quote]I don't know if anyone else here notices or is it just me... but amps that have cathode follower driven tone stacks seem to yield a much better functioning master volume...Ever tried to put a master volume on a Blackface fender.. Then on a JTM 45..You'll find plenty of info out there about how cathode followers were designed low impedance to drive tonestacks but not much info on how it effects master volumes or Phase inverter loading..(or maybe I lust can't find it) With my loop in circuit I set my master on the amp at 12 o'clock and use the return on the loop as the master and to me get much better tone , sustain and responsiveness, liveliness at whisper volumes I can never get with just the master on the amp. which to me sounds splatty lifeless at low settings 1 or 2.. I would assume it's in the non loading characteristics of low impedance..Since cathode followers offer at best unity gain.. Anyone else notice this or am I swimming alone on this one....
Tony VVT[/quote]
Tony,
The Thevinin equivalent of a cathode follower / Mvol circuit is mostly determined by the cathode follower since it has a lower impedance compared to a common cathode Mvol circuit. This lower impedance has a greater effect on the tone.
Which half of Dum-ator contributes most to it's tone/effect?
Moderators: pompeiisneaks, Colossal
-
Mill Creek Audio
- Posts: 31
- Joined: Fri Mar 13, 2009 8:55 pm
- Location: Near Philly
- Contact:
Re: Which half of Dum-ator contributes most to it's tone/effect?
Been many years but as I remember there is so much signal coming off the SRPP that the devider network needed does present a pretty stable load, it used to sound very good but that was over 25 years ago and I can't seem to locate any of my old paperwork. Guess I'll just have to try one again and see how it sounds/works next to a cathode follower.
Any other folks found ways to deal with the phase issue?
Any other folks found ways to deal with the phase issue?
Re: Which half of Dum-ator contributes most to it's tone/effect?
BobTony,
The Thevinin equivalent of a cathode follower / Mvol circuit is mostly determined by the cathode follower since it has a lower impedance compared to a common cathode Mvol circuit. This lower impedance has a greater effect on the tone.
Thanks for that!!...So we all sort of agree on the tone..Good I'm not loosing it...YET!!.. So on to feel... Take a Blackface Vibroverb /Pro.. then a Fender Bassman do an AB test and run them up to gig volume.. To me the Bassman has this small area of compression right before it starts to break where the Vibroverb just hits the wall and breaks...You can do the same thing with a Twin and 100w say 2204..(just louder) You can really notice it if you use your fingers... I believe this to be the decreased loading effect on the PI...This also works with the Fender stand alone reverb units...Just not as noticeable...Sorry didn't mean to get on this follower kick..One of those things you can read about it but nobody ever goes into any depth on it's effects...All of them...The hoarse is now officially pronounced dead...
Tony
Re: Which half of Dum-ator contributes most to it's tone/effect?
Which Bassman ckt were you referring to? The Bassman AB763 is almost identical to the Pro or Vibroverb, but the AB165 is just another animal.
Since the Bassman iron is much bigger when compared to the Pro or Vibroverb, it probably is a big factor contributing to the compression at gig volume levels. The Bassman iron (OT) won't saturate as easily as the smaller iron, even during power supply sags.
Since the Bassman iron is much bigger when compared to the Pro or Vibroverb, it probably is a big factor contributing to the compression at gig volume levels. The Bassman iron (OT) won't saturate as easily as the smaller iron, even during power supply sags.
Re: Which half of Dum-ator contributes most to it's tone/effect?
The cathode follower has very little to do with why the tone sounds better with the loop. It is all about cracking open the 1m pot and using the 250k pot to control things. The follower does help with that. In addition to the EQ changes of the stage, the compression, and the cabling. The loop return master has nothing to do with the preceding follower stage when there is an effect inserted as well.
Of course I could be smoking crack......
Of course I could be smoking crack......
Re: Which half of Dum-ator contributes most to it's tone/effect?
Scott, I agree for the Dumbleator. Tony and I had strayed off the topic and were talking about cathode followers w/ Mvols in general. Thanks
Re: Which half of Dum-ator contributes most to it's tone/effect?
Yeah!! I know what you are talking about with respect to output transformer saturation that has it's own sort of compression associated and I recognize that..This is different..Sorry should have been more specific 5F6A...Maye we are getting into uncharted tone territory here..Since there has been no actual proof as to how impedance/loading effects tone... Aiken is the only one I have come across who directly relates it...I have designed and built several amps with different different iron and gain structures W/followers and without.. However the one thread that runs through them all is what I describe...I wouldn't have brought this up if I were just comparing the Bassman to a Blackface...entering the Wheeler Boundry..Which Bassman ckt were you referring to? The Bassman AB763 is almost identical to the Pro or Vibroverb, but the AB165 is just another animal.
Since the Bassman iron is much bigger when compared to the Pro or Vibroverb, it probably is a big factor contributing to the compression at gig volume levels. The Bassman iron (OT) won't saturate as easily as the smaller iron, even during power supply sags.
Scott I am curious why you would just crack the Master instead of open opening it up less clamped..Am I missing something... Just curious...It is all about cracking open the 1m pot and using the 250k pot to control things.
Tony..
Last edited by talbany on Fri Oct 02, 2009 1:16 am, edited 1 time in total.
