Re: Re: Caps on Output
Can’t argue with that, 2.5-3 watts is just not enough to drive bass except in the most limited of manner. Yes, the SI amp is strictly entry level into good sounding class D. It makes sense only as a starting point unless you have very efficient speakers. I haven’t played around with a 41Hz amp yet but the superior parts quality alone should make a big difference.
I will certainly agree that these little things do some things so right it amazes. Probably the first time I ever heard piano note attack and decay sound real and right. This was only true if driving a quality single driver speaker of reasonable efficiency (87db I think).
The point I was trying to make was that in this case the problem may not be power related but some other factor. My little amp will only do 5.5 watts before it starts to clip but has no problem doing deep tuneful bass till you push it. Not a problem as I use it for near field listening. I am sure having regulated SMPS power is a factor here. It does flesh out the bass and give it some body. Sure doesn’t hurt the sound stage either.
Roger
mb said:
Can’t argue with that, 2.5-3 watts is just not enough to drive bass except in the most limited of manner. Yes, the SI amp is strictly entry level into good sounding class D. It makes sense only as a starting point unless you have very efficient speakers. I haven’t played around with a 41Hz amp yet but the superior parts quality alone should make a big difference.
I will certainly agree that these little things do some things so right it amazes. Probably the first time I ever heard piano note attack and decay sound real and right. This was only true if driving a quality single driver speaker of reasonable efficiency (87db I think).
The point I was trying to make was that in this case the problem may not be power related but some other factor. My little amp will only do 5.5 watts before it starts to clip but has no problem doing deep tuneful bass till you push it. Not a problem as I use it for near field listening. I am sure having regulated SMPS power is a factor here. It does flesh out the bass and give it some body. Sure doesn’t hurt the sound stage either.
Roger
George,
I would be interested if you could post a schematic of the output stage (or nearly complete output stage. I am also running the T-amp with 15 ohm speakers - Rogers LS3/5A. The amp is poerful enough for non party listening but I'm trying to improve it -
I have changed - changed input caps to 2.2 uF Wima MKS (Polyester?) bypassed with arcotronics .047uF
- added 4,700uf ELNA Cerafine cap bypasses with panasonic FC 1200uF (remotely wired to power pins of SI chip - not such a good implementation as directly at pins I know
- removed EMI reduction cap accross speaker output posts
Although the sound is good I still find it lacks stage and depth _ I'm running on 7ah battery so should be enough power
I thought maybe changing the cap you mentioned in quote might be the next job
John
I would be interested if you could post a schematic of the output stage (or nearly complete output stage. I am also running the T-amp with 15 ohm speakers - Rogers LS3/5A. The amp is poerful enough for non party listening but I'm trying to improve it -
I have changed - changed input caps to 2.2 uF Wima MKS (Polyester?) bypassed with arcotronics .047uF
- added 4,700uf ELNA Cerafine cap bypasses with panasonic FC 1200uF (remotely wired to power pins of SI chip - not such a good implementation as directly at pins I know
- removed EMI reduction cap accross speaker output posts
Although the sound is good I still find it lacks stage and depth _ I'm running on 7ah battery so should be enough power
I thought maybe changing the cap you mentioned in quote might be the next job
John
Question of staging
Btw I don't recommend bypassing coupling caps as this causes a time smear of the signal and leads to stage placement confusion or a perceived out of focus sound. This is somewhat the same effect as clock jitter, a timing error. Splitting a signal into 2 or more paths is never a good idea as when it is put back together it is never the same as it was originally.
Roger
Sound staging is generally related to power source. The stiffer, better regulated the source the wider the stage. This has to do with cross talk degrading channel separation. Depth almost totally relates to noise. Noise masks low level info and can reduce stage depth dramatically. Focus within the stage relates to signal coherence, dealing with the timing accuracy of leading and trailing edges. The difference of sound arrival times is what we use to locate where in space a sound is coming from. So if all that is true it looks as if you have some power supply work to do. Later I will be building a battery powered piece and will use a highly regulated DC/DC converter. As I haven’t actually listened to this combo yet I don’t know if it will solve all the battery problems/issues. You might try a very large cap to see what happens. Like one of the .1 farad units they use in cars. All those very big caps must be doing some good or they wouldn’t be selling as they are. Let us know your findings.jkeny said:
Btw I don't recommend bypassing coupling caps as this causes a time smear of the signal and leads to stage placement confusion or a perceived out of focus sound. This is somewhat the same effect as clock jitter, a timing error. Splitting a signal into 2 or more paths is never a good idea as when it is put back together it is never the same as it was originally.
