DIY Loudspeakers: HOME  INDEX  UPDATES  RESPONSE  WHAT'S NEW

EAR 861 Power Amplifier
Copyright 2017-24 © Troels Gravesen

go to: EAR 861 2019

I've been looking for a small high-quality tube amp for my workshop, meant to operate with my Hypex Ucd amp for bi-amping. As my Hypex amp is working fully balanced and has input attenuators, something similar would be nice for amp supposed to run the midrange-tweeter drivers. Now, having these demands really points to a very few amps on the market except for PA amps, where these features are common - and always solid state or digital. Not what I was after, rather something like my GlowMaster.

Some EAR power amps have these features and being happy with my EAR-912 preamplifier I might give one of the power amps a try. Doing the usual google study reveals quite a few positive reviews and I was lucky finding a nice looking and "non-smoking" amp on eBay. I've bought used gear before and given a current retail price of 7000+ EUR for a new amp, which is a crazy price for 32 wpc, I took my chances - and was lucky. The amp is like NOS despite being 11 years old. Based on the looks of tubes and circuit board, this amp has had very little use and no need for tube replacements.
Later I was able to buy 2nd hand mint condition line stage, the EAR-868L, which is a perfect partner for the EAR-861. The EAR-868L has double balanced outputs and besides the usual SE inputs a single pair of balanced inputs. The line stage itself is similar to the EAR-912. And it has a remote! Just what I needed for my workshop system.
Having had this system now for 1½ year (late 2018) I don't think I'll ever get rid of these two components*.
*Actually I did replace the EAR-868L with a new EAR-868PL.

Here the EAR-861 description found at Needledoctor website:

Push-pull power amplifier operating in pure Class A, enhanced triode mode. Zero overall negative feedback. 32 wpc stereo (bridgeable to 64 watts mono) into 4, 8, or 16 ohms. Uses EL519 output tubes. Self-biasing. Balanced and unbalanced operation.

After years of research, development and day-to-day manufacture with the EL519 series of pentode tubes, Tim de Paravicini has come up with a new and exciting Triode configuration. Conventional triode connected pentodes have the second grid tied to the anode, which results in a halfway compromise between a pentode and a triode. This neither has the efficiency of the pentode, nor the linearity of the triode. Tim de Paravicini's Enhanced Triode Mode (ETM) goes one step further, and creates a true, highly linear triode from a robust pentode tube.

Instead of driving the normal Grid One with signal, this is tied down to the cathode, and thus becomes an invisible, transparent element, and part of the cathode. Signal is fed into the tube's Grid Two, and in this configuration, Grid Three has no effect - it can either be connected to earth, or left floating. The ETM behaves like a true triode and is in fact more linear than the majority of directly heated triodes. Compared with the latter, it has the additional advantage of being a tough, more robust tube, capable of much longer operational life.

The first amplifier to use the ETM configuration was the '859, and with some justification the '861 could be regarded as a push-pull version of the '859. However, this is more than a slight understatement: each output transformer has a massive 5 kilogram weight, with no feedback applied around it. The circuit is balanced push-pull from input to output, allowing balanced (professional-style) inputs as well as conventional unbalanced (RCA phono jack socket). Similar to the '859, the circuit is direct-coupled. Tube choice is not critical; perfect operation does not rely on matched tubes, nor on user adjustable bias.

Output power is 32 watts per channel, 20 Hz - 20,000 Hz. The half power bandwidth is in excess of 16 Hz - 60,000 Hz, both with low total distortion, and no overall feedback. Tube complement: 2 x ECC83, 6 x PCC88 and 4 x EL519. Amplifier weight: 27 kilograms.

Subjectively the amplifier has the same 'family' sound as the EAR 859. Listeners will find it builds heavily upon this, with an increase in authority and attack. The lower bass has real grip and feel with this amplifier, way in excess of the 32 watt power rating while the treble is smoother, cleaner and sweeter, mainly due to the lack of overall feedback. A single word can sum up the 861: ''effortless.'' It has real power and control, the power to convey the emotion of the most demanding of recordings, whether the source be our preferred analogue or digital.

