yes, too bad this potis with the switches are that hard to find! A lot of 80ties amps used them. I would need some replacements for my Kitty Hawk amps too. If someone knows a source somewhere on the globe, please tell us
Boogie MKIIA Rev Eq 60/100W
- Thread starter mark2boogie
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mark2boogie
Well-known member
Hi guys,
Well, you can find new CTS 1M LOG (audio) pots with push-pull switch (pull=ON=contact closed) at banzaieffects.de , which are quite similar to the old ones...
But for other values, it's hard-to-find... I have a few NOS in A250K, B250K and A1M for my personal amp maintenance that I found by chance on trashed equipment many years ago.
The 250K you are speaking about is certainly a LOG taper. To have an idea, try this measurement tip :
1 - measure the total R of your pot
2 - at HALF position, from 0 pin to CT pin :
- if you have circa half the total R value, then it's a LIN or close to
- if you have circa 10 (usually), 15 or 20% of the total R Value, then it's a LOG or close to
A+!
Well, you can find new CTS 1M LOG (audio) pots with push-pull switch (pull=ON=contact closed) at banzaieffects.de , which are quite similar to the old ones...
But for other values, it's hard-to-find... I have a few NOS in A250K, B250K and A1M for my personal amp maintenance that I found by chance on trashed equipment many years ago.
The 250K you are speaking about is certainly a LOG taper. To have an idea, try this measurement tip :
1 - measure the total R of your pot
2 - at HALF position, from 0 pin to CT pin :
- if you have circa half the total R value, then it's a LIN or close to
- if you have circa 10 (usually), 15 or 20% of the total R Value, then it's a LOG or close to
A+!
mark2boogie
Well-known member
Hi All,
Here are some pics of my MKIIA with its "matching" Thiele EVM12L cab in Tolex Suit.
The Tolex combo is fitted with an Emincence ME12-100PE-8 (which is nowadays the Legend 1218) for portability - I left an EVM12L in the Hardwood combo. It has not the efficiency of the EVM12L (something like 6dB by ear, I do not took measurements), nor the weight (3.8kg instead of 8.6kg, 1lb = 0.453kg), nor the power handling (150W against at least 200W). Nonetheless the ME12 compares to the ALTEC 417-8H as I found it during A/B trials, has a little bit more efficiency, is cheaper and lighter.
The association of the ME12 combo plus the EVM Thiele cab offers large, interesting sounds, should I say something like "both of 2 worlds", but without discarding the EVM alone in combo. Alone, the ME12 breaks-up earlier than the EVM, and has less ability indeed to widsthand the basses at 10 at high level on the 100W/8ohms position. At 5, it's OK, and this speaker sounds great and smooth, unagressive, with that "grittt" in the highs you find on the ALTEC 417-8H and not on the EVM12L.
A+!
Here are some pics of my MKIIA with its "matching" Thiele EVM12L cab in Tolex Suit.
The Tolex combo is fitted with an Emincence ME12-100PE-8 (which is nowadays the Legend 1218) for portability - I left an EVM12L in the Hardwood combo. It has not the efficiency of the EVM12L (something like 6dB by ear, I do not took measurements), nor the weight (3.8kg instead of 8.6kg, 1lb = 0.453kg), nor the power handling (150W against at least 200W). Nonetheless the ME12 compares to the ALTEC 417-8H as I found it during A/B trials, has a little bit more efficiency, is cheaper and lighter.
The association of the ME12 combo plus the EVM Thiele cab offers large, interesting sounds, should I say something like "both of 2 worlds", but without discarding the EVM alone in combo. Alone, the ME12 breaks-up earlier than the EVM, and has less ability indeed to widsthand the basses at 10 at high level on the 100W/8ohms position. At 5, it's OK, and this speaker sounds great and smooth, unagressive, with that "grittt" in the highs you find on the ALTEC 417-8H and not on the EVM12L.
A+!
