mwhouston Posted August 9, 2018 Share Posted August 9, 2018 24 minutes ago, Rob181 said: Would be...if it was true... 24 minutes ago, Rob181 said: Would be...if it was true... So you have the same driver in the same box? With the stereophile warble tones in my system in my room there is no reduction in volume until 40hZ. At 40hZ the bass slot, the bottom of the speaker, goes off and the driver stops emitting. I'm on a wooden floor and the floor vibrates in sympathy to the tone. 40hZ! Link to comment Share on other sites More sharing options...
Guest Muon N' Posted August 9, 2018 Share Posted August 9, 2018 @mwhouston Was a shot, I had no luck finding those caps specifically with google-fu, so resorted to acronym finder. https://www.acronymfinder.com/VMP.html If they sound acceptable, that's what matters Link to comment Share on other sites More sharing options...
mwhouston Posted August 9, 2018 Share Posted August 9, 2018 I'm cool with them I just wondered if others could confirm what I found. The wiki post about caps is well worth a read. I'm pretty sure they are metalised paper. Which I is a good thing. Link to comment Share on other sites More sharing options...
danw1million Posted August 10, 2018 Share Posted August 10, 2018 630V Metallized Polypropylene. I hope this info helps. -Dan 1 Link to comment Share on other sites More sharing options...
mwhouston Posted August 10, 2018 Share Posted August 10, 2018 14 minutes ago, danw1million said: 630V Metallized Polypropylene. I hope this info helps. -Dan It makes sense but not according to wiki-caps. Happy either way. Link to comment Share on other sites More sharing options...
mwhouston Posted August 12, 2018 Share Posted August 12, 2018 After some conflab with others the caps are probably metalised polypropylene. Even better. A nearby friend in audio DIY crime did some testing for me on Lagoon. This is a 4S 12AU7 single stage tube preamp. The results are good. Distortion is quite low at 0.05% with the second harmonic predominant as expected. There was 50hz and 100hz hum there but low down and not audible in practice. Frequency response was from less then 30hz to over 20K which is all the test gear goes to. BUT this was into a crippling 15K resistive load. This leads me to question that these single stage preamps will only work into high impedance load, typically 250K!. There is an online impedance calculator in which you enter tube type, plate load resistor Rp and cathode resistor Rk and in bypassed or not. The calculator claims the output impedance should be about 13K! A lot lower than I have ever thought. To test this out we maxed the output of the preamp just prior to clipping (30V) then loaded it down until we got half the output voltage - about 13V. This occurred at a load of 15K!!! I maybe be wrong but this indicates the output impedance is 15K. Right or wrong. Very pleasing results all round and now I know this 4S preamp will drive SS power amps which have a input impedance of better than 15K (most will) and need less than a 13V swing - ALL WILL. Not only that the preamp sounds excellent. Link to comment Share on other sites More sharing options...
YNWaN Posted August 12, 2018 Share Posted August 12, 2018 (edited) I’ve done a number of DIY projects, DC blocker, mains distribution, room diffuser panels, large refurbishment and rebuild of my NS-1000Ms, speaker stands, phonostage, turntable power supply, record clamps and mats and also my turntable. My current project is a redesign of my current turntable and is the culmination of twenty + years of experimentation and development. Here is some of the CAD I have done - I would say actual construction is about 50% complete. Edited August 12, 2018 by YNWaN 4 Link to comment Share on other sites More sharing options...
YNWaN Posted August 12, 2018 Share Posted August 12, 2018 My current turntable: some rendering of the new deck: 2 Link to comment Share on other sites More sharing options...
acg Posted August 12, 2018 Share Posted August 12, 2018 @YNWaN, you should start a thread of your own. Tell us why you are doing what you are doing and the process you have gone through to make your decisions. The table looks great, but I for one would like to know more of the "why" and "how" if you have the time. 1 Link to comment Share on other sites More sharing options...
mwhouston Posted August 13, 2018 Share Posted August 13, 2018 It all stated with a free JAN GE 6J6A tube. Not sure too many know the tube. It has a B7 base which means 7 pins. There is one common cathode. Fortunately my tube amp designer buddy in Seattle whipped me up a preamp based on the tube. Because of the single cathode fixed bias is applied. I may just use some batteries which will never go flat from use. Here is the brd. Or more like here is the verobaord. 1uf poly input cap, metalised poly output cap, metal film resistors and ceramic socket. The only thing I had to buy were the sockets the rest I had on hand. Also I have a finished PS from another project. I need some more parts to complete the preamp but so far it's been a cheap ride. Link to comment Share on other sites More sharing options...