First thing I did was measuring the gain of the power amp to be able to align the gain of my Hypex modules of the ATS4-HE speakers. I cannot understand why manufacturers are so reluctant to state the gain of their products. So much needed.

The measurements here were done on the 8 Ohm taps and with an 8.2 Ohm resistor across terminals. 24.6 dB average gain is excellent. Only need to tune down the Hypex modules by 1.5 dB. So done, overall low-end balance is perfect.

I didn't expect the EAR 861 to be a sonically fully compatible with the GlowMaster, but it turned out not to be that simple. The GlowMaster had an edge in far field ambience and overall resolution of dynamic complex material and maybe we're down to the difference in power, where the GM excels in dynamic head-room. It does have twice the power of the 861.
This 861 amp is kind of "annoying" as my standard tweaking tool-box seems to run short. I mean, orange-drop polyester coupling caps against VCap CuFT... Which points to the fact that there are more to tube amps than just a couple of coupling caps. The 861 does have an enticing ability to bring us close to the music and let us forget about subtle details.
What stands is a magnificent sounding power amp with more than enough power to run the mid-tweeter of the ATS4-HE and similar constructions, thus an ideal partner for bi-amping*.

After a few weeks of use with a variety of speakers I've come to like this amp even more. What strikes me the most is its ability to drive low-efficient, 4 Ohm speakers from its 8 Ohms taps. For some reason it doesn't sound as good from the 4 Ohms taps.
It's simply amazing the drive and punch this amp can deliver**.

Only flaw I can point to is the inscription on the top plate: "TECHNOLOGY AT IT'S BEST!". First of all you don't put an exclamation point on an amplifier! And the error of using an apostrophe in "IT'S" is hard to believe from an English product. Had it been Chinese... Even with my limited English skills it should be "ITS". I guess EAR have had hundreds of these made as it is found on several amplifiers. Bottom line is you don't have to brag about an amplifier like this. I know, "it ain't bragging if it ain't lying", as Americans would say, but still...Given the current 861 retail price it's like Rolex adding "TIME AT ITS BEST" on their 10 kUSD watches. Bad taste!

*: Replacing the coupling caps with Rike cupper foils caps did the trick. Not an easy tweak due to size! See below. I don't think this amp gets much better.

**: Having had the 861 for some months now I'm surprised over and over again on how this amp can run speakers like the Ekta mkII, the ATiRi and not least the most recent FUSION. None of these speakers are in what I reckon as high-efficiency speakers (92+ dB range). Well , the FUSION is around 89-90 dB and 861 runs the 12" bass driver with slam and firmness. Not like the Hypex Ucd400, but so close I ran the FUSION for long before I even considered bi-amping. 

In Danish we have the word "rør-slæde", which means tube-sleigh. This is what it is.
Beauty is in the eye of the beholder, but I love the design of the EAR 861.

I use the amp on its 8 Ohm tabs, even for 4 Ohm speakers like the SBA-MTM. By the way, a very good combination. I often have the question from tube amp users which tab to use with a given speaker. The answer is easy, you try out both and hear what sounds the best. There is no right.

Rock-solid chassis from 2 mm steel plate.
I've added some new feet, 17 mm height, to be able to get my fingers under it.

Click image above to view large

8 x 330 uF/250 volt capacitor bank.

These orange capacitors are likely to be changed to some better ones, but as-is, this amp sounds darn good. Actually tried inserting four super-caps (double-lane metallised PP) - and surprisingly this wasn't for the better, so the orange drops went back again. The super-caps made a slightly aggressive top and no apparent improvement in transparency. Hmm....
Having transformer coupled line stages I shorted the input caps (red circles above). See schematics below. No need for potentially degrading caps here. I fully understand EAR's concern for people having DC coupled pre-amps. If something can go wrong, it will.
Another thing would be bypassing the input potentiometers and switches. I tried shorting the potentiometers and it did not make any change at all regardless of several recommendations. Most of the time the amp runs with minimum attenuation and i reality the potentimeter is just a contact point. I doesn't make any difference.

