Bluesmaster PI Values

[jborders5]

Decided to throw together a Bluesmaster based on Tony's REV6 layout today..... How critical are the 511 ohm and 9K resistors in the phase inverter vs the standard Marshall flavor of 470 and 10K? Should I wait until I have the correct values on hand or go with the Marshall values I have? Thanks

[wjdunham]

Decided to throw together a Bluesmaster based on Tony's REV6 layout today..... How critical are the 511 ohm and 9K resistors in the phase inverter vs the standard Marshall flavor of 470 and 10K? Should I wait until I have the correct values on hand or go with the Marshall values I have? Thanks

Hi Jason, it all depends on how good your ear is I've worked with players who can definitely tell the difference, and I'm sure HAD could as well. They are few and far between, names you have heard of and have incredible ears. FWIW the UP amps I've seen are all 470/10K with a mix of old Allan Bradley CC resistors and some newer CC and/or metal films, never seen two that have the exact same resistor types. If you have the 470/10K on hand you should be fine, you can try experimenting but best to have the rest of the amp dialed first.

Bill

www.sebagosound.com

[jborders5]

Decided to throw together a Bluesmaster based on Tony's REV6 layout today..... How critical are the 511 ohm and 9K resistors in the phase inverter vs the standard Marshall flavor of 470 and 10K? Should I wait until I have the correct values on hand or go with the Marshall values I have? Thanks

Hi Jason, it all depends on how good your ear is I've worked with players who can definitely tell the difference, and I'm sure HAD could as well. They are few and far between, names you have heard of and have incredible ears. FWIW the UP amps I've seen are all 470/10K with a mix of old Allan Bradley CC resistors and some newer CC and/or metal films, never seen two that have the exact same resistor types. If you have the 470/10K on hand you should be fine, you can try experimenting but best to have the rest of the amp dialed first.

www.sebagosound.com

Thanks Bill. I appreciate your input. I was able to meter a bunch of old Piher 1/2W carbon film resistors and found a 10K and 560 that measure almost perfect for the PI. Most of the amp will be vintage Pihers and I'm also adding an internal loop. We'll see how it turns out......

Bill

[bluesfendermanblues]

Please allow me to share my own experience with the Bluesmaster design. It can be a very frustrating design and BM should be regarded as a platform for modification rather than a useful design as is. If you search the forum, I think you would find that, this is a pretty general perception of the BM.

Being a STRAT player, I found the BM clean sound to quite fenderlike (blackface) with hollow mids etc., which can be fine depending your taste. However, as a consequence the OD will need PAB Megaboost (total tone stack lift/ or maybe a 22k to ground) in order to get anywhere near a Dumble'ish OD sound. The OD alone (without PAB) is not very interesting and sounds very raw in an unpleasant way.

Motive for trying out the BM in the first place, was to get more of a Fenderly (Chimy) clean - compared to the #102 and #183 (which are great for humbuckers), that I had already build.

I all fell into place when I tried the 2nd gen. design, which (for Strats) has a much better balance (than BM) between clean and OD. The Clean is great and (not too clean) and the OD sounds pretty much like the #102/#183.

Henry (member Heisthl) has a motto regarding these amps: "First get the Cleans right".

I guess a lot of us could have saved a lot of time, if we had followed that hookline, since many of us does the reverse, getting the OD right and focusing on the clean afterwards.

Just my 2 cents

[jborders5]

Thanks. One other question..... I always thought the megaboost on the Bluesmasters was just lifting the ground on the mid pot using half of a relay. I haven't traced a schematic out from the latest (REV 6) layout, but it there is clearly more going on with it. Has anyone built one using the latest layout?

[bluesfendermanblues]

Thanks. One other question..... I always thought the megaboost on the Bluesmasters was just lifting the ground on the mid pot using half of a relay. I haven't traced a schematic out from the latest (REV 6) layout, but it there is clearly more going on with it. Has anyone built one using the latest layout?

Yes, the MegaBoost is lifting the mid pot ground, but you might find the to be over the top. Put at trimmer in and adjust to the resistance that suits your taste. Measure the trimmer and replace with a fixed resistor of that particular value.

[trane34]

Fwiw I think the clean channel on a Bluesmaster is where the magic is, especially with slightly higher wound humbuckers. It's just a very touch sensitive input which I love and the tones are on the sweeter end of the spectrum. Not so steely like a blackface but more tweed bassman.

