EDISON 60 Amplifier Kit - Initial Impressions
Thor...@tnt-audio.com
I just took delivery of my Edison 60 Amp-Kit. As there have been a few
Questions about this recently in the Tubes NG, I thought I let you have my
first Impressions....
Fairly detailed Info on the Kit can be found on the web here:
http://www.hi-fidelity.co.uk/edison/
My impression of the Quality of the Major Parts is quite favourable. Most
importantly, the Output Transformers are serious hunks of Iron. Indeed, as
our Girls at reception had to receive the Packet I ended up promising to buy
them lunch because they where seriously annoyed about the weight of the
parcel ;-)....
As the Edison can be connected either as Parallel Single Ended Amp or
Push-Pull Amp the Output Transformers have an Airgap. The Core-Size looks
right for about 30W in SE.
The Output Transformer has Output Tap's for 2, 4 and 8 Ohm and the Primary is
made up from four identical Windings, which allows for a wide range
of Connection Options.
I have seen similar Output Transformers priced at 150 US Dollar each, so the
Output Transformers account probaly for almost half the cost of the Kit.
As Self-Biased Push-Pull Ultralinear connected Amplifier an Output of 30Watt
is claimed, for PSE Ultralinear 18/20W....
An Option is available to use a fixed bias Class AB Circuit delivering about
50 Watt Ultra-Linear, however I do not think this a very advisable option,
still if you need the Watt's....
The Mains-Transformer in the Standard Kit is a little on the small side,
however still sufficent. It is a 100mm Diameter toroidal Affair, larger
than what most japanese 2 X 100VA Mid-fi Amplifiers sport.
A second Transformer can be purchased for about $110 and fitted with obvious
benefits.
The "Star" of the Show is actually the Casework. Anyone who has seen the
Maplin 4-20 Kit (it has just the right looks for the "Honey look what
followed me home" Crowd) will know what one does not want sitting in ones
Equipment Rack....
The Chassis is actually of exactly the same style as used by Alema (the
Company behind Edison) in the reknowned "Audion" Range of SE Amplifiers. Even
without the optional polished stainless steel front/top Plate and without the
optional wooden side-cheeks the Amp will look rather nice.
In line with many other Audion-Amplifiers the Edison is actually an
"integrated Amp" with three Inputs and a Volume Control....
An Alps Blue Volume Control is offered as optional Extra (~$ 16) over the part
provided as standard and I for one would recommend this Upgrade highly....
The Socketry provided as standard is pretty basic, better RCA Jacks and
Binding Posts can be purchased from Edison/Alema or at your nearest
Electronic Store....
For the record, I received the optional Sockets and Binding-Posts, and the
Binding Posts are a lot better than what I normally fit, the RCA Jacks of the
usual "Tiffany Style" Design with PTFE Insulation.
The Quality of the remaining Parts (Capacitors, Resistors and so on) is what I
usually call "Industrial", meaning no fancy Boutique Cap's or Black Gate
Electrolytics, but then what do you expect for a Kit price of about 650 US
Dollar?
The supplied Valves are four Sovtek EL34G and four Sovtek 6922 Input/Driver
Valves.
Considering the Price as 30 Watt Class Push-Pull Kit, the $ 650 may seem not
such huge bargain, until one considers the Range of possible Options....
The basic Kit can be a 30 Watt Ultra-Linear Push-Pull or 20 Watt Ultralinear
Single Ended Amp (competition for the GTA SE-40 brewing here maybe?). Triode
Connection is of course possible and the Amp features the (IMHO) completely
indispensable output tapping to accommodate a wide range of Speakers....
It is quite possible to start with the basic Kit and at a later stage (when
funds allow) to upgrade the Unit to Dual Mono Powersupplies for example.
Lastly, If I'm not mistaken, the two 3.7V 4A Heater-Windings per Mains-
Transformer (not used in the Kit) make a nice rectified and filtered 5V for a
300B Filament and the Output Transformer certainly looks beefy enough to make
(a slightly marginal) but competent OPT for a 300B PSE Amp....
How'z dat?
With all options fitted (both the "Visual Helps" that make the Amplifier look
"pretty" and all the electronic Improvements) I'd dare say, that I cannot wait
to put the Amp together and have it playing....
A full review will be available eventually in the Pages of TNT-Audio where I
will cover all the various connection Options and their sonical impact as well
as the sonical results from fitting the various Upgrade Kits....
In the meantime I'll be posting a few impressions while I go along in the
rec.audio.tubes NG....
Kind regards Thorsten.
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Gustaf Tham
I got no reply when I asked few weeks ago about the Edison
amp kit. Since then I've built one, it's playing right now, and the
sound is beautiful! Now that I see Thorsten is going to write his
impressions of it I feel I'd better beat him to it, before I'm biased by
his much more experienced analysis.
I'm not at all in the high-end hi-fi league, just an attentive
listener. Also I haven't had a chance to listen to good tube amp for
years. So please take this for what it is...
