Question about newly finished D-Lite. FIXED... or?

[Svempan]

dogears,

Thanks a lot.

I think I see your point, but I think(!) I will do more changes only after Johan has tried his amp for himself.

Personally I think the overdrive sound is rather good now, but I really want to know what Johan thinks.

What "sweet OD" is, I guess is rather personal? As you can see in the schematic I linked to, I've also used values on the two serial resistors in the OD section to get what is described as "Removes low midrange mud" and "Adds upper midrange clarity" in the ODS-101-NON-HRM schematic. Maybe those descriptions also could be described as LESS sweet OD... maybe...

But as I said, I think I see your point. For my personal taste I wouldn't be too surprised if I would like it to be at least about 230-240V on the plates of V1, and about 200-210V on the plates of V2... As you probably know, that's possible to do. I have had good experiences from other amps to have separate B+ supplies to the preamp stages (for example like in Fender Bassman 6G6, or Matchless C30 or Spitfire).

Of course I may be wrong but I also think that your suggestion to use a string of 22K/2.2K is more suitable if the B+1 would have been about 450-460V which I would have preferred, but that’s not the case with this power transformer (it is 410-420V depending on the wall voltage)

For this amp I have also been influenced by the voltages shown on the schematic for the “1997 Humble Overdraft Specimen” on Schematic Heaven.

Yes, I will let you know what happens... (Maybe I can't resist trying voltages as per your suggestions today... )

[Svempan]

Of course I couldn’t resist trying lower plate voltages on V2 as per dogears’ suggestions... ... Yes, I know I said I should send it to Johan as it was, but if it could be better before I did that, I wanted to do it...

First I like to make clear, and repeat, that the ugly distortion that this thread is about occurred in the first gain stage, before the Volume control. Therefore it could be heard even at very low volume settings. With the Master Volume full up, the distortion was there at any settings of the Volume control (up until the rest of the amp started to distort when it was more difficult to hear among the other distortions). The distortion wasn’t pleasant sounding. Normster’s description “almost sounds like a bad speaker” is rather good.

Second: I also would like to clarify that the B+ voltage from the power transformer in this amp is rather low, as I see it. It’s about 420V instead of like 450-460V that I personally think would be more suitable in this kind of amp. I guess this D-Lite kit from Brown Note mainly is made for 6V6s as output tubes, and therefore the transformer is like this. It also wouldn’t surprise me that much if the power transformer really is a substitute for a Fender Vibrolux Reverb transformer (which would be “big” for a 6V6 amp), but I may be wrong...

Third: I’m a little confused about hardly sticking to certain values of the resistors in the voltage dropping string, and that the voltages themselves then are subordinated the resistor values. Isn’t it the respective B+ voltages themselves that are more important? Comments?

Fourth: Even if this type of amp is an overdrive amp, I personally think (thought) that it also should have a good clean sound. Comments? What do you others think? Or is the clean sound a compromise for getting an as good overdrive sound as possible?

Any way. I thought that dogears’ statement that lower plate voltages on V2 would give a sweeter overdrive sound, was right (lower than 230V that it was, that is). The voltage dropping string I had after the choke replacement resistor was; 1k-10k-10k. I liked the voltage to the phase inverter so I didn’t want to change the 1k resistor. I then tried 1k-22k-1k and 1k-22k-2.2k. The overdrive sound with those dropping strings maybe can be said to be sweeter sounding and I liked it, but the clean sound was worse than before .

After the 1k resistor (B+3, that feeds the phase inverter) I then made separate voltage feed to V2 and V1 instead. V1 and V2 now have their own, separate dropping resistor and filter capacitor.

The plate voltages on V2 now are 208V and 210V. To V1 they are 224V and 233V.

Now the overdrive sound got better and the clean sound got much better. The clean sound got, what I would call, clearer than before and as that sound feeds the overdrive section in OD mode, the overdrive sound also got a little more clarity. Therefore I changed back the series resistor between V2a and V2b to 100k. I had changed it to 150k to “add upper midrange clarity”.

The ugly, almost-sounds-like-a-bad-speaker-distortion in the first gain stage is now gone, even when playing with the neck pickup on my Gibson SG .

Now I like both the clean and the overdrive sound . Maybe I should have an amp like this myself...

Comments are very welcome!

[dogears]

Good job! Glad I could help.

I have been endlessly soldering and experimenting for years now and there are several things that are pretty certain. One is plate voltages and OD tone.

Fwiw, I don't know who suggested the 150K in that schematic. If anything, the higher impedence reduces clarity and lowers the knee frequency making things darker and bassier. I use 100K....

[dogears]

Oh... Try lowering the choke replacement to 300ohm, 330ohm, or 390ohm. Whatever you have on hand. Maybe try a 1K across your 500ohm. I bet you like it more!

[Structo]

Sorry for being a dumb ass but which 150K is this resistor?
Are we talking about the plate resistors or grid resistors?
And on which side? V2a or V2b?

