How about bass tube amp

[kldguitar]

About bass tube amp.
which company it?
what difficult to make it?
what tube used in bass amp commonly?
how many larger power commonly?
http://www.kldguitar.com

[mooreamps]

This is one of my projects that's on a back-burner right now. But, at some point I'm going to use my 813 project as a 200 watt bass amp. I'll also be using my new TMB tone stack along with the 6SL7's to support to low end.

-g

[Bruce / Mission Amps]

This is one of my projects that's on a back-burner right now. But, at some point I'm going to use my 813 project as a 200 watt bass amp. I'll also be using my new TMB tone stack along with the 6SL7's to support to low end.

-gI got the tip of my finger blown off with an amp running four 813s at 3000vdc. I hate them things and the ass who disengaged the safety switch form the RF deck cage.

[black_labb]

and i thought that my holden/wasp was high voltages with the 700vdc.

changed some caps to get more from the low end and it sounds great for bass. huge output tranny too.

[mooreamps]

Well, I wasn't going to run plate voltage quite that high, but diffently not a beginners project either. It will be interesting to get the feedback on this one to see what the bass players think of using such a big pair of output tubes in a rig like this.

-g

[black_labb]

sounds good. what are you using for the ot?

[Enzo]

I think we have wandered.

kld, there are several large tube bass amps.

The AMpeg SVT is still being made by Loud Technologies. 300 watts based on six 6550 tubes. They make several different SVT models, the SVT-CL is the all tube version.


Peavey used to make a 300 watt amp based on eight 6550s called the Classic 400. They have not made it in a long time, but the schematics can be requested from parts@peavey.com

Fender made the Bassman 300, 300 watts based on six 6550s.

You could make it based on other tubes than the 6550, but the 6550 is reliable and available everywhere, and in current production. And the voltages they use internally are not much higher than in guitar amps.

Many players like the amps, but they are extremely heavy because of the very large transformers. Most players do not want to carry an amp head that weighs 85 to 120 pounds. (40-55kg)

A large tube amp should not be more difficult to make except it will be larger, the chassis will need to withstand the weight. This is extra important during transportation. The SVT for example has two power transformers, one for the heaters, and one for everything else.

The power supply will have to be heavier duty, since the low frequencies will demand more from the filter caps.

[Steve Conner]

http://www.chambonino.com/construct/const9.html
http://www.chambonino.com/construct/const8.html
:eek: :eek: :eek:

[black_labb]

those are some huge amps, im curious about those el36 tubes. in the second one. seems like a cheapish high powered amp once you get a suitable transformer.

reguarding the original question, the difficulty with a bass amp is really just the higher power. the circuitry can be quite simple (there wont tend to be any effects, just the preamplifier, tonestack/volume and the output. the difficulty is getting big enough transformers to push enough clean power and have a good frequency response. that and the tubes are quite expensive. the power transformer will have to be quite bulky as well, as there tends to be higher voltage (depending on the tubes) and alot more current.

the reason they arent being made by as many people as valve guitar amps is the cost involved in the transformers. some people dont like carrying such a big amp around as well, but thats the consumers choice.

[mooreamps]

sounds good. what are you using for the ot?

Currently I have a 100 watt Hammond, thinking at first it was going to be an electric guitar amp. Yes, the chassis wieght on this one will be on the heavy side, mostly for not specing some of the parts correctly. Well, you live and learn.

But, I really did want to bring up a high power amplifier using this type of power tube. I realize doing a bass amp well is not an easy task to undertake. So, I'll take whatever feedback I get off of this first one, and then work those issues as they present themselves.


-g

[black_labb]

cool, im thinking of doing a 100w amp with tremolo/vibrato (fender made me get mixed up, the one where the volume fluctuates).

i think that a throbbing distorted bass would be really cool. would be a good head for guitar too.

[David Schwab]

I think we have wandered.

kld, there are several large tube bass amps.

The AMpeg SVT is still being made by Loud Technologies. 300 watts based on six 6550 tubes. They make several different SVT models, the SVT-CL is the all tube version....

Don't forget Mesa!

I have a Mesa Boogie Bass 400+ (http://www.mesaboogie.com/Product_Info/Bass_Amps/Bass_400_/bass_400_.html), 500 Watts! 12x6L6, 4x12AX7

And yeah, it's too damn heavy, so I don't really use it anymore.

It's a much nicer amp than an Ampeg, which have awful tone stacks IMO.

[Enzo]

Yep forgot that one. List wasn't meant to be all of them, just examples

[Gtr_tech]

I think we have wandered.

kld, there are several large tube bass amps.

