[Manolo]

Their input sensitivity is rather low which translates into high gain. Why would this be necessary. Most of the users use them with Odyssey preamplifiers which are active. I audiioned an amplifier with similar gain in my system the other day and because my preamp is acrather high gain design the volume control travel was very limited. Can thse be ordered with less gain?  Thanks.

[JackD]

I have owned multiple models of Odyssey amps over the last 15 years and I always found their input sensitivity to be about average at 1v.  On the other hand, many "modern" preamps, especially tube models have entirely to much gain.  Odyssey's own preamps have between 14-16db of gain and work well as have many others I have used in this range.  If you are attempting to use a preamp with a high gain number like CJ's mid-20's you are going to have problems with a lot of amps. As to having it changed you need to call Klaus directly.

[G Georgopoulos]

I would think is have to do with different sources,vinyl o/p voltage is much less than cd

[RDavidson]

Yes. It seems high gain is really rather common for many manufacturers. I guess this means it is "normal" not high. Symantics aside, why do many amps have a 1V input sensitivity? With a great number of speakers with sensitivity in the 85db @ 1 watt/meter range and higher, anything less than 2V input sensitivity really doesn't make sense......especially when one considers the prevalence of active preamps with plenty of gain and sources that commonly have at least 2V output.

Is there a reason to have less than 2V input sensitivity on an amp? With the info above in consideration, it would be a larger problem (as the OP has pointed out) of having too much gain and volume potentiometers not ever working in their optimal range to be a common issue, than ever not having enough gain.

[G Georgopoulos]

Yes. It seems high gain is really rather common for many manufacturers. I guess this means it is "normal" not high. Symantics aside, why do many amps have a 1V input sensitivity? With a great number of speakers with sensitivity in the 85db @ 1 watt/meter range and higher, anything less than 2V input sensitivity really doesn't make sense......especially when one considers the prevalence of active preamps with plenty of gain and sources that commonly have at least 2V output.

Is there a reason to have less than 2V input sensitivity on an amp? With the info above in consideration, it would be a larger problem (as the OP has pointed out) of having too much gain and volume potentiometers not ever working in their optimal range to be a common issue, than ever not having enough gain.

in regard to preamp you stated,it does nothing to pwramp sensitivity,a gain of 2 may make the 1v 2v
which seems right closer to cd level but the cd then becomes 4v,this will clip the pwramp...

on second thought,one way to equilyse the inputs on a preamp is to attenuate the cd level
down to 1v with a couple of resistors,but you have to have different inputs and selector swicth
for cd and line inputs

cheers...

[Chops]

I've run six different amps on my system, including my Khartago Kismet, and all of them have pretty much the same amount of gain.

[RDavidson]

in regard to preamp you stated,it does nothing to pwramp sensitivity,a gain of 2 may make the 1v 2v
which seems right closer to cd level but the cd then becomes 4v,this will clip the pwramp...

on second thought,one way to equilyse the inputs on a preamp is to attenuate the cd level
down to 1v with a couple of resistors,but you have to have different inputs and selector swicth
for cd and line inputs

cheers...

Right. I think you're seeing my point. With so much gain, one may end up attenuating the output voltage from the source A LOT......and may even have to use resistors in line. Why not just design the amps to have 2V input sensitivity, vs making people have to deal with it? I don't understand the reason for 1V. I recently saw an amp with 860mV input sensitivity. There has to be a design decision behind this.

[G Georgopoulos]

There has to be a design decision behind this.

for sure.i see your point...

[Davey]

I think you'll find power amplifiers fairly standardized now with regard to voltage gain.  29db was made a requirement for THX-certified (and other) setups.  The reason the sensitivity ratings vary is because the power ratings vary.  It makes complete sense.  I'm not sure why this is puzzling.
I find this aspect of power amplifier design welcomeingly simple in the complicated mess of audio equipment we currently have access to.

Preamp voltage gain is quite another subject though.    Many of them have too darn much gain in the line-amp section which makes for a hair-trigger volume control in many instances.  I repaired an Audible Illusions Modulus 2 awhile back.  Two, separate, volume controls which never got past the 9 o'clock position because of 30db gain in the line-amp section.  What a horrible piece of equipment....useability-wise.

Dave.

[RDavidson]

I think you'll find power amplifiers fairly standardized now with regard to voltage gain.  29db was made a requirement for THX-certified (and other) setups.  The reason the sensitivity ratings vary is because the power ratings vary.  It makes complete sense.  I'm not sure why this is puzzling.
I find this aspect of power amplifier design welcomeingly simple in the complicated mess of audio equipment we currently have access to.

Preamp voltage gain is quite another subject though.    Many of them have too darn much gain in the line-amp section which makes for a hair-trigger volume control in many instances.  I repaired an Audible Illusions Modulus 2 awhile back.  Two, separate, volume controls which never got past the 9 o'clock position because of 30db gain in the line-amp section.  What a horrible piece of equipment....useability-wise.

Dave.

