2 KT88 ORMAT?

Maybe someone can help you date your Orange Amplifier?

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ting_tang
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2 KT88 ORMAT?

Post by ting_tang » Mon Sep 23, 2013 12:24 am

I just picked up an old Orange Matamp head with a 2x12 cab today and haven't been able to find much information on its history. The head has a 2 kt88 power section which I tried to verify on the Orange Amp Field Guide website, but I was not able to find a head on there with matching specs. The back panel is missing so no luck there either. The serial number on the power section flaked off of the chassis in transport to my home, but i remember it saying OR 148, and the preamp says OR 138. the most peculiar thing is that my amps "echo" send and return are located on the far right of the front panel with the power switch to the left of the jacks. All of the other pics I have found have these features reversed. the chassis are loaded into a OR200 style sleeve, but with no side handles. I uploaded some pics of he amp to photobucket for anyone who is interested to look at. any help will be greatly appreciated

http://s1194.photobucket.com/user/ting_ ... rary/ORMAT" onclick="window.open(this.href);return false;

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Re: 2 KT88 ORMAT?

Post by bclaire » Mon Sep 23, 2013 12:40 am

That amp was on here just recently... glad to see the inside shots since we thought it was a four tube but clearly never had more than two output tubes.

This amp seems to be an undocumented part of Orange history - I've seen a couple of OR148's lately...

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Re: 2 KT88 ORMAT?

Post by bclaire » Mon Sep 23, 2013 12:42 am

Was it this one?

http://baltimore.craigslist.org/msg/4014275927.html" onclick="window.open(this.href);return false;

ting_tang
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Re: 2 KT88 ORMAT?

Post by ting_tang » Mon Sep 23, 2013 12:56 am

Yup...just snagged it today...when I got it home I took it apart to clean it up a bit and to see if any monkey business had occured. It seems pretty well stock apart from the acorn shells that some dastardly varmint had stashed inside the power chassis. I did verify that the chassis is steel so I'm assuming its not one of the Fleetwood amps. I wasn't aware that this particular amp wasn't discussed before. It probably could use a good servicing as there is a pretty nasty hum going on. Thanks for the quick reply

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Re: 2 KT88 ORMAT?

Post by bclaire » Mon Sep 23, 2013 1:03 am

Let us know how it goes! Would love to hear a sound clip when it's all together and working right!

ting_tang
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Re: 2 KT88 ORMAT?

Post by ting_tang » Mon Sep 23, 2013 1:18 am

Just found the original thread for this amp..I can verify that it is the same amp in question. I will attempt to contact matamp this week to see if iI can get any clarification on its history. I've repaired and modded a few amps in the past but none apparently this rare. I wouldn't want to butcher this thing...any ideas on knowledgeable people to consult in getting this thing firing on all cylinders?

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Re: 2 KT88 ORMAT?

Post by bclaire » Mon Sep 23, 2013 10:14 am

ting_tang wrote:Just found the original thread for this amp..I can verify that it is the same amp in question. I will attempt to contact matamp this week to see if iI can get any clarification on its history. I've repaired and modded a few amps in the past but none apparently this rare. I wouldn't want to butcher this thing...any ideas on knowledgeable people to consult in getting this thing firing on all cylinders?
I think you're on the right track contacting Matamp... I'd call them first and describe the amp to them and see if they can offer some advice. If I recall, they're not great with email so that's why the recommendation to call....

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Re: 2 KT88 ORMAT?

Post by jontheid » Tue Sep 24, 2013 3:38 am

The first thing that needs to be sorted with this amp is the awful and dangerous mains wiring lash-up.

As it is there could well be mains voltage on the pins on the original socket when the amp is plugged in using the other lead that has been soldered in.

You can get an original (but expensive) plug to make a new mains lead using the original socket from here: http://www.voxshowroom.com/northcoast/v ... ctors.html" onclick="window.open(this.href);return false;

Or you can use these mains sockets to convert to IEC from here:

http://uk.rs-online.com/web/p/iec-connectors/2378894/" onclick="window.open(this.href);return false;

Apparently these are designed to fit into the original mains socket holes and the bolt holes are supposed to line up so no drilling required.

Cheers
Jon

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Re: 2 KT88 ORMAT?

Post by a.hun » Tue Sep 24, 2013 6:54 am

jontheid wrote:The first thing that needs to be sorted with this amp is the awful and dangerous mains wiring lash-up.
...you can use these mains sockets to convert to IEC from here:

http://uk.rs-online.com/web/p/iec-connectors/2378894/" onclick="window.open(this.href);return false;

Apparently these are designed to fit into the original mains socket holes and the bolt holes are supposed to line up so no drilling required.


