Peavey 6505+ head using Multi-FX headphone jack

inflames · 2011-03-16T09:26:24+00:00

Hi all, I'm considering getting Peavey 6505+ from the states in June when a friend takes a jet for a service in Miami. With the baby arriving in 4 weeks time, there is no way in heaven and hell that I can play this in my house! So I read a interesting article, but don't understand it at all, maybe you can help. I understand I need to run the head into a cab otherwise a big explosion will happen ? Now the theory of this guy is that you can run the head into cab, but then use FX loop or pre-amp out to send the signal to a multi-fx unit. Plug your earphones in and jam without using the cabinet for output. This would be super cool and the only way I can think this will work is use the pre-amp out? Thanks ladies and gents!

inflames

Thanks guys,

Got my answers from Alan and Gearhead.

I can get the amp for a steal, so that is the main reason.
I was just going to buy it and let is stand for occasional use at venues.
Was just looking for a way to maybe use it with headphones.

Gearhead

Hey Inflames, we all know how it feels, moenie worrie nie. If you've set your mind on a piece of kit, you gotta have it. Stop making sense, start having fun ?

inflames

Gearhead wrote Hey Inflames, we all know how it feels, moenie worrie nie. If you've set your mind on a piece of kit, you gotta have it. Stop making sense, start having fun ?

HE HE, jip agree!

BMU

Agree. "Because I want it" - still the very best reason to buy a piece of kit. ?

Tonedef

Is there any other reason? ?

FenderBender

Gearhead wrote If you screw this http://za.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=1074147 onto a heatsink, you will be klaar.

I use various Arcol aluminium housed resistors in the Tube Tamer. They are rock solid if you use the correct heatsink or derate according to what they will be mounted on. The 50W unit Gearhead mentions here needs a heatsink with a maximum thermal resistance 1.74oC/W to achieve full dissipation at ambient temperatures up to 35oC.
Something like this: http://za.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0104086

Another option is to derate the resistor and mount it straight into a metal case (that will get hot) without heatsink. You can choose a 75W or 100W unit as they are rated at 45W and 50W respectively without a heatsink.

If you have a 6505 plus you will need to dissipate 120W!
There are several options available and cost, practicality and physical size need to be factored in.

Here are two options:

1. A 6.8 ohm, 150W unit: http://za.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=3091251
mounted onto this monster: http://za.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=4907309

2. Two derated 33 ohm, 300W units in parallel: http://za.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=6150577
without a heatsink, mounted in a metal case.

I downloaded the 6505 plus head schematic and manual studied it a little.
There is no "power amp input" jack to stick a blank plug into. Not that this matters for what we are doing here though.
The head has a output impedance selector, so this broadens the options for finding suitable resistors.
Peavey have added an adjustable bias pot to the plus model. See my end note for the benefit of this.

It is also possible to derive a line out straight from the output of the amp, This will allow you to feed a line level signal with true power tube distortion to a speaker/cab sim and get a fairly good representation of the cranked amp on headphones. A lot of PT, but as BMU states, if you want it, you want it ?

End note:

In the old 5150 days, Peavey preset the bias fairly cold, using fixed resistors. One of the best mods for the 5150 is to add an internal pot to be able to adjust bias within a safe margin of 50% to 70% of nominal tube output. I have done this on a few 5150s and the adjustment made a big difference to the tone of the amp, effectively varying the headroom available for the output, which in turn determines when the tubes start running into distortion. It's nicely explained here: http://tubedepot.com/whisbipo.html

Gearhead

The difference between pro and amateur is once again clear... :-[

FenderBender

LOL@Gearhead! I disagree. It's just that I have a feeling inflames will ask me to build this for him, so I worked out a few permutations in the meantime that will save time later and shared my findings with the forum ?

inflames

Thanks Graeme,

Once again you kick some ass!
That sounds brilliant!

I'm going the rack mount route, so if we can build this unit to fit into a rackmountable case that will be great!
I already started looking at cooling methods for rack cases!

Will pop in somtime this week and chat to you!
Also need to check how the wire tap is going!

Cheers buddy :goodtimes:

FenderBender

@inflames: Pleasure mate!

Mounting in a rack case should be easy enough. What I did find interesting is that there are water cooled resistors available!
http://za.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=2523044

Probably not a good idea for you though! ?

I sent you an email re the wire tap earlier ?

See you later mate!

Gearhead

...or, if you want it to sound like a proper tube-tranny-speaker interaction kinda thing, you correct for frequency dependance of the impedance like Randall Aiken does: http://www.aikenamps.com/spkrload.html

FenderBender

Gearhead wrote ...or, if you want it to sound like a proper tube-tranny-speaker interaction kinda thing, you correct for frequency dependance of the impedance like Randall Aiken does: http://www.aikenamps.com/spkrload.html

Very nice! Speaker sim and dummy load in one. It would be easy to pull a line level signal from the input and take that off to a headphone amp or sound card with phone socket.

inflames

Gearhead wrote ...or, if you want it to sound like a proper tube-tranny-speaker interaction kinda thing, you correct for frequency dependance of the impedance like Randall Aiken does: http://www.aikenamps.com/spkrload.html

Nice! That would be killer!

inflames

Graeme Parfett wrote
Gearhead wrote ...or, if you want it to sound like a proper tube-tranny-speaker interaction kinda thing, you correct for frequency dependance of the impedance like Randall Aiken does: http://www.aikenamps.com/spkrload.html
Very nice! Speaker sim and dummy load in one. It would be easy to pull a line level signal from the input and take that off to a headphone amp or sound card with phone socket.

This would be like a pocket pod on steroids ?

Styles

Use Revalver MKIII for the 5150 sound on a budget or if you can't crank it at home. . . use a cheap 16 or 8ohm 5 inch 100w speaker.
Connect a speaker cable to the terminals. Put said speaker in container filled with old blankets or pillows.
Take the FX out signal into your soundcard.
Download BOOGEX and some free speaker cab impulses.
Run your preamp signal through that in your DAW and Bob's your uncle.

5150 sound through your PC, and you can get the 5150 tone without bothering anyone?

You should be able to do this with the Tubetamer as well. . . and it's a good investment.

inflames

Thanks Styles!

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