Best parts for 45 tube amp

M

martin15560

Member
Hi,
I would like to build the 45 tube amp.
Right now I am considering to buy the Yamamoto A08S (or Baloon) because I heard very good things about it and it is kit so it will be probably easy to build. Is it worth it to buy the kit or if I get the parts and build the clone it will be cheaper? Are there some plans and parts list for it?

On the other hand I know there are much more expansive 45 tube amps (e.g. Triode Lab 45M2 ffx / 45RS-R) so I am wondering if I could do even better than Yamamoto? Do the more expansive amps have better parts in them? Is there some "best" 45 tube amp DIY design? What are the best parts for the 45 tube amp?

And is the difference between $2000 and $8000 amp significantly different?
 
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Well, I'm sure you understand that a 45 amp is only going to output 1.5W to 2W, so super efficient speakers are necessary for any real dynamics or bass. That said, I think the Yamamoto AO8S is a very enticing amplifier and one I would consider for myself. However, I am really not certain that 2W is going to give me powerful dynamics and balanced sound from my Zu speakers even though they are purported to be over 100dB efficient.

Do be aware that dual purpose 2A3/45 amplifiers will not be ideal since the two tubes require different output impedances . The 2A3 is best with 2.5k ohm to 3k ohm load and the 45 needs 5k ohm for the best power to distortion relationship. I wouldn't spend more money than the Yamamoto kit since unless you are really convinced that you can live with the power limitations of the 45 tube it will be a bit of an audio experiment. The Yamamoto will have great resale value if you construct the kit carefully, so if the experiment fails, you can get your investment back.

In a single ended amp (most amplifiers really) the major cost and the primary influence on the sound is the quality of the output transformer. You can buy a cheap Chinese amp and replace the standard components such as resistors, capacitors and tubes with the very best audiophile approved parts and it will still sound mediocre because the most important component is the output transformer. So with the Yamamoto you aren't just buying a well engineered unit as a whole, but a high quality set of iron with a good circuit all wrapped up in an attractive package.
 
If you want to save more and get a well liked design (you pick the best Output Transformers in your budget) check out tubelab.com & he has a forum at diyaudio.com for lots of help.
 
I used the Tubelab board to build my 300B. It can be used for the 45 or 2a3 tube as well with just a few part swaps. The 300B will give you a few more watts. Mine puts out around 6 watts and pushes a pair of 95db speakers pretty well.
 
First directly heated triode tube I ever listened to, was a Marconi 45 globe all cobbled up on a breadboard connected to a Whitely Stentorian HF1016 10" full-range driver in a 3.5 foot cabinet port tuned to around 40-45Hz. I never heard voices and midrange sound so natural...I was hooked from then on.
 
Shadowdog said:
If you want to save more and get a well liked design (you pick the best Output Transformers in your budget) check out tubelab.com & he has a forum at diyaudio.com for lots of help.
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If I decide for Tubelab board are there diy plans for 45 also (or the web is rather for 300B )? I tried to look at the tubelab.com but I won't get in because of antivirus alert :).

And is there some Output Transformers ranking list :D so I know which to choose? Anyway I would probably want to stick around or under the $1000 - $2000 range.
 
The tubelab SE was originally designed around the 45 tubes. I built 2. One with Electra Print iron, the other with Edcor.
 
mkane said:
The tubelab SE was originally designed around the 45 tubes. I built 2. One with Electra Print iron, the other with Edcor.
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Electra Print is better than Edcor? What about other output transformers in comparison e.g. Lundahl or Hashimoto? Is there big difference in sound?
 
Another option to consider is the Bugle 45 designed by Gordon Rankin, especially if you prefer to use point to point wiring (the tubelab SE is circuit board based). It's another highly regarded design. I built a budget version (using scrounged transformers) as my first DIY project. Here's the build article: http://www.wavelengthaudio.com/bugle.pdf
 
martin, in my case there was a big difference. Edcor presented a more laid back sound. EP iron portrays lots of detail. It's my favorite of the 2. I also use better caps. Whether that is where the difference lies, who knows.

I have 50 or so pages that lead you through the build & testing if you're interested.
 
mkane said:
martin, in my case there was a big difference. Edcor presented a more laid back sound. EP iron portrays lots of detail. It's my favorite of the 2. I also use better caps. Whether that is where the difference lies, who knows.

I have 50 or so pages that lead you through the build & testing if you're interested.
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Yes of course I am interested, thank you very much :).
So it is possible to use this design ( or any other ) and if you match the output transformer specification you can use any other transformer instead? Or some transformers are better to use with specific designs than others?

Edit: Would you recommend point to point or board based project?

