Hello,
I am on the way to design an amplifier for input signals coming from RCA and XLR connectors.
I am wondering what is the sensitivity to target for those two inputs as my amplifier may provide 100W max. I am targeting something like x30 gain. Is it correct?
I couldn't find any reference document for the maximum level acceptable in both case.
So if you are aware of :
- maximum level in both case
- recommended sensitivity
- maximum common mode voltage for XLR
Any comment appreciated!
Best regards
Laurent
I am on the way to design an amplifier for input signals coming from RCA and XLR connectors.
I am wondering what is the sensitivity to target for those two inputs as my amplifier may provide 100W max. I am targeting something like x30 gain. Is it correct?
I couldn't find any reference document for the maximum level acceptable in both case.
So if you are aware of :
- maximum level in both case
- recommended sensitivity
- maximum common mode voltage for XLR
Any comment appreciated!
Best regards
Laurent
domestic use or commercial use?
For domestic use, we usually see sensitivities between 100mVac to 1Vac for full power.
For commercial use, we usually see +4dBu to +10dBu.
For domestic use, we usually see sensitivities between 100mVac to 1Vac for full power.
For commercial use, we usually see +4dBu to +10dBu.
Maybe I can be more precise on my request.
As in put stage will be connected to RCA or XLR, I need to know if I must apply various attenuation according to the input selected.
I am ok to have 1V for full power using RCA.
Does it make sense to have 1V for fullpower using XLR (1V is differential in this case)?
As in put stage will be connected to RCA or XLR, I need to know if I must apply various attenuation according to the input selected.
I am ok to have 1V for full power using RCA.
Does it make sense to have 1V for fullpower using XLR (1V is differential in this case)?
Yes, if it was for me alone, I would just do like that. But the aim is probably to make some of them and I would like to be sure it is compatible with any symetric/asymetric input.
When you say 1V, is it for RCA or XLR?
When you say 1V, is it for RCA or XLR?
You want to make some of them? So you want to manufacture as a commercial design, yet you do not understand sensitivity?
If you are going professional / commercial you need to pay for design assistance. Perhaps the guys on this forum that help you can take a share of your profit?
Or is this forum a free help-line for incompetent marketing men?
If you are going professional / commercial you need to pay for design assistance. Perhaps the guys on this forum that help you can take a share of your profit?
Or is this forum a free help-line for incompetent marketing men?
...?
Couldn't guess it could be seen like that...
It is not for business, I already have a job it is on RF not Audio...
I know what is sensitivity, the level for a given power, max power in my case.
I know electronic (I am IC designer), but I don't know the standards used for audio. And I may change my sources so I need to align to a standard.
The question is on the max level to be encountered on XLR connectors, I have none of those items at home.
Why do I ask here? Because it is DIY Audio a good place to ask questions on Audio. I have asked on a french site, but the response was unclear, less technical guys.
When I said I would like to study an amplifier for my own needs, I proposed to share results (for free!) and I have been asked if it could support symetric input (some of my friends have Cello Preamp and they adjust the sensitivity with strap according to the input). So I am investigating it. But when I go to Spice, I wonder what is the maximum input voltage (should I withstand 2V peak voltage for my input differential stage or not?)
I already asked some questions about triggers, differential input, valves, power supplies and got some answers. I read books and have some others. This last question was not offending for me.
Do you mean I have to pay to have a technical information on a public forum?
Couldn't guess it could be seen like that...
It is not for business, I already have a job it is on RF not Audio...
I know what is sensitivity, the level for a given power, max power in my case.
I know electronic (I am IC designer), but I don't know the standards used for audio. And I may change my sources so I need to align to a standard.
The question is on the max level to be encountered on XLR connectors, I have none of those items at home.
Why do I ask here? Because it is DIY Audio a good place to ask questions on Audio. I have asked on a french site, but the response was unclear, less technical guys.
When I said I would like to study an amplifier for my own needs, I proposed to share results (for free!) and I have been asked if it could support symetric input (some of my friends have Cello Preamp and they adjust the sensitivity with strap according to the input). So I am investigating it. But when I go to Spice, I wonder what is the maximum input voltage (should I withstand 2V peak voltage for my input differential stage or not?)
I already asked some questions about triggers, differential input, valves, power supplies and got some answers. I read books and have some others. This last question was not offending for me.
