Bare Knuckle Pickups Forum
Forum Ringside => Guitars, Amps and Effects => Topic started by: MrBump on August 19, 2008, 09:13:06 AM
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Anyone seen these?
http://www.axiomatic-music.co.uk/acatalog/MOJOTONE_AMPLIFIER_KITS.html (http://www.axiomatic-music.co.uk/acatalog/MOJOTONE_AMPLIFIER_KITS.html)
Look quite interesting...
Mark.
EDIT - actually, they're quite pricey...
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i got an email and had a look yesterday... the courses make it quite interesting though - but yeah, definately pricey
i noticed they were available from allparts as well
http://www.allparts.uk.com/Allparts-building-courses-c-550.html
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They're Tube Amp Doctor kits by the look of it.....
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They seem to be WAY more expensive than the Ceriatone ones...
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They are.
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i thought they were mojo tone - just as expensive in the states
http://www.mojomusicalsupply.com/products.asp?id=44991
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These kits look far better value:-
http://www.astonelectronics.co.uk/
I think somebody on the forum built one of these recently, hopefully they will chip in with a review.....
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To be honest there isn't really much difference in price between these kits once import duty and components are taken into consideration. For example the cab (a Tweed covered cab will be more expensive than a Tolex covered) and chassis (chrome plated + silkscreened) in a Tweed Mojotone kit is inherently more expensive than a bare metal chassis a la Astonelectronics. Additionally transformer quality (and hence price) can vary considerably. Building your own amp is often less cost effective than buying one.
As ever you get what you pay for......
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i think the weber ones look pretty good in terms of price, the size if the range and the amount of options you have for each model... also a EU transformer does not cost extra
https://taweber.powweb.com/store/kits.htm
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Yeah have built an aston kit..easy clear instructions even for a novice like me with schematics and pics of where everything goes and backup on the phone if it goes wrong..forgot to add also asked for mod to kit to have it 6v6 instead of el84...no prob..and great sounding amp
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To be honest there isn't really much difference in price between these kits once import duty and components are taken into consideration. For example the cab (a Tweed covered cab will be more expensive than a Tolex covered) and chassis (chrome plated + silkscreened) in a Tweed Mojotone kit is inherently more expensive than a bare metal chassis a la Astonelectronics. Additionally transformer quality (and hence price) can vary considerably. Building your own amp is often less cost effective than buying one.
As ever you get what you pay for......
Well you do get what you pay for but you can see the attraction of building, say, the kit sgmypod has built against buying something like a Victoria 5F1. It might not have the right tweed, chrome plated chassis or cabinet i.e. visual vibe, but presuming (and I have no reason to believe otherwise) that Aston supply well speced Transformers etc the cost difference is massive. You could make a flat-packed solid pine cabinet, put in a Celestion Blue and still have £400 change.
The upcharge for such things as carbon comp resistors and orange drop caps would be minimal.
Assuming the Aston kit is based on the 5F1, would they actually sound much different?
Or would the aston sound better because of the bigger cabinet and better speaker?
I'm not saying kits are answer for everybody, but if you can solder, and are not to fussy about aesthetics and want a simple circuit vintage design, then they look excellent value. Plus you get something out of building the thing....
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The courses are being run by John Dickinson - a friend of mine, up at his studio/workshops in Crystal Palace
I'm keen to do one , although I even keener to the the Egnater course - but that is in Detroit
http://www.youtube.com/watch?v=sBrdbWdNrJw&feature=related (http://www.youtube.com/watch?v=sBrdbWdNrJw&feature=related)
http://www.youtube.com/watch?v=8QY3gfxTfTw&feature=related (http://www.youtube.com/watch?v=8QY3gfxTfTw&feature=related)
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[/quote]
Well you do get what you pay for but you can see the attraction of building, say, the kit sgmypod has built against buying something like a Victoria 5F1. It might not have the right tweed, chrome plated chassis or cabinet i.e. visual vibe, but presuming (and I have no reason to believe otherwise) that Aston supply well speced Transformers etc the cost difference is massive. You could make a flat-packed solid pine cabinet, put in a Celestion Blue and still have £400 change.
The upcharge for such things as carbon comp resistors and orange drop caps would be minimal.
Assuming the Aston kit is based on the 5F1, would they actually sound much different?
Or would the aston sound better because of the bigger cabinet and better speaker?
