EL84 DIY Amp Project, Part 6 (Conclusion): Sonic Evaluation and Output Mode Options

"Heath" (the prototype amp) at left vs "Hammond" (our patron’s amp) at right

DIY EL84 Project: Part 6

Sonic Evaluation and Output Mode Options

By Steve Graham


A Tale of Two Amplifiers

A recent post on one of the DIY electronics forums was, in my opinion, very observant.  The poster basically stated that “DIY’ers want something for nothing.”  Sorry to burst your bubble, amp builders, but a decent amp costs considerably more than nothing.  If you want performance to rival good commercial amps, money must be spent.  Sure, I’ve lucked out a few times over the years and gotten old tubes and transformers for free, or nearly free.  But modern performance almost always requires modern parts.

The total expenditure for the amplifier our patron chose, shown on the right above, with taxes, parts and shipping included, totaled $1,116 Canadian dollars.  Roughly $850 in US funds.  Our patron sprung for the upgrade tubes, transformers and Mundorf capacitors, but not the dual input or volume control options.  On a tight budget, you might spend an even grand (in Cdn $) for a basic, though still worthy amplifier.

Even at a little over one thousand dollars, I’d happily bet that this amp would rival commercial units costing three to four times this amount.  Enough yakking, you want to know how it sounds.

Review System

For full details of my system, click on the link to my Finalé Audio F-7189 II review from last year. Essentially, it’s a Lumin D1 digital player/streamer and a set of Spendor D7 speakers with the ‘amp du jour’ between them.


Audition tracks:

This is Us, from All The Roadrunning, Mark Knopfler and Emmylou Harris (CD rip)

It Never Entered My Mind, from The Legacy Prestige Sessions, Miles Davis (MQA Tidal)

Prince of Darkness, from One Size Fits All, The Nylons (16/44 Tidal)

Computer Age, from Trans, Neil Young (16/44 Tidal)

I Feel It Coming, from Starboy, The Weeknd (MQA Tidal)

Caravanserai, from An Ancient Muse, Loreena McKennitt (CD rip)

Don’t Make Me Wait, from 44/876, Sting and Shaggy (MQA Tidal)

B Minor Waltz, from You Must Believe In Spring, Bill Evans (24/192 LP rip)

You Must Believe In Spring, from You Must Believe In Spring, Bill Evans (24/192 LP rip)


Yes, I know, I’m a musical gourmand.


Though not all in-house at the same time, at least two of the following EL84-based amps have been chez Graham at any one time:

-My DIY Dynaco ST35 clone with original Dynaco output transformers

-Finalé Audio F-7189 II (review link above)

-Tubelab SPP with ancient Heathkit transformers (my prototype)

-Tubelab SPP with new Hammond transformers (our patron’s amp)

Audio memory is notably fickle, but having at least the Dynaco based design and the SPP prototype as constants allows a ranking to be established.  Go back to Part 1 of this series, to read my impression of the ST35 clone vs. the prototype SPP.


My ranking so far:

Dynaco ST35 Clone – OK

Tubelab SPP prototype with reclaimed Heathkit transformers – Better

Finalé Audio F-7189 II – Better still, by a fairly large margin compared to the ST35 clone.  Even though not in-house at the same time as the SPP proto, I’d still rate the Finalé as the top amp so far.  It had a memorably smooth yet very clear treble that impressed.  No other EL84-based amp has equaled or exceeded that quality in my experience.

So, where does the new-build EL84 our patron commissioned fit in?  Let me tell ya, this was one fun and very instructive listening comparison.

The prototype amp, let’s call him “Heath”, and our patron’s amp, we’ll call him “Hammond”, were set up at the same time and warmed up for about half an hour.  I played a track or two with one amp then switched over to the other and repeated the same track(s).

First off, the initial impression is that Hammond had a more extended and detailed treble.  This is a double-edged sword.  Sibilance heard in Ms. McKennitt’s vocals are somewhat off-putting on a brighter amp, compared to Heath’s less pellucid treble.  It’s not the fault of the amp.  Hammond more clearly delineated the stringed instruments and percussion played on the McKennitt track.  As I recall, the bell or triangle at about the six-minute mark of Caravanserai, was smoother, but also clearer when I had the Finalé Audio F-7189 II here.  