The AMpeg SVT is still being made by Loud Technologies. 300 watts based on six 6550 tubes. They make several different SVT models, the SVT-CL is the all tube version.


Peavey used to make a 300 watt amp based on eight 6550s called the Classic 400. They have not made it in a long time, but the schematics can be requested from parts@peavey.com

Fender made the Bassman 300, 300 watts based on six 6550s.



Don't forget the Fender 400PS. Rich Koerner swears by those. The Traynor Super Custom Special (6KG6s) is nothin' to sneeze at either.

[Steve Conner]

While we're wandering, did anyone else notice that a 100 watt Hammond OT is completely wrong for a pair of 813s? :(

If you run it at its intended B+ and impedance match, you'll only get 100 watts. The 813s need at least 1500, maybe 2000 or 2500V to get them raging. In this case, the output transformer will start to saturate below something like 200Hz, since it's having to eat so much more voltage than it was designed for. I predict it will sound like crap, and arc over and catch fire within a few minutes.

If you really want to take advantage of these tubes, you need a 20lb custom OT, a plate transformer salvaged from some ham radio boat anchor, a wall of 4x12"s and no neighbours :)

[mooreamps]

Really ? Ya well, thats nice..... However, I've already brought up beam power on these tubes up to about 120 milliamperes per tube and ah, no problems yet. It's also the project which I developed the current transformer, which is what I use to filter the filament power supply. A "current" transformer is a device which operates in the current domain, verses the voltage domain, and allows to shunt the 120 cycle ripple current ; to ground. It's the device that allows me to filter the ripple voltage on the filament power supply which provides the 10 volts at 5 amperes for the tube filaments, and yet only dissipates a few watts as waste heat across the primary winding. . . . But all of this is the least of my concerns for a bass amp.

-g

[Steve Conner]

Yes, it'll work just fine, as long as you don't try to push the power much above 100 watts.

[mooreamps]

Yes, it'll work just fine, as long as you don't try to push the power much above 100 watts.


I actually will push the output power much above 100 watts. The plate dissipation for each 813 is rated @ 125W. These tubes running class C in a radio frequency transmitter are run up to 300 Watts PEP. It won't hurt the output transformer either, as they are High Potted at 2 KV at the factory.

-g

[kg]

gary, i think steve is pointing out that high power, high plate voltage tubes "like" higher plate load impedances, which is correct.

i'd also like to point out the baga: (http://ken-gilbert.com/the-big-ass-guitar-amplifier) 12x kt90s, 4x el84, 1x 6n1p, 100lbs, 500w. 9 years later on the same kt90s!

[mooreamps]

gary, i think steve is pointing out that high power, high plate voltage tubes "like" higher plate load impedances, which is correct.

i'd also like to point out the baga: (http://ken-gilbert.com/the-big-ass-guitar-amplifier) 12x kt90s, 4x el84, 1x 6n1p, 100lbs, 500w. 9 years later on the same kt90s!


This I do understand. In fact, I was intending to run both of these tubes in triode mode just for that very same reason, and counting on the common-mode rejection of running them in push-pull for power supply hum rejection, not because of a few volts of ripple on the plates, but the few volts of ripple on the screens.

I'm just guessing, I'd need a quad tube VVR type circuit if I wanted to add electronic power scaling for a power amp using this scale of high voltage.
Also, unbeknown to Kevin, I have already abated the in-rush current problem with using this type of circuit. I tried to explain last time I talked to him, but perhaps another time.

-g

[mac1amps]

I have to admit that it AMAZES me just how LAME sounding the Mesa 400 series sounds for bass. Even with a 12-tube output network (the 400+) they still have an extremely "farty" sounding low end that doesn't compare to a classic 70's SVT. The OT is about the size of a Fender Twin's, so I'm sure an OT upgrade would help....Mesa should stick with guitar amps.

[David Schwab]

I have to admit that it AMAZES me just how LAME sounding the Mesa 400 series sounds for bass. Even with a 12-tube output network (the 400+) they still have an extremely "farty" sounding low end that doesn't compare to a classic 70's SVT. The OT is about the size of a Fender Twin's, so I'm sure an OT upgrade would help....Mesa should stick with guitar amps.

Mine isn't like that at all. I didn't get an SVT because they color the tone of the bass so much. The 400+ is very smooth and clean.

When I first got it I also had a GK-800RB, and the Mesa was just as clean, but didn't have as much power with the single 4X10 cab as the GK.

I absolutely hate SVT's, and Ampeg's in general. My 60's B-15n was nice, but not useable for gigs. And rather boxy sounding. But the rest have dreadful preamps and tone controls, even the SS amps. They went out of business for a reason!

