<<previous : next >>
Contact

DIY Bias Probe

From kee–(at)–den.com Sun Jan 28 18:24:35 CST 1996
From: kee–(at)–den.com (R.G. Keen)
Newsgroups: alt.guitar.amps
Subject: Re: Does Anyone Own the Bias Probe?
Date: 28 Jan 1996 19:05:48 GMT

Brian C. DenUyl – Staff (denuyl–(at)–iver.it.gvsu.edu) wrote:
: I was wondering if any of you use the Bias Probe and how it works.
: Can you get the same results by soldering a 1 ohm resistor between the
: cathode and ground on the output tubes and measuring this with a meter
: while adjusting the bias? How is the manual that comes with the Bias
: Probe? Just out of curiosity, what does the manual recommend for the
: Nominal mV and Maximum mV rating for a Fender Deluxe Reverb? Thanks,

The “Bias Probe” is a commercialization of the old socket extender trick.

This is, by the way, a great use for those old burned out octal tubes.

You can easily make your own by getting a pair of octal sockets and the
old bases from some burned out tubes. Unsolder the bases and slip them
off the old tube. Stack the socket about 1″ or so above the octal base on
some stiff wires, soldering the wires into the tube base, then solder the
wires on to the matching pins of the socket. Put a 1 ohm resistor (or whatever
your favorite measurement value is) instead of wire in the cathode pin
position between the two. Make two.

You probably ought to solder a pair of wires at each end of the resistor
so you don’t get fried trying to stick voltmeter leads in there when
you’re using the thing.

To use this, remove the output tubes from the amp, stick the socket
extenders in the sockets, and stick the tubes into the sockets on the top
of the extenders. Now you can fire up the amp and measure cathode current
directly as teh voltage across the resistors.

R.G.

From kee–(at)–ustin.ibm.com Wed Jan 31 21:10:27 CST 1996
From: kee–(at)–ustin.ibm.com ()
Newsgroups: alt.guitar.amps
Subject: Re: “Biasing Devices”
Date: 31 Jan 1996 15:18:43 GMT
Distribution: world
Originator: kee–(at)–een.austin.ibm.com

In article <310D8A92.253--(at)--nsinc.com>, Bruce J writes:
> I was wondering about “easy” bias sockets sold by a couple of mfgs.
> Do/CAN they work? (I get the feeling there may be some strong opinions
> about this.) I think one I saw was by Audio Glassic and it is a socket
> you just put into the tube base and make biasing easy. For those of us
> who will admit to having more amps than we have tube electronics skill,
> it would be nice to have an easy way to bias our own amps. I’d really
> like some opinions or warnings – but esp. by anyone who has used one of
> these.
>
You can make your own. These devices usually are an octal base on bottom
to plug into the amp’s tube socket, and an octal socket above. All pins are
usually wired 1 to 1, 2 to 2, and so on with heavy copper wire, except that
the cathode lead has a resistance of 1 to 10 ohms in it and leads coming
out to measure the voltage drop across the resistors.

You can unsolder the octal socket from a burned out tube. If you want to make
a dedicated meter, you can get digital panel meters with a +/- 199 millivolt
range for under $20 these days, so you could actuall put one of these
on each socket if you make a pair of socket. One ohm is 1 millivolt per
miliamp, 10 ohms is ten millivolts per milliamp.

Warnings? Be very careful how you wire them and be sure to insulate them
carefully once they are made so you can’t get hold of the high voltage
leads – which may be any of them.

R.G.

