NAD: vintage Oliver B120... few questions

mellowgerman · #1 02-19-2013, 11:33 AM

Hi All, just scored a vintage Oliver B120 Uniflex amp. AFAIK these were made by Jess Oliver in the 60's/70's and are considered to be something along the lines of an Ampeg B15 sorta thing. I think that's accurate (if not please correct me). That's about all I know about Oliver amps though.
Cosmetically this thing has taken a beating in the last 40 years or so, but everything works and it sounds fantastic! Pots are a bit scratchy but that's about it. Since the amp didn't have the old back panel anymore, I was looking at the speaker and wondering if it was original... I assume it is but I want to make sure it's running at proper ohms and all. Which by the way, does anybody know if this is supposed to be a 4ohm speaker?
Anyway, the speaker was made by Olson Electronics from Akron, OH. The model is an Olson "Big Rock" speaker. Has the shiny silver dust-cap so that seems correct. I don't see any ohm rating on it but it is stamped: SP-418 1098125.
Can anyone confirm whether or not this speaker is original? Also, if it isn't, is it the right ohm rating for the amp?
Any help is greatly appreciated! Also, of course, feel free to add any other Oliver amps experience stories or interesting facts you might know!
Thanks

mellowgerman · #2 02-19-2013, 11:40 AM

I got the info/schematic/manual from this thread:
Oliver B120 amp
But of course still curious about the speaker and anything else I should know

Zentner · #3 02-19-2013, 11:56 AM

My guitarist and I are Oliver fans... I own 2 and he owns 2 as well. My Oliver P502 has a 15" Jensen in it, but I'm pretty sure it's a replacement. I would assume the amp has a 4ohm minimum, so if the speaker is 4ohms, I would assume there's no extension speaker jack on it, and if all that matches up, you can probably assume the speaker's original.

I do have an old catalogue for Oliver amps I can send you via e-mail if you'd like.

mellowgerman · #4 02-19-2013, 12:00 PM

That would be great! My email is ingohutzenlaub (at) yahoo.com
Also, if it was 4ohm minimum, could I hook an 8ohm speaker up to it? Because I'd love to hear it through my eminence kappa loaded Trace Elliot cab! But obviously, being cautious I want to ask first

Also: no extension speaker jack.

Zentner · #5 02-19-2013, 12:31 PM

If there's no speaker extension, I'm 95% sure it should be a 4ohm speaker in the amp, as you would want to run the amp at potential.

You can hook up an 8ohm speaker to it, but I wouldn't hook that 8ohm speaker up with the current speaker in parallel without testing the current speaker's impedance.

mellowgerman · #6 02-19-2013, 12:35 PM

Gotcha. I was going to run the Trace Elliot 8ohm in place of the one in there now. I do know that running an 8ohm and 4ohm simultaneously is bad news.
I always figured 4ohm was more or less the standard for vintage single-speaker amps with no extension speaker output, but then I found out that some old tube amps ran at a minimum 8ohms... like the Guild Thunderstar Bass amp I used to own. So I always want to double check before making assumptions!

Zentner · #7 02-19-2013, 12:59 PM

Quote:

Originally Posted by mellowgerman

Gotcha. I was going to run the Trace Elliot 8ohm in place of the one in there now. I do know that running an 8ohm and 4ohm simultaneously is bad news.
I always figured 4ohm was more or less the standard for vintage single-speaker amps with no extension speaker output, but then I found out that some old tube amps ran at a minimum 8ohms... like the Guild Thunderstar Bass amp I used to own. So I always want to double check before making assumptions!

Nah, you're safe to run that amp at 4ohms, but I assume 4 is it's minimum.

mellowgerman · #8 02-19-2013, 01:25 PM

Received the catalog email. Thanks for that and all your input, Zentner!
Still hungry to hear more info and input from others too. TB rules!

If I run this amp with only a 8ohm is that safe? Or will it result in higher plate voltage, short-lived tubes and power transformer?

mellowgerman · #9 02-19-2013, 05:59 PM

Just found a sticker on the chasis, written in pen, "10/30/1969". So cool to know the exact day it was made/completed!
Looks like this completed ebay listing implies the speaker is or should be 8ohm...
Seller says: "35 watts into 8 ohms doesn't make a loud earthshaking monster. This thing is about tone! Great singing tone."
http://www.ebay.com/itm/Vintage-Oliv...p2047675.l2557
I took it out of the combo-box and have it hooked up to my TE 8ohm Eminence equipped 1x15 right now and it sounds fantastic! However, if anybody has reason to believe this will hurt it, please let me know because I DO CARE.
In any case, here's a picture

spacebassed · #10 02-20-2013, 12:44 AM

Nice score!! It's nice to see another Guild/Bisonic fanatic enjoying the designs of Jess Oliver. This is basically his improvement on the 60's B15 that he designed while at Ampeg. You might want to try an Altec in there, alot of folks like the midrange cut you get with them in these Theile cabinets.

You'll be fine running this with an 8 ohm load. I'm not sure whether the original speaker in these was 4 or 8 ohms, Mark Gardenberger (Vintage Blue) could probably tell you. Jess actually recommended using a 4 ohm speaker in the B15 (which was designed for an 8 ohm load). Here's what he had to say on the matter:

"After being in the amplifier business for many years, I found out you don't always have to follow the book rules. When it comes to speaker load on a tube amp, I've found you can load a tube amp down to saturation without damaging the amp. You just get more effective power out of the amp. Just as long as the secondary of the output transformer "sees" a path, some resistance, it doesn't matter how low that resistance is, as long as it sounds good, and four ohms is not below the saturation point."

Don't forget to drop by the Ampeg Portaflex club... we accept Oliver owners too! Quite a few of them among us.

mellowgerman · #11 02-20-2013, 08:21 AM

Thanks for the input! I'm absolutely loving the Oliver. Also, I don't know if it's my cab or what but this thing is LOUD for 35watts. I've had 50watt, 100watt, and 300watt tube amps in the past so I thought I had a good idea of what this one could put out... much more power than I thought though. Could easily hang with a drummer and guitarist with this thing. Might be that the Trace Elliot cab is just really efficient too. But either way I'm a happy camper.