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#1
just bought this EVEREADY SKY QUEEN valve/tube radio, would like to turn it into a guitar amp, where do i start, i'm a complete newbie at this so any help woud be appreciated,



#2
1. Do you have any experience at all working with tube amps?

2. What kind of tubes are in there?

3. Do you have a schematic?
#3
Quick! Someone call Cathbard!
Quote by JD Close
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#4
Quote by Culler Amps
1. Do you have any experience at all working with tube amps?

2. What kind of tubes are in there?

3. Do you have a schematic?


no experience at all with valve amp's, but i am an electrician, so i know not to just power it up and then start sticking my finger's in amongst it,

tube's are DK96, DF96, DAF96, DL96,

no schematic yet, i'm still looking for one,,
#6
Cath is an amp builder rounf these parts, but Flightless is probably more interested to be honest he does this sort of thing a lot
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#7
Quote by GARAGE HERMIT
no experience at all with valve amp's, but i am an electrician, so i know not to just power it up and then start sticking my finger's in amongst it,

tube's are DK96, DF96, DAF96, DL96,

no schematic yet, i'm still looking for one,,



Most of these older radios were handwired point to point, and they really crammed that stuff in there on some radios. It could be a bit daunting for someone new to figure out what is going on in there.

Personally I'd gut the chassis, and start from scratch. For someone just getting into this hobby, I think you'd have a better chance of building a working, good sounding amp if you worked from an existing design.

Maybe build a champ style circuit in there.

Hopefully you can read a schematic.

If you are indeed completely new to this, I recommend going over to AX84 and thinking about building one of the projects over there. A great way to learn and get started.
#8
Quote by GABarrie
Cath is an amp builder rounf these parts, but Flightless is probably more interested to be honest he does this sort of thing a lot


Hey, that's me. I guess I can try to help you out here.

First off, check my signature for the basics of tube electronics when it comes to guitar audio. There are some good links in that thread as well.

Second, here is a great resource to find the tube data for about any tube there is:
http://tdsl.duncanamps.com/tubesearch.php Be sure to check at the bottom for actual data sheets since the website's info is often incomplete.

Most likely, you're going to want to completely remove the receiving part of the circuit. I don't have a schematic for your radio either, but here's a pretty standard receiving circuit: http://www.next.gr/uploads/15-7f5594e81c.gif

The DK96 is a heptode and you're going to not want to use this one at all. The DL96 is your output pentode most likely in a single-ended cathode biased output circuit. The DAF96 and DF96 are both candidates to use for your preamp tube. Several old Gibson amps as well as the Matchless DC30 used a single pentode as the preamp stage. Although the electrical characteristics of the DFs might make them less suitable for guitar frequencies.

This particular Valve Wizard page would be a good thing to read for your preamp stage: http://www.freewebs.com/valvewizard/pentode.html

I'm sure there is a lot more that could be said to help you out, but we'll see where you have questions first.
#9
ooop's, listed the wrong valve's, the actual one's in the set are,

6516ND/CV4063 KB/DC
6AT6
6064NJ/CV4014 KB/D
6AM6KJ/CV138 KB/D
and one with no writing on at all,
#10
Quote by end_citizen
Hey, that's me. I guess I can try to help you out here.

First off, check my signature for the basics of tube electronics when it comes to guitar audio. There are some good links in that thread as well.

Second, here is a great resource to find the tube data for about any tube there is:
http://tdsl.duncanamps.com/tubesearch.php Be sure to check at the bottom for actual data sheets since the website's info is often incomplete.

Most likely, you're going to want to completely remove the receiving part of the circuit. I don't have a schematic for your radio either, but here's a pretty standard receiving circuit: http://www.next.gr/uploads/15-7f5594e81c.gif

The DK96 is a heptode and you're going to not want to use this one at all. The DL96 is your output pentode most likely in a single-ended cathode biased output circuit. The DAF96 and DF96 are both candidates to use for your preamp tube. Several old Gibson amps as well as the Matchless DC30 used a single pentode as the preamp stage. Although the electrical characteristics of the DFs might make them less suitable for guitar frequencies.

