maza Front | Studio | DIY Audio Gear | My CD's

Things I've built

I've been building quite a lot of audio gear for my own use. And actually some of my friends, too, have got some stuff made by me for their use.

Current projects

Currently I'm working on the most complex amp I've done; it's going to have dual channel preamp (Dirty/Marshall and Clean/Fender channels, switchable), a tube buffered FX loop and a power amp with both EL84's and 6V6's (individual volume control for both tube pairs) for really flexible sound shaping and different amount of power (15-30W).

Fender Vibrolux (pics)

For a long time I've wanted to build the perfect amp for the Rhodes piano. I understood a long time ago that push-pull 6V6 output stage with bias modulating tremolo would be the key for the sound I wanted. I got some parts (chassis, turret board, pots, transformers, tube sockets, tubes) for almost free and decided to use them for this. The circuit is almost identical to the 5F11 version except that I used 5AR5 rectifier for higher B+ (and more output) and built the typical bass & treble controls instead of single tone pot. Result: brilliant amp.

Markku

"Markku" was originally a 200-watt, class-B amp (quad EL34's) which was badged as "Super City". I rebuilt it completely. Now it has 2 or 4 6550's on the output stage - one pair gives about 80 watts, two pairs ~120 (since the plate voltage drops quite a bit when more stress is put on the transformers). The preamp is basic two-stage pre, made with one ECC83. The phase inverter is an ECC83 as well. Btw. - You may wonder where did such a weird name come from? The answer is that the amp is used as a bass amplifier by Markku Halinen, bass player of Pin Ion. Together with the legendary Ampeg 8x10" cabinet, it really makes your balls shaking... :D

Radio Amplifier #2

I recently (or actually it took more than two years from the beginning to the end, the total working time was anyway less than 6 hours) finished an amp mostly built from parts of a tube radio for H-P Poikonen, the singer & guitarist of Pin Ion. The design was based on the AX84 P1 Extreme: one ECC83 on the preamp and an octal socket of the power tube. A 6V6 is used at the moment. This amp is brilliant for the classic blues & rock tones of the 70's. And this confirms that 6V6 is my favourite power tube. :-) H-P's page about the amp

Fender-like ~50 watt guitar amp (pics)

Someone in muusikoiden.net (Finnish website for musicians) was looking someone to rebuild his Peavey Classic 50. After some discussions he decided that he wants a completely new amp with great clean sound. Everyone knows that there's nothing better than a Fender clean, so my plan was to make a hybrid of several different Fenders. I ended up with Twin Reverb -like topology with Bassman EQ, Vibrolux bias-modulating tremolo and own bias circuit. Sound is - well - very Fender. :) What a great sound with Rhodes and 6V6 output tubes instead of the 6L6's.

EL84/6BQ5-based 20w guitar amp

My cousin wanted a good guitar amp (which he then didn't buy, since he didn't got the cash, heh...) so I built one. This is a mixture of several different vintage amps (Fender, Marshall, Hiwatt, Vox) and my own design (power amp).

Feature list

I reworked this amp somehow recently (Oct 2005). I tried to achieve as good clean sound as possible and the results are pretty nice. Practically I lowered the gain a bit, replaced most of the signal cables with shielded ones, replaced the EZ81 rectifier with silicon diodes (and a power resistor), installed 470 uF cap as the main filter plus a couple of 22 uF's for decoupling the preamp stages. I've been using this amp now for a couple of weeks with my Rhodes piano and the sound is better than ever. Amount of hum and noise is very small. I'm currently using two used Mullards as preamp and PI and new JJ's on the output stage.

A 6AK6-based, 2-watt push-pull guitar amplifier (pics power amp schematic)

I wanted a good-sounding amplifier at low volume for my organ at home. The 10-watt Philips amplifier I had rebuild earlier was definetely too loud, especially becouse my apartment has very poor sound isolation.

The preamp is basically the same as in Matchless DC30, it was ripped from a great amp built by Risto Kivioja. The phase inverter is from Vox AC-15, but with some resistor changes to match the lower headroom at the end stage, which is completely my own design. It uses 6AK6 tubes in push-pull configuration. I was unable to find any PP 6AK6 designs from the web, so this even may be the first such an amp in the world x)

I have to admit that in pentode mode, this is really too a loud amp during the nighttime, with its whopping 2-watt output stage. In triode mode, it becomes much quiter and now I can play with good distortion even during the night.