Analysing the schematics for possible bottlenecks can be hard. The obvious coupling capacitors between amplification stages are the usual suspects and possibly the 100k anode resistors, although I'm highly skeptical about the latter. So, I made a cautious investment in four 0.68 uF Mundorf tin-foil capacitors - and then things finally started moving in the right direction. Bass and mid as good as it gets, only the treble range - despite being very smooth on the ear - leaves some far-field ambience to be desired. Not much, but significant compared to my GlowMaster. Next I by-passed the tin-foil with 10 nF Silver/Mica caps from my former riaa-stage, and although I don't believe this makes any difference, it sounds darn good! So, either the micas or my brain i doing the job.
Next stage in testing is four Rika copper foils caps.

Now, these Rike caps are huge! Fortunately we have lots of space in the 861 and the solution was to add two bars next to the tube row and mount the caps as seen on photo. The caps I got from Rike were not the same "packing", which was kind of a disappointment, one pair was in tubes, the other with standard wrapping. Nevertheless, having the bar some 60 mm above the circuit board, there is just enough space for the caps, having a diameter of 50 mm! Length is 35 mm. This size caps doesn't allow placement between the valves.

These Rike caps are a serious alternative to VCap CuFT caps and close to 25% of the CuFT. 238 EUR/four compared to 297 $/ea. What the Rike caps produce compared to tin-foil/silver-mica is the far-field ambience I have from the GlowMaster. This doesn't mean the two amps sound exactly the same. The 861 has some triode character, slight midrange emphasis. There's nothing soft or tuby about the 861 sound. Clear transparent midrange and shimmering highs. The ability to run low-impedance speakers from the 8 Ohms taps is amazing! It runs my most recent Ekta mkII, ATiRi and FUSION speakers to loud levels without trouble or apparent distortion. Mission accomplished.

Above and below: Talking to an EAR guy at Munich it was also suggested trying the Audyn Copper Max caps. So, 4 x 680 nF were bought at HifiCollective, UK. Now, this time I would omit the support mounted on the circuit board and made four brackets attached to the corner bolts of the transformers. A brass bar was added and the caps secured by straps. Actually looks a bit nicer than the Rike solution.
I can't say this sounds any different from the Rike caps, but they're cheaper and are easier to implement - provided the support is made. The Copper Max stays in. I don't see any reason experimenting any further on this tweak.

Power transformer.

OPT.

Should you like the 861 so much you buy two, the amps can be bridged to make 64 watts. 

1. Connect BAL input cable to left channel.
2. Set mono/stereo switch to mono.
3. Turn left channel level fully clockwise.
4. For 8 Ohm speaker: Connect the two 16 Ohm tabs and connect speaker to "0" and "16" Ohm tabs.
5. For 4 Ohm speaker: Connect the two 8 Ohm tabs with wire and connect speaker to "0" and "8" tabs.
6. For 2 Ohm speaker: Connect the two 4 Ohm tabs with wire and connect speaker to "0" and "4" Ohm tabs.

The manual includes these handwritten schematics.
This is not fully identical to the product I have, but it may give an idea of how Tim Paravicini designed the 861.
Click image to view full-size.

Schematics as found in manual. As mentioned above, the input capacitors (0.47uF/100V) were by-passed . Actually they are 1 uF.
Also the driver stage appears significantly changed compared to this simplified draft.

