found a chassis in my storage place :D

[erwin_ve]

The 2 nd gen hybrid layout have a few mistakes:
The 10k from basspot to ground is missing.
The rock-jazz switch centre position lugs have reversed wiring.

Sorry I thought I mentioned them to you.

Erwin

[norburybrook]

The 2 nd gen hybrid layout have a few mistakes:
The 10k from basspot to ground is missing.
The rock-jazz switch centre position lugs have reversed wiring.

Sorry I thought I mentioned them to you.

Erwin

Erwin,

I 'm making this without jazz/Rock so I've negotiated that one I think I've done the wiring for that on the mid boost relay and corresponding wiring to the tone pots.

As I say it's the whole added loop/OD/Clean /relay wiring I'm unsure of.


M

[martin manning]

It would go like this, I believe.
Edit: The basic idea is the same, but I see the HRM w/ on-board loop layout has some non-standard values in the loop, and it's missing a couple of grounds.

[talbany]

For serial-parallel Claus (Bluesfendermanblues) found this configuration to be superior: https://ampgarage.com/forum/viewtopic.p ... highlight=

I disagree. I actually tried this method first on my 2nd generation amp and had to remove it due to it created a small range point in the pot which made it difficult to find the sweet spot between clean/wet. Other words too touchy. This was a problem when trying to adjust on the fly in the middle of a song
As far as the bright switches go since your not having to deal with any long cables IMO a bright switch is not as critical. I don't have one on mine and don't really feel the need since the bright on the amp is usually plenty.
Others might have a different experience but this is what I found.

Tony
Here is the one I used.

Serparallel.jpg

Loop Mix control.jpg

2nd generation.jpg

[norburybrook]

oooh...my brain hurts.....these amps are complex.

wired the relays and switches.

I've added an extra 9v regulator as I'm going to try sending 9v to the footswitch so I can have a power socket for a new pedal I bought that's a combined reverb and delay. so it will just plug into a socket on the side of the footswitch for power , and I'm make a single cable with star quad that has a send and return to the amp into the pedal.

so hopefully with the FET (clean) boost, PAB boost and OD combined with reverb and delay I'll have everything I need with just one pedal, powered from the footswitch case and one multicore cable to and from the amp.

IMG_20191102_180218.jpg

IMG_20191102_180308.jpg

I 've just realised I'm short of a 33k resistor for the OD. so it's a 220k into a 33k with a 1.2m across the pair. I have the 1.2 M what can I use to get me the same function? I presume it's a voltage divider of some kind. Or I might just order a 33k resistor at great expense! My transformers are still being made so no hurry.

edit: just found some Morganite NOS 33k's I've ordered.


M

[norburybrook]

wired the main board today. It's very cramped in places and there's sometimes 6 wires trying to go into an eyelet so made for some difficult/ugly soldering ( I soldered everything underneath the board as well to make sure ). Also I noticed that these eyelets don't seem to to flow the solder well at all. After a few I scrubbed the board with a nylon dish sponge and that helped a bit, you can see it's taken the shine off the board in places.

I've got a whole selection of NOS bit's and pieces going on , some NOS Beyschlag resistors, Holco's , various ones I've collected over time and some NOS vintage caps too, not pretty but hopefully sonically good

I've grounded the loop resitor voltage divider network with all the other grounds on the board (cathodes) I presume that's OK. Also the NFB , due to the huge resistor and the layout I made I@m going to go in form the presence pot to the node the the south side of the resistor then out the north side into the 4 ohm tap, again I think that's OK.

IMG_20191103_184246-01.jpeg

M

[martin manning]

Hmm. I'd feel better if the D'lator grounds were all back at the loop jacks, but it may work out. Where are the caps for the loop grounded? I'd take those back there too. Did you see the component values I wrote in above? Lot of work there Marcus!

[norburybrook]

Hmm. I'd feel better if the D'lator grounds were all back at the loop jacks, but it may work out. Where are the caps for the loop grounded? I'd take those back there too. Did you see the component values I wrote in above? Lot of work there Marcus!

I think I've grounded everything together on the back of the board so they'll all ground at the input jack.

Edit: I only need to swap the ground jumper from the loop voltage divider to the loop cathode ground and they'll all ground at the loop.

I can split things if it would be better. The normster layout doesn't give any grounding references and I've no schematic so playing this by ear at the moment.


I didn't see the component values no, where?

edit: just seen them, are they a recent addition? I'll change them tomorrow. I don't think I've a 1.3k, can a 1.5k stay?



M

[martin manning]

Yes I edited that after a bit more study. 1k5 is fine, I think. I don’t know why the cf stage components have those values. What I’ve shown there are the Dumbeleator spec. I recall there was sometimes confusion on the recover stage Ck, 4.7u vs. 47u. I think keeping all the loop grounds together is best.

[norburybrook]

Yes I edited that after a bit more study. 1k5 is fine, I think. I don’t know why the cf stage components have those values. What I’ve shown there are the Dumbeleator spec. I recall there was sometimes confusion on the recover stage Ck, 4.7u vs. 47u. I think keeping all the loop grounds together is best.

thanks MArtin

Erwin, you built this amp what values did you use?


47uF??? that's a big difference from my 4.7 uF .....what's the correct value?

M

[martin manning]

See circuit here, first post: https://ampgarage.com/forum/viewtopic.p ... 69#p140269

[norburybrook]

See circuit here, first post: https://ampgarage.com/forum/viewtopic.p ... 69#p140269

Damn!!

yes I can see that the Normster layout isn't very clear at all regarding this, or has errors.

Going to have to order a 47uF cap and some resistors of the correct value tomorrow and redo that whole recovery loop section on my board.


M

[erwin_ve]

Marcus I used 47uF on the recovery cathode.
Fwiw the Normster loop isnt wrong, there are other Dumblelators out there that use these same values(former Ford Dlator fe.) but I suggest to use a 100k on the dropping string for the cathode follower in the PS in that case.
Grounding as Martin suggest otherwise you end up with hum.

[norburybrook]

Marcus I used 47uF on the recovery cathode.
Fwiw the Normster loop isnt wrong, there are other Dumblelators out there that use these same values(former Ford Dlator fe.) but I suggest to use a 100k on the dropping string for the cathode follower in the PS in that case.
Grounding as Martin suggest otherwise you end up with hum.

thanks Erwin, I have a 100k in there and as it's a PCB it's harder to remove than an eyelet so I'll leave it in place and use the Normster values with the 47uF and swap one of my grounds so they both go the loop jacks.


M

[martin manning]

4u7 in the recovery stage cathode would roll off some low frequency. Power supply should be like this. 3W is overkill for those two resistors. They could both be as small as 1/2W.