I find the analogue tapes made in the 1950’s and 60’s, transferred to high bit-rate digital, a revelation.  Those, what we would now call minimalist, recordings have a life and urgency that in my opinion, modern recordings don’t or can’t emulate.  Could it be that those old analogue tapes digitized to 24/192 are more musical to our ears than a modern recording made at 16/44 or even 24/88?  The trumpet in the Davis track just seemed brassier, and the whole of It Never Entered My Mind, sounded more achingly beautiful when Hammond was on amplifying duty.

When The Nylons track Prince of Darkness was played, my wife remarked on how vocals seemed clearer and more believable.  All voices inhabited their own bit of space more precisely and believably with Hammond.

Computer Age from Neil Young came through with less annoyance and weirdness on Heath.  I like to play some of the tracks on Trans, occasionally.  It’s mostly so out of character compared with anything before or since from Young.

I Feel It Coming, the Weeknd track.  Not really to my taste but decently-enough produced for a “pop” track.  I dislike the use of hand claps as a percussion instrument in many recordings of this genre.  I find it gets old very quickly and becomes the audio equivalent of a slap in the face with every clap.  Here Heath with its, by comparison, slightly rolled-off treble made it less annoying.  Is it too much to hope that the guitar hero will come back into fashion?  Both amps followed the bass line very well.  ‘Followed’ is perhaps a disservice to them.  I didn’t find that bass lagged at all.  Both amps were quite propulsive at the low end of the audio spectrum, with Hammond slightly better in this regard.

Speaking of guitar heroes, the indefatigable Mark Knopfler just keeps chugging away.  The sound of his left fingers sliding on guitar strings was almost startling with Hammond in the system.  If not right in the room, it was easier to imagine him on the other side of a control room window.  Hammond more clearly unraveled the typical three guitar lines in most Knopfler songs.  From about the 3:35 mark of This is Us, the sort of tension and release, call and response if you will, of the guitar as the song segues into the piano closer was just more gripping with Hammond in play.

Don’t Make Me Wait from Sting and Shaggy:  A fun track that will give your woofers a workout.  I can’t say that I listened to this track all that critically.  It’s the sort you just groove along to, if it speaks to you.  But the seemingly quicker transients of Hammond gave the bass better attack.

Finally, the Bill Evans tracks, B Minor Waltz and You Must Believe In Spring.  Cleaner, more involving and just plain better with Hammond in the system.  Ripped to 24/192 from an LP, ticks and pops were more apparent through Hammond, but worth it for the better overall sound, especially piano.

I haven’t said much about bass response.  Neither amp will give you the sort of buttoned-down bass grip and control that a Bryston, even a small one, provides.  That being said, both amplifiers had sufficient bass extension and woofer control that I didn’t flag either as being deficient in this regard.  Mind you, Spendor D7’s, in my experience, don’t demand a lot of amplifier effort to wrangle their woofers.  The bass seemed a bit deeper with Heath, but I think it wasn’t really the case.  With Hammond in the system the bass was a shade faster.  This speed extended across the audio spectrum.  My conclusion is that Heath’s slightly rolled-off treble made its bass seem a little bit deeper.  The speed of Hammond gave it the bass edge that Heath couldn’t quite match.

The Heathkit-transformered prototype has a bit of the so called classic, tube amp attributes that I find not-so-appealing of late.  It’s not bad or unlistenable, but just sounds a bit mid-20th century compared to modern tube amps.  Heath would make a great amp for a garage or workshop system.  You’d still stop what you were doing from time to time and listen when a favourite track plays.

The patron’s Hammond-transformered amp is, to my way of thinking, a modern tube amp, and worthy of duty as a main amp or even an only amp.

In comparison to my memory of the Finalé Audio F-7189 II?  I’d give the Finalé the slightest of edges over the Hammond-equipped SPP.  Hammond still has a way to go to match the smooth high treble detail of the Finalé amp, if my audio memory can be relied on.  The Hammond-transformered SPP should mature a bit more with time.  The Finalé has some very yummy Mundorf silver-oil caps (to the tune of about $200 dollars’ worth retail!) that might be giving it the edge.  Who can say?  But if I was building another Hammond-equipped SPP, a set of NOS Russian K40-Y PIO caps would be worth trying.

