My current stereo consists of a Pass Labs HPA-1 preamp, a First Watt SIT-3 amp & a pair of Omega Super Alnico High Output monitors (97db 4~6 ohm). While my Roon library has a wide variety of music, jazz & blues are the predominant genres that get played at home. Because I live in a small one-bedroom apartment, high volumes & deep bass coming out of my speakers would make me the neighbor that everyone hates so I avoid both (that's what the Audeze headphones are for). When I built my audio rack in my friend's barn, I left enough room so I could expand the system by adding a couple of tube monoblocks (a stereo amp would be considered as well). I have looked at a lot of nice kits that would be a challenge to build. But since half the fun of stereo equipment is exploring all the myriad options in exhausting detail, I thought I would ask if anyone had a suggestion that might pair well with my current setup for the more demanding option of building from a schematic.
Now that my kids have headed off to college, I find myself at a point where demanding projects that are involved, force me to learn new things and take a long time to complete are a great way for me to spend my time. I'm currently building a small wooden sailboat and I have an old motorcycle queued up waiting to be restored. To prepare myself for this project, I'm reading through Morgan Jones' Valve Amplifiers and Building Valve Amplifiers calculating each of the examples and making my own condensed cheat sheet of the most important points. I'm also reading a lot of information online but that can sometimes be more confusing than enlightening because I still have a lot to learn. Sometimes a particular amp sounds like it would be great but additional research indicates it might not be the best match for my speakers. Nuances like that are not always obvious.
My current criteria is that sound quality is more important than low cost. Complexity is not a deterrent if the quality of the build detail improves the chance for success. I am not set on a particular tube or architecture.
To give an example, as I've surfed around looking at different designs, I came across this one: KT88-based Push-Pull Amplifier
The thing that is attractive about this post is the combination of the schematic with a lot of information that provides additional details about the amp. The pictures of the build along with the layout of the components is a definite plus. But for someone like me who is new to this process, obvious questions like "Are there caveats to switch a design from 220V to 120V or is this fairly trivial?" or "Is this design bound tightly to specific components like the Tango transformers or are there suitable alternatives?" are some of the questions that immediately come to mind. Having a design that can be built "as is" without me having to make any major adjustments would probably be a good idea.
So anyway, I thought I would post details about my specific situation to see if anyone had some suggestions that will help me focus my research on a few good contenders as I move forward. If I ultimately decide to be prudent and go with a kit for my first build, then I'll use these suggestions as options for a later build when I become more proficient. It will still be nice to study the suggested designs for future consideration.
Now that my kids have headed off to college, I find myself at a point where demanding projects that are involved, force me to learn new things and take a long time to complete are a great way for me to spend my time. I'm currently building a small wooden sailboat and I have an old motorcycle queued up waiting to be restored. To prepare myself for this project, I'm reading through Morgan Jones' Valve Amplifiers and Building Valve Amplifiers calculating each of the examples and making my own condensed cheat sheet of the most important points. I'm also reading a lot of information online but that can sometimes be more confusing than enlightening because I still have a lot to learn. Sometimes a particular amp sounds like it would be great but additional research indicates it might not be the best match for my speakers. Nuances like that are not always obvious.
My current criteria is that sound quality is more important than low cost. Complexity is not a deterrent if the quality of the build detail improves the chance for success. I am not set on a particular tube or architecture.
To give an example, as I've surfed around looking at different designs, I came across this one: KT88-based Push-Pull Amplifier
The thing that is attractive about this post is the combination of the schematic with a lot of information that provides additional details about the amp. The pictures of the build along with the layout of the components is a definite plus. But for someone like me who is new to this process, obvious questions like "Are there caveats to switch a design from 220V to 120V or is this fairly trivial?" or "Is this design bound tightly to specific components like the Tango transformers or are there suitable alternatives?" are some of the questions that immediately come to mind. Having a design that can be built "as is" without me having to make any major adjustments would probably be a good idea.
So anyway, I thought I would post details about my specific situation to see if anyone had some suggestions that will help me focus my research on a few good contenders as I move forward. If I ultimately decide to be prudent and go with a kit for my first build, then I'll use these suggestions as options for a later build when I become more proficient. It will still be nice to study the suggested designs for future consideration.
Is this going to be your first build? Did any electronics work before? Read the stickies on safety around valves/tubes.
I always think a simple pre-amp is a good first build (if you are more ambitious than just building a kit). Something with nice sound and almost no gain would be fine, and it could replace the passlabs preamp...
Then later, build something fro your high efficiency speakers - a low powered end stage.
For fun, if money is not a big deal, why not start playing around with the 26 tube? Sure, many would suggest 6SN7 or something like that, but heck, ST 26's are still possible to find for a not-so-crazy price.
