Adam Pritchard
9 posts
Jul 04, 2013
11:10 PM
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Hi all. Let me start by apologizing for resurrecting a topic that's been discussed here and elsewhere numerous times before. I've read through all that material and have just ended up more confused.
I have recently purchased a Fender Bassman LTD of eBay. I decided to buy one after my previous amp, a Peavey Delta Blues 210, just wasn't cutting it at gigs with my band who, despite my constant moaning at their volume levels, stubbornly refuse to turn down.
From reading through numerous posts on this subject it appears there is no general consensus, but nevertheless I'd appreciate the benefit of all of your collective knowledge and experience on this matter.
So, to avoid any confusion I'm talking V1 to V3 where V1 is furthest from the power tubes (closest to the input jacks) and V3 is next to the power tubes (I believe this is the phase inverter). From what I've gathered people have very different set ups here. Here's a selection (apologies if I've confused previous posts:
Dave Barrett on BluesHarmonica.com recommends...
V1 = 12AY7
V2 = 12AT7
V3 = 12AU7
Greg Heumann on this forum recommends...
V1 = 12AX7
V2 = 12AU7
V3 = 12AU7
Deak Harp on this forum runs with...
V1 = 12AU7
V2 = 12AU7
V3 = 12AX7
My understanding is that it's better to have a higher gain tube in V1 as this is the first to pick up the signal and then drives the other tubes (have I got that right?). However I've also read that putting a low gain tube in the V3 increases the load on the amp and risk blowing out the resistors.
I realise that there are ideal mods for this amp involving speaker swaps and higher watt resistors etc but for now I'm just looking to make some tube swaps that will help tame feedback but still allow me to cut through a loud band. What do people recommend in this instance, given I don't want to risk damaging the amp?
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Greg Heumann
2243 posts
Jul 04, 2013
11:33 PM
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For the record, the 12AX 12AU 12Au is how most of the Sonny Jr amps are set up and they are pretty legendary. But you can't hurt the amp by trying all of the above. Either pick a name from above whom you trust and follow their recommendation, or try these all out for yourself. You won't hurt the amp.
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***************************************************
/Greg
BlowsMeAway Productions
See my Customer Mics album on Facebook
BlueState - my band
Bluestate on iTunes
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Harpaholic
268 posts
Jul 05, 2013
12:19 AM
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I wouldn't go lower than a 12AT in the PI (V3)
A 12AY may be ok but without beefing up the plate load resistors you risk the chance of damage to the resistors. I've seen it happen.
As far as V1 and V2 you can put in whatever you want in the 12AX family.
I prefer Dave's set up with a 12AT in the PI or a 5751 in V1.
I don't like cutting too much wattage and/or tone from any amp especially a big amp. If I remember correctly putting all 12AU's in a Cruncher drops the wattage to 16 watts.
Last Edited by Harpaholic on Jul 05, 2013 12:29 AM
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FMWoodeye
717 posts
Jul 05, 2013
6:46 AM
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Well, just for fun, I just switched to the Barrett configuration. I lean more toward Greg's advice, so I'll rummage around and see if I can find another 12AU and try that. I have the bass at 9, the middle at 6 and treble at 3, presence at 3, and I got to a light 6 (5.9) on the volume before feedback. I jumped channels, that is, ran a short cable from #1 bright to #2 normal and can now get a heavy 6 (6.2) on volume before feedback, or at feedback threshold. I jumped channels because...because...uh...I forgot (blush). The previous owner, a friend and harp player, recommended it and provided a short cable to do so. The previous configuration was 12AT7, 12AV7 and 12AU7 with feedback threshold at a heavy five.
Let me be clear that I would not presume to recommend to you what tubes to use. I'm merely experimenting with the recommendations above.
By the way, this is in my basement with a Front 'n Center mic on full, amp on casters, about three inches off the floor.
Last Edited by FMWoodeye on Jul 05, 2013 7:11 AM
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Rick Davis
2046 posts
Jul 05, 2013
6:58 AM
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I agree with Harpaholic. In my Bassman I think I tried every possible combination and permutation of preamp tubes, and the tube line-up I ended up with is 5751 - 5814a - 5751. The 5814a is a mil spec 12AU7. This keeps the amp lively and punchy but makes the gain a lot more manageble.
Yes, beef up the plate load resistors. The cheapo 1/4 watt carbon film resistors get stressed because the 12AU7 tubes draw more current, sometimes causing the little resistor to burn open. That leads to a nasty hum and could damage downstream components.
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-Little Rick Davis
The Blues Harp Amps Blog
The Mile High Blues Society
Tip Jar
Last Edited by Rick Davis on Jul 05, 2013 7:02 AM
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FMWoodeye
718 posts
Jul 05, 2013
7:04 AM
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Hey, Rick, I have a 5751 but only one. Would that be close to a 12AY? Maybe I'll try 5751, 12AU and 12AY. This is something I can do. Changing tubes is about as far as I'm going into this amp.
