Preout setting when connecting external headphone amplifier

Function IN/OUT Settings
#1

Hello fellow Hifi Rose users. @ROSEHAN @ROSELOA

I have the age old question regarding the preamp settings when connecting a external headphone amp.

I plan on using two headphone amps with my HifiRose 150b and setting the 150b to fixed volume while using the variable volume of the headphone amp(s). Keeping in mind one amp will be connected to the 150b at a time not both.

Headphone amp 1:

Input sensitivity (XLR balanced in / out)

9.3Vrms @G=L

3.0Vrms @G=H

Headphone amp 2: (XLR balanced in / out)

Input sensitivity

18 Vrms @G=L

What should I be setting the 150B preamp to based on the above input sensitivity of the above two amps keeping in mind I can change the preamp output on the Hifi Rose 150b per external amp as needed.

I appreciate the sage advice in advance.

#2

Hello @ROSELOA and @ROSEHAN , I am just following up on the above for your guidance. Thank you.

#3

Hello,

Seems like you hope to fix the output of the RS150B, the “Pre-out level settings”.
In fact, “Pre-out Level settings” is same as the volume, so it doesn’t really matter which value you set.
RS150B can output up to 6.5Vrms for balanced output, which is still not enough for your headphone amplifier. I would fix on 6.5Vrms for RS150B and change volume on headphone amplifier.

In general, rather than amplifying a small value a lot by the amplifier, it is advantageous for sound quality to amplify a large value from the source streamer a little in the amplifier.

Just in case, never never change volume with your headphone on your ears, maybe you can feel the volume is to loud.

#4

This is very helpful. Do you suggest I use an external pre-amp between the 150b and my headphone amp or do you think the output of the 150b’s preamp is more than sufficient. Thank you.

@ROSELOA @ROSEHAN

#5

@ROSELOA @ROSEHAN

I need your help once again. I am using the Ferrum OOR headphone amp and either the makers of the amp are confused or I am confused.

I am trying to set the 150b to the highest output that won’t overdrive my HifiMan Susvara’s into the Ferrum headphone amp. The below are the numbers they are giving me. Can you decipher what output I should set the preout to with the below numbers from Ferrum?? Are the output of the preout for the 150b with a max of 6500mV (balanced) average or peak to peak.

This is the input sensitivity of the Ferrum headphone amplifier:
“4Vrms is 5.64V average and 11.28V peak to peak”

#6

@duffer5

I apologize for the late reply.

We don’t know about the Ferrum headphone amp, and we don’t have it, so we can’t give you an exact answer, but the input sensitivity of the Ferrum headphone amplifier is 4Vrms is 5.64V average and 11.28V peak to peak, you can use the value of Pre-out level setting to about 4000mV.
If there is no particular problem such as clipping, you may select and use a higher option.

Thank you

#7

Hello Hifi Rose,

I really do appreciate the reply but 26 days to answer my prior question is just not acceptable no matter the “good” intentions of Hifi Rose. Support after the sale is the key to your success. Fix it quickly or mass adoption will be short lived. Just a friendly suggestion.

#8

@duffer5

We will do our best to become a Hi-Fi Rose that accepts your suggestion and develops.

Thank you

#9

I am looking at your answer once again and I am confused regarding your response. Are the Rose Values V average ( I assume that is the case as it is most common) so if that is the case the results would be for 4V rms:

P (dBm) : 25
P (mW): 316.228
Vrms (V): 3.976 (closest value to 4V rms as quoted by Ferrum manufacture)
Vp (V): 5.623
Vpp (V): 11.247

Assuming that the Rose values are V average should I just start at 5000 Mv balanced and increase from there.

With your answer you are assuming that 4 Vrms (input sensitivity from Ferrum) is the same as 4000mV which just is not that case.

Can you please clarify.

#10

@duffer5

I’m sorry for the late reply.
I don’t know much about Ferrum manufacture.
As a result of checking with the person in charge of the software, it is not possible to say that it is exactly the same as 4Vrms and 4000mV, but there seems to be no problem in setting and using it like this.

Thank you

#11

This really is not a software engineering issue it is an electrical engineering issue. The simple question is are the output levels for the XLR preout’s V average if so then the conversion from mV to Vrms is easier to understand. A suggested change is to include the value of Vrms in the output settings of the Preout XLR and RCA as many headphone amps use Vrms as their “input sensitivity,” value not mV? So can you please provide this response and my prior response to your electrical engineering team / person and they should be able to answer this easily. I would appreciate it. @ROSELOA @ROSEHAN

#12

@duffer5

Hi-Fi Rose does not have an electrical engineering team, so I asked the hardware team a questions and received answers.
For Vrms (V): 3.976, input sensitivity can be set to 3000mV.
They also said that clipping may occur if set to a value higher than 4000mV.

Thank you, hope this answer helps

#13

Once again Vrms does not equal V. You have now given me 4 different answers and I have provided the same info each time.

#14

@duffer5

I apologize for giving different answers each time.

The threshold with the highest knowledge in this field, Vrms and V are different, but assuming that the input sensitivity of the amp being used is 3.976 Vrms, it is best to set it to 3000mV and use it.

Thank you

#15

Is the output via preout “average,” or “peak” or something else. This is for the Hifi rose 150b output. More specifically you label the output in mV. Is the mV output “average,” or “peak.” This makes a big difference when comparing to vRMS input sensitivity on an amplifier.

Thank you.