What a Balance Preamplifier Should Be Like?

[antcollinet]

I am a L/R type, and not into centre/center or multi-channels.
Thank you for the correction.

If that is truly a 'summed' output; can it be used for a sub-out, absent an LPF downstream?

I don't know of any powered subs that don't include their own LPF.

 

[xanalog]

I don't know of any powered subs that don't include their own LPF.

Does this make the ZP3's built-in HPF switch unnecessary/redundant, since that 'sub' output appears to be a mono out [summed and full range to 20kHz]?
Would you have any example of a use case?

 

[obsessive9119]

Does this make the ZP3's built-in HPF switch unnecessary/redundant, since that 'sub' output appears to be a mono out [summed and full range to 20kHz]?

No, because the HPF is for the mains.

 

[antcollinet]

Would you have any example of a use case?

Full range summed output to sub. Let the sub apply it's own low pass filter.

High pass filter applied to the main LR speakers, so they don't attempt to produce the low frequencies the sub is dealing with.

 

[jj7600]

Is the volume pot not motorized like the P4’s? And does it have a similar relay ladder for the volume control? I’ve been very interested in this one, assuming/hoping it would essentially be a balanced P4.

 

[avdoc]

Is the volume pot not motorized like the P4’s? And does it have a similar relay ladder for the volume control? I’ve been very interested in this one, assuming/hoping it would essentially be a balanced P4.

The volume pot is NOT motorized. It would be much, much more useful if it was. I don't know what type of volume control it has.

 

[Karlaka]

Good afternoon, gentlemen.
Based on Avdoc's assessments, we can now draw some conclusions.
I'd really love to have a test unit, but in the absence of that, we can look at the experience of this user who kindly shared his experience with us.
The difference in output level between the RCA and XLR outputs could really be a problem. In fact, it should be higher on the balanced ones since the voltage is higher, but Avdoc indicates otherwise. This is very unusual.
Moving on, the HPF that several of us had been requesting has become a reality (I believe I was the first user to propose the development of a preamplifier with these features in the "Idea Harvest" section).
The attenuations Avdoc mentions at both 80Hz and 120Hz make sense, as the cutoff isn't abrupt, but rather gradual. However, based on this, I would think it appropriate to add another position at approximately 160Hz, or change the existing ones to slightly higher values. For example, 100Hz and 160Hz, to cover the widest range of frequencies that most subwoofers on the market can reproduce.
Finally, what I consider a notable mistake is equipping the unit with an infinitely variable (or infinite rotation) volume control, with all the risks that this entails. One of the P4's most attractive features is its motorized volume control with minimum and maximum levels. I believe this should at least be replicated in the ZP3 with the highest-quality potentiometer possible, considering its intention to be an analog preamplifier with superior features. Also, the fact that the input selection is on the same volume knob does not seem at all attractive to me; they could have put dedicated buttons or a selector knob.
I trust the Fosi team can iron out these minor details before releasing the final model, and I'm extremely pleased that they've taken on the challenge of producing a preamplifier that I consider a fundamental link in the audio chain.
Best regards!

 

[avdoc]

Good afternoon, gentlemen.
Based on Avdoc's assessments, we can now draw some conclusions.
I'd really love to have a test unit, but in the absence of that, we can look at the experience of this user who kindly shared his experience with us.
The difference in output level between the RCA and XLR outputs could really be a problem. In fact, it should be higher on the balanced ones since the voltage is higher, but Avdoc indicates otherwise. This is very unusual.
Moving on, the HPF that several of us had been requesting has become a reality (I believe I was the first user to propose the development of a preamplifier with these features in the "Idea Harvest" section).
The attenuations Avdoc mentions at both 80Hz and 120Hz make sense, as the cutoff isn't abrupt, but rather gradual. However, based on this, I would think it appropriate to add another position at approximately 160Hz, or change the existing ones to slightly higher values. For example, 100Hz and 160Hz, to cover the widest range of frequencies that most subwoofers on the market can reproduce.
Finally, what I consider a notable mistake is equipping the unit with an infinitely variable volume control, with all the risks that this entails. One of the P4's most attractive features is its motorized volume control with minimum and maximum levels. I believe this should at least be replicated in the ZP3 with the highest-quality potentiometer possible, considering its intention to be an analog preamplifier with superior features. Also, the fact that the input selection is on the same volume knob does not seem at all attractive to me; they could have put dedicated buttons or a selector knob.
I trust the Fosi team can iron out these minor details before releasing the final model, and I'm extremely pleased that they've taken on the challenge of producing a preamplifier that I consider a fundamental link in the audio chain.
Best regards!

