Early Mark 1

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DC3 Gridlock

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Picked this up last weekend. I believe it is an early to mid ‘70s Mark 1. It’s either in a re-tolex’d cab or a newer cab.

I’m guessing 100/60 watts with a Boost/Normal switch and Reverb. Probably the best sounding Boogie that I’ve owned.

IMG_3138.jpeg
 
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I would love to see gut shots of it. If that’s not too much to ask. I don’t think the handle is original.

Regards

Mark
Hi Mark, thanks for responding. I’ll try to pull the chassis this week and get some photos.

I believe the cab has been redone, I would like to restore it back to original as much as possible.
 
Hi Mark, thanks for responding. I’ll try to pull the chassis this week and get some photos.

I believe the cab has been redone, I would like to restore it back to original as much as possible.
I would appreciate that as there isn’t a lot of information about on the different circuits used on the Mark 1 Boogies.

Regards

Mark
 
Are you looking for schematic? The early Mark I had the Bassman/Marshall style presence that added high harmonic content in the power amp feedback loop, where the re-issue had the black Face side of things with a hi roll off presence at the end of the preamp before the phase inverter/poweramp next to the Master volume, all the way up is straight blackface, turned down is darker. Interesting side note, Carlos Santana's #009? had no cascaded gain stage like the later Vol. 1 and Vol. 2, it had volume treble, middle, bass, presence. Preamp boost was by disconnecting the Middle control lug that goes to ground for the boost, basically bypassing the the tone stack controls, the treble was somewhat still active. Later a 100k resistor was put across a push/pull pot, when pulled the 100k resistor was the amount of resistance between the tone controls to ground, allowing more signal to pass, pretty much bypassing the tone controls, when pushed in, the 10k Middle pot limited the gain and the tone stack worked normally. Today we see Mesa on on amps implements a 100k audio taper (LOG) pot so that from 0-12 O'clock its a normal Middle control, 12 O'clock to 5 is a variable boost control like on the Mark V 25, 35 and possibly other models. I been doing this before they started, when I learned about how their Preamp boost worked early on but the downside sometimes is that when its really boosted, the low notes get bloaty, farty, muddy, so one has to to carefully dial in and play lighter on low notes or turn the guitars volume down a bit to avoid the farts. Probably not what you wanted to hear, but most people are not aware of this. At lower settings the Mark I can get some killer Blues/Rock tones, it's basically a Twin with an extra Gain stage. Even without the extra gain stage, using the Preamp boost or swapping out the 10k Middle pot with a 100k Audio pot allows you to get some good early Santana like lead tones, even on a Fender amp with this mod. If you want schematics, we can help you with that too.
 
Are you looking for schematic? The early Mark I had the Bassman/Marshall style presence that added high harmonic content in the power amp feedback loop, where the re-issue had the black Face side of things with a hi roll off presence at the end of the preamp before the phase inverter/poweramp next to the Master volume, all the way up is straight blackface, turned down is darker. Interesting side note, Carlos Santana's #009? had no cascaded gain stage like the later Vol. 1 and Vol. 2, it had volume treble, middle, bass, presence. Preamp boost was by disconnecting the Middle control lug that goes to ground for the boost, basically bypassing the the tone stack controls, the treble was somewhat still active. Later a 100k resistor was put across a push/pull pot, when pulled the 100k resistor was the amount of resistance between the tone controls to ground, allowing more signal to pass, pretty much bypassing the tone controls, when pushed in, the 10k Middle pot limited the gain and the tone stack worked normally. Today we see Mesa on on amps implements a 100k audio taper (LOG) pot so that from 0-12 O'clock its a normal Middle control, 12 O'clock to 5 is a variable boost control like on the Mark V 25, 35 and possibly other models. I been doing this before they started, when I learned about how their Preamp boost worked early on but the downside sometimes is that when its really boosted, the low notes get bloaty, farty, muddy, so one has to to carefully dial in and play lighter on low notes or turn the guitars volume down a bit to avoid the farts. Probably not what you wanted to hear, but most people are not aware of this. At lower settings the Mark I can get some killer Blues/Rock tones, it's basically a Twin with an extra Gain stage. Even without the extra gain stage, using the Preamp boost or swapping out the 10k Middle pot with a 100k Audio pot allows you to get some good early Santana like lead tones, even on a Fender amp with this mod. If you want schematics, we can help you with that too.
Thanks for the great information. Schematics would be great.