Re: Which half of Dum-ator contributes most to it's tone/effect?
What are you asking? Can you rephrase?
Opening up the master reduces the series resistance on the signal. It also allows me to use a nice big bright cap and get the right amount of singiness that is smoothed by the loop cables.....
Works for me.
Opening up the master reduces the series resistance on the signal. It also allows me to use a nice big bright cap and get the right amount of singiness that is smoothed by the loop cables.....
Works for me.
talbany wrote:
Scott I am curious why you would just crack the Master instead of open opening it up less clamped..Am I missing something... Just curious...
Tony..
Re: Which half of Dum-ator contributes most to it's tone/effect?
Yeah I know that I was looking at it from the other end opening up the master increases the resistance to ground...shunting less signal/tone to ground there less clamping of the amp at the preamp out..Apples and oranges whatever the flavor..I seem to get a thicker meatier tone sending more signal through the loop and clamping it at the send pot where the impedance is lower.... Hey 2 each is own..Just wondering?... Obviously you like the tone better.. I know why bring it up... I hate MV Tone Suckers!!What are you asking? Can you rephrase?
Opening up the master reduces the series resistance on the signal. It also allows me to use a nice big bright cap and get the right amount of singiness that is smoothed by the loop cables.....
Works for me.
Tony
Re: Which half of Dum-ator contributes most to it's tone/effect?
Ahh.... Well I use a rack so my send setting is around 10-11 on a 250K audio. It is determined by my effects. I do attenuate with the send a bit as well as the return. With no effects I keep both around 11 oclock.
talbany wrote:Yeah I know that I was looking at it from the other end opening up the master increases the resistance to ground...shunting less signal/tone to ground there clamping the amp at the preamp out..Apples and oranges whatever the flavor..I seem to get a thicker meatier tone sending more signal through the loop and clamping it at the send pot where the impedance is lower.... Hey 2 each is own..Just wondering?... Obviously you like the tone better.. I know why bring it up... I hate MV Tone Suckers!!What are you asking? Can you rephrase?
Opening up the master reduces the series resistance on the signal. It also allows me to use a nice big bright cap and get the right amount of singiness that is smoothed by the loop cables.....
Works for me.
Tony
Re: Which half of Dum-ator contributes most to it's tone/effect?
ScottAhh.... Well I use a rack so my send setting is around 10-11 on a 250K audio. It is determined by my effects. I do attenuate with the send a bit as well as the return. With no effects I keep both around 11 oclock.
I didn't mean to imply by no means did you not know how to set up a rig..REALLY!!that's funny.. I read my post back and was hoping you wouldn't take that the wrong way.. And you didn't So thanks for playing along and sharing your settings...Too cool..
Here is an idea lets take all that thick fat harmonically rich carefully designed through 4 gain stages tweaked to perfection tone and right before it gets to the phase inverter dump half of it in the chassis...Brilliant.. Master Volumes..how I see it... Hate em!!
Tony VVT
Hey Bob
Would love to read any info you have on The Thevinin equivalent of a cathode follower ...If you have something related to our application would love to check it out. throw a brother a BONE!!
Re: Which half of Dum-ator contributes most to it's tone/effect?
Good thread. The roll off Gary mentions was bugging me a while back so I did some snooping and agree that the follower is flat and the recovery drops it off. When I disconnected the feedback loop though it still dropped off. When I bypassed the 220k//500p filter at the grid, the dropoff dissappeared. I cannot explain what is happening, just where it happens. Since my loops are always in circuit, I compensated elsewhere for the issue. Overall, I like what the loop does to the tone and agree the magic probably mostly happens in the recovery stage.glasman wrote:In my screwing around with the loop circuits I have found that the recovery side probably has the most effect (discounting cables). It has a high frequency roll off that starts about 400Hz or so and and drops off gradually. This is influenced to a large degree by the feedback network (or appears to be).
The CF is flat as a pancake from DC to daylight.
I have some graphs somewhere of measured results. I will see if I can dig them up.
Gary
Tony - I like using the recovery level as a master as well. I do this on my HRM/BM amps. Works great with no bleeder cap. I am about to try the same approach with a #124 inspired build. I will use the real master as the send to the loop on the back of the amp. The actual send level will be on an internal pot and the return level pot will be on the front of the amp as the master.
Re: Which half of Dum-ator contributes most to it's tone/effect?
I like what the loop does to the tone and agree the magic probably mostly happens in the recovery stage.
Not that my opinion matters much on this...Take the individual stages Follower/Effect/Recovery...Not real exciting separately that I see.. Put them together right before the power amp.. Wala! Magic...The combonation of componets that interfaces well...Icing on the cake!!
Tony VVT
Re: Which half of Dum-ator contributes most to it's tone/effect?
As you may know, Thevinin equivalent circuits just treat voltage sources as shorts and current sources as opens. Applying circuit analysis to Aikens convenient cathode follower tutorial / circuit, you can then determine the overall impedance of the circuit. Since this is just theory based on ideal components, imho it mostly goes out the window when we use our ears to tweak for the best tone anyway.Hey Bob
Would love to read any info you have on The Thevinin equivalent of a cathode follower ...If you have something related to our application would love to check it out. throw a brother a BONE!!
Scott's wonderful tone is a great example why it's best to trust your ears.
