Building a "Hiwatt" tube Bass Amp

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Building a "Hiwatt" tube Bass Amp

I am interesting in building a "reverse engineered" (and perhaps improved) Hiwatt tube bass amp. I tried searching but i am new here so i don't really know what to search for, sorry if i make a mess.

I am interesting in building a replica hiwatt amp, about 2-300w'ish and perhaps with some modifications..

Has anyone here done something like this? I might be able to pay some money for drawings etc. but im not rich so, free would be preferable.

best regards, Per
 
That was very helpful, I like this forum already, I think i will try building the DR405 amp, I have never built anything like this before but I have built other electronic equipment and started a electronic related course some 10 years ago, most of the knowledge has probably left my mind but I think it will come back once i start building this monster. I do however need all the help i can get so dont be shy if you know something about this particular machine.

Best regards, Per
 
also, take a look here: http://mhuss.com/Hiwatt/tech2.html

the schemes are better,,,

btw, I'm a bass player and I would like a big power rig in the future when I'll stop building guitar stuff,,, I'm after a mean sound so I ain't that much oriented on tubes for my bass,,, I conceive bass as a percussion instrument if you know what I mean :D
so, maybe for my likes solid state is better, what you think? and how do you think this hiwat will sound? [better yet, what sound are you after with building this hiwatt?]
 
I like tubes, I don't know why really, just wan't to build something thats "vintage" and powerful. I'm not a bass player and I'm primarily building this to get into the electronic stuff again, later i will build a analog synthesizer and want something powerfull to connect it to, I just like to make sounds and I don't believe in rules, if it works then it works, even if it is a synth connected to a bass amp :D
 
Might be easier to do a known 300W bass amp like a 70's Ampeg SVT.

Parts are still floating around and take it from someone that owned one, hearing protection should be mandatory :D

I have never heard anything that had the kick I remember from that amp. I had it hooked up to a pair of 8 X 10" cabs. We were crazy back in the 70's. That was my Gig & Practice rig.:D

Edit, lots of Hiwatt schematics here schematic heaven

Many Ampegs are also on that site, Ampeg Schematics

Trout
 
I've been thinking about building a bass amp myself, maybe something like an Ampeg SVT with about 200w output. I've got an old monstrous Simms-Watts PA amp with 4xKT88s in UL that can be the donor for transformers (Partridge!), sockets etc. The power section can probably be kept as it is, I just need to build a new preamp when I have the time - and can afford the parts...
 
From my experience in my own personal bass rig:


For bass guitar rigs exactly the opposite approach is used from getting a good "real" guitar sound.


Use a preamp of some sort to get the sound you're after. This could be a tube head(even low powered, it doesn't matter) into a dummy load I use a Sansamp RBI. Then use this signal to drive a very large solid state power amp(1000 watts is a good place to start) into a very clean and uncolored cabinet(I use an Euphonic Audio NL-210 driven by a Crown MacroTech 1200 bridged into 8 ohms). I use this setup for mostly "classic" bass sounds with great results. What I found in the past was that a tube amp would sound great at a certain level, lower it didn't sound like an amp and higher it would break up a little too much. With this setup it sounds great quiet or loud. Is this what you're after?
 
When I played bass about 25 years ago, I built a tube preamp W/built in CCD chorus and SS compressor (for the sound). The tube preamp was dual channel, then ran into a stereo 15 band EQ with a footswitch to swap EQ channels. I could setup one channel for my J-bass and the other for my frettless P-bass. This all went into a couple of SS amps (biamp setup) to drive 2 EVM 15's in a ported cabinet, and a JBL horn (can't remember the model). What a great sound!

Just wish I would have taken a photo of it... long gone now.

Before that I used a Fender 400PS with 2 showman cabinets loaded with JBL's from early 70's. The 400 was all tube - sounded pretty good but took a forklift to move the thing! It had a 6L6 driving a transformer phase splitter then 6 6550's on the output! You could play and cook your dinner over the top vents!
BTW those top vents were always getting drinks spilled in them - hot 6550's don't like cold drinks.
 
Here's a pic of what my rig looks like, very compact which is something that you might not want but a great sound.

I do think the Hiwatt amp project could be a lot of fun. Maybe you could build something like a DR504 head and then use it as a preamp, I have one of those and it sounds great for bass.

DSCN0031.jpg
 
DaveMcLain said:
Use a preamp of some sort to get the sound you're after. This could be a tube head(even low powered, it doesn't matter) into a dummy load I use a Sansamp RBI. Then use this signal to drive a very large solid state power amp(1000 watts is a good place to start) into a very clean and uncolored cabinet


Exactly my thoughts really,,,
At the moment for reharsals I use a classic TNT115 [160w - all solid state] which has a 1x15 sheffield cone then use the hi/lo outputs to drive a 2x300 Novex PA with a 1x15 cab for the lows and a 1x12 marshall guitar cab for the highs,,, not exactly a monster but I can get a decent sound with my EMG 40DC and active eq onboard,,, plus the tnt has a decent preamp so it goes ok,,, this is what I share with the other bassists in the reharsal room,,, now, when I finishe building guitar preamps I want to build a cheap high power class d poweramp around 1000w then build a serious preamp [maybe tube maybe solid state we'll see] and then a decent speaker cab [4x10 should do the job,,,]

btw, are you running 1200 watts into a 2x10 cab???
 
I had a TNT combo a very long time ago, mine was the old 130 watter with a Black Widow. It really sounded pretty good, I've always liked Peavey's bass gear but it didn't have quite enough power.

After years of experimenting that's what I feel works best in most situations, preamp, high powered amp and a clean cabinet.

The Crown MacroTech 1200 is running bridged into 8 ohms so it puts out a little less than 1000 watts. John Dong at EA said that this is just fine, if it sounds good you're doing no harm, clean power being easier to handle than something that's distorted.

This is easily the best bass rig I've ever played much less owned, it was not cheap but the cost wasn't terrible either. Preamp $300, Power amp $450(both E-Bay buys preamp new, power amp used but in great condition), cabinet $900(they are expensive).

This rig really put out a great tone that's easy to use on stage. The low end is there but it's very clean. My old cabinet was probably louder(Ampeg 4x10 batmobile style) but it weighed about 140lbs and was twice the size of this cabinet! The NL-210 really is as light and compact as they say in the EA literature and it sounds fabulous. They also make a 4X10!

Previous rig: Ampeg SVP Preamp(sounded good but was very tough to keep working. Fixed several times). Ampeg SVP-1500 amp(sounded fine but blew up several times. Bought used and sold for purchase price 5 years later so not too bad). Batmobile cabinet(bought as a blem for a good price and sold for a good price. Worked and sounded ok but was very heavy and didn't sound so good on many stages, muddy low end).
 
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