I'd like to clean up/ make it tighter, the lower end on my D44 a little.


Thanks

[dogears]

The series attenuator between stages. The one that feeds the coax that goes to the OD level pot. Normally a 100K. The other one is the 150K or 180K that feeds the OD ratio pot.

Sorry for being a dumb ass but which 150K is this resistor?
Are we talking about the plate resistors or grid resistors?
And on which side? V2a or V2b?
Thanks

[Svempan]

Oh... Try lowering the choke replacement to 300ohm, 330ohm, or 390ohm. Whatever you have on hand. Maybe try a 1K across your 500ohm. I bet you like it more!

You bet! I have already tried that and personally I like it better with 330 ohm .

But, I like to have it as it is untill Johan himself has tried his amp. Maybe he likes the little more compression and the little less clear sound (or could it be said as being a softer sound) that it gives.

[Svempan]

...I have been endlessly soldering and experimenting for years now and there are several things that are pretty certain. One is plate voltages and OD tone...

In the amps you've done that. What main B+ voltage has the power transformers in them given under load in the amp?

Please answer! I'm really interested in your answer on that question.

Also: What main B+ voltage do you think is the best for an ODS style amp? I mean when it's in the finished amp, under load, running at idle.

[Svempan]

Sorry for being a dumb ass but which 150K is this resistor?
Are we talking about the plate resistors or grid resistors?
And on which side? V2a or V2b?

I'd like to clean up/ make it tighter, the lower end on my D44 a little.

Look at this schematic: http://ampgarage.com/forum/download/file.php?id=1178 taken from the tread on the Dumble files here "Final ODS-101 schematic" http://ampgarage.com/forum/viewtopic.php?t=1902
There was a previous revision of this where there was a note by the 100k series resistor between V2a and V2b that said that a 150k instead "Adds uper midrange clarity".

Also look at the 220k series resistor before V2a in the schematic. There's a note that says that 150k-200k "Removes low midrange mud". I have used 180k in Johans D-Lite and think it does that: Removes low midrange mud. Maybe you (we) should try both 150k and 180k as dogears says.

[dogears]

This one was my suggestion.

Also look at the 220k series resistor before V2a in the schematic. There's a note that says that 150k-200k "Removes low midrange mud". I have used 180k in Johans D-Lite and think it does that: Removes low midrange mud.

[Svempan]

This one was my suggestion.

Yes, I'm also mostly a big believer in low serial resistances. That's the main reason I posted the suggestions for a, what I think is good mod for Fender AB763 reverb channels to have only 180k instead of 3.3M as serial resistance. I did that this summer but it wasn't as good received as I had espected .

Many thanks for your comments about the D-Lite in this thread. I really appreciate that !

It would, by the way, be very interesting to get your answer on my question above about the main B+ voltage in the ODS style amps you've been working on for years.

[heisthl]

The plate voltages on V2 now are 208V and 210V. To V1 they are 224V and 233V.

When I've had V1 voltages that high I always thought the clean sound became too sterile and lost the harmonic overtones. My test has been to play Cowboy G (first position G chord) and let it ring, You should hear some harmonics dancing around behind the fundamentals. Fo me this only occurs with both sides of V1 at less than 200 volts and usually closer to 190 volts. It might be a good experiment to cliplead in an additional dropping resistor and A/B for harmonic content. There are at least 2 flavors of clean and the sterile flavor is not as musical. JMHO

[greiswig]

Deleted to avoid overlap of topics...

[johan]

I met "Svempan" this weekend with some other friend. I've played the amp all week and let the other play and just listened.
Most of them are into BF Fenders (and maybe a Plexi Marshall after dark ).
The DLite sounds, both clean and distorted, more modern vs a Fender but they all liked what they heard.
I've used it alot and like what I hear more and more. We're down to the tweaking now...

As stated before Svempan use fat strings (013) and plays a lot harder than me. Although I use both TL, ST and HB my right hand and strings (010) are lighter.

This thread started with a discussion to make the clean channel cleaner.
This can make the tone more sterile and stiffer. I want the clean tone to be warmer and sweeter.

With this background I have a question on Robben Fords Dumble amp (90's BL)-

How much time does Robben spend on the clean channel or clean channel+PAB vs. in "Overdrive mode"?

Now my clean channel is clean even with fat strings and a pretty heavy right hand.
From what I've heard Robben usually stay in clean channel and maybe some PAB for solos. Is the clean channel that dirty or does it stay CLEAN?
Maybe Robben just controls it with his attack and volume pedal.
Or does he use lead channel for his dirty tones? Haven't thought about it so I have to ask. Maybe this gives us some idea of how to dial it in.

It's a SWEET amp! Thanks Moss!

[dogears]

Hi Johan,

Try replacing the 5751 in V1 with a nice 12AX7. I have never seen an ODS with 5751. For me, they just are too lifeless and dull the OD.