Is the Tubelab.com SPP amp I built for our patron a great amp?  No, in the wide spectrum of all things audiophile it’s not great, just very good.  And that’s more than good enough for about a grand in Canadian money.  It won’t give the likes of ARC, VTL or VAC anything to worry about.  If you have the ability, and enough free time to invest some sweat equity, a very fine audio component will be your reward.  And the price, though not cheap, will be worth every penny.

Fifty years from now someone might pull our patron’s amp out of a closet.  Maybe it will sound a bit antique by the audio standards of 2070.  Many of us won’t be around then, but if Erik stashes away an extra set of tubes, a niece or nephew might just have found a “classic”, that with a little TLC will provide more years of listening enjoyment.  Maybe she or he will “write” it up as a Classic/Heritage/Exotic on the direct-connect brain web.


Thanks ever so much to our patron Erik.  His leap of faith made this series possible.  I hope he isn’t let-down when the amp settles in to his system.  I think it’s a keeper.  I hope Erik agrees.

My photo studio, aka the laundry room

For those interested in configuring this amp for pentode or triode, use please see the attachment.  I haven’t actually tried these myself, so “YMMV”.

Part 6, Attachment 1: Pentode and Triode Connection Options (PDF link)



Review Rant (sort of):

This has been a fun and instructive project, but I’m burned out.  Technical writing isn’t difficult. Making text interesting and good grammar usage isn’t a priority.  There’s just so damn much of it with a scratch-built project of this scope.

So that’s me done.  After a line stage, a phono stage and now a power amp there’s not much else to do.  Don’t anyone suggest speakers, I’ve had enough woodworking for one lifetime.

I don’t plan on doing a more powerful amplifier.  The bigger the amplifier, the bigger the pitfalls, in my estimation. The best advice I can give someone wanting to build a more powerful amplifier is to look at the Elekit TU-8340VK that I built and reviewed a couple years back.

If the DIY itch needs scratching and a single-ended amp appeals, visit the Tubelab.com website.  There are two single-ended boards available.  One using pentodes (EL34s, KT88s etc.) and another running 300B tubes.  There’s also a Tubelab forum on Diyaudio.com.


I’m not giving up on tube-based DIY.  I have a couple of projects on the go and more in the planning stages.  They’re a lot more fun when I don’t have to write about them.

To join the tube DIY community, try this link:  https://www.diyaudio.com/forums/tubes-valves/

If you think building this amp might be something you’d like to tackle, skim all of the attachments in every part of this series before deciding.  Sure, there are many pages of instructions, but a big job is just a whole lot of little jobs stung together.

Good luck to potential amp builders.  I’m passing the torch, the soldering iron actually, to you.  Don’t grab the hot end. 😊


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4 Comments on EL84 DIY Amp Project, Part 6 (Conclusion): Sonic Evaluation and Output Mode Options

  1. Steve Fink // 2020/02/25 at 6:25 pm // Reply


    We need many more photos of the lovely Miss K !!


  2. I’m working on it. While you’re waiting try the link below. Miss K will be especially pleased if you build a tube amp.


    Thanks for your interest in WOS.ca

  3. Cameron Godecke // 2021/12/30 at 3:10 pm // Reply

    I have a Dynakit with Dwve Gillespie’s EFB fixed bias PSU upgrade. Makes a VERY significant and needed improvement to the tiny amp’s drive and overall sound quality. Still, the tubelab circuit looks interesting for some Eico HF-81 OPTs I have. Gotta love EL84 amps!


  4. Andrew Black // 2023/04/18 at 7:53 pm // Reply

    I have just completed this Tubelab SPP amp build. I cannot emphasize enough how valuable Steve’s guidance was. The instructions and pictures were very clear and helpful. I used Steve’s schematic for a pentode build as my Fisher OPTs were not suitable for an ultralinear amp. After experiencing hum during my first sound test, I switched the OPT primary wires exactly as Steve recommended and the problem disappeared. This amp sounds wonderful and I cannot thank Steve enough for sharing his deep knowledge of this subject.

    Andrew Black

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