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Old 12th March 2017, 12:50 PM   #1
bsk is offline bsk  United States
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Default Anyone Build Rod Elliot's Bass Guitar Amp (Project 152)?

Has anyone built this? Especially the EQ section. The EQ section reminds me of the SWR semi-parametric ones from the 90's.

Looking at ideas for my next preamp. I have never attempted an all SS one before.

Thanks.
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Old 19th March 2017, 11:58 PM   #2
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It concerns me a bit that Elliott complains about valves introducing additional noise and distortion, and more or less dismisses their use as a silly superstition by clueless musicians.

The bit about additional noise and distortion from valves is perfectly true, of course. But Elliott also manages to completely miss the point. The additional distortion is precisely what makes the valve a good thing, from the musician's point of view. The "excessive" distortion makes a bass guitar sound better, more interesting, more musical. The valve adds harmonics that are lacking from the instrument itself.

This certainly won't be the first time an electronics engineer has failed to understand the difference between Hi-Fi (accurate reproduction), and musical instrument amplification (where the goal is to create a desirable sound, not to accurately re-create a signal.)

But all this doesn't particularly make me think Elliott is the right engineer to design a musical instrument amplifier. If he thinks zero distortion sounds best, he certainly isn't the guy to design a bass amp for my tastes.

Elliott's bass amp is quite a complex project, too, so I would want to know for sure that it actually sounds good, before I started building it. It would be nice if there were a dozen clips on Youtube or Soundcloud or something.

-Gnobuddy
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Old 20th March 2017, 01:51 AM   #3
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For the sake of accuracy and completeness, this what you said;
Quote:
It concerns me a bit that Elliott complains about valves introducing additional noise and distortion, and more or less dismisses their use as a silly superstition by clueless musicians.
This is what Rod Elliott actually said;
Quote:
Valve (full or partial):
There is a great deal of nostalgia for valves ('tubes'), and many people think that the mere presence of a valve in a preamp gives it some characteristic that isn't possible with transistors or opamps. Mostly, this is untrue, and some amps that boast a 'valve preamp' simply have a token valve that achieves little or nothing other than greater noise and reduced reliability. Others may use the valve to (more or less) its full capabilities, but it remains a source of noise and unreliability. It is probable that few (if any) bass players would be able to pick a valve's presence in a preamp in a double-blind test, which makes it rather pointless.
Quote:
Valve (full or partial):
While still popular, high power valve amps are expensive, heavy, and comparatively unreliable. Hybrids (using valves and transistors) are also common, but if the valve stage is just at the front end (as a first gain stage) it's mostly a marketing exercise. Valve output stages need large output transformers and at least 4 (preferably more) output valves. These are only available from China or Eastern Europe, and quality is variable. Failures are common, and expecting more than 120W or so is generally unrealistic. This is rarely enough for bass.
Quote:
But all this doesn't particularly make me think Elliott is the right engineer to design a musical instrument amplifier. If he thinks zero distortion sounds best, he certainly isn't the guy to design a bass amp for my tastes.
Perhaps not, but one opinion only and only supported by conjecture.

You;
Quote:
Elliott's bass amp is quite a complex project, too, so I would want to know for sure that it actually sounds good, before I started building it.
What the amp includes;
Quote:
Input Gain - Can be switched between high and low gain from the front panel (or a footswitch, not shown in this design)
Tuner - Output for electronic tuning meter
Variable-Frequency Tone Controls - More-or-less conventional tone controls, but with variable turnover frequencies for both bass and treble
2-Band Parametric Equaliser - Variable frequency boost and cut controls that can be varied over the range 70Hz to 3kHz in 2 bands
High-Pass Filter - Set for 27Hz, it removes high-level very low frequency signals to improve clarity (switchable)
Effects Send/ Return - Dual phone jack sockets for external effects
Inbuilt DI - A balanced feed via XLR connector for a send to the FOH (front-of-house) PA system or recording console, variable
Compressor/ Limiter - A LED/LDR based adjustable limiter to maintain consistent output levels or prevent power amp clipping
Variable Crossover - An electronic crossover network (with defeat switch) so the signal can be split and sent to two separate power amps
Fixed Crossover - Another high pass electronic crossover set for 2kHz to drive a separate horn amplifier, no low-pass filter is needed
Power amp drivers, incorporating 'soft-clip' circuits
3 Power Amps - Two 300W amps (P68), plus a 60W amp (P27A is ideal) to drive the compression driver.
Quote:
It would be nice if there were a dozen clips on Youtube or Soundcloud or something.
Could you explain how a clip on YouTube or SoundCloud can give any indication of the sound quality of anything?
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Old 20th March 2017, 05:28 AM   #4
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I'm not sure what the kerfluffle is about, Elliott's website is available to anyone on the 'Net, anyone can read exactly what he said; I don't see the point of quoting bits of his website here.