I went to Stockholm to meet the designer of the amp, Erik andersson.
He turned out to be a nice guy, no hype, shelves filled with his earlier
tube amps. Probably has KT-66s for breakfast.
I brought my own CDs, listened on Erik's Audio Note speakers, the
amp in ultralinear P-P configuration, with individual power supplies
(an option). The sound was spacious, well defined. Without hesitation
I bought a kit. Had a nice talk.
Assembly was fairly simple (see below), took more time than I had
expected, though.
I first wired it in parallel single ended triode mode.
My speakers are home made, bass reflex, 55 litres, 87 dB, designed
specifically for a LTS, a Swedish audiophil society.
To the point - how did it sound? There are some very obvious
differences to my old class AB transistor amp:
- Much better stereo image, particularly depth. With some CD's
the orchestra is quite obviously sitting in my front yard, and you
could give a good estimate of the distance to the harpist.
- Extremely clean sound. When playing complex, music (like
Palestrina choir)on my former amp there used to be an irritating
noise and lack of clarity. IM-distorsion, perhaps.
This problem is totally gone now.
- Many instruments simply sound more beautiful, most obvious with
strings perhaps. A slight, song-like quality is added,
tubeishness I suppose.
At first I thought the amp was a bit thin in the bottom, but I then
borrowed a Quad 405 and discovered that my old amp had way too much bass.
I only had the Quad a short while, but am fairly confident the Edison
sounds cleaner, particularly at low levels, and gives a better defined
3D image.
Since my speakers are a bit dominant in the mid-to high freq, I rewired
the amp in P-P ultralinear mode. This rendered me a bit more bass,
subjectively slightly more than the Quad.
At the same time I think I lost some quality in the higher registers
(it says in the assembly note that I might...) and a wee bit of that
special feeling of "thereness", but not as much as I expected, changing
from SE to PP.
I also listened with earphones (AKG K500), the amp loaded with resistors,
comparing to a Creek OBH11. I prefer the vibrance and presence of the
Edison.
A few words about the kit:
Generally nice. I don't like the combination of tubes and PCB's
but that's probably the only way to go if you want to keep the price
down. Also it simplifies assembly.
Resistors are metal film, PCBs are good quality, nicely solder masked.
Connectors are simple but working. The output transformers are very
impressive. There are no chokes, but RC-networks. Appropriate bleeders
are used, anode voltage being over 450V.
The mains transformer is a toroid one. This is the only thing I don't
like: It gets hot, according to Erik it will reach 80 degrees C
after many hours. The transformer is specced at 150 degrees, so
it will be all right, I just don't like that much heat in the vicinity
of electrolytes in the relatively ill ventilated rear of the chassis.
Anyway, if you are as finical about this as I am, there is a simple
solution:
Buy two power transformers and two power supply PCBs; this is an option.
That way you will in effect have two monoblocks.
As an alternative, you can reduce power consumption by wiring the amp
single-ended, using just one output tube in each channel.
I tried that, and there was plenty of power for me.
The chassis has a nice finish. The stainless steel top is an option -
do get it! It looks absolutely great, and a nice looking equipment
has a tendency to sound better. Psychology, that.
I've been soldering, wire-wrapping and tweaking for 30 years,
but never assembled a kit before. Don't fall into the trap I fell into:
I was too much in a hurry, and completely forgot to solder not one, but
two terminal pins, resulting in intermittent strange behaviour. Since you
can't see the solder side of the PCB's once they're mounted in the
chassis, it took me quite some time to find my mistakes.
A final word: Listening on the Edison to a good recording of a symphony
orchestra playing at low levels can be almost spooky; the air vibrant and
you can really experience that you are in a BIG concert hall...
Check back and see what Thorsten and others write about this amp!
Cheers
Gustaf Tham
Sweden
In article <6qc3p1$717$1...@nnrp1.dejanews.com>, Thor...@tnt-audio.com
says...
> Hi all you cool Dudettes and Dudes,
>
> I just took delivery of my Edison 60 Amp-Kit. As there have been a few
> Questions about this recently in the Tubes NG, I thought I let you have my
> first Impressions....
>
SNIP, SNIP - impossible to post with so much quoted...
> Fairly detailed Info on the Kit can be found on the web here:
>
> http://www.hi-fidelity.co.uk/edison/
Thor...@tnt-audio.com
Peace!
Last Time around I gave everyone a rundown of the Kit's content.
Over the weekend I managed to build up the Kit and have been listening to it
since Monday....
Building the Edison 60:
----------------------------
Well, the Instructions are clear and concise. Everything went together fairly
simple and fairly uneventful.
It took me a lot longer than it should take normally, as I received any Option
possible under the Sun and decided to fit them all.
However, in order to get a handle on how the UK Pound 400 Basic Kit sounds I
had to make sure that I had all options fitted BUT NOT ENABLED....