To be clear, the input selection is a separate button (it doubles as the power button) distinct from the volume knob.

 

[Karlaka]

Hello, Avdoc.
Thanks for the clarification. Apologies, it was my misinterpretation; it's perfectly clear in your description.

 

[Karlaka]

Is 160Hz enough? Do you need 180Hz?

Yes, it could be.
Considering that most of the active subwoofers I know have a LPF ranging from 40Hz to 200Hz, I think two positions sufficiently separated between 80Hz and 200Hz would be fine, don't you think? That's why I suggested 100Hz and 160Hz, but it could easily be 100Hz and 180Hz.

 

[TonyJZX]

the vol knob 'free spin' is an issue that should have been picked up in like the 1st prototype stage

this just isnt good or safe or common sense design

they could have included like a row of square leds that lights up to show vol. level that could have nullified this

the mono summed pre-out that operates as a subwoofer out is something i can overlook but the vol. knob sounds like something that would forever grate you

this plus the fact they cant maintain vol. consistency between inputs makes this very challenging to use regardless of paper performance

 

[Karlaka]

the vol knob 'free spin' is an issue that should have been picked up in like the 1st prototype stage

this just isnt good or safe or common sense design

they could have included like a row of square leds that lights up to show vol. level that could have nullified this

the mono summed pre-out that operates as a subwoofer out is something i can overlook but the vol. knob sounds like something that would forever grate you

this plus the fact they cant maintain vol. consistency between inputs makes this very challenging to use regardless of paper performance

Hi, Tony.
Except for the row of LEDs, i agree with all your observations.
For a product like this, I think a motorized knob with maximum and minimum stops, limited rotation, and good feel is essential (a huge mistake on the WiiM Ultra).
After all, in a preamplifier, I think the volume control is one of the most important details.

 

[xanalog]

Co-Create - Multichanel Preamp

Co- Create Multichanel preamplifier Hi everyone! I have been thinking about a multi-channel preamplifier for a long time, I think it would be very necessary. Unfortunately, I don't know the parameters of the lc40 that is being made now, I just read that it is being made.. maybe I am knocking...

community.fosiaudio.com

 

[Wmacky]

Is there even time for changes or has production started? I've never heard of a volume without stops unless digital? I may have to for go Balanced connections and go P4, but then no trigger either! I really love the ZP3 look, I hope something can be done? And those uneven levels too!

 

[nongnet]

ZP3 is designed with round edges front and back.
All ZA3, ZD3, P4, V3 mono and V3 have round edges left and right.
No consistency in design like Japanese or Korean.

 

[avdoc]

I emailed my initial review to Fosi. My impression is that I was sent a very early prototype that may not be representative of the finished product. They have asked me to take down my review and their engineers are evaluating the deficiencies I pointed out. Hopefully, they will address some of the flaws prior to launch. I have reported my original review post and asked that it be taken down. Fingers crossed as I was very impressed with the sound.

 

[Karlaka]

I emailed my initial review to Fosi. My impression is that I was sent a very early prototype that may not be representative of the finished product. They have asked me to take down my review and their engineers are evaluating the deficiencies I pointed out. Hopefully, they will address some of the flaws prior to launch. I have reported my original review post and asked that it be taken down. Fingers crossed as I was very impressed with the sound.

Excellent news, AvDoc!
I think we all agreed on the details you pointed out that needed to be corrected, such as the infinitely rotating volume control, the level discrepancy between the outputs, and, personally, the scale chosen for the HPF levels.
I really have very high expectations for this product. Fosi has been doing a great job while maintaining budget prices.
Well done to them!

 

[xanalog]

such as the infinitely rotating volume control,

When the FOSI ZA3 was introduced, I had noticed that the orange VC knob had a dimple but you could not see it from a few inches away.
I dabbed a bit of white nail-polish on the dimple for visibility and I had suggested such a knob marking to them.

 

[Karlaka]

Hi, Xanalog.
That's a good point, but on an infinitely rotating knob, it wouldn't be much help. The ZP3 really should have a motorized knob, with maximum and minimum values, just like the P4.
Or at least, that's my humble opinion.

 

[xanalog]

That's a good point, but on an infinitely rotating knob, it wouldn't be much help.

I had added that bit, in case they decide to undo infinite-rotation, while doing the visible marking. [evil, I know. ]

...just like the P4.

Have you gotten a P4?
I think the shipments have been delayed.