MiniDSP Flex HTx

[Nick Laslett]

I have been using the VAX04101A from day one with my flex HT (as my source - internet TV box doing bitstream decoding - is only ARC).
I never got any issues (no pops nor clicks) with it.
Here is the env I am using.

Thank you. Great setup, really appreciate the schematic. Sorry to hear about the aesthetic challenges with the surrounds.

I didn’t consider that the Flex HTx would enable dual Subs. Is it something that can be configured in the software? Or does it require additional hardware?

*Edit. A quick google turned up this guide on MiniDSP for using MSO software for dual subwoofer optimisation. I might be over thinking how difficult it is to use the Flex HTx to incorporate a dual sub setup.

2.2 Sub integration + MSO

miniDSP is a leading manufacturer of Digital Audio Signal Processors for the HomeTheater, Hifi, headphone and Automotive market. Join our large community of Audiophiles, Engineers and DIYers using our innovative products.

www.minidsp.com

 

[vicenzo_del_paris]

Thank you. Great setup, really appreciate the schematic. Sorry to hear about the aesthetic challenges with the surrounds.

I didn’t consider that the Flex HTx would enable dual Subs. Is it something that can be configured in the software? Or does it require additional hardware?

*Edit. A quick google turned up this guide on MiniDSP for using MSO software for dual subwoofer optimisation. I might be over thinking how difficult it is to use the Flex HTx to incorporate a dual sub setup.

2.2 Sub integration + MSO

miniDSP is a leading manufacturer of Digital Audio Signal Processors for the HomeTheater, Hifi, headphone and Automotive market. Join our large community of Audiophiles, Engineers and DIYers using our innovative products.

www.minidsp.com

Flex HT as 8 inputs and 8 outputs.
Thus you can do water you want in terms or routing and DRC
My subs are colocated with my mains.
Left sub beside left main and right sub beside right sub.
Not an initial choices but imposed by both the way the room+furniture is setup and my wife.
In stereo mode, I route left channel to left main speaker and left sub and same for right channel.
In multichannel mode, I route LFE to both subs.
Prior doing any RC (I use Dirac), I made many tries to find out the right crossover frequency (regarding the sub and mains).
I ended up with a 70hz XO, with a 48db BW filter for both subs and speakers (with inverted phase for subs due to my Focal mains). This resulted in no dips/cancellation) in the bass and sub bass regions. Except a tiny very narrow dip and some very limited ringing which is linked to the room configuration.a'd MLP location.
And as subs are colocated to speakers, there is no noticeable issues with delays.
Then I rely on Dirac to generate the filters (both in stereo and multichannel modes).
In stereo mode, Dirac doesn't see the subs and considers them as part of the mains.
Results is the very linear response from 20 to 100hz with only a +/- 1 db deviation.

 

[danstahl]

I have been using the VAX04101A from day one with my flex HT (as my source - internet TV box doing bitstream decoding - is only ARC).
I never got any issues (no pops nor clicks) with it.
Here is the env I am using.

Only ARC? Two channel?

 

[vicenzo_del_paris]

Only ARC? Two channel?

I use the flex HT for :
- stereo music (toslink input)
- TV/Movies (HDMI input)

The Flex HT, as mentioned many times, supports only LPCM (up to 7.1) through eARC.
As my AV source (internet provider TV box) is doing bitstream (including Atmos) decoding to LPCM 7.1 but not over eARC, I needed the feintech device between the source/TV and the Flex HT to make them appears as eARC.
I have 2 presets on the Flex for handling AV streams:
- one for 5.1 content (simple routing) where each input is mapped to one output.
- one for DD 2.0 content where there is more config (king of very basic upmixing) to route L+R to center and subs with basic filters.

 

[danstahl]

I use the flex HT for :
- stereo music (toslink input)
- TV/Movies (HDMI input)

The Flex HT, as mentioned many times, supports only LPCM (up to 7.1) through eARC.
As my AV source (internet provider TV box) is doing bitstream (including Atmos) decoding to LPCM 7.1 but not over eARC, I needed the feintech device between the source/TV and the Flex HT to make them appears as eARC.
I have 2 presets on the Flex for handling AV streams:
- one for 5.1 content (simple routing) where each input is mapped to one output.
- one for DD 2.0 content where there is more config (king of very basic upmixing) to route L+R to center and subs with basic filters.

Gotcha.

I'm trying to isolate where the clicks may be coming from, and why you don't experience it .