[jbrew73]

i built an amp with an ampeg pre in one channel and fender in the other. the power amp was basically an amp b15. i favored the ampeg pre over the fender. i know a lot bass amp designs use a fender style t/s and im interested in a mesa 400 amp but worried i wont like the preamp. id like to hear more opinions on the fender/ampeg debate.

[black_labb]

I have to admit that it AMAZES me just how LAME sounding the Mesa 400 series sounds for bass. Even with a 12-tube output network (the 400+) they still have an extremely "farty" sounding low end that doesn't compare to a classic 70's SVT. The OT is about the size of a Fender Twin's, so I'm sure an OT upgrade would help....Mesa should stick with guitar amps.

im not sure, but could it be that you were maybe pushing too much low end into the speakers, and they were farting?

no experience with 400+, or svt's but from what ive heard they sound like they wouldnt be farting.

[mac1amps]

'having always despised the sound of a "farty" bass response. I never run a Bass control beyond 3 or 4, depending on the overall volume level ("4" is even too high for many amps). In the case of a classic SVT, I'll even [slightly] "cut" the bass control (from its "flat" setting). Another factor is also the instrument being used. FWIW, I'm predominately a Fender Bass kinda guy. In the case of something, like say, a Gibson EBO....well, there's not too many amps that WOULDN'T sound farty with one of those (but I guess some cats like that sound........Jack Bruce anyone?)

[David Schwab]

'having always despised the sound of a "farty" bass response. I never run a Bass control beyond 3 or 4, depending on the overall volume level ("4" is even too high for many amps). In the case of a classic SVT, I'll even [slightly] "cut" the bass control (from its "flat" setting). Another factor is also the instrument being used. FWIW, I'm predominately a Fender Bass kinda guy. In the case of something, like say, a Gibson EBO....well, there's not too many amps that WOULDN'T sound farty with one of those (but I guess some cats like that sound........Jack Bruce anyone?)

Jack Bruce's tone was a wall of distortion... that was Marshall amps on 10. Then you take Felix Pappalardi, who used a very similar tone, and that was mostly from Sunn amps.

I've run my Mesa was the bass over 5, probably around 8, and I didn't have a farty tone at all. It might have been your speakers, or you were running the amp at the wrong impedance. I was using mine with an EMG P/J setup. You need to watch the input volume, because without using two cabs, you don't get the full power, and like any tube amp, it will distort.

But I played mine at outdoor shows a bunch of times with only the 1 4X10 Mesa/Eden cab, and I didn't have any farts happening. And I play loud, and with a lot of lows and low mids.

And I love Bruce's tone. ;) I had the first Peavey bass amp (400 series "the Bass") and it had a great distortion circuit... got that punchy burp just like Jack. But it was switchable, so I wasn't stuck with it.

Thing I hate about SVT's is you instantly lose the tone of your bass. Especially with the Ultra Lo on, you get that horrid hollowish crap tone. All the presence and punch is gone, and there's no way to set the preamp flat so that it doesn't step all over your tone.

I'd take a Sunn Colosseum or Acoustic 360 amp any day over an SVT.

Audio examples of SVT tone mangling:

Direct (http://www.sgd-lutherie.com/media/new_bridge_test_5_direct.mp3)

SVT "Flat" (http://www.sgd-lutherie.com/media/new_bridge_test_5_svt_flat.mp3)

SVT "Rock" (http://www.sgd-lutherie.com/media/new_bridge_test_5_rock_svt.mp3)

These are via the Ampeg SVX plugin, but they sound just like the real thing.

[Steve Conner]

Well, you need to define what you mean by "farty". I take it to mean an overdriven bass sound with lots of harmonic distortion going on. This can actually be a very useful tone for recording. If it weren't for the harmonics, listeners with small speakers probably wouldn't hear your low notes at all.

I also found a little bit of overdrive good for my stage sound. By emphasizing the pick attacks, and making the low notes more audible, it helped me tell if I was playing in time and in tune.

However, in my experience, sound guys hate it because they see it as the bass player trying to step out of the frequency range where he belongs. Out of all the gigs I've done, the sound guy only mic'd my amp once, the rest of them just DI the bass.

Some speakers fart even with a clean amp. High efficiency speakers, like guitar 12s and the 10s in the original SVT cabinet, generate a lot of bass harmonic distortion when you drive them hard. But you also get other designs that can put out a lot of clean, deep bass. If you use a modern 4x10 with properly tuned ports and long-excursion woofers, any farting is probably coming from your amp. Especially since a cabinet like that would be less efficient than an old-school fart box, so the amp has to work harder.

