I'll have to dig into the book to get the detail, but that was the general test setup. The tubes were set up in a circuit for minimum distortion (active loads if I remember correctly.) There were also tests of distortion differences between standard circuit blocks (resistor loaded triode, SRPP, mu-follower, etc.) but in a whole amplifier, that would be a separate test of the amplifier itself.
The point of the test was to determine if the 6SN7 lives up to it's reputation as being a very low-distortion device. He tested a wide variety of tubes that claim to conform to the specs of a 6SN7, including loctal types and 6J5 variants. He concluded that yes, the 6SN7 does deserve its reputation, but along the way way he found that specific types of 6SN7s exhibited lower distortion than others. The winner was the carbon-coated glass variety, specifically the CV1988. (He also suggests the reason for this.) Among the 6J5s, the Russian Pinnacle GT exhibited the lowest distortion, while the older shoulder-shape varieties had higher distortion.
Tubelab's TSE is not a beginners project and multiple multimeters are needed. Since you're looking at the TSE I assume low wattage is fine? <10W Single Ended?
Edit: Oops. I thought tamra's post was LeifB60's for some reason. I would recommend once again a tube preamplifier mated with a solid state design. Getting around the expensive output transformers for your budget is a challenge.
Pete Millet's Engineer's amplifier with Edcor or Sacthailand transformers is the best for the price if a tube amplifier must be it. With the cost of everything and the chassis, it adds up.
Edit: Oops. I thought tamra's post was LeifB60's for some reason. I would recommend once again a tube preamplifier mated with a solid state design. Getting around the expensive output transformers for your budget is a challenge.
Pete Millet's Engineer's amplifier with Edcor or Sacthailand transformers is the best for the price if a tube amplifier must be it. With the cost of everything and the chassis, it adds up.
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It is possible to build a very nice tube amp with your budget. Key is to spend on the output transformers, but if you look at the 'cheap transformers' thread, there seem to be lots of options at this time in Europe.
If you budget €250 for OPTs, another €120 for power transformer, €100 for tubes, that would give you good quality and a rewarding basis for an amplifier. Then there are various PCBs on offer here (e.g. Tubelab) and apart from the satisfaction of building yourself, you will have the confidence to maintain the final product.
Softone has good reputation and not expensive OPT and possible to use both SE and PP, enough for 300B.
I recommend firstwatt amps.
Once build good PSU in 4U400 chassis,you can change to F4,F5,F6,M2,Aleph J or even SIT amp easily.
I recommend firstwatt amps.
Once build good PSU in 4U400 chassis,you can change to F4,F5,F6,M2,Aleph J or even SIT amp easily.
The OP asked for an amp not a kit.
Used Dynaco SCA35 fisher or similar is available at that span. A Braun 2X12 w is available at Tradera
combined with a CE16 tuner for 7900 SEK https://www.tradera.com/item/170613/655695095/braun-csv13-braun-ce16-dieter-rams
Used Dynaco SCA35 fisher or similar is available at that span. A Braun 2X12 w is available at Tradera
combined with a CE16 tuner for 7900 SEK https://www.tradera.com/item/170613/655695095/braun-csv13-braun-ce16-dieter-rams
The Elekit TU8500 or TU8550 preamp could be a great option. Yes, it’s a kit, but it’s relatively safe to build, as there’s no need for biasing and no exposure to high voltage once it’s complete. It’s one of the best ways to achieve a tube sound, though a preamp won’t have the characteristic tube glow.
Unfortunately, finding a fully built tube amp within the desired price range is quite challenging. Anything vintage would likely require restoration.
Unfortunately, finding a fully built tube amp within the desired price range is quite challenging. Anything vintage would likely require restoration.
At that price level, I think tube power amplifiers will blow your budget for any significant power output. Hammond push pull output transformers alone start at over $100 USD each for a 10W audio output transformer.
Recommendation: solid state Class AB or D power amplifier with a tube front end. My personal preference is a simple subminiature common cathode triode DC coupled to a cathode follower. Medium mu 6814, 6021, 5718, 6N16b. Subminiature tubes sound excellent, and they are a bit oddball, so they are cheaper. They can be directly soldered (no tube socket) to a PCB or perf board. Kits/PCB Gerbers available? I am not aware of any. This is diyA. Pretty easy to design your own, and there is plenty of help here.
Like this Audiophile DIYer preamp. He doesn't offer this any longer, but this is the form. A palm sized tube preamp.
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Making Your own / diy - chasis is pain in the axx - either you but prefabricated product and open holes & other openings as needed for which You need to have some good tools or You make drawing in CAD ( or some similar software ) and then send that to the chasis manufacturer who wants to do one-off job.