Some reasons that I can think of:

• Your TV box doesn't introduce "clicks" on changing formats...or perhaps never changes formats, unlike my Kodi box. This seems the most likely reason. A quick google search shows that the AppleTV also has this issue over eARC, so it may just be the nature of eARC+changing formats.
• Your Feintech device is better at eArc than my Ezcoo (I would consider this to be most likely except HDFury, which I consider a more "high end" device, apparently also has the same issue).
• Faulty HDMI chord
• Faulty MiniDSP

 

[vicenzo_del_paris]

Gotcha.

I'm trying to isolate where the clicks may be coming from, and why you don't experience it .

Some reasons that I can think of:

• Your TV box doesn't introduce "clicks" on changing formats...or perhaps never changes formats, unlike my Kodi box. This seems the most likely reason. A quick google search shows that the AppleTV also has this issue over eARC, so it may just be the nature of eARC+changing formats.
• Your Feintech device is better at eArc than my Ezcoo (I would consider this to be most likely except HDFury, which I consider a more "high end" device, apparently also has the same issue).
• Faulty HDMI chord
• Faulty MiniDSP

On the feintech device, you can set the edid to auto, 2.0, 5.1 or 7.1.

I have set it to 5.1 or 7.1, not auto.
My source doing the decoding, it always send LPCM, maybe with a fixed format.

 

[danstahl]

On the feintech device, you can set the edid to auto, 2.0, 5.1 or 7.1.

I have set it to 5.1 or 7.1, not auto.
My source doing the decoding, it always send LPCM, maybe with a fixed format.

Ah interesting! Mine only supports 4k 7.1, 4k 5.1, 4k 2.1, and "copy" (uses the EDID from "output1"). I don't have a 4K projector so I stick with "copy". The MiniDSP "sees" 2.0 and 7.1 when Kodi switches between music and movies.

 

[vicenzo_del_paris]

Ah interesting! Mine only supports 4k 7.1, 4k 5.1, 4k 2.1, and "copy" (uses the EDID from "output1"). I don't have a 4K projector so I stick with "copy". The MiniDSP "sees" 2.0 and 7.1 when Kodi switches between music and movies.

I don't use HDMI for music so I can't tell.
I only use HDMI for AV streams.
I have just checked:
- With TV channels (DD 2.0) Flex HT reports 2 channels
- With netflix and prime video (5.1), Flex HT reports 6 channels.

Never got any glitches nor pops.
Transition between formats and streams are completely smooth and silent.

 

[peng]

I am new to the Flex HT/HTx and have a question on the input volume offset, according to minidsp, there is adjustment to the volume offset that could reduce or void ISPs. The SHD and Flex has recently been updated to have this adjustment, but the newer models HT and HTx are supposed to have this feature.

I read the manual and search for information on this and found nothing that could help in locating the adjustment settings. Anyone know how and where this adjustment setting is?

One moment, please...

Our solution to ISPs in the Flex is to allow the user to reduce the level of the digital signal before it enters the ASRC. This is accomplished by setting the input volume offset of specific inputs to a negative value. A value of -2 to -4 dB is all that is needed:

 

[Mort]

but the newer models HT and HTx are supposed to have this feature.

Where do you see this?
My Flex has this feature but my Flex HT does not.

 

[peng]

Where do you see this?
My Flex has this feature but my Flex HT does not.

Will send you link later.

 

[peng]

Where do you see this?
My Flex has this feature but my Flex HT does not.

Found it:

Device Console ChangeLog

The following software changeLog summarizes the changes made to the miniDSP Device Console (DC). As a reminder, please note that XMOS and DSP firmware are packaged together inside the miniDSP DC and that you may be requested to upgrade your firmware in order to use the latest version of miniDC...

www.minidsp.com

Major SHARC DSP firmware update:
- Volume offset at input before ASRC to solve the inter-sample issue on digital source "2x4HD, DDRC24, Flex, Flex-DL, Flex8, Flex8-DL, SHD series" / Flex-HT&HTx already implemented this update in earlier
builds.
- Support Vol-Offset "Flex, Flex-DL, Flex8, Flex8-DL, SHD series" to get various sources to match level change

You can see that the Flex, SHD etc., got the update in version 1.1.18 (note that we are at 1.1.20 now as of today), on Nov 25, 2024, whereas the HT & HTx had it implemented in earlier builds.

Note that it says "support vol-offset "Flex,.....SHD series" but no mentioning of the HT & HTx. Anyway, I opened a ticket on minidsp support and they responded briefly, confirming the HT/HTx had the update in earlier version and the Flex, SHD just got caught up later, but by the time I asked them about the adjustment settings, there has been no response, most likely they went on a two weeks holidays already, so may be some time in the New Year. The rep even suggested that they confirmed there was sonic improvements with the update.

