1967 Super Bass Build

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Danhalen
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1967 Super Bass Build

Post by Danhalen » Wed May 08, 2019 1:48 pm

Hey guys. I have been planning to build a '67 100 watter for years! Not sure why I haven't gotten around to it yet... Anyway, I am getting closer to making it happen. I am undecided whether to build a 10000 series amp, or a black flag amp.

So, here is my question. I have this whacky idea to have a switchable dual/single rectifier and switchable mains filtering (32uf and 50uf). I am still trying to figure out if this is worth the trouble. I love the 10000 series sound, to me it sounds like a JMP-family amp. The black flag has all that sag/fuzzy/ghosting type of stuff when cranked, but just a little more punchy than the 45/100 which I like. It has 'character' I think. I love 'em both. Maybe I will just end up choosing one...

I guess another way of looking at this would be: what is it about the black flag that seems to make it just a bit more stout/punchy than the 45/100 when it is cranked? Is it the dual rectifier (which is the largest obvious difference I think) or is it simply the EL34's and/or the lower impedance on the OT?

Anyone attempted making the single dual rectifier switchable? Roe, when I searched about this just now I see that you built a '67 with switchable mains filtering, so I guess you have done 50% of idea this already! And, I have to say that every clip I have heard of your stuff not only sounds great, you seem to gravitate towards the same type of tones as me (Malcolm Young semi-dirty and Cream-era Clapton on the more cranked up side).

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Re: 1967 Super Bass Build

Post by neikeel » Wed May 08, 2019 3:07 pm

Odd actually as my latest 45/100 (Hendrix/Dickinson spec) is very punchy and suitably cranked has plenty of gain for classic/heavy rock (not metal unless goosed with a pedal). For reference I have built x4 45/100s owned and restored several versions (KT66 and EL34) and owned/restored several 12 series and 69 plexi 100s.

I would suggest 10 series with 50 mains, just a single rectifier etc, good quality iron and take it from there, that is just my experience but you will probably need to do the voyage of discovery for yourself!
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Re: 1967 Super Bass Build

Post by Danhalen » Wed May 08, 2019 10:12 pm

Thanks Neil that is probably a good idea. If I was going to choose one, one consideration is that the 10000 is probably the closer of the two to my 50 watt 1986. That may be a reason to try the Black Flag arguably.

When you say that your latest 45/100 is very punchy, do you mean punchier than earlier versions that you have built/played? Do you have the lead tonestack and 32uf (dual 32uf?) preamp filtering? Or is it stock filtering? Because I find that very interesting. I guess I should be considering a 45/100 as well! :D.

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Re: 1967 Super Bass Build

Post by neikeel » Thu May 09, 2019 4:04 am

dual 32 in preamp (like the 10 series) lead tone stack (33k/500pF) extra 10k dropper between the preamp.

usual 45/100 power 32uF, 16 screens and 32 PI

Marstran iron, NOS Mullard ECC83s and GEC KT66
Neil

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Re: 1967 Super Bass Build

Post by Roe » Thu May 09, 2019 9:32 am

I like the following:
22+22uf preamp
32uf PI
16uf screens
33uf/50uf mains
Switchable mains works well for me. The rectifier or PT doesn't matter too much if it has the right vintage specs. 33uf is great for Cream, Free and blues. 50uf is much better for ac/dc
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Danhalen
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Re: 1967 Super Bass Build

Post by Danhalen » Thu May 09, 2019 11:58 am

Roe, that sounds awesome. It definitely would be easier to just build the single rectifier and leave it alone. For the switchable filtering, what configuration did you use?

I guess one way would be to switch between a pair of 100uf caps in series and a pair of dual 32uf caps in series? Or have the 4 32uf caps in series/parallel like the earlier amps and have a pair of dual 16uf caps in series that could be switched in and out (in parallel with the 4 mains caps). I guess that would be a lot of caps though!

I guess a 119 or 132 type transformer would work fine for this type of build.

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Re: 1967 Super Bass Build

Post by Roe » Fri May 10, 2019 3:17 am

Danhalen wrote:
Thu May 09, 2019 11:58 am
Roe, that sounds awesome. It definitely would be easier to just build the single rectifier and leave it alone. For the switchable filtering, what configuration did you use?

