50w highgain mod

[gldtp99]

The AFD Prototype Assembly demo clip contains tracks by three different amps:
1) Marshall 4010 1x12 50 watt combo modded similar to your 50 watter---has EL34's--- running thru 4x12 cab--- rhythm track
2) 4 gain stage EL34 50 watter--- orig a Laney AOR 50--- now a turret board version of DBM's AFD/Slash layout-- rhythm track
3) 14 watt EL84 w/mods mentioned in earlier post--- rhythm and both solo tracks (w/Wha-wha pedal)

All these amps are over at my workshop and i won't have time for several days to go get them------ which one(s) are you interested in ?
Your 18 watt blues clip sounds great !!!....................gldtp99

[dukeamps]

The AFD Prototype Assembly demo clip contains tracks by three different amps:
1) Marshall 4010 1x12 50 watt combo modded similar to your 50 watter---has EL34's--- running thru 4x12 cab--- rhythm track
2) 4 gain stage EL34 50 watter--- orig a Laney AOR 50--- now a turret board version of DBM's AFD/Slash layout-- rhythm track
3) 14 watt EL84 w/mods mentioned in earlier post--- rhythm and both solo tracks (w/Wha-wha pedal)

All these amps are over at my workshop and i won't have time for several days to go get them------ which one(s) are you interested in ?
Your 18 watt blues clip sounds great !!!....................gldtp99

Hi gldtp99, thanks for the feedback on the 18watt'er.

Only if it’s not too much trouble the 2 50w amps interest me. The AFD Prototype Assembly demo clip has some really nice distortion going on there.

Cheers

Nigel

[gldtp99]

Ok, give me a few days and i'll show the two 50 watters used on that clip, how they're built.
I suspect that there's nothing all that special about these amps compared to AFD/Slash-type amps that many others have been doing. A few differences, here and there, but nothing earth shaking.
I think what you're hearing has more to do with the fact that my friend James did the clip than any special amp mods.
First of all he used a baritone Gibson Les Paul, not a standard guitar---he also recorded three rhythm tracks (panned left/right/center) with three different amps---- he uses this recording technique in his own modeling/computer based recordings and did the same thing here with three of the modded live tube amps---- blending different amps tends to fatten up the tone by a huge amount--- the left and right tracks were recorded at the same time using an A/B/Y box----the center rhythm and solo tracks were recorded individually.
James also is a talented player with a great sense of "touch"----he can play many different instruments, sounding at home on all of them---- playing almost any style of music you can name----- my amps always sound instantly better when he plays through them vs my playing.
But anyway, i'll spill the beans on these 50 watt amps because you asked.................gldtp99

[dukeamps]

Ok, give me a few days and i'll show the two 50 watters used on that clip, how they're built.
I suspect that there's nothing all that special about these amps compared to AFD/Slash-type amps that many others have been doing. A few differences, here and there, but nothing earth shaking.
I think what you're hearing has more to do with the fact that my friend James did the clip than any special amp mods.
First of all he used a baritone Gibson Les Paul, not a standard guitar---he also recorded three rhythm tracks (panned left/right/center) with three different amps---- he uses this recording technique in his own modeling/computer based recordings and did the same thing here with three of the modded live tube amps---- blending different amps tends to fatten up the tone by a huge amount--- the left and right tracks were recorded at the same time using an A/B/Y box----the center rhythm and solo tracks were recorded individually.
James also is a talented player with a great sense of "touch"----he can play many different instruments, sounding at home on all of them---- playing almost any style of music you can name----- my amps always sound instantly better when he plays through them vs my playing.
But anyway, i'll spill the beans on these 50 watt amps because you asked.................gldtp99

Hi gldtp99, Thanks for getting back to me. Don't sell yourself too short, still have to have a good amp to start with, but also thumbs up for the other guys. Looking forward to hearing from you soon.

