Is it worth repairing?

If it is possible to repair and it can be used after, it is worth repairing, it's fun and sustainable.

Not many valve set qualify for sustainable given their energy consumption, 1970's transistor set however only sip at the current. Modern stuff simply eats away at power, are we going backwards?

[avocollector]

One of the things I've noticed is that some similar hobby areas to radios which use valves have become highly collectible and thus have started to have specialist dealers. For example old valve amplifiers for guitars made by Fender, Marshall etc etc are desirable and still used for their particular sound. This means the valves for them KT88's 12AX7's EL34, 5Y3's are in demand and modern ones (still made in China and Russia I understand) cost about $34 - about the same as you'ld expect from normal cost increases from the old days - say 60's when a valve cost 37/6d. Unfortunately a lot of musicians are not particularly rational and regard the original unused stock from Phillips, Brimar and so on as better quality and supplying better 'tone' than the modern valves. Hence they are willing to pay large amounts for this original stock, just as they are willing to pay 5-10 times the price of a modern electric guitar to get something from the 60's.

This in turn has led to people setting themselves up as dealers in valves primarily to supply the musos with boxed original stock - and of course make a large profit for themselves in the process. Most will be in this area with mercenary intent and unlike the collectors will 'charge like wounded bulls' as the saying goes. Such is the nature of the beast.

I find this particularly irrational in view of the fact that any original amplifier from the 50's will have had capacitors, resistors, possibly transformers and speakers and even other parts replaced over time with more modern equivalents and hence any magical 'tone' inherent in the construction will be long altered but there are those fixated on the idea. There is a slight bit of rationality in that the modern Chinese KT88 (or 66; I cannot remember which) cannot handle the high voltages in some old Marshall amps (the 200watt model was particularly bad for this) and can actually explode, hence their modern nickname 'firecrackers'. But otherwise most modern replacements do a good job.

So the hobby's economics are altered not just by us radio enthusiasts but also by others using the same technology/competing for the same valves - sadly that seems to be life. But to my mind the emotional worth of doing the repairs far outweighs the financial aspect.

[stevehertz]

Originally Posted by avocollector

Unfortunately a lot of musicians are not particularly rational and regard the original unused stock from Phillips, Brimar and so on as better quality and supplying better 'tone' than the modern valves. Hence they are willing to pay large amounts for this original stock, just as they are willing to pay 5-10 times the price of a modern electric guitar to get something from the 60's.

Well, as I have a foot in both camps; a time served electronics engineer with over 40 years vintage experience, AND a lead guitarist who has played around with (dismantled, fixed, modded, refurbished) just about every vintage Marshall, Boogie, Fender, Selmer, etc etc that you can name, I can tell you categorically that different brands of valves in guitar amps sound much different than they do in other apps. The reason? guitarists drive them into distortion to a greater or lesser degree. In this mode, the difference in "tone" is incredible. Now I'm sounding like an audiophile going on about cables or something! No, seriously, the difference is HUGE. In short, a Mullard ECC83 will distort with sweet, musical, 'harmonically rich' overtones, but some of the more naff Chinese examples sound like a cheap fuzz box; discordant, sour, jagged, spikey, fuzzy - just awful. I wouldn't have believed it myself - and I didn't for many years until I tried it - but trust me, it's not irrationality, it's fact! The world or hobby of 'electric guitar amps' - like our hobby here - can be niche and have its own 'difficult for others to understand' idiosyncrasies, it doesn't mean that the people are irrational or (not that anyone said it), stupid. No, guitarists know "tone" when they hear it, and good quality, vintage valves produce great tone.

[christge]

Originally Posted by ukcol

Sourcing general parts like capacitors and resistors is straight forward and obtaining cosmetic parts and electronic parts unique to a model can be more challenging but that's part of the fun.

I find the "treasure hunt" aspect of the hobby one of the enjoyable parts myself. So pleased when I have that "aha" moment!

[high_vacuum_house]

That's what I enjoy going to the ham radio fairs. If you are willing to kneel on the grass rummaging in boxes of old valves and components you can sometimes get a surprise like finding 2 nearly new 5 pin + side contact AC/pen's for a pound each.

