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Messages - Psycho Bass Guy

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2161
Bass Amps & Effects / Re: When Acoustic amps ruled the world...
« on: February 22, 2010, 07:49:30 AM »
Acoustic morphed into SWR, Eden and later, Thunderfunk. Lifted from TB:

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Over 20 years ago, Russ Allee, who designed the 360 and 370 amps for Acoustic left that company and started a new company called Amplified Music Products with a guy named Roger Smith. Russ had Steve Rabe, another ex-Acoustic guy, help design the preamp for the AMP 420 amplifier heads. The preamp section had an “enhance” switch, fixed frequency bass and treble knobs and four semi-parametric midrange bands. The amplifier also had a variable limiter and a crossover for biamping if you had another power amp. AMP also made a lower wattage version called the 260.

Steve Rabe left AMP at some point and founded SWR. He was across the street from Groove Tubes and designed the bass preamp that Groove Tubes used to sell. The GT preamp was identical to the front end of an SWR studio 220, just no power section. SWR’s studio 220 and SM-400 were designed by Steve and were pretty similar to the old AMP design except they used a 12AX-7 tube in the input gain stage, and the enhance switch was replaced with a variable “aural enhancer” knob.

Deciding that he wanted to offer cabinets as well as amplifiers, Rabe commissioned David Nordschow of Eden Electronics to make speaker cabinets for SWR. Up to that point Eden had been making PA speakers. Depending upon who you listen to, the development of the original goliath 4x10 + tweeter cabinet has a couple of versions. Eden claims that SWR wanted a two way cabinet (presumably a 15+horn) and David sent SWR the 410T as an afterthought, wanting to know what they thought of it. The other story is that Steve Rabe and David Nordschow collaborated on the design. In any event, Eden made cabinets for SWR for a while until SWR opted to make its own, presumably due to quality control concerns. The split was not entirely peaceful, but wasn’t quite up to the soap opera status of the rift between Nick Epifani and Jim Bergantino. After many years, Steve Rabe left SWR to found Raven labs, and subsequently retired.

Eden improved its quality control, and continued to make cabinets under its own name. Wanting to offer a complete line David released a couple of heads with a preamp designed by James Demeter. The Preamp was very similar to the VTBP-201, with the addition of a DBX-style two knob compressor. Later, David revamped the Eden amp line with the introduction of the “world tour” series, with a preamp designed by none other than Russ Allee. The front of the world tour series amps was very similar to the AMP-420 and SWR studio 220. There were only 3 semi parametric bands, and the compressor was a simple on/off switch. There was a variable “enhance” knob, but a crossover was offered only on the WT-800. Like the SWR, the Eden incorporated a 12AX-7 preamp tube, another departure from the all solid state design of the AMP-420.

Why was Allee available to consult for Eden? Well, AMP folded in 1988 and was reportedly bought by Gibson. Either Russ Allee designed the GB-440 for Gibson or Gibson just continued making the AMP-420 under the new Gibson GB-440 moniker. Rumor has it that Gibson made some changes that destroyed the reliability of the amplifier. (Imagine Gibson doing that to any company they’ve bought out).  Production of the GB-440 was halted sometime around 1990 and the unbuilt amplifiers remained in a warehouse for some time.


I have an AMP preamp and two Gibson GB-410 cabs, and that's about the extent of my "Acoustic-related" products. Around here, what few vintage Acoustic amps I run across are beat-to-death junk or "case classics" amps that look pristine because they never worked.

2162
Gibson Basses / Re: Way overpriced one-off smart wood les paul bass off to ze Reich!!!
« on: February 22, 2010, 05:44:32 AM »
Some of my criticisms of similar versions of the bass (90's LP Studio's) were less than charitable. I sincerely hope Uwe's is contrary to my experience with them.

2163
The Bass Zone / Re: Anyone use Ampeg SVX software?
« on: February 21, 2010, 06:19:40 AM »
Found this: http://www.ikmultimedia.com/ampegsvx/download/

I'll let you guys know.


