[ChJL]

one of the benefits of using active pre is to keep output impendence of preamp in check and also the active tube buffer does make sound bigger, bolder and adds to the soundstage. If I get same sound out of tube buffer as without it then I would be disappointed.
I am not talking about the Hattor but active pre in general with tube buffer.

well I can imagine that but it was about the passive, not adding anything Khozmo I'm curious about...

 

[duffer5]

one of the benefits of using active pre is to keep output impendence of preamp in check and also the active tube buffer does make sound bigger, bolder and adds to the soundstage. If I get same sound out of tube buffer as without it then I would be disappointed.
I am not talking about the Hattor but active pre in general with tube buffer@ku@

@kumar402 nailed it. Not much more I can add other than with the passive pre there is no sound added when using volume control which is not always easy to achieve. If you have a resolving system like I do NOT adding anything to the sound pathway allows your system be at its best which is easier said than done thus the benefit of a true passive pre.

 

[ChJL]

@SLC1966 posted this link
https://khozmo.com/product/rca-xlr-without-input-selector/
where it states: Khozmo is a brand that specializes in manufacturing passive preamplifier...

his picture shows that device with Hypsos/OOR.

I was not asking about active pre w tube buffer stage.

I'm interested in how does a passive preamp about which the producer states:

The sound characteristics of a Khozmo preamp can be described as neutral, detailed, and accurate. Khozmo preamps aim to faithfully reproduce the audio signal without adding any coloration or distortion, allowing the listener to experience the music or sound in its truest form.

positively impact Hypsos /OOR?

 

[duffer5]

@SLC1966 posted this link
https://khozmo.com/product/rca-xlr-without-input-selector/
where it states: Khozmo is a brand that specializes in manufacturing passive preamplifier...

his picture shows that device with Hypsos/OOR.

I was not asking about active pre w tube buffer stage.

I'm interested in how does a passive preamp about which the producer states:

The sound characteristics of a Khozmo preamp can be described as neutral, detailed, and accurate. Khozmo preamps aim to faithfully reproduce the audio signal without adding any coloration or distortion, allowing the listener to experience the music or sound in its truest form.

positively impact Hypsos /OOR?

To be honest I think you would be better served reaching out to Arek from Khozmo to get the answer you are looking for. Best of luck in your search.

I have the OOR and with the preamp from Khozmo I can use power amp mode with OOR and I can hear the increased detail, wider soundstage and pureness of the audio as it was meant to be. The preamp is allowing my system to shine all on its own and doesn't add color at all. Your system will only be as good as the signal it can produce as the Khozmo reproduces it like for like without adding anything. Active preamps alter the signal for better or for worse with active gain. If you want your system to reproduce a signal that is pure without an audible change then go passive if you prefer to add color aka noise to some extent go active. I have the best of both, passive with the option of active tube stage.

 

[centuriones]

I wanted to point out the absolute seriousness, professionalism and availability of the Ferrum guys.
They brilliantly solved my problem.
Really great people.

 

[ChJL]

To be honest I think you would be better served reaching out to Arek from Khozmo to get the answer you are looking for. Best of luck in your search.

I have the OOR and with the preamp from Khozmo I can use power amp mode with OOR and I can hear the increased detail, wider soundstage and pureness of the audio as it was meant to be. The preamp is allowing my system to shine all on its own and doesn't add color at all. Your system will only be as good as the signal it can produce as the Khozmo reproduces it like for like without adding anything. Active preamps alter the signal for better or for worse with active gain. If you want your system to reproduce a signal that is pure without an audible change then go passive if you prefer to add color aka noise to some extent go active. I have the best of both, passive with the option of active tube stage.

so you have the Khozmo in between U18/R26 and Oor, right?
I've tried Oor in power amp mode with bad outcome... some on Head Fi suggested the digital volume control of my X26P would be to blame...

 

[duffer5]

so you have the Khozmo in between U18/R26 and Oor, right?
I've tried Oor in power amp mode with bad outcome... some on Head Fi suggested the digital volume control of my X26P would be to blame...

My chain is U18 to R26 via i2s. R26 to Khozmo preamp to active Tube stage. The tube stage can be left off which leaves the passive preamp aka Khozmo at the end of my chain when the tube stage is off. Then obviously to my Oor or my active speakers. I have the volume control on the R26 fixed and only use the volume control on the Khozmo preamp.

 

[Ricco275]

Dear Ferrum lovers fellas, after a few months of utmost sincere love, I’m selling my Ferrum Combo from 2022 in perfect conditions as I’m changing habits (little need for headphones) and 2ch. system. Selling also my almost new Spring 3 KTE.
Feel free to reach out and hope nobody will mind this little advertisement on the thread .

 

[pabbey]

Just wanted to drop a note and say that I just received my Oor recently and after a few hours of burn-in, it sounds really good. I didn’t invest in the option power supply because I wasn’t sure if I was going to like it enough to keep it but I’m pleasantly surprised. It’s warmer than I expected.

