EK-1, Info

Read more on the Electro Research EK-1 in our home audio section

John Nunes2006-04-03 08:28

This is correction of the description of this unit. The chassis is not from machined aluminum, but is cast stainless steel. Yes, you read that right. John Nunes San Jose CA


Brian D. Smith2006-05-24 04:29

John, Thank you-I stand corrected. Like I said, it has been a few years, but you have jogged my memory. The weight should have reminded me(too heavy to be aluminum), and I remember casting marks inside the power transformer compartment. I have an interesting bio on John Iverson I could email you, if you want. It is about 20-30 pages, and goes into considerable detail about the circumstances surrounding his strange disappearance. Thanx again! -Brian D Smith Hollywood, CA

John Nunes2006-05-24 05:59

\"I have an interesting bio on John Iverson I could email you, if you want. It is about 20-30 pages, and goes into considerable detail about the circumstances surrounding his strange disappearance.\" Hi, If it is the article that was in The Absolute Sound, I\'ve already seen that. But if you have something different, then yes, please send it. Do you know anything about the circuitry in the unit? It\'s all potted, so you would have to destroy one to find out. I\'ve never found anybody who knows a thing. I\'ve even emailed one of the Tan family (who were the investors in ER, and they don\'t reply. John Nunes San Jose CA

Brian D. Smith2007-02-11 14:13

John, Yes the article I have is from The Absolute Sound. Great story, though, hmm? As far as the circuitry of the EK-1, well. perhaps the following will be of SOME help to you:

The unit that I worked on was purchased by a friend of mine in "as-is" condition at a garage sale in or near Van Nuys, CA for(get this)$15.00 from someone who didn't know where it came from or what it was.

It powered up, but passed no signal and showed something like 18 Vdc at the output jacks. After taking it apart, some voltage testing at labeled PC board points indicated a failure in the potted power supply regulator module, and a couple of bad electrolytic filter caps. After de-soldering the module from the board, I deduced that the thing had 3 sets of supply rails: +/-12v, +/-27v, +/-39v, and that these were "stacked" on each other, I.E.they shared filter caps(hooked in series). 12+27=39!

I actually ended up grinding the potting out of the module(around the outsides first, to try and examine the circuit). This proved to be not very helpful as the epoxy was very tough and tinted opaque dark gray, but I did crack it open in a few spots. The design appeared to be 3 sets of all-descrete, zener diode+(TO-220)transistor regulator circuits. Nothing too exotic, no exotic parts(but no crummy parts, either). I reconstructed the circuit using monolithic 3-pin regulator IC's, mounted to the case(w/SHORT screws!)for heat dissipation, arranged the I/O leads w/ extra sticking out, mixed up some fiberglas resin, tinted it, and poured 'er full!

It worked fine, and it got rather warm(the module casing),indicating a fairly decent current draw. This suggests class a circuits throughout. No big surprise, really. Most preamps are class A, as the high output impedance means a small current flow at the output. Also, this cured the DC offset at the output jacks, strongly suggesting direct coupled gain stages, at least in the output driver circuits.

Overall, the unit contained 12 modules, I think. Maybe 10; I'm not certain. There was only 1 regulator module, and 1 rectifier module; all the others were mono audio signal, in pairs. The ones that I found of particular interest were the L & R channel "Phase correction" modules, which had(I think) 3 sets of test points marked something like H,M,L(Hi,Mid,Low?)I did some bench testing w/a scope & spectrum analyzer and concluded that these were similar to Barcus-Berry's "BBE" processing. The pro audio models, such as the 802 have 3 parallel processors; high, mid, low, and basically put pre-emphasis, frequency dependent phase compensation(advance the phase angle of HF signals) to compensate for HF phase lag created further down the signal chain. Is this cheating? Is it the solution to a legitimate problem? Not my place to say. All I know is that the damned thing sounded FANTASTIC, and, isn't that what its all about?

Hope some of this was helpful, John. I would be quite interested in any other goodies you have on Mr. Iverson. Sincerely, Brian D. Smith

John Nunes2007-02-14 05:24

Thanks for the info in the power supply regulators. The phase compensator modules have 3 pots for each channel, each adjusting low, medium and high frequencies, with lots of overlap and modulation between them. They are for fine tuning the frequency response of the strain gauge cartridge. Using a sweep record and several iterations with Cool Edit, you can get the response to be flatter than any other cartridge I\'ve ever measured. (or any almost any particular curve you might want to impose) This is a really great thing, since cartridges are not particularly flat in general. Is it flat in absolute terms? It\'s hard to say what that is, since it depends on what test record you use. As to what\'s actually in the compensation modules, your analysis is interesting, but obviously it was done in the analog domain rather than in digital as in the Barcus-Berry BBE devices. I\'m told that at the factory, they used a recording of a square wave from the CBS STR 110 test record, adjusting the pots until the square wave looked the best.

Iz_isaac2010-08-30 02:53

hi... does anyone could gimme a copy of operating instruction of this pre..
thanks in advance..

Jim Kolessar2011-02-11 07:10

To John and Brian,I have read your posts about the Iverson EK-1,and they were very interesting.I had also read the story about Iverson,and that in itself is also very interesting.Now getting back to the EK-1 unit itself,I have just purchased one with the 451c sttrain Gauge,and am very skeptical about putting power to it without replacing the caps,as this thing has been out of operation for about 4 years.

