Parts Identification - The Daven Company - diyAudio
Go Back   Home > Forums > Design & Build > Parts

Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 10th January 2012, 01:20 AM   #1
elizard is offline elizard  Canada
diyAudio Member
 
Join Date: Mar 2003
Location: Winnipeg, MB
Send a message via MSN to elizard
Default Parts Identification - The Daven Company

Received an old piece of test equipment today (not sure what it is though to be honest, guy I got it from worked as a radio engineer), and opened it up to see if there is anything interesting in there. Found a couple what look and sound like attenuators to me. Both are made by The Daven Company, the first's marking indicate its 600/600 ohm, 2db/step, while the second one indicate its 600/600 .1db/step. I can't find much info based on the model name on a quick Google search, but I did run into some people posting good things about Daven attenuators. Anyone here have any more info for me?

I've attached a couple pics of the parts to help. There wasn't really anything else of interest in the case, a couple selector switches and that kind of a deal.
Attached Images
File Type: jpg ohv604.jpg (126.6 KB, 179 views)
File Type: jpg 11bng2s.jpg (159.5 KB, 170 views)
File Type: jpg 2e515x5.jpg (96.0 KB, 168 views)
File Type: jpg 10dhyk5.jpg (106.4 KB, 166 views)

Last edited by elizard; 10th January 2012 at 01:23 AM.
  Reply With Quote
Old 10th January 2012, 01:29 AM   #2
elizard is offline elizard  Canada
diyAudio Member
 
Join Date: Mar 2003
Location: Winnipeg, MB
Send a message via MSN to elizard
I also managed to snag a power supply from him, which included a nice schematic drawn some 30-40 years ago when he built it, though the only spec I managed to grab was the output voltages (300V + 6.3V), no indication of current sadly.
Attached Images
File Type: jpg 16kdw6t.jpg (109.4 KB, 161 views)
  Reply With Quote
Old 10th January 2012, 02:45 AM   #3
expert in tautology
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
There is a tag on it, what does it say?

I can't read the labels on the black dials, ur pic is too blurry... looks to me like a custom test set of some sort...

The attenuators can be redone inside for use in a stereo as level controls, btw.

_-_-bear
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
  Reply With Quote
Old 10th January 2012, 03:02 AM   #4
elizard is offline elizard  Canada
diyAudio Member
 
Join Date: Mar 2003
Location: Winnipeg, MB
Send a message via MSN to elizard
First attenuator:

Type: BH-520-G
Network: bal "H"
600/600 1db/step
40db total

Second:
Type: BH-525-G
Network: bal "H"
600/600 .1dn/step
2db total

As for using them as level controls instead of pots, that was my idea for them, though I'm not sure how I'd need to modify them. Any tips or links to reading material is appreciated. I'll have to spend more time researching it tomorrow, now its time for bed.

Last edited by elizard; 10th January 2012 at 03:09 AM.
  Reply With Quote
Old 10th January 2012, 03:08 AM   #5
elizard is offline elizard  Canada
diyAudio Member
 
Join Date: Mar 2003
Location: Winnipeg, MB
Send a message via MSN to elizard
And clearer pictures:
Attached Images
File Type: jpg 4ke5x2.jpg (93.3 KB, 40 views)
File Type: jpg io12d2.jpg (107.0 KB, 29 views)
File Type: jpg ouwlr4.jpg (108.7 KB, 22 views)
  Reply With Quote
Old 10th January 2012, 09:07 AM   #6
expert in tautology
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
Looks likes a manufacturer's tag under the handle on the front??

PM me on the attenuators...

_-_-bear
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
  Reply With Quote
Old 10th January 2012, 01:32 PM   #7
elizard is offline elizard  Canada
diyAudio Member
 
Join Date: Mar 2003
Location: Winnipeg, MB
Send a message via MSN to elizard
Yep, I'll post a pic later .. here's the info from the tag:

Automatic Electrics
TEST SET
S.F. CIRCUIT TYPE 24
CKT.H-85833-1
PC.NO.H-883354-1

Thanks for the help
  Reply With Quote
Old 11th January 2012, 08:47 AM   #8
diyAudio Member
 
dchisholm's Avatar
 
Join Date: Mar 2011
Location: St Louis, Mo
It looks like you have a piece of telephone central office test gear. "Automatic Electric" manufactured PBX and central office equipment for smaller, non-Bell System phone companies. (If memory serves, Automatic Electric was a direct descendent of the company founded by Mr Strowger to manufacture the automated telephone exchange switch he invented about 1900.) Judging by visual aesthetics, I'd guess that your test set is 1960's or 1970's vintage.