I guess one way would be to switch between a pair of 100uf caps in series and a pair of dual 32uf caps in series? Or have the 4 32uf caps in series/parallel like the earlier amps and have a pair of dual 16uf caps in series that could be switched in and out (in parallel with the 4 mains caps). I guess that would be a lot of caps though!

I guess a 119 or 132 type transformer would work fine for this type of build.
a 119 or 132 would be perfect. I'm using the BC vishay 450v axial caps, since they sound great. I have two 68uf caps in series for a total of 34uf that are always connected. Then I add two 33uf caps in series (= 16.5uf) in parallel to the 34uf for a total of 50uf. This works great BUT you do need power resistors across the switch. Metal oxide 2w resistors, at least 10k and less than 100k. For an example see the ac30 schematic that switches between 22 and 44uf. For the switch I am using the voltage selector that is already installed in the chassis, although I'm not using it as a voltage selector but as a filtering switch.

The amp is an early 67 jtm45/100 with el34s and the 1204-43 PT. The 235v wall voltage into the 240v secondaries gives 495v on the plates at idle, which is more than sufficient with a 1.7k OT (119) (still it does not redplate with RFTs/Siemens el34s). This amp blew a 130w speaker cab in one song (two 65w speakers were blown).
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Danhalen
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Re: 1967 Super Bass Build

Post by Danhalen » Fri May 10, 2019 1:56 pm

Roe wrote:
Fri May 10, 2019 3:17 am
a 119 or 132 would be perfect. I'm using the BC vishay 450v axial caps, since they sound great. I have two 68uf caps in series for a total of 34uf that are always connected. Then I add two 33uf caps in series (= 16.5uf) in parallel to the 34uf for a total of 50uf. This works great BUT you do need power resistors across the switch. Metal oxide 2w resistors, at least 10k and less than 100k. For an example see the ac30 schematic that switches between 22 and 44uf. For the switch I am using the voltage selector that is already installed in the chassis, although I'm not using it as a voltage selector but as a filtering switch.

The amp is an early 67 jtm45/100 with el34s and the 1204-43 PT. The 235v wall voltage into the 240v secondaries gives 495v on the plates at idle, which is more than sufficient with a 1.7k OT (119) (still it does not redplate with RFTs/Siemens el34s). This amp blew a 130w speaker cab in one song (two 65w speakers were blown).
Haha wow! Don't mess with the power of the '67! Do you run a full stack at all times with that amp now?

This is some really great info, thanks. I had not thought of using the pair of 68uf caps, that sounds like a great way to go for this setup. It's a great idea actually. I am actually thinking it would also be cool to try the same thing with a KT66 JTM 45/100 build as well. I'm sure one of those with the 50uf mains would sound quite a bit different than with 32uf.

Edited my post: I removed the question about preamp filtering. I found a thread with a quote from Greg Germino about the Dickinson spec, where he describes the difference the increased filtering makes in a JTM 45/100.

Very interesting... I am beginning to think that maybe the slight difference in tightness I am hearing between the Black Flag amps and JTM 45/100's has more to do with the increased preamp filtering than the different rectifier. Neil, your comment about the punchiness of the Dickinson spec seems to support this idea as well?

This is getting interesting. Neil and Roe thank you both for some great ideas to consider!

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Re: 1967 Super Bass Build

Post by Danhalen » Sun May 12, 2019 11:16 pm

Have you guys heard this amp: https://www.youtube.com/watch?v=U3miYqQEcU8 ?

He plays a Les Paul through the same amp in this video (but not the whole time) https://www.youtube.com/watch?v=H_okz-TXbds&t=39s

Looks like the PI filtering has been upped to 33uf (one cap removed), other filtering looks stock?

Wow. To me that sounds really amazing. That's exactly what I'm going for. If i can achieve something like that with the lower mains filtering setting I will be happy.

After pondering this build, and considering your excellent advice, here is what I am leaning towards starting with. I think I am getting closer to what I want to do! The next step, I think, will be to get a layout together.

