Has anyone done a Speed ball upgrade to the Dark Voice tube amp?

I wanted to know if anyone had added the bottle head crack speed ball upgrade to the dark voice tube amp. I’ve been looking up mods to do to mine and a few LED mods have looked promising

Yes, I have, it requires a bit of modification however for it to work well, the Darkvoice has a lower voltage at 135VAC instead of 150VAC, but the resistors in the Power supply are 200Ohm each in the DV, instead of 270Ohm each so the DV may be running similarly to the Crack. I would say that, but the capacitors leading to the Driver tube (The two per side) have 200Ohm resistors.

Now from experience, The amp will turn on and the boards will “work”, but idk if it’s the 200Ohm resistors or the Capacitance (I’m thinking the resistors since the Crack uses 220uf Caps, albeit not in this configuration), but the amp will distort like crazy, and it may be due to the resistors there on the capacitors, also Speedball won’t fit in the DV normally (Although the C4S board will, but has that 200Ohm issue).

Honestly for Speedball to work, maybe take out those Capacitors and the 200Ohm resistors, cut the Speedball Board in Half while maintaining the necessary contacts (The C4S board though will fit fine without modifying the layout) and remove the Cathode Resistors of the Power tube and try to lay the Speedball Boards on the sides for them to fit.

Idk, the amp sounds fine without Speedball, maybe if you want you can add a C4S board to the Driver tube since that board fits perfectly inside the DV chasis, but again, you may have to either remove those side capacitors OR reduce the resistance on R1 and R2 a bit (Increasing Watt rating as necessary) until it starts to sound good (Just make sure the lower resistance resistors can handle the Heat/Power).

There are also posts on the Bottlehead Forum so you can also Deduce some stuff from there on how the C4S board works (https://forum.bottlehead.com/index.php?topic=5470.0) & (https://forum.bottlehead.com/index.php?topic=1126.0) for starters. I’ll edit this post in case I think of something though, I’m still a bit sleepy from waking up.

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Wow thank you for such an in-depth break down, I’ve been looking at mods for the DV and it looks very promising, im no stranger to soldering and putting in the time for a mod that seems very worth while. Seems that the DV when modded seems to be a tube king until about the $800 range

Oh yeah, the amp is amazing when fully modded (Just replacing the parts with better quality parts). My DV has had everything removed and modded, even the transformer, US versions of the DV have the Primary at 110, so I got an identical transformer but with a 120 Primary to actually work with US voltages as intended.

The only thing not upgraded was the Rectifier, it was replaced, but not actually “upgraded”, If you see Crack Mods, the Diodes are replaced with Cree Diodes, which are much better, and it is totally doable with the DV if you use a separate board (They have them for sale), solder the diodes to that boards, and run some wires from the PCB in the DV where the original Diode was to the Board with Crees. Voila, upgrade.

Sadly a High Inductance choke can’t be fit into the DV, due to size constraints but isn’t necessary, although it does make the background more “black”. Well you can always put the choke on the outside and make sure the terminals are well covered in electrically isolating material and that could work. Buy two and you can make the amp look more even if you do put them on the outside.

The Speedball Kit Can fit but again, requires quite a bit of modification for the board to fit, the C4S board fits perfectly and functions, but needs tweaking in order to get the best out of it and not have it distort like crazy, again I think adjusting the resistances is where it’s at, so maybe buy some cheap resistors for the board for the R1s and R2s to experiment, and once you find the right sound buy better resistors later, also obviously don’t drop resistances like crazy, small increments with appropriate wattage. Also using CCS are kinda an “Eye of the Beholder” scenario, where it can either make the amp sound better, or maybe not to your liking. Some of the more higher end amps use Plate Chokes or Resistors to do the job so stuff like Speedball + C4S won’t be an objective improvement (measurement wise maybe, but you may not like the sound later).

I mean look at the Eddie Current Studio, considered one of the great amps by many, and the tubes aren’t using CCS or Transistorized sinks.

Well there are two boards there with the Capacitors and I have no idea if those ARE CCS, and also there are two diode rectifiers, well they look like rectifiers, that I also have no idea what they do from the angle of this pic, maybe it’s a rectifier for the Heaters of the 2A3 tubes, which would explain the boards, but which would be kinda weird since the Studio has a Separate Power Supply so again, it’s weird if the heaters weren’t rectified from there but idk, I only have 1 pic of the internals, also from what I can tell, the things labeled tribute are the OT so the other Transformers in there are possibly IT (input transformers) so that the RCAs can also work balanced. Idk kinda went on a tangent, but hell it’d be cool to build a Studio if I could get a bit of more data on it, just resistances since I could probably calculate the Transformer necessary and replicate the power supply with some reverse engineering (Voltages may be off by a bit but nothing noticeable with some more data on the internals).

