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ONIX OA21 reborn...

Hi Echann

I studied Production Engineering, mainly in the Cockcroft and Mithras buildings on the Lewes Road. Remember the Escape, Richmond, Hungry Years. Loved it in Brighton, great nightlife and revising (drinking) on the beach. Good times indeed.
 
I registrerad here just now solely in order to post an appreciative comment towards Adam W!
It is so rare to find this level of quality for one thing but especially this level of service mindedness!! I salute you honorable knights of customer relations!!

Well, I too have on old O21 that I bought off a friend who went the Linn path from then on. Eventually however the volume potentiometer started giving up and I was loosing sound in one and sometimes both channels. I still have it boxed up somewhere awaiting restoration. I would love to have it handled with due care by its original masters, but alas, I live in Sweden and I suspect shipping would be an obstacle...

With utmost respect,
Anders
 
Hi Adam,
I had one of these for repair in my workshop a while ago. Some of the electrolytics had dried out and burst, otherwise it was in fairly good knick.
Yes, electrolytics can last 30 years but these ones were the victims of the power supply ripple.
Great renovation job!
David
 
Onixdna said:
Hi Mike

First let me apologize for the delay , I hope you will understand why it took so long , the task of renovation was down to me , and the last year has been crazy busy , credit to Sean for chasing me most weeks .. he was relentless . My schedule overseas has meant that time just went between each process .. Once again sorry for the delay .

For further info of your unit , it was made in Sydney Street Brighton in the UK on 25-05-86 , over 30 years ago. The PCB board was assembled by Myself or Tony Brady as at that time only two of us were working there building boards .The unit may have been finished by Tony, Craig or Myself .The twisted wires on the back of the disc input are called a "Humbucker" and were twisted to reduce hum , slight hum was picked up in early units with MC disc boards. We all hated making the Humbucker .

The disc board is unique as the discrete devices that we used then, are no longer made , treasure the disc board as it cannot be replaced, these great sounding low noise transistors are a thing of the past ..Sadly.

When I listened to your amp the memory of making the OA21e in the early days came flooding back, the layout of the work area, and the people I was working with, and then each unit being listened to in Craig's shop" Brighton HIFI" before shipping. The case work was carried out by a company called precision metal products in Shoreham by Sea Sussex, the PCBS were made in Newhaven , the case work was Powder-coated in Seaford and most components sourced from STC or RS.The shipping boxes were made by Cambridge Corrugated and our company was driven by enthusiasm and youth, we were all in our early twenties.

When your unit came to us at ONIX GB nostalgia drove me personally to bring it back , if only as you say "it deserved it" , I am glad you appreciate it.

Guys, lets keep great sounding music alive , I know at least one more unit is doing exactly that , I enjoy music every day and I enjoy what we do to make it better .


Adam W
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Onixdna said:
The OA21 is an old design .. This means it takes a long time to dismantle and work on .. It is also very well made, so there are lots of processes to carry out in a renovation .

We selected the best components we could get in those days ..The proof is in how many still work .. We do exactly the same now with all of our new stuff , but a huge misconception is that Capacitors dry out over time. They do not by default dry out, if they don't get too hot and are sealed the way they should be and are not stressed too much and were made by a good company , they will work for 30 years or more . Add to this the integrity of the manufacture making the capacitors, and the design integrity of the product they are used in , and life expectancy is ultimately defined . This means not all OA21s require renovation . Switches do get dirty and they do need changing or cleaning but again these are environment dependent and do not fail just because of age

In all electronics there is a very simple equation, quality is not a right, it is earned .. By time and reputation ..Spec means absolutely nothing, it is and always has been just a guide line. Design is not just a theory, it is an art, that is once again earned by experience and knowledge of how you want the components you use to work within their intended environment , and for how long . Electronics is the king of manipulation regarding specification ... Remind me PMPO and RMS, how many ohms what type of input into what load Etc Etc Ect ... Come on, its just all bullshit, and components are no different. What they really are is the only spec that counts, and that is not a sheet of paper with the manufacturers print within.

We design using an age old principle of 100% head room on spec .. If we want it to work at 30 Volts we spec 60 Volts, if it must have a gain of 20 we spec a device than can create 40 ...Etc Etc

its called good old engineering not, spec driven hype.

We will renovate the OA21 and OA22 but due to our ability to order old components and how long they take to get, E mail us and we will note your interest and stay in touch, It seems I am one of a few that can do it these days ( being involved in its design ) so my time is also a consideration .

The OA21s was a truly unique Amp ..it was cheap to buy, extremely well made, and worked beyond all expectation , it deserves to live on, and we will help it to do so, but please understand any electronic product that's 30 years old or more, is an old product, and it really falls in to a classic status . Time is required to do the job well , patience is a virtue to its successful survival.

We can do it, and we will do it , but please understand its not that easy to replicate the quality we built in in those days ..we know too well with our new stuff how hard it is and the parts required to make it all happen are far too often not that easy to obtain.

Far to many buyers buy the spec sheet, and far to many buyers just buy on price .

Drop us a mail

Adam W
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Hello Adam

I'm sure you may have put a few oa21 together but I feel, My Self Paul, Diane, may have put a few more together in them days, As I remember in the early days you used to work only part time when we was busy to help out, Later after you bought Craig out there was me Phil and H did most of the building wiring and testing. I still have one of the old yellow component boxes that were use to build the oa21 with a few original components still in there. I even bought myself an oa21 a few years ago and replaced the relays now working great again, One that I originally built with my test markings on the caps.

