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imperial build questions

Posted: Sat 10/10/20 10:38 am
by Bieworm
hey

On my new build I would like some advice on the chassis layout.
V1+2 = preamp CH1 and 2
Switching relays board
V3+4 = reverb
V5 = PI
V6+7 = 6V6 Power tubes
V7 = 5U4 rectifier tube
The blue cube is the relays power supply.

Laying things out pushes me to put V7 in the corner next to the PTX. Is that all right?

Are there any other anomalities you think of by seeing this layout?
The choke will be next to the PTX and the OT next to the choke ( standard DR layout )
chassis layout.jpg
chassis layout rev1.jpg
chassis layout rev1.jpg

Re: imperial build questions

Posted: Sat 10/10/20 2:29 pm
by crgfrench
I believe the recto near the PTX should be fine. Looks nice!

Re: imperial build questions

Posted: Sun 10/11/20 1:41 pm
by Bieworm
Thx
Ground buss ready
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Re: imperial build questions

Posted: Mon 10/12/20 2:53 pm
by Bieworm
Board wiring connenctions completed
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Re: imperial build questions

Posted: Wed 10/14/20 2:38 am
by Bieworm
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Re: imperial build questions

Posted: Sat 10/17/20 1:12 pm
by Bieworm
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Next is wiring the heaters. Quite a challenge in this chassis. I'm going to make them fly over the sockets and push the strain in the upper corner of the chassis.

Re: imperial build questions

Posted: Sat 10/17/20 1:21 pm
by Bieworm
After that I will wire the power supply.
Then I will solder the wires from the board to the sockets and pots. I made a separate wiring layout for that.
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Well.. I changed the position of the relays to the frontside. The footswitch will be jacked in there too. The channel switch is next to the single input. I took a generic DR frontplate. Eventually I will do a custom made for this amp...

Re: imperial build questions

Posted: Sat 10/17/20 1:32 pm
by Bieworm
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Re: imperial build questions

Posted: Sun 10/18/20 3:21 pm
by Bieworm
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Re: imperial build questions

Posted: Thu 10/22/20 4:11 pm
by Bieworm
Josh

Do you happen to have a voltage chart for 18 watts running on 6V6?
My imperial build is finished and I would like to know if the votages are in the same ballpark...

my 6V6 voltages:

pin 2: 21V
pin 3: 423V
pin 4: 342V
cathode resistor 250R

if I fill out the robrob tube bias calculator I think I have 113% which is way too high and I think I'll have to raise the cathode resistor, correct?

Re: imperial build questions

Posted: Thu 10/22/20 5:56 pm
by JMPGuitars
Bieworm wrote:
Thu 10/22/20 4:11 pm
my 6V6 voltages:

pin 2: 21V
pin 3: 423V
pin 4: 342V
cathode resistor 250R

if I fill out the robrob tube bias calculator I think I have 113% which is way too high and I think I'll have to raise the cathode resistor, correct?
I haven't built my 6v6 amp yet. It will probably be awhile before I have any reference voltages beyond the tube datasheets (which are all over the place).

Pin 2 is a heater, I assume you mean Pin 8 for cathode?

What kind of 6V6 tubes are you using? The type and brand effect your safe operating voltages.

You may want to drop your B+ and plate voltage, especially if you're sticking with 450V filter caps. Those caps should be rated higher. AC voltage x 1.41 + 10% or 20% to be safe (something like that). The first couple cap cans need to be rated higher than the max B+, and you can assume the B+ will spike a little when the amp first turns on.

Re: imperial build questions

Posted: Fri 10/23/20 4:38 am
by Bieworm
Ok I will order the 500V or more if I can find them. Only the 2 first will benefit from that I guess. The B+ ain't even high enough by a few volts, so I'll leave that alone. With 330R cathode resistor the bias is at 99%, and the amp sounds awesome!!! Listen. AND GOOD REVERB!!!

https://www.dropbox.com/s/k7pm8migiki1f ... s.m4a?dl=0

Re: imperial build questions

Posted: Fri 10/23/20 6:43 am
by JMPGuitars
Bieworm wrote:
Fri 10/23/20 4:38 am
Ok I will order the 500V or more if I can find them. Only the 2 first will benefit from that I guess. The B+ ain't even high enough by a few volts, so I'll leave that alone. With 330R cathode resistor the bias is at 99%, and the amp sounds awesome!!! Listen. AND GOOD REVERB!!!

https://www.dropbox.com/s/k7pm8migiki1f ... s.m4a?dl=0
I would drop it further, try to get closer 75% to 85%. Maybe try a 420 to 450 ohm.

Overall it sounds good, but I think the distortion needs more crunch. I like the clean tone. The light dirt is nice, it's when you get heavier that it loses definition.

Thanks,
Josh

Re: imperial build questions

Posted: Fri 10/23/20 8:11 am
by Bieworm
JMPGuitars wrote:
Fri 10/23/20 6:43 am
Bieworm wrote:
Fri 10/23/20 4:38 am
Ok I will order the 500V or more if I can find them. Only the 2 first will benefit from that I guess. The B+ ain't even high enough by a few volts, so I'll leave that alone. With 330R cathode resistor the bias is at 99%, and the amp sounds awesome!!! Listen. AND GOOD REVERB!!!

https://www.dropbox.com/s/k7pm8migiki1f ... s.m4a?dl=0
I would drop it further, try to get closer 75% to 85%. Maybe try a 420 to 450 ohm.

Overall it sounds good, but I think the distortion needs more crunch. I like the clean tone. The light dirt is nice, it's when you get heavier that it loses definition.

