Contact us / F A Q

To contact Chris regarding scoring and production work please visit christianruggiero.com.

******

Regarding the various audio-technical-articles on this website: I cannot offer gratis technical support at this time.  For other inquiries you can reach me at Chris at PreservationSound dot com.

*******

If you have some old audio item and want to know ‘what is it worth?,’  your best bet is to examine the ‘sold listings’ on eBay for similar items. That’s where I start,,,

*******

If you want advice about how to do develop the skills necessary to scratch-build and repair tube-type audio equipment, I can’t offer any to you.  There are a great many people for whom this is just not-for.  It’s a frustrating, difficult, dangerous, and fairly expensive endeavor to train one’s self in.   On the other hand, you might take two years to get-to where I’ve gotten to in fifteen years!  I just don’t know, so I am not going to offer any advice on this subject.

That being said, I can share with you how I developed the skills that I have.  I was in a rock band that toured a lot.  We used big vintage Fender tube amps.  They would sometimes need servicing, and at the time (circa 2003) the tube amp repairmen we could find in NYC were expensive and/or unpleasant and/or incompetent.  We had a few bad experiences, so one day in Nashville I picked up an on-sale copy of Aspen Pittman’s “The Tube Amp Book” at Valley Arts for $15.  I figured it was worth a shot seeing if I could fix my own gear.  I read the book over and over again that tour.  When we got back, I bought a basket-case Tweed Gibson 50 watt amp on eBay for $120.  I had basic soldering skills (I had built a few science fair things and a PAIA theremin kit as a kid) but that was it.  I read a few blogs and it seemed like the Fender 5F2A Princeton was a useful amp that was a good ‘beginners’ project.  So I decided to use the chassis and as many other parts as I could salvage from the Gibson and make a 5F2A clone.  It took about a month, and it worked but it sounded fkkn awful. So I did it again, this time with a fresh Hammond aluminum box.  This one took about A YEAR.  It had a parasitic oscillation problem that literally took a year to figure out.  But once I squared it, it sounded pretty good!  So I built another one.  And another.  Now it was getting easier.

I moved on mic preamps.  I started with the RCA BA2C because it seemed simple.  I think I got lucky and I figured that out pretty quickly.  So then I started trying anything I could – Tremoluxes, phono pres, power amps, more mic pres, compressors, ETC, ETC, basically whatever I could make that did not require fancy custom-would transformers or inductors.  There were many successes and some very frustrating failures.   And all along, as I was making all this stuff (probably around 200 scratch-built pieces at this point), I was buying any and every cheap (under $30) old tube amp I could find and either fixing it up or parting it out if it was too effed.  Once I fought my way through a few hundred old chassis of every stripe, I had been exposed to pretty much every layout, wiring, mechanical, and related non-schematic quirk that actual trained designers used in the original tube audio era.

I bought decent tools, I use a temp-controlled Weller soldering iron, I have basic multimeters and a $300 scope and some decent basic audio test gear.  I use a solder-fume extractor and safety glasses whenever I work.  I buy most parts from Mouser, Antique Electronic Supply, EDCOR, and Jensen,  and most tools from MCM electronics.   I try not to read too much commentary online because the internet is simply not a reliable source of information; instead I bought hundreds, maybe thousands of old issues of Television and Radio Repair, AUDIO magazine, the AES Journal, etc., etc.  Primary-source documents, essentially.  The internet is, however, useful as a source of schematics, and I have downloaded and/or screen-captured just about every single tube-amp schematic I have ever seen – many thousands – I and I keep them all indexed on my macbook and always take the time to study every one of them looking for new (old) ways to do things.  I don’t fully understand all of them yet, but maybe I’ll get there someday.

*******

Thanks and have a great day.

View Comments

    • Thanks Paul i just wanted the origin of my pilot i bought it with my first income tax check and wanted to know what it might be worth. Here are some numbers i took off the back top row i believe o40432. Next row 167730.......... next row apw90f301 cat #0951

  • Had a reel to reel in high school/ recorded regularly off the TV( American Bandstand). Hooked up wires to the tv speakers and jacked this into the tape recorder. Still have the tapes/ brought the tape recorder to parties as a music source. I guess I was one of the first DJs.

