OK, I've just about had it and it is time to flame.
I bought not one, but two HLLY Tamp-90's. They are so NOISY with HISS that you cannot listen to them.
I've written at least a dozen letters to the company and the eBay vendor and just keep getting stalled.
Return shipping would be $209 -- cost prohibitive. I get promises of refunds, but no refund.
I even wrote directly to the HLLY person on this very forum. No answer.
There is no possible way these amps are within the rated specifications.
I STRONGLY RECOMMEND YOU AVOID PURCHASING ANYTHING FROM THEM.
Mark
I bought not one, but two HLLY Tamp-90's. They are so NOISY with HISS that you cannot listen to them.
I've written at least a dozen letters to the company and the eBay vendor and just keep getting stalled.
Return shipping would be $209 -- cost prohibitive. I get promises of refunds, but no refund.
I even wrote directly to the HLLY person on this very forum. No answer.
There is no possible way these amps are within the rated specifications.
I STRONGLY RECOMMEND YOU AVOID PURCHASING ANYTHING FROM THEM.
Mark
S
spitzer
valleyman also problems with them but as seen in end of thread problem fixed by US sales department. Maybe they can take your return for cheaper.
http://www.diyaudio.com/forums/showthread.php?postid=1735491#post1735491
Why complaining when this for shopping? It just personal and we have to be good company for good deals. You did get what you paid for, good deals. IC d amps on ebay have noise expected but lots of cap tweak treads that help make sonic impact sweeter.
Hoping this help you and let us know because I have buying HLLY amp now for for good deal in active speaker big multi channel set up for boat races and barbecue.
http://www.diyaudio.com/forums/showthread.php?postid=1735491#post1735491
Why complaining when this for shopping? It just personal and we have to be good company for good deals. You did get what you paid for, good deals. IC d amps on ebay have noise expected but lots of cap tweak treads that help make sonic impact sweeter.
Hoping this help you and let us know because I have buying HLLY amp now for for good deal in active speaker big multi channel set up for boat races and barbecue.
One could easily believe that someone is not actually from the country the flag represents.
One could further believe that the same someone is not very comfortable with the use of english.
This could also lead one to believe that certain ebay vendors tries to shy away from responsibilities.
But who knows for certain what to believe
One could further believe that the same someone is not very comfortable with the use of english.
This could also lead one to believe that certain ebay vendors tries to shy away from responsibilities.
But who knows for certain what to believe
Maybe you are not used to complaints from dissatisfied customers where you are from - also maybe if not used to complaints from dissatisfied customers try to keep sales in country of origin, also maybe should take course in marketing with honest representation of product.
Ok, bud, the deal is: if you do not react to customers complaints, do not answer there request for rectification of the problem in a timely manner, do not be surprised when the name of company selling an unsatisfactory product gets muddied.
And make no mistake: in the western world the personal becomes public as a matter of course if you p/o people.
And another and: 200$ is enough money to expect a product working as a technologically product advanced enough to fulfill teh minimum requirements as to distortion, noise etc. , noisy crap you can buy for a lot less.
audiokraut...
my daughter's BF bought one of these. I haven't heard it, but he states it is noisy. Why would he lie? I've read elsewhere that some class D ( and class T ) amps have a significant amount of "hiss".
I don't know if this is THE solution, but would a filtered output work?
I do know that my 41 Hz amp makes no noise that is perceivable, and thus requires no such re-work.
I think one ought to take an "experimenter's approach" when you buy anything online that you are not familiar with.
Does this negate the seller's/designer's/company's obligation? I don't think so. Ultimately if enough people complain, it will have a profound effect on their sales.
Personally I think squeezing 90 watts/ch out of the 2020 is a big push...apparently the amp-20 has quite a bit of muscle and great sound to boot!
my daughter's BF bought one of these. I haven't heard it, but he states it is noisy. Why would he lie? I've read elsewhere that some class D ( and class T ) amps have a significant amount of "hiss".
I don't know if this is THE solution, but would a filtered output work?
I do know that my 41 Hz amp makes no noise that is perceivable, and thus requires no such re-work.
I think one ought to take an "experimenter's approach" when you buy anything online that you are not familiar with.
Does this negate the seller's/designer's/company's obligation? I don't think so. Ultimately if enough people complain, it will have a profound effect on their sales.
Personally I think squeezing 90 watts/ch out of the 2020 is a big push...apparently the amp-20 has quite a bit of muscle and great sound to boot!
The datasheet says 150uV output noise for the application circuit given, so there is probably something wrong with HLLY implementation.
I think that the problem is that people with enough knowledge to find a fix for the problem is not very likely to buy this amplifier to start with.
I would try to find a fix if someone is willing to donate a module to me and there are enough unsatisfied customers not receiving any reply from the seller and demanding a solution to justify the time expent in finding it.
I think that the problem is that people with enough knowledge to find a fix for the problem is not very likely to buy this amplifier to start with.
I would try to find a fix if someone is willing to donate a module to me and there are enough unsatisfied customers not receiving any reply from the seller and demanding a solution to justify the time expent in finding it.
