Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Nathan on April 29, 2025, 08:39:29 am
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I found a good deal on a ~2004 tweed 410 combo with the blue alnicos. Why? Because I love bargains and always wanted a tweed amp. Really the Bassman has had my curiosity forever and there are many reviews saying this is a great sounding amp. There are some reports of reliability issues however and it's hard to control volume.
Johan seems to like his a lot:
https://youtu.be/9IIW9sXFXAs?feature=shared (https://youtu.be/9IIW9sXFXAs?feature=shared)
and
https://youtu.be/zGTghSXXCjo?feature=shared (https://youtu.be/zGTghSXXCjo?feature=shared)
This guy gets a much improved drive tone but doesn't indicate what the mods are:
https://youtu.be/HA1SBZZJIo4?feature=shared (https://youtu.be/HA1SBZZJIo4?feature=shared)
So what's your advice to mod this thing? My search turns up very little which makes me think it's not much loved around here?
Change master volume pot for audio taper?
Cheers!
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When you say hard to control volume do you mean its too loud even at low vol settings?
I have a tweed Pro Jr with 10" blue alnico and it is very loud at low settings (great little amp though)
What I have done is add a Lpad between speaker and amp which allows me to play ay higher vol settings getting drive without being too loud. The Lpad is a cheap way to do speaker soak. If this might be your issue you'll probably need 100w Lpad as my 50w Lpad gets warm with the 18w PJ. Audio taper better than linear.
This is Lpad (https://www.parts-express.com/L-Pad-100W-Mono-1-Shaft-8-Ohm-260-265?quantity=1&utm_source=google&utm_medium=cpc&utm_campaign=22349525447&gad_source=1&gbraid=0AAAAAD_wpb3GPsely18yUj1P4X-2dB_m5&gclid=Cj0KCQjw8cHABhC-ARIsAJnY12wH_dKEXOY16REtaBZc43MaXWR--5fQkJe6ZECun123k8j6JHmwRH4aAlgKEALw_wcB) like what I used
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This piques my curiosity (talk on the actual mod starts a about 4 mins)
https://m.youtube.com/watch?v=4tWenYyk2zE&pp=ygUHI2hvdG9kcw%3D%3D (https://m.youtube.com/watch?v=4tWenYyk2zE&pp=ygUHI2hvdG9kcw%3D%3D)
Another example of the same thing (Part 2 of this is out there somewhere)
https://m.youtube.com/watch?v=8ihZHnaYw6M (https://m.youtube.com/watch?v=8ihZHnaYw6M)
Where you buy the boards etc
https://luigiretro.com/HRD2ODS_retrofit_pcb (https://luigiretro.com/HRD2ODS_retrofit_pcb)
edit: I’ve been thinking lately that I would quite enjoy scoring one of these amps to gut for this mod.
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Another example of the same thing (Part 2 of this is out there somewhere)
https://m.youtube.com/watch?v=8ihZHnaYw6M (https://m.youtube.com/watch?v=8ihZHnaYw6M)
That guy's got a nose ring, can't watch that. :l2: :BangHead: :cussing:
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LoL
Here’s another one
https://upload.wikimedia.org/wikipedia/commons/9/93/Judas_Priest-30_%2852552165653%29.jpg (https://upload.wikimedia.org/wikipedia/commons/9/93/Judas_Priest-30_%2852552165653%29.jpg)
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These have the same low voltage supply problems as the Hot Rods, so expect problems with heat around the large ceramic resistors and zeners. These also have an IC buffered effects loop, so a simple 100k volume pot in the effects loop will act as a great master volume control.
I haven't much studied the switching on the schematic, but usual voicing tricks will apply, trim bass into drive gain stages, use of plate bypass caps to reduce fizz, etc.
How to mod it depends on what you want out of it that it currently isn't doing.
Also those blue alnicos are probably worth more on their own than you paid for the amp. Nice score.
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When you say hard to control volume do you mean its too loud even at low vol settings?
I have a tweed Pro Jr with 10" blue alnico and it is very loud at low settings (great little amp though)
What I have done is add a Lpad between speaker and amp which allows me to play ay higher vol settings getting drive without being too loud. The Lpad is a cheap way to do speaker soak. If this might be your issue you'll probably need 100w Lpad as my 50w Lpad gets warm with the 18w PJ. Audio taper better than linear.
This is Lpad (https://www.parts-express.com/L-Pad-100W-Mono-1-Shaft-8-Ohm-260-265?quantity=1&utm_source=google&utm_medium=cpc&utm_campaign=22349525447&gad_source=1&gbraid=0AAAAAD_wpb3GPsely18yUj1P4X-2dB_m5&gclid=Cj0KCQjw8cHABhC-ARIsAJnY12wH_dKEXOY16REtaBZc43MaXWR--5fQkJe6ZECun123k8j6JHmwRH4aAlgKEALw_wcB) like what I used
Funny I was aware of L-pads in hifi but we don't often see them used as attenuators in guitar amps.
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These have the same low voltage supply problems as the Hot Rods, so expect problems with heat around the large ceramic resistors and zeners. These also have an IC buffered effects loop, so a simple 100k volume pot in the effects loop will act as a great master volume control.
