Been Distracted with things not Audio
Hi Everyone,
Just checked the thread on the LME49710's for the first time in a month! Sorry!!! Been very busy working on a 1930's house in El Cerrito, that has been in the family since it was built, that I might have to sell just to survive this horrible job market.
Yes, again, the LM4562 and the LME49720 are identical parts however process variations can change things, like leakage, which appears to effect signal quality in some parts. I discovered this on the LME49811 project. We ended up screening out high leakage parts (for another reason unrelated to signal quality) and in my listening tests the rejected high leakage parts did not sound as good as the passed low leakage parts. This makes sense as leakage can have an effect on signal performance in unpredictable ways. However certain analog parts can still pass the production tests with some parts having higher leakage than others. This applies to all semiconductor companies. Reasons like this are why the Crown Select TDA1541 S1 DACS that Daredevil_KK is using in his D/A preamp existed over the regular TAD1541 DACS by using a screening test of some kind. By the way Daredevil_KK I still have a bunch of those old DAC’s if you need some. Mine are matched parts.
Secondly, we did a lot of single blind tests in the sound room with the Wilson Watt Puppies (model 7’s and I recently sent Dave Wilson an email asking if he needed an experienced audio engineer. No response.) Nearly 100% results that the metal can devices sounded better than the plastic DIP’s in my D/A preamp. Later with identical D/A preamps, using the AKM4396, we even compared the metal cans with the DIP’s in the custom power supply regulators we designed (with some help from Bob Pease who was also laid off!). Again nearly 100% results (with a small sample group) that the metal cans, in the 7 power supplies in my D/A preamp, were much better sounding than the DIPS in the same power supply circuits! I was actually shocked especially since a plastic LME49600 was in series with each metal can LME opamp! Even our resident “Tube Guy” (A National FAE who has his own tube equipment company) agreed that the metal cans were better than the dips in the signal path and power supplies. He even commented that I had acheived the smooth tube sound combined with the detail of solid state circuits! For the previous 5 years he had not liked the sound quality in the National sound room at all. I have a lot of thoughts as to why the metal cans make an audible difference even though they appear to measure the same on the AP2 and Bob P has some thoughts as well but since we are all gone from National now we don’t have the proper test equipment to get a good answer. Besides I am more worried about food money that audio right now since there are NO JOBS out there for audio engineers!
Sorry I was gone for so long and I promise to check in more often. Are there any other threads I need to look at?
Audioman54 / Mark
Hi Everyone,
Just checked the thread on the LME49710's for the first time in a month! Sorry!!! Been very busy working on a 1930's house in El Cerrito, that has been in the family since it was built, that I might have to sell just to survive this horrible job market.
Yes, again, the LM4562 and the LME49720 are identical parts however process variations can change things, like leakage, which appears to effect signal quality in some parts. I discovered this on the LME49811 project. We ended up screening out high leakage parts (for another reason unrelated to signal quality) and in my listening tests the rejected high leakage parts did not sound as good as the passed low leakage parts. This makes sense as leakage can have an effect on signal performance in unpredictable ways. However certain analog parts can still pass the production tests with some parts having higher leakage than others. This applies to all semiconductor companies. Reasons like this are why the Crown Select TDA1541 S1 DACS that Daredevil_KK is using in his D/A preamp existed over the regular TAD1541 DACS by using a screening test of some kind. By the way Daredevil_KK I still have a bunch of those old DAC’s if you need some. Mine are matched parts.
Secondly, we did a lot of single blind tests in the sound room with the Wilson Watt Puppies (model 7’s and I recently sent Dave Wilson an email asking if he needed an experienced audio engineer. No response.) Nearly 100% results that the metal can devices sounded better than the plastic DIP’s in my D/A preamp. Later with identical D/A preamps, using the AKM4396, we even compared the metal cans with the DIP’s in the custom power supply regulators we designed (with some help from Bob Pease who was also laid off!). Again nearly 100% results (with a small sample group) that the metal cans, in the 7 power supplies in my D/A preamp, were much better sounding than the DIPS in the same power supply circuits! I was actually shocked especially since a plastic LME49600 was in series with each metal can LME opamp! Even our resident “Tube Guy” (A National FAE who has his own tube equipment company) agreed that the metal cans were better than the dips in the signal path and power supplies. He even commented that I had acheived the smooth tube sound combined with the detail of solid state circuits! For the previous 5 years he had not liked the sound quality in the National sound room at all. I have a lot of thoughts as to why the metal cans make an audible difference even though they appear to measure the same on the AP2 and Bob P has some thoughts as well but since we are all gone from National now we don’t have the proper test equipment to get a good answer. Besides I am more worried about food money that audio right now since there are NO JOBS out there for audio engineers!
