| Re: SSM2210 or LM394CH [message #204034 is a reply to message #203732 ] |
Wed, 06 December 2006 11:11   |
 Jim Williams
Messages: 462
Registered: May 2005
Location: beautiful carlsbad, CA |
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If one compares the test signal from the AP's CCIF IMD tests to that of a complex musical waveform, there is one factor missing from the IMD tests, dynamic reaction. Steady state test tones are operating at a fixed, high level. Music waveforms have low, medium and high frequencies all working at the same time with an enormous amount of dynamic range. An example is jazz recordings with percussion. Some of those high frequency tones off a triangle are fighting with middle and low frequencies for attention. The amplitude difference can be over 1000/1 from a snare drum hit to that triangle getting brushed. If the AP could accuratly output a 1k tone at 0 db along with a 16k tone at -60 db, we might get close to approximating the dynamic range of music, especially if the amplitude of both waveforms were to be modulated. I'm still waiting for the minds at Audio Precision to write this test for me.
A great test bed for the LM394 is the front end of a mic preamp. If one sets this test up, one will find that the 394 is noticable darker in the transients than the MAT-02, or any number of low cost Japanese transistors. Try it and see, I did back in the 1980's and haven't looked at a LM394 since.
Jim Williams
Audio Upgrades
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| Re: SSM2210 or LM394CH [message #204054 is a reply to message #204034 ] |
Wed, 06 December 2006 11:53 |
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resolectric
Messages: 249
Registered: May 2004
Location: Europe |
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| Jim Williams wrote on Wed, 06 December 2006 17:11 |
...
A great test bed for the LM394 is the front end of a mic preamp. If one sets this test up, one will find that the 394 is noticable darker in the transients than the MAT-02, or any number of low cost Japanese transistors. Try it and see, I did back in the 1980's and haven't looked at a LM394 since.
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I agree.
My console (32 input, 26 mic inputs, analog, Altair, made in Spain, customized in several sections of its circuit) is factory fitted with SSM2210s in every Mic input.
During maintenance, besides discovering some traces of previous repairs (bought the console used, non-functioning) i found six channels where the SSM2210s had been replaced with LM394s.
I started listening carefully to how each of the different transistors sounded like and decided to come here and ask about these and the apparent differences in sound between them. After listening it became clear that the LM394 channels present more saturated sibilants on vocals and a less "open" (less "airy") sound on acoustic guitar.
The LM394 really sounds "duller" than the cheap 2210.
Since i have the console open i've decided to switch the LM394s to channels fitted with SSM2210s, and vice-versa.
The colour of each transistor's sound follows it, so, it isn't a channel characteristic but the transistor itself that has it's own sound. Unless, there's some misadaptation in the channel circuit that doesn't accept the LM394 as well as a SSM2210.
Now, i got to get some of those MAT02s!
P.S.: Your extremely valuable posts went deeper into the subject than i had ever anticipated, regarding my very basic question, and let me tell you that i am learning a lot from this topic alone.
Thankyou all.
Paulo Miranda
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| Re: SSM2210 or LM394CH [message #328325 is a reply to message #204054 ] |
Thu, 27 March 2008 16:46 |
peranders
Messages: 13
Registered: March 2008
Location: Göteborg, Sweden |
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| resolectric wrote on Wed, 06 December 2006 11:53 |
Now, i got to get some of those MAT02s!
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Save the money and take the SSM2210. Notice also that LM394 is worse in many respects compared to SSM2210/MAT02 but it may not be so in your application.
/Per-Anders
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| Re: SSM2210 or LM394CH [message #330199 is a reply to message #200660 ] |
Thu, 03 April 2008 09:10 |
peranders
Messages: 13
Registered: March 2008
Location: Göteborg, Sweden |
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I have always thought that SSM2210 was a monolith but after further investigation it seems that your are right. 4 nA leakage between the transistors seems little if there was a single chip.
/Per-Anders
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| Re: SSM2210 or LM394CH [message #332344 is a reply to message #203717 ] |
Thu, 10 April 2008 16:36 |
ssltech
Messages: 1877
Registered: May 2004
Location: Florida (previously UK) |
Platinum Member |
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| Jim Williams wrote on Tue, 05 December 2006 11:00 |
I don't have the data sheets in front of me, but listening tests demonstrate this easily. The previous poster has made the same claim. The 394 sounds choked off in the highs. MAT-02's are available from Digi-key, the tightest version is $15. They do make a difference in MCI tape machines, 636 console preamps, Ashley SC50/55 compressors, etc. Try them and hear it for yourself.
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Ah, just re-reading this thread, and I have to modify/correct your interpretation of my post, Jim.
The only real problems which I've had with placing MAT-02s -in one very particular and specified implementation- instead of 394s has been with noise floor, and not anything immeasurable.
Keith
| MDM (maxdimario) wrote on Fri, 16 November 2007 21:36 |
I have the feeling that I have more experience in my little finger than you do in your whole body about audio electronics..
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| Re: SSM2210 or LM394CH [message #332893 is a reply to message #332344 ] |
Sat, 12 April 2008 01:41 |
peranders
Messages: 13
Registered: March 2008
Location: Göteborg, Sweden |
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You mean you've got more noise from a 1 nV/Hz transistor than from a 1.8 nV/Hz?
/Per-Anders
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| Re: SSM2210 or LM394CH [message #332894 is a reply to message #330199 ] |
Sat, 12 April 2008 01:42 |
peranders
Messages: 13
Registered: March 2008
Location: Göteborg, Sweden |
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| peranders wrote on Thu, 03 April 2008 09:10 |
I have always thought that SSM2210 was a monolith but after further investigation it seems that your are right. 4 nA leakage between the transistors seems little if there was a single chip.
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Why says the datasheet title this "Low Noise, Matched
Dual Monolithic Transistor" if it's not monolithic?
/Per-Anders
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| Re: SSM2210 or LM394CH [message #333792 is a reply to message #200660 ] |
Tue, 15 April 2008 13:38 |
Mike Peake
Messages: 40
Registered: September 2004 |
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Learning that these devices differ spectrally gives me pause. A vintage synthesizer, the EMS "Putney"/AKS etc. use the now unobtainable 2C746 as a matched pair for exponential oscillator response to CV. Some versions used hand-matched trannies, glued together. Some folks who modify these for "stable tuning and tracking" recommend using the LM394, but I wonder if this will effect the frequency modulation index with regard to spectrum in a displeasing manner...the audio-rate FM on the EMS is one aspect which other synthesizers cannot approach, and changing it would be a mistake...
Anyone know where to source the 2C746? 
I'm serious if you know where to get the 746, BTW.
Edit: It turns out that there are well-defined measurable differences in performance when using these items for pitch control. From the musicfromouterspace.com web site:
- Good tracking over several octaves (3 to 4).
This used to say "at least 6" but field testing has shown that 3 to 4 is more realistic.
I got lucky on a couple of them is all I can surmise.
- BETTER tracking using the AD SSM-2210 Dual Matched NPN
in place of the LM394. (5 to 6 octaves)
http://www.musicfromouterspace.com/analogsynth/VCO200604REV0 1/VCO200604REV01.html
"Give me the ANALOG and no one gets HURT"
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