yeah, the first time I saw the design, the fan threw me a bit...but not having heard the original before, I guess I wouldn't know how loud (or quiet) the fan is. If it works for other people, then I'm sure it'll be fine for me.
One other issue would be that I would like to use balanced connections to allow for future room layouts.
Now how about the basic cost estimate? 🙂
One other issue would be that I would like to use balanced connections to allow for future room layouts.
Now how about the basic cost estimate? 🙂
EvilYoda said:
Leave plenty of room in the enclosure for future upgrades, and the parts cost for 1 channel WITHOUT the final output devices is around 40 bucks. That is with Dale resistors and low inductance / ESR electrolytic caps, Wima, AVX(?) and Silver Mica caps.
1. Tranformer ~ $60-80 online bargain shopping
2. Heat sinks and case ~ $10-1,000 depending on your WAF requirements
3. 2 PCB's and parts ~ $75-100
4. Wire, RCA's, binding posts, IEC A/C input, Fuse holder, pwr switch and such ~ $15-20 bucks from Steve @ APEX.jr (Plug for a good supplier, NO affiliation, just habitual customer) If I were a junkie he'd be my pusher.
5. TIME! That is the biggest cost for "most" builders.
Audiophile approved parts. Dan would be proud. 🙄
I would like to build one up to "reference" standards and compare it directly to the original.
Use 2 - 12 volt DC ball bearing fans and run them at about 4 to 6 volts. Place two flat back heat sinks with at least 2" fins.... fin to fin and blow up through them. 2 fans running that slow still move alot of air and they are really quiet.
Now I have taken all this apart and am placing three output devices per sink (one pair of sinks per monoblock) to see if I can keep dissipation under control WITHOUT any fans...... I need to space the output devices alot further apart than they are on Jan's boards to get this to work though......
Mark
Now I have taken all this apart and am placing three output devices per sink (one pair of sinks per monoblock) to see if I can keep dissipation under control WITHOUT any fans...... I need to space the output devices alot further apart than they are on Jan's boards to get this to work though......
Mark
Attachments
Deleted triple post... how'd the heck does this happen?
Mark
P.S. Help...... I'm stuck in a worm hole........
Mark
P.S. Help...... I'm stuck in a worm hole........
Mark A. Gulbrandsen said:
Prolly me editing my last for too long caused the glitch.
Today I brought a "newbie" to a local shop that has one(1!) dedicated 2 audio room and showed him what "good" sound was.
Cassandra Wilson on a Krell DVD player, Krell Multi-channel pre amp(in a stereo only room 😕 ) balanced to a pair of Classe mono's driving B&W 802"D". Nautilus with diamond domes.
Well He agreed that his B0s3 speakers can't reproduce that voice!
Anyway, the Krell AV pre amp didn't sound that bad, so apparently Dan is keeping current (pun intended).
rabstg said:
Cool...that doesn't seem too bad considering the amps I've been looking at. If nothing else, I could buy a pair of the PCB kits now and get around to the other parts later.
When's the next order anyway?
Evil Yoda,
Post a PM to Mark. I thought his order of 100 boards was coming in.
Now he has to go to Page, AZ to prepare some theaters for BIG SOUND for the new King Kong movie, so he won't be able to do much until he gets back, probably next week.
Remember, Mark is only the source of PinkMouse's boards, and I think Troy is done with group buys for parts, 😀
Lyndon
(with the only working Krell Klone in Utah, 'cause I've got Mark's speaker posts, mwhahawahahahhahaha!)
Post a PM to Mark. I thought his order of 100 boards was coming in.
Now he has to go to Page, AZ to prepare some theaters for BIG SOUND for the new King Kong movie, so he won't be able to do much until he gets back, probably next week.
Remember, Mark is only the source of PinkMouse's boards, and I think Troy is done with group buys for parts, 😀
Lyndon
(with the only working Krell Klone in Utah, 'cause I've got Mark's speaker posts, mwhahawahahahhahaha!)
Ah, so just the PCBs, eh? Sourcing the parts shouldn't be that hard, just time-consuming...maybe I should give it a few days and see what other amps people are building these days.
Thanks either way!
Thanks either way!
EvilYoda said:
My cost estimate is boards & parts.
Boards are ~ $20-30, and the BOM I have for Mouser and Digi-Key will cost you ~ $80-100(shipping included) for 2 channels.
Again, EXCLUDING output transistors.
EDIT: Please take my estimates as that only. I have a habit of under estimating so you may need to tripple them! 😀
I tried that.
"Krell PCBs, cool. Well, I was aiming for valves but I can always store these PCBs on a shelf untill I get bored and have nothing to do."
Some months later I have bought components, boards, transformers and cooling for 4 channels 😀
Yoda,
If U need boards shoot me an e-mail and let me know how many U need. I will be out of town but I should still be able to keep in touch at least somewhat with e-mail... and I'm around tonight still.
I also am taking some boards with cause I have some catching up to do with shipments. The Post Office in Page is much easier to deal with than having to stand in line here in SLC!!
For those thata re not aware..... Boards are still the same price as before. 14.00 each plus 3.95 for Priority shipping for up to 8 in a large envelope and 3% PayPal to the total. Foreign shipment is 9.95 by Priority Mail. I will only accept payment by PayPal, personal check, or cashiers check. Payments myst be in US currency, cashiers checks drawn on a US bank only... no exceptions. I have several foreign cashiers checks that I cannot deposit at my credit union and I refuse to go to a bank and set up an account just for this!
Thanks,
Mark
If U need boards shoot me an e-mail and let me know how many U need. I will be out of town but I should still be able to keep in touch at least somewhat with e-mail... and I'm around tonight still.