Sorry I was gone for so long and I promise to check in more often. Are there any other threads I need to look at?
Audioman54 / Mark
hello audioman54,
i can relate to you, i know the feeling, been there before, in 1988 there was a retrenchment and i joined it....was working for Advanced Micro Devices in the Philippines for almost 10 years, when recession hit......
that is why i have to go find a job in Russia, changed carreer path to the Oil and Gas refinery bussines.....
wish you the best of luck, hang in there!!!
i can relate to you, i know the feeling, been there before, in 1988 there was a retrenchment and i joined it....was working for Advanced Micro Devices in the Philippines for almost 10 years, when recession hit......
that is why i have to go find a job in Russia, changed carreer path to the Oil and Gas refinery bussines.....
wish you the best of luck, hang in there!!!
Re: Been Distracted with things not Audio
Just what would you be looking for in a test to see the effects of the metal can? I know the lead frame is constructed differently and the TO cans I have used were all using Kovar (magnetic) leads. There is an audiophile mantra that the magnetic leads are bad. I don't have a sample so I'm just guessing but I believe the cans have a glass or ceramic base the leads go through. This would be really a reach but the dielectric properties of the epoxy are different from the air and ceramic in the can. I have had similar experiences with dual jfets but never thought the can itself would be an issue. It may have been. There are lead spacers for the mechanically challenged that form a TO99 to a dip format. Jermyn made them Jermyn
audioman54 said:
Just what would you be looking for in a test to see the effects of the metal can? I know the lead frame is constructed differently and the TO cans I have used were all using Kovar (magnetic) leads. There is an audiophile mantra that the magnetic leads are bad. I don't have a sample so I'm just guessing but I believe the cans have a glass or ceramic base the leads go through. This would be really a reach but the dielectric properties of the epoxy are different from the air and ceramic in the can. I have had similar experiences with dual jfets but never thought the can itself would be an issue. It may have been. There are lead spacers for the mechanically challenged that form a TO99 to a dip format. Jermyn made them Jermyn
Re: Re: Been Distracted with things not Audio
I will add my 2 cents. The leads on the 49710 are magnetic, they snap firmly to a neo magnet.
In my discussions with audioman54, we did not focus on metal can effects; rather we hypothesized that there may be something detrimental about the epoxy dip package (such as thermal stresses). Whatever it is, it does not show up in the metal can package.
1audio said:
I will add my 2 cents. The leads on the 49710 are magnetic, they snap firmly to a neo magnet.
In my discussions with audioman54, we did not focus on metal can effects; rather we hypothesized that there may be something detrimental about the epoxy dip package (such as thermal stresses). Whatever it is, it does not show up in the metal can package.
Re: Been Distracted with things not Audio
Any help with this would be greatly appreciated:
LME49830 on higher rails than output devices?
audioman54 said:
Any help with this would be greatly appreciated:
LME49830 on higher rails than output devices?
Mark,
You have mentioned IC "leakage" several times. What sort of leakage are you referring to? If I were to measure National or brands A, T or B for such leakage, what sort of circuit and methodology would I use? I've done op-amp testing before and have seen many 'leakages', but which ones in specific?
thanks
You have mentioned IC "leakage" several times. What sort of leakage are you referring to? If I were to measure National or brands A, T or B for such leakage, what sort of circuit and methodology would I use? I've done op-amp testing before and have seen many 'leakages', but which ones in specific?
thanks
Hi Brian L,
The guys who do the production testing told me about the leakage tests and I did not ask them how they did it. All I cared about was that the parts with lower leakage performed better in my listening tests. I wanted to do more testing with my AP2 192 cascade (wish I had one at home now! Anyone have a used one for sale...cheap!) on the various lots of passed and failed parts but did not get to it before I was laid off. I do know that it is tested by reverse biasing a diode on the die and measuring the leakage current. I will ask Bob Pease to give me a better description of a current leakage test and report back later.