    • Hi! I picked up a Magnecord 1048 recently and wondered if anyone was willing to share an owner’s manual with me? I have a tube tech guru who needs it in order to service it and bring it back to as close to original condition as he can. Any help? Thanks in advance! -Todd

  • Hi,
    I've discovered on a fly market a "Brush Sound Mirror" reel to reel, probably a BK401.
    It seems to be in good state. I want to restore it as carefully as possible.
    My work should be more easy if I had some technical information about the machine.
    Do you think that I could find the user manual, service manual, schematics, etc... ?
    Where ?
    Thank you very much if you could help me to find sources of information.
    Freddy

    • Hi Jamie. thanks for writing. as i explained in the article, the unit is simply a combination of the BA2 and the OP6. I don't have a complete schematic drawn; but you really don't need one... just join the input stage of the the BA2 (up to the output wiper of the volume pot) to the OP6 (from the grid of stage 2 on out). be sure to add a 1M resistor from the grid of stage 2 to ground; isolate this from the volume pot with a 1K resisitor. You can use the power supply from either unit;you should also use DC filament supply. Good luck. the piece sounds really awesome; it's worth the effort.

      OH BTW also... since it is a 90DB gain preamp... there is SOME hum at high levels... so would recommend using the Jensen triple-sheilded inoput transformer rather than the basic 115 transfo that i used.

      c.

  • how many IPS does the Fostex A-8 (8track) record I have tapes i want to digitze and all studios are asking me what speed it was recorded at.

  • Have an interesting horn, not sure if it came from gramophone (cast), or logging horn. Thank You I will send pics if you give the go ahead

  • Hi,

    I just came across your terrific site while trying to find some information about an old microphone. I have an Electro-Voice model 664 serial number 181415. I'm trying to buy a desk stand for it. Apparently something called the stud size changed in 1968. If I have the pre-1968 version then I can use a 418 base. Otherwise, I need the 419. These are not cheap. They're running between 75 and 150 dollars on eBay, so I want to make the correct choice. Anyway, thanks in advance.

    Shawn Rosvold

    • Hi shawn. I don't have an idnex of EV serial numbers. Can anyone else help shawn out? I can tell you that in my life i have only see 3 different sizes of professional-mic thread-sizes, and couplers to adapt them all are still avail cheaply; try BSW, marketek, full compass, etc... good luck...

  • I can't believe a site like this exists! Older gear has fascinated me ever since I found a Foxx wah and Fender Bandmaster amp in a barn about 25 years ago. Old gear takes me to another era. Thank you so much for this site!!

  • I have a pair of Bozak ls330a speakers that have a 1 and 2 on the back for speaker hookup. My question is which one would go to the + or - on the receiver or amp

    • Mark: I have used the following technique in the past. You will need to visually see the actual speaker cone in order to do this. Attempt at your own risk.
      SOURCE: http://www.thegearpage.net/board/archive/index.php/t-663468.html

      "An old trick is to take a 9V battery and connect it to the guitar speaker (9V won't hurt the speaker if connected momentarily-----connect each pole "+" and "-" to the speaker connections---i have a 9V speaker clip with two alligator clips made up for this purpose) --- the speaker will move In or Out---- the speaker connection that is connected to the "+" 9V battery pole, when the speaker moves Out (away from the magnet)--- this is the Pos speaker connection.
      The same 9V battery trick can also be used to check if multipule speaker cabs have all their speakers connected "in phase"--- connect speaker cable to cab and then connect 9V to the Tip and Sleeve connectors of the speaker cable plug----see if all speakers are moving in the same direction-----then put the back panel of the 4x12 cab on and jam out.......................gldtp99"

      • I have used this idea with a 1.5 volt "D" cell & "C" cell also. If you cannot get access to the speaker cone itself, try taping a piece of tissue paper of some kind onto the front of the speaker grill. Then momentarily touch the positive side of the battery to the wire. You may have to do this several times to be able to see the tissue paper move, however when it moves "out" a little, you will see it, and there you have the + connection! Good luck!

Leave a Comment