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Unfairly forgotten classics

I'm obviously biassed in favour of the old Armstrong 600 range, so my views can be discounted a bit on that basis. But I have always liked the look of the 600s and in the right circumstances they perform nicely. The main problem tended to be that the components used in the early versions weren't all that good. So faults and failures were initially high. A few years into production I upgraded a lot of the components and the return rate dropped markedly. There were some things I didn't change because at the time my real focus was on the - then coming - 700 range. But even the 'noisy pot' can be fixed.

I guess they are cheap second hand for various reasons. Never have been rated as 'classic kit' by mags, etc. The early rates of faults. Now old and likely to need a checkout. Not really designed for continuous high power(1). And simply that a lot of them were made and sold, so many are probably still about, but would probably need a checkout.

(1) heatsinks for an age when music was *not* level compressed and thus had a higher peak/mean ratio than is usual for most modern popular music. Built for an age of Classical / Acoustic Jazz / Easy Listening, , not thrash metal. 8-]
 
How are they from a rebuild/ease of working on perspective Jim? Are the switches etc reliable? If they are a real sleeper this may well be the place to wake them up and get them a little more respect! How do you think a fully serviced and working correctly one compares to say the ubiquitous A&R A60 (an amp I have a lot of respect for)?
 
I've been trying to drum up interest in the 600 series for years but with little effect I'm afraid. The A60 is what I usually compare it to... as I believe I did earlier in this thread... I'll just say thermal cut-outs....

My other "hobby horse" is the Stereofetic tuner. Both the Armstrong 600 series and the Leak Stereofetic are readily available, cheaply, and will equal or beat all sorts of rival units that command respect and fetch good prices on forums etc, but it seems the opinion of a mere designer of hi fi gear counts for nothing... Of course if a hi fi journalist, probably with a degree in media studies, comes along and says they're great that would triple their rating and value overnight! Just look at what happened with the Troughline... every hi fi dealer had a pile of these in the basement and they were worth a fiver. Until a rave review in "Hi fi World" said they were the best tuner in the world! To paraphrase John Lennon, they're not even the best tuner in the Leak range! They went up from a fiver to £350 or so over night.... it's taken years for their value to come back down...
 
Tony L said:
How are they from a rebuild/ease of working on perspective Jim? Are the switches etc reliable? If they are a real sleeper this may well be the place to wake them up and get them a little more respect! How do you think a fully serviced and working correctly one compares to say the ubiquitous A&R A60 (an amp I have a lot of respect for)?
Click to expand...

I can't comment on comparisons with something like an A60. And TBH I'd tend to recommend a 625 rather than a 621 as you get a decent FM tuner as well. :)

That said, I'm happy using my old 626 with both a pair of Spendor LS3/5s and a new pair of Stirling look-alikes. The bottom end of the 600 amp output is firmer than most single rail amps of the period because the double loop helps flatten the effect of an output capacitor.

However the sets open up easily. Early models have two lever-clips for the lid and a set of 90-deg-rotate clasps for the bottom tray. The entire innards are then exposed. And the circuit + layout diagrams are available.

The details then depend on when the set was made. Early sets have poor components. Late ones have much better Alps components for switches and pots.

Afraid the detailed update notes all got skipped years before I realised info was being lost. But as a general guide people can look at the serial number on the back or pop the lid and check if the set has a 'thermal delay' or a simple tag wiring point near the mains transfomer.

Thermal delay => early set, so may have less reliable components

No thermal delay => after I went though the component list like a dose of salts and choose components that were more reliable.

It is more complex than that, but for bag-of-chips prices it may be worth a punt for someone happy to use a soldering iron. Or call on the attentions of a repair bod familiar with them.

FWIW Mike Solomons has always liked the 600s, and does a nice job of sorting out old ones . I'm still happy with

http://www.audiomisc.co.uk/Armstrong/626updated/repairandmod.html

He also fixed the main problem I never dealt with - the tendency to develop pot scrape noises particularly at switch on/off.
 
Add to the above in case it helps people:

The thermal delay is shown here

http://jcgl.orpheusweb.co.uk/temp/thermaldelay.jpeg

It, and the fuse, sit on the topside of the chassis, near the mains transformer and large capacitors.

If you look at the photo you should be able to see a high-wattage resistor on the thermal delay. If you see these, its an 'early' set in general terms. If you can't see a resistor and there is just a set of tags for the wires to connect to, it is a 'late' set and probably has the more reliable components.

Another check for sets with an FM tuner is to look at the stereo decoder. Again a general rule is that 'early' sets used an RCA stereo decoder chip. 'Later' ones used a TI chip.

The wooden lid is held by two clips hidden under the wooden sleeve at the back. They have levers you pull and rotate upwards until the clips are free. You then pull the wooden sleeve backwards until its front lip comes clear of the fascia. Then you can lift it off and all the circuits on the upper deck are exposed.

The plastic base is held by a set of plastic fastners at the back they look like buttons with an = sign on each of them. With the set upside down: Rotate them 90 degrees to unclip them and they can be pulled out. You can then lift the back of the plastic tray, then let it back so it gets free of being under the fascia. Now you can see all the circuits under the chassis. The stereo decoder is on the underside.

Usual disclaimers about "At your own risk", "Set *not* connected to mains", blah...

HTH
 
Thanks Jim, interesting stuff and it looks like you have a lovely clean one! A rather nice piece of ‘70s design really, just needs a Trimphone and lava lamp nearby!
 
I always liked the look of those back in the 1970's although I couldn't afford one then. They have a nice European/Scandinavian look and would blend in with a variety of decor.
 
