I thought that was obvious from context. I hate it when in any post I have to go back to the absolute basics, Andrew.
Jan
I have a few questions regarding to SE VAS with CCS on one side.
1) Is the simple SE IPS without cascode, SE VAS with CCS tail called "Blameless amp"?
2) I read 3 or 4 schematics of Nelson Pass specifically Threshold amps, they are all SE VAS with CCS. They are SE IPS with cascode. This is Threshold!!!! by Nelson Pass!!!! These are high end stuffs well respected in audiophile world. You even have a section for Pass!!!! Are you guys telling me they are inferior?
I am not trying to offend anyone as I am only 4 months into audiophile and less than 2 months really studying SS amp. I hate to sound skeptical, does all the bells and whistles translate to better sound? Or are these exercise of "just because I can !!!"? Hypes never work on me, big name brands and commercial never work on me. I absolutely can hear the difference of different brands of amp, not just by the names.
My all time favorite amp YBA has a very simple circuit design also. I never even heard of YBA before I listened to it. I was not even shopping for amp at the time as I just got my Acurus. I was buying my pair of JMLab 931 and I brought my Acurus to listen to the speaker. I was stunned, absolutely stunned how much better was the YBA. I learn the name from that!! YBA has very simple schematic, nothing like all the current mirror load etal. YBA is the reason I am even here. At the same time, I never like Mechantosh that have really complicated schematics.
1) Is the simple SE IPS without cascode, SE VAS with CCS tail called "Blameless amp"?
2) I read 3 or 4 schematics of Nelson Pass specifically Threshold amps, they are all SE VAS with CCS. They are SE IPS with cascode. This is Threshold!!!! by Nelson Pass!!!! These are high end stuffs well respected in audiophile world. You even have a section for Pass!!!! Are you guys telling me they are inferior?
I am not trying to offend anyone as I am only 4 months into audiophile and less than 2 months really studying SS amp. I hate to sound skeptical, does all the bells and whistles translate to better sound? Or are these exercise of "just because I can !!!"? Hypes never work on me, big name brands and commercial never work on me. I absolutely can hear the difference of different brands of amp, not just by the names.
My all time favorite amp YBA has a very simple circuit design also. I never even heard of YBA before I listened to it. I was not even shopping for amp at the time as I just got my Acurus. I was buying my pair of JMLab 931 and I brought my Acurus to listen to the speaker. I was stunned, absolutely stunned how much better was the YBA. I learn the name from that!! YBA has very simple schematic, nothing like all the current mirror load etal. YBA is the reason I am even here. At the same time, I never like Mechantosh that have really complicated schematics.
Last edited:
Most push-pull VAS are pure Class A and can deliver +/- their standing current.
AndrewT's comments are appropriate for SE VAS.
You need to use a diode connect PNP or NPN from LTspice's library.
These are amazing devices for other stuff as well. But I haven't been able to find them at Mouser or Digikey
Recommendations for sources please.Alan, SE VAS with CCS load goes back to AT LEAST Jack Sondermeyer of RCA in the early 70's.
"Blameless" is just a convenient name for Self's fave topology as described in his books and articles.
Got a circuit and link for your YBA amps?
If you define 'general use' as 8R & 4R loads, Blameless is without doubt the simplest topology for low THD .. especially if you use somewhat cleverer compensation like Pure Cherry.
But I'm really a speaker designer and like amps to cope with the EVIL loads I dream up.
Your Fig 6.16 (4th edition) has problems with 2R & 3R loads even when not overloaded. I don't expect an inexpensive 2x50W domestic amp to give its full spec into 2R but I object to oscillation on part of the cycle and yucky overload & recovery on even EVIL loads.
Of course if the design brief was for 2R loads, I'm sure a good dedicated Blameless could be dreamt up.
___________________________
I asked if you'd done further 'real life' work on Fig 5.39 & 5.40 (4th ed), the variation of THD with level of EF2 and CFP output stages.
Is there new stuff in your latest edition on this important but little known subject?
I don't have the Self's book. I just search here and all the blameless amp are what I described.
I can't find any link, attached is what I have, I believe it's "Passion" something. I saw some others but the topology is pretty much the same......Complementary LTP with only resistor load. No beta enhancement VAS, no 3EF. Particularly, I was wrong, it does not even have cascode for the LTP pairs!!!
I can tell you, the YBA that stunned me was only a small 70W amp. The size is small and the looks absolutely did not stand out. It looked so ordinary. It was in the showroom for a while and was used to test all the speakers. I never even ask question, mainly concentrated on the speakers. It was the day when I want to purchase the speaker, I brought my Acurus in to test the speaker. My Acurus is not a dog by any means, it's over $1000 in 1998. But the difference was stunning. I kept kicking myself since. That YBA was closed out for over $3000!!!! I would have bought it if my Acurus was not only a month old!!!
I bought the Acurus when I had the pair of Kef floor standing speakers. The Acurus matched them well. I tested a few amps in my days including Mchantosh, Bryston, one Krell, Adcom and a few others that I don't remember. The only two that turn head for me were YBA and a SE Cary. These two were head and shoulder above the others. I don't even know how to describe the sound other than to say it comes alive. They actually have kind of 3 dimension, echoey. They sounded like you were in a concert hall, a little airy like Martin Logan type static speaker. I listened to my friend's system with Threshold Class A driving a pair of Martin Logan, that was impressive also. I brought my own CD for testing to have consistency.
