Tube choice in the Dumbleator?

[Mark]

As the Dumbleator does tend to darken the sound of the amp somewhat.

I was thinking a "bright" sounding valve would be the ticket, perhaps something like a JJ ECC83S or a JJ ECC803S, though a Sovtek tube could be a little dark sounding (based on my experience with the 12AX7LPS.)

What have you experienced?

Thanks.

[bluesfendermanblues]

As the Dumbleator does tend to darken the sound of the amp somewhat.

I was thinking a "bright" sounding valve would be the ticket, perhaps something like a JJ ECC83S or a JJ ECC803S, though a Sovtek tube could be a little dark sounding (based on my experience with the 12AX7LPS.)

What have you experienced?

Thanks.

IMO ElectroHarmonix ecc83 is the brightest tube I know of. Second is the Sovtek 12AX7WA - but they both lack a little bit of 3D and warmth.

I perfer JJ ECC83S in both my D'lators. I don't consider this tube to be bright, but warm and mid oriented....works great in pos V1 and V2 in my Bluesmaster.

[boldaslove6789]

For a Nos ax7 in the D later I prefer amperex ecc83 long gray plates.

[CHIP]

I have a Sovtek 12ax7LPS in mine.

[Mark]

I doubt I'll be putting an NOS tube into the D.L. at the moment. Past experience with the P.I. stage would indicate the JJ ECC83S or ECC803S will be brighter sounding than the Sovtek 12AX7LPS. Mind you the LPS is gold in the P.I.

[Structo]

If you find the Dumbleator is too dark sounding (I did) you can manipulate the value of the resistor (220K) that feeds the second grid.
That high value attenuates too much high frequency IMO.
I suppose that is why the Ford amp has a 68pf bright cap on the master.
So you can either try the bright cap or a smaller grid stopper on the Dumbleator.

I can't remember but I think I went down to a 50K grid stopper before I liked how it sounded.

[Mark]

Dear Tom

That is interesting. looking at the circuit there is a 500pF cap across the 220K resistor, which you'd think would restore some of the highs, but obviously not enough.

https://tubeamparchive.com/download/file.php?id=11839

I think I'll start with the type of valves and see what sort of variation I have to play with, then move to circuit changes.

It is a timely process, but I shouldn't have any nasty surprises with different valve brands.

[dogears]

Hands down NOS here. Although I have had reasonable results with the JJ ECC83S.

I prefer the Philips factory long plates OR a nice RCA Blackplate OR Telefunken Ribbed OR Herleen delta code short greys.

All better than new production for me.

[David Root]

boldaslove6789, that is one expensive tube! I have several short plate Amperex 12AX7s but NOS long plates are like hen's teeth and $150 if you can find them, they are right up there with longplate Mullards & Telefunkens.

If you have a large stash and wouldn't miss one or two.......PM me, please!

[Structo]

Dear Tom

That is interesting. looking at the circuit there is a 500pF cap across the 220K resistor, which you'd think would restore some of the highs, but obviously not enough.

https://tubeamparchive.com/download/file.php?id=11839

I think I'll start with the type of valves and see what sort of variation I have to play with, then move to circuit changes.

It is a timely process, but I shouldn't have any nasty surprises with different valve brands.

I know, you would think the 500pf bypass would keep the treble up but that wasn't my experience.
But a few other guys mentioned that their Dumbleator was too dark as well when I posted about my problem.
I was told that was the resistor to experiment with and it was.

That is the correct schematic to build by with the 47uf bypass.

At the time of my build it also seemed the consensus of the group that tube type or brand didn't mean too much in this circuit.
Maybe that has changed but I never heard much of a difference between tubes although I think I have a LP Raytheon in there.

Make sure you have around 30v on the cathode follower cathode before you do much else.
The following is from Brandon at Bludotone

Real Dlators can have in the 255V range on the pin 1 of the cathode driver section. Around 28-31V on pin 3 if using the 27K/1.8K combo.
The recovery amp has 230-235V on pin 6.

Adjust the 27K tail to get the bias voltage right.

Not sure what you did for a power transformer but I used a Fender stand alone reverb transformer so my voltages were different and so my dropping resistors were different as well.
I also included a choke in my build because I didn't want any hum from the loop at all.

[boldaslove6789]

boldaslove6789, that is one expensive tube! I have several short plate Amperex 12AX7s but NOS long plates are like hen's teeth and $150 if you can find them, they are right up there with longplate Mullards & Telefunkens.

If you have a large stash and wouldn't miss one or two.......PM me, please!

David,

Yes they are getting rarer but they're totally worth it. They can be had on Ebay for a decent price from a reputable seller. Plus they last 2-3 years in a D-lator. I'm on my last one right now....Sorry.

[dogears]

All three of my lators are very smooth and not dark at all. There must be something wrong if you feel it is too dark.

Cables maybe?

[Mark]

I haven't been to specific about the cables as I've always turned up the master volume on the amp so there is plenty of signal going through the cable.

I'll try that next, that said and done. I find the tone of the overdrive improves and the amp doesn't have to be turned up as loud to get good tones.

[dogears]

That may be the issue! Turning up has no efffect on the highs. Use no more than 2-3 foot low cap cable. RG400 is nice. Or even George L or similar. I bet you get your highs back!

I haven't been to specific about the cables as I've always turned up the master volume on the amp so there is plenty of signal going through the cable.

I'll try that next, that said and done. I find the tone of the overdrive improves and the amp doesn't have to be turned up as loud to get good tones.

[212Mavguy]

Am using a VOS telefunken ribbed plate ecc83/12ax7 in my C-lator. Less expensive than an Amperex long plate. I like the compression and smooth harmonics that the ribbed plate Tele brings, as well as a slightly brighter tone than the smooth plate. An excellent alternative to that Amperex long plate is the Siemens long plate, also bright on top and very detailed harmonics but ususally going for less than the Amperex unit on the 'bay.