Thanks,
Josh
I will drop that with 180+220R in series. And see where that puts it. The crunch is plenty imho, but the recording is through 2x10 sh*tty jensens. I might start tweaking when its in its 2x12 cab. There's a g12h30 and a classic lead waiting for it. But I'm doing the combo adjustments at the moment. I had to narrow it 1".
Thanks to you I did a success job. It's quiet, well laid out and I have done a lot of preparation this time. It's a hybrid deluxe reverb/tweed deluxe preamp with a cathode bias 2x EH 6V6GT poweramp. But it gives wayyyy more useable crunch than a tweed deluxe. The topology is 18W style.
Too bad for the turrets... my supplier of good turrets changed its supplier and now there were the crap unsolderable turrets delivered. Against good practice I ended up slightly drilling the inner holes to remove the coating and soldered all components in those holes. It went very well, but I'm aware this is not to your liking.. neither mine. But I discovered this when the turretboard was finished and it's like 90 turrets in there...
But I'm pretty happy with the result.. definitly because it worked just fine on the first flip of those switches
20201023_115631.jpg

Re: imperial build questions

Posted: Fri 10/23/20 8:46 am
by JMPGuitars
Bieworm wrote:
Fri 10/23/20 8:11 am
I will drop that with 180+220R in series. And see where that puts it. The crunch is plenty imho, but the recording is through 2x10 sh*tty jensens. I might start tweaking when its in its 2x12 cab. There's a g12h30 and a classic lead waiting for it. But I'm doing the combo adjustments at the moment. I had to narrow it 1".
Thanks to you I did a success job. It's quiet, well laid out and I have done a lot of preparation this time. It's a hybrid deluxe reverb/tweed deluxe preamp with a cathode bias 2x EH 6V6GT poweramp. But it gives wayyyy more useable crunch than a tweed deluxe. The topology is 18W style.
Too bad for the turrets... my supplier of good turrets changed its supplier and now there were the crap unsolderable turrets delivered. Against good practice I ended up slightly drilling the inner holes to remove the coating and soldered all components in those holes. It went very well, but I'm aware this is not to your liking.. neither mine. But I discovered this when the turretboard was finished and it's like 90 turrets in there...
But I'm pretty happy with the result.. definitly because it worked just fine on the first flip of those switches 20201023_115631.jpg
Yeah, mediocre speakers would have that effect too. I look forward to hearing it with the right speakers/better bias.

It's all about prep work my friend. That's the key to success. You've certainly come a long way, and you're building some solid stuff now.

One trick you can also try with those turrets is to hit them with a wire brush, and then try pre-tinning them before installing anything.

Re: imperial build questions

Posted: Fri 10/23/20 8:53 am
by geoff 1965
i think that's pretty good for an initial fire up! what voltages do you have on the 6V6's?

Re: imperial build questions

Posted: Fri 10/23/20 9:01 am
by Bieworm
JMPGuitars wrote:
Fri 10/23/20 8:46 am
Bieworm wrote:
Fri 10/23/20 8:11 am
I will drop that with 180+220R in series. And see where that puts it. The crunch is plenty imho, but the recording is through 2x10 sh*tty jensens. I might start tweaking when its in its 2x12 cab. There's a g12h30 and a classic lead waiting for it. But I'm doing the combo adjustments at the moment. I had to narrow it 1".
Thanks to you I did a success job. It's quiet, well laid out and I have done a lot of preparation this time. It's a hybrid deluxe reverb/tweed deluxe preamp with a cathode bias 2x EH 6V6GT poweramp. But it gives wayyyy more useable crunch than a tweed deluxe. The topology is 18W style.
Too bad for the turrets... my supplier of good turrets changed its supplier and now there were the crap unsolderable turrets delivered. Against good practice I ended up slightly drilling the inner holes to remove the coating and soldered all components in those holes. It went very well, but I'm aware this is not to your liking.. neither mine. But I discovered this when the turretboard was finished and it's like 90 turrets in there...
But I'm pretty happy with the result.. definitly because it worked just fine on the first flip of those switches 20201023_115631.jpg
Yeah, mediocre speakers would have that effect too. I look forward to hearing it with the right speakers/better bias.

It's all about prep work my friend. That's the key to success. You've certainly come a long way, and you're building some solid stuff now.

One trick you can also try with those turrets is to hit them with a wire brush, and then try pre-tinning them before installing anything.
Yet another lesson learned with the turrets... no more assumptions. Test befor the works..the FET tremolo works great too.. no thumping at all.
Have to change the volume pot on the clean channel. Because of the relays board I had to put in a 16mm pot and all I had was this dodgy 500k log. It doesn't operate as it should.

Re: imperial build questions

Posted: Fri 10/23/20 9:25 am
by Bieworm
geoff 1965 wrote:
Fri 10/23/20 8:53 am
i think that's pretty good for an initial fire up! what voltages do you have on the 6V6's?
Think so too..

pin 8: 25V
pin 3: 429V
pin 4: 353V
cathode resistor 400R (bias 85%)
Cath bypass cap 22uf/100V (ain't that low?)

Also put in a 1/4 power switch. Nice for home playing

Re: imperial build questions

Posted: Fri 10/23/20 1:59 pm
by JMPGuitars
Bieworm wrote:
Fri 10/23/20 9:25 am
Think so too..

pin 8: 25V
pin 3: 429V
pin 4: 353V
cathode resistor 400R (bias 85%)
Cath bypass cap 22uf/100V (ain't that low?)

Also put in a 1/4 power switch. Nice for home playing
Much better dissipation! Post a new demo once you have the good speakers hooked up.

Your cathode voltage is 25V, don't you think 400% is a good enough safety margin? ;)

Re: imperial build questions

Posted: Sun 10/25/20 9:12 am
by Bieworm
99% finished.. a few hardware stuff and the reverb bag ( have to beg my wife to use her sewing machine )
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