Cheers

Nigel

[gldtp99]

Gut pics:http://s46.photobucket.com/albums/f112/ ... AFD%20Mod/

1) V1a-- plate is 82k (680pF bypass)/.015uF--- 68k grid--- cathode is 2.7k/.68uF
2) V1b-- plate is 82k/.015uF--- grid is 100k (replacing 470k/470pF)--- cathode is 10k/.1uF
3) V2a---grid voltage divider is 390k (no bypass cap)/470k to ground----cathode is 820 ohm/.68uF
4)PI coupling caps are .047uF Xicon MPP's
5)Lar/Mar PPIMV mounted in former DI jack position on back panel
6) I left in the stock 4010 V1a plate-to-cathode cap (100pF) and Mid pot wiper-to-ground cap (.0047uF)---wanted to see how it sounded before removing them---it's ok
7)New F&T Filter Caps--- all cans 50uF/50uF---- restructured filtering so that there is 50uF on output tube screens----- stock 4010 has 100uF on screens
8)Stock iron--- GT EL34M output tubes--- Blackburn Mullard ECC83 in V1--RFT ECC83 in V2--- RFT ECC83 in PI

This 4010 came to me with the Sozo's and some whacky mods installed---sounded like crap--- i restored it to stock preamp specs and it was underwhelming at best----- it sat in storage until i did these AFD-type mods, new Filter Caps, etc.
Now some think it's the best sounding of the five AFD-type modded amps i've done lately, when running through a 4x12----- but all my five AFD modded amps have some players who think that they are "The Best One"-- i was hoping that one (or a couple) out of the five amps would be considered better sounding than the others but i've found that different players seem to like different amps------everyone who has played all the amps likes them but they pick different amps as their favorites---good for my ego but not much help from an amp builder's perspective.
I'll post about the 4 gain stage EL34 50 watter later..................gldtp99

[dukeamps]

Gut pics:http://s46.photobucket.com/albums/f112/ ... AFD%20Mod/

1) V1a-- plate is 82k (680pF bypass)/.015uF--- 68k grid--- cathode is 2.7k/.68uF
2) V1b-- plate is 82k/.015uF--- grid is 100k (replacing 470k/470pF)--- cathode is 10k/.1uF
3) V2a---grid voltage divider is 390k (no bypass cap)/470k to ground----cathode is 820 ohm/.68uF
4)PI coupling caps are .047uF Xicon MPP's
5)Lar/Mar PPIMV mounted in former DI jack position on back panel
6) I left in the stock 4010 V1a plate-to-cathode cap (100pF) and Mid pot wiper-to-ground cap (.0047uF)---wanted to see how it sounded before removing them---it's ok
7)New F&T Filter Caps--- all cans 50uF/50uF---- restructured filtering so that there is 50uF on output tube screens----- stock 4010 has 100uF on screens
8)Stock iron--- GT EL34M output tubes--- Blackburn Mullard ECC83 in V1--RFT ECC83 in V2--- RFT ECC83 in PI

This 4010 came to me with the Sozo's and some whacky mods installed---sounded like crap--- i restored it to stock preamp specs and it was underwhelming at best----- it sat in storage until i did these AFD-type mods, new Filter Caps, etc.
Now some think it's the best sounding of the five AFD-type modded amps i've done lately, when running through a 4x12----- but all my five AFD modded amps have some players who think that they are "The Best One"-- i was hoping that one (or a couple) out of the five amps would be considered better sounding than the others but i've found that different players seem to like different amps------everyone who has played all the amps likes them but they pick different amps as their favorites---good for my ego but not much help from an amp builder's perspective.
I'll post about the 4 gain stage EL34 50 watter later..................gldtp99

Hi gldp99, thanks for the great info, I also use rft ecc83s, they sound fantastic in marshalls, the rft el34s are also great.