That said, let's continue the exercise you started. This is what Rod Elliott actually said, straight off his website (I added the colour for emphasis):
Quote:
Originally Posted by Rod Elliott
Others may use the valve to (more or less) its full capabilities, but it remains a source of noise and unreliability. It is probable that few (if any) bass players would be able to pick (sic) a valve's presence in a preamp in a double-blind test, which makes it rather pointless.

<big snip>

When it (the valve) (i)'s operating non-linearly (but not clipping), there's still almost no difference, except distortion is higher
So, according to Rod Elliot:

  1. Adding a valve is pointless
  2. Few if any musicians could hear a difference
  3. The only things the valve actually adds are noise, distortion, and reduced reliability.
The context makes it clear that Elliott considers the additional distortion to be one of the negative qualities of the valve - it's listed along with all the other negative qualities.

Note also that there is no mention of even the possibility that additional valve distortion might produce any improvement to the sound. Either Elliott doesn't believe this to be the case, or he is ignorant on the issue, or it never occurred to him to mention it. In any case, as I said, he appears to have completely missed the entire point of using a valve in a (bass) guitar preamp.

Elliott also believes "few (if any)" musicians could hear a difference. That means he believes that most, if not all, of those who think the valve produces an improvement in sound are wrong, deluded, or lying.

Rather curiously, the claim that "few, if any" musicians could hear a difference, also implies that the additional distortion isn't actually a negative, because nobody can actually hear it anyway! But clearly he's speaking from the typical engineers viewpoint: additional distortion is bad, even if you can't actually hear it.

All this is pretty much exactly what I said in my previous post. So I don't really know what it was that upset you?

Quote:
Originally Posted by Tromperie
one opinion only.
Of course. I never said otherwise. In fact, I made it quite clear that it was my opinion only. Please re-read the following section of my previous post:
Quote:
Originally Posted by Gnobuddy
But all this doesn't particularly make me think Elliott is the right engineer to design a musical instrument amplifier. If he thinks zero distortion sounds best, he certainly isn't the guy to design a bass amp for my tastes.
See the words "me" and "my" there? I made it very clear that I was speaking for myself, and no-one else.

Quote:
Originally Posted by Tromperie
and only supported by conjecture.
Actually, supported by a lifetime of understanding the English language. My mother was an English Lit. college professor, and she taught me English starting as a baby. I read voraciously most of my life. I placed in the 99th percentile of the Verbal section of the Graduate Record Examination (GRE) back in my college days, meaning that, at the time, my reading and writing ability in the English language was in the top 1% of all college graduates - worldwide - who attempted that international exam that year.

The GRE is a requirement for admission to most graduate programs in the USA, and hundreds of thousands of students take that exam each year; as an example, almost 584,677 students took it in the year between July 2015 and June 2016, according to Educational Testing Services, who runs the exam. To place in the top 1 percentile that year, one would have to do better than 578,830 of the 584,677 students.

The number of examinees (July 2015 - June 2016) is listed on page 5 of this PDF published by ETS: https://www.ets.org/s/gre/pdf/snapsh..._data_2016.pdf

All this nit-picking is really not necessary; it does not take an extraordinary ability with the English language to understand what Elliott was saying. He (Elliott) was not being particularly subtle about his beliefs about valves in his write-up.

Quote:
Originally Posted by Tromperie
Could you explain how a clip on YouTube or SoundCloud can give any indication of the sound quality of anything?
Let's try the other side of that argument: could you explain how the lack of any online clips can give any indication of the sound quality of anything?

And how, in your opinion, is a complete lack of audio clips an improvement over having some high-quality clips available online to listen to?

Perhaps you are a fan of Elliott's, and that's fine. In a way, I am, too. I don't know the man myself, but I have a great deal of respect for the huge body of work he's created, and I applaud him for publishing it on his website. If I ever met him, I would thank him for the wonderful resource he's created for all those interested in DIY audio electronics. He did a wonderful thing.

But that doesn't mean I blindly and automatically think every one of Elliott's designs is a great one. In the case of this particular design, I personally find Elliott's publicly expressed opinions a matter of concern. Without audible evidence to convince me otherwise, I would not build this amp for myself.

