Powering very old speakers

[KEW]

I just got an email from an old friend:

Thanks to the "Dirty Santa" gift exchange at the mountain bike club party we hosted Friday night, I now have an Atwater Kent Model E loudspeaker, manufactured circa 1927.

This link is to a video showing the Model E (and accompanying radio):
http://www.youtube.com/watch?v=gxVcfXeOOaA&feature=related

Also, FYI, here's a link to a look 'n' listen session with several cool vintage loudspeakers, including a Model E (but it doesn't sound as good as mine): http://www.youtube.com/watch?v=WgCqGWFJvHk&feature=related

The Model E has a DC resistance of about 690 ohms, so to get decent volume from it I have to crank my ol' Dynaco ST-150 WAY up 'til it's clipping. I'm hoping the fix is as simple as wiring up a cheap audio transformer (like this $3 item from Radio Shack: http://www.radioshack.com/product/index.jsp?productId=2103254 ) opposite the usual way so as to step up my amp's output voltage and lower the current required. The RS unit apparently rolls off south of 300 Hz, but I doubt the Model E does much business down that low anyhow.

I just want to be able to play the old Model E for grins & giggles without blowing a fuse (or an output transistor) - and suggestions?

I'm pretty clueless on this.
Is he on the right track?

Thanks,
Kurt

 

[highfigh]

I just got an email from an old friend:


I'm pretty clueless on this.
Is he on the right track?

Thanks,
Kurt

If the amplifier is designed to see a load like that, it's only going to work well with that amplifier, or one like it. Keep looking into this speaker and you'll find more specs, like whether that's the correct reading. Over time, it's possible that the solder joints have gone bad but I don't know if the reading you got is what it was, originally.

 

[TLS Guy]

I just got an email from an old friend:


I'm pretty clueless on this.
Is he on the right track?

Thanks,
Kurt

No he is not on the right track.

Like a lot of old radios the AK radios of the period were OTL types. Although the audio tubes were transformer coupled there was no output transformer and the speaker was connected directly to the output tube.

Not only that but the resistance the tube needed to see was in the 500 to 1000 ohm range, which is much lower than modern tubes which like to see 2.5 kohms.

So an output transformer will not work. He needs to find and restore an Atwater Kent radio that was designed to power his model E.

Here is the circuit.

 

[KEW]

OK, Thanks!

So the consensus is that he really needs to match it to the radio (amp) it was designed to mate with. I did notice that the radios are more common than the speakers according to one of the utube clips.

Hopefully he can find one on the cheap - this is more of a novelty exercise than a collector project.

Even though it is not the correct way, is there any little tweak he can make to a normal amp to slightly improve suitability or is this a path of certain doom? If the latter, is the speaker or the amp most at risk?

As he puts it, he just wants to fire up the thing every now and again for "grins and giggles".

 

[highfigh]

OK, Thanks!

So the consensus is that he really needs to match it to the radio (amp) it was designed to mate with. I did notice that the radios are more common than the speakers according to one of the utube clips.

Hopefully he can find one on the cheap - this is more of a novelty exercise than a collector project.

Even though it is not the correct way, is there any little tweak he can make to a normal amp to slightly improve suitability or is this a path of certain doom? If the latter, is the speaker or the amp most at risk?

As he puts it, he just wants to fire up the thing every now and again for "grins and giggles".

It would be best to match it with the correct radio and since they're available, it's not out of the question unless it's really expensive. It will need to be checked out and any electrolytic caps will need replacing, frayed cloth insulated wires repaired, etc, but the tubes should be easy enough to find if one or more is bad.

As far as your last question re: which is st risk more, I would say "Both". If the speaker fails with a shorted voice coil, it will take out the amp and if the amp fails in certain ways, the speaker will be no more than a paper weight.

Here's one that's only at $24.99-
http://cgi.ebay.com/1926-ATWATER-KENT-35-BATTERY-SET-RADIO-NICE-NR-/160518858279?pt=LH_DefaultDomain_0&hash=item255fab6627

 

[TLS Guy]

OK, Thanks!

So the consensus is that he really needs to match it to the radio (amp) it was designed to mate with. I did notice that the radios are more common than the speakers according to one of the utube clips.

Hopefully he can find one on the cheap - this is more of a novelty exercise than a collector project.

Even though it is not the correct way, is there any little tweak he can make to a normal amp to slightly improve suitability or is this a path of certain doom? If the latter, is the speaker or the amp most at risk?

As he puts it, he just wants to fire up the thing every now and again for "grins and giggles".

The problem with this whole affair, is we have someone with no knowledge of what they are doing wanting to use something old, fragile and rare.

If he buys the AK 35 he will have restoration. He will need a battery eliminator. Batteries to drive these old radios are no longer available. It used to have a lead acid accumulator to drive the filaments, and HT batteries of different voltage. He will have to know what voltage goes where and how to set up the battery eliminator for that particular unit.

He will be dealing with voltages of around 67 volts, 22 volts and 5 volts.

