[DeweyCH]

I’m honestly surprised you can put higher-capacitance caps in. When you designed a circuit around this upgrade what correlating changes are needed? Different resistor values throughout?

 

[L0rdGwyn]

Looking clean as usual. Haha, much cleaner than my pyramid stack of axial vishay caps. Plus you were able to have 66uf per channel whereas mine are 40uf per channel. My go to headphones are 250ohm. The vishay’s I have do sound nice but I’d be curious to hear the difference to the TDK 33uF 250V polypropylene films. You’re almost there.

Thanks! I like a clean build for me the fun of the modifications is seeing what can be done within the size constraints of the original chassis, these were the best capacitance/size ratio caps I could find, not super cheap but thankfully they sound quite good!

I think I'm going to start between you two with the 47uf Mundorfs (since I already have them). I'm pretty sure they will fit with only moderate assistance from a hammer.

@L0rdGwyn , are you planning on any bypasses for the TDK's (a pair of ~0.33 uf's or a single ~0.66 per side)? Looks like there might be room to the insides. Or would those be sonically irrelevant given the main cap sizes?

I wasn't planning to bypass them, but certainly something that could be experimented with by @Galapac , but I will leave that up to him.

 

[L0rdGwyn]

I’m honestly surprised you can put higher-capacitance caps in. When you designed a circuit around this upgrade what correlating changes are needed? Different resistor values throughout?

When you alter the output capacitance of a cathode follower OTL like this one, the high-pass filter formed by the output capacitance and the impedance of the load will determine the low frequency cutoff point. The frequency at which the response will hit -3dB can be calculated by the formula:

f-3dB = 1/(2*pi*R*C)

Where R is the impedance of the headphone in ohms, C is the output capacitance if farads. Really nothing else that needs to be done when increasing the capacitance, all other resistor changes that were made for the circuit were done to alter the bias points of the tubes. Using a regulated supply allowed me to increase the B+ by 30-40V with a drastically higher PSRR (power supply rejection ratio, i.e., how much of the power supply noise makes it to the output), while also removing power supply electrolytics from the signal path. I adjusted the bias of the 6SN7 to a more linear point aided by an active load, adjusted the bias of the 6080 to account for the new 6SN7 bias point (since they are direct-coupled) to keep the bias current similar to the original design, although the tubes could be pushed harder.

 

[SHIMACM]

Is it normal to spend $ 180 on the amplifier and $ 950 on tubes?

I wonder if I should have bought a better amplifier instead of spending so much on tubes.

 

[Paladin79]

Is it normal to spend $ 180 on the amplifier and $ 950 on tubes?

I wonder if I should have bought a better amplifier instead of spending so much on tubes.

You can use the tubes in another amp and you have not paid much for the Darkvoice. If left as it is you will appreciate other amps so much more.

Oh and tubes are a good investment, they are gaining value all the time.

 

[bcowen]

Is it normal to spend $ 180 on the amplifier and $ 950 on tubes?

I wonder if I should have bought a better amplifier instead of spending so much on tubes.

This is audio. "Normal" has no known correlation.

 

[Paladin79]

This is audio. "Normal" has no known correlation.

@bcowen have you run out of room yet in the Darkvoice case? I may have some extra tiger maple laying around and by next weekend I should have a pretty good idea how to extend the case even if you want to keep the current front panel. (I may end up scrapping mine.)

 

[bcowen]

@bcowen have you run out of room yet in the Darkvoice case? I may have some extra tiger maple laying around and by next weekend I should have a pretty good idea how to extend the case even if you want to keep the current front panel. (I may end up scrapping mine.)

Well, if I just put the two 47uf Mundorfs in there (one per channel) along with a pair of 0.47uf bypasses, I think they'll fit. What would be cooler though is to put 4 of them in there and get 94uf per channel. But certainly not enough room to do that in the existing chassis unless I ditch the bottom cover and add some stilts. IIRC, I *do* like Tiger maple. LOL!

 

[Paladin79]

Well, if I just put the two 47uf Mundorfs in there (one per channel) along with a pair of 0.47uf bypasses, I think they'll fit. What would be cooler though is to put 4 of them in there and get 94uf per channel. But certainly not enough room to do that in the existing chassis unless I ditch the bottom cover and add some stilts. IIRC, I *do* like Tiger maple. LOL!

Lol sure what ever you want to do in yours, 30 ufd, 94ufd practically the same thing. I just ask that you turn the Incubus to the wall so it won’t be traumatized by the stilts.

Oh and I have a few hundred MKP capacitors in case you want to solder and handful of them in your amp too Bill.

 

[Ripper2860]

Wait! His Incubus has eyes!?

 

[Paladin79]

Wait! His Incubus has eyes!?

Eyes and a soul. I had to put something extra in there since he only got a double wall cardboard cabinet.

 

[Ripper2860]

Bless its soul. I don't even want to know what that poor amp has seen Bill do with tubes.


Hey. WTH am I doing here? I don't even own a DV amp.

 

[Paladin79]

Bless its soul. I don't even want to know what that poor amp has seen Bill do with tubes.


Hey. WTH am I doing here? I don't even own a DV amp.

Me either lol, but I have one arriving soon. I repaired one once but I did not spend much time with it. I am going to mod one and see how close I can get the sound to an Incubus then probably give it away, I am running out of room. I have a couple other Chinese amps I may include lol, a package deal.

 

[L0rdGwyn]

I was about to order some parts from Mouser for various projects, including a trimmer to make a humdinger for the DarkVoice heater supply, then thought I should clip in some parts and elevate the heaters before I even bother.

So I did that, elevated the heaters ~55VDC above ground by connecting the virtual center tap to a 220K+100K voltage divider from the B+ supply. The smoothing cap isn't necessary with the regulated supply but I threw it on there for good measure on the first go-around.



Hum is now completely gone, goodbye! Tested on various tubes that were previously noisy. So this is the way, virtual center tap + elevated supply, no point in bothering with the humdinger, DarkVoice is now humphrey.

 

[therremans]

Sylvania 7A4, smooth gray plates. Found some vintage adapters that allow me to use my 6J5 > 6SN7 adapter with the 7A4s.