Cheers

NIgel

[gldtp99]

I worked from this schematic made by DBM:
[IMG:800:566]http://i46.photobucket.com/albums/f112/ ... FD-DBM.gif[/img]

The amp started life as a Laney AOR 50 made in 1987--- i gutted the PCB and built a 50 watt (turret board) version of a Krankenstein from the schematic online--- it sounded much like a real 100 watt Krankenstein owned by the former studio engineer across the hall--- but it wasn't my cup of tea so i made some changes (changed plate-driven tonestack to cathode follower driven and some value changes)---i still wasn't all that happy with the amp's tone.
Then i found DBM's #39 schematic online and re-did the preamp along those lines----- but keeping the much higher power supply filtering values from the Krankenstein-type design. The Krankenstein power supply also doesn't use a choke, so it's been removed. I'm too tired now to trace out the amp but here are gut pics:
http://s46.photobucket.com/albums/f112/ ... AFD%20Mod/
This amp is running a nice pair of RFT EL34's---- V1:RFT ecc83--- V2: JJ ecc83s---V3: Mazda (England) ecc83----PI:EI 12ax7.
This one has a Resonance control between Treb and Mid pots (was the Sweep control in the Krankenstein circuit)---- and it has a "Power Dampening"-type 2nd MV instead of a Lar/Mar PPIMV.
It's not all that pretty inside after being built as three different types of circuits----- but it works well and has a thicker/fatter tone than the #34-type, 3 stage amps IMO.
If anyone would like me to go through the amp and identify the values on the preamp tubes like i did on the other amps ----- just let me know and i will------ otherwise the pics and DBM's schematic should provide enough info to get what's going on with this one........................gldtp99

[John_P_WI]

Good stuff Gldtp!

Would you or DBM please post or pm a higher resolution schematic? My tired eyes cant quite make out the #39 you posted.

Thanks, any hints to the PI power damping circuit would be appreciated too.

John

[gldtp99]

Here's where i got the DBM schematic----- scroll down to reply #32:
http://www.el34world.com/Forum/index.php?topic=2467.0
The Power Dampening-type MV has been discussed before-----it's pretty simple---- a 50k RA pot (wired a variable resistor) placed between the PI cathodes and the 470 ohm resistor----it only works with a LTP phase inverter----- it's not bad if used lightly, if used heavily the amp's EQ must be adjusted----it also can add to the distortion level if used heavily.
Scroll down to reply #11--- http://www.el34world.com/Forum/index.php?topic=3496.0

[John_P_WI]

Great Thanks Gldtp99!

I have been loosely following the SIR thread over on Metro and it is overwhelming with the # of pages. I will check out the links on Hoffman's forum that you pointed to.

Thanks,

John

[dukeamps]

Hi gldtp99, thanks for the info.

Here is the way i have my amp.

#36 mod

Stage 1 input 33k shield to ground. Cathode 2k7/0.68uf/ coupling cap 0.022uf/ 470k/500pf 1meg a pot/ 1000pf bright cap silver mica.

Stage 2 Shield on anode. Cathode 10k/.1uf/ coupling cap 0.022uf/ 500pf over the 100k plate resistor. 470k/500pf/470k.

Stage 3 Cathode 10k coupling cap 0.022uf 100k plate resistor. 470k/500pf/470k.

Stage 4 Cathode 820r/0.68uf.

Tone stack 33k/250pf the rest stock.

100pf fizz cap

NFB 47k/0.47uf /4ohm tap.

Stock power amp


Cheers

Nigel

[dukeamps]

Hi Guys, I have just found this mod.

http://img263.imageshack.us/img263/9439/36mod.jpg

Have any of you ever tried this before?

I'll Maybe give it a go myself.

Cheers

Nigel

[gldtp99]

Hi Guys, I have just found this mod.

http://img263.imageshack.us/img263/9439/36mod.jpg

Have any of you ever tried this before?

I'll Maybe give it a go myself.

