AC128's from Czech?

[elebcz]

Exactly! Look: http://uk.rs-online.com/web/0293909.html.

Jan

[Jaicen_solo]

Indeed, however they appear to be suppliers themselves rather than manufacturers.
They're actually based a few miles from my home-town!

[zombiwoof]

Exactly! Look: http://uk.rs-online.com/web/0293909.html.

Jan

Wow, I didn't know anyone was making the larger-package (what is that package, TO-1, I think?.) AC128's.  Really interesting, I wonder how they sound compared to the NOS ones?.  The only AC128's I have seen available here are the Tungsram small-package type, like the ones the OP was considering.  Funny, I didn't see any of those germanium transistors on the Magnetec site.  For the U.S. forumites, they are available here, they cost less the more you buy:

http://www.alliedelec.com/Search/ProductDetail.aspx?SKU=090SPEC&MPN=AC128&gclid=CJ22h9D44qQCFUPr7QodCFNYFQ

I also ran across some NKT275's in that size package that appear to be new manufacture (maybe also by Magnetec) from American Semi,  they are about $5 ea.:

http://store.americanmicrosemiconductor.com/nkt275.html

There is another company called DSI, that is making modern versions of vintage transistors like OC44 and other vintage types, there was previous discussion of them.  The problem that people were running into with those was that most of them were in gain ranges too low to use in the popular pedals that use those types.  That could also be the case with these, and with them being $4-5 a piece it could get expensive buying some to test, hoping they were the right gains.

I wonder if Small Bear is aware of these new germaniums?.  He could probably get a sample to measure.

Al

[Jaicen_solo]

FWIW, I got some AC127's in the later type package that measured aroun the 90hfe mark. They're great in Fuzz Factories.

[DiscoVlad]

Wow, I didn't know anyone was making the larger-package (what is that package, TO-1, I think?.) AC128's.  Really interesting, I wonder how they sound compared to the NOS ones?. 

I recently made a couple of MK2 Tonebenders with the Magnatec AC128s from RS Components. I have no idea how they sound compared to the originals, but everyone who's played with them ends up with a huge grin on their face. They're ridiculously fuzzy.

Of the devices I used, they all measure in RG's test circuit: 100-120uA leakage,  and gains around 100-130.

[zombiwoof]

Wow, I didn't know anyone was making the larger-package (what is that package, TO-1, I think?.) AC128's.  Really interesting, I wonder how they sound compared to the NOS ones?. 

I recently made a couple of MK2 Tonebenders with the Magnatec AC128s from RS Components. I have no idea how they sound compared to the originals, but everyone who's played with them ends up with a huge grin on their face. They're ridiculously fuzzy.

Of the devices I used, they all measure in RG's test circuit: 100-120uA leakage,  and gains around 100-130.

Good info!.  How many did you buy, and did they all fall into that range?.

Al

[DiscoVlad]

I bought 10 since they practically halve in cost from that quantity on, only tested the ones I used in the pedals, so six.

Originally I was going to use some vintage transistors which I inherited, but they were all over the place and a pain to sort, the leakage current was unstable and most had gains around 20-40... The first couple of new ac128s both measured exactly where they should be so I gave up on the old ones at that point.

[Jaicen_solo]

....The first couple of new ac128s both measured exactly where they should be so I gave up on the old ones at that point.

Exactly, hence the reason i've stopped hunting for NOS.

[Pigyboy]

I give Jan at Elecbz I big thumbs up! He is totally on the ball and he ships fast. He has the teflon coated wire for the best price I have found in Europe too.
I am a happy chappy

[skrunk]

any of you guys ever check these ac128s out?
I just got some but the gains seem way off the description.

on one of the bags it reads (for example):

"Q1 for fuzz face -

hfe@Vce=0.7V, Ic=10mA, f=1kHz  ---  84
Icb0 (uA) @ Ucb=0.7V                  ---  2.2"

so I measured using RG's method with a 9.07V battery,
and got

hfe = 47
leak = 0.16v

similarly,

his reading   --   my reading:

83 / 2.9             46 / 0.25
83 / 3.0      --    53 / 0.2
85 / 2.4       --   43 / 0.17
131 / 4.5    --    75 / 0.42
138 / 3.9    --    71 / 0.35
139 / 4.0    --    75 / 0.32
135 / 3.8    --    67 / 0.28


so am I misunderstanding the data?
or is there different measuring methods going on here?