Often you meet other people rummaging in the boxes and you find they are restoring the same sort of equipment as your interests and then you have a good chat about restoration ECT over a cup of tea.

I find restoring valve equipment is not as expensive as some people think if you are willing to take the time to go to radio events get your hands and knees dirty and meet people. Other than the usual capacitors most sets wont really require much more expense unless you are unlucky to have a failed transformer. Cabinet work can be relatively cheap if its a Bakelite case. wooden radios depending on condition are not that expensive to work on, they just need plenty of patience and time to get right.

I have only come across a few valve failures and I cannot see any reason to replace all the valves with NOS ones in a radio all in one go as part of a restoration. Most will still have many hours of life left even if their emission is falling. The reliability of most valves is staggering with many doing 1000's hours service on the original valves and still the set works well. With the exception of a handful of valves most mid 30's and onwards valves are still available at a reasonable price. PX4 and other triode output valves are ludicrously expensive though conversely there are not too many radio sets with these valves in. As long as the valve stripper hasn't got to it first, its valve should be there and most likely in a working condition.

Christopher Capener

[Scimitar]

Originally Posted by high_vacuum_house

then you have a good chat about restoration ECT over a cup of tea.

What's an ECT?

[Nymrod121]

I read it as "etc."

[a slip of the 'caps lock' key, maybe?]

[Herald1360]

Originally Posted by Scimitar

What's an ECT?

What you get if you poke your finger in the wrong place in a valve set

[christge]

I myself love this hobby. I often spend more than a radio is worth in value because of the enjoyment and other benefits I get. Absolutely understand that it may not be worth it to others, in which case it might be a good idea to reevaluate what one really wants to achieve.

Geoff

[Boater Sam]

Perhaps you have seen this?
https://www.vintage-radio.net/forum/...ad.php?t=95955

I fix radios because I want to. Simples.

[Hartley118]

Originally Posted by stevehertz

Well, as I have a foot in both camps; a time served electronics engineer with over 40 years vintage experience, AND a lead guitarist who has played around with (dismantled, fixed, modded, refurbished) just about every vintage Marshall, Boogie, Fender, Selmer, etc etc that you can name, I can tell you categorically that different brands of valves in guitar amps sound much different than they do in other apps. The reason? guitarists drive them into distortion to a greater or lesser degree. In this mode, the difference in "tone" is incredible.

...........guitarists know "tone" when they hear it, and good quality, vintage valves produce great tone.

I think you've made a very interesting point here Steve. It's worthy of a thread all of its own. You're raising the subject of amplifier behaviour under abnormal conditions. This can also be relevant to the early stages of studio mixing desks because of the big transients which can come from microphones on live instruments. Clean clipping and fast overload recovery are important.

Careful circuit design is important, particularly the position of coupling and decoupling capacitors which can charge up and affect DC bias conditions. What intrigues me about your experience is that different valve examples can change overload behaviour. I can understand that changes of bias conditions would affect the behaviour of different valves in a different way. However, I'd have expected that a (literal) Chinese copy of an ECC83 would behave identically to the Mullard design which it copied.

I guess that the first question is just which stage of a guitar amplifier tends to clip first. Is it the power output stage, or somewhere else? Then,what's the impact of any feedback loop behaviour when the open loop gain has been driven to zero by clipping?

Steve - As an experienced engineer, have you any theory as to how different valve examples might vary sufficiently to make such an audible difference?

Mods - Apologies that this is moving OT. maybe it belongs somewhere else.

Martin

[avocollector]

Apologies if my claims of musician irrationality upset people, but my main point was that there were more than just radio hobbyists pursuing the old valve stock (saw some old stock ECC83's being offered for $100+ a pair today on the local internet auction site) which will affect the economics of repair.

Mind you one lovely example of musician 'behaviour' I came across a few years back was a liquid being offered at some huge sum. Apparently the idea was if you painted this onto the integrated circuits in your amplifier, it would then sound like a valve amplifier. It was aimed at guitarists and presumably someone thought they would buy it in large enough quantities to have bottles of the stuff made up. I rather regret not buying it and having it analysed.

[electrogram]

It was probably snake oil

[Refugee]

Varnish sols as snake oil?

[Station X]

Back on topic please.

