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Questions About The Schematics Of Diffrent Amps.


Daniel Sorbera
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Currectly I have no guitar amp.

Obviously I need to acquire one :D

I figured I'd build one. The ax84 P1 Extreme looks good for my style of music and seems very simple to build.

I was looking at it's schematic and the schematics of very good amps and comparing (bogner and the like)

and found that the ax84 design seemed maybe a little too simple. But than I found the Dr. Z mini-Z. I LOVE the sound of this amp. It's for me. But I don't have, and won't have in the near future, $700.

But what intrested me is the design is very very simple and yet it gets amazing tone. link

So I have two questions.

1. Does anyone have or know where I could get a schematic of the mini-Z?

2. In your opinion does the ax84 design sound good? (this is what I'm really wondering)

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Currectly I have no guitar amp.

So I have two questions.

1. Does anyone have or know where I could get a schematic of the mini-Z?

2. In your opinion does the ax84 design sound good? (this is what I'm really wondering)

question 1

you have a pic of the board here with all the parts.

Power Output: 5 watts

Output Tube: 1 - EL84

Preamp Tube: 1 - GT-12AX7M

Controls: Volume.

Configurations: 1-8 Combo

Colors: Black.

Dimensions and Weight: 13 1/2" W, 13 1/2" H, 9" D; 22 lbs

taken from dr z site above.

so 1 12ax7

1 el84

the resistors can be made out so asuming its not painted with fake values i would just make a schematic out of what you see.

personally [maybe i am wrong] I belive if you can't do a rough scheme of an amp this small of parts count based of the supplied info you shouldnt be building it [experience and such high voltage.]

but currently i am working on a scheme of it, i will let you know how it goes and i suggest you try for yourself.

thats how we all learned

ps this is said to be informative not as a slam

ciao

ed

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I was looking at it's schematic and the schematics of very good amps and comparing (bogner and the like)...
:D OK, now I'm confused - why would you compare the P1 EXtreme to a Bogner (or any other channel switching high-gain monster, for that matter)? Simplicity is no indicator of lower overall quality. If you're looking for cleaner tones to tweedy crunch, you probably won't do much better than the P1EX, but if you need more gain, the High Octane is going to be more your speed.

As for the Mini-Z, it's looks suspiciously like a 5E1 Fender Champ with the 6V6 replaced with an EL84 and a solid-state rectifier (and more than likely, no negative feedback), but it's been tweaked out by a true master, so even if you had the schematic, unless you could source the exact same output transformer and any other proprietary components, yours might sound quite different. You could always build the P1 (not the EXtreme, the original), and leave out the tone stack/master volume - that should get you into the ball park.

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That OT in the pic has numbers on it. Doesn't look like a "small run " custom OT to me.

Can anyone think of a reason why you couldn't make an amp like this, with a socket for an EL84 output tube, and then another socket for a 6V6 output tube. Either one of the output tube sockets would always be empty. Some pin lugs would be connected between the two sockets, and then each output tube socket would have it's own cathode resistor running to ground. I can't think of how the unused socket could cause a problem with the other socket being used, unless there's something I'm just not realizing when I think about it.

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but it's been tweaked out by a true master, so even if you had the schematic, unless you could source the exact same output transformer and any other proprietary components, yours might sound quite different.

This is why I think I'll just save up the money to buy one. I have no doubts I can make the circut, I just doubt it will sound as good as the original.

Simplicity is no indicator of lower overall quality.

Thats what I was confused about. I was just looking at random schematics of amps I know are good.

If you're looking for cleaner tones to tweedy crunch, you probably won't do much better than the P1EX,

Which is exatly the tone I'm going for.

it's looks suspiciously like a 5E1 Fender Champ with the 6V6 replaced with an EL84 and a solid-state rectifier (and more than likely, no negative feedback)

My thoughts exatly. I was going to build a champ (I was looking on ebay but they sell for $600+) But than I saw the mini-Z, and listened to the sound clips and liked it's tone also.

So what will I end up doing? I don't know. I think I would be happy with a P1, P1EX, Champ, or a Mini-Z.

I also know that I can build them all, and I can buy the champ or mini-z (for outrageoulsy high prices mind you)

I think I'll go with the P1EX so I can use all these sylvania and Tung Sol 6v6GT tubes I have sitting around.

Thanks for all the help guys.

Edited by Godin SD
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That OT in the pic has numbers on it. Doesn't look like a "small run " custom OT to me.

Can anyone think of a reason why you couldn't make an amp like this, with a socket for an EL84 output tube, and then another socket for a 6V6 output tube. Either one of the output tube sockets would always be empty. Some pin lugs would be connected between the two sockets, and then each output tube socket would have it's own cathode resistor running to ground. I can't think of how the unused socket could cause a problem with the other socket being used, unless there's something I'm just not realizing when I think about it.

No, no reason at all, assuming of course that the power transformer heater supply winding can handle the total heater current of whatever octal type tube you might want to stick in. After all, why limit yourself to a 6V6.

But if you're going to go this far, might as well splurge for a decent heavy duty switch to determine which socket's cathode resistor you want grounded. Without the cathode resistor tied to ground there will be no current flow through the tube. Selection via a switch is much easier than having to plug and unplug two tubes when you want to change.

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That OT in the pic has numbers on it. Doesn't look like a "small run " custom OT to me.

Great!! Now, just find us an inexpensive source for 'em (in qty. 1), and we can all build ourselves a cheap Mini-Z clone (if anybody wants to). :D FWIW, those numbers don't correspond to anything my suppliers carry. The good Doctor is notorious for using special Ken Fischer designed transformers to get his unique sounds, but I suppose this could just be a Fender transformer, or something similar.