[Alex/Tubewonder]

This thread is pretty perplexing. Original poster is a Chinese amp factory and you guys are enthusiastically showing off how much you know and provide info. Even more perplexing to me is that some of the respondents are known to be extremely protective of their trade secrets. Free consultations to a Chinese amp factory, my, my....

[David Schwab]

This thread is pretty perplexing. Original poster is a Chinese amp factory and you guys are enthusiastically showing off how much you know and provide info. Even more perplexing to me is that some of the respondents are known to be extremely protective of their trade secrets. Free consultations to a Chinese amp factory, my, my....

It's only common knowledge, and if they can't figure that out on their own, they aren't going to make a good product. Who's giving out trade secrets? I didn't see any.

I mean they can just go and buy a SVT and copy it...

There are a LOT of tube amps for bass these days.

[David Schwab]

Well, you need to define what you mean by "farty". I take it to mean an overdriven bass sound with lots of harmonic distortion going on. This can actually be a very useful tone for recording. If it weren't for the harmonics, listeners with small speakers probably wouldn't hear your low notes at all.

I also found a little bit of overdrive good for my stage sound. By emphasizing the pick attacks, and making the low notes more audible, it helped me tell if I was playing in time and in tune.

However, in my experience, sound guys hate it because they see it as the bass player trying to step out of the frequency range where he belongs. Out of all the gigs I've done, the sound guy only mic'd my amp once, the rest of them just DI the bass.

Some speakers fart even with a clean amp. High efficiency speakers, like guitar 12s and the 10s in the original SVT cabinet, generate a lot of bass harmonic distortion when you drive them hard. But you also get other designs that can put out a lot of clean, deep bass. If you use a modern 4x10 with properly tuned ports and long-excursion woofers, any farting is probably coming from your amp. Especially since a cabinet like that would be less efficient than an old-school fart box, so the amp has to work harder.

Sound guys hate when the bass is loud enough to be heard over the PA system. Then they lose control over the mix. But if you let them handle your sound, you won't ever be heard over the kick drum, and your sound wont be your sound! If you play at normal stage volume, you wont get in the house mix at all... which sucks if you are recording the show. I once overheard a sound guy saying that he hated the a bass players tone, who was getting a Jacoesk burp.. he said "I hate that type of tone" so he made it sound totally different out front.. and you pretty much couldn't hear the bass!

There are many great sound men, but lots of tone deaf stupid ones that need to go back to taking orders for fries and burgers. They spend way too much time on the drums, and then the drums don't fit into the mix anyway. They are as bad as the idiot directors/camera men that film live concerts and show a close up of the guitar players PICKING HAND during a solo! Or that old clip of the Who doing My Generation where they showed a close up of Pete, who was doing nothing, while John was doing his solo!

Every band needs their own sound guy or gal.

Getting back to bass amps... yeah a little overdrive is great. Gives you harmonics and a nice burp on your bridge pickup. The SVT is way outdated and overrated. It was supposed to be this massive amp, but at 300 Watts it hardly keeps up with my 150 Watt Trace Elliot combo amp without massive distortion (1X10 in a bandpass box with a 100 Watt Fostex tweeter!). They have a chance to make good hybrid amps, but they cling to that awful preamp design.

People seem to forget how things were in the 70's, or they are too young to know. People did not love Ampegs. Guitar players hated the things. They were too clean! Everett Hull (founder of Ampeg) hated loud rock music. It wasn't until his passing that they made any kind of amps people wanted to use... except the small bass amps like the B-15 and stuff. Those were nice amps.

Bass amps sucked in general until the solid state models came along... That's why you saw so many Acoustic 360's and Sunn Colosseums. Those were loud clean amps. After battling with underpowered crap like Fender Bandmasters, Ampeg V4B's, and Guild Thunderbasses, the first loud clean amp I had was my Peavy Bass 400 series. Big stinkin' 2X15" cab! I see one of those heads in a local shop here for $150.. I'm real tempted to go nab it!

Anyway... yeah modern speakers don't break up, unless they want them to. You can't get my Mesa/Eden cab to flinch. I used that with my GK-800RB and as an extension to the Trace, and it's clean as a whistle. It also weighs a ton. The tweeter blew out a long time ago before I got it, but otherwise it sounds great.

The only way to get a 400+ to fart is turn the preamp gain up and master down on purpose, and even then I could not get any Jack Bruce style fuzz*, or run it into an underrated cab of the wrong impedance... thus making the amp only about 100 Watts. It's way louder and cleaner than an all tube Ampeg.

(*another thing about Jack Bruce was he had a diode clipping circuit in his bass.)