Yamaha Power Amp Mx600-U Parts Amp Power Switch Board
$19.95
End Date: Saturday Feb-17-2018 17:07:00 PST
Buy It Now for only: $19.95
Buy It Now | Add to watch list
Yamaha Power Amp Mx600-U Parts Transformer
$18.95
End Date: Saturday Feb-17-2018 17:07:23 PST
Buy It Now for only: $18.95
Buy It Now | Add to watch list
EQ Piezo Pickup Pre-Amp Great Tone for Folk Acoustic Guitar Parts Instrument
$7.54
End Date: Saturday Feb-17-2018 17:31:36 PST
Buy It Now for only: $7.54
Buy It Now | Add to watch list
Altec 1592B 5-Channel Mixer Amplifier For Parts or Repair 1592 B Amp #30838
$249.00
End Date: Saturday Feb-17-2018 17:55:16 PST
Buy It Now for only: $249.00
Buy It Now | Add to watch list
3pcs Turret Terminal Tag Strip 3Lugs Board Audio Guitar Tube Amplifier Parts
$8.55
End Date: Saturday Feb-17-2018 19:06:54 PST
Buy It Now for only: $8.55
Buy It Now | Add to watch list
1pc Sliver Tube Guard Protector Cover For EL84 6BQ5 6P14 Audio Amp Parts
$12.00
End Date: Saturday Feb-17-2018 19:27:18 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
Kenwood KA 6004 Vintage Amp Amplifier - For Parts, Not working
$88.00
End Date: Saturday Feb-17-2018 19:49:21 PST
Buy It Now for only: $88.00
Buy It Now | Add to watch list
Build Cigar Box Guitar DVD vintage 3 & 4 string great for your parts kit or amp
$28.50
End Date: Saturday Feb-17-2018 20:12:05 PST
Buy It Now for only: $28.50
Buy It Now | Add to watch list
Realistic MPA-95 100 Watt P.A. Mixer / Amp 4 XLR Mic Channels Works **PARTS**
$45.00
End Date: Saturday Feb-17-2018 20:17:29 PST
Buy It Now for only: $45.00
Buy It Now | Add to watch list
AMERICAN AUDIO POWER AMP APX POWER PRO AMP SECTION, BUCKET. FOR REPAIR OR PARTS
$13.95
End Date: Saturday Feb-17-2018 20:38:09 PST
Buy It Now for only: $13.95
Buy It Now | Add to watch list
Kenwood solid state amplifier ka 2002. purchase as shown for repair or parts.
$30.00 (0 Bids)
End Date: Saturday Feb-17-2018 21:54:37 PST
Buy It Now for only: $40.00
Buy It Now | Bid now | Add to watch list
30pc 8PIN Vacuum TUBE SOCKET SAVER FOR KT88 6550 EL34B AUDIO tube amp DIY parts
$36.48
End Date: Saturday Feb-17-2018 22:03:42 PST
Buy It Now for only: $36.48
Buy It Now | Add to watch list
GD-PARTS KT88 Push Pull Integrated Tube Amplifier 35W 60W Hifi Audio Tube AMPx1
$874.00
End Date: Saturday Feb-17-2018 22:09:51 PST
Buy It Now for only: $874.00
Buy It Now | Add to watch list
JBL UREI 6260 2-Channel Power Amplifier *For Parts/Repair*
$199.99
End Date: Saturday Feb-17-2018 22:36:24 PST
Buy It Now for only: $199.99
Buy It Now | Add to watch list
2pcs Mini Ceramic 7pin Tube Socket 2A7 6A7 PCB valve Base Amp Parts
$14.40
End Date: Sunday Feb-18-2018 1:35:08 PST
Buy It Now for only: $14.40
Buy It Now | Add to watch list
Pickup Violin Parts for Musical Instruments Dragonpad Violin amp or PA US
$7.29
End Date: Sunday Feb-18-2018 2:50:29 PST
Buy It Now for only: $7.29
Buy It Now | Add to watch list
MATCHED SET PAIR 2 SYLVANIA 6L6WGB 6L6GB TESTASNEW Stereo Amp Vacuum Tubes Parts
$49.95
End Date: Sunday Feb-18-2018 5:04:39 PST
Buy It Now for only: $49.95
Buy It Now | Add to watch list
4pc 9PIN PCB ceramics Vacuum TUBE SOCKET FOR 12AU7 12AX7B AUDIO tube amp parts
$4.49
End Date: Sunday Feb-18-2018 5:46:15 PST
Buy It Now for only: $4.49
Buy It Now | Add to watch list
Tech 21 Trademark 10, Guitar Amplifier Parts, Equalizer, Spring Reverb, Vintage
$175.00
End Date: Sunday Feb-18-2018 5:53:52 PST
Buy It Now for only: $175.00
Buy It Now | Add to watch list
MATCHED SET TRIO 3 SYLVANIA 6L6WGB 6L6GB TESTASNEW Stereo Amp Vacuum Tubes Parts
