Tech Studies

This old radio was £20 but good condition in a dog charity store. It has a full valve compliment so seemed worth the risk. I don't have much test gear these days, so did what checks I could with what I have and no oscilloscope. I decided to go ahead and do what I can ... 1946 Vidor Chanson CN349 Valve Radio Checks

From the Sony EX50 Specs, 110W RMS continuous into 6 ohm, TAM transformer, has a 28V RMS winding, giving about a 36V peak DC ouput after rectification in reality (now built, it shows this). The continuous AC speaker output is 110W/V = 4A Max. Should be OK to charge a car battery, not great. Will ... Car Charger from Sony EX50 Transformer

Lots of attempts getting this to work with a car bulb, then got a small 36 ohm 12V panel bulb in a box of bits, which finally burst into life using an LM358N op amp, not Carlson's TLO72 op amp. Mine worked without the trim pot from ground to pin 3 - a 1k5 only ... Mr Carlson’s Lab – 1kHz Wien Bridge Oscillator

I jumped at this Ebay bargain knowing that Gibbs reverbs of this size are about US$50 or more, and then there are the import fees. I expected this old one to sound as nice due to its size. A few things I want to document for future regarding the input and output sides of different ... Laney Vintage Reverb Tank Notes

SUMMARY FIRST DUE TO MY STUPIDITY - I COULD HAVE HAD IT GOING 2 DAYS BACK WITH BETTER REASEARCH ON 6AX7 heaters to realise why triode 1 was not working and NOT assuming the original valve was dead when tested in a normal amp - it was fine! Dick... What Modder's need to know that ... Biyang ODT100 Valve Pedal Repair and Modding Options Study

After having the resonance feedback type scenario through the cab speakers at high volumes and thinking the issue may have been sound feedback and there is nothing wrong, I looked for other issues possibly affecting the output tubes just to be sure before re-assembly and found a burnt resistor R83 at the cathode of one ... 2008 Carlsbro TC60 Repair – Fixed

This thing came out in 2008 it seems: https://www.performing-musician.com/pm/aug08/articles/carlsbrotc60.htm Tech Spec TC60 60W all-valve combo. Two EL34 output valves. Four 12AX7 preamp valves. True class A/B operation. Twin channel (clean, lead). 1 x 12-inch speaker. Classic three-band passive EQ. Series/parallel switchable FX loop. Accutronics licensed spring reverb. Extension speaker output. Dimensions (WDH): 594 x 305 ... 2008 Carlsbro TC60 Repair – Part 2

This thing came out in 2008 it seems: https://www.performing-musician.com/pm/aug08/articles/carlsbrotc60.htm Tech Spec TC60 60W all-valve combo. Two EL34 output valves. Four 12AX7 preamp valves. True class A/B operation. Twin channel (clean, lead). 1 x 12-inch speaker. Classic three-band passive EQ. Series/parallel switchable FX loop. Accutronics licensed spring reverb. Extension speaker output. Dimensions (WDH): 594 x 305 ... 2008 Carlsbro TC60 Repair – Part 2

Having a repair job on another one of these models gives me the chance to learn about the one I already have, which I did not have to look when I bought it, as it was fully working already. A comparison of two similar amps is always interesting too - any major component changes, power ... Carlsbro TC60 Repair and Design Study – Part 1

Having a repair job on another one of these models gives me the chance to learn about the one I already have, which I did not have to look when I bought it, as it was fully working already. A comparison of two similar amps is always interesting too – any major component changes, power ... Carlsbro TC60 Repair and Design Study – Part 1

This is another vintage classic from John B's collection for repair. A 1960's model - it looks like a Blonde with the light colour cloth - with the label still intact - model 6G9B. This amp is in a sorry state due to an incorrect OT amongst other things: The choke serial number is 1253C3A. ... 1962 Fender Tremolux Repair

I thought I would cover this topic as there are many students - musicians, DJ's and budding live music sound or stage monitor techs - I see at college who don't have even a basic electronics or physics education, that may need to understand some of the concepts behind connecting sound systems together, for safety ... Understanding Speaker Cab 16, 8 and 4 Ohm Connections