I'm not saying kits are answer for everybody, but if you can solder, and are not to fussy about aesthetics and want a simple circuit vintage design, then they look excellent value. Plus you get something out of building the thing....
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Absolutely. You can save a lot of money by making your own cabs etc, however I expect many people don't have the tools/ space or expertise to do this. The main pain for me when building an amp is punching the chassis. The novelty of making nice round holes using a chassis punch soon wares off! Also having a proper panel gives the amp a nice pro finish.
I can't really comment on the quality of the transformers used in the Aston Electronics kits as I haven't seen them. What I will say is that there are many factors that add significantly to the cost of manufacturing a transformer that aren't always apparent in the final product. Regardless their kits look very good value.
The Aston Electronics 5W amp has tone controls and uses an EL84 output valve, so won't sound like a Tweed Champ, although I'm sure you could build a Tweed Champ by modifying the kit.
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Yeah, it would have to be pre-punched all the way for me :)
I think sgmypods was the 6v6 version which is basically a champ with tone control.
I agree about the Transformers, often overlooked but one of the secrets to good tone. That's why Mercury Magnetics do so well!
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Yeah mine is a 6v6 so modified circuit..to orig kit but champ like master vol, vol tone......bought top to make it look like a birdcage, then bought a flat pack cab....turned on head, routed for controls..now a combo
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Sounds like a good project.
It's great you can get flat packed cabs as this takes out the heavier woodwork.
There is no tone control on a Tweed Champ. I suspect your circuit is nearer a Tweed Princeton, which is a very cool amp too! You can always add a switch to disable the tone control which will give you more gain.
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Just had a listen to a princeton..yeah mine ain't far off that sound have a jensen c12k with it
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i did a champ kit from Stf-electronics a few years ago that i thought was pretty good for the money and had great instructions - i did that before i had even done a BYOC kit. I added a tone control and master volume to it as well
took a while to arrive though
i never realised how good it actually sounded because i built it with an 8" ceramic speaker but hooked it up to my dual greenback cab before i got my little rock and it did make me wonder if i needed the matamp... till the matamp turned up.
http://www.stf-electronics.com/
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Sounds like a good project.
It's great you can get flat packed cabs as this takes out the heavier woodwork.
There is no tone control on a Tweed Champ. I suspect your circuit is nearer a Tweed Princeton, which is a very cool amp too! You can always add a switch to disable the tone control which will give you more gain.
Would that work like the 'E.Q cut switch' on a Cornell Romany? It's nice to have the versatility of a tone control but it would also be good to go back to vintage mode if required. Sounds like a good idea!
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Indeed it would (and by co-incidence I was working on a Cornell Romany at the weekend).
If you lift the ground from the bottom of the tone control you will disable it. In practice it is better to tie a large value resistor (say 10 M) between the bottom of the tone control and ground and arrange a switch to short this out to enable the tone control. This will avoid any loud pops due to DC level shift.
Re Speakers for Champs, I agree you can often get a better tone through a larger speaker, although a decent 8" speaker records really well. All Champs, and most Champ copies though only have an 4 ohm tap on the output transformer. I've seen plenty of Champs with repro 8 Ohm speakers in them (I've got one in the work shop at the moment). This generally doesn't sound that great.
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Indeed it would (and by co-incidence I was working on a Cornell Romany at the weekend).
If you lift the ground from the bottom of the tone control you will disable it. In practice it is better to tie a large value resistor (say 10 M) between the bottom of the tone control and ground and arrange a switch to short this out to enable the tone control. This will avoid any loud pops due to DC level shift.
Would that result in a gain increase then like on the Romany or is there something else happening on that
I have a Cornell Stinger - the precursor of the Romany and it works pretty much the same- all except it doesn't have the reduced power switching
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i have nothing against 8" speakers but i did skimp on that bit. i built the stf with a 4-ohm tap but i think there was the option of adding other outputs
i have my 2x12 8ohm speaker cab wired with a series/parallel switch which i hope gives me the option of 4 or 16 ohms. 4 for the champ kit, 16 for the little rock... hopefully
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Indeed it would (and by co-incidence I was working on a Cornell Romany at the weekend).
If you lift the ground from the bottom of the tone control you will disable it. In practice it is better to tie a large value resistor (say 10 M) between the bottom of the tone control and ground and arrange a switch to short this out to enable the tone control. This will avoid any loud pops due to DC level shift.
