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The ELD User-Selectable Hybrid Integrated Amplifiers
Well my friends, the circle of life does continue, and the great designer has once again come to our rescue. Gilbert didn’t get a lot of
warning that components critical to the DAR were about to be discontinued, so we all thought that it might take quite a while for him to
come up with a replacement. After all, he is insanely busy with production just trying to keep up with orders. Since he still builds
almost everything himself, where would he find the time to design and test a DAR replacement?  Luckily, we were wrong.
Unbeknownst to any of us, he had been secretly working on another one of his pet projects.

It’s been about 10 years now since class D amps first appeared in what can only loosely be described as high-end audio amplifiers.
Many of us, including Gilbert, were not very impressed with their performance. What we didn’t know was that he had been tinkering
away with output stages for some time, trying to see if he could design a class D amp that actually sounded like music instead of hi fi.
It would appear that the answer is a very resounding affirmative. A class D output stage is one of the two main features of the new ELD
hybrid integrated amps. Yes, there are two new ELD models. The smaller ELD is conservatively rated at 135 watts into 8 Ω and the
ELD-BD (Big Dog) is rated at a whopping 300 watts!
So, what do these amps sound like…or perhaps the question should be, what do the two versions of these amps sound like? In a way,
with both the ELD and the ELD-BD, you are getting two very good integrated amps here for the price of one. As most of you probably
know, we do not like to talk about the sound
of our own gear. Who is going to be more prejudiced than the actual designer is about his own creation? So, what we do at Blue Circle
is we leave this for others to describe, comment on, and criticize if appropriate. Gilbert really does listen, both to music and to the
opinion of others. He has a number of beta testers whose opinions he respects. The prototype of the smaller ELD was sent out to two
of these trusted reviewers and here is a bit of what they had to say:

The first beta-tester said that he thought that the ELD was overall a definite improvement on the DAR, but for most recordings he
preferred the solid-state sound to the hybrid. Interestingly, the second beta-tester said basically the same thing, except that he
preferred the 6SN7 hybrid sound to the purely solid-state sound. Both are very experienced and knowledgeable audio folks. Both either
have lived with the DAR for quite some time or actually had one there to compare the ELD to. To us, this goes to show just how
important it can be to give the user the option of choosing between two types of very good, but slightly different sound signatures.
Who doesn’t like options? Here are a few more comments from our beta-testers:

In solid-state mode:
“Overall, it produced a very natural musical experience with good ambience retrieval, clear and extended highs and bass that was
tuneful, deep with excellent definition.”
“…good ambience retrieval, clear and extended highs.”
“…voice comes across very naturally and more human vs hifi.”
And in hybrid mode:
“Voice was natural and accurate… so bloody good it’s scary.”
“Bass was deep, full and natural, not flabby at all.”
“It’s all there with tight detailed skin tone.”

Again, both reviewers felt that in either mode, this amp was an overall improvement on the DAR. One of them stated that compared to
the DAR the ELD had “greater clarity” and was “much more dynamic”. Both noted that the lower register was greatly improved. And
since this new amp replaces the DAR at the same price point and really offers you two amps for the price of one, we truly believe that
those who have lamented the passing of the DAR no longer have anything to mourn. The circle of life continues and life is very, very
ELD & ELD-BD Optional Features
Shallco 31 x 2 position attenuator
Black Plexiglas or custom wood faceplate
Stainless steel knobs
Custom color cover
Processor bypass loop
RF Remote volume control
Onboard DAC and/or Phonostage in a larger chassis.
Power on/off for tube stage when using processor loop to save tube life.

ELD & ELD-BD Technical Specs
Residual noise referenced to full power output, volume control at zero: >-105dB within audio band
Tracking error: < +/- 0.2 dB
Frequency response (10W into 8 ohms): 10Hz to 35kHz +0.00 dB, -0.2 dB; - 3.0 dB at >100kHz
Distortion at 10W into 8 ohms: < 0.3 %
Voltage gain: 38.5dB
Input sensitivity (reference to 10W) with volume control fully open: 0.1 V
Input impedance: 100kΩ

ELD and ELD-BD Standard Features
135 watts into 8 ohms and 270 watts into 4 ohms.(ELD)
300 watts into 8 ohms and 600 watts into 4 ohms (ELD-BD)
3 line level inputs
1 preamp output
Ground lift switch
Laser-trimmed Alps attenuator
User-selectable for 6SN7 hybrid or solid-state operation that
can be switched while music is playing
Stainless steel faceplate, wood knobs and black cover
Front panel - in standard stainless steel.
Ah, the ever revolving circle of life. First the late great BC2 single-ended class A mono-blocks passed away into history, but then the
DAR (Death And Resurrection) was born and many breathed a sigh of relief. The sound of the BC2 was back, but in a much smaller,
much cooler running, and less expensive platform. The world was right again. But then, horrors of horrors, we recently heard the news
that due to the discontinuation of some critical components, the DAR was about to go the way of all flesh… or in this case, all circuitry.
How were we to carry on?
The second and perhaps the most unique feature of these new ELD integrated amps is the “user-selectable” hybrid input stage. This
circuitry has its roots in research stemming from the BC307 cross-hybrid preamp and the BC107 SS preamp. We are calling these
ELDs “user-selectable” hybrids for the following reason: The front end of both ELDs contains a purely solid-state signal path and a
6SN7 based signal path, and you the user can switch between the two while the music is playing. This provides the listener with a
flexibility that few other components do.
(July 20,2015)
Despite what the late Harry Pearson proposed many years ago, the
simple truth is that in reproduced music there is no such thing as
an absolute reference sound signature. Reproduced recorded music
and live music are not, and cannot, be the same thing; they are
very different art forms. Recorded music is not just about the
performance of the musician(s), it is also very much about the
“vision” of the producer and the sound engineer. Then there is the
interaction between the various audio components in the signal path,
how much noise is on your AC at any given time, not to mention the
room acoustics. For that matter, your mood can influence how you
react to a given recording on a given day. The user-selectable ELD
gives you some options on how to address some of these variables.
For example, in any music collection there are some recordings that
are a little too laid back and others that are a little too aggressive.
All things being equal, a solid-state amp may be the best choice for
the former and a tube amp might help round off the edges of the
latter. But of course, listening to music is much more complex than
that. We all have different tastes and those preferences can change
depending on so many factors. What the ELD allows you to do is to
instantaneously, while listening to a recording, switch between the two
signal paths. You get to choose which one sounds best  for any given recording in any given system at any given time.

17.5" wide x 3.5" high x 15.5" deep
add 1.25" for the binding posts on the rear
add 1.25" for the control knobs on the front

Weight:  28 LBS for ELD and 30 LBS for ELD-BD.
Contact:  bcircle@bluecircle.com  /  519-469-3215
Rear panel