up to date as of 1/2021
OK, time to let some things go so they can be put back into use. Input, interstage, output, repeat coils, and power. Some singles, some pairs. In this issue:
RCA BA-3 program amp input and output transformer set
(2) RCA MI-38482 nine pin plug-in transformers (McMartin MT-4) tube inputs
Kenyon T-26 600:600
Gates console panel with 3 transformers
Presto PPP 6L6/807 tube record lathe power amp output transformer and choke
Thordarson PP 6V6 to 500 ohm output transformer pair, good for Sta-Level, etc
Tube output transformer for four 6L6
Pair of IOaudio input transformers for Pultec
RCA potted power transformers 70VCT 800mA
ADC HUM-1 video humbuckers
RCA BA-3 program amp input and UTC output transformer set
Indeed. Both test well. The BA-3 is a killer single ended high gain preamp with high max output level. The UTC output is NOS, very difficult to find a high level single ended output like this with good low frequency response. The input is in great shape.
Input is 150/600 to grid.
Output is for single ended 6V6 or 6L6 (RCA did both with this) to 600/150/15/7.5/5 at +30dBm with less than 1% THD 30-15K as used in a BA-3. Lots of BA-3’s in use for vintage audio speaker listening, especially with efficient horn systems.
$600 plus shipping/insurance on 9 lbs.
(2) RCA MI-38482 nine pin plug-in transformers
Accessory transformer for the 1970’s SA-115 transistor general use amplifier, which appears to be a rebadged McMartin unit. A good guess would be these are rebadged McMartin MT-4’s.
https://groupdiy.com/index.php?topic=73580.msg935848;topicseen#msg935848
pins 1-3 7.5Ω DC = 125-150 pr
pins 1-4 16Ω DC - 600 pri
pins 5-6 139Ω DC = 10K bridging input
pins 8-9 91Ω DC = 10K sec
pins 2-9 349Ω DC = 60K sec
9 pin sockets frequently available NOS on ebay.
$100 plus shipping/insurance
Kenyon T-26 600:600
NOS/NIB. +24db, hum bucking construction, typical multiple tap coil, see UTC A-20 impedance diagram as example.
$40 plus shipping/insurance on 2 lbs.
Gates console transformer panel
All three measure 8R : 0.7DCR roughly, would appear to be 150:speaker Z. Possibly identical, with center piece having shielding to prevent crosstalk. Maybe perfect for Paul’s bass trick, speaker as microphone.
$30 plus shipping/insurance on 3 lbs.
Presto tube record lathe power amp output transformer and choke
From a model 88-A power amp, using (4) 6L6/807 type power tubes. Has plate cap attachment for use with 807 tubes, can be removed for standard wiring to 6L6’s. Also the transformers on the later 92-A/B models, which spec within 1dB 20-17K. output impedances of 500/250/15/6 ohms at 50W output. Choke is 10H. The last picture shows how it was used on the 92-A amp, with plate cap attachment.
http://www.hifido.co.jp/KW/G0105/E/0-50/C05-23362-51346-00/
http://www.steveespinola.com/lathetrolls/resources/Presto_92A_Manual_Schematic_gif.pdf
$200 plus shipping/insurance on some lbs; heavy.
(2) Thordarson PP 6V6 to 500 ohm output transformers
Great for Stalevel and other tube limiters or compressors. T-17S11. One is on a sub-panel which has a rotary switch to choose output impedances from 500/25016/8/4. Rated 15W, primary 8K.
$150 plus shipping/insurance on 7 lbs.
Tube output transformer for four 6L6
Apparently from a Baldwin organ with several references suggesting 40W power, tests fine for DCR, leads in good condition. Nice hefty chunk of iron for a power amp build. Part #512-14633D. Organs have to pass some low lows, so inductance should be better than average.
$40 plus shipping/insurance on 5 lbs
Pair of IOaudio input transformers for Pultec
As provided with his MEQ500 mid range Pultec project back in 2008 or so. They didn’t work for me as I was trying to use them with true 600 ohm source impedances, and they are somewhat rolled off on the bottom in that case. Feed them with a 50 ohm source such as many converters provide today, and they are full range on the bottom, with IOaudio measuring a -3dB point of 14Hz in that case.
$20 plus shipping/insurance on 1 lb.
RCA potted power transformers 70VCT 800mA
Multiple pieces of very nice potted/shielded power transformers for SS projects. Two are US voltage only, seven more that cover international voltage ranges.
$25/ea plus shipping/insurance on 5 lbs.
ADC HUM-1 video humbuckers
Off the audio path, into video. I have a number of these to sell. New in original shipping boxes. BNC connectors. Pass audio too, an interesting euphonic sound, probably from the low 75Ω loading.
Here's a typical ad for one at $160:
http://www.markertek.com/product/hum-1/adc-by-te-connectivity-hum-1-humbucking-coil
$30 + shipping and insurance. Slightly under 4 lbs / 1.8 kg shipping weight per piece.
---------recently sold-----------
UTC A-20
has some paint pulled off from tape, has connection labels added on side, with an original A-20 box. Tests fine.
$50 plus shipping/insurance
RCA OP-6 tube mic preamp input transformer pair
RCA OP-6 input transformer pair in good shape, ready to go into your two channel tube mic preamp build. Typical American impedance ratios of 30/250Ω to single tube grid use, center tap also available on the primary. Great classic sound. Tested for both resistance and inductance.
$295 plus shipping/insurance on 2 lbs.