This particular Valve Wizard page would be a good thing to read for your preamp stage: http://www.freewebs.com/valvewizard/pentode.html

I'm sure there is a lot more that could be said to help you out, but we'll see where you have questions first.


thank's for the link's, and i'm sure to have lot's more question's,
#11
Quote by GARAGE HERMIT
just bought this EVEREADY SKY QUEEN valve/tube radio, would like to turn it into a guitar amp, where do i start, i'm a complete newbie at this so any help woud be


I feel compelled to go out on a limb here and also at least commend those trying to provide helpful advice.

Personally I'd rather restore the radio if it was mine. You could have saved the money towards an amp if you needed one or a kit if you're looking to learn.
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#12
No offense intended, but isn't it really worth a lot more as a working radio?

It looks collectible, even from a sentimental perspective.

Besides most of the circuitry has virtually nothing to do with amplification, it's mostly front end for the tuner.

You still would have to design the tone control and pregain stages. And it's doubtful if the radio has a heck of a lot more that 1 watt of power anyway.

I'd really just clean it up, then find a special place for it on a bookshelf. It's more or less what I'd call, "a conversation piece"

It'd be way better to mock up a whole new box using the radio's exterior design, then build a tube amp to go in that. You could even modify the size, and just keep the overall shape, to accommodate a larger speaker, better cooling, etc.
Last edited by Captaincranky at Jul 30, 2012,
#13
Quote by end_citizen
Hey, that's me. I guess I can try to help you out here.

First off, check my signature for the basics of tube electronics when it comes to guitar audio. There are some good links in that thread as well.

Second, here is a great resource to find the tube data for about any tube there is:
http://tdsl.duncanamps.com/tubesearch.php Be sure to check at the bottom for actual data sheets since the website's info is often incomplete.

Most likely, you're going to want to completely remove the receiving part of the circuit. I don't have a schematic for your radio either, but here's a pretty standard receiving circuit: http://www.next.gr/uploads/15-7f5594e81c.gif

The DK96 is a heptode and you're going to not want to use this one at all. The DL96 is your output pentode most likely in a single-ended cathode biased output circuit. The DAF96 and DF96 are both candidates to use for your preamp tube. Several old Gibson amps as well as the Matchless DC30 used a single pentode as the preamp stage. Although the electrical characteristics of the DFs might make them less suitable for guitar frequencies.

This particular Valve Wizard page would be a good thing to read for your preamp stage: http://www.freewebs.com/valvewizard/pentode.html

I'm sure there is a lot more that could be said to help you out, but we'll see where you have questions first.
It is indeed you, I don't actually know your name and flightless is cooler than end_citizen Merlin's site should be moving within the next month btw
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#14
Quote by Phoenix V
I feel compelled to go out on a limb here and also at least commend those trying to provide helpful advice.

Personally I'd rather restore the radio if it was mine. You could have saved the money towards an amp if you needed one or a kit if you're looking to learn.


thanks for your input, but over here these radio's are cheap, this one was only £5.00, and for it to be a collectable one would have to be in a lot better condition than this one, i have a valve amp, a epiphone electar, amp kit's are i think too expensive, especially as i have bought several old valve reel to reel tape machine's, valve record player's, and a few valve radiogram's, plus a few more valve radio's all for less than £50.00 to practice on, i think i'll learn more about valve amp building trying to convert these than a kit, and i appreciate everyone's comment's,
#15
Quote by Captaincranky
No offense intended, but isn't it really worth a lot more as a working radio?

It looks collectible, even from a sentimental perspective.

Besides most of the circuitry has virtually nothing to do with amplification, it's mostly front end for the tuner.

You still would have to design the tone control and pregain stages. And it's doubtful if the radio has a heck of a lot more that 1 watt of power anyway.

I'd really just clean it up, then find a special place for it on a bookshelf. It's more or less what I'd call, "a conversation piece"

It'd be way better to mock up a whole new box using the radio's exterior design, then build a tube amp to go in that. You could even modify the size, and just keep the overall shape, to accommodate a larger speaker, better cooling, etc.


the radio was £5.00, and the condition it's in it is'nt collectable, 1 watt would be more than enough for what i want, thank's for your input,
#16
Quote by GARAGE HERMIT
thanks for your input, but over here these radio's are cheap, this one was only £5.00, and for it to be a collectable one would have to be in a lot better condition than this one, i have a valve amp, a epiphone electar, amp kit's are i think too expensive, especially as i have bought several old valve reel to reel tape machine's, valve record player's, and a few valve radiogram's, plus a few more valve radio's all for less than £50.00 to practice on, i think i'll learn more about valve amp building trying to convert these than a kit, and i appreciate everyone's comment's,


Well it's yours to do what you want. Was just saying if it was mine Id be reluctant to butcher it.

