Mullard CV7003

[fretbuzz2003]

Hi,
I'm going to build a Rangemaster Clone and I just purchased some "Mullard" CV7003 transistors (For $3 each it was worth the try) from eBay. I'm wondering if anyone has genuine Mullard CV7003's and what the markings on the case are, so I can tell if these are real or not.

Thanks.

[saros141]

I've got a few (not with me this second), they're the "black bullet" type, marked KB/DG signifying they were made in the Associated Semiconductor Manufacturers plant in Southampton... I think there's a 4-digit date code on 'em too.  They could be exactly the same as the civilian OC44 (perhaps selected for performance and reliability), just with a different designator for the military.  They did this with tubes quite a bit.

There's a shorter metal-can CV7003 out there that's actually made by Texas Instruments.  I have some metal Mullard OC transistors, but I'm not sure if they made an OC44/CV7003 type in the metal can... I'd be interested to hear if they exist.

All that aside, even if your transistors are not "real Mullards", if their gain and leakage are within the right range they should sound great!

[fretbuzz2003]

I think those are the ones! They are the black bullet type and have the KB/DG markings. Thanks! I just hope they aren't too leaky.

I have a few of the metal can ones too. I'm not sure who made them. They have a small circle with a dot in the middle stamped on them.

Thanks!

[saros141]

Well, if you got 'em from Colomor (jmg744) they should test fine, that's where mine came from and I paid over double that, so good on ya!  

Other sellers I recommend highly are highlandermona and minifux1, both in Germany.

[saros141]

Just did a search, I see you did get them from Colomor... I have no idea why nobody else bid on that auction (did you put out some kind of voodo to make everyone forget to bid?) If you do a Completed Item search for CV7003, you'll see that the (IMO) less desirable TI version went for almost 8 bucks apiece.

Anyway, as I remember, mine is Hfe 85 with leakage 85 microamps, using R.G. Keen's circuit and math.  Sounds great, nice shimmery treble and the bass compresses and distorts in a nice way, not too blatty - I find that the transistors I like least in this circuit have a harsher, glaring character to the way they distort, especially when you use a larger input cap.  The Mullard is more chocolatey... like their tubes, really. The Valvo OC44 I have is very similar, but with a jumpier, more dynamic response (doesn't compress as quickly), and very squeaky-clean resolution to the high frequencies, with not quite as smooth of a breakup (could be biasing differences, though).  I've been listening by going guitar > RM > MG Head OTL tube headphone amp > Sennheiser HD580 cans, so it's pretty much a microscope

Have fun building it!

[Bluesgeetar]

Hey saros141.  Where are you getting your info on those markings KB/DG designating they were made in Southampton?  I've scoured the net trying to find that info.  Where did you find it?

[fretbuzz2003]

No kidding, the voodoo curse actually works!  :twisted:

Thanks for the info. I can't wait to finish the pedal!

[Bluesgeetar]

Or maybe you or you guys are just getting on board here!  I got a pile of black bullet CV7003 from Colomor sitting in my inventory.  Also you must not forget that there are many here that buy into that any tranny sounds good BS that is shelled out by many a tone deaf guru.  I guess that is why no one here bids on that stuff.  I don't bid but then again I already bought up a load from Colomor and others. There is a difference bro!!!!!  There ain't no 2N? or BC??? orAC anything gonna do a real good sub for the real things. Course many will disagree and that is were the done deaf thing comes in.  But then again thank God for the gurus sitting around making and designing these wonderful new circuits for us to use for free while we just search and play on the net buying up these vintage parts.  I gots many a many cool old parts!  I ain't designed nuthin!  Just spend my time hunting the old stuff.  Gurus keep up the good work on the new designed stuff!  I be honest!  That Thunderchief knocked me on my ass!!!!!!!!!  Wicked wicked pedal design there.  I immediately put in an order for some J201 from mouser when I heard that mutha!

[saros141]

Hey saros141.  Where are you getting your info on those markings KB/DG designating they were made in Southampton?  I've scoured the net trying to find that info.  Where did you find it?

I can't remember where I found it, I have a couple Microsoft Word documents I must've saved way back, I can email 'em to you if you want... saros141 at hotmail dot com.

FWIW, I do think that pretty much any tranny with the right characteristics can sound good... it's a good-sounding circuit, especially when it's tuned to the tranny... but I agree that certain parts can help to push good into the land of great.  :wink:  ... BTW I just tried a cold-war Russian MPi21D and it was quite nice!

[fretbuzz2003]

The CV7003's finally arrived, but I'm not sure of the pinout. THe case is round and the leads are in line. There is a red dot on the side of the case near one of the leads. I'm assuming the dot marks either the collector or emitter, does anyone know which it is?

Thanks.

[saros141]

red dot = collector

You'll notice that lead is spaced a bit apart from the other 2.  A white dot, a line, an arrow - basically any distinguishing mark - is probably the collector if it's a Ge device.

have fun!

[fretbuzz2003]

That's good to know. Thanks alot!