I really don't know how to relate distortion to the sound, since everyone talk distortion, so I can only follow along. But ultimately, the hell with the distortion spec, I just want the sound!!!! I particularly don't like Mchantosh as it sound dead to me. Most amps sounded "clinical", few comes alive to me.
Looking at the well respected Threshold and Pass Lab and YBA, I really start questioning whether I should throw away the books and go back to the basics!!!!
Attachments
Last edited:
Schematic like that, should have high distortion. I think you like colorfull sound (high distortion). Then you should design an amplifier with sound effect built in
Threshold and some other designs from Nelson Pass are just as primitive, single ended IPS, no beta enhancement VAS, asymmetrical VAS with CCS on one side. He even came out as said he use high emitter resistance for power transistors that violates the Oliver's optimization. Anyone dare to argue with Mr. Pass and his Threshold?Schematic like that, should have high distortion. I think you like colorfull sound (high distortion). Then you should design an amplifier with sound effect built in
Are we analyzing circuit or are we listening? It's like reading a poem, are you looking for grammar or are you looking for the emotion? Not to mention the biggest source of distortion of the system is the speaker, amp does not even come close.
Last edited:
I made an amplifier and I measure the THD is 0,06% at 1kHz, 120W, 8,2Ohm. And I still know the different of it sound compare with other amplifier
If you like high distortion, no problem. It is your taste. But I like an accurate sound whatever it sound pleasant or not.
What is accurate sound? There is so much distortion in the recording process and reproduce from the speakers. I played in the band for years, audiophile can never produce the sound of a real instrument or voice......nor do you even want that. If you listen to live violin, drums, sax and even human voice, they are harsh, scratchy. If a system truly reproduce that real sound, I don't think you'd want that. That's the reason people can tell whether it's recorded music or live music from far away, you can never reproduce the real sound. It's so glaringly different.I made an amplifier and I measure the THD is 0,06% at 1kHz, 120W, 8,2Ohm. And I still know the different of it sound compare with other amplifier
If you like high distortion, no problem. It is your taste. But I like an accurate sound whatever it sound pleasant or not.
Of course there is no accurate sound, but we can produce almost accurate sound
That why Mr. Cordell wrote a book to explain how to achieve it. If you want an amplifier with high distortion, please do not read his book Pleasant sound is subjective. Most of people in my country want high SPL especially at low frequency. They do not care if an amplifier have 23% THD at 20kHz or have 0,5V/uS slew rate. Can they call audiophile too?
Last edited:
Morning to you all. please I need your helps on How to build my own power amplifier, as I don't have a schematic for now. in my local area here I have access to transistors like 2n5551, 2n5401, a1013, tip41, 42, 2sc5200, 2sa1943 then lots of resistors. please is there any good schematic I can get for the available materials I have in hand? I want to build a power amp that is up to 500Watt and above at 8ohms. thank you all, I will be expecting your professional replies.
I have not heard anything comes close. Of cause I never listen to $100K+ system. The most expensive speaker I listened to was Wilson and JMLab that are over $10K a pair in 1998. No they are not. I don't know of any mic can pick up real sound. I played with a little recording, I yet to even get the guitar sound right.Not true. It can be reproduced, but not trivial to do so - reproduced sound when done correctly is very intense, just like the real thing - many people probably wouldn't feel comfortable with that, and may request diluting of the experience ... horses for courses,
Anyway, I don't want to side track Mr. Cordell's thread. Let's get back to the electronics. For $42 a run of 10 of 3"X2", I might do a few runs of IPS/VAS of different topologies. Then I can compare with my own ears.
Last edited:
If you want to design an amplifier, you should define an ideal amplifier first. And then try to make an amplifier as close as possible to the ideal amplifier. If you do not know an ideal amplifier, then you can not judge a real amplifier.
My ideal amplifier was changed when my knowledge improve... I want make every amplifier topology if I can. Just to know how it sound and how can I improve it... It is all about DIY
My ideal amplifier was changed when my knowledge improve... I want make every amplifier topology if I can. Just to know how it sound and how can I improve it... It is all about DIY
engrlvtn, I have moved your other post to a new thread where you should pick up more answers and general help.
http://www.diyaudio.com/forums/solid-state/269330-help-first-amplifier-design.html
Really? I don't think that is the case. A push-pull circuit can deliver much more current than the standing current. Witness the millions of class AB amplifiers routine delivering many amps from a standing current of 50mA.
Not wanting to speak for Douglas but this is a common misconception from people who haven't read the original articles. 'Blameless' means an amplifier where all the usual distortion types (I believe Doug's last count stands at 8 or 9 types) have been minimized as far as practical. It does not specify a specific topology.
Jan
I read his article on Distortion of Power amp. The topology is SE IPS with asymmetrical VAS. I did a search through this site, every schematic I saw in the threads is like that. I don't have D Self's book, so I can't really say anything more. Seems like a lot of Nelson Pass/Threshold circuit are very similar to that.
That's the reason why I asked about why all the fancy circuit when the highly regarded and well respected amps use this basic circuit.
ha ha, an even more basic question. Is this art or science? Are people trying to make science out of art?
Last edited:
Alan, please reread my post. Blameless does not specify a topology, but a target of performance. That Douglas likes to implement the blameless concept in a certain topology is another issue.
Jan
I calculate SR requirement for 50Vpeak usingSlew Rate (SR) - Definition, Examples (opamp, sine wave, datasheets) SR=2\pi X Vpeak Xfc with fc=100KHz SR= 50 X 6.28 C 100,000=31.4V/uS. This is calculating to 100KHz. Are you over kill for the sake of overkill?