As a beginner I still believe a kit is a better way of cutting your teeth into this. Kits use stock readily available components, come with schematics and the build information. As you learn how the circuits work you can also mod and customise various things like the tonestacks or running bias, etc

Anyway, you'll need to get a schematic before you can get too far into it. Failing that, you'll have to accurately trace the circuit by hand and eye to generate the schematic as the audio section would be one of 4 main blocks in the circuit and there is also some overlap between blocks and feedback loops youll need to overcome.
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#17
been reading a bit about valve amp's and came up with this circuit, it's all probably wrong, cap value's etc, if someone can correct it for me, i'd be very greatfull,



#18
Curious: Why did you tie the two preamp grids together?

Also, assuming you don't want the two preamp tube grids tied, you'll want a 1M resistor after the 47k input resistor as a ground reference.

Another: Why do you have diodes on your tube rectifier?
#19
I believe wiring the anode to the grid like that will fry some tubes in a hurry... correct me if I'm wrong, but wouldn't that be an oscillator? I've converted an AA5 radio into an amp, people said it couldn't be done/wasn't worth it but I did it anyhow. It was great for practicing when I was in a dorm. But now I'm back home and I haven't run it since...
#20
Quote by end_citizen
Curious: Why did you tie the two preamp grids together?

Also, assuming you don't want the two preamp tube grids tied, you'll want a 1M resistor after the 47k input resistor as a ground reference.

Another: Why do you have diodes on your tube rectifier?


diode's (1N4007) are ther to protect the PT in case the rec/tube short's out,

yes, i will need a 1M resistor, thanks for that,

i'm using 2 x 6AT6's in parallel instead of a 12AX7, so i thought i'd parallel everything out, is that wrong, ??
#21
Quote by LeviMan_2001
I believe wiring the anode to the grid like that will fry some tubes in a hurry... correct me if I'm wrong, but wouldn't that be an oscillator? I've converted an AA5 radio into an amp, people said it couldn't be done/wasn't worth it but I did it anyhow. It was great for practicing when I was in a dorm. But now I'm back home and I haven't run it since...


you mean on the EL84, ? if the link from the anode to the grid is'nt needed, i wont put it in,

i'm a newbie at this tube stuff, dont forget, so i need all the help i can get, i just picked different bit's and piece's from different circuit drawing's and came up with this circuit, i'm using the two 6AT6's instead of a 12AX7 as i have them, so i've just paralled them up, will this be ok, ?? , thank's,
#22
Gotcha on the diodes. Just making sure it had a purpose and you didn't think that tube rectifiers needed diodes for some reason.

The way you have it running is not parallel. Most 12ax7s aren't run in parallel (with the exception of almost every Matchless amp). Give me a second and I'll draw up a parallel vs cascaded circuit.
#23
Quote by end_citizen
Gotcha on the diodes. Just making sure it had a purpose and you didn't think that tube rectifiers needed diodes for some reason.

The way you have it running is not parallel. Most 12ax7s aren't run in parallel (with the exception of almost every Matchless amp). Give me a second and I'll draw up a parallel vs cascaded circuit.


the two 6AT6's are taking the place of one 12AX7,
a 6AT6 is half a 12AX7, that's why they are in parallel, or have i wired the 6AT6's wrong,
#24
Here is a basic comparison of cascaded vs parallel.


I'm not sure where he is saying you have a grid tied to an anode.

