organdonor amplification


Hello, I have an AO29 looking to convert to deluxe or 18 watt 6v6 lite. Do you have any info or can point me to some were I can find a wiring print or layout. Can the phoenix mod be completed on this model. The only worry I have read is the high voltage values that need to be tampered down. thanks mike

Asked By: Anonymous


May consider the 5E3 layouts too:

Search weber 6V6 layouts for more info.  Not sure if you can use the phoenix mod since only came across that mod using EL84s but probably so.

The Hammond AO-29 power transformer HT secondaries produce about 335-0-335 VAC depending on year model.  To lower B+ voltage and get 6V6 plate voltage in acceptable range, add a 10 watt 300 to 400 ohm ceramic power resistor in series after the tube or solid state rectifier  


Low wattage tube bass amp

Dear bassman857xx

Hi Steven, its no bother at all and those are excellent questions concerning the best use and sounds of the amp. This amp would suit your needs as you described and puts out about 15 watts. This would be plenty of power for home and practice use and tube amp wattage ratings are much louder. You may be able to play with a moderately loud band too especially if you mic’d the amp through a PA system. Also, if you needed more power, I can add a line out jack to run the amp signal out to a separate power amp. I would recommend a using a solid state plug in rectifier for use with bass for sharper attack, a bit more headroom and louder volume. Tube amps are the best sounding for musical instruments in my opinion. The dynamic reproduction of your instruments true tone is what sets them apart from solid state amps. The harder and louder you play will push the tubes into natural and musical overdrive. This circuit has a more robust power supply(higher value capacitors) that would be more suitable for bass guitar and linear tone and volume pots which also seem to work well with bass. In general tube amps designed for bass are usually much larger(more output tubes which means larger transformers) and have to put out three times the wattage of a guitar amp to push the low frequencies and still have enough clean headroom before being driven to distortion/overdrive. I would recommend a closed back 2-10 or 4-10 or 1-15 cabinet with Eminence delta speakers(that is what I use personally for bass drivers) handling up to 200 watts total so it will be very efficient. You can’t go wrong with Ampeg or Mesa Boogie bass cabs and they usually come stock with Eminence speakers. The total ohm speaker cab load would need to be 8 ohms to match the output transformer of this amp. Most cabs are 8 ohms. And later on if you decide to get a higher wattage amp that cab can handle it no problem. I hope this helps you and don’t mind passing along the information. Take care, Tim

- libband

Dear libband,

I hope you are having a great weekend so far. I am sorry to bother you but I really am a novice when it comes to amps. I just bought a pretty nice Jazz bass and plan on taking lessons and learning how to play. In my research for an amp I have come to the conclusion that a tube amp is the way to go. I do not plan on playing out in a band so I do not need anything big. Even though I say that, I still want to find a small unit that is capable of putting out enough sound just in case I change my mind. Could you please give my your opinion. For what it sounds like I want, do you think this amp would be a good option? Also, what kind of cab would I need to look for? Does it have to be a certain ohm? And last question…you have this listed as a guar/bass amp but not the others that you are currently selling. What makes this able to handle both interments while the others can not? I’m sorry for all the questions but I gotta do my homework. Thanks,

- bassman857xx
organdonor amplificationVarius Rufus custom tube guitar/bass amplifier15wattEL84organdonor amplificationVarius Rufus custom tube guitar/bass amplifier15wattEL84Item Id:281321898306End time:May-05-14 09:25:01 PDTSeller:libband (481)100.0% Positive FeedbackMember since Apr-19-04 in United StatesLocation: FL, United StatesListing Status:This message was sent while the listing was active.


i have my grandmas old hammond organ. I don't want to get rid of it but this is another way of enjoying it how much do you charge to build a guitar amp out of it? i love your work amazing stuff cheers.

Asked By: Anonymous


Hi, If you could tell me the model Hammond(L100 for example) or send a photo of the amp, then I can tell if its a good conversion amp.  Depending on which model it is, I can make it into a Fender tweed/6V6 tubes or a AC15/EL84 tubes guitar amp for 200.00.  For a bit more, it can be mounted in a solid wood head cab or a combo.  Happy to discuss options and thank you! 

Noise/buzzing/humming from tube amps

"If you’re experiencing a lot of noise coming from your tube amp, there are a number of things you should consider about tube amps that are different from solid state amplifiers.

First of all, it’s important to note that most tube amps are completely analog. Any analog circuit is going to carry noise. There are a few things that can interfere with the circuit and can cause noise such as florescent lights or dirty power. You need light to see, so this may be somewhat unavoidable. However, you can buy things like power conditioners to filter your power which will greatly reduce the noise carried into the amp via the A/C.

Another thing to think about is the interaction between your guitar and your amplifier. As stated before, analog circuits make noise. They have large transformers and other components inside. Now consider the pickups in your guitar. They’re magnets. When you walk up to your amplifier to change settings, you’re bringing the magnetic pickups closer to all those humming parts within your amp. By doing this, the pickups are going to “pick up” any noise those components are making. If the volume of your guitar is turned up, the noise is going to be amplified by the amplifier you’re plugged into. The type of pickup makes a difference as well. Humbuckers are designed to reduce the amount of noise that gets transferred to the amplifier by using two coils with opposite polarity. They aren’t perfect, but this essentially cancels out any noise that may come through. Single coil pickups, on the other hand, only have one coil, hence the name. These type of pickups are going to be much more sensitive to noise.

One last thing to consider is power and gain. If you have a 100 watt tube amp, it’s probably going to make more noise than a 15 watt tube amp. Also, if your amp is designed for high gain settings, it will most definitely make more noise than an amp designed to run cleaner. The higher you crank up the gain on your amp, the more noise it’s going to make. If you’re trying to turn up the volume, try turning down the gain and turning up the master volume. If you want more distortion and overdrive, then noise is an inherent part of obtaining that sound.”