Sound Quality Vs. Measurements - Page 326 - diyAudio
Go Back   Home > Forums > Member Areas > The Lounge

The Lounge A place to talk about almost anything but politics and religion.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 11th March 2012, 07:35 PM   #3251
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Hi,

Quote:
Originally Posted by john curl View Post
For example, you can find the 2N5551 bipolar transistor there with 5 pages of graphs and charts on that part ALONE. What a goldmine! All I can do is to suggest. '-)
For learning the Toshiba datasheets for 2SA970/2SC2240 include a complete set of H-parameter vs. Ic/Vce plots. Very instructive and about the most complete Transistor Datasheets I have seen.

Hence I prefer their use over some others, as I do not have to spend days with inadequate tools to generate the same data myself...

As Bob was fond of saying, the bits that you actually need to know about for a given device has been carefully excised from the datasheets...

Ciao T
  Reply With Quote
Old 11th March 2012, 07:37 PM   #3252
dvv is offline dvv  Serbia
diyAudio Member
 
Join Date: Sep 2004
Location: Belgrade, Serbia
Quote:
Originally Posted by ThorstenL View Post
Dejan,



There are Japanese alternatives in all cases that are MUCH better suited.

I admit also to overusing European discrete's when there better japanese alternatives, but I'm learning. Especially BD139/140 are positively stone-age.

Ciao T
Perhaps so, Thorsten, but most Japanese products are not readily available to me. My only alternative would be to stockpile them, and I'm kinda sick of doing that. It tends to suck up money like a vacuum cleaner.

Yes, BD 139/140 are very, very old trannies, but they still make for very convenient and good choices in some applications.

On the other hand, some of those actually old trannies somehow got lost, never got truly discovered for their true worth. BD 249/250 C are an excellent example. They have their voltage limitations, not to be used with more than +/- 40V, but otherwise truly outstanding on sound and robustness. The SGS Thomson version can deliver current peaks of 50 A.

They are often confused with TI's TIP 35/36 C, and while similar and obviously originating from the same roots, they are NOT the same. Even a short look at the TI Data Sheet book will show the BD series to be considerably faster than the TIP series (shorter Ton, Tstore and Toff).
  Reply With Quote
Old 11th March 2012, 07:39 PM   #3253
tvrgeek is offline tvrgeek  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Md
I understand SOA, but one needs to get in the ballpark first. Even I know a transistor won't last very long if you put 110V across a 40V transistor. I also have new direct experience seeing how some rather surprising voltages can show up where one does not expect them from simple faults.

What I find on the WEB is usually the short, or very short version. ( one page), or the long version for parts we can't buy. Of the graphs available, part to part from different vendors tend to have different charts, so I have not had much luck guessing which are the most relevant. The same apparent graph from different manufactures are frequently quite different. About the only general conclusion is no part is very linear in any parameter, but I knew that. A blanket statement "Japanese are better" or "study the charts" I easily accept as wisdom, but not quite as useful from this end as it could be without a place to start.

So, looking for a hint. Say a 2SA1514/2SC4102 over a KSA992/KSC1845. What SHOULD I be looking at? If I were pick them for the IPS? (Ok, I know, you want me to look at FETS there anyway, but let's just say BJT) What graphs would suggest I run them at 1mA vs. 2mA bias for example? 2 inch square charts are a little difficult to have much value.
  Reply With Quote
Old 11th March 2012, 07:47 PM   #3254
dvv is offline dvv  Serbia
diyAudio Member
 
Join Date: Sep 2004
Location: Belgrade, Serbia
Quote:
Originally Posted by john curl View Post
T and bcarso are certainly correct.
The Japanese, at least up to now, have had a much better assortment of bipolar transistors and jfets, than either USA or Europe. Unfortunately, many really good devices (for audio) have been discontinued, leaving us to scramble to find nearly equal alternatives from what is still made.
Tvr's questions are virtually 'scary'! Please learn what voltage breakdown means with a bipolar transistor before applying one in a new situation. Learn what Vceo, Vcb, and Veb mean, and memorize their meanings. Remember, you usually don't have a second chance if you avalanche the transistor, and you MUST study the SAFE AREA of each and every power bipolar transistor, and please note that they are often expressed in LOG-LOG and are difficult to interpret casually without 'uncompressing' them by re-graphing or by very close study.
The best way to learn this is to study a series of data sheets (long form) from a major manufacturer, one after the other, to see the tradeoffs that are made for specific tasks. The best that I can personally recommend is to go to a used bookstore or the internet to get a 30-40 year old, or so Motorola Semiconductor Handbook, or one from another major manufacturer from that era, BEFORE home computers became available, and this was the only way to get the information necessary to design with a specific part. For example, you can find the 2N5551 bipolar transistor there with 5 pages of graphs and charts on that part ALONE. What a goldmine! All I can do is to suggest. '-)
I second the motion!

Not just because JC says so, but because I still own Data Sheet books from Motorola and TI from pre-1980. The data offered there is far more comprehensive than anything I have seen to date, from anyone.

This is my gripe with Japanese transistors - I may have been unlucky and may have missed some really good sources, but I find their data sheets to be, at the very best, scarce. This I find very surprising, given that the Japanese are generally very meticulous, even pedantic.

Just take a peek at Motorola's data sheets for MJ 15024 and such like power devices - when you see any new Data Sheets, from anybody, which are even remotely as extensive and thorough, please let me know.
  Reply With Quote
Old 11th March 2012, 07:51 PM   #3255
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Dejan,

Quote:
Originally Posted by dvv View Post
Perhaps so, Thorsten, but most Japanese products are not readily available to me. My only alternative would be to stockpile them, and I'm kinda sick of doing that. It tends to suck up money like a vacuum cleaner.
If you can finesse the imports on your side, I can probably get you samples for an IRC and arrange production qty's at sensible prices. Heck, you could even make money bringing stuff like that into your corner of the world...