The unit is going to require some restoration before it can be used.

Next the speaker is frail. I understand it is some type of reed speaker, that were around between the moving iron and moving coil speaker era. The speaker coil is wound with very thin wire and easily burnt out. My best guess is that the speaker handles about 1.5 to 3 watts. From the HT voltage probably a little under three watts.

What he could do to drive it from his Dyanco is to find a 10/1 ratio transformer of 3 to 5 watts capability. I would look for something with 100 turns on the primary and 1000 turns on the secondary. The low turn side would be the primary and go to the Dynaco. The high turn secondary would go to the speaker. Even though it is low powered there will be 50 volts going to the speaker, so be careful. So as not to blow the speaker I would put a 0.5 amp fast blow fuse in series between the transformer secondary and the speaker, so he does not blow it.

 

[KEW]

Thank you, sir!

 

[tom67]

solution

I just got an email from an old friend:


I'm pretty clueless on this.
Is he on the right track?

Thanks,
Kurt

Get a smaller new radio and hide it behind the old one....experiment with placement so it sounds like sound coming from old unit...

 

[KEW]

Get a smaller new radio and hide it behind the old one....experiment with placement so it sounds like sound coming from old unit...

...and hide a small subwoofer under the desk!

 

[ski2xblack]

It seems a crime to actually risk damaging such a rare antique. What's the point of firing it up, other than hear how bad primordial sound reproduction was, while risking the value of the item?

But if he's willing to risk it and not restoring one of the original radios, what about a tube/OTL headphone amp of some sort? Maybe, just maybe, if one can be found with similar specs to the original radio, such a device would reduce the risk frying that old speaker. I still wouldn't do it.

 

[KEW]

It seems a crime to actually risk damaging such a rare antique. What's the point of firing it up, other than hear how bad primordial sound reproduction was, while risking the value of the item?

But if he's willing to risk it and not restoring one of the original radios, what about a tube/OTL headphone amp of some sort? Maybe, just maybe, if one can be found with similar specs to the original radio, such a device would reduce the risk frying that old speaker. I still wouldn't do it.

I guess it is all a matter of perspective.
Functionally, this is a crappy old speaker.

You apparently see value in it being a rare crappy old speaker.

My friend sees value in it as a novel crappy old speaker that cost him nothing and might perform its original function with a minimal investment of time and money. I believe (success or fail) he also considers it a fun experience to adapt it to modern electronics (and see some interesting twists in antique speaker construction/design).

Others (like the guy who gifted it) see no value in it as a worthless crappy old speaker!

Cheers,
Kurt

 

[TLS Guy]

I guess it is all a matter of perspective.
Functionally, this is a crappy old speaker.

You apparently see value in it being a rare crappy old speaker.

My friend sees value in it as a novel crappy old speaker that cost him nothing and might perform its original function with a minimal investment of time and money. I believe (success or fail) he also considers it a fun experience to adapt it to modern electronics (and see some interesting twists in antique speaker construction/design).

Others (like the guy who gifted it) see no value in it as a worthless crappy old speaker!

Cheers,
Kurt

That is a very American perspective and misguided.

The fact it sounds crappy is irrelevant. It is a rare artifact of our technological and industrial past. It needs to be respected and not abused.

Unless items like this can be approached with due reverence, then they should be donated to museums with expert restorers for future generations to see and learn from.

I would be more than happy to arrange for it to be added to this excellent museum collection.

 

[KEW]

Is it an American perspective to see it as novel, or as worthless?

Or do you mean I have an American perspective for recognizing the range of perceived value something like this has to different people?

Thanks for the museum option, I will pass it on!

 

[TLS Guy]

Is it an American perspective to see it as novel, or as worthless?

Or do you mean I have an American perspective for recognizing the range of perceived value something like this has to different people?

Thanks for the museum option, I will pass it on!

I think it is a paradox. If you live amongst a lot of ancient buildings and artifacts, the respect is the greater.

America is a young county. It is a country that has a hard time preserving the past. The wrecking ball is used with far too much abandon, which leads to a rootless society in my view. It also encourages the building of junk on all fronts. Case in point that Metrodome Football stadium in Minneapolis. The roof ripped, because it was junk on the drawing board. Its now referred to by one and all as an aging facility. Its only 28 years old! Let me remind you that the Coliseum in Rome still stands!

I suspect that speaker may be better than you think. Even on a recording via YouTube it seemed to have good voice clarity.

I have frequently had to reach for my old Model A to do unexpected jobs. To the unfamiliar their first assumption is it won't start and be any use.

They quickly get a lesson, as it starts quickly with virtually no cranking; first piston to compression as a rule. It hen proceeds to get the job done. It just never astounds me how people assume something is no good.

My vintage turntables are another case in point.

That AK speaker has survived and is now due the respect of the venerability of its age.

 

[highfigh]

I think it is a paradox. If you live amongst a lot of ancient buildings and artifacts, the respect is the greater.