[digi2t]

I bought some sets from Jan for my Skyripper. They worked just fine. If I need more, I'd definately go back to him.

Cheers,
Dino

[chi_boy]

any of you guys ever check these ac128s out?
I just got some but the gains seem way off the description.

on one of the bags it reads (for example):

"Q1 for fuzz face -

hfe@Vce=0.7V, Ic=10mA, f=1kHz  ---  84
Icb0 (uA) @ Ucb=0.7V                  ---  2.2"

so I measured using RG's method with a 9.07V battery,
and got

hfe = 47
leak = 0.16v

similarly,

his reading   --   my reading:

83 / 2.9             46 / 0.25
83 / 3.0      --    53 / 0.2
85 / 2.4       --   43 / 0.17
131 / 4.5    --    75 / 0.42
138 / 3.9    --    71 / 0.35
139 / 4.0    --    75 / 0.32
135 / 3.8    --    67 / 0.28


so am I misunderstanding the data?
or is there different measuring methods going on here?

Did you, or can you try them in a circuit?  I would think the real measure would be how they sound. 

The measuring monster he shows in those pictures on eBay looks sophisticated and intimidating.  Assuming the thing is not just window dressing, I would think the results would be good.  Sorry I can't help with the difference in results.

[elebcz]

Hi skrunk,

I can give you an explanation:

- you use a different I_C for the gain measurement then me
- you have measured leakage by I_CE0 while I have measured I_CB0
- you use a different U_CE then me
- you have done DC measurements of the gain (beta = h_21E = h_FE) while I have provided AC measurement by the signal of 1kHz (h_21e = h_fe)

My more professional approach guarantees to you better results in your circuits. And, of course, a different method gives different figures.

Anyway, you can send trannies back to me if you're not happy with either specs of pedal sound and I will fully refund your payment. (Note: I have no returns from my AC128 eBay sales yet  )

Good luck in your project.

Regards,
Jan (elebcz)
http://stores.ebay.com/elebcz

[skrunk]

thanks for the explanation jan.
your measuring method may be 'more professional' but it doesn't mean better results for me if I'm misunderstanding the data!
I think most people would agree that gains between 80-130 (using RGs method) are good for a fuzz face circuit, and when I saw your gain readings I wrongly assumed
that was what I was getting.

mine are between 47 -75 measured using RGs method, not what I would choose for a fuzz face, though I guess they would work to some extent.
I haven't tried them yet, I will tomorrow and report back.
thanks for your help jan, and the offer for a refund.
I'm just trying to understand all this hfe mumbo jumbo!

so I am missing something here??
which is the right reading to go by, assuming they are both 'right'?
it seems people are getting good results with these, so I'm just a bit confused

[joegagan]

if  rg's tester is built correctly, according to the article, all parts in spec, assuming correctly working voltmeters,  readings should be within  plus or minus 10 % or less. i think.

[skrunk]

thanks for the input joe.
you mean within 10% of jan's readings?

I'm using an RG tester I built on vero a while back which has a 2.2m resistor and a 2k with a 470R (measures 471R) in series, giving 2.471k.
along with a battery that measures 9.01v.
I'm letting each tranny rest a few minutes in the tester before I measure too.

I use this method all the time and the results I get are usually pretty close to readings I might get from smallbear trannys or bgebus, another ebay seller.
but all the ones I measured are way lower than jan's readings, around half in most cases eg: 86 (jan), 43 (me)

[Brymus]

I think what Jan is saying (I may be wrong)
Is that he is providing AC gain,not DC current gain like the RG tester.

I think his main point is if you like the way they sound they are worth the price,if not he refunds the money.

A good test would be to compare (his) with ones (yours) that measure a certain Hfe with the Rg test in a pedal.

[joegagan]

yeah, i guess i didn't allow for temp differences. can make these things vary a lot. the testing is good, but ultimately it has to sound good if we are using it for tone.

[Jaicen_solo]

I think that we need to stop obsessing about specs, and just try the damn things.
I'm formulating a theory that within a Fuzz Face circuit, the gain ratio between the two transistors is more important than the actual gains involved, within reason.
I have some transistors that measure less than 10hfe, that sound great!

[chi_boy]

Well, I bought mine.  Always wanted an AC128 fuzz just for the mojo factor.  I don't think they could be that bad, but I will certainly compare these to the "All American" set I bought from Small Bear.  Those sound really good too, BTW.  But a little less mojo.