Which 2SB transistors?

[Tubedriver]

I bought the 2sb176s after the frustration of unable to find good genuine NKTs and AC128s.  I was able to get better sounds from the low gain 176s than the last batch of slim case AC128s which had higher gain.  So far I'm somewhat sold on the 2SBs   I recently purchased 80pcs of the 172s, but not sure how good they will be. 

[jrod]

Just built my first Tone Bender MKII and like 2SB175's better than OC75's. I was very disappointed in the OC75's and starting swapping out different transistors. I have settled with the 2sb175's so far. I really like them in a Fuzz Face, too.

[Tubedriver]

The last batch of slim case AC128s (Germany) were harsh and unstable kinda like the NKTs I bought.  After testing only 25% were worthy.  Even though the 176s had low hfe and not ideal 80-115 they still sounded pretty good and better than anything you can buy off e-bay at rip off prices.  If the 172s I just purchased sound as good as the 176s, I'll be stoked.  I'll report my findings when they come in.     

[mac]

The links I posted above with photos of my Ge transistors are gone. But they are at the bias calculator page

http://www.diystompboxes.com/biascalc/

mac

[jrod]

The last batch of slim case AC128s (Germany) were harsh and unstable kinda like the NKTs I bought.  After testing only 25% were worthy.  Even though the 176s had low hfe and not ideal 80-115 they still sounded pretty good and better than anything you can buy off e-bay at rip off prices.  If the 172s I just purchased sound as good as the 176s, I'll be stoked.  I'll report my findings when they come in.     

What are you building? 80-115 are great in my opinion!

I'd like to hear how the 172's turn out!

[Tubedriver]

I'm making a FF with bias pot.  I use a homemade mockup to easily swap components in and out.  lots of experimentation and checking results.  Like I indicated earlier in the thread, my 167s measured hfe 48 -64.  Mac's earlier posting indicated 176s should be higher than that and he's probably right.  I guess I'm not really sure what my 176s really are, unless they are low gain leftovers.  I got them from MCM.  Any way I ordered some 172s from another vendor.  Who knows what I'll get.  I'll post the results.   

[jrod]

Oh, ok. I've not bought anything from MCM, but have heard the 176's and AC128's were cool.

Sorry, I misread your posting and thought the 176's were in higher than that. 

Those may be good for the first stage of a Tone Bender. Or, the ones in the 60's should be cool for Q1 in a FF.

But, your right, the 176's I have are much higher. Most, IIRC, are about 140-190.

[mac]

2sb172-176-177 datasheet

http://www.datasheetarchive.com/pdf-datasheets/Datasheets-32/DSA-638581.pdf

mac

[Tubedriver]

Wow, this data sheet helps explain, thanks. 

176s S/B Hfe 57 - 140.  Looks like I indeed got 176s in the low to mid Hfe (50.8, 56.5, 57.1, 63.2, 74.5, 83.8, 86.8, 93. from MCM.  However, the 172s I just purchased might not be high enough as the data indicates Hfe 35 - 63.  We'll see when they come in.  I tend to see most opinions on net leaning towards the 172s.  I wonder why? 

I built a FF with 176s Q1 (57.1) and Q2 (93. and it does sound great even with these low gains GEs.  The Strat sound definitely comes through.  Back the volume off for Jazzy Wes and up for Hendrix.   Of course it helps when you have a 68 50W Plexi clone.   

[gmr1]

I've had my hands on at least 1,000 2SB17* transistors through the years. I've never seen any other ones that look like those low hfe ones from MCM with the bold text and no other markings. I was getting them all the time from MCM and until about 6 months ago they always we're the legitimate ones I've seen from every other source, then they stopped getting them.

I can't remember if the 172's had the different letter prefixes to indicated gain groups, as a lot of them did (I'm not at home to check my bins), but I know for sure I ended up with a fair amount that had the right gains for a rangemaster or Q1 in a FF, so I bet you'll be fine.

The 175's might be the best of the series IMO (sound like the others, but I had a higher % fall in the "ideal" gain range). I didn't have as much luck with the larger 177's. The ones I got tested with more leakage than I like - within the acceptable range to most, but I'm used to the Matsushita's having very low leakage.

(Those skinny 128's from MCM are complete garbage, BTW - just a heads-up to anyone that was thinking about getting some)

[Electric Warrior]

The 172s I had were much higher gain than 35-63. More like 90+. A bit high for a germanium Fuzz Face.

[Tubedriver]

I had a conversation with Digitron today.  After prying to understand where their 2SB126s were manufactured, the sales person became frustrated and put me on with their Operations Manager.  He explained that 2SBs are currently being manufactured in Taiwan, hence the new date codes.  If you look on their site the DGE coded units have a 2005 date code.   Not sure how true this is, but it coincides with strange marked non MAT 2SBs being sold abroad by distributors like MCM.   