America is a young county. It is a country that has a hard time preserving the past. The wrecking ball is used with far too much abandon, which leads to a rootless society in my view. It also encourages the building of junk on all fronts. Case in point that Metrodome Football stadium in Minneapolis. The roof ripped, because it was junk on the drawing board. Its now referred to by one and all as an aging facility. Its only 28 years old! Let me remind you that the Coliseum in Rome still stands!

I suspect that speaker may be better than you think. Even on a recording via YouTube it seemed to have good voice clarity.

I have frequently had to reach for my old Model A to do unexpected jobs. To the unfamiliar their first assumption is it won't start and be any use.

They quickly get a lesson, as it starts quickly with virtually no cranking; first piston to compression as a rule. It hen proceeds to get the job done. It just never astounds me how people assume something is no good.

My vintage turntables are another case in point.

That AK speaker has survived and is now due the respect of the venerability of its age.

If the Europeans who came here for a new life hadn't been escaping whatever they were, I think preserving the past would have been a minor goal. The fact that they wanted a new life means they didn't want anything to do with their past and didn't want reminders of it, although some carried on some of their traditions. If they had, everything they built would have been done the same way and would have looked the same, or similar. Ironically, they didn't leave their attitudes about conquering the native people behind.

The Metrodome wasn't built to last, the Coliseum was. Also, what is now missing from the Coliseum was scavenged and it was used as a dumping ground after the Roman Empire fell.

The Romans didn't have structural steel or fiberglass, either. If they had, think of what they could have had- light weight fiberglass columns on the great buildings, no need for slave labor (the materials would have been much easier to move and erect), much longer spans and larger open indoor spaces, skylights without rain coming in and possibly those tulip chairs designed by Saarinen.

I agree completely- the "disposable goods" idea is offensive. I don't like to see intact musical instruments and other items dismantled so they can be sold off as parts, just to make a bit more money. This speaker isn't "junk", because it may still work. If it does, I think it should be matched with a radio of similar vintage. That's the reason I posted the link to that one on ebay. I like to make things better than they were when I got them- that's why I bought my Oahu lap steel guitar amp (which sounds great, BTW), all of my old hand tools, some of my instruments and some of my furniture. Cheap, modern crap is just that. Just being modern doesn't necessarily make anything better, it just makes it newer.

 

[KEW]

This speaker isn't "junk", because it may still work.

If you read the original post, it does work - he has already played it!
However, his Dynaco ST-150 was clipping before the speaker was at a decent volume.

I passed on the information about the museum and he was kind of surprised that people here thought it was especially rare.

He has the impression (from looking at some antique radio websites) that these speakers are not particularly rare, i.e. pretty much every antique radio buff who wants one has one, and they keep turning up in estate sales. Evidently they were a popular item back in the day.

I think he is right. There are 7 of these speakers currently for sale on eBay:
http://shop.ebay.com/?_from=R40&_trksid=p5197.m570.l1313&_nkw=atwater+kent+model+E&_sacat=See-All-Categories

 

[TLS Guy]

If you read the original post, it does work - he has already played it!
However, his Dynaco ST-150 was clipping before the speaker was at a decent volume.

I passed on the information about the museum and he was kind of surprised that people here thought it was especially rare.

He has the impression (from looking at some antique radio websites) that these speakers are not particularly rare, i.e. pretty much every antique radio buff who wants one has one, and they keep turning up in estate sales. Evidently they were a popular item back in the day.

I think he is right. There are 7 of these speakers currently for sale on eBay:
http://shop.ebay.com/?_from=R40&_trksid=p5197.m570.l1313&_nkw=atwater+kent+model+E&_sacat=See-All-Categories

You know the fact that there are so many of those units still around, speaks volumes. I be the production numbers were tiny as you had to be very savy and tech inclined to operate one of those old radios.

I would bet the total production of those speakers was less then one months shipment of a given model number of an Onkybust or Yamablow receiver.

It is like old Quad amps. The production numbers where tiny compared to today's numbers. Yet 40 or more years on, you will have no trouble picking up a 303/33 combo. Far more likely than not it will work perfectly and the case has probably never been opened. It is estimated that in excess of 80% of the products designed by Peter Walker are still in regular use.

 

[highfigh]

They weren't that rare. Here's a quote from a thread in an antique radio forum-
"Model 20- 189,770 (big box)
Model 19- 5,698
Model 21- 10,366 (7,200 recalled & modified to be 20C's)
Model 20C- 163,257"

and here's the link- http://antiqueradios.com/forums/viewtopic.php?t=152758

From Wiki, "At its peak in 1929, the company employed over 12,000 workers manufacturing nearly one million radio sets. Its models included the metal-cabinet seven-tube Model 57 at US$105 the wooden-cabinet eight-tube Model 60 at US$80.[9] The plant itself was an architectural sensation and received hundreds of visitors annually.[10] By 1931 the company boasted that it had produced over three million radios.".