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tarandfeathers wrote:minor niggles

Hey ktone, that looks almost exactly like what I used to run into with my Roland UA-30 USB sound card (which was pretty badass back in 2000 or whenever it was I bought it). I was never able to remedy it, but I did notice that another UA-30, a different one that I bought from a friend, didn't have the same problem. I've got no idea what causes it, but the admittedly crappy workaround I came up with was to record with the signal level low enough that it didn't clip on that half of the waveform that was getting clipped.Stupid digital.

tarandfeathers wrote:Put a new battery in my new A810, went with a NiMH one and it seems to be running smoothly so far, holding it's data, not freaking out and rebooting in the middle of playback etc. Also cleaned all the old battery crust off the pcb and checked the continuity of all the tracks that had crusty stuff on them.Checked the azimuth and did a repro calibration for 15 & 30IPS, discovered that the bass repro adjustment doesn't do anything on one of the repro cards (swapped the card into the other channel and the problem moved with it). Looking at the schematic, probably a schmutzed DAC or maybe one output of the decoder is dead. Tried re-seating the chips to no avail, so I will pick up a new one of each tomorrow and see if I can finish doing the line up properly so I can get on with mixing some records!Put the new DAC in, works like a charm. A few minor niggles I want to work through and I need to build a stand and put some meters on this thing, but I'm really delighted with it.

Ampeg V-4.It wasn't working. I bought it that way. Turns out three resistors had fallen out and were floating in the chassis; two screen grid and one input grid. I replaced them. Amp works, but there is a loud hum. I pulled the phase inverter tube, and I'm still getting the hum. So, power section filtering? I guess I'll switch power tubes and see if it clears up.Has anyone reformed caps in these amps? If I'm going to replace the caps, any advice?Ben

benadrian wrote:Has anyone reformed caps in these amps? If I'm going to replace the caps, any advice?Hey Ben, I haven't done this, but Adam from Police Teeth did this to my V4 a few years ago. He posts here very occasionally as onoroff.

All three resistors were right above the 12AU7. I agree, the amp is pretty poorly assembled. It's a shame they sound so damn good. Those on board tube sockets are just miserable.Also, $95 bucks! Damn. I hope I can reform. If not I think I'll just have to suck it up and refurbish.madraso\_ wrote:Ben.its pretty simple. try fliptops. They are a bit pricey, but they should have a near exact can replacement for almost any ampeg, and many other hard to find ampeg oddballs as well.here is a link to their cap-kit page.[url]http://www.fliptops.net/catalog/index.p ... =2a&page=2[/url]it is retarded the way the tubes hang from the boards. The heat they generate seems to cause all sorts of shit, maybe that contributed to your resistors falling off? when I bought mine I put a fan in them to help minimize this kind of thing.

Ben.its pretty simple. try fliptops. They are a bit pricey, but they should have a near exact can replacement for almost any ampeg, and many other hard to find ampeg oddballs as well.here is a link to their cap-kit page.[url]http://www.fliptops.net/catalog/index.p ... =2a&page=2[/url]it is retarded the way the tubes hang from the boards. The heat they generate seems to cause all sorts of shit, maybe that contributed to your resistors falling off? when I bought mine I put a fan in them to help minimize this kind of thing.

madraso, that is one tidy build!I've just been finishing off a project, rebuilding a Linear Conchord 30 from scratch. I changed the preamp to a AC30 and took out the negative feedback.Towards the end of the build.. got a lot of crackling and a lot of hum. Replaced all the filter caps. Didn't make any difference. Plate voltages were high on all tubes, so altered the B+ resistors.Tried it with one power tube, amp worked, albeit with hum. Put tube in other socket and just got crackling. Changed cathode capacitor and noticed that I hadn't soldered the ground (shared with cathode resistor). worked fine, but with the extra demand on the power transformer, the B+ supply was very low for the PI and preamp.Changed those resistors, works fine now, albeit a little quiet for a 30 watt amp.Added some extra filtering, turned it on and 5AR4 went in an arcing mess. Oh well. At least the amp works now.I am not showing a picture of the insides. It looks a mess compared to madraso's.

Madraso...Could there have been an ultrasonic oscillation that sprung up when some negative feedback was removed? I have no idea what would happen if some crazy HF was cranked at maximum volume for a while.Ben

We've had some ongoing noise issues in the studio that we've been trying to work out. The anchoring components of our studio are: A Soundcraft 800C 16x8, RME Fireface 800 with 8 channels fed through ADAT optical from a Motu 828mkii for A/D and an ADC 96pt TT patchbay with punchdown and normals out. So, the initial problem was that through general incompetence or simple carelessness, we made a bunch of cables wrong when we had our 2 day long "solder party". Everything was getting to the mixer fine - we run a 24 channel snake with xlr connections into the mic preamps. However, the line outs on the mixer were wired wrong. The Soundcraft has unbalanced line outs, which we run to the patch bay and normalled to the inputs on the the A/D. We're using this 3-wire Belden cable with foil shield for all the hook-up (partially because the wires are perfect for the punch down bay). The line outs from the console were wired up with Tip - Red/Black and Sleeve - Shield, sort of like a normal TS connection. However, when this gets to the RME, we had problems. To reuse existing connectors, we kept the TRS on the inputs to the RME. Here, the connector was wired Tip - Red, Ring - Black, Sleeve - Shield. Oops. Since the RME shorts the Ring and Sleeve when running unbalanced, we were getting some major noise (nominally around -75dBFS). We have been using a workaround for some time, simply bypassing the patchbay and using a TS snake cable to hook the line outs directly to the RME, which was getting us a reasonable -88dBFS or so.However, I have a session coming up next weekend and want to use the patchbay, so I decided to finally fix this mess. The solution: TS connections on the line out with Tip-Red, Sleeve-Black and Shield - Lifted going to the patchbay - normalled to TRS connections on the RME with Tip - Red, Ring - Black, Sleeve - Shield. This resulted in a dramatic improvement in noise even over the TS snake cable, getting the nominal level down to about -99dBFS. That's not bad considering the unbalanced cable run and a dynamic range for the RME of about 109dB. Unfortunately, the Motu has considerably lower dynamic range, around 95dB, and the best I could do here was around -81dBFS. Tested to make sure everything is patching OK. I d still like to experiment with grounding schemes at the patchbay, but for now it seems OK.Tonight, we are going to wire in the outboard gear “ just 7 channels of outboard preamps, 4 channels of compression and a stereo EQ. Considering there s not all that much, I m hoping it will only take a couple hours. The master/monitor section, jerry-rigged as it may be, sounds fine, so we ll leave that alone for now.