Roger
Re: Question of staging
you mean the 1.0 F caps they use in cars. they main reason they sell is because of good marketing, but that's off topic... like you said, sound staging is related to the power source. a regulated power supply greatly improves not only the frequency response (you will hear more bass and smoother highs) but also the sound staging of the SI. find a higher voltage wall wart with ample current capability around the house, buy a good low dropout IC regulator from national or linear, build a simple regulator circuit described in the common applications section of the data sheet, and you're good to go.
sx881663 said:
you mean the 1.0 F caps they use in cars. they main reason they sell is because of good marketing, but that's off topic... like you said, sound staging is related to the power source. a regulated power supply greatly improves not only the frequency response (you will hear more bass and smoother highs) but also the sound staging of the SI. find a higher voltage wall wart with ample current capability around the house, buy a good low dropout IC regulator from national or linear, build a simple regulator circuit described in the common applications section of the data sheet, and you're good to go.
Re: Re: Question of staging
The message I wanted to give was dealing with power supplies. If you purchase a good quality SMPS type unit, one that has its own power cord. There are usually screws under the stick on feet or label to open it up. These units are usually adjustable and if not can be easily be made so. While you are at it you can up grade the caps with some larger low ESR units. These units usually have very good regulation using an lm431 reference as a high gain feed back element. It makes it not worth the bother to build one that wouldn’t be as good anyway. Several more real advantages exist with these units aside from regulation and efficiency. Due to a very small influence from leakage inductance in their transformers and the high speed switching they are very quiet in the audio band. They respond fast to changes but run out of steam just as fast so for a 12 - 13.5 v unit I would recommend a 22-50,000uf buffer cap. At 16 volt rating these aren’t too big. It can be done with 2 smaller pieces in parallel and put into the battery compartment of the original case, if that is what you are using. With this being done sound staging will not be a problem.
Roger
I agree with the good marketing bit, putting gold plated screws into them along with a fancy label and charging twice as much. But all that aside they must do some good or the "fad" would have died out.BWRX said:
The message I wanted to give was dealing with power supplies. If you purchase a good quality SMPS type unit, one that has its own power cord. There are usually screws under the stick on feet or label to open it up. These units are usually adjustable and if not can be easily be made so. While you are at it you can up grade the caps with some larger low ESR units. These units usually have very good regulation using an lm431 reference as a high gain feed back element. It makes it not worth the bother to build one that wouldn’t be as good anyway. Several more real advantages exist with these units aside from regulation and efficiency. Due to a very small influence from leakage inductance in their transformers and the high speed switching they are very quiet in the audio band. They respond fast to changes but run out of steam just as fast so for a 12 - 13.5 v unit I would recommend a 22-50,000uf buffer cap. At 16 volt rating these aren’t too big. It can be done with 2 smaller pieces in parallel and put into the battery compartment of the original case, if that is what you are using. With this being done sound staging will not be a problem.
Roger
Big caps!
General information
I just did some checking on eBay for some larger 16 volt caps but the selection was very limited. Thought maybe searching for car type caps using the word farad would bring up something. Wow! Did it ever 7+ pages of caps from .5 farad to 60, yes 60 farad. These are apparently a hybrid design with no further info available. Not cheap either. These caps must have some merit in this application.
Roger
General information
I just did some checking on eBay for some larger 16 volt caps but the selection was very limited. Thought maybe searching for car type caps using the word farad would bring up something. Wow! Did it ever 7+ pages of caps from .5 farad to 60, yes 60 farad. These are apparently a hybrid design with no further info available. Not cheap either. These caps must have some merit in this application.
Roger
Thanks for your help - ypu are right it was the a power supply problem - even though I am using a 7aH SLA battery I put a 4700uF ELNA capacitor on fly leads connected to the pos and ground of the SI chip.
Once I took this out and put a low ESR panasonic FC cap right at the chip power pins everything sharpened up and sound stage opened up.
I am finding that the mid range is not as full as other amps I have heard (gainclone, etc). Has any else experienced this or is it the synergy with my 15 ohm speakers?
John
Once I took this out and put a low ESR panasonic FC cap right at the chip power pins everything sharpened up and sound stage opened up.
I am finding that the mid range is not as full as other amps I have heard (gainclone, etc). Has any else experienced this or is it the synergy with my 15 ohm speakers?
John
John,
I am using Auricaps for my input coupling chores. These caps are exemplary in all respects including test results. I also am using small full range single drivers (Tang band 8 ohm 3”) in near field with a powered sub. Earlier when I tried quality 2 way speakers the sound all around the cross over freq was pretty bad. These amps can’t handle complex loads with varying impedance, probably because the output filter is not in the feedback loop. As it stands it sounds wonderful and the midrange on up is its strongest good point. If you are stuck driving complex speakers then you might try upgrading the output filter components and change them to the proper value for 16 ohm. Tripath has all that info on their website.
Roger
I am using Auricaps for my input coupling chores. These caps are exemplary in all respects including test results. I also am using small full range single drivers (Tang band 8 ohm 3”) in near field with a powered sub. Earlier when I tried quality 2 way speakers the sound all around the cross over freq was pretty bad. These amps can’t handle complex loads with varying impedance, probably because the output filter is not in the feedback loop. As it stands it sounds wonderful and the midrange on up is its strongest good point. If you are stuck driving complex speakers then you might try upgrading the output filter components and change them to the proper value for 16 ohm. Tripath has all that info on their website.
