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Suggestions for first and last hifi amp schematic please

Hi Y'all,

begging your pardon. I am pretty sure this is not the first thread concerning this topic but regarding hifi-amps i am totally out of my depth and i would like some suggestions from more educated people.

I want to build an all-tube hifi amp for my little apartment but it wouldn't bother me if it could rock bigger rooms to.

I want to keep my 2-way-bass reflex speakers, i like them a lot ever since i put them on spikes.

I listen to rock, classic, pop, right now, i am using a ND304 which is a good amplifier in my book and i can tell a good recording from a bad with my equipment, i am pretty sure my setup is not top notch but good enough for me. The olde NAD needs it's relay replaced every couple of years and after 20 years it would like some quality time, it cut`s out at very low volume. Also i think i already have most of the parts i would need to build a hifi amp.

I have been building guitar amps and reverb units, that was a lot of fun and i ended up with my own designs but of course i copied parts from existing designs. I don't want to go down that rabbit hole when building an hifi amp but stick to something already existing.

It will play music coming from my computer (yikes!) but once this works i of course would need a phono preamplifier.

I think, i would want an EL95 Push-Pull output stage.

So i thought i could pick an amplifier from this list, get the schematic, replicate it and be done with it but i would appreciate suggestions on what to build, before i start.

Some questions: Ultralinear or not?

Single Ended or Push-Pull? EL95 or EL84 or EL34?

I have a big chassis i want to use and i can apply a lot of shielding, is it insane to have the phono preamp in the same chassis?

I would use what i learned about noise suppression from building guitar stuff and apply it if it is not already in the schematic. DC elevated heaters, grounding, layout, etc.

So what would you suggest?
I bought the speakers 30 years ago and they don`t have any factory label anymore. All i can remember is they where manufactured by a canadian brand with three letters and are 8 Ohms. I do not have to turn my 35 Watt transistor amp up much get high volume, i would guess they are rather efficient. In fact when listening from the record player three is plenty loud, i can`t remeber going to four even when having a party. They have a tweeter, a 7" ( i guess, measures 17 cm) and a bass reflex tube in 52 cm * 25 cm * 22 cm housing.
canadian brand with three letters

Assuming your speakers have a typical sensitivity of 85dB/1W/1m, are not a horrible load to drive (they have a fairly smooth impedance curve), and that being in a small apartment means you have neighbors who might object to you playing your stereo at 100dB SPL, I'd agree that a push-pull 'ultralinear' EL84 amplifier should work and would be a good first project.
  • PP UL EL84 typically makes 10W per channel (or thereabouts).
  • Use negative feedback to lower output impedance so it can drive contemporary loudspeakers that are designed to be driven by zero output impedance.
EL84 amp to build? This is a popular question!

There are many worked out designs of this type, listed here in no particular order:

1) Tubelab Simple Push-Pull (SPP). It's a very straightforward design with good documentation. PCB available.

2) Morgan Jones "Beavois Valley" amplifier. PP UL EL84 with a 6DJ8 split-load phase splitter.

3) Eli Duttman "El Cheapo" (actually a push-pull TRIODE 6V6 amp, makes 5W per channel but could be altered to PP UL EL84 without much trouble)

4) Gingertube "Baby Huey" - uses local negative feedback from EL84 screen grids to control grids.

5) John Broskie's push-pull UL EL84 design

6) Stu Yaniger "Red Light District" PP UL EL84 with a LOT of LEDs for EL84 cathode bias.

7) Poindexter's "Musical Machine" was popular for a while. It uses a pair of 6V6GT in triode, so will only make about 5W per channel.

There are also classic designs you can copy, such as the Dynaco ST35 (if you can find suitable transformers).

That should get things started.
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just my two cents.
Base yourself on an amp that has good output transformers, whose circuit is simple, whose tubes are easily found and inexpensive and above all, have fun.
My favorites in your selection, the two grundig NF1 and NF2 and the Klein and Hummel.
one last opinion, avoid rare and poorly documented things.
Thanks for all the suggestions so far. Where i am at now is i want to stick to KISS but i want to use what i already have, too. I do not have UL OT`s but a bunch of EL95 and EL84 output transformers. So as a first start i am building one output channel using two EL95s in push-pull pentode on a prototype board. The circuit i have chosen to try first is from telefunken, maybe i could do better for "hifi" but i have also been wondering how this output stage acts as a guitar amplifier. Will post a picture of my speakers, too. Maybe the brand is ESM and it is not canadian? I am curious what happens if i use one of them whith the attached circuit.
Telefunken 2550 06.jpg
Greetings Horst,

An EL95 P-P amp will only likely give you about 5 watts per channel. I agree with what others have said: an EL84 is a great way to go. The Tubelab Simple Push-Pull (EL84) is a great little amp. Several build threads on the forum. Build it on a PCB, if they are still available, but the schematic is readily available if you fancy a point to point, or turret board build. By the time you have invested all of the work and expense on an EL95 amp you might as well build an EL84.

Cheers, S.
I apprecciate your suggestions and i do not mean any disrespect. I have built single ended EL95 amps for guitar and i like them very much but at home they are way too loud. i turn the speaker attenuator to -20 dB and it is still plenty loud. Of course this is guitar-world and not "hifi" but i am willing to try EL95 push-pull anyway even if it is only good enough for guitar. Just to see how it drives my music-reproduction speakers. Begging to stand corrected but wanted to try this anyway, thinking 5E3 with EL95. I can do this on breadboard equipment and will not ruin the precious stuff i would like to house my record-playback amp in.
Thanks again, general advice is strongly suggesting EL84 push-pull pentode and EL84 push-pull ultralinear. I get that and i have suitable UL output transformers on my shopping list. I am going EL95 push-pull pentode because i have been wondering about this output stage for guitar and because i already have the parts and if it is not working for hifi i will apppreciate EL84s even more. I have been searching the forum and i am thinking i found the schematic for the Tubelab Simple Push-Pull (EL84).


  • SimplePPschem3.GIF
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That's it. In my builds of the SPP, I substituted a 1.5H choke for the 150R 5W resistor in the power supply. It eliminated the last bit of hum. Depending on your B+ voltage it might be better to replace the 270 ohm, EL84 cathode resistors with 300 ohm ones. The voltage gain/phase splitter tube is a 12AT7/ECC81.