No it doesn't make complete sense. I've seen amplifiers with the same output rating, but different input voltage sensitivity. Perhaps I'm missing sonething here? It seems to me that it is a design decision, keeping in mind the input stage of an amp is separate from the output stage ; Same with active preamps.

[G Georgopoulos]

Preamp voltage gain is quite another subject though.    Many of them have too darn much gain in the line-amp section which makes for a hair-trigger volume control in many instances.  I repaired an Audible Illusions Modulus 2 awhile back.  Two, separate, volume controls which never got past the 9 o'clock position because of 30db gain in the line-amp section.  What a horrible piece of equipment....useability-wise.

Dave.

100% with agreement to you sir ....

[poseidonsvoice]

No it doesn't make complete sense. I've seen amplifiers with the same output rating, but different input voltage sensitivity. Perhaps I'm missing sonething here? It seems to me that it is a design decision, keeping in mind the input stage of an amp is separate from the output stage ; Same with active preamps.

Please show us examples.

Best,
Anand.

[Davey]

No it doesn't make complete sense. I've seen amplifiers with the same output rating, but different input voltage sensitivity. Perhaps I'm missing something here? It seems to me that it is a design decision, keeping in mind the input stage of an amp is separate from the output stage ; Same with active preamps.

There are exceptions.  That's why I said "fairly standardized."    But the vast majority will be in the 28-29db gain range......regardless of power rating.
Currently, the Hypex amplifiers are 26db gain, some amplifiers in the professional world are 32db gain, etc, etc.  So...... 

Dave.

[RDavidson]

Please show us examples.

Best,
Anand.

Here are some examples.

The Belles 150A Reference's input sensitivity is 1.27 V to reach full output power of 125 wpc into 8 ohms.

The McCormack DNA 125 has an input sensitivity of 1 V to reach full output power of 125 wpc into 8 ohms.

The Parasound HCA 1000A has an input sensitivity of 1 V for 28.28 V, THX Reference Level; 1.1 V for full output of 125 wpc into 8 ohms.

The Emotiva UPA 200 has an input sensitivity of 1 V to reach full output of 125 wpc into 8 ohms.

.....and here are a couple more examples of 100 wpc amps

The Adcom GFA 545 has an input sensitivity of 1.25 V to reach full output of 100 wpc into 8 ohms

The Muse Model 100 has an input sensitivity of 890 mV to to reach full output of 100 wpc into 8 ohms

So, while a variance of roughly 25 V to approaching .5 V may seem trivial, it isn't with consideration to the average efficiency of most speakers today (typically 85 db - 88 db sensitive) and that most people don't have cavernous listening spaces. Throw in an active preamp and one may not be able to even listen past the 9:00-10:00 position on the volume knob most of the time. Heck, even a simple potentiometer based passive preamp may not be great, considering most modern sources output at least 1 V, typically closer to 2 V (possible impedance issues aside). Not to get into a discussion on preamps, but there can be a lot of problems in this. I believe this is pretty common scenario.

[RDavidson]

There are exceptions.  That's why I said "fairly standardized."    But the vast majority will be in the 28-29db gain range......regardless of power rating.
Currently, the Hypex amplifiers are 26db gain, some amplifiers in the professional world are 32db gain, etc, etc.  So...... 

Dave.

Yes, you're right. I guess I can only conclude that amp manufacturers target roughly 1V input sensitivity to ensure the amp doesn't stress the source component's output stage to reach full output......which circles back to having too much gain. Personally, I would be surprised if I used more than .2 V of gain. That's likely louder than comfortable too. Everyone's systems and preferences are different, but too much gain seems to be a larger problem than not having enough 99% of the time.

[barrows]

This is one of the reasons I love DIY!  Mismatched gain in systems leaves a lot of the performance one pays for behind, as having to use >20-30 dB of attenuation is ridiculous, and raises the noise floor way beyond what it really needs to be in a well matched (for gain) system.
The above post which mentions THX standards is right.  Some amp manufacturers which want to be in the HT market, like Emotiva and Parasound require THX certs for marketing purposes, hence the high gain.  I remeber John Curl remarking that Parasound required all their amps he designed to be THX certified.
I sure am glad my DIY nCore amps require 2V for full output.  Then I build my DAC to output about 2.1V at 0dB, and I end up using volume levels from -20dB to -2dB depending on source levels (current compressed recordings usually requiring the higher attenuation levels).
One company which gets this right is Ayre, their amps have around 24-26 dB gain, and their preamps have user adjustable gain by swapping a single resistor in each channel, which is mounted via screw terminals.  When I had the Ayre K5-XeMP preamp in my system I adjusted its gain down to about 2 dB or so, for a nice performance improvement.
High gain results in a higher noise floor, which is just a shame, and high levels of attenuation reduce resolution whether the volume control is analog (resistive) or digital.  If necessary, the easiest solution is to put a high quality resistor pad right at the input of the amp, or use a transformer style attenuation which performs well at high attenuation levels (but still adds distortion).

[germay0653]

Does anyone know if the new Khartago faceplates, with the Odyssey logo, can be changed out for the old ones with just the LED?