I also am taking some boards with cause I have some catching up to do with shipments. The Post Office in Page is much easier to deal with than having to stand in line here in SLC!!
For those thata re not aware..... Boards are still the same price as before. 14.00 each plus 3.95 for Priority shipping for up to 8 in a large envelope and 3% PayPal to the total. Foreign shipment is 9.95 by Priority Mail. I will only accept payment by PayPal, personal check, or cashiers check. Payments myst be in US currency, cashiers checks drawn on a US bank only... no exceptions. I have several foreign cashiers checks that I cannot deposit at my credit union and I refuse to go to a bank and set up an account just for this!
Thanks,
Mark
Mark, thanks for stepping in here so I know who "Mark" is...but after a little more reading, I think the future UCD700 modules might be a little more up my alley as the Dynaudio's tend to be a little power hungry. One of my first concerns was low-efficiency of such a design such as the Krell-kopy 🙂p) and the corresponding low power output.
Thanks again, but it looks like Hypex for me...that or I just buy a damn Proceed and quit all this speculating. 😛
Thanks again, but it looks like Hypex for me...that or I just buy a damn Proceed and quit all this speculating. 😛
Actually the KSA-50's drive my Dynaudio Audience 9's to window rattling levels. The 9's are 89db@1 watt...... Not real efficient!!
Don't forget the KSA-50 does 50 watts RMS into 8 ohms pure class A then goes Class AB to about 75 watts which is the clip point of the stock unit... so its not such a small amp after all. Double those specs into 4 ohms with an adaquate power supply.
Mark
Don't forget the KSA-50 does 50 watts RMS into 8 ohms pure class A then goes Class AB to about 75 watts which is the clip point of the stock unit... so its not such a small amp after all. Double those specs into 4 ohms with an adaquate power supply.
Mark
Hi guys,
I was thinking about the soft-start/thermistor for the power supply, when I realized that I somehow ordered the wrong thermistors; I ordered CL-30 instead of CL-60. From what I understand, the difference will be that at startup, I will have 2.5 ohms instead of 10 ohms after the bridge, and after startup, I will have a higher resistance for the CL-30 compared to the CL-60, due to the CL-30's higher max current, therefore getting a smaller increase in the voltage drop across it. Is my understanding correct? Would there be any problem using the CL-30?
And while I'm on the PSU topic, I seem to remember that someone came up with an idea (I'm not sure who, and for that I apologize, but I couldn't find it again in this thread) to always keep the power on for the main board and drivers, but only apply power to the outputs when the amp is in use (through a switch or a triggered relay). I don't remember if there was any final "verdict" on this idea, hence my question now: would something like that work? It would allow keeping the amp on a sort of stand-by where the outputs wouldn't consume anything.
Paul
I was thinking about the soft-start/thermistor for the power supply, when I realized that I somehow ordered the wrong thermistors; I ordered CL-30 instead of CL-60. From what I understand, the difference will be that at startup, I will have 2.5 ohms instead of 10 ohms after the bridge, and after startup, I will have a higher resistance for the CL-30 compared to the CL-60, due to the CL-30's higher max current, therefore getting a smaller increase in the voltage drop across it. Is my understanding correct? Would there be any problem using the CL-30?
And while I'm on the PSU topic, I seem to remember that someone came up with an idea (I'm not sure who, and for that I apologize, but I couldn't find it again in this thread) to always keep the power on for the main board and drivers, but only apply power to the outputs when the amp is in use (through a switch or a triggered relay). I don't remember if there was any final "verdict" on this idea, hence my question now: would something like that work? It would allow keeping the amp on a sort of stand-by where the outputs wouldn't consume anything.
Paul
JoeyDD said:
Paul,
that would be me.
It works, there have even been commercial amplifiers with that option + option to switch to different bias settings.
The advantage of keeping the front end always online is the greatly reduced warm-up time as it's the little guys that need most time to reach equilibrium.
Compared to amplifiers running on a low bias setting this approach extends the lifespan of the big capacitors, the ones which are costly to replace.
And overall life expectancy of the front end is longer, with exception of the small capacitors.
Requirement however, is having separate powersupplies.
Currents in the front end are in the mA range, and losses in small transformers are low, the cost of running the front end always online would even keep AmpGuru off your back.
On three class A amplifier homebuilds i've done the added switch thing, all three mosfet designs so the separate powersupplies were already there.
Another advantage is the possibility of switching loudspeaker cables with the main amplifier still on, other commercial designs had a mute switch for switching off output relays.
And sometimes it is handy for measuring.
Funny,
you've got all these old country fossiles building American class A power, on the other side of the pond Yanks prefer to construct Euro Hype.
Plenty cubic inches for me please.
I've just done the scope stuff on the front end boards, and heard one front and driver board through a headphone, so far so good.
JoeyDD said:
CL60 resistance is 0.18 Ohms at max rating, it handles 5 amps at 25C.
5*5*0.18= 4.5 watts power rating.
CL30 resistance is 0.06 Ohms at max rating, it handles 8 amps at 25C.
8*8*0.06= 3.84 watts power rating.
time constant and dissipation constant are the same for CL30 and CL60.
CL30 resistance is 0.34 Ohms at 2 amps current.
CL60 resistance is 0.44 Ohms at 2.5 amps current.
Main benefit of the CL60 is the 4 times higher resistance at switch-on.
See resistance table in the STM CL thermistor pdf :
http://www.thermometrics.com/assets/images/cl.pdf
Pagan, does the drawing not state Pre-1983 ? That was the first KSA50, the mark I. The MK-II came after that, more original than the first i think.
