Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => PC Express and JSchem - Schematics and Layout diagrams => Topic started by: tubenit on March 24, 2009, 08:13:51 am

Title: Carolina Blues Rocket 5879
Post by: tubenit on March 24, 2009, 08:13:51 am

I have now built and tweaked this amp.  It sounds great!  I've built 4 different amps in this chassis and this is by far the most touch sensitive and expressive.  It does not have the same degree of overdrive as the HoSo 56 of DaGeezer's but I am using NFB which gives it a better sound to my ears. I have the NFB switchable.

I'm using Tung-Sol 5881's and the harmonics and touch sensitivity with the amp is great. The 5879 does have a very nice fat tone with it.  I played the amp with 6V6's also which sounded great but not as sweet harmonics as 5881.

I'm pleased with the amp.   It is not as loud as the Carolina Blues Rocket that borrowed alot of Dumblish preamp topology nor does it have the sustain.  But the CBR 5879 is far more touch sensitive in playing. It is plenty loud with room to spare to play with the band I sit in with.

UPDATE: 3/25/09

 With my guitar on 10,  the amp volume (5879) on 7 and the trim pot on 5 ............ I can sustain a note til it feedbacks.  This is with the mstr vol (crossline) not engaged but turned off.

I discovered I do like the PAB but on this amp (but for some reason) the treble pot needs to be turned to 10 with the .002 cap paralleled to get the tone I like.  I may just leave it as is. Playing along with a CD the boost feature cuts thru very nicely.  I initially wasn't sure if I was going to like the PAB.

I compared the 56T and the CBR 5879 side by side playing along with the same song on a CD and without any background music.............    The results are:

I would say they are equally touch sensitive.  The sustain is about the same on both, so the overdrive is fairly similar.   However, the 56T has a more distortion & has a really sweet tone to the distortion.  The CBR 5879 is a cleaner sounding overdrive but still sustains great.   The harmonics are close to the same with the 56T having a little stronger harmonics (w/some chime).

I think the CBR 5879 has less chime and more warmth to it. I don't use NFB on the 56T and strongly prefer it on the CBR 5879.  The CBR has a stronger bass to it with 5881's and a larger 12" speaker compared to the 10" Ragin Cajun on the 56T.

That's probably the best I can describe it and make comparisons. Hope that helps for anyone considering it. I probably would loose the NFB switch and build the "presence" control fixed. I leave the presence control at around 3 and don't adjust it.


With respect, Tubenit

You can find most of these schematic in the "Broken Links" file.  Write down the name of what you are looking for and then click on to this Broken Links file list:

http://el34world.com/Forum/index.php?topic=17420.0 (http://el34world.com/Forum/index.php?topic=17420.0)

Title: Re: Carolina Blues Rocket 5879
Post by: tubenit on April 01, 2009, 07:25:44 am

With alot of help from Sluckey, jjasilli, and PRR ........... I added a really rich lush warm deep sounding vibrato to this amp. It is the very best sounding vibrato of any amp I've owned or played. Very cool sounding, IMO.  It did NOT add any noise to the amp that I can tell or alter the tone in any way other than adding vibrato to it.

With the fat warm sustain of the 5879, this is a wonderful sounding amp to my ears! Using the vibrato and cranking the amp a little ........ I can do a pretty decent imitation of the amp tone, Billy Gibsons is getting on "Sharp Dressed Man". The notes will sustain into feedback if I want.

There are several Dano/Silvertone schematics that use a 1M slope resistor on the intensity pot  (Dano Centurian #275 & Silvertone
1433).  I measured the max on the pot and it is 446k (due to the 1M paralleling the 1M pot) and I like the vibe best on 364k.

I could not be more pleased with this amp! If you're looking for a 22w amp with a fat warm sustain/overdrive (with vibrato) this would be worth considering.

Best regards to the forum guys & thanks for all the help!  Tubenit

Title: Re: Carolina Blues Rocket 5879
Post by: tubenit on August 23, 2009, 06:28:21 am

OK, OK ............... DaGeezer keeps coming up with new ideas (like paralleled pentodes). What can I say?

I removed the vibrato and paralleled a 5879 with a 5654 (or 6AU6) to get a fat/thick harmonically rich sweet tone.

It was an easy mod to do and didn't take much time at all.

NOTE:  while I drew this to indicate building a VVR from scratch. I plan to use another one of Dana Hall's VVR3

EDIT: the sch schematic and layout is correct ....... I changed some of the values in the color coded layout

With respect,Tubenit