One of My MOST RECENT July 2021 Blues amp projects is this amp I made from a Hammond Organ amp with two 6bq5 / EL84s and one of my special design preamps. The 6BQ5s in this test are used, two different ones, but give that "Vintage Drive" tone. Later tests with two new husky SOVETEK EL84 tubes showed a much bugger sound with more clean power

Have been modding, repairing, restoring guitar amps since 1965, when I was around the Sunset Strip in Hollywood CA, at the end of the psychedelic era. I was in the same clubs as Jimi Hendrix, Jim Morrison and more.

I have done repair, custom mods, on many, many different amps through the years, Marshall mods, Harp amps, Rock amps, Guitar wiring mods etc.

Contact Troy at; Downey Music Center, 562-869-4485 in Downey CA

 

 

 

 This is a Radio Station Mixing Console made around 1945 - 47. It mixes three microphones, two pronograph turntables, (when a music record was played) and one line level signal. 

The mix is sent to, either out on the air, or back to the studio, or listening audience

I managed to get all of it running fine again, NO CIRCUIT INFO, and it sounded warm and smooth.

It had dual power supplies, a lot of 6sc7 tubes and a internal monitor amp and speaker.

Another Summer 2020 amp Mod job for one of the Carlsbad, CA 'Moose Lodge Players' amps was this Marshall 18 Watt amp. I made it cathode bias for more compression and smooth Blues Tone, all carbon resistors, and changed over to 7199's for a real 24 watts out.
 

 A recent modding job for a great Oceanside, CA player, is a Tweed Twin amp with four EL34 tubes in cathode bias for much less power and much more compression. Also using carbon resistors in the audio paths, the plate and cathode resistors etc. for big tone and smooth compression. A 12at7 driver and vintage 12ax7 tubes for the preamp. This was done at the http://tubeamprepairshop.com/ really messy bench, from the huge amount of amps that have been here before. Summer 2020

Yamaha PM1000 Transistor Mike Preamp wild Racking Projects

Here are some 'interesting' Yam projects

This is four channel rack job for a Italian customer

Below shows my placing the out transformer in the back

of the module so each one had both in/out transformers inside 

They had to be mounted on a frame  that was going into a wood box

Four XLR input jacks, and four TRS output jacks

 

 The 1/4" DI in jacks are at the bottom of the channels

You can see a black cable going to one jack

I added a passive EQ from a old tube stereo console

This allowed the owner to be able to patch it in to add some

Vintage 'Smooth' tone to any sound

Below shows measuring things out

The below shows measuring and drilling out the Hammond

16" wide by 8" deep by 3-1/2" high box for two rack jobs at a time

This was one way to keep up with orders and make sure both were

drilled out and all parts placed in the same places.

I replaced the output transistors with lower gain bigger power

transistors and increased the idle to get more power, less noise and

a much bigger, tighter sound, and nice round tone Hi-Fi bass

This unit used EDCOR 600 ohm line out transformers

These 'step-up' the signal three times more for up to +28DB levels

out, and the line stage runs at three times less gain for less noise 

 

Any questions or interest in projects?

George at ElectricEther@yahoo.com

Vista, CA 92084

Microphone preamps transistor and vintage tube style

One of over 30 stereo mike preamps I made for Tape-Op customers 
 Preamps have Tamuri transformers, phantom, pad, and Di in jacks

60Db gain max, over 22DB levels into 600 ohms

The PM1000 board is center, one gain stage per side, In and out transformers are back right and left sides

There is a diode coming from the DC in jack, (middle back), to prevent reverse polarity

I used camera tape to “stick” all the wires down, as Cam tape not gooey

The level control, (upper right front) a 600 ohm pot, is feeding the 600/600 ohm line out transformer through a two watt, 10 ohm, carbon resistor. The slowness of the carbon resistor adds some warmth. 

The gain stages have a push-pull output stage, that can drive approx 22 volts into 67 ohms RMS, so the 300 ohm load not a problem. The shiny TO-5 transistors are the new ECG NPN/PNP outputs. I used good audio quality Xicon “Reds”, aluminum electroylitics in the signal path. They were the best a few years ago, now the ELNA Silmic and Cerafine caps are way above any of these for audio quality

This is a old Altec transister PA amp being turned into a Mike Preamp and power supply for five other  mike preamps. I had the engraved labels made to get a 'Pultec look' for the panel.

