A few years ago I built a VTA ST-120 (tubes4hifi.com) power amp that I am very pleased with. Since then my system has evolved to include two 12" subs in sealed cabinets powered by a Behringer NU1000DSP power amp.
I would like to move that amp to another system in the house leaving me in need of a replacement.
I started reading the Bryston 4B SST clone thread thinking that might be a good direction but after a few pages I feared I would be in over my head. If nothing else, it seems those involved are VERY KNOWLEDGEABLE and at ease with going off script.
So, is there a solid proven design/source for somebody in my position?
A known source for PCB and schematic for a 200w amp?
While I'm a bit of a newbie, having only built one amp so far, I feel I have the right mindset and tools to take on something new.
- I can follow directions
- I have patience
- I am willing to admit I'm over my head and ask for help
- I believe I have the required tools:
Prior to considering DIY I had been looking for an NAD 2200 PE. Current market has them selling for $250-300+ for a relatively decent example. If I am going to spend several hundred I think I'd rather build one; that's why I built the VTA ST-120 in the first place.
It would be fantastic to build something like that Bryston kit but, as I said before, it is seemingly a bit more advanced.
Thanks in advance.
I would like to move that amp to another system in the house leaving me in need of a replacement.
I started reading the Bryston 4B SST clone thread thinking that might be a good direction but after a few pages I feared I would be in over my head. If nothing else, it seems those involved are VERY KNOWLEDGEABLE and at ease with going off script.
So, is there a solid proven design/source for somebody in my position?
A known source for PCB and schematic for a 200w amp?
While I'm a bit of a newbie, having only built one amp so far, I feel I have the right mindset and tools to take on something new.
- I can follow directions
- I have patience
- I am willing to admit I'm over my head and ask for help
- I believe I have the required tools:
- soldering station
- multimeters
- tone generator
- oscilloscope
- variac
- isolation transformer
- and entire woodworking shop, machines, etc
Prior to considering DIY I had been looking for an NAD 2200 PE. Current market has them selling for $250-300+ for a relatively decent example. If I am going to spend several hundred I think I'd rather build one; that's why I built the VTA ST-120 in the first place.
It would be fantastic to build something like that Bryston kit but, as I said before, it is seemingly a bit more advanced.
Thanks in advance.
200w is starting to get out of chip amp range unless you bridge a pair.
they tend to have fewer components than fully discrete amps.
chip amps can be seen as high power op-amps so if you learn op amp theory they are relatively easy to understand.
they tend to have fewer components than fully discrete amps.
chip amps can be seen as high power op-amps so if you learn op amp theory they are relatively easy to understand.
Take a look at this site; audio power amplifier kits @ AmpsLab
I built their Synergy amp ( a dual channel, bass, mid/high), for my E-Drum. Nice amp, and the guy is fery friendly!
I built their Synergy amp ( a dual channel, bass, mid/high), for my E-Drum. Nice amp, and the guy is fery friendly!
Perhaps widen your view to buying a third hand ss PA amp or two - preferably in working order, although having one needing faultfinding could be very enlightening for you. Aim for a PA amp with fault-protection for the speakers (so not too vintage) to give some peace of mind, and with an available on-line service manual. Just testing an ok amp for performance, and that its protection system will save on collateral damage, will be a valuable learning step.
SS PA amps of a few hundred watt are often going for well under $100 on ebay, and basically they often have distortion and noise performance that you would not get close to noticing or even measuring (untill you upgraded your testing kit).
SS PA amps of a few hundred watt are often going for well under $100 on ebay, and basically they often have distortion and noise performance that you would not get close to noticing or even measuring (untill you upgraded your testing kit).
I realize it was a bit of ridiculous question.
I've been watching for pieces from adcom, carver, NAD, and crown.
I've been watching for pieces from adcom, carver, NAD, and crown.
Watch out for Crown DC300. Highly respected in the day for great sound, but designed to produce DC for motor actuators, which can toast your speaker if a zeroing pot loses wiper contact.
Carver strikes me as over complicated to buy broken, & NAD used prices are high.
The best bargains these days are transformer power Peavey stuff from the 80's & 90's. Bands hate them because the transformers weigh a lot and bands set up every night.
CS800x and CS800s have .04% HD and serious speaker protection as delivered. CS800 previous rev C & later can have 4558 op amp upgraded for 4560 for better HD.
