Guitar amp(s) for nephews

It Had to happen
2 nephews one plays the bass, one the lead.
They are young so they want volume.. so I figure 70 to 100 watts.
I have a chap in australia who sells fender replacement gear but I wanted to use the 6550 in pp for ruggedness and maybe a pentode front end with an ixys current reg then of course an at/au for the phase splitter.
Tube rectification would be desireable.
So any of you got shematics for 6550 based amps specifically?
Wish me well
Thanks
 
what do they play?

Hey there
What do they play?
Why [email protected] of course!!!!
One neph is into metal but is very good (taste aside) at 17 its about rock N Roll
The other is more sophisticated in his music taste (bass player) you could classify him as INDIE/ alternative.
I know 15 watts is enough but i would rather give them something that isnt lame by 17 year old standards.. I remember if its too loud your too old and all that.
In the next few years i would expect thier tastes to change as they begin to identify the talent ou there in guitar land.. pink floyd/ the blues etc
Thanks
 

basstard

Member
2008-01-19 12:33 pm
metal guitar wants big volume,,, and if they gotta play together and the bass one wants to hear his instrument he'll need a decent collection of watts,,,

you could go split and do a poweramp for each and then build a pre so that you can change it over time when their taste changes,,,
 
Need to read up on stuff

No doubt guitar amps are hard. I didnt think for one minute that it would be otherwise.
I have found schematics to a lot of amps on el34 world.
I still think an e180f would make a great input valve and leave phase splitting to a 6sl7. The power stage would be a copy of a fender/marshall
If its all too hard I will just do a clone
 

Brett

Member
2002-01-07 6:02 pm
In my opinion (bassist) who lives with a metal guitarist, has lots of other muso friends and also designs, builds and repairs tube MI amps, 100W is too much. One third of that will give good breakup at sensible levels even for metal in the average pub type venue even lacking FOH support. I'd go EL34, or 6550 at reduced voltages, cathode biassed for maybe 50W.
The above assumes a half stack or similar for the cab.
 
thanks brett

Hi Brett
Thanks for the advice.
The problem i have is which bass and lead amp(s) sound good or are desired by guitarists? I dont know much about them at all in terms of that. If you could email me with some ides and where you get parts from I would greatly appreciated that.
6550 at reduced V sounds good cause it would add to their longevity
Thanks Again
Nick
 

basstard

Member
2008-01-19 12:33 pm
you sayin 100w for guitar or bass?

cos 100w for bass in a metal band aren't enough even if you use headphones,,, :D

100w for guitar are good,,, 50w I'd say it's too small,,,

guitar amps are not that difficult. if you clone a schematic everything will be ok.

I cloned a mesa boogie rectifier preamp and it went ok first time,,,
biasing the power tubes might be a lil more difficult,,,
the mesa rectifier imho is among the top amps for a metal guitarist,,, along with the 5150 by peavey, the JCM900 and the JCM2000 by marshall, the Soldano Super Lead Overdrive, those ENGLs all with similar names [powerball, thunderball or whatever they're called :D ], the ecstasy and the uberschall by bogner and some others,,, I'm sure I'm forgettin something,,,
 

Brett

Member
2002-01-07 6:02 pm
Re: thanks brett

duderduderini said:
Hi Brett
Thanks for the advice.
The problem i have is which bass and lead amp(s) sound good or are desired by guitarists? I dont know much about them at all in terms of that. If you could email me with some ides and where you get parts from I would greatly appreciated that.
6550 at reduced V sounds good cause it would add to their longevity
Thanks Again
Nick
Bass:

Bass is easy; almost without exception it's clean or with a small amount of distortion. You need a good DI in it and lots of clean power. For power pick up a good secondhand PA style amp from Yamaha, Jands or the like with the most power you can afford. As they're young, weight is less of an issue so the older main freq designs with a heavy PS are available fairly cheaply and definitely provide the most W/$ and reliabiltiy and value than even a DIY. I don't bother to build my own, and I got a Yamaha P7000S new cheap, for a better price than I could buy all the components. Two channels of a PA amp also allow for biamping and even better results in terms of wideband response and flexibility.

400W, with moderate or better efficiency is the minimum I would recommend for a gigging bassist in Oz as they will usually not be with FOH support.

