Need Info: From scratch build for a high headroom clean amp

[skeezbo]

Geoff:
The JBLs that you would be lucky to find are the D-120 or K-120.
As far as the tone stack, try this easy mod if you still have a twin (or other hand-wired Fender) lying around. You may find you like the sound of a twin after all:

change your 100k slope resistor to 150k
leave the .1 cap in place
change the .047 mid cap to .010

This will give you a sample of what the skyliner sounds like. I put something similar in a Bassman 100 I was trying to use for bass (I didn't like the sound of the original tone stack either). The tone was greatly improved, but it didn't have enough power for bass. It does sound terrific for clean guitar, though, and it seems louder than my buddy's tweed twin that he built from a Mojo kit.

This mod sweetens the tone, to my ears, and sounds more high fidelity, somehow. The real Skyliner has a bigger treble cap (330P or 390p) and a 250k mid pot and some other stuff you may want to try if these changes take you in a direction that sounds good to you. If not, they are easy to put back. This tone stack and the Ampeg style PI and power amp that Andy suggested will take you way into SSS territory, if that is what you want. Good luck!

Skeez

[doctord02]

Might I suggest a variation on the Hiwatt DR-201:

http://ampgarage.com/forum/viewtopic.php?t=9030

[Geoff J]

Might I suggest a variation on the Hiwatt DR-201:

http://ampgarage.com/forum/viewtopic.php?t=9030

Yes you May !! WOW

Now that's what I'm talkin' about

So is there a parts list/layout/Schem for this beast ?

To keep things simple , instead of going for an fx loop, just hook up the ceriatone dumbleator clone and run fx through that ?

[doctord02]

Schematics are here:

http://mhuss.com/Hiwatt/tech2.html

I used the '70's 4 input preamp with only the normal input mated to the 4 KT88 power amp. No parts list or layout, but there's nothing out of the ordinary in the circuit.

[Geoff J]

Thanks much, I noticed that there are two 70's four input circuits - mid & early 70's

Which is best for guitar ?

Could I get the ceriatone kit for the 103, but use the kt's & the transformers w/the right bias resistor ?

[ckpop]

I'm a little confused because I have always been able to build for example a fender super head with plenty of headroom. Unless you are trying to build around your playing style, type of guitar, pickups and speaker I can understand building a very high output amp. In my opinion just a large output does not always get the result you my be looking for.

let us know your complete setup and the type of music you play to give us the big picture to throw some more ideas your way.

[Geoff J]

let us know your complete setup and the type of music you play to give us the big picture to throw some more ideas your way.

Thanls for the reply

SETUP:
EVM 12=L on a boogie cab
THD 2/12 (140 w of speakers)
Running in parallel into a TOnemaster 100W head (w/Merc mag OT, caps/resistor swaps, etc . . - almost got me there)
SED winged C's in there w/ALL JAN 12 AT7's

Guitars:
Howard Roberts (very low output PUPS)
Custom dual bucker axe w/7.3 neck & 8.8 bridge
Strat w/WCR SR's

PEDALS:
Real Tube , Barber Direct Drive, MJM blues devil, echo park, dod fx65 chorus, Clinch FX EP-PRE

Have tried my super reverb, a "twin" head into the same cab set up and other cabs w/the same results

Here is what I do musically
http://www.myspace.com/geoffreyjacob

There's alot of different stuff on there, so please don't try to pigeonhole my style in 8 measures

I am after that big deep clean SRV got on Texas Flood & CSTW (not SRV's Style as played through the amp, just the clean deepness)&/or That fat ass clean on Shine On You Crazy Diamond

Have yet to hear fender amps that can do that thick, rich, & deep clean at stage levels in big rooms w/o having to be at the mercy of a soundman's micing/monitor mix

From what I understand he was using a Dumble bass amp type circuit,and wanted an amp w/that same type of clean, thus his SSS being born
could be wrong on that one, but that's what I have heard from many.

That's why I'm thinking that the HIWATT or AMPEG bass amp type designs might be closer to that

I play in a 7000 sq ft theater, outdoors, & am going to be playing at big conventions, weddings, festivals , etc . . starting t the end of next month on

I don't want to have to be dependent on a sound man mic'ing me properly w/a good monitor mix

Also keep in mind that earlier post by a builder who said another guitarist who demanded big tubey cleans, had a 180 W amp built, PLUS Andy has been selling his Clean machines at 150 W which have 4 6550's

There is a demand for bigger cleans than the classic BF 100W circuits !

[doctord02]

I used the mid-70's circuit. Cant comment on the earlier one.

I think there are other differences with the 103, not to mention KT-88's will need more clearance between the tubes than the Ceriatone chassis allows. I already had a lot of small components around so I didnt think starting with a kit was cost effective. You want a lot of airspace around the KT-88's as they generate a lot of heat.

You can always email Nik at Ceriatone and ask, he's a good guy to deal with.

Thanks much, I noticed that there are two 70's four input circuits - mid & early 70's

Which is best for guitar ?

Could I get the ceriatone kit for the 103, but use the kt's & the transformers w/the right bias resistor ?

[ckpop]

Geoff with your setup and what you described I understand what you are try to achive. The problem with with most Fender amps if you were not getting the clean headroom you want is not nessarily just headroom power. The secret is getting the fullness and roundness going to your neck pickup without lossing definition and clairity in your tone. That is one small part of david gilmore, SRV sound. You will get that clean headroom and big deep bottom without more power if things don't muddy up.

I wish it was as simple as saying build this amp design and you will get exactly what you are looking for which to be real is hit or miss. You need the right preamp circuit design, EQ balance, gain structure along with the power. Building amps for 25 years this is one of the hardest things to learn and achive because you have to look at amp from an input to output stand point and everything in between.

I don't mean to over complicate your general question but I know how to do what you want but it took many years to figure just from building and tuning amps for years. I rather tell you straight up and be honestest to make sure you are heading in the right direction to get the result you want.

[Geoff J]

Thanks ckpop, so what is the first principle in going for such a design ?
In other words, how can this be distilled in a step by step fashion since there are so many variables ?

[skeezbo]

Geoff,
I think I get what ckpop suggests and it has merit: Fender and Fender style tonestacks can be too bassy. If you can control the frequency response of your preamp you can increase your headroom. Fender amps "fart out" easily if you like a woody tone with lots of bass. Tweek your preamp (think smaller coupling and cathode bypass caps) to filter out woofy lows that suck up power and cause speaker distortion. Dumble's 150k slope resistor seems to flatten out the bass response some, too. Suddenly the amp seems much louder, because you increased the clean headroom.

Even if you build a monster power amp you will probably need to fine tune the preamp in these ways to get the tone you are after, unless you want to sound like The Who (which of course is great). But I'll bet what you want is an amp that, if needed, can sound a little more like Wes than like Pete, but really loud!

Maybe a good place to start this process is to download Duncan's tone stack simulation software and experiment with different part values to see what is really going on.

I hope this helps
Skeez

[ckpop]

You are correct skeezbo, It's a balancing act to get the results. You change one thing and it affects another. The skill is taking away what you don't want without messing with with the good quailitiys of the the tone.

The secret is making a adjustments in the right part of the circuit. For example you want to trim the bass but still want the fullness, which cathode do you trim at ? Amp is to Bright ? do you change the fizz cap in the phase inverter, lower the treble cap or fattent up a cathode stage or coupling cap ? The best way to learn is jump in the water because everything you learn can be used down the line.