Hi all,
Im having issues finding a amp that will work with my high efficiency horn speakers without generating far too much noise. Even when the preamp is dissconnected, the white noise is really quite loud- could anyone suggest what to look for or another solution?- possibly reducing the apparent sensitivity seen by the amp by running a parallel resistor as a load?
Thanks guys!
Im having issues finding a amp that will work with my high efficiency horn speakers without generating far too much noise. Even when the preamp is dissconnected, the white noise is really quite loud- could anyone suggest what to look for or another solution?- possibly reducing the apparent sensitivity seen by the amp by running a parallel resistor as a load?
Thanks guys!
Hi,
Theoretically connecting a preamp can reduce the noise of a power amplifier,
though its not hard to design a power amplifier where the pre-amp will totally
dominate the noise level coming out of the speakers.
Shorting the power amplifier inputs gives you its intrinsic noise.
Hard to say without further details, but reducing the closed loop
gain of the power amplifier will reduce noise levels commeasurantly.
Poor gain structure is often the cause of high no signal noise.
rgds, sreten.
Theoretically connecting a preamp can reduce the noise of a power amplifier,
though its not hard to design a power amplifier where the pre-amp will totally
dominate the noise level coming out of the speakers.
Shorting the power amplifier inputs gives you its intrinsic noise.
Hard to say without further details, but reducing the closed loop
gain of the power amplifier will reduce noise levels commeasurantly.
Poor gain structure is often the cause of high no signal noise.
rgds, sreten.
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There seams little or no difference in the white noise I get with the preamp connected, dissconnected, source on or off, or even between tracks on a song, so this is an amp issue I think. Are there any particular amplifiers that would have low self noise ?
The speakers are 115db/1watt. So I appreciate that there's nothing wrong with the amp realy, it's just a big ask!
The speakers are 115db/1watt. So I appreciate that there's nothing wrong with the amp realy, it's just a big ask!
Ummm... 115dB/1w??
Please tell us more... what speakers are these??
Are you hearing a *hiss*??
Hum??
Higher harmonics of hum?
How loud is it?
In order to get low noise, you will need to use an amp that has: A) a low noise power supply, B) uses an input stage with low self noise, C) is likely going to have a very good PSRR as well...
Having said all that and waiting to find out about what your present amp and speakers are (very curious) - pix would be nice too! - I have used the F5 on my 109dB/1w/1m compression driver/horns that run from 300Hz up to ~12kHz or so and have heard zip noise (which is very nice). However these had a very clean power supply... but there was no residual HF noise to be heard.
I am sure many other designs will have nil background noise...
Some amps publish a S/N or noise floor figure... even so that is very very far below typical listening levels. However it is nice to perceive nothing except music.
Be sure to check the amp with the inputs shorted to be certain. Don't make a mistake
doing that, with high sensitivity speakers like those a mistake will be deafening!!
_-_-bear
Please tell us more... what speakers are these??
Are you hearing a *hiss*??
Hum??
Higher harmonics of hum?
How loud is it?
In order to get low noise, you will need to use an amp that has: A) a low noise power supply, B) uses an input stage with low self noise, C) is likely going to have a very good PSRR as well...
Having said all that and waiting to find out about what your present amp and speakers are (very curious) - pix would be nice too! - I have used the F5 on my 109dB/1w/1m compression driver/horns that run from 300Hz up to ~12kHz or so and have heard zip noise (which is very nice). However these had a very clean power supply... but there was no residual HF noise to be heard.
I am sure many other designs will have nil background noise...
Some amps publish a S/N or noise floor figure... even so that is very very far below typical listening levels. However it is nice to perceive nothing except music.
Be sure to check the amp with the inputs shorted to be certain. Don't make a mistake
doing that, with high sensitivity speakers like those a mistake will be deafening!!
_-_-bear
mid driver is- a JBL 2452sl...(lucky me!)
http://www.jblproservice.com/pdf/Discrete Sales Models/2452HJ.pdf
in a JMLC 350hz horn.
speakers are active, and the crossover is software based at the source end (JRiver media player) so no crossover components to soak up the efficiency- unfortunately this would actually be a good thing in this case!
Yup, noise is a hiss.
Photos wouldnt do any justice as they arnt assembled in any real way at the moment.
The finished thing should be somthing like this-
Im running a tripath class D amp at the moment, so i appreciate this isnt going to be the best, but i have also tried several other amplifiers that proved marginly better- but not anything like good enough.
http://www.jblproservice.com/pdf/Discrete Sales Models/2452HJ.pdf
in a JMLC 350hz horn.
speakers are active, and the crossover is software based at the source end (JRiver media player) so no crossover components to soak up the efficiency- unfortunately this would actually be a good thing in this case!
