Marshall '68 bass thoughts

Rasmusr

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Hey everyone. I checked my history and my only other previous thread is inquiring about a '68 Marshall which I got great help with at the time. Funny how I'm still on that same path trying to find a good specimen locally, although very passively. This is in essence a clone of my previous thread even to the year of the amp in question, but this time the amp for sale seems to be in much better shape, which is reflected in the price.

The seller is asking 3900 €. The information I have is that the unit is a '68 small box 50W bass. It's had a "bright cap-mod" and "split cathode-mod" done to it according to the seller in essence converting it to a lead spec according to him. The output tranny is described as an original and the power tranny to be a Drake no. 1202 216, assumed to be replaced sometime many decades ago.

Still got the vintage Marshall bug and I've been using a 1987x and a 2525h since 2018 along with a BF Fender. Honestly the Jubilee I find to be underwhelming and I mostly play my Fender. The 1987x is sold some time ago. Still my favourite Marshall I've had has been the 2061x.. I'd like an older head for recording purposes mainly.

Does this seem original and in good shape? I'm not really too fussed about originality as, but it's all in relation to the asking price of course. Again, much appreciated for the insights.

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neikeel

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Looks like a 68 Bass amp to me
The PT is from a Carlsbro
I'd tidy it up back to stock with new bias caps etc
It is not bad but only you can decide on price.
 

TAZIN

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A side from the mains tx being changed I also noticed the following:
Indicator light.
All three 1 Meg potentiometers.
The three power supply filter caps.
The one bias filter cap & the bias circuit diode. Also updated with a trimmer pot.
The rectifier diodes; along with being relocated due to a mains tx change.
The Bulgin socket for the power cord.
A new cathode bypass cap for V1a.
A rather shoddy install for the split-cathode for V1b.
Added 1K/5w screen/grid resistors on output valve sockets.
At least one octal socket has been changed.
The Standby switch has been changed.
 

junk notes

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Serial # 11 series, early 68?
 
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junk notes

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It's had a "bright cap-mod" and "split cathode-mod" done to it according to the seller in essence converting it to a lead spec according to him.
ahh I see. okay cool.
 

neikeel

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A side from the mains tx being changed I also noticed the following:
Indicator light.
All three 1 Meg potentiometers.
The three power supply filter caps.
The one bias filter cap & the bias circuit diode. Also updated with a trimmer pot.
The rectifier diodes; along with being relocated due to a mains tx change.
The Bulgin socket for the power cord.
A new cathode bypass cap for V1a.
A rather shoddy install for the split-cathode for V1b.
Added 1K/5w screen/grid resistors on output valve sockets.
At least one octal socket has been changed.
The Standby switch has been changed.
Yes all the above, and the output jacks are replacements (presume scavenged as they were used pre 66, and the input jacks are new, both fuse holders are replacements (generic Belling-Lee vs the type used by Marshall in 68.
I wondered about the 1M pots (some shortages/weird variations around occasionally) but given the ground bus was chopped I agree.
It could be restored to original spec/parts save for the PT but that would make the asking price higher.
 

TAZIN

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Yes all the above, and the output jacks are replacements (presume scavenged as they were used pre 66, and the input jacks are new, both fuse holders are replacements (generic Belling-Lee vs the type used by Marshall in 68.
I wondered about the 1M pots (some shortages/weird variations around occasionally) but given the ground bus was chopped I agree.
It could be restored to original spec/parts save for the PT but that would make the asking price higher.
I checked through my files and I believe the input & output jacks are original since other builds around this time frame used them too. Anyhow, here's an example of the typical 1 meg potentiometer used as substitutes during this time. I can't remember the brand name off hand (Ohmite?)...I've got it written down somewhere in my notes though.

While true Marshall seemed to use the SMK fuse holders a lot during 1968 but, they did use the Belling-Lee on occasion too. My files reveal other amps built about the same time also using Belling-Lee's.
 

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Rasmusr

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Fantastic, thanks so much! Sorry for the response delay. Had some business to take care of.

While it seems there are quite a bit of modifications as per the lists of Neikeel and Tazin, I sense nothing all too critical has been altered in your opinion. I do have to say, as more of a player I’m not entirely sure of the criticality of all those small components that you guys mention (pots..) I know of course of the larger parts’ importance such as the transformers etc.

I do think the price is a bit high for an amp that has work done to it and I am in contact with the seller still regarding pricing. I am still interested in this. If I end up with this I’ll get some more gut shots for the forum to check out. Very much appreciated! Right now I just sold some more gear and I’ve got the cash burning my pocket so I’m looking to acquire a Marshall soon.

There just came up another ’70 amp which is a super bass. I’m a bit embarrassed to post another thread to milk more info from you guys after the helpfulness already but I think I’ll do it if for nothing else but to appreciate the good vintage 😄 thanks!
 

LoudStroud

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Aside from all of the minor repairs and changes made, it looks good. Although the power transformer change is not minor, but that was a good replacement transformer.

The commenter above who said it came from a Carlsboro is likely correct. Carlsboro amps ran a higher plate voltage, which if the case with that transformer would keep that Marshall accurate for a ‘68. I recently dropped an output transformer from the Carlsboro into my small box 50 watt and it sounds fantastic and original.

The split cathode mod would be considered a partial conversion, as the tone stack and phase inverter circuits are still original.

Overall, I would imagine this is a great sounding amp. As far as originality, yes I agree that there should be some negotiating room on that price, But these days the $$$ keep going up and up.
 


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