Dear All.
I'm in the paper design stage of a bass guitar preamp.
In the middle of the thing I want to put an equaliser. And as I am into valves, I want to build a valve one.
I've found this diagram, http://www.jogis-roehrenbude.de/Verstaerker/Equalizer.htm
I've modelled the main elements, and they seem to work well.
What I'm after are any insights regarding the frequencies for the equaliser. Having sniffed round various guitar shops, it seems that the options are many and various.
I have seen them with starting frequencies as low as 32hz, then they double, [octave] up to about 10k. Others are 50/100/200 etc., and ones with bigger gaps.
Any thought would be most gratefully received.
Kind regards
Bill
I'm in the paper design stage of a bass guitar preamp.
In the middle of the thing I want to put an equaliser. And as I am into valves, I want to build a valve one.
I've found this diagram, http://www.jogis-roehrenbude.de/Verstaerker/Equalizer.htm
I've modelled the main elements, and they seem to work well.
What I'm after are any insights regarding the frequencies for the equaliser. Having sniffed round various guitar shops, it seems that the options are many and various.
I have seen them with starting frequencies as low as 32hz, then they double, [octave] up to about 10k. Others are 50/100/200 etc., and ones with bigger gaps.
Any thought would be most gratefully received.
Kind regards
Bill
billr said:
Borrow ideas from commercial gear, then blend for your taste.
http://www.bassandbeyond.net/products.html
In my bass rig I use a SansAmp RBI for a preamp(solid state) and it doesn't have parametric EQ but in the past I have used other preamps that did(Peavey Ampeg SVP Pro and a few others). Having it is a nice feature since it allows you to put a notch or hump in the frequency response curve and then move it around to find a "sweet spot" very easily and quickly. I would say however that if the frequency bands are chosen carefully and they happen to work well with your bass that something with standard EQ like the Sansamp would work just fine too.
billr said:
I don't believe! I like it for the convenience. As well as my friend John Pursel likes it:
http://www.youtube.com/watch?v=_U3pKSu1BU0
OK guys, calm down.
I know Anatoliy and enjoy his Eastern European perspective but I can also see how it could seem abrupt and short to those who don't know him so well. His wisdom is great.
Please give each other the benefit of the doubt and try see what the other poster was trying to say (not necessarily the literal meaning of the words) before firing back rebuttals.
billr said:
I honestly answered you: "because I like it's convenience". When you are on a stage, or on a gig, you are short of time, right? Second, while graphics EQs are great to shape mic-to-speaker response flat, they are less convenient to shape sounds of bass guitar and are more complex to design and to produce. However, some manufacturers of bass guitar rigs implement graphics EQs, but they are very different from conventional graphics EQs: instead of steady rows of 1/3 or 1/64 octave filters they use less of them, but tuned on certain frequencies more usable to shape bass guitar sounds. While some bass guitar players may be satisfied by choice of frequencies manufacturers give them, but some want more freedom, so they prefer parametric EQs. If you would go and examine rigs that manufacturers offer to professional bassists, as I recommended you from the beginning, you would find all this answers. They are not just theoretical thoughts of beginners ("I was interested why you thought that", as you write), they are results of knowledge and experience, trials and errors, and of successes.
billr said:
First off don't listen to those who are telling you to build a Fender style tone stack. A tube bases equalizer would be great. Also that tone stack has a huge insertion loss and you need a full 12AX valve just to recover the loss. The only problem I see with that equalizer is the size and cost. But it would be fun to build and use. Go for it.
I'm a beginner bass player. but this is my thinking about the frequency. I assume a four string bass with standard tuning. Right? so the low string an a "E". That is 41 Hz. There is not much reason to care about anything lower. So 32 is not unreasonable as a starting place. 50 Hz would not cover the range of even the four sting let alone a five string
A octave a a pretty wide range. the bass dos not make much noise above 3Khz
so 32hz to 4KHz seems about right The Hartke bass heads have a built-in EQ and use 32 - 8K in octaves and it works well although I don't kow why you need the high bands. Just fingers on the strings sounds and hiss, Not much "muci above a couple Khz
THis would a a great project. Now I need to find tube compressor
Read this starting at page 10. It talks about the effects of EQ on a bass and how to use it.
http://www.sweetwater.com/store/media/hartke_ha2500.pdf
(Sorry for the double post, I'm unable toedit.)
http://www.sweetwater.com/store/media/hartke_ha2500.pdf
(Sorry for the double post, I'm unable toedit.)