Yup, noise is a hiss.
Photos wouldnt do any justice as they arnt assembled in any real way at the moment.
The finished thing should be somthing like this-
Im running a tripath class D amp at the moment, so i appreciate this isnt going to be the best, but i have also tried several other amplifiers that proved marginly better- but not anything like good enough.
You may or may not find the xover to be your weak link later...
But you should not be hearing any hiss from the 111dB/1w neodymium JBL drivers... it is doubtful that the rest of the system can maintain this sensitivity, in which case (as is usually the case) the HF horn is reduced in level to meet the lower drivers...
Again, the test is invalid unless you have shorted the input to the amp. Even with the "volume" on whatever comes before the amp turned all the way down, there is still a line stage or buffer between it and the amp. It is unclear to me if ur tripath amp has a level control and where it is or how it works (is it digital, or analog and if analog where in the circuit?).
Again, I use 109dB/1w compression drivers and have not had this problem.
I suggested the F5 as being very nice, although it needs extra gain to match to a standard amp, otoh since most compression drivers need to be knocked down in level, this works fine. In my system that is 9-10dB so I get an almost perfect match to my lower mid drivers running at 99-100dB...
I would suggest almost any good pure class A amp for this, and it only needs to be a few watts for this application, as in 15-40 watts is quite sufficient. 10 watts is sufficient, even 5 watts will work fine since 1 watt produces a screaming 111dB near the horn! You want pure class A, as any crossover distortion (low level, low power, where one transistor crosses to another) will be of major concern at normal listening levels. Most of the time you will be listening at power levels under 1 watt, unless you like to reproduce the Rolling Stones at concert levels... ok?
I would say go with a SE tube, but you are worried about noise, and it is harder to get a very low noise floor in a tube amp than in a solid state amp, especially comparing the "usual" commercial amps, and the "usual" DIY efforts.
First isolate the source of your hiss... the amp should provide no audible hiss. Inputs shorted.
Btw, and fwiw, the lower drivers look sexy, but zero width baffles may effect the freq response in the 100-350Hz range in a negative way... as will the height above the floor...
Let us know what you hear with the inputs shorted, and with a "regular amp" the same way, and what amp that is?
_-_-bear
But you should not be hearing any hiss from the 111dB/1w neodymium JBL drivers... it is doubtful that the rest of the system can maintain this sensitivity, in which case (as is usually the case) the HF horn is reduced in level to meet the lower drivers...
Again, the test is invalid unless you have shorted the input to the amp. Even with the "volume" on whatever comes before the amp turned all the way down, there is still a line stage or buffer between it and the amp. It is unclear to me if ur tripath amp has a level control and where it is or how it works (is it digital, or analog and if analog where in the circuit?).
Again, I use 109dB/1w compression drivers and have not had this problem.
I suggested the F5 as being very nice, although it needs extra gain to match to a standard amp, otoh since most compression drivers need to be knocked down in level, this works fine. In my system that is 9-10dB so I get an almost perfect match to my lower mid drivers running at 99-100dB...
I would suggest almost any good pure class A amp for this, and it only needs to be a few watts for this application, as in 15-40 watts is quite sufficient. 10 watts is sufficient, even 5 watts will work fine since 1 watt produces a screaming 111dB near the horn! You want pure class A, as any crossover distortion (low level, low power, where one transistor crosses to another) will be of major concern at normal listening levels. Most of the time you will be listening at power levels under 1 watt, unless you like to reproduce the Rolling Stones at concert levels... ok?
I would say go with a SE tube, but you are worried about noise, and it is harder to get a very low noise floor in a tube amp than in a solid state amp, especially comparing the "usual" commercial amps, and the "usual" DIY efforts.
First isolate the source of your hiss... the amp should provide no audible hiss. Inputs shorted.
Btw, and fwiw, the lower drivers look sexy, but zero width baffles may effect the freq response in the 100-350Hz range in a negative way... as will the height above the floor...
Let us know what you hear with the inputs shorted, and with a "regular amp" the same way, and what amp that is?
_-_-bear
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Hi bear,
When you say 'short the amplifier input' I just want to confirm- you are suggesting bridging the + AND - terminals of the power amp rca input (obviously with no source connected)
The amp is a connex unit-
Connexelectronic
mine is a slightly earlyer one, with no vol pot. and the appropriate smps 1000 power supply.
I was under the impression there was no evidence that class A was an audiable advantage over any other??
Up to this point I have owned and used several brand name amps and have found the differences between them subtle at best. Im not knocking any particular brand, its just that Im looking to only spend what I need- so Im looking for the cheapest option that will do the job propperly.
I dont want to cause any arguements over 'this sounds better than that' Its just that I want to stick on solid ground of cheapest proven audiably better only for now.
