..coil change?
According to doctor´s list i made a buy list...at the dimesnion i try to set the colors like a traffic light...
red is too big
yellow could be ok
green fits
but be aware of the "technical color" of doctors tests....
chris
According to doctor´s list i made a buy list...at the dimesnion i try to set the colors like a traffic light...
red is too big
yellow could be ok
green fits
but be aware of the "technical color" of doctors tests....
chris
Hi please note LME49860 is available in DIP8, I tried it in the fx502spro. IMO it does not sound as good as 49720
This picture from the TPA3250 user guide shows a small value capacitor (C18) in the feedback loop. The capacitor is there to improve stability for all type of OP-amps and especially for high bandwidth amps like the 49720.
It could be present in the FX502S but haven't checked. That said, I didn't had any problems with LME49720.
I know that some users have complained of the amp overheating under normal operation and it is probably from high frequency oscillation. This capacitor is one way to lessen this problem. But if you don't have any problem, there is no need to panic.
Attachments
Thanks Strongbow60 for your quick response !
Yes i am happy...but i want to know if some other opamp is inplemented.
thx
chris
the HS does get warm-- i recommend running amp with lid off, I run it with lid raised up a few mm with some small plastic pieces wedged between the top and bottom chassis. i have not had any error light however, or overheat. could just be a poorly mounted heatsink? be sure to run at 24v only...I tried some other voltages (20-30v) and immediately noticed more heat (and reduced sound quality). My tpa3118 wiener board was optimal at 18-19v, i think there is a sweet spot for supply voltage for these amps, maybe someone with more EE knowledge can explain this.
Ran 32hz test tone thru my BMR speakers on this amp. The linear lab powersupply showed almost 1Ax24V=24W which is the highest ive ever seen it. I didnt play it long like this since this was like 2x the power ive ever seen it at even in high load. But no red LED, no overheating... Maybe my sample is just lucky good one...also didnt blow out my brand new expensive speakers which is good
Hi
If you read on the psu 24W that means the power consumption of the complete amp. this is not the power per channel
your speakers are 80db/W ?power consumption is at idle mode…..at 24V is 20mA = 500mW
if amp is switched on power consuption is at 24V 160mA = 3,8 WATT
so with an efficiency of about 85 -90%, and the amps needs 4w and splitt into 2 channels its less power.
24-4 = 20W--> 20W*0.85 = 17W --> splitt in 2 channles = 8,5Watt.
please look at some (a lot of...)pages before. i did a lot of investigation to mod this amp to get a better working amp with better SQ.
chris
Better SQ is verified only by ear?
yes it cost me a lot of effort to do so. as you can read lot of pages before i try to review all technical changes to its results.
i did a blind test with a different listener ,different speakers in a different room. so my changes are "proved"
So noone of the listeners did know that something "must" be different?
no
just ask the question: is there a difference or not?
That said, everyone involved was on the bias of listening to absolutely stock amplifiers with identical components
partly
i compare the modded but identical fx502Spro with just the diferent opamp on DISCO M (the red is better) and other bigger (complex) speakers.
Die DISCO M - ein hochstwertiger Kompaktlautsprecher | felbi.at | Website von Thorsten Felbinger
how do you handle your compare session?
OT:
I don't rely on listening tests, as they somehow fail at a certain point due to biasing.
When i ask somebody for a listening, i don't tell what to expect or what to listen to. I just ask, if they "think" theres something different and what. They point is, that mostly there's something different even if you don't change anything. -> so having the same device listened twice or more often. This is also valid for food and drinks.
If you tell people about a difference, they will hear/smell/taste a different, even with the same test source.
Asking someone who is not into audio/listening for hearing a difference in opamp implementation works only for implemenations where the passive circuit is totally maladjusted for the DUT.
To sum up, the listening experience is also a function of mood, daytime, air-pressure, humidity, age and "deafness".
I mostly rely on measurements and plots to provide a solution which is "neutral". Of course, a super specified amp may not "sound" pleasant, but this belongs to the personal listening habit.
(While speakers (can) change their frequency response with time, like "burn-in" which can be measured and easily be seen, i haven't seen/measured this effect on an amplifier.)
I don't rely on listening tests, as they somehow fail at a certain point due to biasing.
When i ask somebody for a listening, i don't tell what to expect or what to listen to. I just ask, if they "think" theres something different and what. They point is, that mostly there's something different even if you don't change anything. -> so having the same device listened twice or more often. This is also valid for food and drinks.
If you tell people about a difference, they will hear/smell/taste a different, even with the same test source.
Asking someone who is not into audio/listening for hearing a difference in opamp implementation works only for implemenations where the passive circuit is totally maladjusted for the DUT.
To sum up, the listening experience is also a function of mood, daytime, air-pressure, humidity, age and "deafness".
I mostly rely on measurements and plots to provide a solution which is "neutral". Of course, a super specified amp may not "sound" pleasant, but this belongs to the personal listening habit.
(While speakers (can) change their frequency response with time, like "burn-in" which can be measured and easily be seen, i haven't seen/measured this effect on an amplifier.)
Hi
If you read on the psu 24W that means the power consumption of the complete amp. this is not the power per channel
power consumption is at idle mode…..at 24V is 20mA = 500mW
if amp is switched on power consuption is at 24V 160mA = 3,8 WATT
so with an efficiency of about 85 -90%, and the amps needs 4w and splitt into 2 channels its less power.
