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Old 2nd Nov 2017, 4:52 pm   #1
Goodizzy
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Default EMI DLS-1 / STD 373-DLS column speakers

Good afternoon,

I recently purchased a pair of EMI DLS-1 column speakers, (as shown in the picture) and was wondering if anyone had a schematic for the amplifiers which drive them? (EMI STD 373/DLS)

There is scant information regarding these on the internet, but as much as I can tell from diagramming bits of the circuit is they are a variant on the Mullard 5-20. They appear to have trimpots, however, in the output stage and the HV power supply is all RC without a choke.

They are very well built, with shielding over the PT and fairly excellent lead dress. I imagine the OTs are also of a high quality as STD manufactured the amps to be in compliance with EMI standards.

I appreciate any insight you may be able to provide!
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Old 2nd Nov 2017, 5:18 pm   #2
Edward Huggins
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Default Re: Emi dls-1 / std 373-dls

Just to add to this, the amplifier was mounted in the base. An early example of an active speaker. I mention this as some Members may assume that the amplifier is a separate externally used chassis.
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Old 2nd Nov 2017, 6:14 pm   #3
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Default Re: EMI DLS-1 / STD 373-DLS column speakers

Thank you Edward, I should have mentioned that. Here is another photo of one of the amplifier's underside.
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Old 2nd Nov 2017, 7:47 pm   #4
Edward Huggins
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Default Re: EMI DLS-1 / STD 373-DLS column speakers

Having worked for EMI, I regret not researching these better at the time.
I have often wondered whether these amplifiers, and the superb "Superscope" Stereo amplifiers, were built by a Third Party under contract? They they just do not look like EMI commercial construction and they were also very rarely influenced by any Mullard designs.
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Old 2nd Nov 2017, 9:51 pm   #5
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Default Re: EMI DLS-1 / STD 373-DLS column speakers

Edward,

I have been after a pair of these for around three years now. All of research I've done is through the internet, forums and older radio magazine advertisements. I have a folder of pictures and information regarding these and I'll see if I can pull up what I have.

Edit: (Advert? Info)

"Emisonic EMI orthotone STD 373/DLS 25 watt ultra-linear KT 77 (EL 34) Push/Pull tube mono block amplifier as fitted in the active EMI DLS-1 speaker, 0.1% THD, 4, 8, 16 ohm taps, EF 86, ECC83, GZ34 rectifier, special output transformers, rated superior to Leak TL 25 plus (built into REDD.36 in UK)"

I had read that they were based on the Mullard 5-20, but that was based on a passing remark in a forum post. Certainly the PSU is NOT Mullard's design but I haven't finished drawing out a schematic so I can't say for sure how similar the two are.

Each cab has an EMI elliptical driver (92390G) and (2) GEC BCS 1853 drivers. There is a certain eBay guide to these elliptical drivers and this version appears to be one of the highest quality. Then again, hi-fi standards of the time were lower and IIRC these drivers response only extended to about 15kc/s. What IS interesting is that studio playback speaker at EMI/Abbey Rd used these drivers with the addition of a Wharfedale 15" bass unit to create the RLS10/11 or White Elephant speakers.

I also own a Leak TL/25+ modified to REDD.C36 which has a few changes made in-house at EMI. Most notably the addition of a type B jack and associated rotary knob for quickly checking voltages.
Also, the mains fuse was switched to HV- my guess being that the amp was housed inside another chassis with mains fuse, mains switch and input transformer. 200 ohm line standard, no?

This is all from memory, so I would have to go back and look at my research and files to make sure I'm all correct here. Since you worked there you are probably much more enlightened!

Out of curiosity what did you do for EMI?

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Old 3rd Nov 2017, 10:51 am   #6
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Default Re: EMI DLS-1 / STD 373-DLS column speakers

I was the PR Manager. I took full advantage of my time there to regularly visit their record Vaults and meet with the Curator, see the original Nellie Melba acoustic recording studio, and learn as much as possible about eveythnig from the HMV800 Radiogram to their then flourishing speaker range.
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Old 3rd Nov 2017, 10:57 am   #7
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Default Re: EMI DLS-1 / STD 373-DLS column speakers

The HMV stereoscope etc were built by Clarke & Smith. Ultimately the amps were just badged 'CSI'.
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Old 3rd Nov 2017, 11:06 am   #8
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Default Re: EMI DLS-1 / STD 373-DLS column speakers

Quote:
Originally Posted by Edward Huggins View Post
Having worked for EMI, I regret not researching these better at the time.
I have often wondered whether these amplifiers, and the superb "Superscope" Stereo amplifiers, were built by a Third Party under contract? They they just do not look like EMI commercial construction and they were also very rarely influenced by any Mullard designs.
I believe that the EMI Superscope equipment was built under contract by Clarke & Smith, of school radio fame.

The Superscope pre-amp was the core of my first stereo system. The one-inch CRT display of the stereo separation was intriguing and entertained my fellow students.

