Search found 21 matches

by drbob1
Wed Feb 19, 2014 4:23 am
Forum: Technical
Topic: OR120 microphonic v1
Replies: 5
Views: 1041

Re: OR120 microphonic v1

Which is why you'll find that a short or medium plate tube will work much better in V1 than a long plate-even if it's not technically microphonic, the increased gain after the tube will amplify any ringing induced in the plates and it'll be functionally microphonic. Smaller plates, less shaking…
by drbob1
Mon Jan 27, 2014 5:31 pm
Forum: Technical
Topic: 6P14P-EV for OR15?
Replies: 7
Views: 1978

Re: 6P14P-EV for OR15?

I've got em in a 65 AC30 (been there for 5 or 6 years) and they've sounded great all the way along. If I could find a bunch of em, I'd buy em!
by drbob1
Thu Jan 09, 2014 8:28 pm
Forum: Technical
Topic: 20 Watt OR120
Replies: 14
Views: 2653

Re: 20 Watt OR120

You might want to drop the wall voltage slightly with a Variac or the transformer issues we talked about earlier-would put you back to 470…
by drbob1
Tue Jan 07, 2014 7:47 pm
Forum: Technical
Topic: Speakers for OR80 1972 Combo
Replies: 5
Views: 912

Re: Speakers for OR80 1972 Combo

Only had it home 2 days. Into a closed/open back cab with EV alnico SROs? Meh…
Into the Orange 412 with a mixed bag of original Fanes? Now THAT's what we're talking about! Great tone, crunch and touch sensitivity… I'll try out the V30 cab tomorrow.
by drbob1
Tue Jan 07, 2014 7:45 pm
Forum: Community Discussion
Topic: NOAD: 72 OR80
Replies: 3
Views: 626

Re: NOAD: 72 OR80

Right now I've got a couple of NOS American preamp tubes in her and old stock Tesla power tubes. I picked those because the NOS power tubes I have are Siemens and the plate voltage in the amp is running at 520v on wall power. If I decide to plug it into my Variac at about 106 it gives me 470 on the ...
by drbob1
Mon Jan 06, 2014 3:59 pm
Forum: Community Discussion
Topic: NOAD: 72 OR80
Replies: 3
Views: 626

NOAD: 72 OR80

Some of you may have seen the threads on the tech and serial number forums about my OR80 head. Finally got her home from the tech (recapped, new pilot light, bias pot, NOS tubes) and had a chance to play. I tried it thru a pair of old EV SRO alnico's (since JBLs were one of the original speaker opti...
by drbob1
Mon Dec 30, 2013 3:16 am
Forum: Serial Numbers
Topic: Oldie Orange Matamp #006
Replies: 35
Views: 28678

Re: Oldie Orange Matamp #006

I wondered why the info on my or80 hadn't made it onto the site. Sorry to hear that you're backlogged!
by drbob1
Wed Dec 25, 2013 1:38 am
Forum: Technical
Topic: Speakers for OR80 1972 Combo
Replies: 5
Views: 912

Re: Speakers for OR80 1972 Combo

I've got closed back cabs with Greenbacks, H30s, Fanes and V30s, as well as semi open with SRO EVs, EVM12s and JBL E120s so I'll be able to try those, but no open back cabs with them... Any other thoughts?
by drbob1
Tue Dec 24, 2013 9:44 pm
Forum: Technical
Topic: Speakers for OR80 1972 Combo
Replies: 5
Views: 912

Re: Speakers for OR80 1972 Combo

Alrrrriiiggght, let's make the question simpler. Any suggestions for speakers for an OR80 combo? Rather avoid the stock G12H30s since I would undoubtedly blow them up!
by drbob1
Thu Dec 19, 2013 6:23 pm
Forum: Technical
Topic: Speakers for OR80 1972 Combo
Replies: 5
Views: 912

Speakers for OR80 1972 Combo

So, the chassis is nearing completion, and with the Variac I've got at least a temporary solution for the B+ and some tubes that're working. Now I've gotta figure out speakers. I have a Ceramic Weber Thames, which is supposed to be a copy of a Fane, although others say it sounds a bit more Celestion...
by drbob1
Mon Dec 16, 2013 4:19 pm
Forum: Technical
Topic: Tubes for 72 OR80?
Replies: 15
Views: 1915

Re: Tubes for 72 OR80?

Headed over to the tech with some tubes and my variac later this morning. With no tubes in place he measured 540v so I'm guessing in excess of 500v with the tubes in there. It's apparently a bit of a gamble with Siemens tubes at 500v, and at $100 a pair, not sure it's a gamble I want to take. The tr...
by drbob1
Sun Dec 15, 2013 9:33 pm
Forum: Technical
Topic: Tubes for 72 OR80?
Replies: 15
Views: 1915

Re: Tubes for 72 OR80?

Have you seen this before:

http://www.geofex.com/Article_Folders/v ... ntvolt.htm" onclick="window.open(this.href);return false;

Using a 10v AC transformer to shave 10v off the input voltage dropping the B+ by around 10%?
by drbob1
Sun Dec 15, 2013 5:10 am
Forum: Technical
Topic: Tubes for 72 OR80?
Replies: 15
Views: 1915

Re: Tubes for 72 OR80?

I'm drawing a blank on what you actually mean here… The primary windings are not independent? just different taps off the total primary winding? So if you wire one end of the 240v winding to one side of the cord, and the same side of the 110v winding, you're in effect using a 130v winding?
by drbob1
Sat Dec 14, 2013 6:42 pm
Forum: Technical
Topic: Tubes for 72 OR80?
Replies: 15
Views: 1915

Re: Tubes for 72 OR80?

No one has any ideas? Over at TGP the amp/tube experts are suggesting (as I thought I'd heard before) that the RFT/Siemens tubes aren't happy at more than 460+ plate volts. And several have suggested that an OR80 plugged into modern wall voltage is running closer to 550. Anyone?
by drbob1
Fri Dec 13, 2013 9:57 pm
Forum: Technical
Topic: Tubes for 72 OR80?
Replies: 15
Views: 1915

Tubes for 72 OR80?

The caps are in, handle fixed, bias adjust pot neatly installed… Now I have to decide on tubes (came with a dogs breakfast of assorted modern tubes). Will my Siemens EL34/6CA7s (Germany) handle the B+? I do have some Mullards but I'm kinda saving those for a rainy day… Also, any suggestions about pr...