Batty Posted August 13, 2018 Share Posted August 13, 2018 Is that the same valve that is in the Headphone amp I bought from you? By the way it really suits the HE4xx phones I recently purchased. Link to comment Share on other sites More sharing options...
mwhouston Posted August 13, 2018 Share Posted August 13, 2018 2 minutes ago, Batty said: Is that the same valve that is in the Headphone amp I bought from you? By the way it really suits the HE4xx phones I recently purchased. Yes same tube. I only ended up with one and had to do something simple with it. Could be interesting. I have so many tubes and possibly better tubes,like real expensive limited edition 6SN7s tubes but just thought how many people do you know who have a 6J6A preamps? Link to comment Share on other sites More sharing options...
mwhouston Posted August 16, 2018 Share Posted August 16, 2018 I couldn't find a cheap suitable enclosure for this little 6J6A preamp. Most were too shallow and the tube would have been hidden in anything larger or deep enough. Then I thought "move the bottom of the socket to the parts side and then the tube will stand proud on the copper strips and be easily exposed". More than that I can now use a cheaper shallow enclsoure. A bit of fiddling around and a few new holes later here is the result. I have a PS ready to go and now for a couple of cheap enclosures. I have that worked out already. Link to comment Share on other sites More sharing options...
mwhouston Posted August 16, 2018 Share Posted August 16, 2018 (edited) The Markaudio speakers finally got some paint. Yet to paint the lower ports. Edited August 16, 2018 by mwhouston 1 Link to comment Share on other sites More sharing options...
A9X Posted August 16, 2018 Share Posted August 16, 2018 Finally snaffled a set of 18Sound XT1086 flares at an excellent price. So it's time to utilise the drivers I have gathering dust, especially as I've calculated I can use the same enclosure for them that my ATC build will use. So I can just get 2x the timber cut and I'll likely build both pairs at the same time. JBL 18" sealed 60-250Hz, 2 x JBL2118 (MHM), and an XT1086/ND1090 combo x-ing in at about 1500Hz. I have a bunch (8) sealed 12" units to hand off to below 60Hz. They'll be driven by a new audio only PC* and external soundcard and existing amps. * Should be finished over the w/e if I get some time. 4 Link to comment Share on other sites More sharing options...
mwhouston Posted August 19, 2018 Share Posted August 19, 2018 Just a mockup of a 6SN7-SE preamp I'm building. Chassis is yet to be painted. External PS. 3 Link to comment Share on other sites More sharing options...
McCvinyl Posted August 20, 2018 Share Posted August 20, 2018 Thats a very swish looking build just love your tube base to volume knob match up. Link to comment Share on other sites More sharing options...
mwhouston Posted August 20, 2018 Share Posted August 20, 2018 The big question is what colour to spray the chassis. Link to comment Share on other sites More sharing options...
mwhouston Posted August 20, 2018 Share Posted August 20, 2018 The knob is 4oz of solid brass but gold plated as are the tube bases which are also ceramic. Link to comment Share on other sites More sharing options...
mwhouston Posted August 23, 2018 Share Posted August 23, 2018 Bought some Altec 511B horns from a fellow SNA member. I sourced some compression drivers from a local DJ store nearby. The drivers are Itallian (link to follow) and expensive compared to some others. Looking for hifi sound from the horns. Here are some old Xovers I modded to work better with the horns. Xover at 1600hz 2nd order on the woofer and 3rd order on the horn. Looks rough but should be enough to have a listen. 2 Link to comment Share on other sites More sharing options...
mwhouston Posted August 23, 2018 Share Posted August 23, 2018 A link to the compression drivers. https://djcity.com.au/product/faital-pro-fa-hf108r-hf-compression-driver/ Link to comment Share on other sites More sharing options...
Happy Posted August 23, 2018 Share Posted August 23, 2018 2 minutes ago, mwhouston said: Bought some Altec 511B horns from a fellow SNA member. I sourced some compression drivers from a local DJ store nearby. The drivers are Itallian (link to follow) and expensive compared to some others. Looking for hifi sound from the horns. Here are some old Xovers I modded to work better with the horns. Xover at 1600hz 2nd order on the woofer and 3rd order on the horn. Looks rough but should be enough to have a listen. I have a pair of 811B for a hopeful project....watching what you’re doing. 1 Link to comment Share on other sites More sharing options...
nzlowie Posted August 23, 2018 Share Posted August 23, 2018 46 minutes ago, mwhouston said: A link to the compression drivers. https://djcity.com.au/product/faital-pro-fa-hf108r-hf-compression-driver/ These are what I've got now for the top end. They sound good to me..... 3 1 Link to comment Share on other sites More sharing options...
mwhouston Posted August 23, 2018 Share Posted August 23, 2018 13 minutes ago, nzlowie said: These are what I've got now for the top end. They sound good to me..... Which compression driver are you using in the top horn. Got a link? Link to comment Share on other sites More sharing options...
nzlowie Posted August 23, 2018 Share Posted August 23, 2018 Sorry, my reply must not have been clear. These are the Faital Pro HF108's. I've got them crossed really hi as I want the Yamaha's to do most of the work. Around 7khz xover, second order. 1 Link to comment Share on other sites More sharing options...
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