I'm cleaning out my HT for rebuilding, and think that you guys should see how we built amps in Denmark.
And after ill show some other amps i have kept, or collected for the look or reference of some kind.
First one is the inspiration to the Dali Lectron prototype, made in USA and the first real hifi amp i know of, made by John Iverson.
Electro Research A75
I have 2, one with very low hours and mint condition, and another one not so mint.
Its constructed with feedback in some very different way, and its adjusted with small bourns trimpots everywhere inside the amp, impossible to service, like no one know how to adjust it.
Its a very potent KL A/B 70W amp that sounds far better than most amps made today, with only very little high frequency distortion from the feedback.
Last edited by stridsvognen on Sat Mar 01, 2014 2:31 pm; edited 5 times in total
Link Posted: Fri Jun 01, 2012 2:15 pm Post subject:
Dali Lectron.
Here is the first danish build replacement for the Electro Research A75, its a 1 piece prototype.
Its with 0 feedback DC servo. Its rated 75W KL A/B and was meant to be 75W KLA, but it was impossible to keep the temperature down with that high bias. I belive its around 40W KL A. And active cooled with 1 120mm Papst ventilator.
Its around 70Kg
Last edited by stridsvognen on Sat Jun 02, 2012 9:13 am; edited 1 time in total
Link Posted: Fri Jun 01, 2012 4:01 pm Post subject:
Yes, I remember the Electroresearch very well. On of the very first amps that was designed to be able to handle the complex and low impedance of some of the early full range electrostats. Unfortunately it was out of my price range, so I had to do it myself.
Beautiful amps as is the replacement that I didn't know about!
Ill post some pics about other amps i have collected, maybe it gives some a idea whats going on inside my head..
Not all sounds good, but i most kept them as some sort of collection.
I have bought almost all my amps used, like this kind of equipment don't come cheep when new.
The Electro Research A75 in the pic i bought some years back on EBAY from LA, think i payed 2200$ with shipping.
the other one was from Singapore.
It all started with the big amp Dali Gravity. and i know the guy that build the prototype, so got some history to it, and got the possibility to buy the prototype later.
There is much more to it than the amp, but ill save the story about the pre amps and MC stepup to another time.
The Dali gravity is pure transistor build with DC servo and no opamps and capacitors in the signal,
Its completely DC stable from cold to hot, due to very hard thermal coupling of all transistors, so no DC drift at all.
opposite to what you see in other constructions with small cooling profiles here and there with single transistors.
Link Posted: Fri Jun 01, 2012 5:16 pm Post subject:
DENON POA 3000Z.
From around 1980 i bought it with a blown up output, and had it standing around for 2 years before i finally got it made, it took me quite some time to get it all cleaned up, and it took a few sets of output transistors before i found the problem.
Now its like new. complete new output transistors in both channels, and all new original nippon chemicon capacitors on all boards.
Cleaned in every corner, everything have been apart and cleaned.
I don't use it, but i'm drawn to those big VU meters, so sometimes i just turn it on to see it light up the display..
Last edited by stridsvognen on Sat Jun 02, 2012 9:14 am; edited 1 time in total
Link Posted: Fri Jun 01, 2012 6:19 pm Post subject:
NAD 3020 Series 20.
The one and only.
Everybody interested in hifi should have one of these. Not to look at, but to connect when everything else fails, this one will play music.
Its not the best bass or treble or mid range, but everything is equal bad, or good, a rare thing to find, nothing stands out as good or bad, you just listen music.
Worlds most sold integrated amp.
The one in the pic is a special anniversary edition.
Last edited by stridsvognen on Sat Jun 02, 2012 9:16 am; edited 1 time in total
Link Posted: Fri Jun 01, 2012 6:48 pm Post subject:
Noticed the Dafos album in your picture. IMO, Reference Recordings are the finest quality recordings ever done. If I can find the link, I'll share the best one they ever did.
Link Posted: Fri Jun 01, 2012 7:02 pm Post subject:
Boilermaker wrote:
Noticed the Dafos album in your picture. IMO, Reference Recordings are the finest quality recordings ever done. If I can find the link, I'll share the best one they ever did.
Bob
I have some RR recordings, its very hight quality, if i have to complain about something, ill say i prefer records less mastered to perfection.
They have some artificial over perfect sound. But Dafos can scare your friends to dead when it suddenly goes crazy dynamic..
It can actually beat up most equipment, and make it sound terrible.
Joined: 06 Mar 2006 Posts: 16775 Location: Ottawa, Canada
TV/Projector: JVC DLA-RS56
Link Posted: Sat Jun 02, 2012 1:53 pm Post subject:
I love it! More! more! more!
I have a thing for amps. Bigger the better, the heavier the better. Giant heat sink fins. I also prefer a 'classic' approach to amplification. Not necesssarily pure class A all the time but I'm not a big fan of the new digital switching amps.
Link Posted: Sat Jun 02, 2012 2:21 pm Post subject:
Awsome fred Kurt!
I will look forward to your new music/film room. Always a pleasure to visit the old one
We need more pics! I know that you have lots of other stuff
Link Posted: Sat Jun 02, 2012 6:41 pm Post subject:
Wow - That Gravity amp is truly a magnificent beast!
I saw on the back that it can be bridged which means it will probably supply 400 watts @ 8 ohms, 800 watts at 4 ohms, 1600 watts at 2 ohms, and I would not be surprised if it was stable into 1 ohm!!! Since you have two of them, do you run them this way or do you use an electronic crossover?
Since I couldn't see any way for the air from the two fans to be exhausted, do they run push- pull?
I'll bet it has at least 8 pair of output transistors per channel at a minimum. Are they bipolar or mosfets?
Sorry to ask so many questions, bu what is the AC output connector on the back used for?
Link Posted: Sun Jun 03, 2012 12:29 am Post subject:
Boilermaker wrote:
Wow - That Gravity amp is truly a magnificent beast!
I saw on the back that it can be bridged which means it will probably supply 400 watts @ 8 ohms, 800 watts at 4 ohms, 1600 watts at 2 ohms, and I would not be surprised if it was stable into 1 ohm!!! Since you have two of them, do you run them this way or do you use an electronic crossover?
Since I couldn't see any way for the air from the two fans to be exhausted, do they run push- pull?
I'll bet it has at least 8 pair of output transistors per channel at a minimum. Are they bipolar or mosfets?
Sorry to ask so many questions, bu what is the AC output connector on the back used for?
Thanks,
Bob
I just have one Gravity, but they are made for the megaline speakers with electronic crossover.
And its 2x100w 8 ohm 2x200 4 0hm 2x400w 2 ohm
It can be bridget like you mention, i never had any use for it, and i don't think its the way to use it right.
The air i guided down, and blown out under the heat sinks, and turned up from those plates you see under the heat sinks.
The ventilators are run one with 110v and the other 120v as i remember, and that way they run different rpm, and make less noise.
If i remember right it have 10 sets of bipolar Motorola TO3 output transistors pr side, and 2 sets of predrivers.
The AC output on the back is for the pre amp.
When i have some time ill take the top plate off and show you how it look inside.
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