Hi @TDinCali, could you tell me what the power supply is that came with the Oor? I’ve got the opportunity to buy a used Oor for a decent price but it comes with a power supply.

 

[Tonza]

Regarding the stock Mean Well PSU that comes with the Oor. I've been using it for a week now and noticed that the front plate and volume pot exhibit some micro vibrations similar to using ungrounded charger on a MacBook or similar laptop with metal frame. It seems to be less than what for example MacBook gives but I was wondering is it the same for others? (Without Hypsos) This is if the Oor is not connected to a grounded source. With a grounded source it goes away. It doesn't affect sound to my ears just curious since I heard that the Oor should have multiple grounds.

Maybe this could be also because of my dac which is ungrounded (and also gives similar vibrations on it's frame) and stacked on top of the Oor. But then again the metal parts don't touch.

 

[plumpudding2]

Regarding the stock Mean Well PSU that comes with the Oor. I've been using it for a week now and noticed that the front plate and volume pot exhibit some micro vibrations similar to using ungrounded charger on a MacBook or similar laptop with metal frame. It seems to be less than what for example MacBook gives but I was wondering is it the same for others? (Without Hypsos) This is if the Oor is not connected to a grounded source. With a grounded source it goes away. It doesn't affect sound to my ears just curious since I heard that the Oor should have multiple grounds.

Maybe this could be also because of my dac which is ungrounded (and also gives similar vibrations on it's frame) and stacked on top of the Oor. But then again the metal parts don't touch.

I had the same "problem" with both my Oor and my Holo May getting the "micro vibrations" as you call them (it's actually a very faint current running through your fingers" I bought an extension cord to plug them into a grounded socket somewhere else in my house and the problem went away. As you said there doesn't seem to be any adverse sound effects but I'm glad I'm not the only one encountering this.

 

[Tonza]

I had the same "problem" with both my Oor and my Holo May getting the "micro vibrations" as you call them (it's actually a very faint current running through your fingers" I bought an extension cord to plug them into a grounded socket somewhere else in my house and the problem went away. As you said there doesn't seem to be any adverse sound effects but I'm glad I'm not the only one encountering this.

Yeah, good to hear that others have encountered this. They are very slight vibrations as you said, my MacBook gives around twice stronger similar effect when charging through ungrounded stock charger. In my case my apartment is quite new (built 2 years ago) and the electrical outlets should be fine and all grounded. For example my monitor on the same outlet grounds the audio stack if connected to laptop which is connected to the dac. (The monitor has charging and output through one usb-c) Could be that the Mean Well PSU leaks some through DC output? I really don't know much about electrical power though. I still should probably test it with other outlets to be sure.

 

[duffer5]

Yeah, good to hear that others have encountered this. They are very slight vibrations as you said, my MacBook gives around twice stronger similar effect when charging through ungrounded stock charger. In my case my apartment is quite new (built 2 years ago) and the electrical outlets should be fine and all grounded. For example my monitor on the same outlet grounds the audio stack if connected to laptop which is connected to the dac. (The monitor has charging and output through one usb-c) Could be that the Mean Well PSU leaks some through DC output? I really don't know much about electrical power though. I still should probably test it with other outlets to be sure.

I would contact HEM the makers of the Ferrum line and let them know what is going on. You may need to have the motherboard replaced to the current version. They will do this at no charge.

 

[Tonza]

I would contact HEM the makers of the Ferrum line and let them know what is going on. You may need to have the motherboard replaced to the current version. They will do this at no charge.

Yeah, I sent them a message and they instructed to try other outlets which I'll do. But the unit should be brand new which I got a week ago. Previous had channel balance issue and they replaced the whole unit so I would expect it to be the latest version. I hope I don't have to send it since it would mean another month plus wait. The last unit I had for 2 days before it went back. The "issue" is very small so I'm not sure would everyone even notice but it's just something that caught my attention when adjusting volume. (I need to be grounded to notice it, sitting on a chair without feet touching ground there's none)

Also reading specs of the power brick (Mean Well GST60), it seems that the negative side of dc output is not connected to ground? No idea if it’s relevant though and could the issue be with leakage current.

 

[duffer5]

Yeah, I sent them a message and they instructed to try other outlets which I'll do. But the unit should be brand new which I got a week ago. Previous had channel balance issue and they replaced the whole unit so I would expect it to be the latest version. I hope I don't have to send it since it would mean another month plus wait. The last unit I had for 2 days before it went back.

I am sorry to read you are going through all these issues. If helpful I know that HEM will support you no matter what. That being said I suspect your logic board is fine if this is a new unit. You can open it up with ease to confirm which logic board you have and is should be 4.2 or greater. I am sure it will be worth it in the end. Keep us in the loop and if there is any group that could provide additional insight it is this group.