Re: Re: bass guitar preamp
thanks for you kind support. I've shrugged off the earlier nonsense.
I've built some ideas with pspice. the amp comes in via sensitivity control, volume to you and me, to a two stage 12ax7 amp. this drives a marshall stack. I then get another 12ax7 gain stage to get the level back up again.
or I might put in a cathode follower buffer then put it into a parametric eq. or i mi I've been doing some digging on this, a tube one is going to be too complicated, so i've got an op amp one instead. it uses gyrators with variable q, frequency and level controls. I might not use a tube buffer before it, and leave it opamp buffered instead.
It's how to display this in a meaningful manner that I am working on. Still thinking on that one.
I've got ideas for a compressor as well, but keeping that to myself just now. However take a hint and look at Fred Nachbaur site, and search for DOGZILLA. [regretfully Fred died a couple of years ago, but his website is still there]
Lots of ideas, lots to do.
kind regards
ChrisA said:
thanks for you kind support. I've shrugged off the earlier nonsense.
I've built some ideas with pspice. the amp comes in via sensitivity control, volume to you and me, to a two stage 12ax7 amp. this drives a marshall stack. I then get another 12ax7 gain stage to get the level back up again.
or I might put in a cathode follower buffer then put it into a parametric eq. or i mi I've been doing some digging on this, a tube one is going to be too complicated, so i've got an op amp one instead. it uses gyrators with variable q, frequency and level controls. I might not use a tube buffer before it, and leave it opamp buffered instead.
It's how to display this in a meaningful manner that I am working on. Still thinking on that one.
I've got ideas for a compressor as well, but keeping that to myself just now. However take a hint and look at Fred Nachbaur site, and search for DOGZILLA. [regretfully Fred died a couple of years ago, but his website is still there]
Lots of ideas, lots to do.
kind regards
Re: Re: Re: bass guitar preamp
My plan now I think is to include a "line out" (driven by a cathode follower) and "line in" jack. and only include a simple tone stack in the amp. My choice is forced because I'm rebuilding inside an Ampeg VT120 chassis and only have so many square inches to work inside. So a compressor and EQ in a second chassis my only option. But I think this would be a good plan in any case as there is less to build and debug all at once.
My plan now I think is to include a "line out" (driven by a cathode follower) and "line in" jack. and only include a simple tone stack in the amp. My choice is forced because I'm rebuilding inside an Ampeg VT120 chassis and only have so many square inches to work inside. So a compressor and EQ in a second chassis my only option. But I think this would be a good plan in any case as there is less to build and debug all at once.
billr,
I have to say that 4 bands is probably all that you need. When you try to split the bass guitar spectrum ( even to 5 or six strings ) you will have to design to such tight tolerances and then in the end it will drive you nuts because small changes in one or two bands will make your sound lopsided. Take a cue from the Pultec compressor. One big freakin knob. With four bands of EQ you will have the control you need. The GK uses contour buttons which are notch or bandpass filters inline with the EQ. This also works really well. I used to call the midrange killer my "Funk Button". So that is the design that I would use. 4 or 5 bands of EQ max ( even for 6 string ) and then maybe one or two switches to engage what you think might be a beneficial unique filter model inline with the eq. Also consider Total BYpass on the eq as an option , just to hear you actual sound.
I have to say that 4 bands is probably all that you need. When you try to split the bass guitar spectrum ( even to 5 or six strings ) you will have to design to such tight tolerances and then in the end it will drive you nuts because small changes in one or two bands will make your sound lopsided. Take a cue from the Pultec compressor. One big freakin knob. With four bands of EQ you will have the control you need. The GK uses contour buttons which are notch or bandpass filters inline with the EQ. This also works really well. I used to call the midrange killer my "Funk Button". So that is the design that I would use. 4 or 5 bands of EQ max ( even for 6 string ) and then maybe one or two switches to engage what you think might be a beneficial unique filter model inline with the eq. Also consider Total BYpass on the eq as an option , just to hear you actual sound.
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