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Rick Davis
2047 posts
Jul 05, 2013
7:32 AM
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Woodeye, yep, the 12AY7 is a little less gain than the 5751. It should work great.
Note: Not all 5751 tubes are created equal. The ones I use are NOS JAN Philips tubes from Tube Depot for $35 each. In the Bassman I like them a lot better than the JJ Tesla 5751 tubes, which sound like a slightly de-tuned 12AX7.
But that is all just nibbling around the edges. Try swapping the 12AY7 and 5751 tubes in V1 and V3. If it sounds good it is good.
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-Little Rick Davis
The Blues Harp Amps Blog
The Mile High Blues Society
Tip Jar
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Rick Davis
2048 posts
Jul 05, 2013
7:42 AM
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Dave Kott at GreenBulletMics.com (a very good resource) uses 12AU7 in V1 and V2, with a 5751 in the phase inverter in his Bassman RI. I tried that and thought it calmed the amp a bit too much. Lots of players like a bit higher gain in V1 and I agree with them.
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-Little Rick Davis
The Blues Harp Amps Blog
The Mile High Blues Society
Tip Jar
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Kingley
2849 posts
Jul 05, 2013
8:20 AM
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In a Bassman LTD I like to use:
V1 = 12AY7
V2 = 12AX7
V3 = 12AX7
It sounds good with both CM/CR and Crystals that way and will cut through a fairly loud band. If I'm playing a lower volume gig then I like to use:
V1 = 12AY7
V2 = 12AX7
V3 = 12AU7
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Greg Heumann
2245 posts
Jul 05, 2013
8:22 AM
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Yeah - I don't like a 12AU in V1 - I think you want the one high gain tube there. In my experience, having given this advice to a lot of players, the most common mistake is people not going far enough. One of the reasons I like 12AX 12AU 12 AU is that you will really be able to feel the difference. If for any reason it is TOO MUCH (and it won't be) then you can ratchet the gain back up in either V2 or V3. If it is STILL not enough (and once in a while people tell me it wasn't - but it is rare) THEN work V1 down a little - 12AY or 5751 are both good choices.
Just my opinion but it has worked for me, and many others with a fairly wide variety of amps.
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***************************************************
/Greg
BlowsMeAway Productions
See my Customer Mics album on Facebook
BlueState - my band
Bluestate on iTunes
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1847
894 posts
Jul 05, 2013
10:19 AM
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just went to the local swap meet
picked up 5 au7's one dollar each!
1 raytheon
3 rca's and a ge
current set up
5814 double mica black plate
6072 triple mica black plate
6072 triple mica black plate
i agree with kingley witha aloud band
ay7
ax7
ax7 works great. with the kinder anti feed backer
some times 3 ax7's are the ticket.
i sometimes use a butler real tube pedal to add even more gain. with the kinder box i sometimes add a rat pedal to the mix. i turn down the distortion and the filter and crank the volume
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third times a charm!
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Harpaholic
269 posts
Jul 05, 2013
10:28 AM
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I too use Nos Jan 5751's (GE), and Rick's correct big difference from modern 5751's. I also have a bias pot that really helps to dial in the power tubes rectifier combo.
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FMWoodeye
719 posts
Jul 05, 2013
10:49 AM
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Well, I paid the lawn guy to carry the amp out to the garage. I've got 5751, 12AU7 and 12AY7. Feedback threshold is now 5.5, but it sounds pretty good. I will try jumping channels again, and I will try the LW Octave pedal just for fun, although the sound doesn't seem to need any help, but it may help to elevate the feedback threshold. I won't be able to go upstairs now for a while, though. The 5751 was made in Russia, purchased recently from Sweetwater.
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1847
895 posts
Jul 05, 2013
11:35 AM
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someone brought an lone wolf octave last sunday
very cool.... it definitely works well with the bassman
may have to get one of those myself
if i remember we went into the kinder first then the octave.
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third times a charm!
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1847
896 posts
Jul 05, 2013
11:36 AM
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oh and i have 7581a power tubes
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third times a charm!
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FMWoodeye
721 posts
Jul 05, 2013
12:54 PM
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Okay, I jumped the channels, and the feedback threshold went to 5.7 from 5.5. I put the mic through the LW Octave with the mix and volume both at 9:00 o'clock, and the feedback threshold moved from 5.7 to 7 flat.
So now I have sound, and I have volume. All I need now is a big...uh, I guess that's all I need.
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Adam Pritchard
10 posts
Jul 05, 2013
1:58 PM
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Thanks guys for you insights, patience and expertise. I'll experiment with a few different configurations. I'm thinking I'll have to stick with the higher gain tubes for now so as to ensure I can cut through the rest of the band but we'll see how it goes.
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