Sounds and looks great. I also bought a Thiele EV12 cabinet and got it one week before christmas. Since then I had some nice gigs with this combination. A little more bottom and a broader soundstage, not much of a difference, since the Mk II has a lot of bass on demand itself.
BTW: I have an old Altec Lansing 417-8C laying around somewhere, a very nice speaker. Put it once in my BF Deluxe which made the amp twice as loud and very nice sounding, but also a lot heavier. After a while I changed back to the original Fender Oxford. For the Boogie its 70Watt rating is too low, even though I have the 60 W MK II version.
happy new year
BTW: I have an old Altec Lansing 417-8C laying around somewhere, a very nice speaker. Put it once in my BF Deluxe which made the amp twice as loud and very nice sounding, but also a lot heavier. After a while I changed back to the original Fender Oxford. For the Boogie its 70Watt rating is too low, even though I have the 60 W MK II version.
happy new year
SonicProvocateur
Well-known member
Looking classy mark2! Is that a Hagstrom?
I have a pair of those Eminence speakers I pulled from a 2x12 sealed back cab and I just put 1 in a converted ported cab. Still love their tone for rock and roll! Not really a heavy metal speaker, but covers all the ground under it, awesome breakup!
I have a pair of those Eminence speakers I pulled from a 2x12 sealed back cab and I just put 1 in a converted ported cab. Still love their tone for rock and roll! Not really a heavy metal speaker, but covers all the ground under it, awesome breakup!
mark2boogie
Well-known member
Thanks ! - Yes, it's a LH Hagstrom Viking in Cherry Transparent, on which I added the Bigsby B-7. This guitar is under estimated : she's able to compete with my 1980 ESS-335, trust me...
Indeed ! The Eminence ME12-100PE8 is also an underestimated speaker (as the Legend 1218 today) : I love its smooth tone and breakup as far as I hate the PittBull behavior of too many Celestions...
A+!
Boogie'sFrenchLover
Member
Salut Mark2boogie!
C'est un super post, tu as fait un sacré boulot sur la partie electrique.
Nice job !
A+
C'est un super post, tu as fait un sacré boulot sur la partie electrique.
Nice job !
A+
jpdennis
Well-known member
Mark2boogie
Thank you so very much for this post. Great ideas.
Dennis
Thank you so very much for this post. Great ideas.
Dennis
mark2boogie
Well-known member
Thank you guys !
Just wisely remember to not try this if you are not enough confident in your knowledge and skills, with adequate tooling : it's not a beginner task... But if you well-trained, then consider my post as a guideline. The improvement is worth the job and time devoted to... Your MKIIA will thank you by sounding like never before.
A+!
Just wisely remember to not try this if you are not enough confident in your knowledge and skills, with adequate tooling : it's not a beginner task... But if you well-trained, then consider my post as a guideline. The improvement is worth the job and time devoted to... Your MKIIA will thank you by sounding like never before.
A+!
mark2boogie
Well-known member
Hi All,
As I needed one Boogie logo, I tried to order it from MESA USA, from which I had an answer inviting me to contact my local dealer (a good friend) in France. It took him nothing less than 4 months to obtain 2 logos from the MESA french importer... for the astronomic cost of 20 Euros (say circa 28USD) : amazing, indeed. Here they are, compared to the original late 70's/early 80's logo from my MKIIA. Next time, I'll probably go to my local plate and emblem engraver/etcher, and have them copied à l'identique...
Fortunately, the 2nd one is assorted to the one on my Tolex Thiele cab, and has exactly the same screw distance as the vintage one, which now will stay on my hardwood cab.
One day, I will have to find another MKII chassis for the Tolex cab, if I can...
A+!
As I needed one Boogie logo, I tried to order it from MESA USA, from which I had an answer inviting me to contact my local dealer (a good friend) in France. It took him nothing less than 4 months to obtain 2 logos from the MESA french importer... for the astronomic cost of 20 Euros (say circa 28USD) : amazing, indeed. Here they are, compared to the original late 70's/early 80's logo from my MKIIA. Next time, I'll probably go to my local plate and emblem engraver/etcher, and have them copied à l'identique...