-Black Flag power board layout, so I can experiment with rectifiers (voyage of discovery etc :D).
-Marstran or ****** 1202-132 OT (Roe, I was reading that you thought it was very similar to the 1202-119, but had just a bit less bass. I am almost certain that I will go with the 1202-132, rather than 1202-119).
-Marstran or ****** 1203-80 PT with the two secondaries, so I can experiment with dual rectifiers if I want.
-Mains filtering 33uf/50uf switchable a la Roe/Vox
-Screens filtering 16uf
-PI filtering 32uf
-Preamp filtering either dual 32 or dual 22
Last edited by Danhalen on Fri May 17, 2019 12:22 pm, edited 1 time in total.

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Re: 1967 Super Bass Build

Post by Roe » Wed May 15, 2019 9:13 am

Danhalen wrote:
Fri May 10, 2019 1:56 pm
...

Haha wow! Don't mess with the power of the '67! Do you run a full stack at all times with that amp now?
...
Usually its only one cab but I often add an attenuator though
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Re: 1967 Super Bass Build

Post by neikeel » Wed May 15, 2019 5:53 pm

Interesting clips.
I would have thought the 71 SL would be much brighter - mine was (but not sure where he EQ'd it)
When maxed out it is surprising how the SL and SB sound relatively similar
Of course the 67 SB is the same as a SL apart from a bright cap on the Vol 1 pot.
Neil

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Danhalen
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Re: 1967 Super Bass Build

Post by Danhalen » Sun May 19, 2019 11:42 am

neikeel wrote:
Wed May 15, 2019 5:53 pm
Interesting clips.
I would have thought the 71 SL would be much brighter - mine was (but not sure where he EQ'd it)
When maxed out it is surprising how the SL and SB sound relatively similar
Of course the 67 SB is the same as a SL apart from a bright cap on the Vol 1 pot.
Yeah good point. I wonder if that super lead has no bright cap? Or maybe it's just because it is cranked.

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Re: 1967 Super Bass Build

Post by kats » Tue May 21, 2019 1:16 am

Hi DanHalen!

Co-incidentally, I'm in the middle of a similar build that I put on hold almost a decade :D. Nothing much to offer other than friendly chit chat :) Late '67 build, Marstran xformers (1202-132/ 1203-80). 3H choke

I'm starting out filtering 100/100 mains, 32/32 screens, 32 PI, and 32+32 preamp. Shared cathode, single rectifier, 470k mix resistors, 27k on 16ohm NFB. Modern CF resistors except the long ones are CC, mustard signal caps. The only thing I'm humming and hawing about is the 2@ 1k5 or 4@ 5.6k grid stoppers (stupid, I know...) and I'm gonna start out by using the two voltage droppers (8.2k + 10K). I decided to use modern el34's, let's see how long I can control myself :). My last build was 10 years ago (JTM45) which I just love, but I've always been drawn to 100 watt amps so I went this route. I use an attenuator.

Oh yeah, I put a pull/push knob o the bright channel with a 5000pf cap.

The only thing is the xformer wait times are quite long - at least 5 weeks.

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Re: 1967 Super Bass Build

Post by kats » Tue May 21, 2019 1:43 am

Danhalen wrote:
Sun May 19, 2019 11:42 am
neikeel wrote:
Wed May 15, 2019 5:53 pm
Interesting clips.
I would have thought the 71 SL would be much brighter - mine was (but not sure where he EQ'd it)
When maxed out it is surprising how the SL and SB sound relatively similar
Of course the 67 SB is the same as a SL apart from a bright cap on the Vol 1 pot.
Yeah good point. I wonder if that super lead has no bright cap? Or maybe it's just because it is cranked.
Note that he must have these amps quite attenuated for that LDC not to be crapping out. So probably quite a bit of HF loss. He might be saturating the preamp as well. IIRC he might be using a Neve 1073 clone, and I know the real ones really fatten up and soften the high end, especially when pushed... i the room I would expect the differences to be quite a bit more dramatic.

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Re: 1967 Super Bass Build

Post by kats » Tue May 21, 2019 12:06 pm

neikeel wrote:
Wed May 08, 2019 3:07 pm
...my latest 45/100 (Hendrix/Dickinson spec) is very punchy and suitably cranked has plenty of gain for classic/heavy rock (not metal unless goosed with a pedal).
I can imagine myself loving that set up. Have you tried modern KT66's? I only have experience with GEC's and wouldn't want to waste money on a quad that would a) not last, b) not sound that great.

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