This amp works pretty damn well with guitar as well; about 90% of guitars of upcoming demo of our band were recorded through this.

Feature list

Philips 2858 (pics: finished build + original condition schematics)

I bought this amp from huuto.net, the Finnish version of eBay, in June 2003. It was covered by rust and had some blown up caps inside. I decided not even try to switch it on before rebuilding, so during the disassembly I draw the schematics of it.

Finally, in January 2004, I rebuilt the innards. Only original components are potentiometers, transformers and a choke. Everything else is brand new. I also aquired new tubes for it - it wasn't too easy...

This amp really doesn't sound like a 10-watt one. It is so damn loud that at least for me it is impossible to be in the same room with my Leslie speaker driven by this amp at maximum volume. I am really satisfied with the results; I got a great amp for a relatively low price.

Another rebuilding session took place in January 2009. I've learnt quite a lot about amp building during the last five years and now the amp will probably serve many years from now on. The basic idea was to provide two channels with minimal controls: channel one has just volume control, channel two also features a coupling capacitor switch, which acts as bass cut control. Channel one can be used with a synthesizer, channel two is brilliant for electric piano.

Radio amplifier (pics)

I built an amp from an old tube radio for Aku Rannila, who recorded a demo of our band, Pin Ion, and liked the 6AK6 amp (above) very much and asked me if I could build an amp for him as well. He had an old Philips tube radio lying around and it was used as the base.

ECC83 preamp is a mixture of Fender, Marshall and my own design. First stage has 2k85 cathode resistor, bridged with a 1 uF cap. After that there's volume and tone controls from Champ and the next stage is with 1k5 cathode resistor without cap. Output stage is an EL84.

I haven't heard this thing yet with a guitar, but even with the old, small speaker of the radio my Rhodes piano has never before sounded this good!

Tube preamp for Rhodes

I got some 230:6V transformers for very cheap and decided to find some use for them. Also I had one die-case aluminium box around, so I decided to do a preamp for my Rhodes Suitcase electric piano.

The preamp is basically exactly the same as Fender Champ preamp with one ECC83. It sounds like one, as well. If I need to get distorted sounds from my Rhodes, I just insert a Tube Screamer (check out later on this page) before this, and that's it. Power supply uses two transformers connected back-to-back. Works fine.

Tube Screamer TS-808 (pics)

I didn't have any distortion pedal, so I built a basic Tube Screamer clone. This was used together with the 6AK6 amp to get a good rock guitar sounds for our demo. Surprisingly, this sounds like a Tube Screamer :)

MXR Phase 90

I had a Boss Phaser for my Rhodes but I really wasn't too satisfied with it. I knew that many good Rhodes players used this specific pedal, so I decided to build one. Now I'm satisfied; this sounds much dirtier than the Boss.

Blue Magic overdrive

I don't know for sure but I've heard that this is a copy of a pretty famous Swedish boutique overdrive pedal. However, this one is a MOSFET driving a JFET to distortion, which sounds almost exactly like a tube triode distortion. This is a bit milder than the Screamer and does not have so much treble, but the basic sound is bit better to my ears.

Electro-Harmonix Pulsar (pics)

I built a EHX Pulsar tremolo for my Rhodes. I was a bit disappointed at first since it really sounds nothing like the Rhodes' own tremolo, but actually this is very usable unit. It's also possible to get really psychedelic sounds when driving the MXR EF (described next) from this.

MXR Envelope Filter (pics)

I was planning to build a EHX Small Clone chorus, but accidentally drilled the PCB of the MXR EF. Anyway, I built this one and it really rocks. Instant phunk when connected to Rhodes. Wish I had a Clavinet...

MXR Microamp

This was used to drive the Philips 2858 amp to distortion at bedroom levels. Now sits waiting for some use.

Orange Squeezer

I wanted to try to build a compressor pedal. So I did! A friend of mine uses this now.