Fortunately, the 2nd one is assorted to the one on my Tolex Thiele cab, and has exactly the same screw distance as the vintage one, which now will stay on my hardwood cab.
One day, I will have to find another MKII chassis for the Tolex cab, if I can...
A+!
very interesting: I got the blue alu logo on my Thiele cabinet. Does someone know when they started to use the blue logos?
On my MkIIB there is the old logo with the grey shades:
@mark2boogie: so you decided to leave your Amp in the hardwood cab? Now you need a wooden Thiele cabinet. I remember I saw one on ebay some time ago.
On my MkIIB there is the old logo with the grey shades:
@mark2boogie: so you decided to leave your Amp in the hardwood cab? Now you need a wooden Thiele cabinet. I remember I saw one on ebay some time ago.
mark2boogie
Well-known member
Hi TiPiMods,
I would say mid-80's maybe... Maybe Daniel "Igfraso" can confirm, among others ?
Well... Yes and no ! In the Hardwood cab, this is the EVM12L Black Shadow version, which weights as heavy as 42.5 kg in its flycase, so it is an anvil. In case I have no one to help me for carry it, I switch to the Tolex cab, which I equiped with an Eminence ME-12-100-PE8, for a mere 24.5 kg in its padded cover, along with I can add my matching Thiele EVM12L cab. About the wooden cab, I have been in contact with a very kind guy from Germany or Austria which builts fine Thiele cabs ( I bought from him my EVM12L Black Shadow), but I have some reticences because of the fragility of the nicely finished wood surfaces, compared to the Tolex.
I am nonetheless thinking to find another MKII... Then a head plus an ALTEC 417-8H cab "hardwood" would be an alternative... So wait and see !
A+!
I would say mid-80's maybe... Maybe Daniel "Igfraso" can confirm, among others ?
Well... Yes and no ! In the Hardwood cab, this is the EVM12L Black Shadow version, which weights as heavy as 42.5 kg in its flycase, so it is an anvil. In case I have no one to help me for carry it, I switch to the Tolex cab, which I equiped with an Eminence ME-12-100-PE8, for a mere 24.5 kg in its padded cover, along with I can add my matching Thiele EVM12L cab. About the wooden cab, I have been in contact with a very kind guy from Germany or Austria which builts fine Thiele cabs ( I bought from him my EVM12L Black Shadow), but I have some reticences because of the fragility of the nicely finished wood surfaces, compared to the Tolex.
I am nonetheless thinking to find another MKII... Then a head plus an ALTEC 417-8H cab "hardwood" would be an alternative... So wait and see !
A+!
mark2boogie
Well-known member
Hi All,
That Boogie MKIIA Rev Eq 60/100W is still a wonderfull amp, and my main one... So wonderful that I have found a MKIIB Rev Eq 60/100W head, as I was looking only for a MKIIA or B chassis.... And so put on a new subject on the forum about it...
A+!
That Boogie MKIIA Rev Eq 60/100W is still a wonderfull amp, and my main one... So wonderful that I have found a MKIIB Rev Eq 60/100W head, as I was looking only for a MKIIA or B chassis.... And so put on a new subject on the forum about it...
A+!
mark2boogie
Well-known member
The return of the ALTEC 417-8H... I traded a fine well-played 417-8H for the servicing of a friend's 1965 VOX AC30 Top Boost.
I think that it will stay in my tolex cab, now... Different from the EVM12L, but truly good-sounding, very warm and with that sweet little "shrill"...
Note that two tube shields needed to be cut-slanted, because of the width of the basket arms of the 417, larger than on the EVM12L :
A+!
I think that it will stay in my tolex cab, now... Different from the EVM12L, but truly good-sounding, very warm and with that sweet little "shrill"...
