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Temp "Time Format" issue Fix in Discussions

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Author Topic: Chorus issues.  (Read 18855 times)

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rnolan

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Re: Chorus issues.
« Reply #60 on: Time Format »

Well we/you can make sure he got the schematics, they are all here although, lots of prior experience (and knowing MP-1s backwards) gives a major head start and a big save on troubleshooting time (eg MJMP).  My guy here in Canberra hasn't seen them either so I want to bring him up to speed.  First step is I'll take over a working MP-1 and MP-2 and melt him  >:D (he has a JCM800). But this will take time.

So you can buy a cheap scope and then try to sus it out, a good option IMO if you like to get under the hood  :dunno: .  The other best alternative IMHO is to send it MJMP and also get anything else done to it it needs. Postage will probably be around $200 there and back ? maybe less (they aren't particularly heavy). Not to piss in his pocket too much LoL, but MJMP does great work  :thumb-up: (he revamped both my MB-1s  :whoohoo!: ) and his prices are very reasonable (and elastic).  Unfortunately, the main ADA aware tech in Oz (Sid Barret) has (IIRC passed away), he used to do all the work on them for Pro Audio (Oz distributor), back when I did the guitar repairs for them...
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Studio Rig: MP2/MB1 > Eurorack UB2442FX-Pro > TC M-One XL > Behringer Truths (with Truth Sub) / QUAD ESL 63s
Live Rig: MP2/MB1 > Alesis Quadverb > Alesis Midiverb 4 > Yamaha AM802 > B200s/Carvin TS100/DCM200L > ADA Split Stacks/Mesa P112s

Richie_B

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Re: Chorus issues.
« Reply #61 on: Time Format »

Alrighty.... this just popped up for auction and its local. Any thoughts?

http://www.ebay.com.au/itm/20-MHz-Dual-Trace-Oscilloscope-/142239309700?hash=item211e1f9f84:g:iSkAAOSwEzxYc2h7
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Guitars: Fernandes ST 40, FST 125, Fernandes TEJ LTD ED and a Vortex. Chapman ML3 Pro Modern.

ADA MP1, ENGL E530, ENGL 840/50 Power amp, Carvin X100B, 2X12 cab.

Richie_B

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Re: Chorus issues.
« Reply #62 on: Time Format »

I was doing a bit more testing earlier. On patch 6 Clean with Compression,it does the clipping sound when it's on it's default chorus depth of 0.1. If I set the depth to 0, the sound is clean and unaffected. The same result happens when I have the depth on 0.1 but lower the master gain from 9.5 to about 7. All up, what I've noticed is that either by turning the chorus depth off or lowering the master gain, the result is no clipping. This is on any patch where the chorus is active, even distorted tones.
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Guitars: Fernandes ST 40, FST 125, Fernandes TEJ LTD ED and a Vortex. Chapman ML3 Pro Modern.

ADA MP1, ENGL E530, ENGL 840/50 Power amp, Carvin X100B, 2X12 cab.

MarshallJMP

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Re: Chorus issues.
« Reply #63 on: Time Format »

Scope looks good to me, ideal for audio repairs.
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rnolan

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Re: Chorus issues.
« Reply #64 on: Time Format »

Hey Richie, the compressor can add some VERY loud transient peaks which tend to clip things. eg my clean MP-2 patch makes my studio monitors clip from time to time, particularly when I belt the guitar a bit. Your results are not surprising, 9.5 is a very high master vol, with high compression (ie anything more than say 1.5:1 or 2:1 I'd call HIGH compression) it will send very strong signals to the next stage (which I'd expect to clip).  Now not to say eg 15:1 compression isn't usable (for say some nice (gentle) finger picking), you have to adapt for it (gain wise) down stream. If you "belt" a chord with that setting, expect clipping (in the eq and/or chorus stage ?) and turn things down accordingly.
It really helps if you understand the signal flown through each device and what each bit does to it along the way (gain structure). The MP-2 manual has a great block/schematic of the flow through it, MJMP posted the flow through the MP-1 quite a while ago.. (would make a nice MP-2 manual look alike MP-1 diagram MJMP?? if you were up to drawing it??).