I still have that pre-amp in full working order and more recently acquired the version incorporating a pair of 2xEL84 10-watt power amps. That had suffered from some overheating - it lacked sufficient ventilation for the prodigious heat output in a rather compact layout. A few component replacements soon restored it to working order and opening up more ventilation grilles has hopefully eliminated overheating. I believe that they're rather sought after today.

It's interesting that around 1960, EMI made a noble attempt to rival the big hi-fi names like Leak and Quad. Some of the best stereo sound I've ever heard came from EMI kit - possibly from these 'column' speakers.

Interestingly, you could buy an EMI version of every part of the disc playing chain, including their rather good magnetic stereo pickup head and arm. However, their audio sales must have been disappointing - in the domestic market the EMI name sank without trace, which is how I came to buy my Superscope pre-amp relatively cheaply on the surplus market in the early 1960s.

Martin
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Old 3rd Nov 2017, 3:24 pm   #9
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Default Re: EMI DLS-1 / STD 373-DLS column speakers

Thank you for the reply. It is difficult on this side of the pond to find information regarding British hifi during this period. In fact, I wouldn't be surprised if I was one of the only ones with an interest in it over here. An anglo-audiophile of sorts!

Here is an advert I found online which details some of the Orthotone amps STD built for EMI. I have yet to find any schematics or even pictures on the internet of the STD kit that I could use to diagram a schematic. I assume time, and as you said- a non-interest among the domestic market to account for the lack of information. I would certainly have an interest in building all of these amps!

I wonder if there is similarity between the C&S 10W EL84 amp and the STD-381? Different companies, I know, but its interesting EMI only subcontracted to these two.
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Old 3rd Nov 2017, 5:12 pm   #10
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Default Re: EMI DLS-1 / STD 373-DLS column speakers

Of course........for Superscope, read Stereoscope!

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Old 3rd Nov 2017, 8:34 pm   #11
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Default Re: EMI DLS-1 / STD 373-DLS column speakers

Quote:
Originally Posted by Hartley118 View Post
Interestingly, you could buy an EMI version of every part of the disc playing chain, including their rather good magnetic stereo pickup head and arm. However, their audio sales must have been disappointing - in the domestic market the EMI name sank without trace, which is how I came to buy my Superscope pre-amp relatively cheaply on the surplus market in the early 1960s.
Are you thinking of the EMI unipivot tonearm with a Decca style moving iron cartridge, Martin? I had one for a while - sadly it was badly damaged and I never got it going, but it looked like a really good thing.
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Old 4th Nov 2017, 12:19 am   #12
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Default Re: EMI DLS-1 / STD 373-DLS column speakers

I would say sort after I had one in 1969 one of my greatest regrets in selling it a wonderful amplifier. "Here comes the sun" from Abbey Road has never sounded so good. British at its very best.

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Old 27th Nov 2017, 3:08 am   #13
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Default Re: EMI DLS-1 / STD 373-DLS column speakers

Hi
My first post... I am lucky to own a pair of Emi Dls-1 towers.

I have a schematic for the std 373 so feel free to contact me. I was fortunate to make friends with a retired tech from Jardis who also went into business with Stereophile, Gordon holt. We ( well he) rebuilt the amps, They work great and during a test he said they had the flatest response of any thing he ever tested. We were both stumped by the ( crossover/ contouring ) screws .
The speakers have a wonderful floating sound stage. I also have the marketing sheet for these speakers.
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Old 27th Nov 2017, 6:54 pm   #14
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Default Re: EMI DLS-1 / STD 373-DLS column speakers

Some background on C&S and STD here (page 12):

http://www.ferrographworld.com/pdf/A...20Bulletin.pdf

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Old 28th Nov 2017, 7:01 pm   #15
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Default Re: EMI DLS-1 / STD 373-DLS column speakers

Fantastic replies gents. I much appreciate the schematic offer- it will help immensely!

Wd40addict, that link was very interesting. Much infromation gained! I have browsed that website before but had never seen this.
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Old 3rd Mar 2018, 9:23 am   #16
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Default Re: EMI DLS-1 / STD 373-DLS column speakers

Quote:
Originally Posted by Jchefss View Post
I have a schematic for the std 373 so feel free to contact me. I was fortunate to make friends with a retired tech from Jardis who also went into business with Stereophile, Gordon holt. We ( well he) rebuilt the amps, They work great and during a test he said they had the flatest response of any thing he ever tested. We were both stumped by the ( crossover/ contouring ) screws .
The speakers have a wonderful floating sound stage. I also have the marketing sheet for these speakers.
Hi, i have too a pair of DLS-1 but without amplifiers, if you can send the schematic of STD373, i would like to try the DIY way first.
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Old 20th Mar 2018, 1:21 pm   #17
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Default Re: EMI DLS-1 / STD 373-DLS column speakers

I put some pictures here :-

https://www.vintage-radio.net/forum/...37#post1027837

Maybe someone can help me with diagrams of tube amplifier STD373? I still need them.
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