Earspeakers

Good ideas, I'll check the belt. I read somewheres that there might be POTS on the board to twiddle for adjusting the tracking, I'll be on the lookout.

I have a Quattro I and II with different issues, appreciate anybody who has repaired CDP's. I haven't opened these up yet, doing some research first. Quattro I. Has tracking issue. Has trouble tracking some disks randomly (some 20% of the time) Quattro II. Sticking/opening drawer issue. Possible to replace the drawer mechanism? Any replacement drawer pointers? Thanks much -

$147 is market rate, actually slightly higher. I bought matched quads for $580 USD (actually might have been $560). My source still has them (and many more) available if anybody is interested, matched quad Brimar xf2 for immediate shipment. So not sure what the GB gets us here, no matching, slightly higher price, and no price break. Can you negotiate on a better price because of the quantity? If the price was down t $110 or something due to a GB then it gets interesting.

How many caps needed per amp, four?

Beautiful work. Personally I'm happier to have circuit boards though, PTP is challenging, and limits your circuits to what can be sanely constructed PTP. But if you want to do it Frank has the right idea. Plan on iterating and debugging your circuit, do it first in a test bench then do a final transfer to the finished amp, if you want a polished look. Here's a version of the terminals I use which give you convenient ground lugs http://www.mouser.com/ProductDetail/Keystone-Electronics/827/?qs=sGAEpiMZZMvz8LftK4jertCfhuxrwt2WUEp7yhBoVA8%3d But Frank, those you have are neat, where did you get them?

Here's a good link I found on the design of these. Here is the basic circuit: High Voltage ------/\/\/\/\/\---------+-------------> + to DMM/VOM R1 | | \ \ R2 / R3 / \ \ / / | | Ground Clip -------------------------+-------------> - to DMM/VOM

82k between positive and negative terminals, nothing between the tip and the ground clip or other two terminals. Probably a simple explanation but I'm missing it.

Seems more than likely that the probe is off, though by appearance it looks like a precision resistor. The probe looks like simply a resistor with HV standoff, is it a simple resistance or a reactive impedance? I did try measuring its resistance and didn't see anything useful.

Good catch! I mistakenly used the AC input impedance spec. I'll check again tomorrow with the Keithley and check the range I'm using, but given my equipment and this spec the Keithley looks like the best measurement, with the variation probably attributable to errors in the HV probe and handheld meter. Shows the importance of a good measurement or you might have a bias significantly off.

looks like one of those Caddock type resistors - an etch on a ceramic substrate or some such

A generic Chinese meter reads 577 VDC LV probe 631 VDC HV probe Keithley 2015 audio bench top DMM 590 VDC LV probe 645 VDC HV probe I haven't run a calibration on the Keithley. I could take it into work to get cal'd but probably not necessary, I think the measurement can be trusted, and it does correlate with the cheap Chinese. Taking the Keithley data the difference is 55VDC which is 9% of the LV value, but Kevin meant +- 10% of the HV probe resistance. According to the data sheet for mine the spec is +-10%, interestingly the data sheet for the 40kV version has a spec at +- 1%. Further, the data sheet for the HV probe specifies it needs to be used with a meter with a 10 Mohm, but the input impedance of the Keithley is 1MOhm. Not sure about the Chinese meter. Have to think about this

Good to know thanks, I had heard third hand to always use the HV probe. But for example, for some setting the HV probe shows 680 (or something like that) while the regular shows 580, whereas if low impedance they should be the same?

Let it burn in and check bias over several days, and try swapping tubes. Also use a HV probe to test the bias, not a straight DMM which will be about 100VDC too high. I had something like that too from these issues. One of my tubes died (early failure) so I swapped a new one and did a thorough checkup, now its ready to play after a minute and is dead silent.

2 amps (4 each) One dual and two single Thanks!