$74.00
End Date: Sunday Feb-18-2018 6:08:03 PST
Buy It Now for only: $74.00
Buy It Now | Add to watch list
MATCHED PAIR 2 RCA JAN 5751 12AX7A TESTNEARNEW Vtg Guitar Amp Vacuum Tubes Parts
$69.00
End Date: Sunday Feb-18-2018 6:50:22 PST
Buy It Now for only: $69.00
Buy It Now | Add to watch list
Cigar Box Guitar Parts: 25pc. 1/4-inch Mono Guitar & Amplifier Audio Jacks
$29.99
End Date: Sunday Feb-18-2018 6:55:53 PST
Buy It Now for only: $29.99
Buy It Now | Add to watch list
vintage nos. fender pilot light guitar amp parts
$9.99 (0 Bids)
End Date: Sunday Feb-18-2018 6:59:49 PST
Bid now | Add to watch list
JBL 6233 Dual 300 Watt Power Amplifier - Complete unit For Parts Not Working
$199.00
End Date: Sunday Feb-18-2018 7:17:03 PST
Buy It Now for only: $199.00
Buy It Now | Add to watch list
4pc Vacuum TUBE SOCKET SHIELD FOR SHUGUANG KT88 AUDIO tube amp DIY parts
$6.78
End Date: Sunday Feb-18-2018 7:25:38 PST
Buy It Now for only: $6.78
Buy It Now | Add to watch list
4pc 9PIN shell bakelite Vacuum TUBE SOCKET For 12AX7 12AU7 AUDIO tube amp parts
$4.75
End Date: Sunday Feb-18-2018 7:43:44 PST
Buy It Now for only: $4.75
Buy It Now | Add to watch list
AKAI AM-2200 INTEGRATED AMPLIFIER SERVICE MANUAL WITH PARTS LIST ORIGINAL
$18.52
End Date: Sunday Feb-18-2018 7:43:49 PST
Buy It Now for only: $18.52
Buy It Now | Add to watch list
Alesis Model RA150 Stereo Amplifier-Powers Up No Output-Parts or Repair-m1072
$64.99
End Date: Sunday Feb-18-2018 7:47:27 PST
Buy It Now for only: $64.99
Buy It Now | Add to watch list
#MISC-2001 - 1980s FENDER BASSMAN 20 AMPLIFIER - PARTS LIST & SPECIFICATIONS
$12.00
End Date: Sunday Feb-18-2018 8:04:34 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
#MISC-2002 - 1980s FENDER BASSMAN 70 AMPLIFIER - PARTS LIST & SPECIFICATIONS
$12.00
End Date: Sunday Feb-18-2018 8:04:41 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
#MISC-2004 - 1980s FENDER SIDEKICK AMPLIFIER - PARTS LIST & SPECIFICATIONS
$12.00
End Date: Sunday Feb-18-2018 8:04:56 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
#MISC-2005 - 1980s FENDER CHAMP AMPLIFIER - PARTS LIST & SPECIFICATIONS
$12.00
End Date: Sunday Feb-18-2018 8:05:03 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
#MISC-2010 - 1980s FENDER DELUXE REVERB II AMPLIFIER PARTS LIST
$12.00
End Date: Sunday Feb-18-2018 8:05:38 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
#MISC-2012 - 1980s FENDER PRINCETON REVERB AMPLIFIER PARTS LIST
$12.00
End Date: Sunday Feb-18-2018 8:05:51 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
MISC-2013 1980s FENDER PRINCETON REVERB II AMPLIFIER PARTS LIST
$12.00
End Date: Sunday Feb-18-2018 8:05:58 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
Crown CTs 4200 Four-Channel Power Amplifier GCTS4200A **For Parts
$49.95 (0 Bids)
End Date: Sunday Feb-18-2018 8:07:21 PST
Bid now | Add to watch list
PEAVEY PL-800-EQ  Active Crossover Network 800 Hz N.O.S. STEREO amp guitar PARTS
$12.92 (0 Bids)
End Date: Sunday Feb-18-2018 8:33:54 PST
Bid now | Add to watch list
Bridges &Amp;Amp; Bridge Parts Floyd Rose Licensed Black Guitar Tremolo System,
$34.92
End Date: Sunday Feb-18-2018 11:35:00 PST
Buy It Now for only: $34.92
Buy It Now | Add to watch list
5pc 7Pin Red Bakelite Vacuum Tube sockets base HIFI audio amplifier radio parts
$15.48
End Date: Sunday Feb-18-2018 12:36:35 PST
Buy It Now for only: $15.48
Buy It Now | Add to watch list
MCINTOSH MI-75 MONO TUBE POWER AMP SERIAL #1 FIRST ONE SOLD. for parts or repair
$4,500.00 (0 Bids)
End Date: Sunday Feb-18-2018 12:36:42 PST