I have since tried listening to some of Adele's, that previously I could hear distortions when she ramped up, now playing through the Flex HT, I no longer hear such distortions, or at least much less obvious. So may be whatever they did, by having input volume control before the ASRC, they managed to reduce ISP related distortions to much lower level if and when such inter sample peaks occurred, may be by a fix amount or something, but without providing adjustable setting via the offset that the Flex/SHD has. But I am just guessing. Will keep you posted if I get a respond from minidsp.

 

[Mort]

Good catch. I actually read that and wondered what it meant since afaik, it's not on the HT or HTx. I can't speak to the sonic qualities but it would be convenient to equalize sources.

 

[rirelien]

Hello @rirelien, does your FeinTech VAX04101A have issues with pops and clicks, like this user has with HDFury options?

I do get an occasional pop, though much less than earlier this year. In my case I strongly suspect the AppleTV, where it mostly happens when switching to/from stereo/multichannel.

Firmware updates on the MiniDSP and OS updates on the ATV have improved it.

Given this apparently happens with both the HDFury and Feintech devices, I’m inclined to think the problem is elsewhere.

 

[rirelien]

On the feintech device, you can set the edid to auto, 2.0, 5.1 or 7.1.

I have set it to 5.1 or 7.1, not auto.
My source doing the decoding, it always send LPCM, maybe with a fixed format.

As another user who sometimes has mild clicks: I use 5.1, not auto setting.

 

[rirelien]

I have been using the VAX04101A from day one with my flex HT (as my source - internet TV box doing bitstream decoding - is only ARC).
I never got any issues (no pops nor clicks) with it.
Here is the env I am using.

Firstly, I think I bought the FeinTech based on a post from you, and I’ve been very happy with it. Thanks!

Secondly, I’m curious how you get more than 2.0 LPCM if the set top box only supports ARC, as I believed that standard does not support sufficient bandwidth for more than 2 channels of uncompressed PCM?

Lastly, I suspect the ATV in the mix, in my case, is at least partly responsible for the occasional click and pop.

 

[vicenzo_del_paris]

Secondly, I’m curious how you get more than 2.0 LPCM if the set top box only supports ARC, as I believed that standard does not support sufficient bandwidth for more than 2 channels of uncompressed PCM?

You're right about ARC .
But I presume the feintech gets the hdmi data from my source (lpcm 5.1, no ARC involved), acts as an earc device and sends the audio stream to the flex via earc.

 

[danstahl]

Ah interesting! Mine only supports 4k 7.1, 4k 5.1, 4k 2.1, and "copy" (uses the EDID from "output1"). I don't have a 4K projector so I stick with "copy". The MiniDSP "sees" 2.0 and 7.1 when Kodi switches between music and movies.

I dug a little deeper, seems like a lot of "clicks" were blamed on CEC. I turned off CEC in my Kodi box...and the clicks seem to have gone away. I stress tested with music and movies and so far no clicks or pops.

 

[peng]

I have since tried listening to some of Adele's, that previously I could hear distortions when she ramped up, now playing through the Flex HT, I no longer hear such distortions, or at least much less obvious. So may be whatever they did, by having input volume control before the ASRC, they managed to reduce ISP related distortions to much lower level if and when such inter sample peaks occurred, may be by a fix amount or something, but without providing adjustable setting via the offset that the Flex/SHD has. But I am just guessing. Will keep you posted if I get a respond from minidsp.

About the Inter-sample peaks related distortions, I have now received a response from minidsp. They basically confirmed that the Flex HT and HTx did have the "fix" implemented in early updates, by having volume control before the ASRC, as they told me before, the Flex models recent updates are just catching up. They acknowledged that the HT and HTx's Device Console did not have the input volume-offset adjustment settings like the Flex did, but also told me:

"We have plans to launch the HT/HTx with an input level offset in the future, although a timeline has not yet been established."

So, until we get the next update, to avoid clipping the ASRC, my understanding is as follows based on their response:

"Flex HT/HTx also has ISP prevention by having the master volume control BEFORE the ASRC. i.e. put -3dB and you will be able to input +3dFS track."

That to me, is not an issue at all because I never set my mV that high anyway, even using my relative low gain buckeyeamp NC502MP.

 

[Blantto]

Have been watching this thread interested in the HTx. Have had it for a couple days now. Have it paired with a Buckeye 3 channel Purifi 2nd gen, Q Acoustics front 3, SVS sb1000 (3.1 only) and a Win 11 PC that I use a source. In the PC I have a Sound Blaster AE9 with Sparkos 3602s which I think sounds amazing on 2 channel. I was worried the sound would be diminished by adding this in the chain. Happy to report that to my ears it doesn't, transparent. As measured, what goes in comes out the same. Thank you to the testers and moderators for making this resource available. This heavily influenced my decision to get this processor-- and the Buckeye. Couldn't be happier. Thanks