5F1 head amp - layout

[johnlau]

Hi,

I have spent over 2 weeks time to study the resources from the internet for building a 5F1 head amp and have been ordering the required parts for the build.

I have just got the turret board done over the weekend and have received the 2 transformers today.

My plan is to build the head amp only and will get it connected to the speaker from my Marshall Valvestate 8020.

I will get my own chassis and I have been planning about the layout today. I am not sure whether my proposed layout would have any issues with the sound quality and would be very much appreciated if members here can offer their comments/advices.

Thanks.

[johnlau]

This is the chassis that I think I will buy for my build.

[keithb7]

Is it just me, or do those transformers look huge for a 5F1?

[tubeswell]

Hmmm... is that a SE OT? (Only it looks like its got three leads coming out of one side)

[gearjunkie]

look forward to seeing how it turns out,,keep us posted

[celeste]

The hardware layout should be good, but there are plenty more parts you can bozo the layout with.

keithb7, It is not just you
tubeswell, it has 4 wires, 2 out each side, look at the pic below.
Ernie R, Hammond makes cages for some of their chassis. http://angela.com/hammond1451seriess...orchassis.aspx

[JDO]

looks like a PP OT to me as well.

[tubeswell]

Originally Posted by celeste

tubeswell, it has 4 wires, 2 out each side, look at the pic below.

I counted two blue wires and a black wire on one side

[celeste]

Originally Posted by tubeswell

I counted two blue wires and a black wire on one side

Looks like a shadow to me, not that any of this matters

[johnlau]

the left one is the power transformer, the right one is the output transformer.
tubeswell: you counted it right, on the right hand side of the output transformer, there are three cables (0, 4 & 8 Ohm)
These transformers are made by factory in China (I sent the factory of the input/output ratings of these 2 transformers and the factory made them for me)

I am still planning about the layout. I have a small chassis, if I place the output transformer right about the PCB (in-between them is the aluminium made chassis cover, 2mm thick), would it be ok? Or I should not do that cause the currents generated from these 2 items may affect each other and may affect the sound quality?

Thanks.

[johnlau]

here is the component layout

The turret board will be undernearth the top panel

would it be ok or this chassis is too small to fit in everything?

[hackworth1]

As long as you have stand-offs, Your board can overlap the tube sockets inside if necessary.


By boothillamps at 2011-10-19

Tube sockets are hidden under the board.

[charisjapan]

Originally Posted by hackworth1

As long as you have stand-offs, Your board can overlap the tube sockets inside if necessary.


By boothillamps at 2011-10-19

Tube sockets are hidden under the board.

Not to sidetrack, but is that a Champ 600 Ri with a 5F1 p2p? If so, is that the original OT (and PT)? I've seen some pretty ugly p2p conversions, but that looks nice and tidy!

[muchxs]

Originally Posted by johnlau

here is the component layout

The turret board will be undernearth the top panel

would it be ok or this chassis is too small to fit in everything?

There are a couple thngs to consider.


The shortest distance between two points is usually the right way to do it. Excess wire makes for a noisy amp.


The stock 5F1 board has a "socket" side and a "ground" side. Controls go near the ground. There's less nioise near the ground.



Sockets obviously go on the "socket" side of the board. Rever to Rule 1, less wire is better. So... the preamp socket should go closest to the preamp parts. The 6V6 goes near its parts. And so on.



Keep the 12AX7 as far as you can from the power supply.


5Y3 goes as close as it can to the power transformer.


You'll turn your board over when you install it so your layout should be "good enough". OT is probably too close to the preamp tube but it's shielded. You might try putting it inside the chassis. You'll find there's a big empty space there when you assemble your amp. Just flip it over, put it inside. You can always change it to what you ahve if it doesn't work.

[hackworth1]

Champ 600 Ri with a 5F1 p2p? If so, is that the original OT (and PT)?

No I used different xformers. The stock 600 PT has no filament winding for Tube rectifier.

Muchxs has pointed out the importance of layout.

The stock 5F1 board has a "socket" side and a "ground" side. Controls go near the ground. There's less nioise near the ground.

Sockets obviously go on the "socket" side of the board. Rever to Rule 1, less wire is better. So... the preamp socket should go closest to the preamp parts. The 6V6 goes near its parts. And so on.

