Line Out Output Jack Design

[purpletele]

I have been reviewing options for running amps in stereo and was intrigued by the post on Doug's circuits/ AC4 below.

I am considering utilizing a line out jack for my Hoffman 18 Watt 6 v 6.  It has a 16 Ohm, 50 Watt speaker.

I am understanding that the resistance values for my NFB circuit to be 47K and 10K respectfully.

If use those values in the equation for parallel impendence, then I get a perfect match of Z=16 Ohms.

So, if it is as simple as that, and I use those resistance values in the Line Out output jack then I can run and instrument cable to my Stout and operate in stereo?

Thanks for any advice

BV

[jojokeo]

I wouldn't use that method Brian for a number of reasons. It's far better to split your guitar signal and run it into both amp's inputs so you can control each one independently.

[purpletele]

I wouldn't use that method Brian for a number of reasons. It's far better to split your guitar signal and run it into both amp's inputs so you can control each one independently.

Enough said!

Thanks Joe

[PRR]

> Hoffman 18 Watt 6 v 6.  It has a 16 Ohm, 50 Watt speaker.
> NFB circuit to be 47K and 10K
> If use those values in the equation for parallel impendence, then I get a perfect match of Z=16 Ohms.

I do not follow that math.

I don't see how 47K and 10K make 16 Ohms any which way.

The NFB in the circuit you cited is 47K to 5K, the 10K goes somewhere else.

If we take 18 Watts at 16 Ohms we get 17 Volts. At the 47K+5K junction this may be 1.6V. That's not really a guitar level. And obviously: the circuit has two high gain stages between guitar and this point.

The 1.6V "would" be a good level to drive a naked (no preamp) Power amp. But I would give that output its own divider, so the external power amp does not muck with this amp's internal NFB. And I might drop impedance to 4.7K and 1K, because the 16r tap can easily drive 4.7K, and the 1K is a better fit if you have to drive a very long line.

[purpletele]

^^^^^Thanks  I see the error in the resistor value.

I think I am going to head toward the external switching box method.

Bad math gets me in trouble

[jojokeo]

A line out is easy to add to the back of your chassis. If serious you'd want to also allow for the addition of a small cap preserving high end and maybe put on a switch. Then the dropping resistor would be made a pot so that you could control the amount of signal out. But the issue you proposed initially is using the signal after the entire amp circuit.
 
Why not have a "Send or Master jack" from your main amp which would not interrupt the signal going to the power amp and speakers. Then run your preamp circuit from your primary amp into the Return jack of your "slave" amp's power amp section? To me it's either this way or as I said earlier where you can control both amps independently to sound their best together as a whole.

[Ed_Chambley]

I have for years exclusively used 2 amps.  One amp gets the modulation effects when needed and the other gets dirt.  Small venue I use a Princeton Reverb with Tremolo and put my Chorus, Flanger, Echo....etc and an AC15 with the second board of dirt and fuzz.  Works fantastic even when I stack them.


Larger setup is a Brown Bassman with 2, 12 Altec 418 and I actually use modulation in front of this one and Super Reverb with Weber Alnicos and use boosts and dirt in front.  I get to use this about 2 times a year, but when I do man is it Kewl.


Right now at my second home I have a Gibson GA5 and a SE homebrew EL34.  Both have 8" speakers.  This is my baby stack. 


I use a Radial Hotshot to split the signals.  Nice unit and has a phase switch which is important if you dive into the 2 amp deal.  Sorry, not a hot shot, but a Radial Big Shot ABY.

[jojokeo]

I was just looking at one of those yesterday Ed. I couldn't see or find a power input jack and was wondering if it is merely a switching box or not??? Enquiring minds want to know ;)
So do you actually stack them on top of each other? Is it usually either one or the other or do you sometimes run both at once? If so how do you regulate the volume jumps? Importantly, will you switch between amps during or only between songs? I'm naïve in this set-up - please help. If you want to hit me up on my private e/m that may be best? I need photos and audio samples please :)

[Willabe]

If you want to hit me up on my private e/m that may be best?

I think we'd all like to know more please.   

[Ed_Chambley]

I was just looking at one of those yesterday Ed. I couldn't see or find a power input jack and was wondering if it is merely a switching box or not??? Enquiring minds want to know ;)
So do you actually stack them on top of each other? Is it usually either one or the other or do you sometimes run both at once? If so how do you regulate the volume jumps? Importantly, will you switch between amps during or only between songs? I'm naïve in this set-up - please help. If you want to hit me up on my private e/m that may be best? I need photos and audio samples please :)

No Joe, much simpler.  Guitar>Bogshot output 1>pedlaboard 1 Dirt>AC15.  Bigshot output 2>pedlaboard 2 Modulation>Princeton.