Could anyone suggest what might be the cheapest <100w amplifier that meets the low noise criteria?
Im also under the impression that a lower output power amp will likely have lower self noise as the gain is less??
When you say 'short the amplifier input' I just want to confirm- you are suggesting bridging the + AND - terminals of the power amp rca input (obviously with no source connected)
The amp is a connex unit-
Connexelectronic
mine is a slightly earlyer one, with no vol pot. and the appropriate smps 1000 power supply.
I was under the impression there was no evidence that class A was an audiable advantage over any other??
Up to this point I have owned and used several brand name amps and have found the differences between them subtle at best. Im not knocking any particular brand, its just that Im looking to only spend what I need- so Im looking for the cheapest option that will do the job propperly.
I dont want to cause any arguements over 'this sounds better than that' Its just that I want to stick on solid ground of cheapest proven audiably better only for now.
Could anyone suggest what might be the cheapest <100w amplifier that meets the low noise criteria?
Im also under the impression that a lower output power amp will likely have lower self noise as the gain is less??
If you have the opportunity, give a try to the Circlophone, I'd be curious to see what the result would be with high efficiency speakers like yours.
That might be interesting, I have launched a thread on the subject, and it would be nice to have the impressions of some more "real life testers":
http://www.diyaudio.com/forums/soli...cted-noise-benefits-circlophone-topology.html
That might be interesting, I have launched a thread on the subject, and it would be nice to have the impressions of some more "real life testers":
http://www.diyaudio.com/forums/soli...cted-noise-benefits-circlophone-topology.html
Hi elvee,
The circlophone sounds a little expensive for what I'm looking for at the moment. Lovely as it looks mind you.
I'm after the cheapest amp to do the job successfully at this point as I just want the system running!
The circlophone sounds a little expensive for what I'm looking for at the moment. Lovely as it looks mind you.
I'm after the cheapest amp to do the job successfully at this point as I just want the system running!
No, you would short the inputs to GROUND.
Not the outputs, the inputs.
Then listen.
IF the amp is making noise, then you will hear only the amp.
You say "cheap". Garbage IN = Garbage OUT?
There may or may not be amps with low self noise that are inexpensive, but I think you are barking up the wrong tree here. With the rather high sensitivity of the HF section you're going to need both a clean and a quiet amp.
There are substantial sonic benefits to class A amps, especially when you can hear the "First Watt" clearly, all the time.
Think about this. For an average in room SPL of say 93dB SPL at 1 m from the speakers, what will your average power be?? Work backwards from 111dB at 1 watt (the driver's spec). I get ~0.035watts, approximately. Most standard bias AB amps are in the xover region 100% of the time at that power level... not a good place to be. Class A? No xover region. Much better.
The only question is how small ur budget is, and what yr ability to build might be.
IF you can't build, then perhaps you can find something built by someone here, or identify a nice low power amp for the tweeter section only.
If you can afford the drivers for the speaker you showed, then I think you can afford to get urself a decent power amp for the top end of your system. Or so it would seem.
I would suggest that you take a look at the F5, it has the nice attribute of sounding very good (set up right) and having 10dB less gain than most amps, so combined in a simple biamp with most amps it makes for an easy level matching between a compression driver and the usual dynamic drivers below... There are other amps. Especially here on this site...
_-_-bear
Not the outputs, the inputs.
Then listen.
IF the amp is making noise, then you will hear only the amp.
You say "cheap". Garbage IN = Garbage OUT?
There may or may not be amps with low self noise that are inexpensive, but I think you are barking up the wrong tree here. With the rather high sensitivity of the HF section you're going to need both a clean and a quiet amp.
There are substantial sonic benefits to class A amps, especially when you can hear the "First Watt" clearly, all the time.
Think about this. For an average in room SPL of say 93dB SPL at 1 m from the speakers, what will your average power be?? Work backwards from 111dB at 1 watt (the driver's spec). I get ~0.035watts, approximately. Most standard bias AB amps are in the xover region 100% of the time at that power level... not a good place to be. Class A? No xover region. Much better.
The only question is how small ur budget is, and what yr ability to build might be.
IF you can't build, then perhaps you can find something built by someone here, or identify a nice low power amp for the tweeter section only.
If you can afford the drivers for the speaker you showed, then I think you can afford to get urself a decent power amp for the top end of your system. Or so it would seem.
I would suggest that you take a look at the F5, it has the nice attribute of sounding very good (set up right) and having 10dB less gain than most amps, so combined in a simple biamp with most amps it makes for an easy level matching between a compression driver and the usual dynamic drivers below... There are other amps. Especially here on this site...