Bid now | Add to watch list
Vintage Sony TA-2650 Integrated Stereo Amplifier; Japan; Parts & Repairs (F)
$31.00 (4 Bids)
End Date: Sunday Feb-18-2018 12:48:23 PST
Bid now | Add to watch list
5pc 8Pin Gold Ceramic Vacuum Tube sockets base Fr 6L6 EL34 KT88 audio amp parts
$29.78
End Date: Sunday Feb-18-2018 12:52:46 PST
Buy It Now for only: $29.78
Buy It Now | Add to watch list
MISC-2019 1980s FENDER MA4 MIXER PRE AMP PARTS LIST & SPECIFICATIONS
$12.00
End Date: Sunday Feb-18-2018 12:53:56 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
MISC-2020 1980s FENDER MA4 MIXER POWER AMP PARTS LIST & SPECIFICATIONS
$12.00
End Date: Sunday Feb-18-2018 12:54:04 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
MISC-2021 1980s FENDER MA-6 AMP/MIXER PARTS LIST & SPECIFICATIONS
$12.00
End Date: Sunday Feb-18-2018 12:54:12 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
MISC-2022 1980s FENDER MA-8-S AMP/MIXER PARTS LIST & SPECIFICATIONS
$12.00
End Date: Sunday Feb-18-2018 12:54:19 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
MISC-2024 1980s FENDER BASSMAN COMPACT AMPLIFIER PARTS LIST & SPECIFICATIONS
$12.00
End Date: Sunday Feb-18-2018 12:54:36 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
MISC-2025 1980s FENDER BASSMAN COMPACT AMP PARTS LIST & SPECIFICATIONS
$12.00
End Date: Sunday Feb-18-2018 12:54:44 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
MISC-2026 1980s FENDER SLIMLINE AMP PARTS LIST & SPECIFICATIONS
$12.00
End Date: Sunday Feb-18-2018 12:54:51 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
MISC-2027 1980s FENDER 300W SLIMLINE AMP PARTS LIST & SPECIFICATIONS
$12.00
End Date: Sunday Feb-18-2018 12:54:59 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
MISC-2028 1980s FENDER 300W SLIMLINE BASS AMP PARTS LIST & SPECIFICATIONS
$12.00
End Date: Sunday Feb-18-2018 12:55:07 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
TEAC/TASCAM REEL REEL PARTS--- REC/AMP PCB BOARD PT # PCB 111
$65.00
End Date: Sunday Feb-18-2018 13:10:50 PST
Buy It Now for only: $65.00
Buy It Now | Add to watch list
Carver PM 1200 Amplifier - WORKS - and Bonus additional non-working part
$78.00 (12 Bids)
End Date: Sunday Feb-18-2018 13:15:09 PST
Bid now | Add to watch list
Kenwood KA-2002 Chassis Screws & Parts. Parting Out KA-2002 Amplifier.
$9.99
End Date: Sunday Feb-18-2018 13:15:48 PST
Buy It Now for only: $9.99
Buy It Now | Add to watch list
MISC-2033 1980s FENDER HARVARD REVERB AMPLIFIER PARTS LIST & SPECIFICATIONS
$12.00
End Date: Sunday Feb-18-2018 13:16:01 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
MISC-2035 1980s FENDER 75 HEAD TOP AMPLIFIER PARTS LIST & SPECIFICATIONS
$12.00
End Date: Sunday Feb-18-2018 13:16:17 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
MISC-2038 1980s FENDER 1-12 HF ENCLOSURE AMPLIFIER PARTS LIST & SPECIFICATIONS
$12.00
End Date: Sunday Feb-18-2018 13:16:43 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
MISC-2043 1980s FENDER SUPER TWIN REVERB AMPLIFIER PARTS LIST & SPECIFICATIONS
$12.00
End Date: Sunday Feb-18-2018 13:17:21 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
Kenwood KA-2500 Receiver Chassis Screws & Parts. Parting Out KA-2500 Amplifier.
$9.99
End Date: Sunday Feb-18-2018 13:21:38 PST
Buy It Now for only: $9.99
Buy It Now | Add to watch list
Aiwa AV-D58 Stereo AV Receiver/Amp Super T-Bass-Working-As Is for Parts/Repair
$19.00 (0 Bids)
End Date: Sunday Feb-18-2018 13:54:59 PST
Bid now | Add to watch list
5pc 8Pin Red Gold Bakelite Vacuum Tube sockets Fr 6L6 EL34 KT88 audio amp parts
$11.15
