Power Amplifier Speaker Output Headphone Adapter DIY

I was wondering if it was possible to drive a pair of regular dynamic headphones from a power amp such as my Class A F5. Sometimes I have periods of time without a pair of speakers such as if I have sold them and looking for something new to replace them with. In the meantime it would be nice to use a pair of headphones which quite frankly are hard to beat with most speakers. It seems that you need to spend quite a few more in pennies on the speakers to match even a modest pair of cans and once you are in the realms of higher end headphones then most speakers don't come close to the same levels of enjoyment and immersion in the music.

Speaker Output Headphone Adapter
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Grado RA1 Headphone Amplifier Clone DIY

Fancy making your own Grado RA1 amplifier clone. Well the circuit below is all you need. About £10 worth of electronic parts minus the case and regulated supply. Also very easy to make on veroboard or protoboard. The original circuit came from diyaudioprojects.com who I understand reverse engineered an original RA1. The design can be easily altered to use other better quality op-amps and more importantly E24 series preferred resistor and cap values.

The opamp used is the LM4562 or better still the OPA2134. You can use the cheaper original JR4556 but the OPA2134 should be easier to buy and is much higher quality than the JR4556.

Grado RA1 Headphone Amplifier Clone
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Teac VRDS T1 / Copland 288 - CMK-4 Mechanism (Broken Gear Repair)

The Teac VDRS CMK-4 mechanism is used in the following CD Players :-

Copland 288
Copland 277
TEAC VRDS-7
TEAC VRDS-T1
WADIA 6
WADIA 8
WADIA 21
WADIA 850 (Version a mech)
Krell KAV-300
 

My Copland CDP

My Copland 288 started to shred teeth on gear B. I needed these assembly drawings to work out that is was called gear B and what to order from CHS. Emailing absolute sounds proved to be useless as I expected from past experience regarding their support. Anyhow, not too difficult to replace both gear A and B once you know how to. The original gear had turned very yellow and soft. A common fault with some Teac mechanisms.

VRDS Copland 288 - CMK-4 Mechanism
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Audio Note Kondo M77 Tube Pre-amplifier Clone DIY

I have just converted my 12B4 tube pre-amp to this Audio Note M77 Clone. The 12B4 / 12B4A circuit was my reference bettering all other tube pre-amps I have owned in the past but this just betters it in so many ways. The circuit was linked from another overseas forum over at DiyAudio. Someone had opened up a real Kondo M77, took photos and traced the circuit plus measuring all voltages sketching this onto lined paper. I have re-drawn the original circuit in X-Circuit and the supply I used. The M77 is built to such as high standard using quite special parts, with an equal special price that most of us could never afford or justify.

 

Tubes (Single or Parallel)

Audio Note Kondo M77 Tube Pre-amplifier
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Yamaha A-S1000 Integrated Amplifier Review

I managed to pick up one of the retro styled Yamaha A-S1000 integrated amps at a good price off eBay. I first spotted these in the windows of Practical HiFi and Sevenoaks and was taken back by the build quality and looks for the price. Furthermore I wanted an amp with tone controls and an headphone output. Yes... you read right... 'Tone controls'. Even in my narrow music tastes of Berlin School, Electronic and Ambient etc there is a wide range of mixes in that some sound lean and others the opposite; so I thought tone controls could be useful. Also the Radio seems to vary widely especially between daytime and night-time shows. Most daytime shows on Radio 2 sound more compressed and lacklustre compared to later shows at night so another reason for trying tone controls out.

Yamaha A-S1000 Integrated Amplifier

MegaClamp Clone DIY Mains Filter

It is possible to make something similar to a Russ Andrews Mega Clamp or the Super Clamp at a lower cost. The purpose of any clamping device such as this is to clamp very high voltage spikes on the mains to limit them entering equipment. A typical spike protector power strip or plug in box is built using Metal Oxide Varistor's (MOV). The cheapest kind use just one clamping device, usually a single varistor between L-N. A better protector will use at least three MOV's, between L-N, L-E and N-E. However, varistor's degrade over time with repeated clamping of spikes, therefore rather than using just 1 or 3 components I have used a bank of 10 in this build, you can use more if you wish.

MegaClamp Clone
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Symphonies Plus Tube Pre-amp Review and Upgrades

The Symphonies Plus Vacuum Tube Pre-amp is made and sold by YS audio as a level 2 product for around £490 + duty and taxes in the UK.  It was originally cheaper at just over £200 but they seem to have increased the price late 2009. YSA have a scale of 1 to 4 for their products and they sell a number of pre-amps and power amps at various levels of internal parts quality and upgrades.

Symphonies Plus Tube Pre-amp

Nelson Pass B1 Buffer Pre-Amplifier DIY

I decided to make a B1 buffer for my Nelson Pass F5 power amp after listening to a friends version. The B1 is a no feedback JFet buffer that offers low distortion and noise with a very wide bandwidth. Being a buffer it has no gain and just acts as an impedance matching device with a volume control. It is really a source follower and outputs less than its input at less than full volume. It can be used between any source component and power amplifier and even used with another active stage. For example I have used it between my tube pre-amp and the power amp with the volume on the B1 set at maximum so it just acts as the impedance matcher. It is fairly easy to make and if you wish can be run off 2 x 9v batteries in series or a simple brick wall power supply that outputs 18 to 24V.

Nelson Pass B1 Buffer Pre-Amplifier
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Diy HiFi Supply EZ Preamp Kit

The EZ kit from Diy HiFi Supply is a a linestage pre-amp with an adjustable gain from 6, 12, 18, 22 and 30db. Input impedance is 400k+ depending on the gain setting chosen and consequently measurements vary with different tubes fitted. This is not my own unit but for Val I know who asked me to build this pre-amp with some special custom modifications.

Upgrades :-

Blackgate PSU Caps for HT and Heaters
Calrity Caps for Audio Coupling
Wima FKP Flim PSU By-Pass Caps
Gold Plated Silver Audio Wire in Teflon
Seiden Selector Switch
Japanese Step Attenuator
Silver WBT Style RCA Sockets
Custom Made Wooden Knobs
 

Sound

Diy HiFi Supply EZ Preamp Kit
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Nelson Pass F3 Class A Single Ended Amplifer DIY

When I was building my Nelson Pass F5 power amplifier, a Friend (Dave H) was building his F3 at the same time. This is the result, using the same Italian Made case as the F5. The F3 is again a class A design like the F5 but that is where the similarity ends, the F3 being 15W single ended were-as the F5 is 25W push pull. The F3 output is Capacitor coupled since it uses a single rail power supply were-as the F5 needs a split rail supply. Also due to the F3 lower power output it better suits an easier load were-as the F5 is a little more forgiving.

Nelson Pass F3 Class A
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