Half a Major Build
Moderators: pompeiisneaks, Colossal
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- Posts: 478
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- Location: Southern California
Half a Major Build
Someone commissioned this from me and I forgot to post it. It also had a switchable 1 wire cascade mod. I used the Classictone/Dynaco Clone PT and OT to give about 565+ on the plates of the two KT88's.
[img2448]http://i.imgur.com/9nzahbK.jpg[/img]
[img2448]http://i.imgur.com/Gup41iS.jpg[/img]
[img2448]http://i.imgur.com/NtFcSik.jpg[/img]
[img3264]http://i.imgur.com/om4fheo.jpg[/img]
[img2448]http://i.imgur.com/NjlvtTm.jpg[/img]
[img3264]http://i.imgur.com/Z6IegfI.jpg[/img]
And a clip:
https://www.youtube.com/watch?v=aBADx0TlrCI
[img2448]http://i.imgur.com/9nzahbK.jpg[/img]
[img2448]http://i.imgur.com/Gup41iS.jpg[/img]
[img2448]http://i.imgur.com/NtFcSik.jpg[/img]
[img3264]http://i.imgur.com/om4fheo.jpg[/img]
[img2448]http://i.imgur.com/NjlvtTm.jpg[/img]
[img3264]http://i.imgur.com/Z6IegfI.jpg[/img]
And a clip:
https://www.youtube.com/watch?v=aBADx0TlrCI
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- Posts: 1675
- Joined: Thu Oct 06, 2016 5:53 am
Re: Half a Major Build
Nice!! Thanks for sharing
How does it compare to the 200watt original monster sound wise
How does it compare to the 200watt original monster sound wise
Re: Half a Major Build
Nice neat wiring, I like how you did the heaters . Sounds great
db
db
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- Posts: 478
- Joined: Thu Nov 01, 2007 4:42 am
- Location: Southern California
Re: Half a Major Build
It has the tone without the bone crushing loudness. But if I were building one for myself, I would do the 4 KT88 version but with the lower 560 or so B+ just to get the full effect....Bombacaototal wrote:Nice!! Thanks for sharing
How does it compare to the 200watt original monster sound wise
Learning to learn...
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- Posts: 478
- Joined: Thu Nov 01, 2007 4:42 am
- Location: Southern California
Re: Half a Major Build
Merlin Blencowe style. I do that with all my amps now...v846 wrote:Nice neat wiring, I like how you did the heaters . Sounds great
db
Learning to learn...
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Re: Half a Major Build
That's a good idea. How many watts would that be? I think one would even be able to fit the circuit on a smaller size head for better transportabilityfusionbear wrote:It has the tone without the bone crushing loudness. But if I were building one for myself, I would do the 4 KT88 version but with the lower 560 or so B+ just to get the full effect....Bombacaototal wrote:Nice!! Thanks for sharing
How does it compare to the 200watt original monster sound wise
Do you have the schematic/ layout you used by any chance
Re: Half a Major Build
Another nice one Bear. Well done.
Someone is getting a great gigging rig - it looks very robust.
I don't know why, but I avoid building anything with a B+ higher than 500v.
Maybe soon. Hmmm.
Someone is getting a great gigging rig - it looks very robust.
I don't know why, but I avoid building anything with a B+ higher than 500v.
Maybe soon. Hmmm.
Why Aye Man
- martin manning
- Posts: 13365
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Re: Half a Major Build
Very neat, and good idea to use the Dynaclone transformer set. BTW, which model Classic Tone transformers did you use? A-431S OT and P-782S PT?
If it's a half-Major, I guess you have to call it a Warrant Officer?
If it's a half-Major, I guess you have to call it a Warrant Officer?
Re: Half a Major Build
Interesting, have you noticed a reduction in heater hum compared to the loop around the socket wiring used in old Marshalls?fusionbear wrote:Merlin Blencowe style. I do that with all my amps now...v846 wrote:Nice neat wiring, I like how you did the heaters . Sounds great
db
Thanks,
David
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- Posts: 478
- Joined: Thu Nov 01, 2007 4:42 am
- Location: Southern California
Re: Half a Major Build
Yep... that set.martin manning wrote:Very neat, and good idea to use the Dynaclone transformer set. BTW, which model Classic Tone transformers did you use? A-431S OT and P-782S PT?
If it's a half-Major, I guess you have to call it a Warrant Officer?
Learning to learn...
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- Posts: 478
- Joined: Thu Nov 01, 2007 4:42 am
- Location: Southern California
Re: Half a Major Build
It is very slight, but my amps are quiet anyway due to using good grounding points to begin with.v846 wrote:Interesting, have you noticed a reduction in heater hum compared to the loop around the socket wiring used in old Marshalls?fusionbear wrote:Merlin Blencowe style. I do that with all my amps now...v846 wrote:Nice neat wiring, I like how you did the heaters . Sounds great
db
Thanks,
David
Learning to learn...
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- Posts: 478
- Joined: Thu Nov 01, 2007 4:42 am
- Location: Southern California
Re: Half a Major Build
It is about 90 watts. As for a schematic, I didn't draw one. I used the original PA version of the Major as a starting point. I also lowered the first stage filter caps to 250uf each in series since this is only for two KT88's. The PT requires half wave rectification like a 50 watt type Marshall PT, so I had to adjust the circuit there.I used a 500pf bright cap on the Bright channel and used a 500pf across the mixer. The tone stack is Bass spec with the exception of a 47k slope resistor. I experimented with layouts on the turret board until I discovered what would work best. You can see some changes in the pictures I posted. Also, it is using the so called "Rich mod" PPIMV dual 500k PEC pot. I like this PPIMV on this amp because it lets you bring up the volume more slowly. Also, because it kills the negative feedback at lower settings, it lets you get that looser VH1 feel with the cascade mod on. In order to do the cascade mod properly, I used a .0022 coupling cap on the normal channel. You plug into that channel if you want to cascade. I also used a 100uf cathode bypass cap on the shared cathodes of V1. I played around with several values as low as 10uf to as high as 330uf but, the 100uf seemed to give the best overall results.Bombacaototal wrote:That's a good idea. How many watts would that be? I think one would even be able to fit the circuit on a smaller size head for better transportabilityfusionbear wrote:It has the tone without the bone crushing loudness. But if I were building one for myself, I would do the 4 KT88 version but with the lower 560 or so B+ just to get the full effect....Bombacaototal wrote:Nice!! Thanks for sharing
How does it compare to the 200watt original monster sound wise
Do you have the schematic/ layout you used by any chance