Note that two tube shields needed to be cut-slanted, because of the width of the basket arms of the 417, larger than on the EVM12L :
A+!
Hi there,
I am not a frequent poster but I come around here from time to time.
I have a 1979 Mark IIA (60W, non reverb) that I bought attached to a rack mount adapter, nothing else. I bought a Combo shell and a vintage EVM 12L to have a complete package. The main problem with this amp is that it hummed like crazy so, after 5 year of intermittent work on it (I had two kids during this period) I manage to reduce the noise to acceptable levels. This is what I did:
0) Change the power transformer to an export model (I am from Spain, this won't affect to most of you)
1) Replace all carbon comp resistors with metal films. A resistor from the filtering section literally blow up on a rehearsal, decided to change all of them.
2) Replaced all pots with new CTS, with switches when needed. The Volume 1 pot (Input Gain) hummed like crazy at high level setting but stopped humming when reaching 10. This was indicative that the problem was on the pot.
3) Changed the diode that gets the DC voltage for the relay with a diode bridge. The relay made a loud treble hum when activated (clean channel) due to the fact that the DC voltage was not really DC but had a big AC component.
4) Changed the relays with new ones, this helps to reduce the loud pop when changing channels. I still get a pop, at a much lower level thou. Still, I think something can be improved here.
5) Very important, grounding reorganization. Pots, cathode and filter capacitor share the same ground bus on the preamp board. This introduced a loud bass hum.
a) Pots are grounded on a separate part of the chassis. I just used a hole near by and used an screw that fitted there to attach a soldering point for the ground.
b) Left the ground points from the cathodes of the preamp tubes are on the ground bus.
c) Preamp filter capacitor is now grounded on the same ground of the rest of the filter capacitors. This is the responsible for most of the loud bass hum.
6) Heater voltage on the preamp, replaced it with a twisted pair of cables. The heater voltage runs on two separated bus on each side of the board. This can introduce mayor hum on the cables near by. To prevent this I replaced this bus with a twisted pair where the noise from one cable cancels the hum from the other.
To do this mods I had to cut some of the board bus and this was a major decision for me. But do not regret it, now the hum level is extremely low for a 33 year old high gain combo.
Hope you find this helpful!
(Ps: I originally posted this on the Mark IIB topic, but I think it makes much more sense to post it here)
I am not a frequent poster but I come around here from time to time.
I have a 1979 Mark IIA (60W, non reverb) that I bought attached to a rack mount adapter, nothing else. I bought a Combo shell and a vintage EVM 12L to have a complete package. The main problem with this amp is that it hummed like crazy so, after 5 year of intermittent work on it (I had two kids during this period) I manage to reduce the noise to acceptable levels. This is what I did:
0) Change the power transformer to an export model (I am from Spain, this won't affect to most of you)
1) Replace all carbon comp resistors with metal films. A resistor from the filtering section literally blow up on a rehearsal, decided to change all of them.
2) Replaced all pots with new CTS, with switches when needed. The Volume 1 pot (Input Gain) hummed like crazy at high level setting but stopped humming when reaching 10. This was indicative that the problem was on the pot.
3) Changed the diode that gets the DC voltage for the relay with a diode bridge. The relay made a loud treble hum when activated (clean channel) due to the fact that the DC voltage was not really DC but had a big AC component.
4) Changed the relays with new ones, this helps to reduce the loud pop when changing channels. I still get a pop, at a much lower level thou. Still, I think something can be improved here.
5) Very important, grounding reorganization. Pots, cathode and filter capacitor share the same ground bus on the preamp board. This introduced a loud bass hum.
a) Pots are grounded on a separate part of the chassis. I just used a hole near by and used an screw that fitted there to attach a soldering point for the ground.
b) Left the ground points from the cathodes of the preamp tubes are on the ground bus.
c) Preamp filter capacitor is now grounded on the same ground of the rest of the filter capacitors. This is the responsible for most of the loud bass hum.