Also Rocket Scientist I was just talking with benchtester about your question (higher voltage on the LME49810/811/830/4702 than on the output stage) which we have talked about in the past but again I never got time to try it! Why don't you hook it up and let us know what happens? (I know it would have been easier for us to do it at National with free parts!) I will also ask Bob P about this. Maybe SpittinLama has some thoughts on this issue as well?
Mark / Audioman54
The guys who do the production testing told me about the leakage tests and I did not ask them how they did it. All I cared about was that the parts with lower leakage performed better in my listening tests. I wanted to do more testing with my AP2 192 cascade (wish I had one at home now! Anyone have a used one for sale...cheap!) on the various lots of passed and failed parts but did not get to it before I was laid off. I do know that it is tested by reverse biasing a diode on the die and measuring the leakage current. I will ask Bob Pease to give me a better description of a current leakage test and report back later.
Also Rocket Scientist I was just talking with benchtester about your question (higher voltage on the LME49810/811/830/4702 than on the output stage) which we have talked about in the past but again I never got time to try it! Why don't you hook it up and let us know what happens? (I know it would have been easier for us to do it at National with free parts!) I will also ask Bob P about this. Maybe SpittinLama has some thoughts on this issue as well?
Mark / Audioman54
Dear Mark!
I had built the amplifier with LME49811 with Sanken SAP15s darlington folow Jackini' schema
http://www.diyaudio.com/forums/showthread.php?s=&threadid=143263&highlight=lme49811
Sound is excellent, but I think it need a buffer or low gain preamp for max power.
Can you help me for a good schema, example is LME49813' schema?
Thanks.
I had built the amplifier with LME49811 with Sanken SAP15s darlington folow Jackini' schema
http://www.diyaudio.com/forums/showthread.php?s=&threadid=143263&highlight=lme49811
Sound is excellent, but I think it need a buffer or low gain preamp for max power.
Can you help me for a good schema, example is LME49813' schema?
Thanks.
audioman54 said:
Thanks for the answer Mark. If you find out anything from the guys above, please let me know? SpittinLama hasn't posted here for a few months last time I looked. If I don't hear from anything negative I'll try my luck with the multiple rails and see what happens. I've sent off my gerbers and am waiting for PCBs....
Also, as it's in your backyard, do you plan to attend Burning Amp this fall? It would be great to see you there!
Hi Rocket Scientist,
Benchtester went last year (to burning amp) and he wants me to go with him this year. He took my D/A last year and I have a few improvements in the new one. Hopefully I can get the new AKM4399 into one of my 4396 D/A preamps along with some power supply changes Bob Pease and I talked about at the last AES in SF.
And Minhtriet,
I am glad you like your 49811 amplifier. It is what I use in my sound room at home.
Best Regards Everyone,
Mark / Audioman54
Benchtester went last year (to burning amp) and he wants me to go with him this year. He took my D/A last year and I have a few improvements in the new one. Hopefully I can get the new AKM4399 into one of my 4396 D/A preamps along with some power supply changes Bob Pease and I talked about at the last AES in SF.
And Minhtriet,
I am glad you like your 49811 amplifier. It is what I use in my sound room at home.
Best Regards Everyone,
Mark / Audioman54
Thanks Mark,
for your offer, but do not need any more TDA1541 and how did you know that I was using the crown version? But I do need your expertise.
Does the LME49720 perform better as a unity gain buffer or as a gain buffer and what range of values for the feedback and grounding resistor is the most suitable (1k to 10k? More? Less?)
Lastly, my TDA1541 will be connected to a I/V resistor and then to a output transformer (1:6). Do I need a buffer after the transformer, since I have a buffer after attenuator?
Cheers,
KK
for your offer, but do not need any more TDA1541 and how did you know that I was using the crown version?
But I do need your expertise.Does the LME49720 perform better as a unity gain buffer or as a gain buffer and what range of values for the feedback and grounding resistor is the most suitable (1k to 10k? More? Less?)