Glad to see there is a following for the old Onix amps built to last

Regards
Paul Haworth
 
May I ask what are the values of caps that you have used in the PSU ?

I have seen people putting anything from 4700 to 6800uF, 50V to 63V.

I have just bought an used OA21S and would like to replace those.

I have noticed, that one could probably even fit 12.000uf / 50V low ESR (28 mOhm) caps in 30x50mm package (UCC premium SMH series):

https://eu.mouser.com/ProductDetail/United-Chemi-Con/ESMH500VSN123MR50T?qs=sGAEpiMZZMtZ1n0r9vR22dBjIkbB%2b54Pr1RyAY1iboI=

Would those work ? Would I need to replace the recti bridge as well for higher amperage ?

OA21S was clearly designed to a price point, but if you can upgrade it for just a few EUR more ... then why not.
 
The amp runs on 36v from memory, so 50V will be fine, no need to go to 63V, unless there are decent caps that will fit. 25mm dia was always the limiting factor when I was mucking about with my OA21.
 
Simply increasing the capacitance of the reservoir capacitors is not necessarily an upgrade. With 4,700 uF capacitors fitted you already have 9,400 uF on each power rail, If you go up to 12,000 uF types you will have 24,000 uF on each rail which could give you surge problems on switch on.

The power rails are +/- 36V so 50V working capacitors are more than sufficient. I used 4,700 uF 63V Kemet ELH capacitors (40 x 25 mm) in one of my OA21S amplifiers and am very pleased with the results.
 
We have put those UCC SMH series 12.000uf / 50V low ESR (28 mOhm) caps in 30x50mm package. The amp works just fine with them. We had however to drill some small holes in the PCB to make all of them them fit - thankfully, the traces on the PCB were wide enough to accomodate new soldering points.

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I put the old blue BHC ALC10A cap next to them just for reference.

The exact BHC model is discontinued, but a modern BHC ALC10A variant in 25x40mm package is now 3900uF and has ESR of 99mOhm - 3x higher than the SMH caps we had chosen.

We have measured the old PSU caps and they all measured only half of their rated capacitance (2100-2400uF), so I urge everyone who hasn't replaced them yet to do so.

The output transistors and that small aluminum slab acting as radiator can get really hot (especially when when driving speakers that drop below 3 ohms, as my Magico M3 do) which shortens the life expectancy odf the adjacent PSU caps significantly.

If anyone wants to go with the stock (or close to stock) capacitance values, I would go with the 105'C rated caps in 25x50mm package.

I have also set the bias anew to 18mV - it read 4mV only.
 
Would love to get my hands on one of these, but they are as scarce as hen's teeth in the U.S.
 
Ragaman said:
Finally....FINALLY!!!!

My entire ideology of hifi equipment in a single post.
Nice one OnIx.

That 3rd paragraph put a large smile on my face as it is & always will be, the way to design the best hifi.

What a great service BTW
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Agreed.
The only piece of Onix equipment I have is a linear PSU that came with my Oracle Delphi TT. It works fine, BTW.
 
Neewbie here. I've just acquired an OA21S in the past week and am delighted by the sound. However, it seems to pop and cut out when the music volume gets too high. Any ideas? I wonder if my cd output is too great for the input, or am I talking nonsense? I am such a fan of this amp though!
 
JonathanB said:
Neewbie here. I've just acquired an OA21S in the past week and am delighted by the sound. However, it seems to pop and cut out when the music volume gets too high. Any ideas? I wonder if my cd output is too great for the input, or am I talking nonsense? I am such a fan of this amp though!
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Sth is not right with the amp. A dried up caps maybe ? I would start with replacing them anyway.

My OA21S was driving the Magico M3 speakers without any problems, although it DID get very warm after 30 min or so, so I do not recommend a difficoult to drive speakers for this amp. But it never cut out.

BTW - what speakers do you have ?
 
I've just had our OA20 serviced by JJ at Witch Hat , we use it in the kitchen with a baby Teac CD player and a pair of AE Acoustics compact speakers .
Mrs rosie reports that it sounds fantastic , it's been keeping her company during the Christmas Baking , I am so blessed !
The boys at Witch Hat charged me for a Nait service which is very fair especialy since they had to order some parts . I wouldn't swap it for a Nait I, Nait II or 3 ,and I 've owned a 3 , borowed a CB Nait II and have listened to a Nait I at my dealer all those years ago .

Like others on this thread I too had fun in Brighton in the 80's with an Art School crowd , the town seams to have lost some of it's vib in recent years .
 
Is Onix in UK (the real Onix) still refurbing the OA21's? (I saw this thread started about a year ago). I emailed them from their site and called and left a message but no one got back to me. I have an OA21 that could use refreshing... seems like wandering grounding.
 
tapashead said:
Is Onix in UK (the real Onix) still refurbing the OA21's? (I saw this thread started about a year ago). I emailed them from their site and called and left a message but no one got back to me. I have an OA21 that could use refreshing... seems like wandering grounding.
Click to expand...

I contacted them last May and they agreed to service an OA21S for me. I spoke to Adam W who told me that he does them in batches and that they hoped to be able to ask me to send it in July (2018). I chased once by e-mail last Autumn but with no response.
 
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