2164
Bass Amps & Effects / Re: 15" tone rings
« on: February 20, 2010, 09:31:52 PM »
Sniper,
 I'm going to address the conversation that you quoted first, then your actual post. I don't disagree with the conclusion in regards to the Super Twin, but there's a whole lot of BS in between about UL in general. Maybe I'm just missing the context, but for the sake of argument:

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Many people in the guitar amp world mistakenly refer to the Fender tapped screen circuit as an Ultralinear design. It is not, and the taps were not intended, nor are they capable of producing Ultralinear operation. Typical Ultralinear operation for 6L6 class tubes requires a 43% tap (based on turns ratio), which is about what the Hammond transformer provides at 40%. True Ultralinear operation results in much lower distortion, and much lower power output -- about 35 watts is the absolute maximum RMS power output that a pair of 6L6s can give in an Ultralinear design.

I don't know where this person is getting their info, but UL output results in MORE, not less power; that's the whole purpose of the design; you hold the screen current down while jacking up its voltage, resulting in larger current swings from cathode to plate, which equals more power. The biggest problem with UL is that the high screen voltage can arc in cheap tubes and you need more drive power to push them, which is usually accomplished with a cathode follower drive stage. Strictly speaking for the Super Twin, this is correct because the rest of the circuit, but this is presented as general info, and there are OTHER Fender amps that are UL with 6L6's, and certainly well above 35 watts per pair: ie- the Bassman 135.

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Therefore, when using the tapped version of the 1650T in the Super Twin, the amp would not produce much more than about 110 watts continuous RMS output. For this transformer to work to it's best ability, the screen taps would need to be taped off, and then have a standard choke type filter system installed for the screen B+ take off. Under these conditions (strict pentode operation),

Someone is talking our of their ass: 6L6's are beam tetrodes, not pentodes, and they have a different transfer curve, bias point, and higher output power because of it. There is no common audio pentode equivalent to the 6L6GC; the closest is the EL34, a much higher powered tube which is almost impossible to confuse with a 6L6GC.

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As for the actual design of the Fender tapped screen circuit, the purpose of these taps was a cost saving measure on Fender's part, in that they eliminated the need for the choke to provide adequate filtering for the output stage. That was it, and nothing more. This is not an opinion, but a fact that came out of a conversation I had with the circuit's designer.

Is this guy seriously trying to say that a transformer choke is cheaper than a cap or that you can't have UL without a choke? There are plenty of UL amps that don't have a choke; I have a few of them.

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Finally, contrary to what was claimed, the Super Twin is quite capable of putting out 200 watts continuous RMS -- if the P-P impedance is correct to allow for it. In this case, the original Super Twin transformer has a P-P impedance of 1500 ohms, which is proper for six 6L6s in Fender's tapped screen design. This is why the Hammond transformer, as a 1900 ohm unit, will not allow full power output to be produced even without screen tapped operation

...even though he earlier said that UL tapped screens produce less power???

Quote from: sniper dog on February 19, 2010, 11:13:25 AM
Taking this into consideration, it might be best to investigate as to whether the OPT in a Twin 2 (which uses a choke) would be able to put out 100 watts driven by two KT88's as it shows 465V before the choke and 460V after the choke on B+ on the Twin 2 schemo. It might be a little marginal on the 88's? It would certainly drive them at a lower output and that would give it some reserve on "depth" or reserve current which is what a person would want in a bass rig. I would guess and venture about 75 watts RMS and about 150 peak or program burst. I would prolly gain a bit on the simplified preamp as far as reserve also."

As I alluded earlier, you could add a cathode follower for the drop in your forward gain, giving you greater current headroom and drive. That's also awful low voltage for KT88's. They run comfortably in the 6-700 volt range, and the higher you can get them, the cleaner they will run. The SVT's drive stage works this way with each side of the inverter feeding a 12BH7 (basically a higher power 12AU7) as a cathode follower, basically a power amp as opposed to a strictly voltage gain stage, to drive the output tubes.


2165
The Bass Zone / Re: Anyone use Ampeg SVX software?
« on: February 19, 2010, 02:12:27 PM »
..not the latest version. I did try an early "freebie" download a few years ago that inserts random noise in your tracks unless you actually buy the program, but it was a pre-release beta. If you know of a new demo version, post the link, and I'll give it an honest assessment.

2166
The Bass Zone / Re: Anyone use Ampeg SVX software?
« on: February 19, 2010, 01:08:37 AM »
To be a completely cocky ass, I know way more about mic technique than most of these software emulations do about tone.  :mrgreen: :o ...but I digress.  ;)  In all seriousness, I truly have never encountered an emulation that could equal the tones I have recorded using minimal equipment.