Cheers

Nigel

I haven't seen that one before------ why a 10k/.1uF on V1a and a 2.7k/.68uF on V1b ? Usually it's the other way around, isn't it ? Maybe it works well that way. I haven't really liked any of the plate driven tone stack circuits i've tried---in this type of amp, anyway.
I'm happy with what i've found with the AFD-type amps i've done so far----even with all the different variations i've built/modded the main tone character comes through, and i like it------ but now players here are mentioning that there's really very little usable clean tone to be had with these amps (no kidding !!)----- so my next step will be to build Clean/Lead channel switchers with an AFD-type Lead channel.
The 1st two will be lo wattage heads------ lots of players really like my 14/7 watt #34 head (lead tracks w/wha pedal on AFD Prototype Assembly clip) but need a usable clean tone to go along with it----- and most want a transformer-coupled balanced DI Out for home recording/FOH------ some also are asking for an FX loop.
I have output iron for a 10 watt single ended 6L6GC build and for an ECL86 x 2 push/pull build----- two new Edcor XPWR105 PT's will power these builds: http://www.edcorusa.com/products/702-xpwr105_120.aspx
Both OT's are pulls from Bogen PA amps---- these should be interesting builds------ once i get the Clean/Lead preamps tweaked out i can build larger versions-----i have some custom wound Heyboer PT/OT sets that will support KT88 x 4 or 6L6GC/EL34 x 6 builds @150 watts.
But what i've found is that the 14/7 and 25 watt AFD heads are more popular (and much easier to stand in front of) than the 50 watters----- using PPIMV's or attenuators can limit the 50 (or larger) watters but the smaller amps can be cranked up and played flat out without PPIMV's or attenuators, and the overall sound is better with the smaller amps----- up to a certain vol level where a higher wattage amp is necessary. (or if the player needs to feel hi-wattage THUMP)
The 1st two channel switchers will have BF Fender-type clean channels with three gain stages (1st stage>tone stack>2nd stage>3rd stage)--- this will eliminate phase difference between the two channels (with a three stage AFD-type Lead channel) and will also more closely match the vol level of the two channels vs the normal two stage non-reverb BF Fender preamp.
I'm also thinking about building an AFD-type Lead channel with a Hiwatt clean channel (in a channel switching head) in the future---i'll see how these first two lo wattage (Fender clean channel) switchers come out first.
Hmmmmm....................a 150 watt Hiwatt/AFD channel switcher----- now that might be worth building !!! I do have a Partridge OT laying around rated at a conservative 120 watts that orig ran EL34 x 6-- ....................gldtp99

[Darkbluemurder]

Good stuff Gldtp!

Would you or DBM please post or pm a higher resolution schematic? My tired eyes cant quite make out the #39 you posted.

Thanks, any hints to the PI power damping circuit would be appreciated too.

John

John,

I am sorry but this is the only picture I have left. Somehow the original SPlan file was overwritten. Basically it is a 2203 with an extra stage and the following deviations:

1. Only one input, grid stopper 47k which was there from a previous mod and I did not bother to change it.

2. No bright cap on the gain pot.

3. On the cathode of the 2nd gain stage there is a switch that puts another 10k in parallel to the existing 10k for a slight gain boost.

4. The interstage voltage divider between the 2nd and 3rd gain stages is a 470k II 1000pf into 390k to ground.

5. On the cathode of the 3rd gain stage there is a switch that puts a 0.68uf cap in parallel to the 10k for a boost.

6. The interstage voltage divider is 1 meg to ground ínto 470k II 1000pf into a 470k to ground.

7. The cathode resistor on the 4th gain stage is 1k.

8. The bass cap in the tone stack is a 0.047uf for more bass. There is a 1000pf cap from the mid pot wiper to ground.

9. Before the master volume there is a 470k series resistor. After the MV wiper there is a 100k resistor.

10. PI and output stage is stock Marshall Super Bass. Presence cap is 0.68uf. NFB resistor is 47k from the 8 ohms tap.

I hope this clarifies the values. BTW I have modded that amp to different values now which I happen to like better.

Unfortunately I am not set up to do clips or pictures of the amp.

Cheers Stephan

[John_P_WI]

Nigel and Gldtp99,

I did not follow the link too closely but it looks very similar to Kevin O'Connor's 4 stage high gain marshall mod from TUT. Roccafortes HG100 amps follow a very similar design. KOC maintains the low input between the 2nd and 3rd stage for clean tones.

Instant Zakk Wilde pinch harmonics if that is what you want. If you dump some of the high freqs across the plate resistors and a cap to ground after the master volume you can get the Splawn tones easily.

My guess is the 10k on the input cathode helps limit the noise which would be amplified all the way through.

John