I found a couple of small schematic errors that had me head scratching a bit trying to follow the Normal and Klipp channel outputs. This was a presumption of pin numbers at valves 1 and 2, which I have rectified by re-connecting them correctly in the diagrams in this section, as well as the PT ... Laney Klipp 100W Repair and Design Study – Part 2

I found a couple of small schematic errors that had me head scratching a bit trying to follow the Normal and Klipp channel outputs. This was a presumption of pin numbers at valves 1 and 2, which I have rectified by re-connecting them correctly in the diagrams in this section, as well as the PT ... Laney Klipp 100W Repair and Design Study – Part 2

DISCLAIMER:- - - - READ THIS!!! https://stevepedwards.today/en.wikipedia.org/wiki/Electric_shock There is a big effect difference between voltage levels that break through the skin conductivity - which happens to be in the 400 to 500V +DC range of our valve amp circuits! BE CAREFUL! Drain and check WITH A METER the PT secondary capacitors when the circuit is off before touching components ... Laney Klipp 100W Repair and Design Study – Part 1

DISCLAIMER:    READ THIS!!! https://stevepedwards.today/en.wikipedia.org/wiki/Electric_shock There is a big effect difference between voltage levels that break through the skin conductivity – which happens to be in the 400 to 500V +DC range of our valve amp circuits! BE CAREFUL! Drain and check WITH A METER the PT secondary capacitors when the circuit is off before touching components ... Laney Klipp 100W Repair and Design Study – Part 1

I want to get to grips with the topic of passive filters - operation, maths and values in amps generally to better read what frequencies are passing to or being blocked between stages. No doubt I will wonder off at tangents as usual... I'll look at "[fc]...which is the frequency that the filter will attenuate ... Passive Filters, Capacitors, Smoothing and Noise in Amps

NB: 6/1/14 When I started this Post I didn't expect how long but interesting and rewarding it would be - to study this whilst applying the Load Lines to a real world scenario - the Maggie amp. Trying to solve its early volume level distortion problem was the perfect opportunity for this topic as I ... Understanding Amp Load Lines

Amp Power Output Calculations PP18 Power Calculations Using the Aiken amp info from the Q+A page here: https://www.aikenamps.com/TI_Aiken_Q&A.html It is possible to check accurately, the power output of your amp with a dual beam oscilloscope, and knowing the speaker impedance you are connecting to. The rest comes from calculation as stated in the above article. ... Amp Power Output Calculations

29/12/13- - - - - - - - Global Negative Feedback on the PP18 I returned to the noisy rectifier hash ridden PP18 problem as it was still bothering me immensely not knowing the exact cause, and not having a suitable fix more so. I re-read the global negative feedback pages 164 and 188 of Blencowe but was still wondering if it was ... Global Negative Feedback on the PP18

I am going to just add stuff like vids and schematics to this Post over time maybe, as there was no need to do a real in depth check of this amp before getting it going, as the bay seller had fired it up, got no sound then sold it as a spare/repair: ----------------------- ORIGINAL ... Carlsbro CS60 Reverb Mk II PA Repair

3 I reversed the image in MSPaint so I can build and test mine left to right from Mains PT on, in logical stages. This is less tedious though takes much longer, but you learn and think more about how each stage works. Also, if there is a fault, you need only look as far ... PP18_6V6 Build Summary

  1967 Marshall JMP 100W Buyer's Info ---------------------------------------------------------------------- DISCLAIMER This amp is not my property and I am selling it on behalf of the owner via my Ebay account. Do not contact me with complaints or technical problems after sale – be prepared to get it professionally serviced before use. I am being honest and ... 1967 Marshall JMP 100W Buyer’s Info

  1967 Marshall JMP 100W Buyer's Info ---------------------------------------------------------------------- DISCLAIMER This amp is not my property and I am selling it on behalf of the owner via my Ebay account. Do not contact me with complaints or technical problems after sale - be prepared to get it professionally serviced before use. I am being honest and ... 1967 Marshall JMP 100W Buyer’s Info

Marshall 100W Mains Tests Data I was a bit thrown by the low DC resistances of the windings of this at first, as 2-5 ohms seems really low compared to the smaller Danbury transformers I have measured (30 ohms primary, or so), so I removed it to test it properly using a Variac. I initially ... Marshall 100W Mains Tests Data