Speedball is great but depends on the sound you want the amp to have, but still great though when applied to the Crack, then again the Driver tube is a 12AU7 (+ Equivalents) so idk how the 6SN7 would sound, although the 6SN7 can be used with a Crack with adapters, but idk, different tubes, different tunes.

Also you wouldn’t download a movie, so don’t download spicy nudes of the Studio to bootleg a Studio at home. (This pic is pretty public though so if you’re clever enough you can probably do it, didn’t hear that from me though).


Dude this is amazing so indepth, that is true I wouldn’t mind what ive heard described with what the speedball does to the crack and probably does some good stuff for the DV. After all I use my DV for fun listening/general enjoyment so anything that adds to that is what im going for.

You’re right about the different tube for different tunes. I love the pre-amp 6SN7 tube so many possibilities. I’m definitely going to modify my DV for general improvements without going crazy.

What I mean by that is modify it with price to performance in mind seeing as its quite the king in that department. So it seems speedball and a few other mods to have that black background I’ll be doing and posting along the journey. I’ll be looking at all the notes you’ve put here and refer to them this has been the most helpful description looking at DV mods I’ll see what seems to be worth while and make a guide. Ultimate DV mod [Within reason]

If you’re going for blacker backgrounds, my first recommendation is a Transformer Swap, if you live in the US, the Primary is 110 on the Transformer, while the US voltages are 120, so swapping the transformer for one with a 120 Primary will make the Darkvoice much more quiet. You can also add resistors to the heaters to drop the voltage down but getting a higher quality transformer with the correct values may be more of a benefit all around. I have a post somewhere about new transformer values for a better performing DV all around. It’ll fix the heater issue as well as increase how much the heaters can handle if you tube swap to higher heater current tubes (Such as a CV181 tube).

I recommend getting the transformer ordered from the original manufacturer here:

They have an online chat service and tends to be quick enough on the shipping and manufacturing (~10 days). True this is the more extreme option but it’s probably going to be the most effective method. Other than that you can do the previously mentioned Cathode Bypass cap trick (Hum-Fitz Mod) to reduce noise overall, albeit you get a bit of gain due to this and the capacitor quality is rather important here, maybe go with an ELNA capacitor.

Also forgot to give you the Transformer Specs just in case:
120 VA (Just a hair over the originals Maximum Rating for a bit less heat when using heavier consumption tubes)
Primary 120V
Secondary 135V - 0.7 Amp
Secondary 6.3V - 3.6 Amp (This way you can also use 0.9-1.0 Amp Preamp tubes safely, ergo why the VA was increased a touch)).

If you live anywhere else, try to see what the primary voltage is of your transformer by removing the glue on the box surrounding the Transformer and see if it matches what’s being outputted from your wall outlet. Any difference at or above 10V is bad for the tubes and amp, heater wise (The Plates don’t really care too much about this though). This is also one of the main factors of noise in tube-rolling with this amp, and is also a reason why the Hum-Fitz Mod tends to be done to the amp. If your DV transformer primary matches your Outlet Voltage, then ignore the transformer swap.

Another mod that will generally make the background more black, is replacing the last resistor of the Power Supply to an equivalent DC resistance inductor (Or similar, I think anything +/- 30 ohms will still work). Just in case if you want to keep the 400 ohms in the Power supply, if the inductor is lets say 250 Ohms, you can buy a 15W 150 Ohm Resistor, that way the resistance is still the same, I like to overkill so if you really want to make sure heat isn’t an issue, maybe get a 20W Resistor instead for the hell of it.

Changing the Rectifier Diodes (Cree or Hexfred) will also make the amp more quiet and a bit more smooth too, and in my experience, adds a tiny bit more bass and a tiny bit more treble, depending on the diode (Albeit barely noticeable unless a direct comparison is made, and on VERY particular tracks).

Finally, you can always add the C4S + Speedball mod, which will not only make it more black, but also add a bit more speed to the amp. Generally Speedball is considered a sonic improvement to it’s respective amp (The Crack), but there are some who prefer the sound of the original. IMO, do the Transformer Swap, add the Inductor/Choke, and Play around with the Diodes (As well as other mods such as changing the Output Caps and changing components to better quality ones), before doing Speedball, since it may be possible you don’t like what Speedball will do to your amp.

