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The Cavalli-Kan Kumisa III Stereo Headphone Amplifier has landed - Page 4

post #46 of 75
Quote:
Originally Posted by cotdt View Post
Why does the amp cost $300 to build? You can build a Dynahi for less than $300.
This must be a misunderstanding! I have built mine for less than $150 with quality parts plus an quite expensive enclosure (at least above average).

You can get a kit for the CK²III from jrossel for ~$70. OK, you still need to add things like enclosure, knop, wires... ect, but the total cost will probaby in a range of $100 - $150: very reasonable for an amp like this (assuming DIY).
post #47 of 75
Quote:
Originally Posted by Xeno7651 View Post
For the guys who own the CK2III, what's the gain setting on yours and what cans have you tried the CK2III with?

I want to compile a list of cans that the CK2III drive well so that I may try them with the amp in the future. For me so far, it works well with the K701s, PX100s, and UM1s.
I use mine with a RS-2 and an W1000. I find the gain setting to be a bit high for these low impedance cans. The knob is about .20 for normal listening and .30 is quite loud. The next time I build a CKKIII I will change the gain according to the amb.org build suggestions. The amp sounds great with these headphones however. I really enjoy it.
post #48 of 75
Quote:
Originally Posted by Ferrari View Post
You can get a kit for the CK²III from jrossel for ~$70. OK, you still need to add things like enclosure, knop, wires... ect, but the total cost will probaby in a range of $100 - $150: very reasonable for an amp like this (assuming DIY).
Yup, I spent $140 building mine using the suggested parts + neutrik locking jack + knob etc. All resistors are Vishay Dale, caps are WIMA or panasonic. High quality components, but not boutique components. It sounds amazing, especially considering the cost.
post #49 of 75
Quote:
This must be a misunderstanding!
Yes... the assumption that I built and shipped those "two amps" for free would be a major misunderstanding.
post #50 of 75
Thread Starter 
Quote:
Originally Posted by MisterX View Post
Yes... the assumption that I built and shipped those "two amps" for free would be a major misunderstanding.
No doubt. You have to pay for quality parts and workmanship. I have no complaints.
post #51 of 75
Quote:
Originally Posted by Zoide View Post
How does the CKKIII compare to the beta22? I know the beta22 is much more expensive to build, but parts cost doesn't tell the whole story.

BTW, there has hardly been any coverage of the beta22. I agree that the DIY amps haven't been given the attention they deserve as of late.
they sound COMPLETELY different. the Beta22 uses output MOSFETs while the CK²III uses output BJTs. Beta22 uses a mild amount of negative feedback while the CK²III uses none at all. They are both very good amps with wide bandwidth and low output impedance (0.01ohm for the Beta22 and 0.4ohm for the CK²III for audio frequencies). Despite being a "little" amp, the CK²III actually has quite a lot of voltage swing and output power, and can easily be configured to drive the K1000 in Class A. The Beta22 measures better than the CK²III in every category so it is technically better, but in listening tests it will depend on the listener whether the Beta22 or the CK²III is preferred.

Here are my impressions using the Denon D2000 as headphones. First of all, on my setup with my discrete output Zhaolu and everything wired in silver, the CK²III is not laid back at all, but a little on the forward-sounding side. I think most would describe the amp as neutral in regards to forward/laid-back. The amp's gain is set to 4.1x (lower than default) and the quiesent current set higher than the default at 45mA. The Beta22 is much fuller and warmer, with a larger soundstage and is a little more laid back. The CK²III is more detail-emphasized since it has more treble, and is much more forward sounding. Some may think the CK²III is more involving because it has an intense forward midrange, but the Beta22 is less fatiguing for long listening periods and more "euphonic" because of the warmth and fullness. The sound of the Beta22 is quite unique really, of the amps I've heard only the Dynahi has a similar sound signature. Both amps have very fast attack and tight bass, but the Beta22 emphasizes the low-end more. the Beta22 is not the kind of sound one typically associates with solid state amps, while the CK²III is brighter so I guess you can associate it with solid state. to me, the CK²III is a significant improvement over the Dynalo. It is more transparent. CK²III actually sounds very similar to my tube amp, and listening casually I would not be able to tell the difference.