I have a quote for 4 sets of PS and Amp boards, I need one, three (only) more participants and I'll do the run. Blue board 92 mil board thickness (thick but not too thick) 2 oz trace I got them to come down a bit on the cost, it's now $314/set + tax and shipping. On this one I'll eat some of the cost and joiners can get them for $300 + shipping to them. I've got quotes from other sources and they're coming in more expensive, such as $280/board. Edit: This rev of the board (known to work) Here's the AMP board http://instantdfm.bayareacircuits.com/dfmquote/txm5x3d9/results/ PM me if interested. I also have an unusual/rare board I can't use, it's for standard off the shelf 400mm heat sink, is .125 thick with gold mask, if anybody is interested ($240 shipped) Taken

PCB Test point Jacks: I got this one from http://www.mouser.com/Search/ProductDetail.aspx?R=11011-Rvirtualkey53400000virtualkey534-11011-R Teflon post with copper center, I thought this must be for a bag (none of the documentation was clear). Nope, it's for a single jack! Mind you the jacks are beautiful, the perfect test point jack and easy too use but obviously too expensive. Any other sources? I've trolled Mouser but haven't found anything similar.

No I guess not. Sorry for being a new person in an old forum, I tried.

Take it easy mypasswordis - you like the recording, we get that.

And after a half hour it's 1-2VDC on both balance and offset on both channels, looks good! Surprised it takes some settling in, but looking good at the moment which makes me happy. I don't know how I got the 10VDC earlier. I've got a cheap DVM at the moment (sold my expensive HP jobs years ago when I thought I was done with DIY, ha ha), maybe it just flaked out. Anyhow first KGST seems to be good, thanks so much to all you wonderful people for your help! I'm now working on the KGSSHV, and a second KGST for backup duty (ended up with an extra transformer by accident)

Sarcasm aside, who cares that it launched his career? It often happens that what a person is eventually known for is different from what they were famous for in their time. Rachmaninov was primarily known as a performer, not to mention Bach. And I'll stick to my guns here - his young Goldberg is a calisthenic exercise. We used it as an example in an interpretation study lesson, basically what not to do. The later one is so much better. Unfortunately, after listening to the later one, I can't help but imitate it myself. Especially the first movement. Yeah I hear you! The first thing we hear imprints on our brains. When I was playing professionally I never listened to recordings for this reason (common for musicians). Nowadays as an amateur I depend on recordings to get my musical high every day, as I can't play as much as I used to. Anyhow, back to OT, today after a five minute warmup I'm getting 1-2VDC Balance and 5-6VDC Offset in both channels. Don't know whether to be bothered by that or not. Seems like it should be better.

Did a quick test with ear speaker and servo connected after long warmup, got 10VDC & 6VDC balance, with some 3-4 VDC offset. I had calibrated without servo and headphone to 0/0 (or as close as I could get), after reasonably long warmup. Should I be concerned or am I just seeing some effect from the headphone/servo?

4A is needed? Good to know, I throw 3A in builds by default. Also are you testing the power supply by itself, unconnected to the amp boards?

They are cheap on eBay

Yeah, A State of Wonder specifically. It has the early version, then a very late version he did, plus commentary and other material, I highly recommend it. In the later version he uses the sitting chair, and the hammer tacks in that nasty old Steinway. It's clear he was trying to get something more like a Harpsichord to achieve the articulation that the music demands. You can see the power of a mature artist with this. His tempi are significantly slower, the music comes alive and breathes. The famous early version is just a calisthenic exercise, hardly worth listening to. lol, great story!

All of this is generalities. In manufacturing roughly there's a sliding scale, with Satellite being the most rigorous (can't fix it after launch). Next is critical infrastructure (e.g. nuclear power plants), defense and scientific instrumentation. Then is general infrastructure (cellular, power system, etc). From there it goes into consumer which is hit or miss depending on the application and industry. I don't know the tube manufacturing explicitly but I'd be surprised if it wasn't similar. Many lines being like that, but surely the JAN products for A&D were done under Military contract as they've always been. Trust me, those contracts are explicit as to the performance. On par though Spritz is probably right, especially with the 6SN family which was general purpose. Plus these tubes are all long past their expiration date.