Also if you do add Speedball, you may need to modify quite a bit of the amp for it to even fit, let alone function adequately. It’d almost be like making a Crack in a Darkvoice chassis essentially, depending on how you integrate the Speedball mod.

Most important of all is to be careful while modding your amp. Even simple mods like the diode swap or Output capacitor mods can be dangerous if certain precautions are not taken. Also, ALWAYS double check the amp, even if the mod has nothing to do with a certain part of the amp, make sure the amp is still grounded and the Power Supply is still soldered correctly (take pictures of the amp before and after so you can see if something is missing).

Other than that, have fun modding, it’ll really bring out the best in the Darkvoice.

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Thank you so much this has been huge for me understanding where to go with the mods next, im in Australia so ill have to look up the values for power from the wall in my region.

incredible how far I can take this and im excited to see which ones will make the most impact.

By making the DV have a more black effect do you feel that this makes the tubes you put in stand out more instead of dealing with all the other sound coming from the circuit?

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Ok, so the Euro type amps have a 220-240V discrepancy, I’d imagine since 10V up or down the scale wouldn’t really mess with anything.

Australia is 230V at 50Hz. Incredibly, due to the 220-240V discrepancy (based on Drop’s buy description), it may be possible the Darkvoice transformer may be designed with a 230V primary to take this into account, meaning it may be possible your Darkvoice won’t have hum issues. This means a transformer swap won’t be necessary, and this tends to be one of the messier mods due to having to remove the adhesive on the transformer and the casing.

Either way if you want you can crack the DV open for fun and check the transformer, but I see it as unnecessary if the numbers are right.

Check your outlets though, may be possible that your outlet has a lower/higher voltage. Google says Australian outlets are 230V, and due to the drop data, it may be a 230V primary.

I mean, more important to noise than a choke was the Transformer, as well as for the longevity of the tubes’s heaters. Essentially if I’m right, essentially your Darkvoice will be quiet from stock and have very few issues with tube rolling.

Just to explain my logic a bit, they made the US transformers 110, meaning 120 or 100 would work fine with it for other countries such as Taiwan (110) and Japan (100), with Taiwan having 110V and theoretically having the best performance stock. So by that logic, if the Euro ones can work between 220 and 240, and they wouldn’t make custom transformers for each voltage, then it should be 230, so UK and Europe wouldn’t have issues, with whatever county having 240 getting the short end of the stick. Australia, gets the benefit of being right in between, and therefore gets the best performance stock. True there is a possibility that due to the higher voltages the discrepancy may have to be less, but then again idk of Drop lets you choose 220V or 240V Darlvoices, and have to assume that it’s a similar case as to the U.S. having 110 since it falls between 120 and 100.

Oh for the new specs I guess it’d be the same but with 230V as the primary, incase you do the transformer swap, you can still use the calculations from the other post, but with 230 as the primary.

120 VA (Just a hair over the originals Maximum Rating for a bit less heat when using heavier consumption tubes)
Primary 230V
Secondary 135V - 0.7 Amp
Secondary 6.3V - 3.6 Amp (This way you can also use 0.9-1.0 Amp Preamp tubes safely, ergo why the VA was increased a touch).

Also the 135V at .7 amps may be a bit excessive, so maybe that can be dropped to .6 or .5 amps, I’ll get a more precise number since the transformer specs can be optimized to use even HIGHER current tubes, like the 6528 in conjunction with the CV181. That or increase transformer VA, as long as it still fits in the Transformer casing (200VA from that company will fit perfectly from experience, maybe a bit tight but nothing worrying).

Oh also, just learned something new, but apparently the newer CV181-Z (Shuguang Treasure Tube) is apparently compatible with standard 6SN7s, so they’re made for .6 Amps of Heating, the CV181 I’m referring to is NOS, which has a higher .9-1 Amp heater, just in case you were wondering as to WHY I kept mentioning the CV181.

Also I’m a lazy boi, so for the uber beef transformer, I’ll just do a 150VA Transformer, with some added benefits.