[jborders5]

Well it's up and running and actually sounds very good after I got the voltages where they needed to be. The only thing I question at this point is the mid boost. It works fine when in Jazz mode, but there is little to no audible change when in rock. Any ideas?

[Mark]

http://ampgarage.com/forum/viewtopic.ph ... luesmaster

I could rabbit on about my experiences, but best to post the links. If it isn't apparent I thought the PI had a certain sound about it, and the HRM tone controls seemed to load down the previous stage if set to low.

I used a 470 ohm and a 10K, I'm not sure if it is a big deal, I was more concerned about the tube I was using.

[talbany]

Not so steely like a blackface but more tweed bassman.

That's because it (pretty much is) a 100w Tweed Bassman..

Ages ago when I first started VVT amps we were looking at doing some slightly different takes on classic amps..I love 100w amps so I built myself a 100w (exact Tweed bassman replica) The thing was KILLER!!.. Touch sensitivity (even at low volumes) and had a great feel to it and worked GREAT with pedals!!..It never really caught on..100w amps do seem to stir up some real prejudice in fear of being too loud (even though the amp responded great at low volumes)..Some wouldn't even plug in..We quickly dropped it..It doesn't really surprise me to see people here liking the clean side on the BM..

The only difference worth mentioning is the Bassman uses a cathode follower to drive the stack. (it gives the amp a kind of sparkle and chime as well as a different more compressed feel vs a plate driven one) ..They also when pushed generate 2nd order and fatten the tone (great for Strat's)...Plate driven stacks are flatter in response and are not as bass heavy (Bassman's were Bass amps)..BM are plate driven..

Tony

[trane34]

Talbany, good to know my ears aren't too far off. The 100 watt tweed bassman sounds fun. What sort of filtering and iron did you go with?

[talbany]

Talbany, good to know my ears aren't too far off. The 100 watt tweed bassman sounds fun. What sort of filtering and iron did you go with?

I built that amp a while ago (eventually went into the ether) If I remember I used MM OPT a High powered Tweed Twin (could have been a FAT Stack!!).. I think I used 50uF on the plates (2X100 in series) and 40uF on screens..That one had 6L's (TAD Short Plates)..I even think I used my stash of CF Allen Bradley's and CTS pots..As we all know the output section (PI, NFB) is great for 34's (if your going for more of a Marshall type vibe)..The Power was an off the shelf/Heybour Twin and ran around 450 (under load)..I ran mine through a 4X10 Marshall straight front cab sounded just great!!!..Also I remember that amp (as with most Bassman type circuits) worked really ,really well with my 60's PNP germanium Fuzz Face and a Strat.. Hendrix,Cream,Early Gibbons and Bramhall II tones out the whazoo!! (also my Clay Jones modded 808 was magic), Better than the OD side of my BM for sure!!..I MISS that amp..Note to self..Build another one!!

I have a 80ww now that (with a few pedals) covers a Ton of ground (2XKT88 loaded 6PS Spragues and Dralorics.Old RN 70's on plates) That I LOVE..Just not the same as that 100..

Tony

[jborders5]

I know I'm in the minority, but this circuit could become my favorite new amp...... I should preface that I've been away from tubes for quite some time and literally had not plugged into an amp for over a year. I gig 2 - 3 time a week (corporate function/wedding reception band) and had been using an Axe FX II for the last couple of years. Recently I picked up a Carol Ann OD3 on a trade and the Axe has been idle as I found my renewed love for tubes....

The amp is still not 100% dialed in, but it's definitely going out for a couple of gigs this weekend. Cleans are great and the OD reminds me of a nice old Marshall. The OD is very David Grissom sounding to my ears with how I have the tone stack set right now.

The amp was originally an Emerald Pro clone with a passive loop and different reverb circuit. It's been modded a few times with different HRM and non HRM circuits.... The reverb is now gone and a 2 knob dlator has been installed in it's place (send level on the back and return on the front as a global master).

[img:800:531]http://imagizer.imageshack.us/v2/800x60 ... 5/wa3l.jpg[/img]

[Structo]

Looks like a very nice build.

If I ever have disposable funds I would like to build a HRM and a Bluesmaster.

[dreric]

John,

nice build, tidy!

good looking boards, RJ's?

haha