6) Heater voltage on the preamp, replaced it with a twisted pair of cables. The heater voltage runs on two separated bus on each side of the board. This can introduce mayor hum on the cables near by. To prevent this I replaced this bus with a twisted pair where the noise from one cable cancels the hum from the other.
To do this mods I had to cut some of the board bus and this was a major decision for me. But do not regret it, now the hum level is extremely low for a 33 year old high gain combo.
Hope you find this helpful!
(Ps: I originally posted this on the Mark IIB topic, but I think it makes much more sense to post it here)
The old logo with the grey shade that TiPimods shows is the original logo that came with the Mark I.
As far as I know:
- Mark IIs (A; B; C and C+) came with the bright Alu logo
- Mark IIIs came with the long Mesa/Boogie logo
- Mark IV were shipped with the blue Alu logo
Please keep in mind that Mesa has been always getting rid of any inventory of old parts so there could be some overlap in the early Mark III production.
Best regards
As far as I know:
- Mark IIs (A; B; C and C+) came with the bright Alu logo
- Mark IIIs came with the long Mesa/Boogie logo
- Mark IV were shipped with the blue Alu logo
Please keep in mind that Mesa has been always getting rid of any inventory of old parts so there could be some overlap in the early Mark III production.
Best regards
A better description would be:
- cream Boogie logo (with grey shade): Mark I and Mark I reissue
- grey Boogie logo (bright): Mark II
- cream Mesa/Boogie logo: Mark III
- grey Boogie logo (bluish): Mark IVa
- die cast Boogie logo (embossed): Mark IVb and Mark V
Yet, my black stripe Mark III came from factory with the grey Boogie logo.
Kind regards
- cream Boogie logo (with grey shade): Mark I and Mark I reissue
- grey Boogie logo (bright): Mark II
- cream Mesa/Boogie logo: Mark III
- grey Boogie logo (bluish): Mark IVa
- die cast Boogie logo (embossed): Mark IVb and Mark V
Yet, my black stripe Mark III came from factory with the grey Boogie logo.
Kind regards
Hello and sorry for digging out this old thread. It seems this thread and also mark2boogie's topic on the Mark IIB hold a ton of useful information. Unfortunately most of the pictures and documents that were uploaded on these topics are not available anymore. I would LOVE to see those documents and what mark2boogie modded on his Mark amps. I already sent him a private message a few weeks ago but he never got back to me.
I recently bought a MkIIA 60/100 (late 1978) with Reverb and GEQ which is a great amp. I've already replaced the old filter caps and modded the reverb to significantly decrease the noise but I would like to see what else could be done and learn about those other amps through it. I'm thinking about re-organizing the grounding-scheme or switching circuitry, all mainly to reduce hum (which is not too bad already). I have ideas how to do all this but would like to learn from the experience others have made.
So to conclude: Does anyone still has access to all those photos and documents in which mark2boogie documented the mods he did? I'm mainly interested in the Mark IIA but those files related to the Mark IIB would also be very interesting for me. I'd be so glad if somebody would send them to me via e-mail or upload them again here. Or maybe point me to where I can still find them online?
Thanks a lot and sorry for being a little late to the game.
I recently bought a MkIIA 60/100 (late 1978) with Reverb and GEQ which is a great amp. I've already replaced the old filter caps and modded the reverb to significantly decrease the noise but I would like to see what else could be done and learn about those other amps through it. I'm thinking about re-organizing the grounding-scheme or switching circuitry, all mainly to reduce hum (which is not too bad already). I have ideas how to do all this but would like to learn from the experience others have made.
So to conclude: Does anyone still has access to all those photos and documents in which mark2boogie documented the mods he did? I'm mainly interested in the Mark IIA but those files related to the Mark IIB would also be very interesting for me. I'd be so glad if somebody would send them to me via e-mail or upload them again here. Or maybe point me to where I can still find them online?
Thanks a lot and sorry for being a little late to the game.
