imperial build questions

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Bieworm
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imperial build questions

Post 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
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Re: imperial build questions

Post by crgfrench »

I believe the recto near the PTX should be fine. Looks nice!
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Re: imperial build questions

Post by Bieworm »

Thx
Ground buss ready
16024416261837129334328170184372.jpg
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Re: imperial build questions

Post by Bieworm »

Board wiring connenctions completed
16025323380838590006650295360084.jpg
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Re: imperial build questions

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20201013_214008.jpg
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Re: imperial build questions

Post by Bieworm »

16029582926657969887873748190192.jpg
16029583231823390126892130431398.jpg
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.
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Re: imperial build questions

Post 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.
16029587624172224460308912492247.jpg
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...
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Re: imperial build questions

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Re: imperial build questions

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Re: imperial build questions

Post 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?
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Re: imperial build questions

Post 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.
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Re: imperial build questions

Post 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
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Re: imperial build questions

Post 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
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Re: imperial build questions

Post 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
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Re: imperial build questions

Post 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.
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