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Credit to tubes4hifi, preamp kit, modified to a single stage buffer / pre.
Changed out to Jantzen cap, toggle for bias adjustment, and a bit of woodworking to match my then speaker build. Separated power transformer from line-level.
Here's one channel of the Pass F6 kit I built a few years ago. I realized I never took a photo of the finished amp. That will have to wait until I get the listening room back in order.
https://diy.midwestaudio.club/discussion/1675/another-amp-project#latest
Southwest Technical Products Corporation (SWTPC) sold computers and amplifier kits back in the 70's. I bought a pair of SWTPC model 207A amps, also known as the "Tiger .01's" They were given this name because IM distortion was said to be less than 0.01 percent at the full 60W RMS power output from 20-20KHz. My older brother Steve assembled and soldered the kit for me. When done, I took the amps to the annual McIntosh amplifier clinic, hosted by Flanner and Hafsoo's, and they easily made the 60W RMS output from 20-20kHz at less than .01% IMD. I can't prove this, however, because I lost the distortion plots that the McIntosh techs gave me many, many years ago.
They worked well and sounded great for years and years. Up until 2009, when, all of a sudden, during a moderate power playback session, one of the two front panel power meters "pinned" hard right. One-half of the full B+ power rail was sent to my 12 inch woofer (44 volts DC). I quickly jumped out of my listening chair and hit the power switch!!
Needless to say, the T0-3 style power output transistors had blown. So I re-built the amp with new capacitors, resistors and power output devices. Should be good for another 35 years! I think Dan Meyer, founder of SWTPC, would be proud!
Bill
Do all my tube amps and preamps count? How about my class D builds? Recent guitar adventures? One of these days I'm going to finally build a LM3886 chip amp. I've had all the parts to do so for years.
I'd like to see em!
There much of a reason why amps such as the SWTPCs couldn't be cloned? NLA components?
F5
This one is a XRK board. It's basically a LSA Warp 1, but this board has pffb, where the warp 1 does not. I built the enclosure for this guy.
Arguably the sweetest non-tube amp - and more accurate- Very Nice!
Thank you. Can I ask why there are two tube sockets with tape over them on your amplifier?
Full schematics, circuit board layouts, parts lists, etc., were published in Radio Electronics Magazine back in the 70's. Some of the original transistors types are NLA, but you should be able to find substitutes. For instance, this amp used obsolete RCA 40409/40410 driver transistors with integrated heatsinks. I was able to find substitutes for these when I ordered parts several years ago. Not sure if you could get all the necessary parts today. But that is one of the challenges of restoring old electronics: Finding good quality substitute parts.
Not that I want to derail this, but I've always been very interested to DIY an amp. What you guys think would be a good bang for the buck that can get decently loud?.... say roughly around 50watt/channel 8ohm. Suspecting those chip amps are currently the king? I've already got some lower power amps that supposedly have the tripath chips, but haven't even used em much. Need something with a little grunt.
Bass guitar amp. Uses the ICEpower 700ASC/X power module. Preamp transformer is AnTec AS-05TC200
I am using it as a single stage pre-buffer (keep it simple) - subsequent to my miniDSP which I employ as an active crossover between woofer and upper frequency set-up (be it a broad ranger or a mid/tw passive setup). The upper frequency signal is fed through this tube unit then to an amp, base goes directly to the amp https://legacyaudio.com/products/view/powerbloc4
The buffer has an attenuator that I can adjust from time-to-time if I want a bit more or less in the low end relative or mid/tw range.
Great builds everyone! That F5 is super clean.
I found some photos of a few tube pieces I built for other people 20 years ago. They obviously had a lot more money to spend on Hifi than I did at the time.
This might have been an SRPP 6DJ8 with a separate power supply. Not my design, just my constuction.
This is a 45 amp - a TriodeDick design. A whopping 1.5 watts! I don't want to know how much those transformers cost.
More photos here - http://www.edsawyer.com/audiogallery/hifitom/
This monstrosity was a 12b4 preamp with a multi-tapped output transformer hand wound by Dave Slagle. The power supply had mercury regulator tubes and timers for the heaters & B+.
My gainclone
Started with an Ikea cd storage box (LOL)
Ripped the front off, added some reinforcement to the various faces.
Put some cherry veneer on:
Everything fits up to the LM3886 boards
Used some ApexJr heat sinks mounted external, with the LM3886 boards attached internally
Came out really nice!
Very sweet and clean sound. Can really pump some watts without strain (distortion)
Tom, would that connector on the top be carrying the full B+?
I built a couple of those myself back in the day. I also built a pair of their Tigersaurus amps. They are all long gone. If yours still have the Tantalum blocking cap on the input you should replace it with a bipolar film cap. Tantalum caps are a short when reverse biased. I blew up a Tigersaurus with the turn off thump of a DIY preamp one time.
https://worthpoint.com/worthopedia/swtp-tigersaurus-amp-amplifier-model-137067042
Ron
Before I did DIY speakers I built a lot of DIY electronics. I've built Dynaco tube amps and preamps, Heathkit test equipment, several DIY amps from magazine articles, DIY op amp preamps and active crossovers. I don't do as much now because it's gotten so inexpensive to buy of the shelf and all the local parts are gone. I still have some of builds laying around but wasn't into documenting them back then.
I built 4 Leach Double Barrel amps from plans in Audio Magazine in 1980. You could order the circuit boards from the magazine but everything else was DIY. They can do 270 watts into 8 ohms and the PS is +/- 85 volts. I repurposed some old instrument cases from the local college surplus store.
This is a picture of the circuit boards and heat sinks going together in the early 80's.
I still have all 4 amps but I'm don't currently have a use for them. One of them died after sitting idle for a long time. When I turned it on it blew the 8 amp fuses between the PS and amp. It's just sitting on the shelf gathering dust now.
This is a picture of some active crossovers I built for a band a long time ago.
Ron
If you are asking about the Speakon on the preamp power supply, yes. B+ and DC heater supplies.
Chipamp
Sorry, I should have been more specific. I meant the white insulated connectors on the top of the big glowing mercury regulator tubes. I think they put the high voltage plates on the top of some of those old tubes to prevent internal arching. The 807 tube amp that I am getting ready to restore has this configuration and I need to be very careful to keep my fingers at a safe distance (and one hand in my back pocket)!!
Oh yeah - ceramic anode caps. Some of those old transmitting and medical device tubes run at crazy high plate voltages, so I guess that's the best place to bring the B+ in. Those 394As are rated for 1250v at 640ma and can handle over 20A surge currents.
An 807 amp - cool! I have had all the parts for a Blueglow Electronics 807 amp waiting in the wings for far too long.
That's REALLY COOL, I'm a real fan of the meters, and the wood knob !
Back in the late 70's I built a Dynaco PAT-4 preamp and ST-400 power amp for a housemate. I charged him a 12 pack each. That become the house system along with a pair of EPI floor-standers and a B&O linear tracking turntable. College audio nirvana.
And I thought my rates were low!
Work on a Nelson Pass AB100 amp right now, 2 x mono,
Are those resistors mounted proud of the board attached to the heatsink?
Alright I'm going to have to play too. Currently diving wallet first into a (hopefully frugal) basic chip amp build to get my feet wet.
Sofar these guys seem most reasonable I can find for terroidal transformers:
https://antekinc.com/
Yeah, that's what I used, most are very affordable.
The one I used was $40 on eBay.