Primary 230V (Interchangeable with 120V or any other Primary Voltage)
Secondary 3.15V+3.15V (Center Tap To Ground For Lower Heater Hum, adds to 6.3V if done this way) (Total Current: 8 Amps AKA BEEFY) (Total VA: 50.4)
Secondary 135V (No Center Tap Necessary since this will be rectified) (Total Current: ~.737 Amps, more than enough, you could probably go to .6, but there is LITERALLY nothing Heater wise that would consume more than 8 Amps, I really can’t think of a legitimate combination that would consume nearly 8 Amps of Heater, My Super Amp has the Heaters at 7 Amps PER TRANSFORMER, and even then It’s using 3 tubes per transformer, which AT MAX can consume 7 Amps (2 x CV181 + 1 x 6528), but that is an improbable scenario since one of the tubes per side is a Shunt Regulator, so no point in using CV181 for that, also my amp is working with 150V and a 1 Amp Secondary as well, and even then that’s excessive Current wise, I just don’t want my amp to stress too much, probably will run it with 2 6SN7 and a 6080/6AS7 for now,maybe get a pair of 6528 later on, and even then, it’ll be running at 6.2A, or .6A+.6A+5A per side) (Total VA ~99.5)

Total VA: ~149.9

P: 230V
S1: 3.15V+3.15V,CT, 8A, VA 50.4
S2:135V, 0.737A, VA 99.5
VA Total: 149.9

Essentially, you can mess around with the Darkvoice however you want, and it would NEVER even get close to max operating levels on the transformer. You’d have to do something extreme like dual 6528s or Quad CV181, Which would break the amp for other reasons BESIDES the Heaters, I mean the Heater winding would still die, but other stuff might break it first.

Oh Also if you don’t want a heater center tap (Reduces Heater Hum), you can always do a virtual center tap with some resistors to ground at the ends of the heater wiring, essentially it has the same effect, so idk, you have options, that’s how I’m doing mine, so you know, you can choose.

So yes, you can put an OP transformer in the DV, and the size will work (almost 99% sure since a 200VA transformer can fit in the shell too). 8 Amps tho, is monstrous, especially for just 2 tubes, but oh boy can those tubes be literally anything you want, within reason ofc.

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I dont approve of giving my amps drugs sir


Performance enhancement substances

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Oh also, besides all of what I wrote in the last post, I really wish I had thought of these things beforehand when buying my custom amp’s transformers, I mean 7 Amp heaters are more than enough, since they can handle 2 x CV181s AND 1 x 6528, but I mean, optimization and stuff, well thank god my amp is modular, I’ll just buy 3 new transformers with the stuff that I wrote when I feel like I need it (Which I really won’t, since either way 7 Amps is alot).

Oh also this amp is it’s own thing, but I kinda found out I can independently use what is essentially a Legacy version of the Darkvoice independently, essentially giving you both a Super Amp with enough power to power almost anything OTL style when using 6528 tubes (Save for a HE-6), and a Super Dope Dark Voice (Still the Classic High Impedance Amp We All Fell In Love With, Now with German/U.S Tech!) with the corrected transformer, but sadly not the BEEF transformer I posted, but that can be swapped in about 5 minutes with the level of modularity planned for my amp, still quiet af tho, but it DOES have a 15 Henry Inductor and Mundorf Caps and Vishay resistors for literally everything. Essentially inside the amp is another amp. An AmpAmp.

Oh also this amp has three independent Power Supplies, one for the Low Power Stage, and one for each of the Dual Mono High Power Stages, the High Power stage having even beefier stuff like Mundorf 200uF TubeCaps and CCS, which will be upgraded shortly to include an extra pair of 100uF Film Caps to add to the 200uF.

Just writting this here so I don’t forget the listing for the upgrades once my amp is done:
2 x 100uF Mundorf TubeCap
2x 100uF EVO Aluminum Oil Caps
2 x 6528A Tubes (Or 5998 if Former is not Available)
2 x Custom 600/8 Ohm OT + Extra Selector Switch Circuit (In Case the Initial 6528 Tube OTL system Fails to Produce Enough GOOD Power into AEON Flows, Implementation Will be Similar As The Tuba Using 119DA Equivalents, but Enhanced to be 20Hz-20kHz)
3 x BEEF 8 Amp Heater Transformers (Optimization IF Necessary, For a Much Later Date)
1 x Astolfo Plushie (It’s To Improve Performance I Swear)


Hmm thats weird my Astflo plushie seems to be cursed… just keeps telling my I’m gay… but hey it was only $50


Hmm weird, well you can always ask it to . . .


Lord have mercy upon my soul

Funny this weird salesman sold me mine

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hey @Schizoid I read through a ton of your DV posts on here and other forums. I’m in the US and have an interest in trying to do the transformer replacement like you had done. I reached out to the company that did yours several times and was unable to make progress with them. Any recommendations?

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