DC heaters are really possible to do with a couple of Rod Coleman's boards, and you can try you hand and building a couple of Gyrators. You're in the US, so you can also get pretty decent power transformers from AnTek at great prices too...
Use a good quality stepped volume potentiometer. Don't skimp on that part.
Ian
I always think a simple pre-amp is a good first build (if you are more ambitious than just building a kit). Something with nice sound and almost no gain would be fine, and it could replace the passlabs preamp...
Then later, build something fro your high efficiency speakers - a low powered end stage.
For fun, if money is not a big deal, why not start playing around with the 26 tube? Sure, many would suggest 6SN7 or something like that, but heck, ST 26's are still possible to find for a not-so-crazy price.
DC heaters are really possible to do with a couple of Rod Coleman's boards, and you can try you hand and building a couple of Gyrators. You're in the US, so you can also get pretty decent power transformers from AnTek at great prices too...
Use a good quality stepped volume potentiometer. Don't skimp on that part.
Ian
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It sounds like you're looking for a kit, or at least a well-documented build for which assistance would be available. How about the Tubelab SSE (Simple Single-Ended) Amp?
Tubelab SSE | Tubelab
You can buy the PCB, and I'm sure you could get assistance from members on the Tubelab section of this forum (https://www.diyaudio.com/forums/tubelab/).
Since your speakers are so sensitive (97dB/1W), and assuming you don't have a giant listening room, a single-ended amp making 4 to 8 watts per channel should be sufficient for your listening. I'm also assuming your speakers have an easy to drive impedance curve. But even if they don't, you could configure the SSE with negative feedback to lower the output impedance of the amp, and use a bigger output tube like a KT88. There's even a chart showing suggested output tubes and operating conditions for the design, at Tubes and Applications | Tubelab.
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Tubelab SSE | Tubelab
You can buy the PCB, and I'm sure you could get assistance from members on the Tubelab section of this forum (https://www.diyaudio.com/forums/tubelab/).
Since your speakers are so sensitive (97dB/1W), and assuming you don't have a giant listening room, a single-ended amp making 4 to 8 watts per channel should be sufficient for your listening. I'm also assuming your speakers have an easy to drive impedance curve. But even if they don't, you could configure the SSE with negative feedback to lower the output impedance of the amp, and use a bigger output tube like a KT88. There's even a chart showing suggested output tubes and operating conditions for the design, at Tubes and Applications | Tubelab.
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Sure, that can work too. Nice little 2a3 or 45 amp project perhaps?
But I would still want to pull the passlabs preamp out of the chain.
I appreciate all of the feedback & ideas. This will give me some additional things to research & consider.
I'm in no hurry so I definitely plan on easing my way into this process and doing it correctly. But while I'm doing all of the basics and educating myself, it's always nice to have an idea of what's at the end of the journey. So this post is just me trying to find a carrot to put at the end of the stick. It will be more fun to have a few concrete targets to aim for instead of a vague notion.
I do love my SIT-3! The setup that I currently have works really well for my current location. I'm not looking for a better replacement. I was looking for something that was different to work on while I listen to music each evening. I have projects for outside the apartment but it's also nice to have a few to work on inside too.
I had originally planned to unplug the HPA-1 from the SIT-3 and connect it to the tube amp(s). But expanding the scope of the project to include another preamp and moving the cables from my DAC to one of the two preamps that stays permanently connected to a particular amplifier is an equally viable solution. I have options and a lot of flexibility. At this moment, anything is possible.
As other posters have indicated, your high efficiency speakers give you great flexibility. Also, your signal source is digital and a phono preamp is not an issue.
SE undoubtedly has its attractions, but SE O/P transformers are more expensive than PP stuff.
I'll grind my own axe and suggest you build a triode wired "El Cheapo". The 6 or so WPC are plenty, in combination with 97 dB. sensitive speakers, and the issue of listening level control has been addressed. Jim McShane sells kits of parts, for the project. You add a chassis and magnetics. A complete set of power "iron" can be purchased from Allied Electronics. Edcor's GXPP15-8K will be satisfactory, in the O/P trafo role. If your pockets are relatively deep, price performance champion Dynaclone Z565 O/P "iron" will give you an option for excellence.
SE undoubtedly has its attractions, but SE O/P transformers are more expensive than PP stuff.
I'll grind my own axe and suggest you build a triode wired "El Cheapo". The 6 or so WPC are plenty, in combination with 97 dB. sensitive speakers, and the issue of listening level control has been addressed. Jim McShane sells kits of parts, for the project. You add a chassis and magnetics. A complete set of power "iron" can be purchased from Allied Electronics. Edcor's GXPP15-8K will be satisfactory, in the O/P trafo role. If your pockets are relatively deep, price performance champion Dynaclone Z565 O/P "iron" will give you an option for excellence.