[Tubedriver]

Yea those skinny 128's from MCM are complete garbage and also being sold on e-Bay from Stuttgart, Germany.  High Leakage - "BEWARE"

[mac]

A couple of things to keep in mind:

1. Most of us use RG test to measure our germs. RG sets the base current to 4uA = 9V/2200 ohms, datasheets can use other base current. Gain is a function of the collector current hfe = hfe(ic) so check in your datasheets the current used.
For example, my 2N388 Texas Instruments are out of specs at 4uA but at higher base currents hfe increase a large amount.
In other words, a datasheet can give you the idea that a particular device is not in the range for a FF, but RG has the last word.

2. If in doubt try to buy matsush*ta, toshiba, sanyo, hitachi. Avoid un-labeled devices. This is the reason I posted photos of my jap germs.

mac

[Tubedriver]

It's true that increased base current increases collector current or gain.  Here's how current relates to transistor gain.   

The current gain in the common-emitter circuit is called Beta (B). Beta is the relationship of collector current (output current) to base current (input current). To calculate beta, use the following formula:

Beta  =  delta Ic/delta Ib

(delta, it is used to indicate a small change)

For example, if the input current (IB) in a common emitter changes from 4 uA to 10 uA and the output current (IC) changes from 4 mA to 10 mA, the current gain (Beta) will be 100.
                                           
Beta  =  delta Ic/delta Ib   =    6 mA/6 uA  =  6 x 10 -3 / 6 x 10 -6  =  100 

This simply means that a change in base current produces a change in collector current which is 100 times as large.

hfe is used in place of Beta. The terms hfe and Beta are equivalent and may be used interchangeably. This is because "hfe" means:

h = hybrid (meaning mixture)
f = forward current transfer ratio
e = common emitter configuration

The resistance gain of the common emitter can be found in a method similar to the one used for finding beta:   

R =  R out / R in

Once the resistance gain is known, the voltage gain is easy to calculate since it is equal to the current gain (B) multiplied by the resistance gain (E = BR). And, the power gain is equal to the voltage gain multiplied by the current gain B (P = BE).


Data sheets only represent a sampling of what to expect from transistors when controls are applied.  Since Germs are so unpredictable data sheets only provide a ballpark example of what to expect.  However, after knowing all this it's still necessary to manually test transistors for your circuits.     

[Tubedriver]

These are the slender can AC128s I got on EBay from Germany.  High leakage and harsh sounding.

[Tubedriver]

The last batch of slim case AC128s (Germany) were harsh and unstable kinda like the NKTs I bought.  After testing only 25% were worthy.  Even though the 176s had low hfe and not ideal 80-115 they still sounded pretty good and better than anything you can buy off eBay at rip off prices.  If the 172s I just purchased sound as good as the 176s, I'll be stoked.  I'll report my findings when they come in.    

What are you building? 80-115 are great in my opinion!

I'd like to hear how the 172's turn out!

Received 80 pcs of GE transistors

2SB172 31pcs 1/2 Mitsubishi/1/2 Matsushita - After sampling a few low leakage, Mits/Mats hfe 90 - 150, Mats sound awesome in FF

2SB175 31pcs Mitsubishi NOS - After sampling a few low leakage, hfe 90 - 128, sound great in FF

AC128 18pcs NOS scraps picked through, high leakage, gains extremely high for FF

[jrod]

Awesome! Thanks for the info!

I have found that all 2SB17X transistors sound GREAT in a Fuzz Face, though I don't think I have tried 172's. Both Mats & Mits that I have tested have seemed to be very stable. In other words, they settle quickly when testing.

The "worst" ones I have (and I quote because they are still very good) are 2SB187 by Sanyo. They are just a little higher leakage (still way under 300uA) and don't settle down as quickly. They seem to sound good, too, but I can't admit that I hear too much difference from one to the other anyway. With the Japanese brands anyway.

[mac]

I have a bunch of jap ge, I should breadboard a FF and try different ge to show differences. Maybe in a decade or two I´ll post the results

Toshiba 2sa49-52-53, 2sb54-56-415 which were very common ge sound very similar, they are all bright and low leakage.
2sa49 and 2sb54 in particular have the right gain for a FF (as far as I tested). And I bought from very different sources.

Matsushita 2sb101/4 family are very bright transistors, I used a 102 for my beloved Rangemaster. 2sb172-175-176-177 are not as bright but fat compared to Toshibas.
2sd352 sound dark, good for those who like a fat and bassy tone.
Unlike Toshibas, Matsushitas leak more.

Texas Instruments 2n1114 have also the right gain, but of the two sets I bought one is leaky and the others sound and leak like Toshibas.
2n388 I have are a little low for a FF but good for any other project, low leakage.

Stick to these jap brands.


mac