Class D and Class T amplifiers are realy troublesome when is about PCB layout. this infuences the sound quality, noise and even the reliability of the amplifier.
one of the most important thing is to avoit ground loops and route the ground using star topology.
another one, is to keep the input paths as far as possible from the output.
output inductor makes the law. a coreless inductor will be an almost perfet RFI generator up to few MHZ. a bad placed inductor (close to the small signal paths, not necessary the inputs) will induce a lot of noise.
supply bypasing capacitors, which need to be mouted as close as possible to the ic pins, need to be both electrolytics and X7R SMD ceramics, with very low ESR and parasitic inductance.
also, most of the Tripath IC's has the sw freq. shifted with at least 25 KHz to supress most of the noise. to achieve that, the capacitors from the feedback loop need to be choosen with different values.
output filter, including output inductor and capacitor, can reduce the noise but not at all, by using a lower cut-off frequency, (33.6KHz requires 33uH + 0.68uF) or higher filter order (connect two or more filters in cascade).
as an advice, first thing to do before triyng to mod the amp. is to take a look at the pcb and see if one of the issues described above is there. if the layout is wrong, it will be really hard to fix-it.
one of the most important thing is to avoit ground loops and route the ground using star topology.
another one, is to keep the input paths as far as possible from the output.
output inductor makes the law. a coreless inductor will be an almost perfet RFI generator up to few MHZ. a bad placed inductor (close to the small signal paths, not necessary the inputs) will induce a lot of noise.
supply bypasing capacitors, which need to be mouted as close as possible to the ic pins, need to be both electrolytics and X7R SMD ceramics, with very low ESR and parasitic inductance.
also, most of the Tripath IC's has the sw freq. shifted with at least 25 KHz to supress most of the noise. to achieve that, the capacitors from the feedback loop need to be choosen with different values.
output filter, including output inductor and capacitor, can reduce the noise but not at all, by using a lower cut-off frequency, (33.6KHz requires 33uH + 0.68uF) or higher filter order (connect two or more filters in cascade).
as an advice, first thing to do before triyng to mod the amp. is to take a look at the pcb and see if one of the issues described above is there. if the layout is wrong, it will be really hard to fix-it.
cnx said:
Since the problem is "hiss" and because this amp has a volume control, the first thing I would do is check the gain of the amplifier. This is controlled by the resistors on the input-- Ri and Rf on the data sheet. It's possible they have simply set the gain fairly high so that the volume control would have more range. So there might be a very simple fix--just reduce the gain so the noise from the input stage doesn't get amplified as much, and use a low-noise op amp if that gain is needed.
Fix for HLLY Tamp-90
Hi Neil,
Can you give me some specifics on what you are thinking? I could even send you one of the amps if you want.
I do know of another fellow who has eliminated the volume pot and no change...still hissy.
He also tried a suggested mod from HLLY which was adding a 47pF cap across R7. Also no change.
So, I can tell you those things.
I am not well versed in electronics. That's why I bought this in the first place rather than build.
I was provided with no schematic for these amps.
Mark
Hi Neil,
Can you give me some specifics on what you are thinking? I could even send you one of the amps if you want.
I do know of another fellow who has eliminated the volume pot and no change...still hissy.
He also tried a suggested mod from HLLY which was adding a 47pF cap across R7. Also no change.
So, I can tell you those things.
I am not well versed in electronics. That's why I bought this in the first place rather than build.
I was provided with no schematic for these amps.
Mark
Re: Fix for HLLY Tamp-90
The Tripath reference circuit is designed to give a voltage gain of 18, which is a bit on the low side (1/2v signal on the input will only result in a 9V swing on the output). HLLY may have increased the gain to make the amp more versatile, and provided a volume control so that you can attentuate the input. However, any noise in the input circuit of the TA2022 will get amplified by the gain, so this MIGHT be the source of the hiss (although, as others have pointed out, there may be other causes).
The gain of the TA2022 is set by the resistors in the feedback loop for the input op amp and by the feedback for the modulator. If HLLY increased the gain, it is most likely that they did so by adjusting the feedback resistors on the input op amp--Rf and Ri on the attached schematic. You need to follow the traces from pins 23 (channel 1) and 26 (channel 2) and read the values on the tiny resistors that are connected to these pins. The input amp gain is simply Rf/Ri, and the reference design shows both resistors as 20K.
So get out your magnifying glasses and see if you can read the markings on these resistors.
Mark2727 said:
The Tripath reference circuit is designed to give a voltage gain of 18, which is a bit on the low side (1/2v signal on the input will only result in a 9V swing on the output). HLLY may have increased the gain to make the amp more versatile, and provided a volume control so that you can attentuate the input. However, any noise in the input circuit of the TA2022 will get amplified by the gain, so this MIGHT be the source of the hiss (although, as others have pointed out, there may be other causes).
The gain of the TA2022 is set by the resistors in the feedback loop for the input op amp and by the feedback for the modulator. If HLLY increased the gain, it is most likely that they did so by adjusting the feedback resistors on the input op amp--Rf and Ri on the attached schematic. You need to follow the traces from pins 23 (channel 1) and 26 (channel 2) and read the values on the tiny resistors that are connected to these pins. The input amp gain is simply Rf/Ri, and the reference design shows both resistors as 20K.
