I'm afraid I'm a newbie when it comes to tube ckt design so I'll defer to the experts. Would there be an easy way to add treble and bass controls to this design? It's the one thing keeping me from plowing head-on into soldering bliss 
Active? Passive? Your thoughts are appreciated! TIA! -Cory
Active? Passive? Your thoughts are appreciated! TIA! -Cory
Attachments
Yes there is an easy way to add bass/treble controls, and simplest is to use a passive bass/treble.
I have attached a picture of a bass/treble control, this schematic is taken from a Marshall JCM 800 2210 preamp.
You simply add this control between your first stage and the next.
I have attached a picture of a bass/treble control, this schematic is taken from a Marshall JCM 800 2210 preamp.
You simply add this control between your first stage and the next.
Attachments
Passive is fine but put it in the right place
The original circuit in this thread shows a power amplifier. It is not customary to install any type of tone control within a power amplifier. The overall feedback within this amplifier would get badly out of whack by the addition of a tone control within the feedback loop.
A passive or active bass and treble control can be added at the very input of the amplifier. Care should be taken that the tone control circuit is driven from a low impedance source. Thus some kind of follower to drive it may be required. Personally I prefer the Baxandall tone control circuit, which is a one stage active type and is usually driven from a cathode follower.
John Fassotte
Alaskan Audio
The original circuit in this thread shows a power amplifier. It is not customary to install any type of tone control within a power amplifier. The overall feedback within this amplifier would get badly out of whack by the addition of a tone control within the feedback loop.
A passive or active bass and treble control can be added at the very input of the amplifier. Care should be taken that the tone control circuit is driven from a low impedance source. Thus some kind of follower to drive it may be required. Personally I prefer the Baxandall tone control circuit, which is a one stage active type and is usually driven from a cathode follower.
John Fassotte
Alaskan Audio
I've had a lot of luck with an active circuit from the RDH. It uses half a 6SN7, or a 6J5 for the treble, and one for the bass. It allows boost AND cut, 6dB per octave.
The problem with most passive controls is that they can only boost, and also that they cannot boost the midrange at all (even Fender circuits that have a midrange control!).
IMHO if you're using it for a hi-fi, you must go with active.
The problem with most passive controls is that they can only boost, and also that they cannot boost the midrange at all (even Fender circuits that have a midrange control!).
IMHO if you're using it for a hi-fi, you must go with active.
TONE CONTROLS
Hi,
I agree with you Joel.
Since he already expressed the desire to build a preamp as well I suggest an outboard active box (withe toobs of course).
By doing so all elements (pre and amp) stay intact and the tonecontrols can be brought into service when needed.
I quite like the circuit at headwize with all the CFs.
Cheers,
Hi,
I agree with you Joel.
Since he already expressed the desire to build a preamp as well I suggest an outboard active box (withe toobs of course).
By doing so all elements (pre and amp) stay intact and the tonecontrols can be brought into service when needed.
I quite like the circuit at headwize with all the CFs.
Cheers,
A lot of possibility here!
Hmm, that Baxandall circuit http://msswartz.tripod.com/baxandall1.htm looks like quite an elegant solution. Would it be permissable to couple my low-Z preamp to the power amp with such?
I'm still on the fence with whether to go with that, or something like Joel suggested. My previous amp used two halves of a 6SL7 in such a way, but the downside is a parts count of 2 dozen or so. I think the headwize ckt is a little extreme w/ 6 tubes for 2 channels.
With that amp I usually have the Treb control at 95% (I like my highs ) and Bass somewhere between half and full. Do you think I'd be satisfied with the Baxandall? It looks fairly popular.
Gunderz, yep it's a v-doubler circuit. Gotta get the 700v somehow
The trans is a 240v toroid at 1 amp!
The plan is to integrate both monoblocks and the preamp into one chassis. Add tone controls (w/bypass switch), IR remote, microprocessor control with LCD and 4 switchable inputs. The EL509 fil's take 2.5A a piece (the fil xformer is 20A!) At 150w per channel it should get the job done!
So what do you think? Will Baxandall cut it? Can I couple my pre to power with it?
Hmm, that Baxandall circuit http://msswartz.tripod.com/baxandall1.htm looks like quite an elegant solution. Would it be permissable to couple my low-Z preamp to the power amp with such?
I'm still on the fence with whether to go with that, or something like Joel suggested. My previous amp used two halves of a 6SL7 in such a way, but the downside is a parts count of 2 dozen or so. I think the headwize ckt is a little extreme w/ 6 tubes for 2 channels.
With that amp I usually have the Treb control at 95% (I like my highs
) and Bass somewhere between half and full. Do you think I'd be satisfied with the Baxandall? It looks fairly popular.Gunderz, yep it's a v-doubler circuit. Gotta get the 700v somehow
The trans is a 240v toroid at 1 amp! The plan is to integrate both monoblocks and the preamp into one chassis. Add tone controls (w/bypass switch), IR remote, microprocessor control with LCD and 4 switchable inputs. The EL509 fil's take 2.5A a piece (the fil xformer is 20A!) At 150w per channel it should get the job done!
So what do you think? Will Baxandall cut it? Can I couple my pre to power with it?
Re: WHY WORRY?
I can look it up tonight Frank, but it's near the end of the tone controls section.
Again, I have to say that I think the passive controls are not the way to go here, unless you're building a guitar amp. Just too much stuff coupling the stages. And they have a very sharp slope. Look at the response curves for the circuits also - the actives have nice gentle curves. Ooo lal la.
fdegrove said:
I can look it up tonight Frank, but it's near the end of the tone controls section.
Again, I have to say that I think the passive controls are not the way to go here, unless you're building a guitar amp. Just too much stuff coupling the stages. And they have a very sharp slope. Look at the response curves for the circuits also - the actives have nice gentle curves. Ooo lal la.
You make a good point about the headwize circuit Frank. I had dismissed it because of its 150/-150 supply reqs but I can steal that from the preamp supply. Could you tell me, what's the function of the 12AT7? Gain?
This may be the route to go, I have a source for motorized 10k pots and of course I've never needed an excuse to add more tubes
This may be the route to go, I have a source for motorized 10k pots and of course I've never needed an excuse to add more tubes
TONS OF CONTROL
Hi,
I doubt it.
You would also be better of with a separate box holding your circuit and PSU IMO.
Also you'll need heater supply,don't forget that either.
No,cathode followers are essentially buffers,the 12AT7 was probably chosen for its' lower output Z as opposed to the 12AX7.
Gain is defined by the input tube.
Cheers,
Hi,
I doubt it.
You would also be better of with a separate box holding your circuit and PSU IMO.
Also you'll need heater supply,don't forget that either.
No,cathode followers are essentially buffers,the 12AT7 was probably chosen for its' lower output Z as opposed to the 12AX7.
Gain is defined by the input tube.
Cheers,
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.