Do you mean I have to pay to have a technical information on a public forum?
Last edited:
Take a 225 to 300mV rms sensitivity in RCA plugs.
For XLR, standard is about 775mV rms, with an overload
margin of +20db, that is 7.75V rms..
For XLR, standard is about 775mV rms, with an overload
margin of +20db, that is 7.75V rms..
Thank you wahab for your inputs.
7.75V is high. Some attenuation may be necessary for that input.
Will go on investigate that.
7.75V is high. Some attenuation may be necessary for that input.
Will go on investigate that.
The sensitivity is 775mV, but the circuit that fed the amp
must be capable of 7.75V output, which is the case of op amps
supplied with +-15V.
This apply only to the preamp or the mixing console that is in
the front end of an amp.
Otherwise, the amp must have a 775mV sensitivity..
Bonsoir Wahab,
My amps will be some kind of monoblocs (perhaps stereo) without source selection and volume control (for 7.1 use and speaker multiamp with active crossover), I need some.
They are to be fed by the output of any preamp (I may change sources as explained)
I just checked my RX-V659 from Yamaha provide on RCA up to 2V whereas its sensitivity is about 0.2V.
Already some gain inside preamp.
So 1V seems a good target. Above that, clipping is ok...
My amps will be some kind of monoblocs (perhaps stereo) without source selection and volume control (for 7.1 use and speaker multiamp with active crossover), I need some.
They are to be fed by the output of any preamp (I may change sources as explained)
I just checked my RX-V659 from Yamaha provide on RCA up to 2V whereas its sensitivity is about 0.2V.
Already some gain inside preamp.
So 1V seems a good target. Above that, clipping is ok...
Unfortunatly, this is an english speaking site, so
i can t give you the relevant infos in french..
Anyway, 1V sensitivity for an amp in XLR mode
often used by many manufacturers, so yes, it s adequate..
i can t give you the relevant infos in french..
Anyway, 1V sensitivity for an amp in XLR mode
often used by many manufacturers, so yes, it s adequate..
OK, I seem to have misunderstood you.
So, for a domestic hi-fi amplifier... Surveying the market of commercially available amplifiers it is very normal that unbalanced inputs (via RCA / phono connectors) are 1V RMS for full output. (Some years ago it was normally 775mV).
For balanced inputs (via XLR connectors) many amps seem to use 1V per phase (obviously in anti-phase... so pin 2 = +1V when pin 3 = -1V).
Also:
1) Most digital sources (eg. CD player) have a standard 2V output. So pre-amplifier needs attenuation not gain!
2) On your XLR connector please consider that pin 1 is best connected directly to chassis ground, not audio ground.
Regards,
G.
xlr connector
Thanks Wahab, Gordy for straight answers. Personally not building a commercial amp, but might buy a used one, the only US made amps I see for sale seem to have XLR for Public Address use (bars, religious buildings). In a related issue, star grounding (as opposed to ground loops through the signal returns and the safety grounds) is appropriate to eliminate hum. Do bands that have all instruments run through the mixer/PA cut all the safety grounds of the instruments (for example, keyboards, synths) at the local power plug and run them through the shield of the XLR connector to the PA that would be safety grounded to the Mains voltage safety ground? I realize your average bar might be hit and miss, but pro stages like concert halls will have a building engineer that will enforce some kind of standard. What is it?
Thanks Wahab, Gordy for straight answers. Personally not building a commercial amp, but might buy a used one, the only US made amps I see for sale seem to have XLR for Public Address use (bars, religious buildings). In a related issue, star grounding (as opposed to ground loops through the signal returns and the safety grounds) is appropriate to eliminate hum. Do bands that have all instruments run through the mixer/PA cut all the safety grounds of the instruments (for example, keyboards, synths) at the local power plug and run them through the shield of the XLR connector to the PA that would be safety grounded to the Mains voltage safety ground? I realize your average bar might be hit and miss, but pro stages like concert halls will have a building engineer that will enforce some kind of standard. What is it?
Ground loops are generaly a nightmare for the sound engineer.
With my band, we used XLR for all instruments.
The instruments that have assymetric outputs were plugged in a DI box
(direct insert) that did provide a symetrization of the signal before
being sent to the mixing console.
Thanks for discussion of band grounding. I was wondering why no coupler transformers for changing single ended instruments to differential XLR were showing up on the resale market. I will now look for and read up on "DI box" s.
