Implementing the D'Lite Super mod kit?

[Mark]

I have been helping a guy get his D'Lite together and he would like to get the amp completed then implement the Super mod kit.

I'm wondering if I am making a whip for my own back by agreeing to adopt this approach.

I'm also wondering if some of the mods require the amp to be disassembled to allow fitment of the components and thus the build would be worst off for this process.

Then there is the question of the sonic difference the individual mods make, some mods may be very subtle and implementing them might be more about what seems favourable rather than a real difference to the tone of the amp. An example of this to me is the feedback resistor. A lot of people like the idea of using the 4.7k value as Dumble originally used, but I like the 6.2K value in the Brown Note kit. The amp sounds livelier.

Please let me know your thoughts on the matter. Thanks.

[Bob-I]

Why not ask this question on the Brownnote forum. I think you'll get better responses there.

[Structo]

A couple things I would do.
I would be sure to wire the jumper from the OD trimmer to the 220K resistor on top of the board in case you want to do the OD entrance network mod with the .05mf cap.

I would also wire it so the flying leads come out the top of the eyelets for easier modding as well.

Have you seen the Tweaked version of the layout?

It has just about every mod that has been suggested here on it.

I have all those mods except for a couple I didn't care for and I like the way my amp sounds.

[Mark]

Dear Bob

I did try to gain access to the Brown Note forum but I don't think it is simply a matter of signing up and getting a password. I could be wrong though?

Dear Structo

I have seen the tweaked layout, but to be frank, I would have to try those mods out for myself. I did try and reduced the value of the feedback resistor from the stock 6.2K to values as low as 2.7K and the amp sounded much less lively and there was no increase in performance from the presence control. I put this down to the 90 watt Celestion speaker that I was using not requiring a lot of damping due to the weight of the cone.

OD entrance network mod with the .05mf cap.

What does this mod really do?

I have been thinking of replacing the 500OHM resistor with a choke I have on hand, should be interesting.

Thanks for your replies. Much appreciated.

[brownnote]

I just PM you a sign up code Mark, we had a big surge of porn and spam sign ups so we made it a little harder to sign up, make sure you email me with your username so I can activate the account.

The mod kit has pretty much all the parts needed to do most of the mods and voicing discussed here; bluesmaster PI, skyliner tonestack, OD entrance mods, high plates, 100K plates, cathode bypass caps, master vol bright caps, treble bleed, LNFB switch mod, snubber caps, dropping string, etc.

[heisthl]

The OD entrance mod is only useful to remove some bass from the signal entering the OD. (i.e.if you want the low notes to distort less). It is especially helpful on amps where you want to up the V1b bypass cap to 10uf for a fuller clean tone. Personally I like the combination of a 10uf bypass and a .02 coupler for cleans. I generally do the entrance mod as part of the build but jumper across it so you have an easy "tweak" point.

[Mark]

The OD entrance mod

I did the calculations and I have the entrance mod reducing the value of the 0.022uF coupling cap to roughly 0.015uF. I would have thought you'd get a similar or bigger change by reducing one or both or the cathode bypass caps?

Is there a bit more to this mod that I'm missing?

[Structo]

Which .022uf cap are you talking about?
The OD entrance cap is .05uf.

[Mark]

The coupling cap on the plate of V1b is 0.022uF, when the overdrive stage is switched in the 0.05uF cap is effectively in series with this 0.022uF cap. This reduces the effective value of the coupling cap (which is now composed of two caps in series.)

This rolls off the bass response somewhat as the value of the coupling cap is now 0.15uF, but this could also be achieved by reducing the size of the cathode bypass caps.

[greiswig]

The coupling cap on the plate of V1b is 0.022uF, when the overdrive stage is switched in the 0.05uF cap is effectively in series with this 0.022uF cap. This reduces the effective value of the coupling cap (which is now composed of two caps in series.)

This rolls off the bass response somewhat as the value of the coupling cap is now 0.15uF, but this could also be achieved by reducing the size of the cathode bypass caps.

Just an FYI, see https://tubeamparchive.com/viewtopic.ph ... sc&start=0. I think my reply in that thread got lost in the fray, because nobody has commented on it and it's the last item on page 1. But...

I don't think the cathode bypass caps do exactly the same thing as the coupling caps. From what I can tell, the bypass caps are actually a shelving filter, so although the response will drop off to a point, at some non-zero point the response flattens again. The coupling caps actually continue their slope down at some rate, e.g. 6db/octave. Either one might be useful depending on what problem you're trying to solve.

Someone correct me if I'm wrong about this...

[Structo]

The coupling cap on the plate of V1b is 0.022uF, when the overdrive stage is switched in the 0.05uF cap is effectively in series with this 0.022uF cap. This reduces the effective value of the coupling cap (which is now composed of two caps in series.)

This rolls off the bass response somewhat as the value of the coupling cap is now 0.15uF, but this could also be achieved by reducing the size of the cathode bypass caps.

Thanks for that Mark.
I never really put that together, now it makes complete sense why, after I added the .05mf cap on the OD entrance why the bass went down.

[Mark]

Tom

Have you worked through the Super mod kit Brown Note offers?

I think the mods I'm most suspicious of are the power supply mods, I don't think it is simply a matter of transferring values from one amp to another.

What are your thoughts?

[Structo]

No I didn't buy the kit per say. Moss was kind enough to send some parts that I used along with others that I had on hand.

If you have seen the Tweaked layout, I have most of that implemented in my amp.
I went back to the .05uf mid cap after trying the .01uf but I left the 250K mid pot in place.
The 500K master pot is a typo I believe because it is a 1M.

I haven't adjusted the voltages much other than with the 330R choke resistor that I installed.
I have 190-195v on V1, 204v on V2, 292v on V3 and 434v on the plates of the 6L6's.

I have the relays for a two button footswitch for OD and PAB.
I also have it wired on the PAB relay so the bass pot is jumpered on the right two lugs when in normal play but become disconnected when the PAB kicks in.
That works pretty well but I may experiment with a 100K pad on the wire to the relay.
Running Winged =C= 6L6's.

[Guitarman18]

Structo,

do you still have your presence wired as per the layout. ie. Is lug 1 connected directly to earth as it appears to be on the diagram or have you corrected it to original Dumble method.


Cheers, Paul.

[Structo]

I have it wired ala Dumble with the 4K7 feedback resistor.