EDIT:
Quote by GARAGE HERMIT
the two 6AT6's are taking the place of one 12AX7,
a 6AT6 is half a 12AX7, that's why they are in parallel, or have i wired the 6AT6's wrong,


You indeed have them wrong. You have them as if you want them both cascaded and paralleled.
Last edited by end_citizen at Sep 26, 2012,
#25
Quote by end_citizen


I'm not sure where he is saying you have a grid tied to an anode.



he's talking about the EL84, where i have the grid linked to the CATHODE,
#26
Quote by end_citizen


EDIT:

You indeed have them wrong. You have them as if you want them both cascaded and paralleled.



ooop's, i'll have to draw it out again, and see if i can get it right, thank's,
#27
Quote by GARAGE HERMIT
he's talking about the EL84, where i have the grid linked to the CATHODE,


That is the suppressor grid, and it is supposed to be tied to the cathode.

This is for the sake of the tube, but not necessary if you aren't too concerned about tube life: You'll probably want to put in a screen resistor (1k 5w resistor going between High Voltage and the screen grid).
#28
Quote by end_citizen
That is the suppressor grid, and it is supposed to be tied to the cathode.

This is for the sake of the tube, but not necessary if you aren't too concerned about tube life: You'll probably want to put in a screen resistor (1k 5w resistor going between High Voltage and the screen grid).


so on the EL84 pinout's i'll put the 1k-5w resistor onto pin's 1 and 8, ?
#29
On an EL84, Pins 1 and 8 aren't connected to anything. Here's the pinout (NC=Not Connected):

1: NC
2:Control Grid (Input)
3: Cathode AND Suppressor Grid (You don't have an option. They are always tied together)
4: Heater
5: Heater
6: NC
7: Plate/Anode (Output)
8: NC
9: Screen Grid (Put 1K resistor here)

EDIT: It appears you are using a EL34 pinout, not EL84
Last edited by end_citizen at Sep 26, 2012,
#31
drew another schematic, for paralleling up the 6AT6's, not too sure this one's right either, anyone see any mistake's, please let me know,,

Last edited by GARAGE HERMIT at Oct 2, 2012,
#32
I'm still wondering why you want the 6AT6s in parallel. You'll get more volume and gain out of cascaded gain stages. Also, your volume control is certainly not right.

I'd do the preamp more like this (feel free to leave out the tonestack):


The output section looks fine to me. The power supply looks sufficient. The 100k dropping resistor might be a little too high, but that can be fixed later on.

If you want to keep the preamp paralleled, get rid of the capacitor going to the volume control. Move the volume control to where the 330k resistor is going between ground and the EL84 control grid.
#33
end citizen,
thank's for the schematic, i did'nt know cascad'ed would be better than parallel, i'll do another schematic and see what you think of it,
looking forward to getting the soldering iron out,
#34
here's the Mk3 drawing, hope i'm getting somewhere near to getting it right, lol,

i've read that a grid stopper resistor on the EL84 would be a good idea, would that go on pinout No9 or No2,?

#35
Cursory glance at the schematic, preamp is looking good. If you find it has too much gain when you've built it, take out one or both of the 25uF/25v caps on the cathodes. That's for you decide.

Output section: It would work, but you should put the 1K/5w resistor going to the screen back in (Screen resistor). This will improve tube life. (Pin 9)

As for grid resistor, it isn't a bad idea. It prevents unwanted interference from stray capacitance and radio signals. Although that late in the circuit, it isn't a huge problem. Anywhere from 2.2k to 22k should be sufficient, although higher resistance will equal less highs. (Pin 2)
#36
another senior moment, forgot to put the 1k/5w resistor in the schematic,

so you think i'm all ok to start soldering,?

really appreciate your help with this,
#38
Quote by GARAGE HERMIT
another senior moment, forgot to put the 1k/5w resistor in the schematic,

so you think i'm all ok to start soldering,?

really appreciate your help with this,


Looks like you're probably good to go. If you come across any problems, I'd be glad to help out.
#39
just ordered all the resistor's and capacitor's off ebay, but there were a few value's i could'nt find so i ordered the nearest to them,

capacitor's,
20uf/400v wanted,, ordered 22uf/400v
25uf/25v wanted,, ordered 22uf/63v

resistor's,
1k/5watt wanted,, ordered 1k/3watt,

would these value's still work ok, ?
#40
Those should all work. The 1k/5w might be a little bit stronger than needed on an EL84. So, 3W should be fine.

The tolerance on a capacitor is usually about -10%/+20%. So, there is a good chance the values you ordered are pretty close to what you designed.
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