Volume control is on amps and pedals.  I run a modded Boss Graphic in front of my modulation pedalboard for a volume control and tailor effects.

If stage room permits I tilt back the wet amp and keep the drive amp forward facing unless the staging is higher.  Then I am using the bigger bottle amp and I separate them by only a few inches.  As you know you never want cabinets with different signals touching.

Since my Bassman is now completely restored and looks almost new (9 out of 10) Found an original never used faceplate it has tilt legs and thumbscrews.

If I must stack them due to limited space I separate them using a flight case top and I have 1 inch conduit pipe I slide down on the back to keep them from getting knocked off.  This is only with my AS16 and Princeton as I made the cabs the same width and depth. Actually the Princeton is a Combo with 2 10's and sits atop the AC15 head and them on the cabinet.

From a distsance it looks like I am playing a Tweed, 2 10 super on a brownface.  Man I wish I would have not thought of that.  Having my 5F4 with my 63 Vibroverb clone would be killer.

Loops, we don't need no stinking loops.  Really, you know my ears don't you.  I have amps with tube loops, mosfet loops and series loops and the all change the tone.  The latest that K gave me a schemo for is the best tube loop I have used, but still you lose your dry signal.

I consider a dry signal with a boost or dirt still dry.  To me a wet signal is Modulation.  It is actually easy to balance the blended mix because all my geetars will reduce drive way before modulation so if playing something where I need to get low and pretty all I do is roll back and the clean amp drops under the modulation.

Let me know if this makes sense.

[jojokeo]

Yes, you confirmed what I was thinking - thank you. The amp tilting and placements helped too. I did a bit of research on various loopers, a Morley Triple switcher and ABC, and a few others but I take it that the Radial with the smaller switches makes things reliable and easiest? Have you had much use for the phase switch before? Being that we're so diligent with our amps I find it hard to imagine that this would be something of concern? But maybe you never know why it occurs unless a speaker (or cab) is possibly miswired? Unfortunately one of the local venues we seem to play most has a real small stage area so the stacking info will likely really come in handy.

Last question to confirm which I think I know the answer already ahead of time, would you use the lower powered amp of the two for the dry and higher powered with more headroom as the wet?

[Ed_Chambley]

Yes, you confirmed what I was thinking - thank you. The amp tilting and placements helped too. I did a bit of research on various loopers, a Morley Triple switcher and ABC, and a few others but I take it that the Radial with the smaller switches makes things reliable and easiest? Have you had much use for the phase switch before? Being that we're so diligent with our amps I find it hard to imagine that this would be something of concern? But maybe you never know why it occurs unless a speaker (or cab) is possibly miswired? Unfortunately one of the local venues we seem to play most has a real small stage area so the stacking info will likely really come in handy.

Last question to confirm which I think I know the answer already ahead of time, would you use the lower powered amp of the two for the dry and higher powered with more headroom as the wet?

Yes, the lift switch is necessary when using the Bassman and Super as they are original amps and they will hum without it.  Ground loop and I refuse to put a 3 prong cord on the 62 Bassman.  I promise I am careful and check the outlets with a meter to insure I wont get a shock.


The volume for Modualtion is why I use the princeton with 2 10,s and the AC15 has a single 12.  All speakers are 100spl.  Remember Joe, I rarely get into distortion area these days when gigging since I get hired to play Country mostly and mostly traditional country.  Also, I do the Travis style and Rockabilly in the style of Scotty Moore. I think you know this, but that doesn't mean this setup will not work for you gigs.  You will just have to find what works, but even when just playing with old friends for fun and I do break out on something like Beautiful Girls I just step on a Wampler Pennicle which that and a slow flanger is very convincing tone of VH2.


I am not on the west coast as you are and I love playing Stones and even Van Halen, it is not what I am known for simply because I am either playing Atlanta or North Carolina Mountains where Americana, Bluegrass, Old Timey and Pre Beatles Rock reign, unless in Asheville where the hipsters just go for anything.  In Atlanta we have all the Rap Stars now, but I do get to play at a couple of Fairs outside the city where it is rural and they love Haggard and Skynyrd.


Back in the late 70's and through the early 80's my main axe was a Ibanez Gambale with a Floyd Rose, but I also used a Marshall 50/50 and a Rocktron Voodoo Valve with an old ampeg 4, 12. Things were different and it was acceptable to have a loud amp, so cutting through was no problem.  Remember?  Now I need the dry amp for this and this is why I went this route.  I can still be heard and keep the stage volume low.  You know how easily a EF86 to EL84 AC15 distorts so think about where my volume is to be able to play clean.