Attachments
I feel like I've looked at hundreds of web sites while researching but this is one of the reasons I posted my question: To find a few more options that I might have overlooked in all of my previous surfing like this one. Thanks!
Transcendent Sound Products
I built Bruce's 300B preamp and it is way beyond all of the FET based pres that I have built, some of them very good.
I built Bruce's 300B preamp and it is way beyond all of the FET based pres that I have built, some of them very good.
There is also the Baby Huey amp, several variations, here on DIY Audio. It's a huge thread and lots of help from folks that have built them. I heard a 6V6 version last summer. I liked it so well that I now have several sets of the circuit boards waiting for build, EL84 and EL34 versions.
Good luck and have fun,
John
Good luck and have fun,
John
Tips from a newbie
It sounds like the original poster is trying to lever himself into this absorbing hobby, in the same as i have been doing the last couple of years.
Doing the reading is essential, IMV, since my goal is to be able to understand and maintain the amps I am building.
Building the final product is the hard part - the circuit can be up and running in a couple of days, with a PCB and a proven design. The case and wiring the controls are the hard part.
Because a preamp needs lots of inputs, switching, and hence signal paths to consider, I am not sure that is a first project.
If you build one of the Tubelab SE’s, you have a tried and tested solution, and masses of helpful support from this site. But most important - all of the major expenses are not sunk costs. If you invest in good OPTs and fair tubes, then that is 80% of the cost, and can be reused in that point-to-point project you yearn for one day.
I made my job easier on my first build - a tubelab SPP (which sounds great) - by buying an old 50’s school PA amp, and recycling the case - i’ll see if I can post a picture.
Another tip is think about a system for managing the spares you accumulate. It is very nice to be organized, and be able to tinker with pieces to hand.
A good soldering iron is essential, as are multiple meters. The simpler first project allows all of these tools to be integrated, and hopefully gets the safety culture into the backbone. But a good healthy shock from an electrolytic is probably best for that ;-/
It sounds like the original poster is trying to lever himself into this absorbing hobby, in the same as i have been doing the last couple of years.
Doing the reading is essential, IMV, since my goal is to be able to understand and maintain the amps I am building.
Building the final product is the hard part - the circuit can be up and running in a couple of days, with a PCB and a proven design. The case and wiring the controls are the hard part.
Because a preamp needs lots of inputs, switching, and hence signal paths to consider, I am not sure that is a first project.
If you build one of the Tubelab SE’s, you have a tried and tested solution, and masses of helpful support from this site. But most important - all of the major expenses are not sunk costs. If you invest in good OPTs and fair tubes, then that is 80% of the cost, and can be reused in that point-to-point project you yearn for one day.
I made my job easier on my first build - a tubelab SPP (which sounds great) - by buying an old 50’s school PA amp, and recycling the case - i’ll see if I can post a picture.
Another tip is think about a system for managing the spares you accumulate. It is very nice to be organized, and be able to tinker with pieces to hand.
A good soldering iron is essential, as are multiple meters. The simpler first project allows all of these tools to be integrated, and hopefully gets the safety culture into the backbone. But a good healthy shock from an electrolytic is probably best for that ;-/
I also recommend looking at one of Tubelab projects. It's more interesting than a kit, and not quite as daunting as starting with just a schematic. I've enjoyed building several of George's amps.
George is getting ready to release an update to his SE board. Here's the link:
After a 14 year run, the TSE must DIE!
Check it out.
Have fun.
George is getting ready to release an update to his SE board. Here's the link:
After a 14 year run, the TSE must DIE!
Check it out.
Have fun.
KT 88 amp overs ultralinier and triode mode
Of course everyone believes the amp they built is the one you want, however I had built these amps a few years ago and put them up in the closet. I brought them down a few weeks ago and liked them so much I revamped my system and added a sub. They are designed by Pete Millitt and sound pretty good to my ears. He has a circuit board available and that’s makes assembly a little easier.
Push-pull KT88 class A amp with "universal" driver PCB
Good luck
Bill
Of course everyone believes the amp they built is the one you want, however I had built these amps a few years ago and put them up in the closet. I brought them down a few weeks ago and liked them so much I revamped my system and added a sub. They are designed by Pete Millitt and sound pretty good to my ears. He has a circuit board available and that’s makes assembly a little easier.
Push-pull KT88 class A amp with "universal" driver PCB
Good luck
Bill
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I saw a question similar to mine on this forum from 2005 where one of the replies had a ring of truth to it:
So I was expecting a variety of ideas and I’ve enjoyed looking at all the new options I was unaware of. I appreciate all of the feedback.
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