Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: 2deaf on February 13, 2018, 11:09:19 pm
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Pretty much the same as the last one except I used a MOSFET vibrato and then used the vibrato tube for an effects loop. The loop uses LNF to obtain the low impedance send, and as long as I was at it I used LNF on the return also. The levels are virtually identical whether the loop is bypassed or not and I actually prefer the sound of the amp when the loop isn't bypassed. I haven't taken it down to the studio yet to try it at higher volumes, but it sounds good (to me) at residential levels.
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I used a DeLuxe chassis this time (Thanks again, Doug). It's another rat's nest, but that is what I do. I started with Fender and I guess I will never break the habit.
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More pictures
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That is not a rats next. And you got me with the blond cab.
I have been wanting to try a different mosfet loop. Do effects have good response with this loop and can you use rack and pedals equally or
Either or?
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Looks great and lots of interesting stuff in the circuit.
If you don't mind i have few questions:
How does the switching in the second tone stack affect the sound?
And how would you compare the loop send stage with lnf to cathode follower stage that is usually used in fx-loops?
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very nice. but kind of crowded, no?
--pete
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Do effects have good response with this loop and can you use rack and pedals equally or
Either or?
The Send puts out a maximum of 3.3dBu, which is great for professional line-level gear but a little hot for a lot of stomp boxes. I know some of the MXR stomp boxes are good up to 5dBu, so they they would work fine. I don't actually own any stomp boxes so I borrowed an old Ibanez Stereo Chorus and tried it. It works fine at clean settings, but it starts clipping if I turn the amp up too much. I tried it through a couple of rack-mounted multi-effects units and it works great. If I had put a send level control on it, it would have worked for both. I think you could consider this a line-level use loop.
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And how would you compare the loop send stage with lnf to cathode follower stage that is usually used in fx-loops?
Anything the LNF send can do, the cathode follower send can also do if designed properly. Plus you can get a lower output impedance from a CF. I calculated the LNF output impedance at 8.1K, which is plausible because it has no problem driving a 10K load. It will also drive a .001uF capacitor out beyond 17KHz before it drops 1dB, so it won't have any high-end loss with a 33 foot cable. They are both exceptionally clean drivers with all that negative feedback.
I designed the LNF loop a while ago and never had an occasion to try it in an actual amp. That's the main reason I put it in this amp.
How does the switching in the second tone stack affect the sound?
Radically.
In the attached possible tone stacks, the upper left is the standard Fender TS that I use for clean Fender sounds. The lower right TS is the one I use for heavily overdriven settings. It allows me to add some thickness to the sound without adding muddying bass.
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. . . but kind of crowded, no?
That's the way I felt about it after a couple of days wiring it up.
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"Pretty much the same as the last one"
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Is there a thread for the last one?
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http://el34world.com/Forum/index.php?topic=22432.msg239318#msg239318
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Radically.
In the attached possible tone stacks, the upper left is the standard Fender TS that I use for clean Fender sounds. The lower right TS is the one I use for heavily overdriven settings. It allows me to add some thickness to the sound without adding muddying bass.
Thanks. I put the values on tone-stack calculator and i see what you mean.
You must have put lot of thought to get that result with so few added components and with a simple switch.
Kudos to you