24-4 = 20W--> 20W*0.85 = 17W --> splitt in 2 channles = 8,5Watt.
please look at some (a lot of...)pages before. i did a lot of investigation to mod this amp to get a better working amp with better SQ.
chris
Yes those measurements are the same as on my amp, both in "idle/off" and on mode. My speakers are rated at -85db however they are by Dennis Murphy who tends to be a little more realistic/honest with his ratings. My ascend CBM-170SE rated for supposedly -89db actually come out to about the same sensitivity (to my ear) as my philharmonic BMR rated for -85db, and the BMR is a 3-way compared to the ascend 2-way.
I did mod my amp with the LME49720, as well as using linear lab variable power supply, aside from that havent touched anything. My hand is not so steady so I prefer not to be soldering anything, and messing with SMD components is out of the question for me as well. I will check out your mod recommendations but it seems to be the opinion of people on here whos knowledge is have a lot of respect for that there is not much more to be done to this amp to get it to sound much better, but maybe I will buy a spare v5 at some point so i can mod this one.
And yes I agree with doctormod above 100% that perceived sound quality very much varies with humidity, mood, temp, etc, but the difference I have noticed will be more easily perceptible with better speakers/amp/setup
Hi Jigglebones
thanks for your answer. Do you use the lab psu with 28V?
Yes i agree to doctormords statement too. its the complete system: Source - amp and speakers to be a good or a very good SQ.
the last years I had 5 different DAC (mutec MC3+RME, mytec brooklyn, Devialet 170, Marants NaS1, Aune S16, -->Gustard A20H)and actually still 4 different (commercial: Arcam AVR390, Denon 1804 biamping, Hifi akademie P6 (brother), Accuphase P300V) amps + 5 Class D boards (2 x fx502spro, 2x YJ TPA3255 + TI 3251EVM) + a DIY PASS F5 by my brother.....to make cross checks.
the last 30 year my friends and myself we do not care about "religion" or class - just compare what sounds best. E.g Linn preamp on Accuphase power amp..+T+A Pre and Poweramp...vice versa...etcs
for modding I can give you the hint to try it...its not so difficult as it looks like.
chris
thanks for your answer. Do you use the lab psu with 28V?
Yes i agree to doctormords statement too. its the complete system: Source - amp and speakers to be a good or a very good SQ.
the last years I had 5 different DAC (mutec MC3+RME, mytec brooklyn, Devialet 170, Marants NaS1, Aune S16, -->Gustard A20H)and actually still 4 different (commercial: Arcam AVR390, Denon 1804 biamping, Hifi akademie P6 (brother), Accuphase P300V) amps + 5 Class D boards (2 x fx502spro, 2x YJ TPA3255 + TI 3251EVM) + a DIY PASS F5 by my brother.....to make cross checks.
the last 30 year my friends and myself we do not care about "religion" or class - just compare what sounds best. E.g Linn preamp on Accuphase power amp..+T+A Pre and Poweramp...vice versa...etcs
for modding I can give you the hint to try it...its not so difficult as it looks like.
chris
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Hi Jigglebones
thanks for your answer. Do you use the lab psu with 28V?
Yes i agree to doctormords statement too. its the complete system: Source - amp and speakers to be a good or a very good SQ.
the last years I had 5 different DAC (mutec MC3+RME, mytec brooklyn, Devialet 170, Marants NaS1, Aune S16, -->Gustard A20H)and actually still 4 different (commercial: Arcam AVR390, Denon 1804 biamping, Hifi akademie P6 (brother), Accuphase P300V) amps + 5 Class D boards (2 x fx502spro, 2x YJ TPA3255 + TI 3251EVM) + a DIY PASS F5 by my brother.....to make cross checks.
the last 30 year my friends and myself we do not care about "religion" or class - just compare what sounds best. E.g Linn preamp on Accuphase power amp..+T+A Pre and Poweramp...vice versa...etcs
for modding I can give you the hint to try it...its not so difficult as it looks like.
chris
I have tried various voltages from 20-30V and found the amp does not like anything other than 24V-- any deviation from 24V results in worse sound (to my ears) and increased heat production. I have plenty of output at 24V however and I am happy with it-- even very bass heavy electronic music or movies give no problems and sound clean. My TPA3118 amp (Wiener stereo board) preferred 18-19V for comparison. My concern with modding is that my speakers are somewhat expensive (~1400usd) and I do not want to be too risky and damage them, but I do have a cheaper pair for testing. If there is any very easy/cheap mods that you think give a good improvement I am willing to listen! If I need to spend 120$ on input transformers however maybe not
My source is a JDSLabs OL DAC, I have been very happy with it so far, and it was a good improvement over my previous JDSLabs ODAC rev.A
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for modding I can give you the hint to try it...its not so difficult as it looks like.
chris
It would be good to give all the changes, step by step with explanations and pictures in one post.
It would be good to give all the changes, step by step with explanations and pictures in one post.
Step 1:
if you want to use the 24V original PSu (or later a stronger with 24Vdc) then you have to do the first step:
change the LM317 configuration.
page 52-53..#521 its the final.
otherwise the psu must exeed 27 to 28V to let the LM317 work correctly.
Step 1:
if you want to use the 24V original PSu (or later a stronger with 24Vdc) then you have to do the first step:
change the LM317 configuration.
page 52-53..#521 its the final.
otherwise the psu must exeed 27 to 28V to let the LM317 work correctly.
I tried again setting my PSU to 28V and compare to 24V.....and I do prefer the 24V, sounds better and cleaner less offensive to my ear. The PSU is pretty well regulated however.