I finished my X-BZLS and 5 watt/ch X-SOZ. I am thrilled with the sound quality! They sound amazing, and I have crappy speakers, and I'm running an unablanced source.
Let me know what you think.
http://members.dslextreme.com/users/amplifier/
X-BZLS specs:
Circuit boards from Kristijan Kljucaric
+,- 50 VDC rails
39K Ohm feedback resistor under main board
2 x 10 uf parallel feedback capacitors
Original spec mosfets
Dual 10K Ohm input attenuator
Single 10K Ohm output attenuators on each output
.250" aluminum plate chasis, with panels from frontpanelexpress.com. .5"
mdf top
X-SOZ specs:
Dual Stancor RT-208 salvaged power transformers, 24.5 VAC @ 8A each, primaries parallel, secondaries parallel
+,- 13.8 VDC rails
CLC filter, 43,000-2mh-43,000 (inductors are x-over filters, seem to work,
but do get hot)
2 x 10K parallel feedback resistors
2 x 220 uF parallel lytic feedback capacitors
IRFP048 mosfets
Outputs to ground = 4.9 VDC
I'm not an electronics tech, nor do I have training, so any advice or constructive criticism is welcome. I may be way off base with my X components, and those are subject to change.
Next project: Horns!
Thad
L.A.
Let me know what you think.
http://members.dslextreme.com/users/amplifier/
X-BZLS specs:
Circuit boards from Kristijan Kljucaric
+,- 50 VDC rails
39K Ohm feedback resistor under main board
2 x 10 uf parallel feedback capacitors
Original spec mosfets
Dual 10K Ohm input attenuator
Single 10K Ohm output attenuators on each output
.250" aluminum plate chasis, with panels from frontpanelexpress.com. .5"
mdf top
X-SOZ specs:
Dual Stancor RT-208 salvaged power transformers, 24.5 VAC @ 8A each, primaries parallel, secondaries parallel
+,- 13.8 VDC rails
CLC filter, 43,000-2mh-43,000 (inductors are x-over filters, seem to work,
but do get hot)
2 x 10K parallel feedback resistors
2 x 220 uF parallel lytic feedback capacitors
IRFP048 mosfets
Outputs to ground = 4.9 VDC
I'm not an electronics tech, nor do I have training, so any advice or constructive criticism is welcome. I may be way off base with my X components, and those are subject to change.
Next project: Horns!
Thad
L.A.
Banned
Joined 2002
Thanks for the complements. This was my first amp project, and I was afraid that the 5 watt output might not give much volume, but I was surprised on that note. I now want to build some kind of Horn, which one, I dont know. I like the Lowthers, but I prefer the price point of the Jordan used in the J-Low. What would the consequence be for me to use a 4 ohm speaker like the Jordan. I beleive that I am pushing my power supply pretty hard, I think I have a total of 392 va's.
Yes, the caps are about a half inch taller than the chasis. Its dangerous!, I will fab a perferated plat top soon.
After 2 hours running, they are hot, but I can leave my finger on them. I'm going to borrow an infrared temp. gun and sample a few select points on the amp, I'll let you know.
Yes, with the exception of the front/back panels, I designed and fabbed both units, I have two shops (machine/wood) at my disposal. I have a chassis just like the preamp slated for a D/A convertor.
kilowattski said:
Yes, the caps are about a half inch taller than the chasis. Its dangerous!, I will fab a perferated plat top soon.
Duck-Twacy said:
After 2 hours running, they are hot, but I can leave my finger on them. I'm going to borrow an infrared temp. gun and sample a few select points on the amp, I'll let you know.
eLarson said:
Yes, with the exception of the front/back panels, I designed and fabbed both units, I have two shops (machine/wood) at my disposal. I have a chassis just like the preamp slated for a D/A convertor.
Hardware for pots and switches
Hello All,
Could you chappies please let me know where you get those nice rods and bearings to operate switches and pots (traditionally at the rear of pre-amps) from the knobs (traditionally at the front of the pre-amp!)
The response I have received whenever I have asked for items such as these at electronics shops is a befuddled silence and a look of pity. I don't even try to explain about short wire runs for better quality sound, because the the pity usually evaporates into mirth.
Regards,
George.
Hello All,
Could you chappies please let me know where you get those nice rods and bearings to operate switches and pots (traditionally at the rear of pre-amps) from the knobs (traditionally at the front of the pre-amp!)
The response I have received whenever I have asked for items such as these at electronics shops is a befuddled silence and a look of pity. I don't even try to explain about short wire runs for better quality sound, because the the pity usually evaporates into mirth.
Regards,
George.
Re: Hardware for pots and switches
The knobs are made from 1.75" O.D. stock 6061, with a hand polished finish. I surfaced the two output knobs and turned the input selector and attenuator down to 1.1875".
The rods are .250" stock ground stainless, I cant remember the flavor.
Ground rod is not necessary, but is what I had available. The rod and rigid shaft couplers are available from McMaster-Carr
http://www.mcmaster.com/
The .250" shaft couplers are oversized for DACT parts, so they are shimmed with .005" bronze, it took about 3 layers.
One of the coolest parts on my preamp are the bearings! I was going to use overkill bronze flanged bearings until I found something perfect for this application. "Spyralign" bearings from Small parts Inc.
http://www.smallparts.com/products/descriptions/pbxd.cfm
They have an excellent action, and can be improved with lithium grease, I used some heat sink grease. They were slightly loose with the precision ground rod, (another argument against ground rod).
GeorgeBoles said:
The knobs are made from 1.75" O.D. stock 6061, with a hand polished finish. I surfaced the two output knobs and turned the input selector and attenuator down to 1.1875".
The rods are .250" stock ground stainless, I cant remember the flavor.
Ground rod is not necessary, but is what I had available. The rod and rigid shaft couplers are available from McMaster-Carr
http://www.mcmaster.com/
The .250" shaft couplers are oversized for DACT parts, so they are shimmed with .005" bronze, it took about 3 layers.
One of the coolest parts on my preamp are the bearings! I was going to use overkill bronze flanged bearings until I found something perfect for this application. "Spyralign" bearings from Small parts Inc.
http://www.smallparts.com/products/descriptions/pbxd.cfm
They have an excellent action, and can be improved with lithium grease, I used some heat sink grease. They were slightly loose with the precision ground rod, (another argument against ground rod).
steenoe said:How hot does the poweramp run?
I cant help thinking those heatsinks looks a bit small.
Steen
Thanks Steen,
the heat sinks are some salvage extrusion I found. They were two long pieces, which I cut off to make the fet sinks. The resistor sinks get hot, but not too hot to hold. The mosfet sinks get real hot, I'll be keeping my eye on those. This weekend, I am going to energize the power amp with a variac and make some temp measurements.
coils said:
I'm very interssted in the temp of the coils. I also have some 2.2 mh coils planned in the CLC ps of my alphe5. I always presumed they would only get moderately warm. However if the get really hot (> 50 celsius or so), I may have to reconsider the way I have planned to build them into the case. They dont have much breething space, like this:
pic1
pic3
pic2 (the "finished" amp is not mine)
They are planned in a square space about 5 cm high with a 2 mm alu plate on top. Above that are the pcbs, below the elco's. There is a 5 mm wide opening at the sides and a lot of open space below (where the caps will be). The 2.2mH tritecs are 3.5mm^2, R is 0.24 ohm.
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