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Studio Rig: MP2/MB1 > Eurorack UB2442FX-Pro > TC M-One XL > Behringer Truths (with Truth Sub) / QUAD ESL 63s
Live Rig: MP2/MB1 > Alesis Quadverb > Alesis Midiverb 4 > Yamaha AM802 > B200s/Carvin TS100/DCM200L > ADA Split Stacks/Mesa P112s

Richie_B

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Re: Chorus issues.
« Reply #65 on: Time Format »

Hey Richard, 9.5 was the default master gain setting for that patch. I am just wondering now what this all means for the broken chorus effect. As I mentioned earlier, when it's turned down the signal is clear and still with no chorus effect. This is the same with no matter what patch I use where the chorus is enabled. Now I know what I am listening for, I can hear the issue on any patch where there's even slight chorus. What I would be interested in knowing is how the signal flow works, how this would effect the chorus. Is it a trimpot, a resistor or something else? It's all interesting but I can't wait until it's resolved and I can think about mods to make it even better. I've considered saving some bucks for a second one to use in the meantime but wow, the prices have gone a little ridiculous lately, and as we know on this side of the world, shipping is a real killer. Kind of strange really because I can buy some gear from a German music retailer for a flat rate postage fee of $72 aud or there abouts. Probably some kind of deal they have with there postal service.
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Guitars: Fernandes ST 40, FST 125, Fernandes TEJ LTD ED and a Vortex. Chapman ML3 Pro Modern.

ADA MP1, ENGL E530, ENGL 840/50 Power amp, Carvin X100B, 2X12 cab.

MarshallJMP

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Re: Chorus issues.
« Reply #66 on: Time Format »

Well for the chorus, the signal after the loop is split into 2 signals, one is going to the outputs and one to the chorus

Filter to compression (NE570 1st part) to BBD to filter to expander (NE570 2nd part) and is then is mixed with the original signal (U11)

BBD clock is generated by a CD4046 (U24 )used as a VCO and in turn this one gets a voltage from a CD4094 (U25) which acts as a R2R DAC.
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Richie_B

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Re: Chorus issues.
« Reply #67 on: Time Format »

Thanks MJMP, still scratching my head over this and wondering whats next. Is it possible that something has failed along that path to cause the problem and if so, how difficult would it be to replace parts? I really hope I am able to do this myself, that in itself would be very satisfying. I really appreciate the help and support I've gotten here. If only I could get a few more mp1s to experiment on.
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Guitars: Fernandes ST 40, FST 125, Fernandes TEJ LTD ED and a Vortex. Chapman ML3 Pro Modern.

ADA MP1, ENGL E530, ENGL 840/50 Power amp, Carvin X100B, 2X12 cab.

MarshallJMP

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Re: Chorus issues.
« Reply #68 on: Time Format »

I guess is something is wrong in the audio path. But you need a scope to figure out were it is.
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Richie_B

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Re: Chorus issues.
« Reply #69 on: Time Format »

The bidding on the scope is getting too high, so will still be looking for one.
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Guitars: Fernandes ST 40, FST 125, Fernandes TEJ LTD ED and a Vortex. Chapman ML3 Pro Modern.

ADA MP1, ENGL E530, ENGL 840/50 Power amp, Carvin X100B, 2X12 cab.

MarshallJMP

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Re: Chorus issues.
« Reply #70 on: Time Format »

Maybe you're better off with one of those usb scopes?

Once you have a scope we can do a skype session and I can help you out.
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Richie_B

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Re: Chorus issues.
« Reply #71 on: Time Format »

Will go the usb option
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Guitars: Fernandes ST 40, FST 125, Fernandes TEJ LTD ED and a Vortex. Chapman ML3 Pro Modern.

ADA MP1, ENGL E530, ENGL 840/50 Power amp, Carvin X100B, 2X12 cab.

MarshallJMP

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Re: Chorus issues.
« Reply #72 on: Time Format »

Ok let me know when you have it.
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rnolan

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Re: Chorus issues.
« Reply #73 on: Time Format »

Hey Richie_B, I saw this today http://www.banggood.com/Orignal-JYE-Tech-DS0150-15001K-DSO-SHELL-DIY-Digital-Oscilloscope-Kit-With-Housing-p-1093865.html?utm_source=google&utm_medium=cpc&utm_campaign=Celc-DIY-ad-TIK-DSO150&utm_content=gary&utm_design=27&gclid=CP-57OO2_9ECFU1wvAodOYELiw  :dunno:
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Studio Rig: MP2/MB1 > Eurorack UB2442FX-Pro > TC M-One XL > Behringer Truths (with Truth Sub) / QUAD ESL 63s
Live Rig: MP2/MB1 > Alesis Quadverb > Alesis Midiverb 4 > Yamaha AM802 > B200s/Carvin TS100/DCM200L > ADA Split Stacks/Mesa P112s

Richie_B

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Re: Chorus issues.
« Reply #74 on: Time Format »

I wonder how well it works. I'm also wondering what the minimum sample rate should be, most of these that I've seen are 48MSa/s. I would hate to get one of these then realise that it wont cut it.
« Last Edit: Time Format by Richie_B »
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Guitars: Fernandes ST 40, FST 125, Fernandes TEJ LTD ED and a Vortex. Chapman ML3 Pro Modern.

ADA MP1, ENGL E530, ENGL 840/50 Power amp, Carvin X100B, 2X12 cab.
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