Lil Knight
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Posts posted by Lil Knight
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I asked Dr Gilmore about that before. Setting the trimpot in the middle would be fine.
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They would work just fine. But i want something that is
compatible with my stack of machined brackets.
Would the PSU has side heatsinks to match the amp or just onboard ones?
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People really want to use HE6's as room speakers and dump 60 watts
RMS into them, this will do the job for sure.
Aww, so would this make the HE6 sound like a speaker from a distant of 12 feet or more?
Need an overkill T2-like PSU too...
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Would the digital attenuator be a separate module (which means I can use it with other builds) or 'fixed' into the KGITSOJC?
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Thanks for the great work, Dr Gilmore!
AFAIK, Ti has suggested some changes. Not sure if this applies with the current one.
- Parallel a 680R resistor and 10k Trimpots to adjust bias and offset, you should pre-set the trimpots such that you measure 500R across them after installing it on the board, along with the 620R or 680R resistor. This would then be the initial power-up setting. (setup procedure using them here)
- A 475 ohm resistor in series with the wiper to the amp board to buffer the board a bit from being shorted completely to ground (volume pot minimum condition) or connected directly to the output stage of the source (volume pot maximum condition).
- Optional (well it's all optional I guess, but this one especially?): Reducing the gain to 7 by changing the global feedback resistors to 1.21KΩ and 200Ω (from 2KΩ and 100Ω) and increasing the feedback compensation cap value from the suggested 33pF.
- Substitute the OP27 for a OPA134PA as it offers much lower DC offset.
- Kevin's schematic showed no input resistor to ground, but the board is laid out for a 10K resistor. If you have a <100K volume pot wired up at the input, then 10K is too low a value. Anywhere from 10K to 1M is more "the norm" for a JFET input amp.
If nobody takes the job, I'm willing to do a small run of boards like last time.
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i'm interested in the Khozmo attenuators, but the unknown is how those switches are going to hold up after years of use
One thing worth paying attention is that, while their pots are great, they don't have a stable design. AFAIK, they've changed the designs on both types at least 3 times.
The very first ones have PCB pins which would fit for your need but later, they no longer did that way. No idea why.
The SMD one even has more stupid design. The wires are pre-soldered to the pot and you have to make sure about the correct length before ordering. Of course you can change the length but that'd require opening the pot.
The Dale one has very stiff feeling and requires a shitload of force to turn the shaft, I couldn't make any step without using a heavy knob. The SMD, however, feels just like the DACT.
Both are huge, maybe about twice the DACT.
Oh, I forgot about the price but it'd be better to leave it to private.
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Woah. Looks hefty. Do you mean both series and shunt versions when you said both versions?
They only have the shunt now. The other one is built by Dale resistors (also has the all PRP version). Hard to say which I prefer, both are beautiful.
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Wow, I missed your post! Congrats! So jealous. Tomorrow is April Fool's so I hope you aren't kidding too soon
Heck, I even went with a cheaper way than yours. I'm thinking of using the Alpha pot that I got from Birgir for the build. Gonna switch to something else later but priority is to finish the amp first.
The pot I just got is Khozmo, SMD version. Got both of their versions and all I can say is perfect. The SMD one, I could say, is the baby RK50. Much, much cheaper but build quality is out of this world. This one will be in the T2 later.
They had some stupid issues back then, but now I think it's safe to buy stuffs from them. Seriously they did a great job to pull back the reputation. So far I already bought 5 attenuators from them, all arrived safe and sound.
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So my struggle continues....more observations below.
Good to hear the PSU is working fine. Did you get the 2SK389s from the the guy 'tubeseller' from ebay? I got some caps from him, all are fine, not sure about other stuffs though.
I already finished populating all the boards and also done with the chassis so hopefully I could catch up with you soon.
Got a stunning looking attenuator today too
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Almost there! (that's what she said.)
I'm curious how the input wiring could make the LEDs keep blinking.
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There's a person on diyA that sells the 2sc3381 at much cheaper price, 2$/ea, if I don't mistaken.
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Material: Aluminum
Dimensions: 4" vertical x 5" horizontal
Number of fins: 17
Perimeter: 61"
Availability: Stock, no minimum order
Cost: ~$150 per 18" length
That are some huge heatsinks. I'm planning for a little different dimension one, 5" H and maybe 3" V. Still haven't decided the style of fins though.
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Happy Birthday, Mr DIY! Have a great one.
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Happy Birthday! Have a great one with your T2.
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A quad deck RK50 for the T2DIY. Every system needs at least a couple of RK50's.... right?
Nice. Where did you get it?
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So what's the problem with your positive rail?
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That burns.
I have a source that sells the K216s really cheap and they all have the long legs like the ones on the right. Thinking of getting a bag of 100.
Is it confirmed that the ones on the left are fake (and the right ones are genuine) ?
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Happy Birthday! Have a great one.
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I'm going to do a small round of the new revised boards, so if anyone is interested, just let me know. This is done with Doctor Gilmore's permission.
A friend of mine is running his own factory that can make PCBs. My last experience with the KGSSHV boards was excellent. I'm going to pick up the boards on my own.
For 2 sets of PCB, price is $245/ea. 5 sets is $195/ea, 10 sets is $155. Plus shipping, plus fee. That's almost the same price like last time but we only need 10 people for the round.
Keep in mind that you have to do the chassis work on your own this time because Doctor Gilmore won't do that tedious job again.
Right now 2 sets are already spoken for. I'm hoping we can reach at least 5 sets.
Also, if anyone is interested, I might be able to help with the back and front panels by acrylic or aluminum. Finish is brushed ,plain or glossy (not really sure about this, will ask my friend again to make sure). Laser engraving and CNC are available. Thickness is up to 15mm.
Custom power transformers can be done but I don't think I will take up that job because of the heavy weight.
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Very nice, Kerry.
Are you going to stack the amp above the PSU like you did before?
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MY counterfeit Nippon Chemi-con 680uF/450V from HKG:
Printed "Negative Black" on the body but no black inked on the negative terminal and original Nippon Chemi-con KMG/KMH has not printed "Negative Black" on the body.
Printed "KMG". The KMG series are the read type and up to 47uF for 450V.
Date Code is "B459"
When peel the shrink cover on the body, the cap has a "X" shape slit on the top. Nippon Chemi-con uses "Y" shape.
Capacitance is OK but I can't trust them to use for the high voltage applications.
http://www.chemi-con...ounterfeit.html
http://picasaweb.goo...286571084384946
I checked for voltage and it's still OK.
I've a big box of high voltage TCI caps but they are 1500uf 500v. I might swap for them later if the Nippons bite the dust.
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They are just some PRP and Takman carbon 0.5W. All sourced from PCX. Some values I bought from diyhifisupply.
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Almost done populating the small parts. One of the 680uf caps failed the measurement, I'm still waiting for another batch. Had to parallel/series some resistors due to the lack of values.
Still can't find #6-32 plastic screws locally
Anyone who has some spare ones and willing to ship worldwide, please let me know. 
Anyone who has some spare ones and willing to ship worldwide, please let me know. 
dynahi rev 2
in Do It Yourself
Posted
How much power does the dynafet consume? I haven't seen many impressions about the dynafet so far.