This section was heavy going for a LOT of reasons. I think I will have to start backwards from where I am, with a working amp, as a lot was researched and some components changed to get to this point - probably in error overall from what is actually necessary - but that's learning. That's ... Handbook Amp Project – Part 5 – Output Section – Working Amp

This section was heavy going for a LOT of reasons. I think I will have to start backwards from where I am, with a working amp, as a lot was researched and some components changed to get to this point – probably in error overall from what is actually necessary – but that's learning. That's ... Handbook Amp Project – Part 5 – Output Section – Working Amp

NOTE: I can make no guarantees for the accuracy of following component values and ratings - it is a guide ONLY for those Marshall tech fans and experts to cross reference if they wish, from what I have seen in this Marshall alone. I have no prior knowledge or experience on this Marshall or any ... Marshall JMP 100W Super Lead – Serial 10928 – Components List

NOTE: I can make no guarantees for the accuracy of following component values and ratings – it is a guide ONLY for those Marshall tech fans and experts to cross reference if they wish, from what I have seen in this Marshall alone. I have no prior knowledge or experience on this Marshall or any ... Marshall JMP 100W Super Lead – Serial 10928 – Components List

Gibson GA 15 Amp Repair My old college chum, John Bickersteth (Lazy Lester, Incredible String Band) brought me his 15W valve amp, as it has a blown EL84. It's an opportunity to get a look at another design of amp for me, and do him a favour also. I got it complete with cobwebs and ... Gibson GA 15 Amp Repair

Amplifier Output Frequency Responses I thought it would be helpful while doing the Output Section Posts to log some data for my different amps output stages, either across the 6V6 anode, the 8/16 Ohm speaker output or both, depending on accessibility to the leads etc. I'm not taking them apart to do it! In the ... Amplifier Output Frequency Responses

NOTE on terminology - I have learned to NOT use the terms "Earth" and "Ground" interchangeably. They are functionally different electrically: https://www.valvewizard.co.uk/Grounding.pdf An Earth is a voltage reference point (Planet Earth and 0V usually) and a connection point for equipment electrical safety. The connection to Planet Earth at some point is made by driving a ... Handbook Amp Project – Part 4 – Input Section

NOTE on terminology – I have learned to NOT use the terms "Earth" and "Ground" interchangeably. They are functionally different electrically: https://www.valvewizard.co.uk/Grounding.pdf An Earth is a voltage reference point (Planet Earth and 0V usually) and a connection point for equipment electrical safety. The connection to Planet Earth at some point is made by driving a ... Handbook Amp Project – Part 4 – Input Section

The Rectifier Diodes For valve or most transistor and Integrated circuit based appliances like radios and PCs to work, high 240V mains voltage usually needs to be converted to DC that has no varying aspect (ideally) to it. This is done by components in the Rectifier section of the circuit. The rectifier section converts a ... Handbook Amp Project – Part 3 – Rectification

The Rectifier Diodes For valve or most transistor and Integrated circuit based appliances like radios and PCs to work, high 240V mains voltage usually needs to be converted to DC that has no varying aspect (ideally) to it. This is done by components in the Rectifier section of the circuit. The rectifier section converts a ... Handbook Amp Project – Part 3 – Rectification

DISCLAIMER: The following is NOT to be taken as a definitive procedure for building or repairing ANY electronic device and the author takes NO responsibility for any damage or injury that results from anyone using this guide. It is intended for educational purposes ONLY. If you have ANY doubt about building or making modifications or ... Handbook Amp Project – Part 2 – Mains Electricity and Transformer

DISCLAIMER: The following is NOT to be taken as a definitive procedure for building or repairing ANY electronic device and the author takes NO responsibility for any damage or injury that results from anyone using this guide. It is intended for educational purposes ONLY. If you have ANY doubt about building or making modifications or ... Handbook Amp Project – Part 2 – Mains Electricity and Transformer

Guitar Amp Handbook Amp Project - Part 1 I bought this book by Dave Hunter, months ago, and it is a really good read if you are into valve amps, as it is more or less a historical tree of the key amp designs starting with the 1956 Fender 5E1 Champ. There is also a ... Handbook Amp Project – Part 1 – Chassis

Guitar Amp Handbook Amp Project – Part 1 I bought this book by Dave Hunter, months ago, and it is a really good read if you are into valve amps, as it is more or less a historical tree of the key amp designs starting with the 1956 Fender 5E1 Champ. There is also a ... Handbook Amp Project – Part 1 – Chassis

