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  • #91
    I wonder what it would take to convert the V8 to accept 2 Phono jacks (stereo input) and output in stereo to a stereo external cabinet? Some of my pedals have stereo effects, which I currently can only use with 2 separate amps... one for each channel.



    Am I dreaming?

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    • #92






      Quote Originally Posted by gnolivos
      View Post

      Verne:



      From quick research, it appears that using higher ohm speakers is OK (i.e., running 8 ohm speakers on a 4 ohm amp).



      The real risk is to do the opposite (run 4 ohm speakers on a 8 ohm amp).



      Now, the downside of running 8ohm speakers on the Palomino (instead of 4 ohm) is that the output is reduced -- lower overall volume... did you experience this?




      No. This amp has balls to spare driving a 4 or 8 ohm load.



      Generally speaking unity gain is the main issue - that is - driving the impedance down to 0 [zero]. The closer to unity gain you get, the higher the frequencies become [which will alter the tone] and the hotter the transformer becomes because the load you're pushing through it. On these amps the risk is the transformer gets so hot the windings will melt requiring a new transformer.



      Since the amp/transformer was designed for an 8 ohm load and SLM saw fit to equip it with a 4 ohm speaker from the factory, I think we're safe running either load. The tone may change somewhat, so let your ears be your guide. For balls out wide open raunch, I find it's really tight driving 2 x 8's for 4 ohms.









      Quote Originally Posted by gnolivos
      View Post

      Somthing interesting I found on the V508, quoting from another source:



      "Here is how I got the purest power-tube saturation tone: Compressor, EQ for bass cut, huge increase in signal level without any distortion, guitar cable plugged halfway into the headphone jack so that I'm going into the FX return thus bypassing the Crate preamp entirely and going straight to the power tubes. Turn the crate volume up all the way. You definitely hear power tube saturation this way. "




      The way the V8 signal chain goes is:



      input->opamp 1 for first preamplification->opamp2 connected to the gain knob for increasing the signal to the->first 1/2 of the 12AX/T7->through the tone stack->volume control->fx send->fx return->second 1/2 of the 12AX/T7->EL84->output transformer->speaker.



      So what they're doing is bypassing everything before the second 1/2 of the 12AX/T7->EL84 and most of the OD is likely coming from the 12AX/T7. The volume control would have no effect in this type of a configuration.



      It's best to think of the opamp/gain on the V8 like a built in tube-screamer. I have some old JRC chips that were used in the original TS and have been tempted to drop them in to see what they do to the tone.



      Another mod I want to try is putting a switch so I can bypass the second opamp stage - the one connected to the gain knob. Theoretically this should turn the V8 into a quasi-2 channel amp. In order for it to be worthwhile it would have to be footswitchable, so I'm currently noodling on how to implement a relay switching circuit. Anybody with relay experience, feel free to chime in.









      Quote Originally Posted by John Watt
      View Post

      Verne Andru! You're apologizing to me about raunching out on me. Why? I said the graphics are beautiful also.

      It was you getting into your playing I was referring to, and you were using distorted tones.

      After the almost electronic treatise you've been posting here, it was surprising to hear you get a little nasty.




      LOL - I misread. Belated thanks.









      Quote Originally Posted by gnolivos
      View Post

      I wonder what it would take to convert the V8 to accept 2 Phono jacks (stereo input) and output in stereo to a stereo external cabinet? Some of my pedals have stereo effects, which I currently can only use with 2 separate amps... one for each channel.



      Am I dreaming?




      Yes, you're dreaming. You need 2 distinct amps, or an amp with 2 amps built in like a Roland chorus [name escapes me at the moment].



      I did manage to snag another V8 and have run it in stereo with the other one. Sounds great!
      --------------------------------
      www.VerneAndru.com

      Comment


      • #93
        Is there any reason I shouldn't shield the inside of the back panel? This is the part that covers the wiring, resistors and caps. It's just a piece of wood covered in an amp tolex type material. The tolex doesn't even cover the whole inner part. I noticed on my Marshall when I pulled the head out of it's casing, there is a metal sheet on the bottom which would be covering the same stuff - caps, etc.



        I've got some copper tape around, thought I'd ask.

        Comment


        • #94






          Quote Originally Posted by Matter-Eater Lad
          View Post

          Is there any reason I shouldn't shield the inside of the back panel?