Edit2: How so there are 45 tube ams with 1.5 WPC and other with 2.5 WPC. Final amp wattage depends on the plate voltage or the wattage of used tubes? Can I have 4 WPC 45 amp or what is the upper wattage limit?
 
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martin15560 said:
Yes of course I am interested, thank you very much :).
So it is possible to use this design ( or any other ) and if you match the output transformer specification you can use any other transformer instead? Or some transformers are better to use with specific designs than others?

Edit: Would you recommend point to point or board based project?

Edit2: How so there are 45 tube ams with 1.5 WPC and other with 2.5 WPC. Final amp wattage depends on the plate voltage or the wattage of used tubes? Can I have 4 WPC 45 amp or what is the upper wattage limit?
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Yes, you can use whatever brand of output transformer you want as long as the specs are close. The specs don't have to be exact.

Point to point gives you more flexibility. If you start with a printed circuit board you're tied to using that schematic. With point to point it's easier to modify the circuit if you want, although it's probably more time consuming. I've only built things using point to point.

Output power is linked to the operating points you choose for the output tubes. Here's the data sheet for the 45.

https://tubedata.altanatubes.com.br/sheets/127/4/45.pdf

SE amps are operated in Class A and you'll see there are a few different suggested operating points listed, each of which uses a different output transformer primary spec (load resistance), different voltages and currents, and they produce different amounts of power. As you can see, the max for this tube is around 2 wpc. If someone is actually getting more than that they are abusing the tube and it won't live as long.

It's important to remember that doubling the watts (output power) only produces an additional 3db, which is noticeable but not a huge increase. It's the equivalent of moving 1m closer to your speakers. It takes 10 times the power output to make something sound twice as loud. So the difference between 2w and 2.5w is about 0.75 db, which I doubt you'd even notice.
 
FlaCharlie said:
It's important to remember that doubling the watts (output power) only produces an additional 3db, which is noticeable but not a huge increase. It's the equivalent of moving 1m closer to your speakers. It takes 10 times the power output to make something sound twice as loud. So the difference between 2w and 2.5w is about 0.75 db, which I doubt you'd even notice.
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Yeah you right, I would maybe try to do point to point design and 2 WPC would be enough but here: http://www.wavelengthaudio.com/bugle.pdf is stated 2.5 WPC even though there is 275V plate voltage and 0.035A current so why is that (is it class A ?) and would I had to make some changes so the tube life is not necessary shorter?

There are probably not some picture building guides for point to point design of 45 tube amp?
 
martin15560 said:
Yeah you right, I would maybe try to do point to point design and 2 WPC would be enough but here: http://www.wavelengthaudio.com/bugle.pdf is stated 2.5 WPC even though there is 275V plate voltage and 0.035A current so why is that (is it class A ?) and would I had to make some changes so the tube life is not necessary shorter?

There are probably not some picture building guides for point to point design of 45 tube amp?
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If he claims a bit more, well . . . the operating points used are the same ones recommended by the data sheet and listed as maximum so he is not operating the tubes beyond normal range. If you wanted to run the tube more conservatively, you easily could.

I'm sure you could find tutorials on point to point wiring, perhaps a video on YouTube.
 
Shadowdog said:
One thing about Tubelab's design is it has SS devices to assist the tubes making it hard to do without a PCB.
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Yup. It has voltage regulators and DC heater circuits. When I had the board finished I used jumper wires to wire up the power trany and output tranies, ect. Even with the populated board and all those jumpers spread all over my bench the thing was dead quiet. No hum at all. I was kind of surprised.
 
Lavane said:
When I had the board finished I used jumper wires to wire up the power trany and output tranies, ect. Even with the populated board and all those jumpers spread all over my bench the thing was dead quiet. No hum at all. I was kind of surprised.
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My experience was the same. I was pretty surprised that it was dead silent with my 99db Altecs. I normally have to track down some sort of hum or buzz in my point to point builds but the Tubelab build was dead quiet from the start. I used electraprint outputs and I am very happy with them.

KC
 
kcdonahue said:
My experience was the same. I was pretty surprised that it was dead silent with my 99db Altecs. I normally have to track down some sort of hum or buzz in my point to point builds but the Tubelab build was dead quiet from the start. I used electraprint outputs and I am very happy with them.

KC
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Supposedly it's just as quiet using the resistor in place of the choke. But I didn't want the added heat under the chassis so I used a choke. I used Transendar output transformers. Too bad he isn't making them anymore. They sound great and were made not far from where I live. One person had Edcore make a power transformer for the Tubelab board. It has an Edcore part number too. So it can be ordered. I used a Hammond that was drop in perfect.
 
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