I haven't much studied the switching on the schematic, but usual voicing tricks will apply, trim bass into drive gain stages, use of plate bypass caps to reduce fizz, etc.
How to mod it depends on what you want out of it that it currently isn't doing.
Also those blue alnicos are probably worth more on their own than you paid for the amp. Nice score.
Yea, I saw the Dr. Watson Lion Tamer module. I would make my own but I do like the plastic housing with the plugs incorporated. Still over priced and you are shorting the signal before the power tubes.
My main issue is the touchy volume control but why in the world is it so hard to find a snap-in 100kA pot???
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Yea, I saw the Dr. Watson Lion Tamer module. I would make my own but I do like the plastic housing with the plugs incorporated. Still over priced and you are shorting the signal before the power tubes.
Most volume controls can be described this way. Do you have issue with shunting the signal to ground in the buffered effects loop in this amp?
Any passive volume control (and active) will work. A passive volume pedal would be great too.
My main issue is the touchy volume control but why in the world is it so hard to find a snap-in 100kA pot???
This is fairly easy to find. CE Dist has them as do several other online vendors. I keep them in stock to replace the linear 100k pots on reissue reverb amps I service.
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Still over priced and you are shorting the signal before the power tubes.
Thats why you use the Lpad or a speaker soak which goes between speaker and amp.
A volume pedal goes before amp unless amp has an FX loop then after preamp typically. so you would be dependent on distortion pedals for your "drive tone".
Give the Lpad a try and let us know how it sounds; its a relatively cheap and easy mod.
BTW the Bugera PS1 (https://reverb.com/p/bugera-ps1-power-soak-100-watt-attenuator?hfid=89452857&utm_source=google&utm_medium=cpc&utm_campaign=20393455322&utm_content=campaignid=20393455322_adgroupid=156833164212_productpartitionid=1717076219420=merchantid=5583721154_productid=89452857_keyword=_device=c_adposition=_matchtype=_creative=666667115194&gad_source=1&gbraid=0AAAAADRxZYUr-wq6N8xNZGHQ4BtZRDheG&gclid=Cj0KCQjw8cHABhC-ARIsAJnY12wMeX9Ii9SuY7TBNfABUNzmO4LL2d9tauud5fkjaLxd5PD5L5N9ohYaAtIkEALw_wcB) is a decent low price speaker soak that I use. also has a high impedance output to feed the house board
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Thanks guys, I did find a log taper pot and ordered it. I am going to change out the filter caps and probably do the master volume on both channels as per Fromel:
https://fromelelectronics.dozuki.com/Guide/Installing+Blues+Deville+Reissue+Mods+Blues+DeVille+Reissue+mods+(July+2022)/30?lang=en (https://fromelelectronics.dozuki.com/Guide/Installing+Blues+Deville+Reissue+Mods+Blues+DeVille+Reissue+mods+(July+2022)/30?lang=en)
The effects loop is something I almost never use but I have reservations about adding stuff external to the amp for something so simple as volume control. I do have a volume knob on each of my guitars, so there is another solution if the audio taper doesn't float by boat.
L-pad is a very interesting option which I will look into sooner or later. It's affordable and promising. Thanks for all your input!
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I do have a volume knob on each of my guitars,
as a tech, non-musician, I'm always fascinated at the replies I get when I ask; "Can't you just adjust a guitars volume/TS, isn't that much easier than having to trip over cords and other band members to get to the amp??"
:icon_biggrin:
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What I've found with the hot rod series, is that some boards do a better job of accommodating mods than others.
Some are harder to work on, the traces will lift easier, the ribbon cables break easier, you can't remove the solder from the connections as easy.
Whether you could successfully mod a hot rod amp, especially by trial and error, would probably depend on which board you have.
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Yeah I found this thread from last year and my logic is the same; "nothing wrong with the amp, just want a fun project":
https://el34world.com/Forum/index.php?topic=31504.0 (https://el34world.com/Forum/index.php?topic=31504.0)
Now I can't stop thinking about fully hand-wiring something cool. Rob Robinette has loads of mods to the 5F6A. I'd keep the control layout but kind of wish I could put a tube rectifier in. But alas, no 5V tap on the PT... Any workaround for that without buying a new PT?
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wish I could put a tube rectifier in. But alas, no 5V tap on the PT... Any workaround for that without buying a new PT?
Install a PT with a 5VAC secondary (or a small 5VAC PT)
Did you check out the dumbley rebuild?
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Yes I did. The only thing I know about the Dumble sound is that Robben Ford is a frequent user and I'm not a fan. I hear plenty of other users, but don't know which recordings.
All this to say that I don't want to go in that direction since I know the bassman sound and want to stay closer to that for this project.
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Not only Robben Ford - it’s a very versatile amp Have a listen to this by Larry Carlton
https://youtu.be/KnrFczrKd-Y (https://youtu.be/KnrFczrKd-Y)
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Joe Bonamassa plays Lowell George Dumble
and another
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SRV had 1, so did the great lap steel player David Lindly. He played the slide on Jackson Brown albums.