So I built this some time ago which is basically a Mullard 5-10 with a few non-significant modifications like a 5y3 instead of EZ80, and a 6sj7 instead of EF86, although it was first built with the EF86 now I have added and rewired the socket for the 6sj7. Also is important to mention I have not added the tone stack, everything else is as the original schematic.
What are your suggestions if I want to plug a guitar with volume and tone controls, I was thinking using the spare 9 pin socket adding a single "high mu" triode for input --> tone-stack / volmue --> 6sj7 .
the 6sj7 as it is already has lots of gain.
An externally hosted image should be here but it was not working when we last tested it.
What are your suggestions if I want to plug a guitar with volume and tone controls, I was thinking using the spare 9 pin socket adding a single "high mu" triode for input --> tone-stack / volmue --> 6sj7 .
the 6sj7 as it is already has lots of gain.
The sensitivity with those is something like 10mV with the feedback circuit disconnected, I would play through it with the feedback disconnected first before doing anything.
After you try that there is the free noval socket you have so you could do a high mu dual triode: gain stage direct coupled to cathode follower-->tonestack/volume-->6sj7.......
After you try that there is the free noval socket you have so you could do a high mu dual triode: gain stage direct coupled to cathode follower-->tonestack/volume-->6sj7.......
good tip, I will try that, I didn't think of a cathode follower but it's a very good idea, similar to what the did with this
When I disconnect the feedback it get really noisy, hum mostly and sometimes it oscilates, so perhaps I will add a pot to reduce/increase the feedback as a feature.
Thank you.
When I disconnect the feedback it get really noisy, hum mostly and sometimes it oscilates, so perhaps I will add a pot to reduce/increase the feedback as a feature.
Thank you.
So unstable with no feedback........Mullard does use quite a bit of feedback at 26db, maybe cut it back to 10db.
That circuit has a lot of gain even with the feedback. I was wrong earlier, the amp has an input sensitivity of 40mv WITH the feedback...........cut the feedback down to 10db and it should be a work for guitar
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The 5-10 does not have quite enough overall gain for guitar. But all you would need to add is a single triode gain stage like the first gain stage of any Fender or Marshall amp. If you look in Mullard's circuit book, you will find two versions of the 5-10 amp. One is a straight power amp while the other adds a tone control and volume control circuit to the input. Mullard's tone control setup is optimized for hifi use so using something like a Fender tone stack woudld work better for guitar. You could place it between output of the added triode input gain stage and the EF86's grid for the 5-10. The 5-10 can have the EL84's either pentode connected or ultralinear. Pentode would probably offer a more classic sound for guitar. The amp is capable of a lot more then 10 watts. The 10 watt rating is for very low distortion hifi specs. Most guitar amps are rated at distortion levels as high as 5%. The 5-10 is capable of 15 watts before really heavy clipping. Glad to see someone else using these classic Mullard circuits.
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