EAR 861 2019

I've been more than pleased with my second-hand 2004 EAR 861 over the last 2 years. It's reliable, quiet and has the neutrality - to my ears -  and transparency I was aiming at. Considering the price of two new EAR 861 amps I was thinking of alternatives like the Nagra Classic Amp, which I've heard on several occasions in Munich, and which impressed me very, very much. A totally different ballgame going from PL519 tubes to a 100 wpc class AB solid state, but these Nagra guys apparently know what they doing. Now, I can't have a Nagra for testing in my living room. I don't even think there is such an amp in Denmark. Would the Nagra give lower noise and transparency? Maybe lower noise - after all - but the sound? Considering all the components in my system, the EAR 861 is not the bottleneck except for power for some low-efficiency speakers. It has everything I want, so why change?
Thus, two units were ordered in order to run them in bridged mode making 2 x 64 watts - and my current reference speaker, the Ellipticor-3s, with their "sine-cap" 2.9 Ohms minimum impedance just love it! Wiring the 861s in balanced mode for 4 Ohm just works fine (se above).
 

The new EAR 861 looks exactly the same as the 2004 unit I have.

And yet, the silly - and misspelled - "Technology at it's best" has been erased from the top plate! Nice! Thanks!


Removing the top plate and turning it around I found this: "TECHNOLOGY AT ITS BEST".
Apparently EAR had the plates re-printed on the other side :-)
Maybe suitable for some markets... "It ain't bragging if it ain't lying".

No change to the rear panel at all.

The el-cheapo polyester coupling caps have been replaced by some blue polypropylene caps - and I think they sound better.
Setting up the new 861 next to my old - and modded - 861 made me a bit uneasy as the difference really wasn't that big.
Time will tell if my by-passing the input capacitors and replacing these blue PP caps with Miflex copper foil caps will take it even further.

PSU bank of capacitors have been replaced by 220 uF/400 volts (the old caps were 330 uF/250 volts).

The circuit board has the same stock number as my 2004 version, EAR 861-3.

Left: Shorting the input capacitors with jumpers. If you do so, be absolutely sure your line stage is AC coupled, not DC!
Right: Coupling caps removed and pieces of wire added for connecting new capacitors.

Here's the alu brackets made for the brass bar holding the caps. The brackets are fastened to the corner screw of the transformers. The ones placed at the PSU transformer is slightly shorter than those mounted on OPTs.
New Miflex copper foil caps in place: Miflex KFPM-01 Copper Foil Polypropylene Film Capacitors, 0.68 uF/600V
Around 135 £/four.

Dimensions for brackets. The brass bars are 260 mm length.

Intermezzo

A friend brought his 2nd hand EAR-861 for a capacitor up-grade and all went well until I turned up the volume on some bass-heavy stuff and one channel started distorting seriously! Damn! We went through all solder spots and any possible thing we might have damaged and found nothing. Not knowing the true age of the amp or tubes I did some more testing and at low volume everything went well but when the amp had to deliver some amperes all went wrong. Hmm... These TESLA output tubes did look kind of old so I changed them with a spare set I have and now the amp could deliver the bass punch that is well beyond what one can expect from 32 watts.
My friend had two sets of spare PL519 tubes with the purchase and we changed the tubes and again - deep punchy bass. So, these PL509/519 can be too old. I never changed the tubes on my own 2nd hand -861 and these are the original PL519 with the TP logo. Considering its age, my -861 really cannot have been used much. Now, the bad thing about this experience is that my friend could not hear what the capacitor change does to his sound at home as the output tubes most likely does more than the change of capacitors. But he tells the sound is totally transformed - for the better. He has my DTQWT speakers and given their sensitivity was unlikely to notice the decline of the output tubes as they would never require more than a single watt or so.

 
My 861 rack made from oak boards. Click image to view large.

I don't think the EAR 861 gets much better. Mission accomplished!

BTW:

My oldest EAR-861 eventually needed new output tubes and I had a PL519 quad from an eBay supplier. What came as a surprise was that my EAR-861 was fitted with EL519, not PL519. EL519 runs on a 6.3 volt heater where PL519 runs on 40 volts.
Fortunately the EAR-861 is prepared for this as the mains transformer has both windings. Below you can see how.

Wires from the two PL/EL-519 circuit boards to the mains transformer.
Move the twisted wires from 6.3 volts to 40 volts.

Image from my new -861s. Runs 40 volts for heaters.