Would that result in a gain increase then like on the Romany or is there something else happening on that
I have a Cornell Stinger - the precursor of the Romany and it works pretty much the same- all except it doesn't have the reduced power switching
All passive tone controls load down the signal (usually referred to as insertion loss) by shunting signal to ground. By lifting the ground you disable the tone controls and thus giving an apparent increase in gain, although in reality you actually have less loss.
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This is an inside shot of mine....although tidied up a bit inside since
(http://a387.ac-images.myspacecdn.com/images01/80/l_9d8038e835df85112c7db73eee36346a.jpg)
And how its wired
(http://a248.ac-images.myspacecdn.com/images01/45/l_d2ce9c863514560fd840b2d7bc4a7527.jpg)
I have one question..could I make the single tone control..either have a larger range or is it possible to have a bass and treble seperatly controlled
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Indeed it would (and by co-incidence I was working on a Cornell Romany at the weekend).
If you lift the ground from the bottom of the tone control you will disable it. In practice it is better to tie a large value resistor (say 10 M) between the bottom of the tone control and ground and arrange a switch to short this out to enable the tone control. This will avoid any loud pops due to DC level shift.
Re Speakers for Champs, I agree you can often get a better tone through a larger speaker, although a decent 8" speaker records really well. All Champs, and most Champ copies though only have an 4 ohm tap on the output transformer. I've seen plenty of Champs with repro 8 Ohm speakers in them (I've got one in the work shop at the moment). This generally doesn't sound that great.
How come they don’t sound as good with an 8ohm tap/speaker? I was hoping to try a Celestion blue. I was thinking that the increased sensitivity of the bigger driver, coupled with the sweetness of the fabled Alnico speaker would give a match for some great fenderish cleans.
Perhaps that’s why you don’t see champs with 12 inch cones. Is it a limitation of the circuit, the transformer or just that the champ circuit suits and 8inch driver?
If this is the case I’m presuming a Jensen P8R or C8R would be the best choice?
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Indeed it would (and by co-incidence I was working on a Cornell Romany at the weekend).
If you lift the ground from the bottom of the tone control you will disable it. In practice it is better to tie a large value resistor (say 10 M) between the bottom of the tone control and ground and arrange a switch to short this out to enable the tone control. This will avoid any loud pops due to DC level shift.
Re Speakers for Champs, I agree you can often get a better tone through a larger speaker, although a decent 8" speaker records really well. All Champs, and most Champ copies though only have an 4 ohm tap on the output transformer. I've seen plenty of Champs with repro 8 Ohm speakers in them (I've got one in the work shop at the moment). This generally doesn't sound that great.
How come they don’t sound as good with an 8ohm tap/speaker? I was hoping to try a Celestion blue. I was thinking that the increased sensitivity of the bigger driver, coupled with the sweetness of the fabled Alnico speaker would give a match for some great fenderish cleans.
Perhaps that’s why you don’t see champs with 12 inch cones. Is it a limitation of the circuit, the transformer or just that the champ circuit suits and 8inch driver?
If this is the case I’m presuming a Jensen P8R or C8R would be the best choice?
If the transformer has an 8 ohm tap then that will work fine. However if you have a repro replacement transformer will only have a 4 ohm tap, like the original Champ OT, so you really need a 4 ohm load. A 12" speaker won't fit in a Champ, although I've see Champs that have had 10" speakers put in them. I would not advise doing this to a vintage Fender amp!!
Re speakers, I would not recommend the Jensen speakers — I'm not a huge fan to be honest. If you want an 8" 4 ohm speaker your best bet is getting a Mojotone or Weber (they are the same speaker) from Allparts UK. These sound really good, and are the same price as the Jensen.
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This is an inside shot of mine....although tidied up a bit inside since
(http://a387.ac-images.myspacecdn.com/images01/80/l_9d8038e835df85112c7db73eee36346a.jpg)
And how its wired
(http://a248.ac-images.myspacecdn.com/images01/45/l_d2ce9c863514560fd840b2d7bc4a7527.jpg)
I have one question..could I make the single tone control..either have a larger range or is it possible to have a bass and treble seperatly controlled
You can vary the range of the tone control by changing the value of the cap conected to ground from the bottom to the tone pot. High values will cause more mid frequencies to ground and lower values will cause less mid being bled to ground. You can wire in treble + bass controls, and there are tons of circuits on the web for these. You will get more insertion loss though with this type of control when compared to a simple tone control though.