Quote:
Originally Posted by dvv View Post
Yes, BD 139/140 are very, very old trannies, but they still make for very convenient and good choices in some applications.
They made a poor choice IMHO ca. 1985 and my opinion of them has not improved since. Of course, I remember the eastern block, where you had to make a virtue out of noy being able to get the parts you needed and still had to make things work...

Quote:
Originally Posted by dvv View Post
On the other hand, some of those actually old trannies somehow got lost, never got truly discovered for their true worth. BD 249/250 C are an excellent example. They have their voltage limitations, not to be used with more than +/- 40V, but otherwise truly outstanding on sound and robustness. The SGS Thomson version can deliver current peaks of 50 A.
Again, I use them and their like (I do specify a lot of BC... and TIP... Parts) because I know them. My fault entirely.

I usually find better suited parts a few month later on some japanese website. I guess a decade from now I'll only specify Japanese semis... I'm a slow learner.

Ciao T
  Reply With Quote
Old 11th March 2012, 07:53 PM   #3256
dvv is offline dvv  Serbia
diyAudio Member
 
Join Date: Sep 2004
Location: Belgrade, Serbia
And let me add that of all Japanese manufacturers, Toshiba probably has the most informative data sheets, at least from those I have seen.
  Reply With Quote
Old 11th March 2012, 08:06 PM   #3257
tvrgeek is offline tvrgeek  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Md
Even the 2SA970 is not listed on Toshiba's pages, but the 965 is, so let's go there for a moment. Short pages, only 6 charts. Pretend I was going to use it for what they recommend, a driver. Looking at their SOA chart, I am good for Ic of several mA at 100V. Looking at Ic-Vbe it is not very linear until 100mA or so, which would imply I need to be operating at under 10 volts to be very well behaved. For roughly the same voltage, current, frequency and power, this part is not far from the 2N5401, yet it has 5 times Cob. What is that telling me?
  Reply With Quote
Old 11th March 2012, 08:07 PM   #3258
dvv is offline dvv  Serbia
diyAudio Member
 
Join Date: Sep 2004
Location: Belgrade, Serbia
Why is it "your fault", Thorsten?

Don't they do the job you took them for well enough?

Are you sure a Japanese transistor would do the same job audibly better?

If I was asked the above question, I think I'd say offhand that sometimes, perhaps they might, other times no.

I never liked the general market Japanese audio from the 70-ies. It sounded hyped up to me, made to appear very powerful, yet when facing a more complex load, ready to give up very soon.

Over the years, I have exchanged a fair lot of Japanese TO-3 power devices from that period, you will remember that more powerful plastic pack trannies only started appearing in the late 70ies. Given that I can procure only Motorola power devices and be sure I am getting Motorola's parts and not some Foo Manchoo China parts, I naturally gravitated towards them.

And let me tell you what I got to hear - in EACH AND EVERY case, no exceptions, a simple exchange of trannies for Motorolas, WITH NO MODIFICATION of the protection circuits, there was never one single amp which did not sound from better to a hell of a lot better.

Not to even mention what happened to those complex loads when the protection circuitry was adjusted to accomodate for much more powerful devices - as it should be, since I took out 90 and 120 W devices and pushed in 250 W devices. Let's just say that the differences in their SOARs was, er, notable.
  Reply With Quote
Old 11th March 2012, 08:12 PM   #3259
dvv is offline dvv  Serbia
diyAudio Member
 
Join Date: Sep 2004
Location: Belgrade, Serbia
Quote:
Originally Posted by tvrgeek View Post
Even the 2SA970 is not listed on Toshiba's pages, but the 965 is, so let's go there for a moment. Short pages, only 6 charts. Pretend I was going to use it for what they recommend, a driver. Looking at their SOA chart, I am good for Ic of several mA at 100V. Looking at Ic-Vbe it is not very linear until 100mA or so, which would imply I need to be operating at under 10 volts to be very well behaved. For roughly the same voltage, current, frequency and power, this part is not far from the 2N5401, yet it has 5 times Cob. What is that telling me?
It tells you that the prophets of this world were from Japan.

They were the first to catch on to the fact that to profit, you need to make something LOOK like it's the Real Deal, when in fact it could be quite common.

Which is certainly NOT to say that the Japanese have never produced any really great trannies, even in high power devices, which is their weakest spot because they treat transistors as tubes, and in doing so, accept some of the tube weaknesses. Current was never their strong point, although they have come a long way since.
  Reply With Quote
Old 11th March 2012, 08:18 PM   #3260
tvrgeek is offline tvrgeek  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Md
http://www.semicon.toshiba.co.jp/doc...eet_091221.pdf

Unless they have some secret, paying customer set of data sheets, I am not learning much from this.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Quality Control differences = variations in sound quality? KT Class D 3 4th June 2014 12:02 AM
Sound Card for Measurements Marik Solid State 2 2nd January 2012 08:59 PM
Sound Card Recommendations (For Audio Measurements) dchisholm Equipment & Tools 5 16th July 2011 09:40 AM
How to protect sound card during amp measurements? okapi Everything Else 13 2nd September 2008 03:06 PM
Sound cards - test and measurements jackinnj Everything Else 2 5th July 2003 03:02 PM


New To Site? Need Help?

All times are GMT. The time now is 02:32 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2