Bass preamp: Simple good sounding and cheap can most easily be realised with Albert Kreuzer's pre.
http://www.albertkreuzer.com/preamp.htm

Tweak the values to work at 15V (fine at 9V, but gives more headroom when digging in) , add a DI, a buffered tuner out and a vintage style RC tone control and you'll have a very flexible pre for few $ that sounds great.
I have a couple of tube bass pre's I've been going to publish for a while, but details such as power tx's which are readily available, fit in a rack case and even the cases themselves are issues as I'd like people to built it if interested with minimum hassle. If you're willing to sort out those details, tell me what features size and cost and I'll neaten up a schematic and publish. Some don't use 12AX7's for better sound, but lesser parts availability in music stores.

The Kreuzer could be built into a die cast Al case and clamped to a mic stand.

If interested in bas cab designs, let me know as I have suggestions, but they're not quite conventional, and sound all the beter for it IMO. Were's not in the 60's any more, but most designs still are.

Guitar:

Here it gets murky as many component interactions produce the final tone. The speakers and cab need to be dealt with first.

Take with a huge grain of salt what pro's like EVH, Hammett etc use, except blues players as they'd likely play similar levels and venue sizes. They are sponsored, have roadies and play rigs the average Aussie pub band never will. Also, because they have certain gear on stage, it doesn't man that's what's actually processing the sound as for big players the sponsorship money is huge and easy.

100W sounds impressive, but the breakup and sag that comes from it and gives a goodly amount of the tone, simply won't happen at sensible levels given the EPA noise laws here, so powerbrakes, pulling tubes and other tweaks are often tried to get the desired tone at lower levels, so build a smaller amp in the first place. The 3dB difference betweem 50 and 100W isn't that great in terms of absolute SPL, but can be in terms of the knee where the tone begins to break.

Suggestion: build a clone of a preamp, or better yet, two different ones with a relay to switch between. It'll only add a modest cost and PS requirement for a massive increase in flexibility. For the powerstage, again clone or tweak an existing design. Do not build it like a good hifi design as undersized power and output Tx's are a part of the sound. Breadboard it and get him to practice with it a bit whilst finalising the design. Try a simple 6550 un pentode at 500-530V B+, but cathode biassed. Use individual cathode resistors and the Blumlein garter bias (search Tubecad) for simple reliable design. Works a treat.

Guitar cabs: I hate 4x designs. They're a pain to move, have combing ussues, an unless a full stack, put the drivers below waist level so they player is typically well off axis and increases volume to compensate and be heard (not good for ears or FIH guy trying to match stage and room levels). If you desire 4 drivers, build two 2x boxes. Add tophats into the top and bottom of each, and a 150mm length of 35mm dowel will hold them rock stable on stage. Also means he can take one to rehearsal or small gigs and two when needed. Add a flipout angle brace to the back of one of them so when used alone can be tilted back towards his ears so he can actually hear himself. Use Speakons for connectors and add a 200R 10W resistor in parallel across the 16R secondary to protect the OPT from plugging mishaps whilst powered up. A cabinet stand is also a good idea to raise the cab up maybe 600 off the floor.

End of rant. For more specifics, ask. Lots of details in the building of such that make the difference, ie no carpet on the cabs as it'll stink and looks cheap. Use Rockard or similar paint in Oz.
 

basstard

Member
2008-01-19 12:33 pm
2 2x12 cabs might look like a good idea but don't expect it's the same as a 4x12,,, air movements in the inside is not the same and that affects bass freqs by quite a lot,,, plus, today, 90% of 4x12 cabs have the two upper speakers tilted to point upwards and be heard better,,, and they're not that heavy c'mon,,,

for the bass PA, I'd say that class D might be a nice solution. I never tried it but as soon as I finish my current project [bogner ecstasy guitar preamp] I wanna try that for my bass rig,,,
 

Brett

Member
2002-01-07 6:02 pm
Somehow this got deleted from the reply above.

basstard said:
plus, today, 90% of 4x12 cabs have the two upper speakers tilted to point upwards and be heard better,,, and they're not that heavy c'mon,,,
Not all are tilted, and then the tilt is only a few degrees, which is of little use when placed on the floor and you're standing close to it as is the case on most stages I've used in Australia.

As for weight, it's more the bulk than the weight, although the weight can be an issue too. Two 2x cabs will stack nicely onto a handtruck ($25 at Bunnings) and also fit much more easily into the majority of cars and will fit through narrow doorways and staircases. The width and the distance between handles is also too great on a 4x unless your knuckles typically drag on the ground.
Having done a LOT of load ins/outs, it does make a difference. A HUGE difference.
 