Lastly, my TDA1541 will be connected to a I/V resistor and then to a output transformer (1:6). Do I need a buffer after the transformer, since I have a buffer after attenuator?
Cheers,
KK
Hi KK,
The crown select is the only chip worth using in the TDA1541 series, that is how I knew!
Also "coupling transformer"? I would NEVER EVER put a transformer in my signal path if I could avoid it.
Use the LMe49710/20 in inverting mode with the lowest value reisitors you can tolerate to get the gain you need. AND no coupling/DC blocking caps or transformers in the signal path!
I have to say that the new AKM Dacs blow away those old 1541's. That is why I sold almost all of my TDA1541S1 crown chips that I used in the the "MSB Technology stuff" I built 20 years ago!
I still have some matched, same #'s, crown select chips left if anyone wants to buy them though!? Since I just heard today that Monster Cable does not think I am "director level" material and on Friday Apple told me I was over qualified I could use some "house payment" money this month! No jobs for 55 year old analog audio engineers or even technicians out there right now!
Best Regards,
Mark / Audioman54
The crown select is the only chip worth using in the TDA1541 series, that is how I knew!
Also "coupling transformer"? I would NEVER EVER put a transformer in my signal path if I could avoid it.
Use the LMe49710/20 in inverting mode with the lowest value reisitors you can tolerate to get the gain you need. AND no coupling/DC blocking caps or transformers in the signal path!
I have to say that the new AKM Dacs blow away those old 1541's. That is why I sold almost all of my TDA1541S1 crown chips that I used in the the "MSB Technology stuff" I built 20 years ago!
I still have some matched, same #'s, crown select chips left if anyone wants to buy them though!? Since I just heard today that Monster Cable does not think I am "director level" material and on Friday Apple told me I was over qualified I could use some "house payment" money this month! No jobs for 55 year old analog audio engineers or even technicians out there right now!
Best Regards,
Mark / Audioman54
Hi Panson,
How is business in the HK? I heard it is worse than here?
I have been letting it be known that I am available for contract work but nothing has come in yet. Problem is the economy is so bad right now companies and individuals are holding on to their money waiting for things to pick and until someone makes the first move (other than the government!) we are going to be in limbo for awhile...and that means I am retired. Good news for the forum here though because it means I have more time to answer your LME questions.
Now if you could all flood National Semi Audio with emails asking them why they got rid of Silicon Valley legend Bob Pease and Audio Guru (please pardon the pat on my own back) Mark Brasfield maybe I could go back and finish the LME product line. Unlikely though as now they are the "Power Wise" (that is the actual catch phrase) and Solar Panel Controller Company! But as long as we all keep using the LME parts (and hopefully get a big company to use them) they will be around a long time! And that was worth the last 10 years I spent there!!!
Is everyone out there happy with the 0.00005%THD+N series of LME parts that include the LME49710 VFB opamp or LME49713 CFB opamp or LME49811 +/-100VDC power amp preamp or LME49600 buffer or ... I like to think these parts are a nice legacy for all of us "audio crazies" that are gone from NSM now... and remember the HA metal cans are the best way to go!
Mark / audioman54
How is business in the HK? I heard it is worse than here?
I have been letting it be known that I am available for contract work but nothing has come in yet. Problem is the economy is so bad right now companies and individuals are holding on to their money waiting for things to pick and until someone makes the first move (other than the government!) we are going to be in limbo for awhile...and that means I am retired. Good news for the forum here though because it means I have more time to answer your LME questions.
Now if you could all flood National Semi Audio with emails asking them why they got rid of Silicon Valley legend Bob Pease and Audio Guru (please pardon the pat on my own back) Mark Brasfield maybe I could go back and finish the LME product line. Unlikely though as now they are the "Power Wise" (that is the actual catch phrase) and Solar Panel Controller Company! But as long as we all keep using the LME parts (and hopefully get a big company to use them) they will be around a long time! And that was worth the last 10 years I spent there!!!
