do any effect), and I can appreciate an improvement compared to the output of the HDMI to VGA converter.

Of course there are better DACs out there, but this one only costs ~30€, and I'm happy with it. Good bang for the buck in my honest opinion.

Today I've replaced the 6K4 tubes from the preamp with GE 5654W tubes and the sound upgrade is notable. I like this preamp so much that I bought another one for my computer, it clearly improves the sound I get from a pair of Sony SRS-A205 PC amplified speakers.

If I had to choose only one of these items for my MiSTer setup, I'd go for the preamp.