Do either of you have any op manuals or schematics you could copy and I could purchase from you,or know of anyone who may.Any help other than what you have already posted would be greatly appreciated.

Jim Kolessar,Sun City West Az.
Email soundsofmusic2@gmail.com

Brian D. Smith2011-02-21 07:59

The EK-1 main power supply capacitors are quite high quality. I would not be surprised if yours powers up without a problem, and, even if one is going(or gone), the supply components and layout are quite robust. At the worst you would have some substantial hum at the outputs, but I highly doubt that any other parts would be damaged. The caps can be accessed by removing the bottom cover screws, then turning the unit right-side up to remove the cover(the fit is so good you cannot even fit a razor blade between the edge and the chassis!). There are 8 caps, all in matched pairs and of the axial lead type. I would recommend clipping the leads off with about 1/4 inch sticking up from the board, then soldering the new ones to the clipped leads. Removing the board becomes quite a sticky wicket at the back end, as the RCA jacks pass through both the upper and lower boards, which are separated by the 1/2 inch thick solid center of the stainless steel chassis and thoroughly soldered in on both sides of both boards(the heat required to unsolder them will destroy the insulators in the custom RCA jacks, leaving you with the task of finding replacements, let alone putting them in without damaging them--Yes, ashamedly, I speak from experience!)
Sorry, I don't have any schematics, nor have I ever seen one. Making one is pretty much impossible due to the potted modular construction, so if Electron Kinetics doesn't have one, I think you're out of luck. Fortunately, other than the caps, the thing is pretty bulletproof and should last for 100 years. Good luck! Enjoy your treasure- I hope this has been a little bit of help. Cheers! -Brian D. Smith

Jim Kolessar2011-02-21 17:37

Thanks Brian,I really appreciate the feedback.I have been asking questions about the EK-1 all over the net,and have received very little feedback if any.Your reply offers the best info that I have received to date.Tho I did get a response from a gentleman who supposedly worked with Iverson in Calif.and he said he did have some info,but that it was in another country in storage away from him,so he will not have access to it until May.Thank you again for your reply it is much appreciated.

Jim Kolessar2011-02-21 17:48

A few more things if you don't mind.I am sure you are talking about the large blue caps.But how about the smaller yellow IP22 caps with the black band at one end? And also does the P in the ident stand for positive ended?My Tech said he had never seen a cap with a black band on the end.
Thanks again Jim

Azirul2011-04-17 01:47

hi all... especially Brian and John,
my EK-1 gave a problem this morning.. 'it produce high frequency noise on Left Channel (no music at all)...while Right Channel is ok.
immediately opening the top and bottom cover, I found out 1 of 2 of "black box" indicated HIGH LEVEL AMPLIFIER, the temperature was hotter compared to another. is it gone bad?? or just any bad capacitor
that I should check for??



Johnyuen2012-01-21 22:26

Brian & John

I have been following this thread for quite sometime now.
I do own both the EK 1 & A75
They are Tanks. Have u seen the solder they use on the A75 circuit boards. Unreal how much they used.
Quite lucky to be living in Singapore where the EK1 was made so I managed to pick up 2 more EK1's
and managed to get 2 of them working & one as a parts machine.

Unfortunately both while sounding good, hisses quite loudly even with the volume turned completely down. Any idea if its inherent or is there something I need to check. One of them is completely re-capped but still.......

Pulling my hair so any suggestions welcomed.


Azirul2012-01-22 05:56

hi Johnyuen....

do you mind contact me thru my email.. iz_isaac@yahoo.com


Dan Siefert2012-12-04 06:01

Hi all,
I just joined this discussion. I know it has been going on for quite a while and perhaps everyone has moved on. . .
I worked with John Iverson during development of the EK-1. I relocated to Singapore to help get the EK-1 into production. I am telling you all this to establish that I know quite a lot about EK-1s, A-75s and John Iverson. There is a lot of mis-information here and all over the "net". If anyone is still watching this thread, let me know and I will be happy to answer any questions. Also, I am available for Electro Research restoration/ repair projects. Lastly, I recently listed my personal EK-1, with calibrated cartridge on eBay. If you are interested, go to eBay and enter 150955792245 in the search field for the full story. My contact information is there.

Henri Monat2017-09-29 13:21

I've just receive an EK1.
Do you have any manual with data and circuit?
Best regards.

Henri Monat
from France

Stan.2017-11-15 19:45

please can any one help i need a circuit diagram for my e-k1 pre-amp there is no plu voltage from the regulator module. also one of the line amp packup. thanks.

Erico2018-11-07 16:21


Je possède deux pré amplificateur EK1,depuis plusieurs années.

Quel plaisir d’ecouter

J’ai deux questions à vous poser.

J’ai un des pre amplificateur qui vient de tomber en panne,plus de son.

Qui peut réparer?

Et le deuxième pré amplificateur a un canal qui donne plus que l’autre.

Comment réparer ?
Cordialement Eric

I possess two meadow amplifier EK1, for several years.

Which pleasure to listen to

I have two questions to ask you.

I have one of meadow amplifier which has just broken down, more sound.

Who can repair?

And the second meadow amplifier has a channel(canal) which gives more that the other one.

How to repair?

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