Roger
Roger,
Thanks, that was what I was thinking, although I will probably try to go the route of using the amps( I have two) to make these speakers active using computer and kxproject or BruteFir software for digital crossovers - this will remove the complex passive crossover s used on Ls3/5a's and may free up the sound
John
Thanks, that was what I was thinking, although I will probably try to go the route of using the amps( I have two) to make these speakers active using computer and kxproject or BruteFir software for digital crossovers - this will remove the complex passive crossover s used on Ls3/5a's and may free up the sound
John
Bi amp
This is not an easy one. The Rogers have an extensive and complex crossover network. This would be a very good place for reverse engineering and circuit modeling. It would also be helpful to have the specs on the drivers used, to plug into the model. This would tell you what they are doing but not necessarily why. With a computer generated crossover and correction it should be possible to overcome the back row seat sound these speakers have. One real and immediate benefit would be the much better efficiency and control from direct drive. I think an excellent use for these amps. This could be very good when finished. Let us know as you progress.
Good luck,
Roger
This is not an easy one. The Rogers have an extensive and complex crossover network. This would be a very good place for reverse engineering and circuit modeling. It would also be helpful to have the specs on the drivers used, to plug into the model. This would tell you what they are doing but not necessarily why. With a computer generated crossover and correction it should be possible to overcome the back row seat sound these speakers have. One real and immediate benefit would be the much better efficiency and control from direct drive. I think an excellent use for these amps. This could be very good when finished. Let us know as you progress.
Good luck,
Roger
Low bass problem found in my system.
My issue with the bottom end ended up being elsewhere. My preamp is balanced out only and uses homemade interconnects to convert it to single ended.
In my haste to make a new pair the + and - got swapped in one. The imaging was bad and center fill mucked up. But the real issue was the bass was rolling off. Deep bass seems to cancel when one driver is moving out as the other moves in.
Now my battery powered, mono'ed SI has fine low end response. I expected it to be this way from the start.
The ideas that it was lack of current had me looking inside the amp. But the 2 batteries and the caps should slam much more juice than my 15 ohm, 100 dB efficient speakers can take.
I tried another amp that needed different interconnects and since it had good strong low bass thought it was the T amps sonic signature. I had just about given up on the T amps as serious audio toys.
George
My issue with the bottom end ended up being elsewhere. My preamp is balanced out only and uses homemade interconnects to convert it to single ended.
In my haste to make a new pair the + and - got swapped in one. The imaging was bad and center fill mucked up. But the real issue was the bass was rolling off. Deep bass seems to cancel when one driver is moving out as the other moves in.
Now my battery powered, mono'ed SI has fine low end response. I expected it to be this way from the start.
The ideas that it was lack of current had me looking inside the amp. But the 2 batteries and the caps should slam much more juice than my 15 ohm, 100 dB efficient speakers can take.
I tried another amp that needed different interconnects and since it had good strong low bass thought it was the T amps sonic signature. I had just about given up on the T amps as serious audio toys.
George
Phase inversion
George,
In my younger days I had a decent setup and liked to show it off. I had done extensive upgrades to about every thing including the speakers. I had recently made acquaintance with a speaker designer and invited him over for a listen. He sat there with a rather puzzled expression on his face and calmly told me how much better it would sound if the tweeters weren’t out of phase, rather embarrassing. Wow what a change when I found the screw up and fixed it. Been there done that!
Been reading how some have found the inductor upgrades are very significant. Yours must have a sweet sound with those inductors you are using.
Roger
George,
In my younger days I had a decent setup and liked to show it off. I had done extensive upgrades to about every thing including the speakers. I had recently made acquaintance with a speaker designer and invited him over for a listen. He sat there with a rather puzzled expression on his face and calmly told me how much better it would sound if the tweeters weren’t out of phase, rather embarrassing. Wow what a change when I found the screw up and fixed it. Been there done that!
Been reading how some have found the inductor upgrades are very significant. Yours must have a sweet sound with those inductors you are using.
Roger
SI problems with 15ohm speakers
Just an update on my problems with Si & Rogers 15ohm speakers (see above) - I have solved the issue of thin mid band. I had replaced input cap with WIMA 2.2uF caps connected by twisted cat 5 wire to SI board but I had bypassed input inductor and resistor & cap to ground that existed on SI board. Once I made the right connections the sound is now exquisite.
Resistor & cap to ground on input affects the high freq response of the circuit - I should have remembered this.
Oh the problems of being an audio electronics learner
John
Just an update on my problems with Si & Rogers 15ohm speakers (see above) - I have solved the issue of thin mid band. I had replaced input cap with WIMA 2.2uF caps connected by twisted cat 5 wire to SI board but I had bypassed input inductor and resistor & cap to ground that existed on SI board. Once I made the right connections the sound is now exquisite.
Resistor & cap to ground on input affects the high freq response of the circuit - I should have remembered this.
Oh the problems of being an audio electronics learner
John
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.