Removing the ground pin from anything is dangerous and illegal in most of the civilized world, dont do it unless you can handle being responsible for death and dont mind jail time.
just because a piece of gear has a XLR connector does not insure its ballanced or pro level (as mentioned earlier real pro gear is 14db hotter than consumer gear (as well as being ballanced)). There are many ways to ballance ins and outs and only transformers give true isolation and therefore ground loop immunity. The same goes for DI boxes. The down side; good audio transformers cost a lot.
I emailed Bill Whitlock (President) of Jensen Transformers asking him if I could distribute one of his papers "UNDERSTANDING, FINDING, & ELIMINATING GROUND LOOPS IN AUDIO & VIDEO SYSTEMS" on this site. I was expecting (if anything) a reply from one of his lackies, this is what I got.
"Thank you very much for writing and I deeply appreciate your very kind
words. I apologize for taking so long to reply - I returned from the New
York AES convention last October with the worst flu I've ever had (might
have been H1N1) and I'm still working on a backlog of Jensen tech support
work that started building up then!
The 40-page handout you refer to is a free download for anyone at the Jensenwebsite
http://www.jensen-transformers.com/an/generic seminar.pdf
(a newer version will take its place soon). Feel free to post a link to it or post
the entire pdf file - I want to reach as many as possible with this
information. For actual recordings of my seminars, I highly recommend the
free (to AES members) streaming presentations, at
AES Tutorials, of my "High-Performance Balanced Interfaces"
master class and (to be posted in a few days) my "Hum, Buzz & Ground Loops" tutorial, both recorded at the 126th AES convention last year in Munich. The recording and editing is excellent ... thanks to Michael Williams of AES!
As always, let me know if you have any questions. And Happy New Year!
Cordially,
Bill Whitlock, president & chief engineer
Jensen Transformers, Inc.
www.jensen-transformers.com"
There is a lot of other great audio info on there site.
just because a piece of gear has a XLR connector does not insure its ballanced or pro level (as mentioned earlier real pro gear is 14db hotter than consumer gear (as well as being ballanced)). There are many ways to ballance ins and outs and only transformers give true isolation and therefore ground loop immunity. The same goes for DI boxes. The down side; good audio transformers cost a lot.
I emailed Bill Whitlock (President) of Jensen Transformers asking him if I could distribute one of his papers "UNDERSTANDING, FINDING, & ELIMINATING GROUND LOOPS IN AUDIO & VIDEO SYSTEMS" on this site. I was expecting (if anything) a reply from one of his lackies, this is what I got.
"Thank you very much for writing and I deeply appreciate your very kind
words. I apologize for taking so long to reply - I returned from the New
York AES convention last October with the worst flu I've ever had (might
have been H1N1) and I'm still working on a backlog of Jensen tech support
work that started building up then!
The 40-page handout you refer to is a free download for anyone at the Jensenwebsite
http://www.jensen-transformers.com/an/generic seminar.pdf
(a newer version will take its place soon). Feel free to post a link to it or post
the entire pdf file - I want to reach as many as possible with this
information. For actual recordings of my seminars, I highly recommend the
free (to AES members) streaming presentations, at
AES Tutorials, of my "High-Performance Balanced Interfaces"
master class and (to be posted in a few days) my "Hum, Buzz & Ground Loops" tutorial, both recorded at the 126th AES convention last year in Munich. The recording and editing is excellent ... thanks to Michael Williams of AES!
As always, let me know if you have any questions. And Happy New Year!
Cordially,
Bill Whitlock, president & chief engineer
Jensen Transformers, Inc.
www.jensen-transformers.com"
There is a lot of other great audio info on there site.
Wahab, Gordy,
Thank you for your input. I may manage a input voltage once it is more clearly defined. I will assume 1Vrms for RCA and 2Vrms for XLR. This way I will take some margin for XLR and that will in fact ease my input design if I have some attenuation on XLR path.
Thank you for your support. Have to spice that.
Regards
Laurent
Thank you for your input. I may manage a input voltage once it is more clearly defined. I will assume 1Vrms for RCA and 2Vrms for XLR. This way I will take some margin for XLR and that will in fact ease my input design if I have some attenuation on XLR path.
Thank you for your support. Have to spice that.
Regards
Laurent
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