               Here is the new inside, the PM1000 board with two gain stages mounted to the front. 
    The yellow inter-stage transformer is in the center front, the in transformer is at upper left on the back of the front panel. This transformer adds 'smooth' to the sound and more gain without noise.
               Power supply, feeding to the barrier strip, is upper middle, on the back, and right. 
     The power supply in the Altec provided +44 for the preamps, and +48 for the phantom power

  Here you can see the VU at "O" VU which is set for "O" VU = +4 level out
I test every preamp at +12DB levels out to see that the line out stage 

has headroom over +12db into 600 ohms. 

Here are some pics of some basic steps to 'racking' two Yamaha PM1000 

or any mixing console 'channel strips'

Step one is getting everything lined up and where doe it go? questions answered

Making sure the front and back panels are perfect most important

If a hole is just a bit to far off on the front, it can not be fixed

A trick way to mark the holes on the front side

One channel ready to be mounted

The one pot will be replaced with a EQ - In/Out switch

Punching holes with a chassis punch once pilot holes are drilled

Two channels mounted with fresh screws from the back

 Now that all the holes have been drilled or punched, all the parts can be mounted 

with no worries as to proper placement

I built a whole series of thee 19" by 3-1/2" rack mount

chassis stereo preamps with the talkback yam boards. These boards

have two 'Gain Stages' on each board, so you just need a input transformer

 gain, level, phantom power controls, DI input and a output transformer

This is one of a series of 19" by 1-3/4" single - space rack mount stereo preamps

I built with a new board I designed that has a Modded PM1000 'Gain Stage'.

This board has the basic setup with, Left to Right

Mike balanced in, Pad-off, -12, -20db, DI-input, Level, Phantom power on/off

Gain, and a sweet vintage SONY 600 ohm line out transformer

 The board has a +48 volt power supply filter, phantom power feed, 

Balanced input stage on the top left, phantom and pad on the lower right

and the 'Line Gain Stage' on the lower left.

The four transistor 'Gain Stage' has been modded by; 

a. changing the two output transistors to lower gain/higher power versions

that increases the big warm tight sound, raises the maximum output level, 

and lowers the noise. b. using metal film resistors for lower noise, c. the board 

has pads for radial electrolytic caps or metallized polyester caps.

The metallized polyester caps have a clearer, 'Tube Amp" sound 

A board under test, the VU is set for "O" VU  +4 level out

This new board can drive down to 56 ohms and can drive a 

step-up line out transformer for +28DB out levels, and tons

of NEVE sounding headroom.

The two round 'metal - can' transistors are NTE great big and warm
sounding transistors. They are idling at almost one-half watt each.
This gives the 'Gain Stage' a big tight bass and a strong clean sound.
The 'Gain Stage' is also noiseless.

This is the true - balanced in stage that is super quiet
It has a unbalanced out to the level control, or line in
selector switch, and about 20DB gain.

 

The phantom power, two stage pad, and click filter is shown

here on the lower left corner. The balanced mike in goes through

the pad/phantom circuit, and then to a mike in transformer, or the 

transformerless balanced in preamp

This stereo preamp has a switch, Pr/Mix on the lower right, 

that selects the mike/Di inputs, or two RCA jacks on the back that

allow you to hear your mix on your headphones. 

The  'Gain Stages' make great headphone amps for higher 

impedance headphones

 

There is a +4 red LED for each channel

=============================================================================

The preamp below is one of a series of "Classic 3-stage tube mike preamps

I built using all vintage parts including vintage tubes.

  This classic circuit is given more headroom by using two #76 triodes 

in parallel to drive the 15k/600 ohm Altec 'Red' line out transformer

This gave these preamps a comfortable +15DB out without clipping

One of a pair of custom tube mike preamps built for a customer

Unit has Vintage or NOS preamp tubes, wide range gain control

Russian paper-oil caps, all vintage parts including the knobs

These preamps (above/below) have a vintage 39/44 tube or a rare EF40 tube
 which is equal to a EF86, as the pre stage
 You can switch tubes without clicks while the preamp is active

One 6sn7 as a Class-A driver is coupled to a large Philips line out transformer 
on the right side of the chassis. The gray box is the line out transformer

The big 1930's 39/44 tube is by the Altec 'green' input transformer on the left

This preamp has all paper-oil caps, and three gain controls that give a 
great range of gain and overall sound of the preamp