The Daven attenuators were legendary for their long life and noise-free operation. In a high-operation application like a broadcast console they were expected to last almost forever if the tech staff gave them a shot of contact cleaner every year or so. (Hence, the removable can on the back side.) If a console was ever scrapped or damaged beyond repair it wasn't unusual to salvage the attenuators.

Your attenuators are labeled as "Balanced H-pad" networks. You can seed a search engine to find references for this circuit; it's essentially the balanced version of the constant impedance T-pad. Since the 0.1 dB/step unit is in the same test set as a 2 dB/step unit, I'd wager that the 2 dB/step unit is a high-accuracy model. I can't tell for sure from the photos - are they dual-section (stereo) units?

In the "good old days" (formerly known as "these trying times"), telco and pro-audio line-level interfaces were usually 600 ohms for both inputs and outputs, and attenuators such as yours interposed between sources and loads. This allowed (among other things) output drivers to operate at a constant level into a known resistive load, and inputs were driven from a known, constant, source impedance. This arrangement had advantages in the areas of predictability, noise, and distortion performance. The main disadvantage is that half of the available voltage swing was dropped across the internal impedance. Attenuators were also used (as in your test set) as accurate measuring instruments. It was easier to build resistive attenuators with the desired initial accuracy, repeatability, and low drift than to design and build a precision metering circuit (and keep it calibrated).

Today most equipment has low output impedance, high input impedance; simple potentiometers are used to set levels and the gear is designed to tolerate a fairly wide range of source and load impedances. In light of that technological evolution your attenuators may qualify as historical artifacts. However, they are still high-performance units and it seems a waste to destroy the accuracy by replacing the resistors. The 0.1 dB/step in particular is not nearly as common as 1 dB- or 2 dB/step units. With a little research you may discover that their value as used test gear is enough for you to purchase a high-quality, audio step-pot that is already well suited for your intended application.

If you have access to the necessary resistor values in tight-tolerances (better than 1%) then there is a case for rebuilding them as, say, attenuators with 1K, 2.5K, or 10K characteristic impedances. To use them as-is you could place them between impedance-matching transformers from, e.g., Jensen or Lundahl. You could also design a 2-resistor impedance-matching L-pad for the input. This would raise the input impedance to a level (say, a few kilohms) that your driver stage can live with - but will also reduce the signal level.

Dale
  Reply With Quote
Old 11th January 2012, 02:15 PM   #9
elizard is offline elizard  Canada
diyAudio Member
 
Join Date: Mar 2003
Location: Winnipeg, MB
Send a message via MSN to elizard
Quote:
Originally Posted by dchisholm View Post
Your attenuators are labeled as "Balanced H-pad" networks. You can seed a search engine to find references for this circuit; it's essentially the balanced version of the constant impedance T-pad. Since the 0.1 dB/step unit is in the same test set as a 2 dB/step unit, I'd wager that the 2 dB/step unit is a high-accuracy model. I can't tell for sure from the photos - are they dual-section (stereo) units?
They are stereo units, yes.

Quote:
Originally Posted by dchisholm View Post
Today most equipment has low output impedance, high input impedance; simple potentiometers are used to set levels and the gear is designed to tolerate a fairly wide range of source and load impedances. In light of that technological evolution your attenuators may qualify as historical artifacts. However, they are still high-performance units and it seems a waste to destroy the accuracy by replacing the resistors. The 0.1 dB/step in particular is not nearly as common as 1 dB- or 2 dB/step units. With a little research you may discover that their value as used test gear is enough for you to purchase a high-quality, audio step-pot that is already well suited for your intended application.
Apart from ebay, do you have any suggestions as to where I may find an interested party in purchasing the attenuators? I was planning on rebuilding them, but if they have a significant value, they would help fund my F5 build.

Thanks for the help.
  Reply With Quote
Old 11th January 2012, 02:31 PM   #10
diyAudio Member
 
analog_sa's Avatar
 
Join Date: Aug 2002
Location: Sofia
The attenuators may fetch five bucks a piece or thereabouts. At least that's what i paid for mine.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
parts identification imET Everything Else 7 4th September 2010 07:59 PM
2 600 ohm daven attenuator nhuwar Swap Meet 1 24th August 2009 01:53 AM
Daven Question nhuwar Tubes / Valves 0 15th February 2009 11:40 PM
Company name wanted !? metal Multi-Way 6 3rd January 2007 06:54 PM
PARTS PARTS PARTS!!! Infocus Powerview 820, triplet, ballast, light, power supply!!! marioinla Swap Meet 1 31st August 2004 04:22 PM


New To Site? Need Help?

All times are GMT. The time now is 06:49 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2