The Beta22 is far bigger physically than the CK²III, and much more expensive. I mainly use my CK²III because it is only 1/3 the size of my Zhaolu DAC while the balanced Beta22 is too big to fit anywhere near me.

I think the CK²III's true competitor is the M^3 since they are around the same price range, but I think the CK²III is slightly cheaper and quicker to build (not sure since I've never built the M^3 myself, but I've heard it several times). The CK²III only takes about two casual afternoons to build the entire amp. M^3 is more laid back but the CK²III is more lively, and I prefer the CK²III. CK²III is purely discrete and has higher bandwidth, while the M^3 measures lower distortion. M^3 uses a lot of negative feedback, which a lot of people say is bad.
post #52 of 75
Quote:
Beta22 uses a mild amount of negative feedback while the CK²III uses none at all.
While it is true the CK2III does not employ global negative feedback it does feature local feedback, in fact that is how the gain is set.
post #53 of 75
Quote:
Originally Posted by MisterX View Post
While it is true the CK2III does not employ global negative feedback it does feature local feedback, in fact that is how the gain is set.
in that case wouldn't ALL amps be considered to have feedback? not very useful term...
post #54 of 75
Quote:
in that case wouldn't ALL amps be considered to have feedback?
Nope.
Tunnel diode amplifiers (for one) do not require any form of feedback whatsoever.



Quote:
not very useful term...
It was your point to begin with ...
post #55 of 75
lol i never even heard of tunnel diode amplifiers... must build one...
post #56 of 75
Hello MisterX,

What is the gain (Av) of the Kumisa III in the current configuration? How does this perform as a line preamplifier?

Thanks,
routhun
post #57 of 75
I just wanted to post a thank you to those involved in creating this great amp. I recently built one from one of Jeff Rossell's handy little kits. It took about four evenings after work to get it up and running. I've only built a cmoy previous to this so I'm sure those with more experience could have done it in half the time.

I wasn't completely thrilled with the sound at first, the details and seperation were lacking big time. I thought maybe it needed some burn-in time but after a week it sounded the same. I did some searching and found a thread on the β22 I believe and read about the output transistors and the different sound characteristics. This link (discrete diamond buffer - parts list) is what help me decide to try the 2238 and 968. Finding them was a different matter. I finally ended up ordering some off of ebay thinking they were probably knock-offs and hoping I wouldn't damage the amp with them. 2 1/2 weeks later they arrived. I made the switch that evening and fired it up and happy to say, smoke free! I let her warm up, readjusted the trimpots, doulble checked the voltages and plugged in. Guess what? Bingo!! There was that WOW feeling I was looking for! A whole new beast had awakened. The details, the seperation, tight bass, it was all there.

I can't say for sure if the transistors are knock-offs or not, but I am completely satisfied with the end result. This amp combined w/ my Senn 580's is exactly what I was listening for.
post #58 of 75
Zigzag, glad you're enjoying it now! I was recently reading about some other guy who found it fantastic only after replacing the input JFETs with BJTs. Out of curiosity, how many milliamps of QC did you tune your original transistors to? I quite liked the amp at the suggested bias w/HD650s, but it's really blowing my mind now that I've pushed it to ~50mA!! Perhaps it's all in my head.

Cheers
post #59 of 75
I kept them to the suggested 30ma. Same w/ the new transistors. I should probably order some heatsinks and try cranking it up a bit but I'm pretty happy with it right now. One thing I did notice and read about is the varying voltages and how the h/s help minimize this.
post #60 of 75
Quote:
Originally Posted by zigzag View Post
One thing I did notice and read about is the varying voltages and how the h/s help minimize this.
Oh like you wouldn't believe. At first I had 4 individual heatsinks and it was tough keeping it around 30ma--drift was crazy etc. Then I chopped up a massive heatsink from some vintage equipment and when I brought it up to 50ma it was not only rock steady, but if it drifted, the qc would only decrease a bit! I'm posting pics in a week or so once I get a few finishing touches on it. (Front panel from frontpanelexpress.com -- really neat service) Anyway, transistor rolling sounds more and more appealing now, guess I should've installed transistor sockets!
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