End Date: Sunday Feb-18-2018 13:56:52 PST
Buy It Now for only: $11.15
Buy It Now | Add to watch list
Guitar Parts Acoustic Pickup Pre-Wired Piezo Amplifier Jack ZH
$2.07
End Date: Sunday Feb-18-2018 14:07:36 PST
Buy It Now for only: $2.07
Buy It Now | Add to watch list
VINTAGE AIMS mini vocal sound system head PA AMPLIFIER AMP as-is parts or repair
$199.99
End Date: Sunday Feb-18-2018 14:07:50 PST
Buy It Now for only: $199.99
Buy It Now | Add to watch list
Pr. 12" Paper Speaker Cones -- Recone Parts -- 7122033AMP
$15.95
End Date: Sunday Feb-18-2018 14:10:11 PST
Buy It Now for only: $15.95
Buy It Now | Add to watch list
Vintage Tube Amp Kit Open Frame Mono For parts or repair 9x7 Unknown MFG
$34.00 (1 Bid)
End Date: Sunday Feb-18-2018 14:12:01 PST
Bid now | Add to watch list
Numark DM1002X Pre-amp Mixer - Untested; Parts & Repair
$9.99 (0 Bids)
End Date: Sunday Feb-18-2018 14:16:05 PST
Bid now | Add to watch list
Mackie SRM 450 Powered Speaker Amp Module Use for Parts or Try to Fix SRM450 PCB
$69.00
End Date: Sunday Feb-18-2018 14:23:55 PST
Buy It Now for only: $69.00
Buy It Now | Add to watch list
Mackie SRM 450 Powered Speaker No Amp Module Use for Parts or Try to Fix
$79.00
End Date: Sunday Feb-18-2018 14:27:28 PST
Buy It Now for only: $79.00
Buy It Now | Add to watch list
LOCAL ONLY AS IS for parts ROGUE Amplifier 2 x 12" Cabinet Only w/burnt chassis
$35.00
End Date: Sunday Feb-18-2018 14:30:09 PST
Buy It Now for only: $35.00
Buy It Now | Add to watch list
klangfilm tube EL12, AZ12, EF12 power amp, pair, unworked, for parts or repair
$390.00
End Date: Sunday Feb-18-2018 14:39:37 PST
Buy It Now for only: $390.00
Buy It Now | Add to watch list
TOA A-906A Amplifier - As Is, Non-Working, For Parts
$25.00
End Date: Sunday Feb-18-2018 14:40:09 PST
Buy It Now for only: $25.00
Buy It Now | Add to watch list
RCA 6B10 PAIR 2 OEM Stereo TV Ham Radio Amp Tubes Replacement Parts NOS NIB
$7.50
End Date: Sunday Feb-18-2018 14:41:52 PST
Buy It Now for only: $7.50
Buy It Now | Add to watch list
MISC-2045 1980s FENDER 30 AMPLIFIER PARTS LIST & SPECIFICATIONS
$12.00
End Date: Sunday Feb-18-2018 14:47:28 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
MISC-2047 1980s FENDER TWIN REVERB AMPLIFIER PARTS LIST & SPECIFICATIONS
$12.00
End Date: Sunday Feb-18-2018 14:47:42 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
VINTAGE MITSUBISHI DA-R25 STEREO RECEIVER AMPLIFIER FOR parts
$49.95
End Date: Sunday Feb-18-2018 14:47:54 PST
Buy It Now for only: $49.95
Buy It Now | Add to watch list
MISC-2049 1980s FENDER VIBROLUX REVERB AMPLIFIER PARTS LIST & SPECIFICATIONS
$12.00
End Date: Sunday Feb-18-2018 14:47:56 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
MISC-2050 1980s FENDER VIBROSONIC REVERB AMPLIFIER PARTS LIST & SPECIFICATIONS
$12.00
End Date: Sunday Feb-18-2018 14:48:04 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
MISC-2054 1980s FENDER BANDMASTER REVERB AMPLIFIER PARTS LIST & SPECIFICATIONS
$12.00
End Date: Sunday Feb-18-2018 14:48:31 PST
Buy It Now for only: $12.00
Buy It Now | Add to watch list
RCA 6AL11 PAIR 2 OEM Stereo TV Ham Radio Amp Tubes Replacement Parts NOS NIB
$9.95
End Date: Sunday Feb-18-2018 14:48:47 PST
Buy It Now for only: $9.95
Buy It Now | Add to watch list
Fender Frontman 15R Guitar Amplifier PARTS/REPAIR
$8.00 (0 Bids)
End Date: Sunday Feb-18-2018 15:08:14 PST
Bid now | Add to watch list
5pc 9pin Ceramic vacuum tube sockets valve 12AX7 12AU7 6P1 EL84 Audio amp parts
$8.74
End Date: Sunday Feb-18-2018 15:16:54 PST
Buy It Now for only: $8.74
Buy It Now | Add to watch list