The CS800 rev A & B came with a 741 op amp that hissed like a boiler quiet. Plug compatible AD747 or similar products should quiet that circuit right down. These things have a lot of respect from the sound consultant guys over on PA amps forum. Even though a working one usually costs less than $150. Expect wrong output transistors tired electrolytic capacitors and maybe a few wonky solder joints at that price range, but this is diyaudio. You don't want perfection out of the box, do you? I've found you have to dink with the idle bias circuits to get current right, unless you buy the replacement output transistors as a set from Peavey. Also there is the low mileage dog syndrome, where operators made perfect looking solder joints that only worked sometimes. I've found a few of those by watching DC conditions as I poke around and cause the unit to fail. I use a capacitor series speaker (minus to minus) when I'm doing that test, to protect speaker from DC. Even though these speaker capacitors on bipolar supply amps sound funny at high frequency and low wattage.
Carver strikes me as over complicated to buy broken, & NAD used prices are high.
The best bargains these days are transformer power Peavey stuff from the 80's & 90's. Bands hate them because the transformers weigh a lot and bands set up every night.
CS800x and CS800s have .04% HD and serious speaker protection as delivered. CS800 previous rev C & later can have 4558 op amp upgraded for 4560 for better HD.
The CS800 rev A & B came with a 741 op amp that hissed like a boiler quiet. Plug compatible AD747 or similar products should quiet that circuit right down. These things have a lot of respect from the sound consultant guys over on PA amps forum. Even though a working one usually costs less than $150. Expect wrong output transistors tired electrolytic capacitors and maybe a few wonky solder joints at that price range, but this is diyaudio. You don't want perfection out of the box, do you? I've found you have to dink with the idle bias circuits to get current right, unless you buy the replacement output transistors as a set from Peavey. Also there is the low mileage dog syndrome, where operators made perfect looking solder joints that only worked sometimes. I've found a few of those by watching DC conditions as I poke around and cause the unit to fail. I use a capacitor series speaker (minus to minus) when I'm doing that test, to protect speaker from DC. Even though these speaker capacitors on bipolar supply amps sound funny at high frequency and low wattage.
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Keep away from the cheap stuff.
I bought a 1000w amp for a disco as a spare.
I had a look inside and no way is that 1000 watts !
Tiny transformer, tiny smoothing caps and one pair of output transistors.
I bought a 1000w amp for a disco as a spare.
I had a look inside and no way is that 1000 watts !
Tiny transformer, tiny smoothing caps and one pair of output transistors.
Peavey:
I honestly never thought about the Peavey stuff but do recall renting those when I worked in a music store. They do weigh a tone and I suppose very respectable sound.
How loud are the fans?
Carver:
A guy listed a carver amp for sale but then pulled it when he tested and discovered an issue. He originally wanted $50 for it. For $50 it could have been a fun project; either make it better or worse but definitely learn something in the process.
Crown DC300:
I've used those for sound before and remember them having thermal issues. Not even on my radar.
NAD:
It would appear they have become quite pricey as of late. Really annoying.
I am staying away from the cheap stuff.
The most questionable amp I own is a behringer NU1000DSP I bought used for $100. Its the amp currently powering my subs. I want to get that on one of my other systems where the high-pass filter will benefit me.
I honestly never thought about the Peavey stuff but do recall renting those when I worked in a music store. They do weigh a tone and I suppose very respectable sound.
How loud are the fans?
Carver:
A guy listed a carver amp for sale but then pulled it when he tested and discovered an issue. He originally wanted $50 for it. For $50 it could have been a fun project; either make it better or worse but definitely learn something in the process.
Crown DC300:
I've used those for sound before and remember them having thermal issues. Not even on my radar.
NAD:
It would appear they have become quite pricey as of late. Really annoying.
I am staying away from the cheap stuff.
The most questionable amp I own is a behringer NU1000DSP I bought used for $100. Its the amp currently powering my subs. I want to get that on one of my other systems where the high-pass filter will benefit me.
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The Peavey CS800s has a thermally controlled fan board that runs the fan very slowly when I'm using 1/8 W base 70 W peak in my living room. The more primitive early models lack that feature but it could be copied from the s and stuffed in. The circuit is about 5 parts.
It doesn't matter to me. I locate the amp behind a 300 lb Hammond organ with the speakers on stands sounding over the top. So fan noise is totally masked. Couches and record racks can be used to effect to hide away the power amp.
It doesn't matter to me. I locate the amp behind a 300 lb Hammond organ with the speakers on stands sounding over the top. So fan noise is totally masked. Couches and record racks can be used to effect to hide away the power amp.
