DIY Class D/hybrid
I have been into diy guitar amps for a few years and I can't help but wonder how easy/hard it would be to build a bass amp. Now I know tube amps reasonably well but have never gone solid state. I do see that most bass amps are using Class D power sections, presumably to save on weight and pricey iron. So what would keep one from buying something like this and matching it with their (tube) preamp of choice to make an inexpensive hybrid?
Ebay has tons of them, but they all come from China so not sure about quality or reliability.
Thanks for your advice!
Class-D amps/power are simply a commodity. Power amps are simply a commodity.
All the tone comes from the pre-amp.
Build the best pre-amp you can. Pay attention to the output voltage so you can hook it up to any amplifier out there.
Get yourself a IcePower amp, SMPS, with a DSP to build into your cabinet.
DSP have limiters, and EQ which you won't get with a standard amp module.
There are USA built amp modules but they lack SMPS, and no limiter.
I built a 1000 watt hybrid B-15. The pre amp is a B-15 clone - 6SL7 tubes-(with a few slight mods). The power section is an ICEpower ASP1000. These modules are not sold to consumers but occasionally show up on ebay or CL. I can't say enough about the ICEpower module: self contained, plug and play, built like a tank, brutally powerful. My unit is 2U rack and weighs about 13 lbs. It is my go to amp. I might do some other mods to it and have a pro face plate made, at which time I will do a thread about the build with pictures and all.
There have also been several build threads on TB (some are linked in the Amps Forum FAQ sticky, along with many tube design reference links), and I've also seen a few more on Diyaudio.com and the Music Electronics Forum. Knocking off either Fender/Alembic or Ampeg front ends is a pretty popular approach, especially for first-timers. If you work up a schematic and post it here, there are plenty of qualified people to discuss it with.
I think I'm going to marry my beloved Eden WT-400 preamp with an ICE module just to lighten it up and perhaps get more headroom. There's some good info in this thread. Thanks fellas!
I'm curious how to achieve this as well.
I've never thought much about Plate Amplifiers for a bass rig.
Hey!! I ended up building my own sorta Frankenstein head. Not quite true DIY because I used a manufactured Pre-amp as well as an ICE module but here it is:
To me that is DIY. Taking apart existing gear and piecing the components together to fit a new need. With the costs of class-d amps, already built, with smps, and limiters, it makes no sense to try and build the amp part anymore.
Having said that, the pre-amp/signal processing has all the influence on the tone. The pre-amp signal processing is where the DIYer is going to find the most reward.
DIYer can do good these days ripping apart power amps, and even home theater gear and re-purposing it to musical instrument use. Good amp modules are showing up in many places.
When I resurrected a stripped Bassman 100 I got from a prison (they had been scavenging parts from it for years) I used Kevin O'Connor's preamp designs. I built an Ampeg type (B-15) with Baxandall bass and treble for the bass channel, and a modified Fender type (tuned an octave lower, with sensitivity/gain adjusment) for the Normal channel. Both plans came out of his book of projects, "Tonnes of Tone"...a really fun book.
They are both great, but I actually prefer the simpler Ampeg type channel.
I may do a project like the hybrid some day. DIY often does end up costing a lot more than intended.
I have a saying, "When you have more time than money, you usually end up wasting a lot of time, and spending too much money."
Hey gang, I am reviving this thread because I have lurned some things and scored a new project. Read on...
I saw the Fender TV series of Bassman amps, which by all accounts seem to be using Class D power supplies from the Rumble amps with a tube Pre. I thought it sounded like a great idea, but never did try the amps (they were overpriced before being discontinued).
Yesterday I scored a Rumble 350 off fleabay for $70 + ship. That's for the combo missing a speaker and a little cabinet damage, but it should make for a great project!
I would like nothing better than to use a tube preamp with the ICEpower module. One problem is that I don't quite know how to power it.
I looked seriously at the London bass pre listed here:
It's pretty steep for what it is, maybe $25 in parts and no power supply.
Anyway please fire off your suggestions! Thanks
In all honesty, I can't think of anything cheaper and tube-based that I'd actually want to use, but I'm not good at cheap and DIY in the same sentence. Please keep us posted though, I'd love to see what you come up with. I'll be posting a thread on my new DIY amp build in a few weeks, but I went with a SS preamp since I already have a pretty nice tube preamp for when I want that feel.
Maybe you could buy one of those cheap ART tube preamps (like this series) and mount it in your case? What format is the case going to be?
It would probably work, but For sure these low cost amp modules could never put out the kind of steady low end power that is required for bass. Those output inductors are probably 1/4 the size of the ones in most bass amps. This little amp is probably used in home hi-fi, home theater, computer speaker systems and is REALLY a 50W RMS amp at most, if it were rated truthfully. They are used because they are small, low cost and don't need much heatsink or ventilation.
No way of knowing how good the A>D section is, but probably good enough for bass.
You will need a REALLY good, fast regulated power supply that can provide large current surges without sagging, and a preamp, and then figure out how to cobble them all together without ground loops.
Fender has the Rumble 350 schematic here
It shows the IcePower module
Fender uses the power supply off the Ice for other circuitry.
If the amp is still working, then you can probably just build a pre-amp of your own and power it the same.
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