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Topic: Oahu Tonemaster amp model 230K |
Dave Zirbel
From:
Sebastopol, CA USA
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Posted 16 Jun 2007 11:22 am |
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Got a great deal on a matching Oahu steel and amp. It has one 12" speaker. The amp is all original and in great shape. Looks brand new! At this point it's useless for steel for great for gritty guitar tones at low volumes. Does anyone know how many watts these things have? Would you reccommend have it gone through to replace caps just becuase of the age? MAybe a grounded power cord? It seems like the tubes are original. The speaker has a tiny magnet on it, What would a more efficent speaker make it louder?
Thanks, Dave
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Dave Zirbel-
Sierra S-10 (Built by Ross Shafer),ZB, Fender 400 guitars, various tube and SS amps |
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Donny Hinson
From:
Glen Burnie, Md. U.S.A.
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Posted 17 Jun 2007 4:33 am
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Most of the old Oahu's were 5-15 watts. Yes, it probably needs a cap job, and maybe a tube or two. Those old "plug magnet" speakers were pretty poor. A modern speaker will give you more volume, but with some change in tone. Some players like it, some don't, but the increase in reliability and punch is worth it, IMHO.
Definitely get a grounded cord put on it! |
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Dave Zirbel
From:
Sebastopol, CA USA
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Posted 17 Jun 2007 9:18 pm
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| Thanks Donny. Do you think it's an 8 ohm load? It doesn't say anywhere and I don't have a tester. Anyway, I dropped in an old 25 watt Celestion speaker and the thing turned into one of the best sounding blues/rock amps I've ever heard. The bottom end is a tad soggy and it could use a pinch more highs. I think I'm going to invest and have a diagnostic and a cap job, possibly tubes. I could see this being a great sounding and usable piece of equiment. I'm playing with some quieter bands these days. The only drawback is that it's not real versitle. You get what you get. The tone stays dirty when you roll off the volume but maybe having it serviced will help. |
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Donny Hinson
From:
Glen Burnie, Md. U.S.A.
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Posted 18 Jun 2007 5:27 pm
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| Dave, most of those old tube amps with a single speaker were 8 ohms. Once in awhile, you'd see 16 ohm speakers, but that was usually with two-speaker amps. It's real easy to overdrive these amps, so keep the input low. A small stomp-box EQ will do some tone shaping if the amps controls are not to your liking. For the best (most articulate) sound, use a speaker with a power rating somewhere near that of the amp. High-power (heavy wattage) speakers generally sound "stifled" when you use them with lower powered amps. For an amp with an output of 15 watts, I'd choose a speaker with a rating of no more than 25-30 watts. |
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Jim Sliff
From:
Lawndale California, USA
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Posted 18 Jun 2007 7:55 pm
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Dave - do not just plug in a speaker and play with an old amp like that. Some are not very forgiving of impedance mismatches. Take the speaker to Radio Shack, tell 'em you are shopping for a tester, and use the speaker as a "test item"..."thanks guys, I'll think about it and be back". Or just spend 15 bucks on a cheap one! But don't play it with that Celestion. Not yet. I've seen a lot of Oahus with 3.2 ohm (4-ohm) speakers, and a 16-ohm can wipe that amp out due to "flyback".
| Quote: |
| the speaker has a tiny magnet on it, What would a more efficent speaker make it louder? |
Magnet size has nothing to do with efficiency OR volume. It usually...because of corresponding voice coil size...gives a slight indication of poweer handling, but not much. It's pretty meaningless. Some small-magnet speakers...low wattage as well...are the most efficient. Not the tightest at high volume, but actually more responsive at low volume. Speaker replacement is up to you, but get all the electronics done first.
Cap job = mandatory. Don't play it again unti it's done unless you want a piece of furniture or a repair bill. 3-prong plug = mandatory for safety.
It may NOT need new tubes - but it does need to be gone over by someone who knows their stuff. Please don't play it until it's been serviced - I have had far too many similar types brought to me as smoking hulks because "it worked, so I thought I'd use it".
_________________
No chops, but great tone
1930's/40's Rickenbacher/Rickenbacker 6&8 string lap steels
1921 Weissenborn Style 2; Hilo&Schireson hollownecks
Appalachian, Regal & Dobro squarenecks
1959 Fender 400 9+2 B6;1960's Fender 800 3+3+2; 1948 Fender Dual-8 Professional |
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Dave Zirbel
From:
Sebastopol, CA USA
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Posted 18 Jun 2007 9:09 pm
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I know that the speaker I put in it is 8 ohms so it should be ok if it's asking for a 4 ohm load, right?
I played the thing for a couple hours already and it seems to be fine. I opened it up and I don't think it has ever been serviced but I don't know for sure. It's real clean inside but the components look old. The tubes may be rare.
Don't worry Jim, I won't attempt any repairs on this. There is a guy up near Sac that is known for his restorations. His name is Skip Simmons.
http://skipsimmonsamps.com/news.html
The coolest thing about this amp is the lighted nameplate on the front! That's probably where MAtchless got the idea! |
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Jim Sliff
From:
Lawndale California, USA
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Posted 19 Jun 2007 5:27 am
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| Quote: |
| I know that the speaker I put in it is 8 ohms so it should be ok if it's asking for a 4 ohm load, right? |
No. Fenders (most) can take a 100% mismatch, but many amps (most Marshalls for example) are not so tolerant.
It may "sound" fine, but lots of amps sound their best right besore they go boom....
I'd really be careful. That thing is a classic to many players, and it the output transformer cooks, you're done.
_________________
No chops, but great tone
1930's/40's Rickenbacher/Rickenbacker 6&8 string lap steels
1921 Weissenborn Style 2; Hilo&Schireson hollownecks
Appalachian, Regal & Dobro squarenecks
1959 Fender 400 9+2 B6;1960's Fender 800 3+3+2; 1948 Fender Dual-8 Professional |
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Dave Zirbel
From:
Sebastopol, CA USA
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Posted 19 Jun 2007 6:47 am
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Thanks guys. I appreciate the input. I guess I'll figure out a way to measure the original speaker unless I get it the tech before.
DZ |
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Robert Szpuk
From:
California, USA
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Posted 21 Jun 2007 7:54 am speaker ohms
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| dave hi, all you need is a cheap multimeter set to lowest ohmage across the [disconnected] speaker lugs. the reading will be lower than the actual designation, ie. 6.8 for 8 ohms or 3.5 for 4 etc. cheap tool good way to safely determine many specs. regards, rob |
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Jim Sliff
From:
Lawndale California, USA
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Posted 22 Jun 2007 11:44 am
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That's what was mentioned before, but Dave doesn't have one - so he was given a way to "use" one while shopping...
_________________
No chops, but great tone
1930's/40's Rickenbacher/Rickenbacker 6&8 string lap steels
1921 Weissenborn Style 2; Hilo&Schireson hollownecks
Appalachian, Regal & Dobro squarenecks
1959 Fender 400 9+2 B6;1960's Fender 800 3+3+2; 1948 Fender Dual-8 Professional |
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