Like I said before, I do not dispute that they are valuable tools, but getting a good tone with a real amp is nowhere near as hard as some would make it out to be, and as far as afternoon playing, my SVT sits on the Acme and an Auralex Gramma in my den next to the B-15. None of my neighbors have ever complained, and I play at all hours of the night.

2167
Gibson Basses / Re: Gibson Facing Price-Fixing Lawsuits
« on: February 18, 2010, 10:54:59 PM »
Quote from: Dave W on February 18, 2010, 06:47:31 PM
I don't trust that reporter to know what he's talking about.

FYI, we are both employed by the same company, Gannett. You are wise.

2168
The Outpost Cafe / Re: What if Journey and Metallica....
« on: February 18, 2010, 10:52:30 PM »
I LOVE Danzig!!! I saw the Shakira parody a few years ago when it first came out, but never thought to post it here. The best part is that the guitar mashups are actually real Misfits songs.

2169
Gibson Basses / Re: Really cool rare Epi les paul standard bass,
« on: February 18, 2010, 12:03:31 PM »
I left it alone for two reasons: 1-it's not really what I'm looking for and 2- not ten seconds after I put up a post here expressing my interest, a bid was placed, so hopefully, it went to fellow OP'er.

2170
Gibson Basses / Re: Really cool rare Epi les paul standard bass,
« on: February 18, 2010, 06:50:59 AM »
Anyone interested in this one? I may make a go of it since I have some old Ibanez Musician p/u's that should fit it.

2171
The Bass Zone / Re: Anyone use Ampeg SVX software?
« on: February 18, 2010, 06:24:23 AM »
FWIW, a really good way to tame the volume of an SVT without losing its tone or using a dangerous "soak" device is to use a very ineffcient cab.  I have an Acme series 1 4x10 that fulfills this purpose quite well. With a little tweaking of the crossover attenuators on the cab, it does a very good impression of the 8x10.

2172
Bass Amps & Effects / Re: 15" tone rings
« on: February 18, 2010, 12:03:53 AM »
I'd drop the input cathode resistor, ditch the second 12AX7, and use a 12AU7 or even a 12BH7 for the tone stack. You'll have to recompute the r/c tone curves to the lower plate resistance of the 12AU7 (roughly 1/10th the 12AX7's) if you want the same frequency values, but I think you'll find that it will be a much bass-friendlier preamp just by changing the tubes and little else. It'll still sound like a Fender, but it will be more like a 400PS than a Showman.

  You also won't necessarily overpower the circuit by not having an additional channel; your PT will just run cooler from less current demand, which means you can get a little more out of its other voltages without stressing it.

2173
The Bass Zone / Re: Anyone use Ampeg SVX software?
« on: February 17, 2010, 11:34:55 PM »
Quote from: Deathshead on February 17, 2010, 09:09:29 PM
Anyone using the ampeg svx software to practice and mess around with?

If you havent tried it, it will really blow you away.

...being the proud owner of several real Ampegs, among a host of amps, (though none modelled by SVX) and having used Amplitube (their first amp modelling product) extensively, I highly doubt it.

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I run my basses thru a line 6 toneport ux,
pick the SVT-8x10 combo,
all knobs turned to 2 o'clock, freq on 1=awsome tone.

You, my friend, need to try the real thing.  Most of the little whiz-bang modellers, pedals, and emulators sound great... until you find an accurate point of comparison. I'm not saying they're not useful tools, but as far as the SVT, there is NO substitute.

2174
Other Bass Brands / Re: Cort Action Bass?
« on: February 17, 2010, 11:21:15 PM »
Having played both, the Dean is a superior instrument.

2175
Gibson Basses / Re: way overpriced one-off smart wood les paul bass.
« on: February 17, 2010, 07:45:45 PM »
Quote from: uwe on February 17, 2010, 05:17:37 PM
I agree with everything you wrote about the Barts. I wonder if they sound any better without the TCT active circuit?

I doubt it.  My G&L (another company whose bass sound is normally very pickup-defined) L5500 which has EMG's (another 'neutral sounding' pickup) and a similar preamp, sounds great, but it doesn't sound like any other G&L. The Bart equipped Les Pauls just sound bad. I guess you could compress the crap outta them in the studio for a psuedo-Ken Smith tone, but it's a crying shame to take such a naturally raucous instrument and for all intents and purposes, neuter its sound.  The Designing Women picture is an apt comparison.

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