_-_-bear
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If you have the capability to build it yourself, the Circlophone is probably one of the cheapest options possible, and I think Mickeymoose could sell you boards at a very reasonable price.
I cannot guarantee it would be as silent as you want, I am just curious, and I would like to see if observations made by others (including me) are confirmed in an extreme case like yours.
But of course, I can perfectly understand if you do not want to serve as a guinea pig....
Passlabs F1, F2, F3, F4, ZenV4, etc. have noise in the 30 - 50 microvolt region over 20 Hz - 20KHz bandwidth and should fit the bill. At my modest 104dB/W SPL level this is still inaudible - ear on HF horn.
I see you talking about "cheapest" in this thread, then 6 channels class-A mosfet amp shouldn't be an option for you. If you want just running your system then take a look for "Gainclone" threads in chipamp forum.
Look in the Group Buys...?
That and Swap Meet...
Cost will be 6x one channel? 😀
Depends a whole lot on ur skills and what you already have for parts and things like xfrmrs and heatsinks and/or chassis.
Ur using this for home theater??
Seems like it would be best if you layout your system design, what exists and what is actually built so far... hard to advise in a reasonable way when one has to guess.
_-_-bear
That and Swap Meet...
Cost will be 6x one channel? 😀
Depends a whole lot on ur skills and what you already have for parts and things like xfrmrs and heatsinks and/or chassis.
Ur using this for home theater??
Seems like it would be best if you layout your system design, what exists and what is actually built so far... hard to advise in a reasonable way when one has to guess.
_-_-bear
It all depends on price! If a gainclone comes to similar money as a f5 then I would prob go for the f5; but this thinking is a slippery slope!
I tried out a sugden masterclass today, and it was fine- no noise to speak of. I also spent some time with the behringer a500, and I could get the noise to much more acceptable levels, but not quite good enough. The triparh amp doesn't seam to get near.
The six channels would be for the 2 active speakers with 3 drivers each.
Sorry you lost me. Three drivers each?? An amp per driver? Why?
What you posted looked like a two way system to my eyes...
What ARE the non-compression driver drivers??
_-_-bear
What you posted looked like a two way system to my eyes...
What ARE the non-compression driver drivers??
_-_-bear
Jbl 2452sl as mid/tweeter, pair of jbl 2226h bass, as 2 way. Crossover set around 700hz. Later on the plan is to convert to 3 way with a dedicated tweeter that I haven't decided on yet.
The system at the moment is a computer sound card direct into the connex power amps, all running from JRiver media player. JRiver is doing the room eq (calibrated in REW). Crossovers will be done inside JRiver to multiple sound cards or single FireWire external 12channel sound card. Everything below 65hz is sent to my sub, (jbl 2242h) so I suppose it's actually going to be a 4 way system.
The system at the moment is a computer sound card direct into the connex power amps, all running from JRiver media player. JRiver is doing the room eq (calibrated in REW). Crossovers will be done inside JRiver to multiple sound cards or single FireWire external 12channel sound card. Everything below 65hz is sent to my sub, (jbl 2242h) so I suppose it's actually going to be a 4 way system.
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I see... well it seems to me that you will need considerably more power to the mids and the woofers. To match to the horns (assuming you want the same max spl?), which will be scary loud and assuming the realization of 6dB more gain from the parallel connection of a pair of drivers, you'll need about 10-12dB more power. That's if you want the amps to clip at the same time... which isn't really necessary unless you play things crazy loud.
But imo, and depending on the size room, and your distance from the speakers, and what the EQ wants to do (assuming minor corrections of <+3dB, since every 3dB is a doubling of power) you might get away with the usual F5 on all three. I'd want to maybe use the F5X for the lower two and get a little more power... but it might make sense to look at other amps for the cone drivers and use the F5 for the highs only.
You shouldn't hear much noise on the woofers using a rather generic (low cost) pro switching or other bipolar amp... the mids you need to be somewhat more careful...
Some things to think about...
_-_-bear
Btw, with JBLs, and subs, not sure why you need a mid driver set and a woofer driver set, given the reasonably low rolloff point of the horn you showed...
But imo, and depending on the size room, and your distance from the speakers, and what the EQ wants to do (assuming minor corrections of <+3dB, since every 3dB is a doubling of power) you might get away with the usual F5 on all three. I'd want to maybe use the F5X for the lower two and get a little more power... but it might make sense to look at other amps for the cone drivers and use the F5 for the highs only.
You shouldn't hear much noise on the woofers using a rather generic (low cost) pro switching or other bipolar amp... the mids you need to be somewhat more careful...
Some things to think about...
_-_-bear
Btw, with JBLs, and subs, not sure why you need a mid driver set and a woofer driver set, given the reasonably low rolloff point of the horn you showed...
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