Do Forum members recall the Pro-Ject 7 amplifier? I remember hearing one in Westwoods of Oxford and being
impresssed.
A few years later I bought one direct from the importer, who was dropping the Pro-Ject franchise.
The price was about half the original retail.
It had a MC phono input option, which was important for me, and sitting between my Linn LP12 and Spendor BC1s it performed very well.
I sold it a while ago and regretted it ever since...
 
Afraid that, for whatever reason, your link doesn't show me anything.

However the power amp output stage bias uses a pot and a couple of diodes (ITT44s or 1N4148s). So there isn't a 'rubber zener' bias transistor. The drivers are also some way from the output heatsinks.

I know Mike Solomon does a mod for this, but can't say what the details are. I haven't experimented because the later models tended to be more thermally stable. (Devices have higher thermal conductances, and a smoother transfer curve.) But simply putting bigger heatsinks on the drivers might help.
 
Apologies, I have made the link publicly available so it should be working. I am using MJE15030/1 drivers in mine, I assumed the 3rd to-220 device was the bias transistor. If there are two diodes I guess these can be mounted on the back of the heatsink for better thermal tracking.
 
This is my kind of thread, having no disposable income at all. But actually I cant even afford overlooked classics, rather old amps with decent phono stage for under a hundred quid.

Jez once reconditioned a Luxman L116A for me. It cost me 80 quid on gumtree and I still miss it. The phono stage was nice and it made a decent chunky sound. There is one here but he wants £200: http://rover.ebay.com/rover/1/710-5...0001&campid=5338728743&icep_item=182701681749

I guess it is mainly considered to be car boot shite, and therefore not an overlooked classic, but I liked it.

I'm also starting to appreciate the look of the black Jap stuff from the 80s, I guess I have to, if it is silver, add a hundred quid.

With Alpine Luxman, did they always put the Alpine logo on the fascia, ie Alpine Luxman? They say that was the dark age for Luxman. If I can get an LV102 for a ton, or better, L120A,I'll get it.
 
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df_genius said:
Apologies, I have made the link publicly available so it should be working. I am using MJE15030/1 drivers in mine, I assumed the 3rd to-220 device was the bias transistor. If there are two diodes I guess these can be mounted on the back of the heatsink for better thermal tracking.
Click to expand...

Have a look at the diagrams linked from

http://ukhhsoc.torrens.org/makers/Armstrong/600_Range/index.html

They include ' moderately late' and 'early' versions. (There never was a really 'late' release of the circuit diagrams, alas. ) You can see that the bias split for the drivers comes from a pair of diodes in series with a skeleton pot. In principle, yes, you could put the diodes on the back of the heatsink. But then watch out for the risk of affecting some other aspect of performance. Having long leads from the normal position to the heatsink might affect HF performance or stability. So a tight twisted pair of wires would be best I suspect. I've not tried it, so am just flagging up something that might happen. Can't say if it will, or not.

To avoid slow runaway, using a third diode with a shunt resistor to get 'two and a bit diodes' might help by overcompensating to offset the lack of a good thermal connection. But again, not tried it to find out. I settled for having better devices that reduced the effect to where it didn't matter much. And for myself I dealt with any problem when playing at high levels by the crazy method I described about a third of the way down this page

http://jcgl.orpheusweb.co.uk/history/jcmt1/MindTheGap.html

I can't recommend it, though! 8-]

To really sort it out, the boards, etc, would have neede a total redesign so the splitter, drivers, and output devices were all on the same heatsink. At the time it was felt simpler just to design a new amp as that was needed anyway. In normal use (as envisaged back then) the existing design was OK given decent devices.
 
I will never forget hearing my first Arcam Alpha 2 at Derek Whittington's in Loughborough when my then girlfriend and I went to audition some kit for her . Derek played one of his own records, a version of Peter and the Wolf, and to us the combination of the Alpha driving a pair of Kans and using an LP12 sounded perfect - so much so and so she bought the whole kit! We listened a lot to that system and as time went became most dissatisfied with the sound from my own amp. I could not afford a total system upgrade that but did have at home a Sansui SR222 turntable and a pair of Mk1 Strathearn speakers which badly needed something decent to drive them and so some time later did fork out for the same model Alpha amp - which I still have and use to this day albeit as a second system. For sheer value for money to me at the time it rated very highly - and still does!
 
Joddle said:
I will never forget hearing my first Arcam Alpha 2 at Derek Whittington's in Loughborough when my then girlfriend and I went to audition some kit for her . Derek played one of his own records, a version of Peter and the Wolf, and to us the combination of the Alpha driving a pair of Kans and using an LP12 sounded perfect - so much so and so she bought the whole kit! We listened a lot to that system and as time went became most dissatisfied with the sound from my own amp. I could not afford a total system upgrade that but did have at home a Sansui SR222 turntable and a pair of Mk1 Strathearn speakers which badly needed something decent to drive them and so some time later did fork out for the same model Alpha amp - which I still have and use to this day albeit as a second system. For sheer value for money to me at the time it rated very highly - and still does!
Click to expand...
I had one of those and quickly upgraded to the 290 pre and power combo, which for the money difference, was disappointing. I think I thought it was faking proper kit a bit, because you bought the 290 integrated I think and then bought the power amp, turning the integrated into a pre. I bet I'd like that setup now.
 
Early DD turntables, with the exception of technics which are popular. I have a Sony which is great, but I've seen impressive decks from pioneer, Kenwood, Denon etc.
 
Onix OA20 ?

Built like a tank, lovely styling imo, still working beautifully - not sure if it qualifies as a "classic" but must be about 30 years old now. Is that old enough/popular enough/enough made to qualify as a classic?
 
I’d say so. I’ve got a lovely OA21S on the subs bench and it is a really nice amp, and they have held their value well.
 
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