[stevehertz]

Originally Posted by Hartley118

I think you've made a very interesting point here Steve. It's worthy of a thread all of its own. You're raising the subject of amplifier behaviour under abnormal conditions. This can also be relevant to the early stages of studio mixing desks because of the big transients which can come from microphones on live instruments. Clean clipping and fast overload recovery are important.

Careful circuit design is important, particularly the position of coupling and decoupling capacitors which can charge up and affect DC bias conditions. What intrigues me about your experience is that different valve examples can change overload behaviour. I can understand that changes of bias conditions would affect the behaviour of different valves in a different way. However, I'd have expected that a (literal) Chinese copy of an ECC83 would behave identically to the Mullard design which it copied.

I guess that the first question is just which stage of a guitar amplifier tends to clip first. Is it the power output stage, or somewhere else? Then,what's the impact of any feedback loop behaviour when the open loop gain has been driven to zero by clipping?

Steve - As an experienced engineer, have you any theory as to how different valve examples might vary sufficiently to make such an audible difference?

Mods - Apologies that this is moving OT. maybe it belongs somewhere else.

Martin

Martin, you flatter me referring to me as an experienced engineer - albeit probably my own words originally! TBH, I know little or nothing about valve amp theory. In that respect my knowledge is 'limited' to working on guitar valve amps in a somewhat staid, step by step manner when fault finding or restoring them. But when it comes to evaluating them, their sound, I have spent hundreds if not thousands of hours doing A/B tests, lots of stuff. Mullard valves just seem to distort in a very agreeable, sweet, rich, musically pleasing way. The cheapest imported valves sound like a major amp fault when driven into distortion territory. In fact, although manufacturers don't generally use those very cheapest valves, I'm told that the mid ranging (still far eastern imported) valves that they use still requires them to voice the amp's design so as to counter their harshness. Drop a Mullard in there and you have harmonic heaven! Now you see why guitarists will pay tens of pounds for a single valve (chicken feed when compared to what they do spend on kit) to get a great sound.

[MitchMag]

I am a new member here and know very little about electronics, so do not have the knowledge to repair some of the items I acquire.

I have an interest in vintage items for their historical value, workmanship and aesthetics so they are worth saving. These include clocks, radios, phones and record players.

I clean them, try to get them working and use them as display items.

[Ed_Dinning]

Hi Mitch, with the assistance of the forum members you should, given time, be able to fix up many more of your acquisitions.
Post your problems here and we will try to help.
There are now quite a few forum members in the NE

Ed

[MurphyNut]

Originally Posted by MitchMag

I am a new member here and know very little about electronics, so do not have the knowledge to repair some of the items I acquire.
I have an interest in vintage items for their historical value, workmanship and aesthetics so they are worth saving. These include clocks, radios, phones and record players.
I clean them, try to get them working and use them as display items.

If you want to collect these lovely things from a bygone age you'll want to learn about them and how to restore them.
I've not had any electrical background but I've spent countless hours on the internet soaking up information and asking questions and now I spent very enjoyable time fixing sets.
The original post here does miss the point, a hobby such as this doesn't have to be justified as being cost effective or worth doing.
Even saying that I think it represent remarkably good value, it can be enjoyed on so many levels, components don't cost much and there's lots of lovely sets still to be had cheap.
Look at how much people are prepared to pay out on the average football season ticket or golf club membership!

[dave walsh]

I agree with your views Clive. Although I think that this thread began with some very inaccurate and unsupported assumptions, it started a very good discussion about what's possible? why we are doing it? and relative values in general. Of course it's possible to pay as much as you like for anything and high value items exist [the retro craze has contributed] but in general, enthusiasts enjoy creating/restoring something with ingenuity, cooperation and minimum cost. This is very much the ethos of Amateur Radio as well and a great attraction.
Unfortunately it's not always understood, as we have seen quite recently

Here on the coast [from the bar] I see people enjoying a low cost sailing hobby in small boats that cost very little and are self maintained by completely ordinary individuals working together yet there is still a [diminishing] belief that sailing requires a particular social standing and deep pockets. Maybe at the Regatta-I do know of one seaside town that has two Clubs [one for the "elite"] but generally the hobby is accessible by anyone at all of good character and intent.

Dave W