doctom
14 posts
Nov 21, 2013
2:39 PM
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I just picked up a Bassman LTD off e-bay. I want to do some mods...checked the archives and found some good info but I'm pretty clueless regarding electronics.
Specifically I need big volume without feedback. I'm using a 57 mic. Are there any pictures of the tubes/valves that should be changed out?
Thanks!
Tom
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1847
1324 posts
Nov 21, 2013
5:23 PM
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keep it totally stock.
order a kinder antifeedback pedal
no mods necessary.
the squeal killer is getting great reviews
that may be another good option.
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i get a lot of request when i play my harmonica
"but i play it anyway"
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Greg Heumann
2472 posts
Nov 21, 2013
5:27 PM
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Looking at the back of the amp, you will see the 3 preamp tubes on the right. This makes sense, as they are closest to the input jacks! They are (from right to left, that is, outside in) V1, V2 and V3. My recommendation, tried by many and loved by all: Replace V2 and V3 with 12AU7 tubes. You will now be able to get the volume to 7 or 8 without feedback (if you're not in a small room, where the number will be more like 5 or 6 depending on your mic). Feedback wont' leap out of the amp, it will swell - giving yo enough warning to completely control it with a volume control at the mic.
You will get a bunch of other answers. Most won't go as far as I'm recommending. I think it is important to go this far. Not only does it work, but if you don't like it you WILL have been able to tell what the differences are and can work back in the other direction with higher gain tubes. But this is not "too far" and with decent tubes doesn't sacrifice tone either. Note that this is how the famous Sonny Jr Cruncher, Four-Ten and Avenger amps are set up - and they all share the same basic circuit.
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***************************************************
/Greg
BlowsMeAway Productions
See my Customer Mics album on Facebook
BlueState - my band
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walterharp
1226 posts
Nov 21, 2013
5:40 PM
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If all you are after is volume, most mods will not help you there. They do allow, as Greg said, to use more of the sweep on the volume knobs so make it easier to dial in a volume right before feedback. Many of the more aggressive mods are aimed toward getting more crunch or distortion out of the circuit, giving more of a classic Chicago type tone. This does not give you any more volume, and may actually decrease your cut as they tend to move the amp toward accentuating more of the bass part of the spectrum and it tends to muddy up definition between notes some.
What 1847 says is true. Maybe even more important is getting a good cup and strong tone.. which you may already have, but if you go to a jam where harp players are using the same gear, you will hear some really have it and others get lost on the same gear at the same volumes.
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Kingley
3294 posts
Nov 21, 2013
10:10 PM
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Simply change the V1 preamp valve to a 12AY7 and then you have a great working amp for harp. If you change V3 for a 12AU7 as well you'll get an even warmer, rounder tone that is very nice for lower volume gigs. In my opinion if a Bassman LTD with a 12AY7 in V1 can't get you the volume you need onstage, then you need to play with a band that isn't playing at stupid volumes. Another thing I'd always recommend doing is micing up all the amps used by the band onstage. This allows you all to play at sensible volumes and get a decent mix through the PA in the room.
The points about mic cupping technique and a strong acoustic tone is also a very important one. It cannot be be overstated because it makes a huge difference.
"Note that this is how the famous Sonny Jr Cruncher, Four-Ten and Avenger amps are set up - and they all share the same basic circuit."
Sorry Greg but that isn't quite right. They are very different circuits. About the only real similarities are that they all use 2X6L6 power valves, use valve rectifiers and have V1, V2 and V3 valves. The circuitry that joins those valves together is markedly different though and valve swaps that work well for a Sonny Jr won't necessarily work well for a Bassman LTD.
Whilst I think about it over at www.bluesharmonica.com they have a video series called The Bassman Chronicles, where they take a Reissue Bassman and make a number of changes to it, to make it more harp friendly. It might be worthwhile subscribing and watching those. There is also a huge amount of other information on there that is worth the price of admission. The artist interviews on their own are well worth the cost of subscription.
Last Edited by Kingley on Nov 21, 2013 10:19 PM
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doctom
15 posts
Nov 22, 2013
1:05 PM
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I ordered 2 12AU7's and a 12AY7. I might end up the anti-feedback pedal too but I'll try the tubes first.
Thanks...you guys are great!
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