Cheers
Jon
I'd strongly suggest going for the IEC option. That looks like a neat solution to the old problem of replacing old (dangerous and technically now illegal!) Bulgin sockets with IEC ones. Up 'till now I'd not come across any IEC's which would quite fit into the old round Bulgin hole. Even the smallest ones were just fractionally too large so the hole needed marginally opened out. My old tech:
John Phillips (http://www.thegearpage.net/board/showthread.php?t=62011 wrote:No, I will not drill holes in the front panels for any reason, and I'm very wary of drilling them in the back too (certainly on any amp with is in decent original condition). But I will also open out the Bulgin socket to take an IEC mains lead, if requested. I don't consider that an important loss of originality either.

Neither do Marshall BTW - if you send an old amp back to them for an overhaul, it comes back with an IEC and new selectors. It's a legal requirement in the UK.
Being a very good tech he always took care to do it as unobtrusively as possible. See posts #8 and #10 here:
http://www.thegearpage.net/board/showth ... p?t=290089" onclick="window.open(this.href);return false;
The then 100% original DR103 he mentions working on is now mine. (Mullard EL34s were since replaced, and it now does need a first ever cap job, but it is otherwise 100% as per 1974 and working A1.) John did a very neat job with the mains socket and if anyone ever wanted to replace the original Bulgin (supplied when I bought it!) it would actually cover the minor surgery completely --> invisible. 8)

Better still not to need to file those corners at all of course. Neat idea!

BTW congratulations on the ORMAT and cab ting_tang. Bit of real history there. Good for you taking that project on. Transformers okay? Speakers?


Andy.
aNDyH. :wink:

Ever tried to outstare a mirror?

In the bathtub of history the truth is harder to hold than the soap, and much more difficult to find!

ting_tang
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Re: 2 KT88 ORMAT?

Post by ting_tang » Tue Sep 24, 2013 11:26 am

Thanks for part links, I'll have to look into that. I too don't really like the way that "repair" was handled. I also noticed that they have the ground and neutral reversed...maybe in an attempt to quiet that hum. As for the rest of the amp it has some paint chipping and some cosmetic dings, but the tranny's seem to be rock solid, and the internals look pretty clean at a glance also. I believe that all the tubes are stock with 2 Genalex KT88s, 2 Mullard 12ax7s in the pre, and 2 Brimar 12au7s in the power section. I feel comfortable with doing relatively non invasive repairs like replacing the mains line and replacing some of the electrolytics, but those cap cans are something I wouldn't try to mess with on this guy with my limited setup. I attempted to contact matamp yesterday, but to no avail. The cab seems to be totally stock also, and working fine I'll try to post pics of that later

Thanks

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Re: 2 KT88 ORMAT?

Post by bclaire » Tue Sep 24, 2013 12:49 pm

I'm the same regarding electronics repair - I can do simple, minimally difficult repairs but when it comes to caps, hello amp tech!

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Re: 2 KT88 ORMAT?

Post by Gladmarr » Tue Sep 24, 2013 3:30 pm

There is one member on the Vintageamps orange forum who has a 2xKT-88 amp like yours. His has a pair of tube rectifiers, so it's slightly different from yours. He, unfortunately has no schematic or any other technical info, but you two might be able to compare notes.

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Re: 2 KT88 ORMAT?

Post by Orphin » Thu Sep 26, 2013 12:22 pm

These are interesting amps.
According to the book Matamp at 60 these were only made as prototypes for Fleetwood Mac for their US tour, and were disassembled after the tour. I have all my books packed in moving boxes now as I'm moving on sunday so I can't quote anything.
In the book of Orange however it says that about 50 of these amps were made. It also says that these amps were fitted in OR200 sized sleeves which obviously yours is.
Both books claims however that they were all made on aluminuim chassis, but a member of the Matamp forum and Vintageamps forum called Amoun claims that he have seen several of these 2 KT88 amps that have been build on steel chassis. If that is true, both books are incorrect.
Is your amp build on alu or steel chassis?
If it's on aluminium chassis it worth more, that's for sure.
If you contact Matamp, don't email; call. Try to get hold of either Derek Thompson or even more preferably John Firth. John doesn't work there but usually visits on saturdays.
Another person you can try to contact is Mick Dines at Orange. He worked at the Orange side of Orange Matamp back in the days.
These three people have contributed with their knowledge and their memories to both of these books, so chances are thet they don't remember these steel chassis 2 KT88 amps, but it's worth a try.
Mick did remember some interesting details about my Ormat though that aren't mentioned in any of the books.
If you do come up with any more info on these amps, please share.
David
I'm speaking out of my a$$. Yours might differ.

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Re: 2 KT88 ORMAT?

Post by jontheid » Thu Sep 26, 2013 1:04 pm

There are solid-state rectified 2xKT88 OrMat slaves as well:

This is one apparently:

Image

Image

Orphin
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Re: 2 KT88 ORMAT?

Post by Orphin » Thu Sep 26, 2013 8:35 pm

jontheid wrote:There are solid-state rectified 2xKT88 OrMat slaves as well:
Sorry. My post was only refering to the OR100.
David
I'm speaking out of my a$$. Yours might differ.

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