Oc 81's

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guitar_dude27
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Greg
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Post by Greg »

With a Hfe of 45.. I'd say not very useful for most pedal applications:
http://www.datasheetarchive.com/OC81-datasheet.html
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Post by Scruffie »

OC81's sound pretty awesome in the builds i've quickly socketed them in, I think the D version is useless though... and mine were a different brand (british mullards) so no clue if that will have an effect.

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Post by Greg »

Mullard OC81D is supposed to be the Holy Grail for Tonebenders.
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Post by Scruffie »

I have Both 81s & D's I'l have to try and socket both out (building another tone bender soon), but I remember reading on a thread here someone saying against using the D's... all I know is it's a driver for the 81.

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Post by Greg »

The OC81Ds are the ones that companies like D*A*M and Pro Analog charge BIG dollars for when they can get them.

From D*A*M website:
"our MKII will be fitted with high quality British made Mullard,Philips,NKT(Newmarket)germanium transistors to ensure the same lush fuzz tones that the originals have. Your MKII will usually be fitted with a trio of OC75's but I have used many different Mullard types in the past including OC71,OC78D,OC82D,OC84 and when available the legendary OC81D's."
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Post by guitar_dude27 »

Yea im eying them for a tonebender MKII clone (wanted one forever) but as they are not Mullards and high voltage(?) im nervous.

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Post by Greg »

guitar_dude27 wrote:Yea im eying them for a tonebender MKII clone (wanted one forever) but as they are not Mullards and high voltage(?) im nervous.
Yeah.. they're expensive.. and no way of knowing what gain they'll be (always a potential trap buying Germaniums off Ebay) or how they'll sound.
You probably know, but there are new production transistors for sale at times that are marked as OC81Ds too.. beware of that one ..
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Post by soulsonic »

I thought it was the glass ones that everyone wants. Though, there are some supposed current production black glass ones that everyone who's tried them says are bad.
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Post by Scruffie »

Is there a black glass OC81? I've got some 71's in glass but i've never seen an black glass 81 mentioned anywhere.

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Post by soulsonic »

It was something I saw on the D*A*M forum... people were complaining about them being junk. I think the seller was in Germany. I don't remember what brand was on them, but it definitely wasn't one of the famous brands.
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Post by guitar_dude27 »

The (Mullard) 81ds ARE supposedly the Holy Grail for tonebenders. Supposedly better than than regular 81's, the Ds were made specifically for audio driving applications(?). But after this advice and researching im thinking these are no good. I made the mistake of buying five Japanese oc-81ds awhile back only to find out they have a rating of about 50.....Any ideas for good use?

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Post by Scruffie »

Well if you look at this Datasheet http://www.datasheetarchive.com/downloa ... t50513.pdf
The OC81 is shown as only having 45 hFe so... perhaps the ones with 50 are correct? I realise there not the driver but how much more is the driver going to have.

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Post by slim_blues_boy »

guitar_dude27 wrote:What do you think of this?
https://cgi.ebay.com/1x-Transistor-OC81 ... 2|294%3A50
anyone already try this?
very expensive for untested transistor, even for Mullard OC81D I think.
I never saw OC81D like that. and there is no info about this item on the listing :hmmm: .
anyone have information about this OC81D (manufacturer, year production, etc)?

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Post by Greg »

There's a link to the manufacturers datasheet in the second post of the thread.
That's probably as good as you'll get.

I agree that they're pricey for an un-tested and probably low gain transistor.
OC81Ds are hard to come by though.
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Post by Scruffie »

I have several Mullard OC81 and OC81D's.. they look nothing like that.. and they are definitley original (salvaged from radios, the OC81's even had copper shielding brackets...)

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Post by Greg »

The ones listed aren't Mullards...
They're Zaerix.
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Post by slim_blues_boy »

Greg_G wrote:There's a link to the manufacturers datasheet in the second post of the thread.
That's probably as good as you'll get.
ups yes, there are datasheet. but they only mentioned gain for OC81, not OC81D.
if OC81D has same gain with OC81, 45 is average gain stated on the datasheet, then they're not too different from new production of OC81D.
Greg_G wrote:I agree that they're pricey for an un-tested and probably low gain transistor.
OC81Ds are hard to come by though.
I can say that 90% impossible to get Mullard OC81D. I bought some OC81/OC81D several month ago, with high price, but I only got crap, leaky transistors.

I'm still looking for nice OC81D, but I'm skeptic about it.
anybody have some to share with me :lol: ? hehe....

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Post by zedthewizard »

apparently robert keeley stocked up some mullard oc81d transitors and put out a ltd. ed. fuzz called black glass that has some really nice demo videos. i once had a tonebender with oc81 transistors and it was too smooth. keeley's pedals seems like it can be a nasty rock / blues machine.

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Post by beedotman »

zedthewizard wrote:apparently robert keeley stocked up some mullard oc81d transitors and put out a ltd. ed. fuzz called black glass that has some really nice demo videos. i once had a tonebender with oc81 transistors and it was too smooth. keeley's pedals seems like it can be a nasty rock / blues machine.
Those are not Mullard devices. It's current production transistors from DSI (Germany).

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