Is everyone out there happy with the 0.00005%THD+N series of LME parts that include the LME49710 VFB opamp or LME49713 CFB opamp or LME49811 +/-100VDC power amp preamp or LME49600 buffer or ... I like to think these parts are a nice legacy for all of us "audio crazies" that are gone from NSM now... and remember the HA metal cans are the best way to go!
Mark / audioman54
audioman54 said:
Happy with them? I am ecstatic! I will be using them in my own preamp design, until something better comes along, which is difficult to imagine at this point.
I'm glad to know I wasn't going crazy when the LME49720HA sounded better to me in my preamp than the LME49720NA. It seem to me that it is a combination of more mass, and better shielding. It definitely seems to pick up less "crap" from the external world, which is a major bonus since my preamp design runs on lead/acid gelpack batteries.
I hope you find a new home worthy of your talents! I've been "retired" and/or "self-employed" the last three years now. If I didn't know how to work on tube gear, I'd probably be living under a bridge by now!
BT
audioman54 said:
Stock and property markets are pretty good. The Hangseng index keeps going up. Rich people are looking for investment opportunities in these area. However, job market is still not good at all. Mainland China is likely the driving force for recovery.
I like your situation - unemployed. Luckily I purchased useful equipments when employed. I get some income from freelance jobs and selling LME498xx boards. More important, my wife is very supportive! She is now the source of income!
Benchtester and I are working on a complete LME based system with triamped speakers (run with my LME49811 power amps) and the first prototypes Benchtester built with just internal passive crossovers sounded better than the Watt Puppies at National with all my stuff. The active analog or digital crossovers will be even better! Maybe we can make a business selling the complete system to some well off audiophiles here in the USA!
Benchtester is a Mech wizard and has his own mill! He is machining the boxes for the speakers!
I need to spend less time on line job hunting every day (9 months thus far at about 6 hours a day) and more time finishing up all the equipment. I have not put the new AK4399 into my AK4396 all LME based D/A preamp yet. My buddies at AKM gave me a demo board (they use the LME parts on their demo boards by the way!) and I have not had time to shoehorn it into my preamp to see if there is any improvement over the 4396. 24 bits vs 32 bits? I do not know if that is audible with 16 bit source material.
Thanks everyone for the kind words and support you are giving me. It really does pick me up and keep me going!!!
Mark / Audioman54
Brass Teacher save me a spot under that bridge in case I don't find something soon! My wife is talking about me selling my favorite toy I bought with National stock (GT500 SVT#12) but I have a ways to go before I sink that low!!! In fact I think I would rather sell the house and keep the car!
Benchtester is a Mech wizard and has his own mill! He is machining the boxes for the speakers!
I need to spend less time on line job hunting every day (9 months thus far at about 6 hours a day) and more time finishing up all the equipment. I have not put the new AK4399 into my AK4396 all LME based D/A preamp yet. My buddies at AKM gave me a demo board (they use the LME parts on their demo boards by the way!) and I have not had time to shoehorn it into my preamp to see if there is any improvement over the 4396. 24 bits vs 32 bits? I do not know if that is audible with 16 bit source material.
Thanks everyone for the kind words and support you are giving me. It really does pick me up and keep me going!!!
Mark / Audioman54
Brass Teacher save me a spot under that bridge in case I don't find something soon! My wife is talking about me selling my favorite toy I bought with National stock (GT500 SVT#12) but I have a ways to go before I sink that low!!! In fact I think I would rather sell the house and keep the car!
audioman54 said:
Thanks Mark,
But what is the reason why inverting is better then a non? And how low can the resistor be with out straining the opamp? In the hundreds or tens range?
Lastly, good I/V circuit for the TDA1541S1 that you would recommend building?
Wow AKM blowing away TDA1541S1, must try them out too.
KK
audioman54 said:
Yeah Mark I hope you're don't have to sell the GT500! Just tell your wife this probably isn't the best time to sell it anyway. I just read an article how even Ferrari dearlers are having to resort to deep discounts to move some of their inventory in this economy.
And, thanks again for all your great contributions here. I think the collection of serious talent and knowledge on this forum is impressive. And, IMHO, you're right up there with the likes of Bob Cordell, John Curl, Douglas Self, Nelson Pass and other the "industry celebrities" who generously contribute their time here.
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