100W sounds impressive, but the breakup and sag that comes from it and gives a goodly amount of the tone, simply won't happen at sensible levels given the EPA noise laws here, so powerbrakes, pulling tubes and other tweaks are often tried to get the desired tone at lower levels, so build a smaller amp in the first place. The 3dB difference betweem 50 and 100W isn't that great in terms of absolute SPL, but can be in terms of the knee where the tone begins to break.

Just my input. I have gigged with as little as 20 to 40 watts. A have a 20watt Fender Blues Deluxe clone, and that's what I need to get the tone I want. These days, you end up sticking a microphone in front of most stage amps anyway - at least I prefer that to DI into the big PA.
 

Brett

Member
2002-01-07 6:02 pm
hotbottle said:


Just my input. I have gigged with as little as 20 to 40 watts. A have a 20watt Fender Blues Deluxe clone, and that's what I need to get the tone I want. These days, you end up sticking a microphone in front of most stage amps anyway - at least I prefer that to DI into the big PA.
Agreed. The last harp amp combo I did was an EL84 based design of about 15W and with a pair of 12's, it'll take your head off.
 

basstard

Member
2008-01-19 12:33 pm
Brett said:
Absolute rubbish.

Thank you for being so humble,,,

You really sayin two 2x12 cab sound the same as a 4x12?

I bet this is the reason in every pro recording studio of the world they mic 4x12's while they could just make it simple and use a 1x12 following your idea,,, since the speaker is the same then it must sound the same no matter what enclosure right? no mate, you're wrong,,,

this is the reason there's so many different cab designs [open back, closed back, bass reflex etc.] and there's cab designing software,,,
 

Brett

Member
2002-01-07 6:02 pm
basstard said:
You really sayin two 2x12 cab sound the same as a 4x12?
Yes. If they are of the same total effective volume and design.

Get a say Marshall 4x12 and measure it physically. Now make 2 2x12 using the same internal volume and speakers. Place them side by side and measure. There will be no difference

Physics, mate. It doesn't lie.

As a 4x cab of whatever design is typically very close miked to one driver, it hardly matters if it is a 4x,2x or 1x desgn of the same general design and driver. As for 'all studios in the world', not so. I've seen all sorts of combinations used in the studio. On stage is the same. Last metal gig I went to had a large stack of 4x cabs behind the guitarists; only one of them had drivers in it.
 

basstard

Member
2008-01-19 12:33 pm
Brett said:
Physics, mate. It doesn't lie.

Physics also say that the signal going to the speakers has the same phase for each speaker but the air waves bouncing in the back of the cab will have different relative phase for each point of the cab so it matters not just the volume directly behind the speaker but also the volume around the speaker area,,,

Brett said:
As a 4x cab of whatever design is typically very close miked to one driver, it hardly matters if it is a 4x,2x or 1x desgn of the same general design and driver.

again, the movement of the speaker is *also* affected by the air waves coming from other speakers and bouncing on the back of the cab,,, so, no a 1x12 is NOT the same as a 4x12,,,

Brett said:
As for 'all studios in the world', not so. I've seen all sorts of combinations used in the studio. On stage is the same. Last metal gig I went to had a large stack of 4x cabs behind the guitarists; only one of them had drivers in it.

Obviously you only mic one cab cos a 4x12 has the same frequency response of a same model/make 4x12 so there would be no point in micing two or more.


I also understand that these differences can be not so huge but I didn't like the way you replied like you knew it all,,,
 

Brett

Member
2002-01-07 6:02 pm
Interesting that you quoted everything, except the most pertinent part about cutting up a Marshall and making it two 2x. I know there is no difference, because I have done it, not merely theorised upon it.

Two 2x are also a lot easier to move than one 4x, they stack neatly onto a hand truck, fit into the back seat of a small sedan, can be stacked vertically to reduce stage floorspace (often a big issue here) and reduce horizontal combing and can be used individually or together. Even if there was a significant difference in tone (there's not based upon my experience) these alone would allow many other advantages and possibilities than a single cabinet.

Remeber that reading text on a screen does not allow for the full communication that would occur if we were in the same room discussing the subject, so please feel free not to make assumptions about me.