Many buy prefabricated boxes from China/ Italy / Germany / local and then proceed with their own tools and one that is needed for precision opening of the holes is drill with stativ ( excuse me don't know english expression ), then there are big rectangular opening for transformer windings ( if needed, depending on the design ). This can be done with hand-held drill but very carefully and with other tools.
The amp could be "closed" design, everything inside the chasis - but this i would never do, regardless how many slots the box has because the tubes will heat everything inside and eventually could cook the motherboard ( if such exists ) - this from personnal experience with commercial EL84 PP amp.
So add the chasis to major costs beside transformers.
If interested just to look here's the link to french site with many projects and all of them ( or most ) have ready files for chasis maunfacturing among other files like pcb's etc, just translate to english when open the page :
https://novotone.be/projets
Alternative way of making Your own chasis with U profiles and plates is given by Morgan Jones - Building Valve Amplifiers 2nd edition, available on the net in pdf format and if You're gonna find this then find also Morgan Jones - Vlave Amplifiers, 3rd or 4th edition or both.
There is altenative route to diy - finding second hand amp of good quality, service as needed and then see where the manufacturer cut corners and improve or just improve if possible ( this requires a lot of knowledge ). Depending on the exact design / implementation changes can be limited.
Many buy prefabricated boxes from China/ Italy / Germany / local and then proceed with their own tools and one that is needed for precision opening of the holes is drill with stativ ( excuse me don't know english expression ), then there are big rectangular opening for transformer windings ( if needed, depending on the design ). This can be done with hand-held drill but very carefully and with other tools.
The amp could be "closed" design, everything inside the chasis - but this i would never do, regardless how many slots the box has because the tubes will heat everything inside and eventually could cook the motherboard ( if such exists ) - this from personnal experience with commercial EL84 PP amp.
So add the chasis to major costs beside transformers.
If interested just to look here's the link to french site with many projects and all of them ( or most ) have ready files for chasis maunfacturing among other files like pcb's etc, just translate to english when open the page :
https://novotone.be/projets
Alternative way of making Your own chasis with U profiles and plates is given by Morgan Jones - Building Valve Amplifiers 2nd edition, available on the net in pdf format and if You're gonna find this then find also Morgan Jones - Vlave Amplifiers, 3rd or 4th edition or both.
There is altenative route to diy - finding second hand amp of good quality, service as needed and then see where the manufacturer cut corners and improve or just improve if possible ( this requires a lot of knowledge ). Depending on the exact design / implementation changes can be limited.
Beautiful top plates can and should be done... However, you will spend epic amounts of weekends gathering measurements, creating cut-out macros and suffering over the layout in the CAD tool. First photo is an 845 SE amp of mine, my first top plate - lots of time spend measuring everything, printing out parts of it on paper to make sure holes line up. Took a year to get there. Second photo is a Lynn Olson Amity Clone mini-monoblock. Same CAD tool and Front Panel Express, took a month to layout. Third photo is a top plate I designed for my cabinet maker friend who helped me out with woodworking, took a weekend to layout. None of these top plates cost more than $200 in mill fees - and it was all done by uploading files to a mail order CNC milling shop!
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If you want the sound of a good tube amp rather than something to show off to your audiophile friends, the little JLH 10W Class A amp will provide this at much less $$$ and effort. I've tested it in DBLTs and it is the only amp with fairly high THD (about 0.1% near overload) preferred to supa low THD amps.
Loadsa info on this including the huge thread on diyAudio for substitute modern transistors etc, and many kits from eBay too.
There are several updates, some from JLH himself. I think only those that allow direct connection to the speaker without an output capacitor are worthwhile. But the one I tested in DBLTs was the original.
Also likely to give better sound is to use a SMPS instead of a huge conventional PSU. This will improve the sound of practically ALL Class A amps. You could use several computer laptop PSUs in parallel.
Use the biggest heatsinks you can afford / fit in your space.
Loadsa info on this including the huge thread on diyAudio for substitute modern transistors etc, and many kits from eBay too.
There are several updates, some from JLH himself. I think only those that allow direct connection to the speaker without an output capacitor are worthwhile. But the one I tested in DBLTs was the original.
Also likely to give better sound is to use a SMPS instead of a huge conventional PSU. This will improve the sound of practically ALL Class A amps. You could use several computer laptop PSUs in parallel.
Use the biggest heatsinks you can afford / fit in your space.
JLH amp is a great choice now in the cold northern hemisphere. Nice room heaters. Are there heatsinks big enough?
Class A triode tube preamp for H2 into an ultralow distortion Class D amp that can drive any speakers.
Class A triode tube preamp for H2 into an ultralow distortion Class D amp that can drive any speakers.
Yes, I would start at around US$1500 for a decent new 30-40 watt integrated tube amp. You could also buy a good used unit for that price. You might check your local used hi-fi web sites.