This required a large quantity of additional PCB-Pins to be fitted. As result
I am able to very quickly switch between the Various configurations. This was
done because it is fairly difficult to remove the PCB's and work on the
Solder- Side once fitted.
As a result of this it is also vital TO VERY CAREFULLY CHECK YOU WORK prior to
fitting the PCB's in the Chassis. Correcting Mistakes later will take much
time....
Fitting two Mains Transformers proved a little challenging at first. After
discussing this with Dave Chessell from Alema/Audio, Dave noted that future
batches of chassis would come suitably pre-drilled drilled to accommodate
either one or two Mains Transformers, so you should not have the problems....
As noted I was also supplied with the (optional) better RCA Jacks and
Binding- posts. Considering the substantial difficulty of re-fitting these
later I build the Kit with the better connection Hardware.
I also added a "direct" Input bypassing the passive linestage, as my System is
primarily Vinyl oriented and hence has got a superb Preamp.
The Volume Control in the Kit is made by Alps and the same (sans Motor) as
found for example in the well-respected Marantz PM-66 KI Signature Amplifier
(UK Pound 400). It is however not the last word in transparency. The Channel-
tracking on these Controls is very good BTW if my own experiences are anything
to go by.
I also decided to use my favourite wire for wiring the Amp. Again once fitted
the Wire is hard to upgrade or replace. I think such small changes are within
the scope of what any individual Constructor may do.
Indeed, I cannot really cite Alema/Edison for packing fairly nondescript wire
with the Kit. Such a wide variety of opinions and preferences exist that
certainly whatever would be packed with the Kit would be the wrong stuff for
someone....
Only one more note on connectors and wires. The Loudspeaker Connectors
supplied in the Basic Kit are perfectly serviceable, but in true british
Tradition Banana-plug ONLY. You cannot use Speakercables with Spades
directly.
At only UK-Pound 2.50 each, about USD 4.00 (as per the Pricelist on the
Edison Web-Site) the optional Binding Posts will accept any form of
connection up to the most monstrous Spades. They give little in Design, Sound
and quality to the WBT ones that cost real Money.... They are highly
recommended for anyone in need of something other than Banana Connectors.
For the whole Amp, it is probably a good Idea to lay out the major Parts in
front of you on the empty workbench. Then read the assembly manual (again) and
think through in which sequence it would be best to assemble what.
The Manual is quite good on that, however it is still only in "Beta" as it has
been only recently translated from Swedish into English.
I feel for example that it is advantageous to first wire up all the RCA-Jacks
in the Bottom Chassis Assembly and to then wire the Loudspeaker Connectors
before finally fitting and wiring the Output Transformers.
Both RCA-Jacks and Speaker-connectors are otherwise hidden behind the Output
Transformers and hence fairly difficult to get at. This is not specifically
mentioned in the manual.
So applying a little forethought (just as with any large project) will speed
up things no end and also make the assembly a much more enjoyable experience.
I am sure subsequent revisions of the Manual will address such minor issues.
The assembly of the PCB's is straightforward and simple. As I had only the
downloaded Manual published on the web, I do not know if the final printed
Items includes Photographs of the finished Boards or (better) an enlarged
Stuffing guide. I personally at least find such things useful.
Lastly, PLEASE MAKE SURE TO TAKE THE SAFETY NOTES SERIOUS. Also make sure
electrolytic Capacitors go in the right way.
If you are not particularly experienced in electronics it might be a good Idea
to have the boards checked by an experienced Friend before fitting them.
If you do it all by yourself, leave the assembled boards for a night and look
at them fresh the next Day.
In the end, after two Day's work (well not all day long - it's Summer so I go
out as well ;-) ) I was ready to Power the Unit up. Do not do this without a
Load Attached to the Output. Tandy/Radioshack sells very nice 20W 8 Ohm
Resistors, which is what I use for such purposes.
Also do NOT switch the Amp on without the Valves Fitted.
All valves lit up. All Voltages measured Okay (a bit high, but that is the
252V AC delivered to my Flat). So, I connected a CD-Player and Headphone up -
and got (almost) no Sound!
What had happened was that I had wired the front-end for Push-Pull operation
and the Output Transformer for SE Operation. Hence the Signals cancelled out
in the Output Transformer and thus- no sound.... Given how little leakage
was there the AC Symmetry of the Edison Amp seems impressive.
I was less impressed with the amount of Hum produced by the SE wired Output
Stage (Headphones do exaggerate this somewhat), so I rewired the Output as
Push- Pull. The Hum went away totally, proving that it is just a PSU issue in
SE Mode.
A (optional) Set of Capacitors for the Audio-PCB is available and works as far
as reducing the hum is concerned.
This is not part of the basic Kit however, so the SE Mode of Amp may give you
some Problems with Hum without the additional components fitted. Much will
depend on your specific Speakers.
After correcting the wiring and closing the chassis I took the Amp into the
Living Room and connected it to the System....
More about the early listening Impressions in another Post later today or
tomorrow....