Noob looking for some advice

[MrBurd]

Long time lurker that's starting the journey into the sweet tube world with a Tetra phono pre kit from tubecad. Having heard a buddy's tube gear I have the bug. I'm looking into power amp options now, and am a little overwhelmed with the sheer volume of choices. Being a researcher I've come across this 2A3 PP Push-Pull Tube Amplifier 15W Kit (Stereo)_Power Amplifier Kit_Tube Amplifier Kit_Analog Metric Limited - DIY Audio Kit. Does anybody have experience, or opinion on this circuit? My speakers are 96/db, so I don't need a ton of power, but I do like to try to rattle the neighbors windows on occasion.

Any thoughts, ramblings, advice, scolding is welcome.

[costis_n]

No choke, no leica! :P

Classic (linear) power supplies for tube amps are working much better with at least one choke. They make your gear look cooler, too. Here, on this particular kit, they omitted it, possibly because 2A3's cost more...

[MrBurd]

I see. Thanks for the reply. Being that this would be my first power amp build I'd like to go with a known circuit that has a good following, for the sake of help. Would you happen to have a suggestion?

Thanks again,

Matt

[quikie22]

Originally Posted by MrBurd

I see. Thanks for the reply. Being that this would be my first power amp build I'd like to go with a known circuit that has a good following, for the sake of help. Would you happen to have a suggestion?

Thanks again,

Matt

budget? DHT/iDHT? power? Single-ended/ PP?

Lower power / lower voltage (safer) but still sound great

For budget single ended, many like the RH84 and its variants using iDHT pentodes. (6550, KT66/88 etc)

DHT cost more ... eg 2A3 / 300B SE but supposed to sound better


Budget PP - baby huey, red light district, and host of others

[MrBurd]

I'd like to try to stay under $400 completed, if possible. Not having experience with any other that PP kt88's I'm not sure what topology I'm aiming for. This may be the first, but I'm sure not the last build. I'd like something that can drive my 96/db speakers at a good volume, but don't need bloody ears.

I'm open to se or PP. Just wanting to get some glass bottles in my life.

[boywonder]

Costis: The schematic that the O/P linked to has a choke in the PS.....(the kit does not include any iron)

Mr Burd: Do you have a preamp or would this amp need a volume control/input selection?

The PP 2A3 design in your first post will far exceed $400 when you buy the iron (power trans, output trans, chokes) and buy/build a chassis.

The 2A3 is a directly heated triode (DHT), and building a DHT amp is usually more $$ than a IDHT amp that uses EL34's, 6550's, 6V6's, KT88's, etc.

Are you comfortable with doing a point-to-point wiring project or does a circuit board have lots of appeal? (point-to-point is straightforward, but a PCB sure is convenient).

With 96db speakers and a $400 budget, I'd look at Tubelab's Simple Single ended amp. Tubelab George sells the board for $35 or so, and you can use EL34, KT88, 6L6, 6V6, etc. For good sounding budget transformers, check out www.edcorusa.com. There are lots of other great output transfomers around also. Tubelab also has the Tubelab SE, which uses DHT's like the 2A3, 300B, and 45. It is SE fixed bias and has mosfet followers. Again, the Tubelab SE uses DHT's, and will be more costly to build. I have a Tubelab SE 300B as my main amp right now and I'm presently building a 45 version. Either of these designs can produce 4-8W or so depending on tube choice which should be sufficient for your speaks.

There is loads of support here for building both of those designs.

Amplifier Designs

Tubelab - diyAudio

[tomchr]

Originally Posted by boywonder

The PP 2A3 design in your first post will far exceed $400 when you buy the iron (power trans, output trans, chokes) and buy/build a chassis.

Yep... I'm afraid to add up the cost of the 300B amp I've been working on for a while. I bet it's over $1k for a stereo amp. 2A3 won't be much less than that.

Originally Posted by boywonder

With 96db speakers and a $400 budget, I'd look at Tubelab's Simple Single ended amp. Tubelab George sells the board for $35 or so, and you can use EL34, KT88, 6L6, 6V6, etc. For good sounding budget transformers, check out www.edcorusa.com.

The Edcor CXSE-series of output transformers are very good bang for the buck. There are better options out there, but then we start talking >$200 per OPT!

The Tubelab SE or Simple SE are excellent amplifiers. In fact my 6LU8 Spud was heavily inspired by those designs. I think the total budget on that Spud is less than $250. I sounds decent as-is (small OPTs) but if you upgrade it to the bigger Edcor CXSE25-8-5K transformers, it truly sings. I think it would come in a hair under $400 with the bigger CXSE25 transformers.

~Tom

[rmyauck]

Also Tubelab George's Simple PP EL84 amp (17-18W CH) could be built for $400. He may still have the parts kit to go with the boards. I think he was selling them for an extra $65 I think, as all his boards are $35. Edcor has special PP 8K 25 W, ~ 25% UL Output transformers out which would be the ones to get if you were trying to save $ as they are around $60 ea. The Dynaclone Z-565 would be the next choice for a bit more $ ~$80ea.. They are a full bandwidth transformer (20-20K@ 17W) with the 25% UL taps. Don't know what the Edcors are at full power. Triode Electronics and Dynakit.com sells them. Output transformers really affect the sound quality on a tube amp so buy the best you can afford. JJ EL84's are only ~$10ea and are great on high power EL84 PP amps.

I think the links to the Simple PP are broken on his web site so you should email or PM him.

[ChrisA]

Originally Posted by MrBurd

I see. Thanks for the reply. Being that this would be my first power amp build I'd like to go with a known circuit that has a good following, for the sake of help. Would you happen to have a suggestion?

Thanks again,

Matt

Is the goal to learn or to have an amp? If the latter then the suggested Tubelab Simple SE is good. All you do is stuff parts into a PCB. Robots can do that with zero understanding. You will learn a bit more if you have to build from a schematic. You learn even more if you have to adapt a schematic to parts on hand. Cost is roughly the same as the big ticket items are the transformers.

I would suggest building something simple as a first project. A single ended amp built for low power is good and not expensive. Use smaller tubes. Maybe a 6V6GC or even a 6V6 and with smaller 10W size transformers.

later build the bigger PP amp. There are always uses for a small one so the effort on the first amp can be put to use in a bedroom or office later

Take your time and get the mechanical part "right". So many DIY amps look like school science projects with exposed sheet metal and not at all like a finished product.

[rmyauck]

I see on diytube under the Budgie Preamp on the second Sticky down for the "Complete Budgie Preamp" Hammond has nice cast aluminum chassis bases which are easy to drill and punch holes in for tubes etc. If needed that may be a nice low cost preamp too.