          Nope. Not sure what you hope to accomplish. Be sure you don't end up shorting something in the process is all.
          --------------------------------
          www.VerneAndru.com

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          • #95
            Shouldn't the electronics be shielded? You ask what I want to accomlish. I just assumed electronics should be enclosed in metal, like the Marshall example I gave or a guitar cavity. If it's not needed, I won't do it.

            Comment


            • #96






              Quote Originally Posted by Matter-Eater Lad
              View Post

              Shouldn't the electronics be shielded? You ask what I want to accomlish. I just assumed electronics should be enclosed in metal, like the Marshall example I gave or a guitar cavity. If it's not needed, I won't do it.




              It depends on the electronics build and exposure to interference. Devices made with components in a point-to-point configuration where leads are exposed can pick up electronic and radio interference which can be mitigated by shielding the enclosure they are mounted in. Generally speaking, in modern PCB builds like the V8, there are not many components with exposed leads so the likelihood of issues like external hum, radio signals, etc. being picked up and amplified are significantly less. Marshalls, while they are predominantly PCB these days, still have a number of components with exposed leads but I think legacy probably plays a part in the decision as well.
              --------------------------------
              www.VerneAndru.com

              Comment


              • #97
                Got new tubes in the mail today... put them both in my V8, and I get a strange rattle noise when I hit certain notes. Put old tubes back, no noise.



                Finally found out the new EL84 is causing the issue. Is this normal?



                I used to have a V32, and it had that exact rattle! A local shop fixed it under warranty, and they told me they changed the tubes among other things...

                Comment


                • #98
                  Not sure about "normal" but it happens. I had a tube go microphonic on me for no apparent reason. Like any other manufactured device, the odd lemon happens. Glad you tracked it down. I hope the seller will make good on it for you.
                  --------------------------------
                  www.VerneAndru.com

                  Comment


                  • #99
                    Eurotubes is supposed to be top notch. I'm awaiting a response...



                    EDIT: Bob claims this is normal for combo amps... turns out 50% chance a tube will rattle. Im sending this one back, and he will send me another to see if I get lucky.

                    Comment


                    • Has anyone driven 2x12" speakers with this amp? I'm building a head and cabinet for it... wondering if this is a stupid idea.

                      Comment








                      • Quote Originally Posted by gnolivos
                        View Post

                        Has anyone driven 2x12" speakers with this amp? I'm building a head and cabinet for it... wondering if this is a stupid idea.




                        2 - 12's driven by a 5 watt tube amp is great! I like to mix the speakers. To keep to 8 ohms, I use 2 16 ohm speakers in parallel.

                        Comment








                        • Quote Originally Posted by gnolivos
                          View Post

                          Has anyone driven 2x12" speakers with this amp? I'm building a head and cabinet for it... wondering if this is a stupid idea.




                          Sounds HUGE through my Genz-Benz G-Flex 212 @ 4 ohms!
                          --------------------------------
                          www.VerneAndru.com

                          Comment


                          • Awesome... I'm debating what speakers to use, been wanting Celestion Greenbacks, but may try cheaper alternatives/clones such as WGS brand.



                            I have decided to get 2x12" at 8 ohm each. This way I can use one speaker @ 8 ohm (which from this thread I understand the V8 can handle), or I can run them both in parallel at 4 ohm (which I *know* the V8 can handle).



                            I plan to put a switch on the cabinet to drive one speaker, the other speaker, or both. I may have 2 different types of speakers in there, so this way I can experiment with the voicing combos... [anyone know what wiring diagram + switch would work?]



                            Little worried about switching from 4 ohm to 8 ohm loads though... am I going to mess up my amp head with this?!



                            I will post pics here of the completed head/cabinet in a bout 2-3 weeks. It will look like a mini-JTM45

                            Comment


                            • I look forward to it gnolivos. Are you doing the carpentry yourself?
                              --------------------------------
                              www.VerneAndru.com

                              Comment








                              • Quote Originally Posted by gnolivos
                                View Post

                                I plan to put a switch on the cabinet to drive one speaker, the other speaker, or both. I may have 2 different types of speakers in there, so this way I can experiment with the voicing combos... [anyone know what wiring diagram + switch would work?]




                                I believe Mojotone.com sells connector plates for cabinets that are prewired for stuff like that.









                                Quote Originally Posted by gnolivos
                                View Post

                                Little worried about switching from 4 ohm to 8 ohm loads though... am I going to mess up my amp head with this?!




                                Nope. I do it all the time with no issues. Trick is to be quick about it.
                                --------------------------------
                                www.VerneAndru.com

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