My Khozomo board was dead within hours of receiving it. I swear it couldn't have received more than the 5 volts required to power it up. I suspect a voltage spike from the voltage reducer I bought on switch on. I'm waiting to hear if they'll send me another control board. But I'd say treat with great care if you do get one - anti static wrist bands and all of that it's way less robust than most DIY Audio sold projects.
No, I am saying that the switching is not perfect on my 47 step unit, and a stepped attenuator may induce ringing in the nutube unless steps are taken to isolate the board. I do like the feel, the level control, and the sound of the 47 step unit, but I can't say how it compares to the TKD because each are installed in different designs. The Gold Point is 100k and the TKD is 50k, so not apples to apples.
Sorry that I can't give a comparison on the sound of the two units, but the Gold Point does seem transparent.
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I've used two of them in builds for friends, and never had a problem, but the version I used had a five volt power supply board included with the main board. Did yours include the small supply board?
Have you contacted GoldPoint to see if they will provide a new one as this seems to be a defect. I have a difficult time believing that the Elma switch is properly functioning if both decks do not exactly switch.
Thank you for the response guys. I know the microphonics thing has been done to death already. The DIYAudio kit has vented top and bottom panels. I have blocked them with duct tape, and let the board sit loose on top of rubber washers.. This has helped a bit. I just got some Sorbothane in to play with. Unfortunately the washers are big 0.25"i.d. and 0.5"o.d. I have some nylon mounting hardware that might fit them.
Do you think things would overheat if I stuffed the cabinet like a speaker box?
Do you think things would overheat if I stuffed the cabinet like a speaker box?
I caution you against stuffing the cabinet with batting or other material. There will be not-insubstantial heat generated by the power supply resistors and the zener diode. I do not think stuffing the cabinet will help damping, and <may> cause a somewhat diminished lifetime for your electrolytic capacitors by reducing venting.
I think a better approach (which I will be using) is to add mass nd dampen the cabinet sides, top and bottom; use isolating standoffs to old the PCB of the bottom plate, and dampen the tube with the sorborthane as you intend.
Any chance you could provide some details and photos of the boards, if possible?
I have noticed some subtle differences. The lower pot values theoretically can have less noise. Perhaps that's why the standard value for headphone amplifiers is 10K, where low level noise is really critical.
Preamps typically use 20K, 50K or even 100K. Critical pot value really depends on your source impedance. Most solid state sources have no problem driving as low as 10K.
The pot shown on Papa's B1K-DIY schematic is 50K. I've listened to the Alps RK27 (blue velvet) in both 20K and 50K on the BK1 circuit and prefer the 20K. But it is all just preference.
Some people claim to hear the difference between the Alps and the more expensive TKD pots, or switched precision resistor ladders, such as the Gold Point. It's hard to say whether differences are due to channel tracking, conductor materials, construction or load on the source and/or input circuit. Or a combination of all of the above. On headphones, I can hear the difference between an inexpensive precision stepped DACT control and the RK27. Although I prefer the DACT, I can't abide the lack of fine level control (steps are too large) and can't see spending $250 on a 47 step Gold Point. So I, like others, find the RK27 a good compromise in value vs performance.
My B1 Korg has now been passed onto the individual who has kindly offered to Assemble it.
It will have a DACT 50K as a Volume Control.
It also needs a Power Supply to be purchased, to date I have three recommendations.
I like the idea offered that the design does not lend itself to boutique Hi End Power, but excels with lesser quality supplies, any further suggestions for a power supply will be appreciated.
I have Highly Compressed Permali Wood and Black Delrin Sheet, the Delrin can be used as a Rear Panel and Fascia Plate, with Permali as the Sides, Top and Base, it can be a unvented sealed case, as a R&D into controlling the Micophonics being recently discussed, any thoughts on this idea will be appreciated.
It will have a DACT 50K as a Volume Control.
It also needs a Power Supply to be purchased, to date I have three recommendations.
I like the idea offered that the design does not lend itself to boutique Hi End Power, but excels with lesser quality supplies, any further suggestions for a power supply will be appreciated.
I have Highly Compressed Permali Wood and Black Delrin Sheet, the Delrin can be used as a Rear Panel and Fascia Plate, with Permali as the Sides, Top and Base, it can be a unvented sealed case, as a R&D into controlling the Micophonics being recently discussed, any thoughts on this idea will be appreciated.