The OP has the orientation of the board flipped so that the board inputs are facing the tube sockets.

This should be corrected. Where are the inputs and volume pot to be located?

[charisjapan]

Originally Posted by hackworth1

Champ 600 Ri with a 5F1 p2p? If so, is that the original OT (and PT)?

No I used different xformers. The stock 600 PT has no filament winding for Tube rectifier.

Thanks, hackworth1. I'll start another thread about this... Sounds fun!

[johnlau]

muchxs, hackworth1 & charisjapan, thanks for your comments.

I have been working very hard in the past 3 days and got all the components assembled.

However, my amp is not working......here are the details and grateful if any one can tell me what went wrong.

1. without any tubes, turn the amp on for a few minutes, the indicator light is on and nothing strange happened, switch off the amp

2. install the 5Y3GT, turn the amp on for a few minutes, the indicator light is on and nothing strange happened, can see the 5Y3GT tube is glowing, switch off the amp

3. install the 12AX7, turn the amp on for a few minutes, the indicator light is on and nothing strange happened, can see the 12AX7 and 5Y3GT tube are glowing, switch off the amp

4. connect the amp to a 10” celestion 8 ohm speaker (G-10D-25), install the 6V6 tube, tube the amp on, indicator light is on and the tubes are glowing, but there is high frequency “vee” sound coming from the amp, not sure which part of the amp generated this “vee” sound, turn the amp off

5. here are the voltage measured at different points (with 3 tubes installed and the “vee” sound)
16uf capacitor and the chassis ground – 400V
8uf capacitor and the chassis ground – 290V
8uf capacitor and the chassis ground – 240V
25uf capacitor and the chassis ground – 15V
Pins 1 and 6 of the 12AX7 and the chassis ground – 240V
Pins 3 and 8 of the 12AX7 and the chassis ground – 1.2V
Pin 9 of the 12AX7 and the chassis ground – 4.8V AC
Pins 4/5 of the 12AX7 and the chassis ground – 4.8V AC

Dun know what went wrong, but I guess it’s something wrong with the 6V6 tube or the output transformer. Appreciate if any members can offer comments to help me to get my amp fixed. Thanks.

I attach herewith some photos of my amp for your reference.

[muchxs]

Originally Posted by johnlau

3. install the 12AX7, turn the amp on for a few minutes, the indicator light is on and nothing strange happened, can see the 12AX7 and 5Y3GT tube are glowing, switch off the amp

4. connect the amp to a 10” celestion 8 ohm speaker (G-10D-25), install the 6V6 tube, tube the amp on, indicator light is on and the tubes are glowing, but there is high frequency “vee” sound coming from the amp, not sure which part of the amp generated this “vee” sound, turn the amp off

Unsolder the output transformer primary wire that connects to Pin 8 of the 5Y3. The connection may be on the circuit board rather than the tube socket.

Unsolder the output transformer primary wire that connects to Pin 3 of the 6V6 tube. Move that to Pin 8 on the 5Y3.

Solder the wire you removed from Pin 8 / 5Y3 to Pin 3 / 6V6.

Re-test the amp.



Notes: I like to keep my filament wire flat to the chassis. Contrary to Urban Legend it's quieter. It also keeps it out of the way in a tweed amp, makes the amp a lot easier to troubleshoot and service.

Tidy up / shorten the wires where you can. Push the wires at the control panel tight to the chassis.

Volume pot should be where the power switch is. Power switch should be where the volume pot is. Better still, move the power swich to the back of the amp.

[hackworth1]

I concur with the evaluation and the recommended remedies prescribed by muchxs.

Where did you get that sharp looking chassis?

[johnlau]

muchxs, thanks for your comments, I have swapped the wire from Pin 8 / 5Y3 and Pin 3 / 6V6. The "vee" sound disappeared, I then noticed that I made a silly connection mistake at the output jack. I re-solder the wires at the output jack and the amp is on! I am really happy with my first build! Thanks again!

Regarding your comments about the position of the volume control/on-off switch. I have tried to relocate them, but I don't see big improvements. (well, I think I will keep the layout as it is)

Thanks again!!