OK, time to let some things go so they can be put back into use. Input, interstage, output, repeat coils, and power. Some singles, some pairs. In this issue:
RCA BA-3 program amp input and output transformer set
(2) RCA MI-38482 nine pin plug-in transformers (McMartin MT-4) tube inputs
Kenyon T-26 600:600
Gates console panel with 3 transformers
Presto PPP 6L6/807 tube record lathe power amp output transformer and choke
Thordarson PP 6V6 to 500 ohm output transformer pair, good for Sta-Level, etc
Tube output transformer for four 6L6
Pair of IOaudio input transformers for Pultec
RCA potted power transformers 70VCT 800mA
ADC HUM-1 video humbuckers
RCA BA-3 program amp input and UTC output transformer set
Indeed. Both test well. The BA-3 is a killer single ended high gain preamp with high max output level. The UTC output is NOS, very difficult to find a high level single ended output like this with good low frequency response. The input is in great shape.
Input is 150/600 to grid.
Output is for single ended 6V6 or 6L6 (RCA did both with this) to 600/150/15/7.5/5 at +30dBm with less than 1% THD 30-15K as used in a BA-3. Lots of BA-3’s in use for vintage audio speaker listening, especially with efficient horn systems.
$600 plus shipping/insurance on 9 lbs.
(2) RCA MI-38482 nine pin plug-in transformers
Accessory transformer for the 1970’s SA-115 transistor general use amplifier, which appears to be a rebadged McMartin unit. A good guess would be these are rebadged McMartin MT-4’s.
https://groupdiy.com/index.php?topic=73580.msg935848;topicseen#msg935848
pins 1-3 7.5Ω DC = 125-150 pr
pins 1-4 16Ω DC - 600 pri
pins 5-6 139Ω DC = 10K bridging input
pins 8-9 91Ω DC = 10K sec
pins 2-9 349Ω DC = 60K sec
9 pin sockets frequently available NOS on ebay.
$100 plus shipping/insurance
Kenyon T-26 600:600
NOS/NIB. +24db, hum bucking construction, typical multiple tap coil, see UTC A-20 impedance diagram as example.
$40 plus shipping/insurance on 2 lbs.
Gates console transformer panel
All three measure 8R : 0.7DCR roughly, would appear to be 150:speaker Z. Possibly identical, with center piece having shielding to prevent crosstalk. Maybe perfect for Paul’s bass trick, speaker as microphone.
$30 plus shipping/insurance on 3 lbs.
Presto tube record lathe power amp output transformer and choke
From a model 88-A power amp, using (4) 6L6/807 type power tubes. Has plate cap attachment for use with 807 tubes, can be removed for standard wiring to 6L6’s. Also the transformers on the later 92-A/B models, which spec within 1dB 20-17K. output impedances of 500/250/15/6 ohms at 50W output. Choke is 10H. The last picture shows how it was used on the 92-A amp, with plate cap attachment.
http://www.hifido.co.jp/KW/G0105/E/0-50/C05-23362-51346-00/
http://www.steveespinola.com/lathetrolls/resources/Presto_92A_Manual_Schematic_gif.pdf
$200 plus shipping/insurance on some lbs; heavy.
(2) Thordarson PP 6V6 to 500 ohm output transformers
Great for Stalevel and other tube limiters or compressors. T-17S11. One is on a sub-panel which has a rotary switch to choose output impedances from 500/25016/8/4. Rated 15W, primary 8K.
$150 plus shipping/insurance on 7 lbs.
Tube output transformer for four 6L6
Apparently from a Baldwin organ with several references suggesting 40W power, tests fine for DCR, leads in good condition. Nice hefty chunk of iron for a power amp build. Part #512-14633D. Organs have to pass some low lows, so inductance should be better than average.
$40 plus shipping/insurance on 5 lbs
Pair of IOaudio input transformers for Pultec
As provided with his MEQ500 mid range Pultec project back in 2008 or so. They didn’t work for me as I was trying to use them with true 600 ohm source impedances, and they are somewhat rolled off on the bottom in that case. Feed them with a 50 ohm source such as many converters provide today, and they are full range on the bottom, with IOaudio measuring a -3dB point of 14Hz in that case.
$20 plus shipping/insurance on 1 lb.
RCA potted power transformers 70VCT 800mA
Multiple pieces of very nice potted/shielded power transformers for SS projects. Two are US voltage only, seven more that cover international voltage ranges.
$25/ea plus shipping/insurance on 5 lbs.
ADC HUM-1 video humbuckers
Off the audio path, into video. I have a number of these to sell. New in original shipping boxes. BNC connectors. Pass audio too, an interesting euphonic sound, probably from the low 75Ω loading.
Here's a typical ad for one at $160:
http://www.markertek.com/product/hum-1/adc-by-te-connectivity-hum-1-humbucking-coil
$30 + shipping and insurance. Slightly under 4 lbs / 1.8 kg shipping weight per piece.
---------recently sold-----------
UTC A-20
has some paint pulled off from tape, has connection labels added on side, with an original A-20 box. Tests fine.
$50 plus shipping/insurance
RCA OP-6 tube mic preamp input transformer pair
RCA OP-6 input transformer pair in good shape, ready to go into your two channel tube mic preamp build. Typical American impedance ratios of 30/250Ω to single tube grid use, center tap also available on the primary. Great classic sound. Tested for both resistance and inductance.
$295 plus shipping/insurance on 2 lbs.