Why use DACT stepped series attenuator when you can use relay volume control?
DACT (series) stepped attenuators will emphasise the character of SMD resistors used, which, being SMD - is not going to be pleasant, especially at lower volume settings where there are 20-or-so resistors connected in series in a signal chain...
Relays will give an option to use resistors that will blend nicely with the rest of your system and with your taste - there's a choice!
I had DACT 50K (SMD resistors) and was never happy with a cold/sterile presentation. Replaced it with TKD motorised pot and never looked back.
ELMA switch (used in DACT) can be wired in a ladder configuration - much better than series.
Any switch, used in ladder configuration with nice resistors, will sound better than DACT
DACT (series) stepped attenuators will emphasise the character of SMD resistors used, which, being SMD - is not going to be pleasant, especially at lower volume settings where there are 20-or-so resistors connected in series in a signal chain...
Relays will give an option to use resistors that will blend nicely with the rest of your system and with your taste - there's a choice!
I had DACT 50K (SMD resistors) and was never happy with a cold/sterile presentation. Replaced it with TKD motorised pot and never looked back.
ELMA switch (used in DACT) can be wired in a ladder configuration - much better than series.
Any switch, used in ladder configuration with nice resistors, will sound better than DACT
Just FYI, I found a solution for my microphonics issue by mounting the PC board on stacks of Sorbothane washers on #6 nylon hardware. I only kept one of the kit standoffs so I could mount a ground lug under it. I ran a ground wire up to the big land on the PC board. There are two washers on the standoff as well but I don't think they contact the PC Board.
Now the NuTube will only ring when I work the selector switch or tap on the cabinet.
I'm really enjoying the sound of the unit now.
Now the NuTube will only ring when I work the selector switch or tap on the cabinet.
I'm really enjoying the sound of the unit now.
I’m sold on these:
Amazon.com: iFlight 12PCS M3X7+4.5 Anti-Vibration Fixed Screws Mounting Hardware Spacer Standoff RC Screws kit with 12PCS M3 Nylon Hex Nut for Naze32 CC3D F3 F4 Flight Controller FPV Racer: Home Improvement
I didn’t need to connect the board ground to the chassis either since the board is connected to the ground of the DC power supply connector. Still debating if I want to splurge on the TKD volume pot—the B1K sounds great with the stock 50k Alps Blue Velvet pot.
Amazon.com: iFlight 12PCS M3X7+4.5 Anti-Vibration Fixed Screws Mounting Hardware Spacer Standoff RC Screws kit with 12PCS M3 Nylon Hex Nut for Naze32 CC3D F3 F4 Flight Controller FPV Racer: Home Improvement
I didn’t need to connect the board ground to the chassis either since the board is connected to the ground of the DC power supply connector. Still debating if I want to splurge on the TKD volume pot—the B1K sounds great with the stock 50k Alps Blue Velvet pot.
Thank you for your input and description of the DACT incompatibility with the circuit.
Please note: I am not an EE minded individual so rely on others to assist in achieving my devices.
I will pass the description onto the EE who is to assemble my B1 Korg.
I have had the DACT sitting without a purpose for a long time, It does not get near my Slagle AVC as a Stand Alone Volume Control, hence I liked the idea of giving it a Purpose in the Korg B1.
A little off topic, which type of circuit will a DACT work in ?
Please note: I am not an EE minded individual so rely on others to assist in achieving my devices.
I will pass the description onto the EE who is to assemble my B1 Korg.
I have had the DACT sitting without a purpose for a long time, It does not get near my Slagle AVC as a Stand Alone Volume Control, hence I liked the idea of giving it a Purpose in the Korg B1.
A little off topic, which type of circuit will a DACT work in ?
Rather than buy a commercial isolator, with the spirit of DIY here is my take on some homemade isolators. Please note the attempt at Pass blue. These are silicon dampers used in keyboards. A few cents apiece. The grids they are mounted on is some plastic screen I had on hand. Some 3mm screws and a stack of four dampers with the circuit board in place along with the tallest component will fit. Hopefully this will help some on vibrations. The two adhesives I found that would work with the dampers I bought are shown in one of the photos.