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It'll sound as noisy and juicy as anything you'll build by hand

I don't get it, are you trying to cut me down or something? Or for some strange reason do you think all -good- tube amps hum like theirs no tomorrow?

If I did buy one of those, I would do mods to get rid of the noise. (do a search on google for valve junior mods)

Who knows, maybe I will just buy a valve junior. At just over $100 it seems like a good thing to buy and play around with.

Edited by Godin SD
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It'll sound as noisy and juicy as anything you'll build by hand

I don't get it, are you trying to cut me down or something? Or for some strange reason do you think all -good- tube amps hum like theirs no tomorrow?

If I did buy one of those, I would do mods to get rid of the noise. (do a search on google for valve junior mods)

Would you do mods on a mini-z to get rid of the noise?

The epi head has a DC filiment supply. I don't see that in the picture of the mini-z... but it might. I sure hope so because the filiment wires are not twisted as is normal practice with AC heater supplies.

The mini-z appears to be using carbon comp resistors in the signal path. Guess what the noisy-est resistors happen to be? The epi is more likely to be using at least carbon film and might even be using metal film since the prices are much cheaper now - both of which will be less noisy than carbon comp. Carbon comp has a hype factor going for them and that's about it.

But personally, I don't think that is what Crafty meant by "noisy".

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I'd be leery of building an amp without electronics experiance, you can easily be killed by the voltages in even a small 20 watt amp. If you want something cheap and easy to build with no risk of electric shock go over to www.runoffgroove.com and have a look at the Little Gem and Ruby schematics. They are tiny amps, only 1/2 watt to 1 watt but they have a great sound with the right speakers. Not something you can jam along with a drummer with but for sitting around your apartment you can get loud enough to annoy your neighbors. I built one with tone controls and a distortion channel, sounds great.

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Who knows, maybe I will just buy a valve junior. At just over $100 it seems like a good thing to buy and play around with.

I have heard very good things about the valve junior for the price.

As for the Mini Z - you can get one for less than $500 if you watch ebay. Also, you might want to look for a used Farben Bastage. You can also find them used for less the $500. I used to own one - they are a blast and you can swap a number of tubes in and out without having to rebias - EL84, EL34, 6V6, 6L6, blah blah. Ben Fargen makes great class A stuff.

Check out the clips on his web site:

Fargen BAstage Info

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i have played the epi, and man it smokes nice cabinet, i thought about just buying up some of them and modding them.

btw its a 4 ohm load fyi. just thought i would let you konw.

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The more I hear it the more I like the idea of buying a valve junior. I'll just try out the amp stock, than do some mods, and if I really hate it I'll just gut it and design a completely new amp and cram into the cabinet. $100 for a cabinet is a very good price :D

Edited by Godin SD
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It'll sound as noisy and juicy as anything you'll build by hand

I don't get it, are you trying to cut me down or something? Or for some strange reason do you think all -good- tube amps hum like theirs no tomorrow?

If I did buy one of those, I would do mods to get rid of the noise. (do a search on google for valve junior mods)

Who knows, maybe I will just buy a valve junior. At just over $100 it seems like a good thing to buy and play around with.

C'mon, G, when was the last time I cut you down? :D "Noisy" is a term of art--I should have written "character". But for $100, the Epi VJ will be a good head for you to play on and learn how to do simple mods to tube amps. Have fun wit it!

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thats about right. however you might want to check your transformer, mine only had the 4 ohm output and no other tap to make it 8 ohms.

also a 6v6 is a nice mod to it. i am hopefully getting mine out of storage this weekend.

[long story envolving repairs and former drug dealer/music store owner oweing me money]

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umm.. not wanting 2 take the piss, but have you tried a 10w BB Blaster? they are very low wattage but they seem 2 have quite a high output, i have 1 of them which i modded so it runs through 2 aiwa stereo cabinets and it works just loud enough to be heard over my friends drumkit. u get them for about £30 and they are very easy to mod :Dhttp://www.playrecord.net/bb-blaster-p-2711.html

have a look

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I got mine in the mail yesterday. Mine is the new one that has two cutouts in the back and the hum is not bad at all. When I put in an old, made in USA, sylvania 12AT7 the hum was reduced to "oh my god this is quiet" levels and it fattend up the tone considerably from the stock sovtek.

Mine does have an 8ohm tap (at least it says so on the transformer) But I havn't opened it up yet.

Eventually I will add master volume control and change the output tube to a 6v6 so I can use all these old Tung-Sol and Sylvania 6v6s I have sitting around.

Edited by Godin SD
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  • 2 weeks later...

Hey, check this out. I came across this pic of what's supposedly the guts of the new Gibson GA-5 amp, and unless my eyes are playing tricks on me, it has the same numbers on the OT as the Dr. Z amp photo linked in this thread.

http://i70.photobucket.com/albums/i115/teleamp/GA-5.jpg

I hope somebody can save the GA-5 photo, because I'm over-seas and might not be able to save it onto a disk.

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Hey, check this out. I came across this pic of what's supposedly the guts of the new Gibson GA-5 amp, and unless my eyes are playing tricks on me, it has the same numbers on the OT as the Dr. Z amp photo linked in this thread.

http://i70.photobucket.com/albums/i115/teleamp/GA-5.jpg

I hope somebody can save the GA-5 photo, because I'm over-seas and might not be able to save it onto a disk.

yes and yes its saved

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