So get out your magnifying glasses and see if you can read the markings on these resistors.
Attachments
after some reading...
of the 32 page TA2022 product sheet from Tripath...
a couple of things jumped out at me. First Rf/Ri dominates the gain. in the previous image both are 20kΩ so gain is unity. To reduce the gain, a resistor change would be required. and a capacitor change as well (although if the change is small perhaps capacitor change may not be required?)
to calculate Ci:
Ci=1/(2*π* f *R)
where: R = Input resistor value in ohms.
f = Input low frequency pole (typically 10Hz or below).
Also Cfb1 and Cfb2 should be 390pF and 560pF respectfully (not the same value.. an apparent source of audible noise).
So I guess a place to start might be with Ri, and Rf, followed by Ci. And check for the values of Cfb1 and Cfb2.. after that ?????
stew
of the 32 page TA2022 product sheet from Tripath...
a couple of things jumped out at me. First Rf/Ri dominates the gain. in the previous image both are 20kΩ so gain is unity. To reduce the gain, a resistor change would be required. and a capacitor change as well (although if the change is small perhaps capacitor change may not be required?)
to calculate Ci:
Ci=1/(2*π* f *R)
where: R = Input resistor value in ohms.
f = Input low frequency pole (typically 10Hz or below).
Also Cfb1 and Cfb2 should be 390pF and 560pF respectfully (not the same value.. an apparent source of audible noise).
So I guess a place to start might be with Ri, and Rf, followed by Ci. And check for the values of Cfb1 and Cfb2.. after that ?????
stew
Also check on the forums at www.41hz.com
I think there was a big hiss problem with the same chip in one of the 41Hz amps.
Maybe there is a fix there. I suspect the bias cap or the +5V bus.
I think there was a big hiss problem with the same chip in one of the 41Hz amps.
Maybe there is a fix there. I suspect the bias cap or the +5V bus.
Long time lurker, first time poster...
I dislike it when sellers use the "pay postage to send it back and I'll sort it" line, knowing full well you live overseas and the cost is prohibitive.
A thought occurs... Hlly amps seem simple enough to take apart. Why not email the seller and tell him you are sending JUST the circuitboard back and you want a replacement?
I dislike it when sellers use the "pay postage to send it back and I'll sort it" line, knowing full well you live overseas and the cost is prohibitive.
A thought occurs... Hlly amps seem simple enough to take apart. Why not email the seller and tell him you are sending JUST the circuitboard back and you want a replacement?
i all,
i am the other that bought a hlly 2022 amp aong with mark2727, we sent each other numerous emails trying to fix the problem.
I did all the ******* cap add ons that they said for no result just a waste of time, i tried grounding certain areas with no result, even took the pot off and used it as a power amp for still the same bloody hiss. The only difference that had some result which was just an experiment was to make an l-pad before the speaker terminals, this reduced the damn hiss considerably.
Looked like they had too much gain for one thing and the board layout was probably not optimal, but these are just my uneducated guesses.
After weeks and weeks of emailing hlly with no success and getting vague responses and getting pissed off at them, i finally put in a dispute to paypal but i didn't want a refund and didn't want to pay to send the amp back because i wanted them to fix the problem for all rather than selling crap to the public.
What i fought for was for hlly to make a new bloody pcb and to reduce the gain. Well finally two days ago i received the version 2.2 pcb and hallelujia it is night and day the results. The hiss is all but obsolete and the sound comes in from a darker background now. So i am happy, just not so for having to do all this crap, but if it helps others well good.
So in essence, i would if anyone else has bought one or considering buying one of these is to make sure you gat the version 2.2 board inside as this is now a very good amp with it in. And the build quality is a plus.
Cheers all
i am the other that bought a hlly 2022 amp aong with mark2727, we sent each other numerous emails trying to fix the problem.
I did all the ******* cap add ons that they said for no result just a waste of time, i tried grounding certain areas with no result, even took the pot off and used it as a power amp for still the same bloody hiss. The only difference that had some result which was just an experiment was to make an l-pad before the speaker terminals, this reduced the damn hiss considerably.
Looked like they had too much gain for one thing and the board layout was probably not optimal, but these are just my uneducated guesses.
After weeks and weeks of emailing hlly with no success and getting vague responses and getting pissed off at them, i finally put in a dispute to paypal but i didn't want a refund and didn't want to pay to send the amp back because i wanted them to fix the problem for all rather than selling crap to the public.
What i fought for was for hlly to make a new bloody pcb and to reduce the gain. Well finally two days ago i received the version 2.2 pcb and hallelujia it is night and day the results. The hiss is all but obsolete and the sound comes in from a darker background now. So i am happy, just not so for having to do all this crap, but if it helps others well good.
So in essence, i would if anyone else has bought one or considering buying one of these is to make sure you gat the version 2.2 board inside as this is now a very good amp with it in. And the build quality is a plus.
Cheers all
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