I needed to get the Marshall as good as I can for my level of amp repair knowledge, as it has been bugging me for ages as a loose end since the main "just get sound out of it" repair was done months back - the Marshall Repair Posts. It became even more of an ... Correcting the Marshall Tremolo Circuit

Amplifier Jack Socket Stomp Switch Variations Do you have an amp with no footswitch, but are put off by the sometimes extortionate prices for manufacturer's Name replacements, even used ones on Ebay? Have you considered building your own? It may be really simple, if you have a chassis, can solder and have a drill. I ... Amplifier Jack Socket Stomp Switch Variations

Ibanez Five Position Switch Nightmare 12/5/12 I thought I would document a little of my frustrating (but ultimately rewarding) experiences yesterday and today, of changing my noisy guitar switch for an Ebay replacement. You may save some trouble if you are doing this yourself, by NOT making some of the mistakes I made. The rewarding ... Ibanez Five Position Switch Adventure

Waveforms Revisited - AM and FM Modulation using Synthmaker As I am doing a synth programming module at college, that covers the basics of sound wave modification, I thought a general re-cap on general wave theory would not hurt, as it applies to sound synthesis. A prior Post covers these and other aspects of waveforms ... Waveforms Revisited – AM and FM Modulation using Synthmaker

Waveforms Revisited – AM and FM Modulation using Synthmaker As I am doing a synth programming module at college, that covers the basics of sound wave modification, I thought a general re-cap on general wave theory would not hurt, as it applies to sound synthesis. A prior Post covers these and other aspects of waveforms ... Waveforms Revisited – AM and FM Modulation using Synthmaker

Addendum to Test Tone Using FLS - Synthmaker I've been struggling to find the right components to alter frequency in Synthmaker, as a better way to generate an audio Test Tone using FLS, than the previous example I gave in the other Post. No doubt there are better ways, but for now, this circuit gives ... Addendum to Test Tone Using FLS – Synthmaker

Fender Champ 12 Repair ---------------------------------------------------------------------------- Addition 6/6/13 READ THIS!!! https://stevepedwards.today/en.wikipedia.org/wiki/Electric_shock There is a big effect difference between voltage levels that break through the skin conductivity - which happens to be in the 400 to 500V DC range of our amp circuits! BE CAREFUL! Drain the secondary capacitors when the circuit is off and always check ... Fender Champ 12 Repair

Amp Related Circuit Basics - Transformers, Rectifiers and Capacitors I thought I would write a set of Posts on some basic aspects of electronics that are common to most circuits in one way or another, but leaning more toward actual valve amp circuits where possible. This is to help fix things in my mind as ... Amp Related Circuit Basics – Transformers, Rectifiers and Capacitors

Amp Related Circuit Basics – Transformers, Rectifiers and Capacitors I thought I would write a set of Posts on some basic aspects of electronics that are common to most circuits in one way or another, but leaning more toward actual valve amp circuits where possible. This is to help fix things in my mind as ... Amp Related Circuit Basics – Transformers, Rectifiers and Capacitors

Ashdown Fallen Angel Repair 17/1/13 --------------------------------------------------------------------------- Addition 6/6/13 READ THIS!!! https://stevepedwards.today/en.wikipedia.org/wiki/Electric_shock There is a big effect difference between voltage levels that break through the skin conductivity - which happens to be in the 400 to 500V DC range of our amp circuits! BE CAREFUL! Drain the secondary capacitors when the circuit is off and always ... Ashdown Fallen Angel 40W Repair

Using FLS As A Test Signal Generator With DSO Nano 13/1/13 ——————————————————-————————————————————————— DISCLAIMER: The following is NOT to be taken as a definitive procedure for repairing ANY electronic device and the author takes NO responsibility for any damage or injury that results from anyone using this guide. It is intended for educational purposes ONLY. If ... Using FLS As A Test Signal Generator With DSO Nano

Applying the Briggs Valve PDF Principles to the Marshall Circuit On reading the Briggs pdf document, I thought I would try to relate some of the general nuts and bolts principles as I come across them or try to understand them, as laid out in Briggs' comprehensive text, to the real circuits I have covered ... Applying the Briggs Valve PDF Principles to the Marshall Circuit