Maybe build something based on the TPA3255? There a bunch of projects and boards to source here on DIYA. The XRK one seem really sweet. Class D Amp Photo Gallery
Looks like you have everything you need to go the DIY route.
I'd recommend the Honey Badger amp. I built four channels. My Badgers sound very good and they are running 24/7 for a few years now. You can get PCBs from the diyAudio store. There is a great build guide and active threads here on diyAudio.
If you don't like the Honey Badger for some reason (although I can't think of any), there are numerous other amps out there.
The audio circuit and distortion are the same as the CS800s that I own and am very happy with. the power supply is transformer, which is much heavier, and more long lived. (I had to change some e-caps and a NTCR in my cs800s power supply). The DC detect circuit for lifting the speaker relay is op amp and R-C in the x, instead of microprocessor in the s. No reliability penalty to that, IMHO. Some x aren't marked that, but have the grill in the front panel anyway. those tend to be real bargains for .03% HD amp.
Nothing wrong with honeybadger except 150 W/ch instead of 200. Trivial decibel loss. And having to buy case, heatsinks, transformers, switch, IEC socket & speaker connectors, fan, fan control, DC speaker protection board, relays, blah blah at retail price. Best to buy those in a dead used amp "for parts or repair". Or even a working one at $150.
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The power really depends on the "size" of the power supply and on the output transistors used. I guess it should be easy enough to take the Honey Badger to 200W or higher.
I know where I can get a pretty clean and tested CS800x, would require a 260 mile round trip or a Crown Com-Tech roughly a few miles away.
Each are under $135.
I am leaning Peavey but not terribly eager to drive. However, in covid times, what else do I have going on?
Each are under $135.
I am leaning Peavey but not terribly eager to drive. However, in covid times, what else do I have going on?
I'm going to pick up the Peavey CS800X on Saturday. A bit of overkill for the living room, I'm sure.
I suppose its a reasonable choice; sub drivers are 400w 4ohms and amp delivers 420w @ 4ohms. I cannot imagine what would happen to my house if I ever delivered 400w to those drivers.
I suppose its a reasonable choice; sub drivers are 400w 4ohms and amp delivers 420w @ 4ohms. I cannot imagine what would happen to my house if I ever delivered 400w to those drivers.
Work out what your headroom is even with a 20dB peak on a max listening level for your given speaker and room gain. That will keep you busy doing some mental arithmetic whilst driving!
Bought the amp this morning.
Showed up and the guy has about 20 of them on hand. I told him it will be in the living room thus want one that looks clean, he let me look through them all until I found one to test.
Adjusted gain on each channel, no noise.
Played music, sounded good.
I noticed one handle was cracked, he looked around and found a brand new one for me.
Only two things that bug me a bit.
1. I can head that fan. I need to replace it with something quieter.
2. I forgot pro-audio is +4dbu whereas consumer is -10dbv. I had to use additive EQ on the subs to get sufficient output, which I really do not like doing.
Downloaded schematics.
See if I can deal with both issues while not killing myself in the process.
Showed up and the guy has about 20 of them on hand. I told him it will be in the living room thus want one that looks clean, he let me look through them all until I found one to test.
Adjusted gain on each channel, no noise.
Played music, sounded good.
I noticed one handle was cracked, he looked around and found a brand new one for me.
Only two things that bug me a bit.
1. I can head that fan. I need to replace it with something quieter.
2. I forgot pro-audio is +4dbu whereas consumer is -10dbv. I had to use additive EQ on the subs to get sufficient output, which I really do not like doing.
Downloaded schematics.
See if I can deal with both issues while not killing myself in the process.
Wasn’t the Peavey CS800 based on BGW amps from earlier?
If that’s true, the CS800 is likely a decent amp, and not the typical PA amp.
If that’s true, the CS800 is likely a decent amp, and not the typical PA amp.
Just increase R103 fan resistor from 1.5k to 3 k. If the heat sink starts to overheat the sensor will run it full speed anyway. Not likely at 1 w average in a living room.
Or put the amp behind the couch, with longer speaker wires. I use 10 ga 2SO cord from mcmaster.com, the highs sound better than 16 ga on top octave solo piano if you still have your high freq hearing.
You ought to be able to turn the gain down on the X to match your other unit. there is a pot on the back for input volume. Often worn out in used units. I replaced the 2.2 uf input coupler cap too, on my S.
I'm running 120 W/ch PV4 on 13 W max drivers in my TV room. Excess power is not a problem if you don't turn the volume up too high.
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