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Ok so if I wanted a little more bass (I know am a heathen to add more bass to a this champ style of amp) what would I change the 0.0047 to
Also like the tone removal idea...so would need a 10m resistor...what w rating
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Ok so if I wanted a little more bass (I know am a heathen to add more bass to a this champ style of amp) what would I change the 0.0047 to
Also like the tone removal idea...so would need a 10m resistor...what w rating
You can't really boost bass by altering the tone control, you can only cut less bass. Experiment with small caps, say 0.0022 to start with.
You could also try increasing the size of the cap on the cathode of the second valve stage. I can't read the value (I suspect it is 0.68 µF) but it is the polystyrene cap second from the right in your photo. Try up to 20 µF.
You could also try increasing the value of the coupling caps, although without knowing their values (I can't read values on the schematic), then I can't advise whether this will help or not.
To disable the tone control connect a 10 M resistor between ground an the 0.0047 cap. Then wire a switch to short out the 10 M resistor. Any 10 M resistor will do — to dissipate 0.25 W in a 10 M resistor would require 1.5 kV across it!!
A word of caution though too much bass and you might encounter the dreaded blocking distortion.
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Ok...have sent an email..easier to read schematic....thanks for the help
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"I've seen plenty of Champs with repro 8 Ohm speakers in them (I've got one in the work shop at the moment). This generally doesn't sound that great."
So this is because they are using a 4 ohm tap with an 8 ohm speaker? They sound bad because of the mismatch?
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Yes. In my opinion the mismatch doesn't help, and you will definitely lose power.
Now we are lucky are plenty of decent 4 ohm 8" speakers for guitar amps out there, however in the past is suspect that if you blew your Champ speaker you used whatever you could find, which would probably be 8 ohm, cheap and nasty.
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a 12" speaker can transform the weediest of practice amps into something workable, even those Squier 15R combos sound passable through a 4x12 and my Epi VJ sounds very tasty with a crunchbox in the front into a 4x12.
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well tried Jpamps(thanks) idea of change of cap.....is a subtle change but give it a better sound to me, oh yeah mine is through a 1x12
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well tried Jpamps(thanks) idea of change of cap.....is a subtle change but give it a better sound to me, oh yeah mine is through a 1x12
The real fun's experimenting once you've built the amp.
I would concur with a 12" speaker and a larger box; I also really like 10" speakers.
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To be honest I do like 10inch speakers..but flat pack cab was a 1 x 12...may get changed later *L*
Oh yeah thanks again
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Yeah, I don't think bigger is always better, 10inch cones have a certain zing that 12's sometimes lack, certainly at lower powers. The new 10inch Celestion Alnico Gold looks good but it will probably be expensive.
I think over about 15watts though you start to need 1x12 or 2x10 to make full use of the amps power. I wouldn't put a 10 in a AC15 or '57 deluxe kind of amp. That's where I think the Laney LC15's suffer a bit. That and the cr@ppy cabinets and cheap transformers.
Rivera have now brought out their pubster with a 12inch driver which is about time, 25W into 1x10 is too much power IMO
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Yeah, I don't think bigger is always better, 10inch cones have a certain zing that 12's sometimes lack, certainly at lower powers. The new 10inch Celestion Alnico Gold looks good but it will probably be expensive.
I think over about 15watts though you start to need 1x12 or 2x10 to make full use of the amps power. I wouldn't put a 10 in a AC15 or '57 deluxe kind of amp. That's where I think the Laney LC15's suffer a bit. That and the cr@ppy cabinets and cheap transformers.
Rivera have now brought out their pubster with a 12inch driver which is about time, 25W into 1x10 is too much power IMO
I would tend to agree with this, which I probably why I am not a fan of 50W single 12" speaker combos. One of my favourite amps in the Fender BF Vibrolux which is 2 x10 and 35 Watts. 10" speakers seem to cut through a bit more.
I expect the 10" Celestion Gold will be the same price as a 12" Gold. The magnet, which is the same in both the 10 and 12" Golds, is the major expense in these speakers. I'm not sure though how useful a 45W 10" Alnico speaker is. Most 2 x 10 combos are 30-40 watts, and this will be overkill and v-v-v-v-very heavy in a 4 x 10 combo. I would have thought a smaller magnet/ smaller voice coil 25 W speaker would have been a much better bet. Celstion make virtually all their speakers on a 1.75" voice coil, I expect to save money as much as any thing, so perhaps they didn't want to invest in new tooling to do this.