Aston Electronics 5W Valve Amp Kit Build - Finished --------------------------------------------------------------------------- Addition 6/6/13 READ THIS!!! https://stevepedwards.today/en.wikipedia.org/wiki/Electric_shock There is a big effect difference between voltage levels that break through the skin conductivity - which happens to be in the 400 to 500V DC range of our amp circuits! BE CAREFUL! Drain the secondary capacitors when the circuit ... Aston Electronics 5W Valve Amp Kit Build – Finished

Aston Electronics 5W Valve Amp Kit Build - Start --------------------------------------------------------------------------- Addition 6/6/13 READ THIS!!! https://stevepedwards.today/en.wikipedia.org/wiki/Electric_shock There is a big effect difference between voltage levels that break through the skin conductivity - which happens to be in the 400 to 500V DC range of our amp circuits! BE CAREFUL! Drain the secondary capacitors when the circuit ... Aston Electronics 5W Valve Amp Kit Build – Start

Marshall Mercury 2060 - Repaired!! --------------------------------------------------------------------------- Addition 6/6/13 READ THIS!!! https://stevepedwards.today/en.wikipedia.org/wiki/Electric_shock There is a big effect difference between voltage levels that break through the skin conductivity - which happens to be in the 400 to 500V DC range of our amp circuits! BE CAREFUL! Drain the secondary capacitors when the circuit is off and always ... Marshall Mercury 2060 – Repaired!!

Marshall Mercury 2060 – Repaired!! --------------------------------------------------------------------------- Addition 6/6/13 READ THIS!!! https://stevepedwards.today/en.wikipedia.org/wiki/Electric_shock There is a big effect difference between voltage levels that break through the skin conductivity – which happens to be in the 400 to 500V DC range of our amp circuits! BE CAREFUL! Drain the secondary capacitors when the circuit is off and always ... Marshall Mercury 2060 – Repaired!!

Marshall Mercury 2060 Repair - Week 2-3, Circuit Theory ---------------------------------------------------------------------------------------------------------------------------------- DISCLAIMER: The following is NOT to be taken as a definitive procedure for repairing ANY electronic device and the author takes NO responsibility for any damage or injury that results from anyone using this guide. It is intended for educational purposes ONLY. If you have ... Marshall Mercury 2060 Repair – Week 2-3, Circuit Theory

Marshall Mercury 2060 Repair – Week 2-3, Circuit Theory ---------------------------------------------------------------------------------------------------------------------------------- DISCLAIMER: The following is NOT to be taken as a definitive procedure for repairing ANY electronic device and the author takes NO responsibility for any damage or injury that results from anyone using this guide. It is intended for educational purposes ONLY. If you have ... Marshall Mercury 2060 Repair – Week 2-3, Circuit Theory

Marshall Mercury 2060 Repair - Days 4-6 ---------------------------------------------------------------------------------------------------------------------------------- DISCLAIMER: The following is NOT to be taken as a definitive procedure for repairing ANY electronic device and the author takes NO responsibility for any damage or injury that results from anyone using this guide. It is intended for educational purposes ONLY. If you have ANY doubt ... Marshall Mercury 2060 Repair – Days 4-6

Marshall Mercury 2060 Repair – Days 4-6 ---------------------------------------------------------------------------------------------------------------------------------- DISCLAIMER: The following is NOT to be taken as a definitive procedure for repairing ANY electronic device and the author takes NO responsibility for any damage or injury that results from anyone using this guide. It is intended for educational purposes ONLY. If you have ANY doubt ... Marshall Mercury 2060 Repair – Days 4-6

DISCLAIMER: The following is NOT to be taken as a definitive procedure for repairing ANY electronic device and the author takes NO responsibility for any damage or injury that results from anyone using this guide. It is intended for educational purposes ONLY. If you have ANY doubt about making modifications or repairs to your own ... Marshall Mercury 2060 Repair – Days 1-3

DISCLAIMER: The following is NOT to be taken as a definitive procedure for repairing ANY electronic device and the author takes NO responsibility for any damage or injury that results from anyone using this guide. It is intended for educational purposes ONLY. If you have ANY doubt about making modifications or repairs to your own ... Marshall Mercury 2060 Repair – Days 1-3