Since the Bassman is a Brown model it get some hair on the notes early, whereas the Super reverb being 40 watts actually has more clean headroom and is an AB763.  You know the 12At7 PI vs the Bassmans 12Ax7 PI.  I actually have the NFB disconnected on the super to lessen some of the punch.


I really need a Ampeg for 70's Stones.  I got the Catlinbread SFT pedal, but through a Fender it is not too convincing.  Through my Marshall Plexi it is, but the Plexi boxes me in.  I tried my Fargen ole 800 build Copy with my 68 Plexi and it is just ok.  I can get a good clean from the 800, but I am giving up what the amp is so I use it for Dry and to me a Plexi does not sound very good with Reverb or Echo.  I did get to use both of them at a friends wedding, but he is 5 years older than me and wanted Zepplin, Bad Co and it worked well, but that is rare as hens teeth these days.


All and all I believe the Princeton reverb and the AC15 are the best because I can use either clean as well and you really need a Fender clean tone if you've Gone Country.  I do have a Twin and a Deluxe too, but where can I use a Twin?  The Deluxe is my grab and go when I am heading to a friend that does a lot of recording.  He writes and arranges the tunes and gets me to do guitar.  With his studio I have found a Deluxe and a few pedals to work best as he will reamp and double up and all that junk that I never cared to do.


He is the guy that mixed the 2 finger style tunes you heard.  I promise I am not THAT good.  Willabe cornered me on this remark, so I will say I did play the stuff but all the errors were edited out and I make a lot of those.


Let me know if this answers your concerns.  If not, ask away.  I am like most people, I love talking about me.

[purpletele]

^^^^^I think that this is the type of solution that I am after. 

Thanks for the description.

BTW ED, you mentioned that you do not want different cabinets with different signals to touch. 

Can I ask what happens and why?

[Ed_Chambley]

^^^^^I think that this is the type of solution that I am after. 

Thanks for the description.

BTW ED, you mentioned that you do not want different cabinets with different signals to touch. 

Can I ask what happens and why?

If the cabs are touching and you are close to them you will hear a vibration because modulation effects cause the speakers to react with the phase shifts whereas your dry will be consistent.


Most times the audience will not hear, but the audience doesn't care if you tone is perfect either.  Tone inspires me to play a certain way and cabinets rattling inspires me to get pissed off.  Then my ears change and I don't like my tone.  Then I throw my guitar across the stage and hit the Bass Player who is generally twice my size.


Then he whips my butt and I get a bloody nose and stuff and someone asks me what happened and all I can say is my cabinets were touching.


Then everyone who suspects me of being weird is now convinced.  So I guess you could say if your cabinets are touching, you are weird.


Seriously tho, you will hear them rattle.

[Ed_Chambley]

^^^^^I think that this is the type of solution that I am after. 

Thanks for the description.

BTW ED, you mentioned that you do not want different cabinets with different signals to touch. 

Can I ask what happens and why?

It takes a little work, but it beats the snot out of trying to cut through using delay in a loop.  Plus you never have to deal with the end of the song effect lingering.  I always simply step on my splitter shutting down the wet amp while doing the zinger.  You know, the little jam we do at the end.

[purpletele]

^^^^^I think that this is the type of solution that I am after. 

Thanks for the description.

BTW ED, you mentioned that you do not want different cabinets with different signals to touch. 

Can I ask what happens and why?

If the cabs are touching and you are close to them you will hear a vibration because modulation effects cause the speakers to react with the phase shifts whereas your dry will be consistent.



Well then, I'm a weird one as well.

Thanks

Most times the audience will not hear, but the audience doesn't care if you tone is perfect either.  Tone inspires me to play a certain way and cabinets rattling inspires me to get pissed off.  Then my ears change and I don't like my tone.  Then I throw my guitar across the stage and hit the Bass Player who is generally twice my size.


Then he whips my butt and I get a bloody nose and stuff and someone asks me what happened and all I can say is my cabinets were touching.


Then everyone who suspects me of being weird is now convinced.  So I guess you could say if your cabinets are touching, you are weird.


Seriously tho, you will hear them rattle.

[Willabe]

Tone inspires me to play a certain way and cabinets rattling inspires me to get pissed off.  Then my ears change and I don't like my tone.  Then I throw my guitar across the stage and hit the Bass Player who is generally twice my size.


Then he whips my butt and I get a bloody nose and stuff and someone asks me what happened and all I can say is my cabinets were touching.


Then everyone who suspects me of being weird is now convinced.  So I guess you could say if your cabinets are touching, you are weird.

                          Dog gone giant bass players!