The is at my tech currently for a checkup.

I appreciate the help.
 
Are you looking for schematic? The early Mark I had the Bassman/Marshall style presence that added high harmonic content in the power amp feedback loop, where the re-issue had the black Face side of things with a hi roll off presence at the end of the preamp before the phase inverter/poweramp next to the Master volume, all the way up is straight blackface, turned down is darker. Interesting side note, Carlos Santana's #009? had no cascaded gain stage like the later Vol. 1 and Vol. 2, it had volume treble, middle, bass, presence. Preamp boost was by disconnecting the Middle control lug that goes to ground for the boost, basically bypassing the the tone stack controls, the treble was somewhat still active. Later a 100k resistor was put across a push/pull pot, when pulled the 100k resistor was the amount of resistance between the tone controls to ground, allowing more signal to pass, pretty much bypassing the tone controls, when pushed in, the 10k Middle pot limited the gain and the tone stack worked normally. Today we see Mesa on on amps implements a 100k audio taper (LOG) pot so that from 0-12 O'clock its a normal Middle control, 12 O'clock to 5 is a variable boost control like on the Mark V 25, 35 and possibly other models. I been doing this before they started, when I learned about how their Preamp boost worked early on but the downside sometimes is that when its really boosted, the low notes get bloaty, farty, muddy, so one has to to carefully dial in and play lighter on low notes or turn the guitars volume down a bit to avoid the farts. Probably not what you wanted to hear, but most people are not aware of this. At lower settings the Mark I can get some killer Blues/Rock tones, it's basically a Twin with an extra Gain stage. Even without the extra gain stage, using the Preamp boost or swapping out the 10k Middle pot with a 100k Audio pot allows you to get some good early Santana like lead tones, even on a Fender amp with this mod. If you want schematics, we can help you with that too.
The P.I. stage seems to vary in Mark 1 amps. It’s either the tweed Bassman style or the blackface Fender style P.I. stage. I wonder why there was such variation.
The tweed Bassman circuit does have more gain than the blackface style circuit. It would be good to hear a recording of both amp types in an A/B test, though I think there isn’t sufficient interest.

Regards

Mark
 
The P.I. stage seems to vary in Mark 1 amps. It’s either the tweed Bassman style or the blackface Fender style P.I. stage. I wonder why there was such variation.
The tweed Bassman circuit does have more gain than the blackface style circuit. It would be good to hear a recording of both amp types in an A/B test, though I think there isn’t sufficient interest.

Regards

Mark
This amp has pretty low gain.

I realized it has a push-pull knob on Volume 2. Not sure what it does, maybe a bright switch, but I really don’t hear much difference with it pulled or pushed in.
 
No mids control. I'd love to see a gut shot.
It’s most unusual. You won’t know what is going on without looking inside. The amps the tweed P.I. typically have a stack of gain, much more that the Blackface style P.I. stage.

In the case of the amp pictured there could be many reasons for low gain. The Fetron could be shot etc.

Regards

Mark
 
I find it hard to work out how the circuit progressed over time. I thought your amp would have had the tweed Bassman P.I. stage, but as far as I can tell it’s more like a Blackface circuit. Who did you talk to at Boogie?
As far as I can tell there are no accurate records of these early amps. They can sound quite different depending on which P.I. stage they decided to use.
I noticed that it doesn’t have the resistor on the plate of one of the output valves and the wire being wrapped around shielded cable wires.

Regards

Mark
 

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