All this is the same thing I said in my previous post, and I see no reason to change my opinion.

You, of course, are welcome to your own opinion, whether or not it agrees with my own.

-Gnobuddy
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Old 20th March 2017, 05:56 AM   #5
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Quote:
Originally Posted by bsk View Post
Has anyone built this? Especially the EQ section. The EQ section reminds me of the SWR semi-parametric ones from the 90's.

Looking at ideas for my next preamp. I have never attempted an all SS one before.
I've built a few bass preamps using Rod's guitar amp front end and also the Universal Mixer board. Both worked and measured very well and I played hundreds of gigs with them perfectly happily. I've since moved on to doing my own designs, but Rod's EQ scheme for the bass amp project is pretty standard "cookbook" stuff IMHO and it should work just fine. He does have that particular engineer's mindset that wants to optimize for low distortion and low noise, but I personally would prefer to shoot for about an order of magnitude more push in that direction, which I've pursued in my own more recent builds. I do build tube bass preamps occasionally too, but I have never really bonded with them all that much for my own playing situations, which are more jazz than rock oriented, and only use fretless instruments that already have all the harmonic content and general character I'd ever want, even unamplified. Vive la difference!
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Old 21st March 2017, 04:22 AM   #6
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Quote:
Actually, supported by a lifetime of understanding the English language. My mother was an English Lit. college professor, and she taught me English starting as a baby. I read voraciously most of my life. I placed in the 99th percentile of the Verbal section of the Graduate Record Examination (GRE) back in my college days, meaning that, at the time, my reading and writing ability in the English language was in the top 1% of all college graduates - worldwide - who attempted that international exam that year.
I would be embarrassed to post tripe such as this.

Quote:
Let's try the other side of that argument: could you explain how the lack of any online clips can give any indication of the sound quality of anything?
Perhaps your admiration of your English skills doesn't extend to answering a simple question? The point is, self-evidently, that a YouTube clip is an indication of the sound quality of your speakers.
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Old 21st March 2017, 05:09 AM   #7
JMFahey is offline JMFahey  Argentina
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Rod Elliott has a deserved reputation of designing properly woking no nonsense stuff, so even without building it, I alreadytrust it.

Tht said, it looks complex for a first design, IŽd build first the so called "guitar preamp", basically an SS version of classic Fender preamps and which in fact works quite well gor a MI preamp, even if usd with Bass.

Build and test one, youŽll like it.

then if you are comfortable, build ethe full featured one.

As of tubes, as used in most Bass preamps they donŽt do much.

Many are plain cathode followers which do nothing to sound, others are low gain stages, which again do little if anything at all, a few use them as distortion devices.

The real place where tubes shine is in overdriven power stages, but few choose that route for economic reasons.
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Old 23rd March 2017, 02:22 AM   #8
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Tromperie - have a nice day. I have better things to do.

-Gnobuddy
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Old 23rd March 2017, 02:36 AM   #9
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Quote:
I have better things to do.
So do I, except that I don't spend it slandering people who aren't around to refute baseless assertions. I have no personal feelings, positively or negatively, about Rod Elliott even though I bought and use several of his products.

I do, however, do regard slander as unacceptable.
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Old 23rd March 2017, 05:34 PM   #10
bsk is offline bsk  United States
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So a little more back ground - I have built several (more than 10) preamps for bass, mostly all tube, but a couple hybrid - tube front end with opamps for some tone control and output. I have implemented an all-tube Fdeck style HPF. Have also done one with an opamp. Both work great. (24db per octave F3 at 35Hz.) Current power amps are all based on Hypex modules - old guy trying to keep weight down. I am currently playing through a GB Fearful 15/6 (no tweeter).

I am a fretless player (5-string) trying to sound fretted (I just can't play frets - I am an old upright player). Keith Roscoe built my last two basses trying to get them to sound fretted and they works really well (absolutely love his necks).

So part of my goals at looking at different EQ controls is to be able to focus on my sound goals.

I did build a variable (freq) mid control similar to the EWS mid pedals and Traynor YBA300 mid control. It works pretty well - using an LM4562 opamp to do the dirty work. Any one tried this with tubes?

I was interested in Rod's design for the EQ, but just looking for practical experience with semi-parametric controls - mid controls in particular.

I have played through GK heads and the mid-controls do not line up well for me and my style. I know that these are not semi-parametric. Any others that I should look at schematics?

Just looking for ideas. Charlie has inspired me several times with his builds!
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