Shaggzilla
1 post
Oct 11, 2008
8:14 AM
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I just bought a new amp to try for harp. I normally play through a mid 60"s Alamo Challenger 5 watt tube amp (it's just a poor man's Champ). I can get it to that sweet spot before feedback occurs.
My new amp is a mid 60's Silvertone 1482. It is a 15 watt amp that is similar to a Fender Deluxe. You can bridge from the instrument input to the microphone input and do some really cool stuff (maybe). I can't even turn this amp to 3 before this thing howls.
I am using a JT-30 mic with a Shure CM element in it. The amp uses 2-12ax7 pre-amp tubes. 2-6v6 power tubes. 1-6x4 recto tube and a 6au6 as a phase inverter (i think). It has a 12" speaker (original - alnico magnet). I get a pretty good cup on the mic. I stand across the room from it. It should be a sweet amp, but i can't get hardly any juice out of it before feedback. I'm lost.
Any filter cap changes that I might want to do. I've heard that adding resisters to drop the plate voltage on the pre-amp tube helps. By the way I have also done some tube swaps. I've tried a 5751, 12ay7 and it still howls. 12au7 worked, but just seemed to suck the life out of the amp.
Any thoughts.
Thanks,
SHAGG
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Zhin
47 posts
Oct 11, 2008
9:28 AM
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I really believe you should purchase Adam's 1 hour lesson on amplification if you haven't. He offers 20 years of solid information and you can DEFINATELY use for ALL your equipment. It couldn't be more perfect for your type of gear!
And you're right about lower gain tubes sucking tone. Personally I'd only swap the input (1st gain stage) tube with a 12AT7 and that's it. Yes that's more gain than a 12AY7 but if you follow the next tip, it MAY actually work.
1 thing that most people are gonna suggest is use a smaller speaker cone. No more than 10". The conventional theory that you're gonna hear anywhere is that feedback frequencies occur more often with 12" and beyond. Go with multiple 10" cones if you need more. I don't know the details about your particular speaker, maybe it's special enough to not need to be changed but I suspect that really could be your main culprit.
And really, the lesson on amping that Adam gives is worth more than what you actually need to pay for which is 5 USD only. Even if my suggestions actually end up solving it but I wouldn't really know since I never tried your setup before.
The direct link to it is here:
http://www.tradebit.com/filedetail.php/3837014-amping-the-harp-zip
Good luck!
Last Edited by on Oct 11, 2008 9:46 AM
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Shaggzilla
2 posts
Oct 11, 2008
10:05 AM
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I bought the Vid last night. It's pretty tremendous! I have some old 10" alnico organ speaker lying around. I may remove the original speaker, board and grill cloth together (to keep the original stuff intact) and put a new board and grill cloth in with one of those speakers and give it a try. I have a 12at7 somewhere. I may try it as well.
Thanks
Shagg
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Zhin
50 posts
Oct 11, 2008
6:26 PM
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Wonderful!
No regrets about the video? ;)
And please, PLEASE let me know how things turned out. I'm anxious to know!
And it's my pleasure too by the way. I love helping out.
Last Edited by on Oct 11, 2008 6:28 PM
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Shaggzilla
4 posts
Oct 13, 2008
10:40 PM
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No luck. I moved from the 12" to the 10" speaker. Had to re-wire from 4 to 8 ohm. Put the 12at7 if the first position and could not turn it up to 3. there was a TON of work to make this move and no pay off. Any other thoughts? I'll keep messing with this thing later. Thanks.
Matt
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Zhin
58 posts
Oct 13, 2008
11:15 PM
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Ack!
Ok, before I even continue I just want to make it clear that all the advice I can offer you are very generalized but tried and tested... So chances are most people who do have something to say, are most likely to tell you the same things.
Ultimately, if you find alternative ways to help fix your problem then go with that. ALWAYS TRUST YOUR OWN EARS at the end of the day no matter what ANYONE tells you. My intentions are clearly to help and nothing more and that's all I can promise. I can't promise if I can totally solve your problem as I can't be physically there and I'm no pro to begin with.
Personally I think not all is lost, it's part of the process. Now you KNOW that you don't need to worry about the speaker for example. Because you will inevitably be told A LOT about that particular area. It's inevitable, you would have eventually been told by someone else if not me to try a smaller speaker.
Some other things I can suggest is that try to systematically back down on the mids and highs. Also, unless you can get away with it without feedbacking, most "presence" type controls and buttons on an amp really cause massive amounts of feedback. So turn those off first if you actually have them...
The other thing, try other tubes in input/first stage gain.
I'm using a 15watt amp too and I can vouch for the fact that they are a real challenge to conquer when dealing with feedback issues.
I dug up some random info like this page: http://www.regiscoyne.com/silvertone1482/
I know it's a different year model but from the looks of it even a guitar player thinks that it's a little on the hotter side without much bass end. That's a major indication that it's very feedback prone. Furthermore he expressed that it's very similar to a Deluxe. If you noticed even Adam's Deluxe is a little on the wild side... very prone to feedback. I suspect this amp might have a little too much gain for it's own good. So bear that in mind...
Now... this is seriously merely an opinion of mine and I could be dead wrong. Perhaps I shouldn't even suggest it... but know the saying "some things are just not meant to be"?
I wish you the best. Please don't hold anything against me ok? No one else seems to have anything to say except me so at least I know I've really tried.
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Shaggzilla
5 posts
Oct 16, 2008
9:13 AM
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I appreciate the help. I'm going to try to swap some filter caps and put a resister on my preamp tube to lower the plate voltage. These should help. If not, i'll just sell the amp. I think that it will work. I'll keep you posted. thanks for the advice and research you did on my behalf.
Shagg
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Guest
Guest
Oct 16, 2008
10:18 AM
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Hi Shagg, I always thought the Silvertone 1482 was supposed to make a good harp amp.
I would post a request for help on either Harptalk the Yahoo forum or Weber Speakers harp forum, before you make any serious changes.
I am sure the knowledge is out there.
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