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Vacuum Tube Audio Gear
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SimonP
DIY Champ
Feb 17, 2022
In Show and Tell
I completed my build a few weeks ago, took a break before verifying all the connections, and testing. Today I ran the Audio Analyzer suite on the build - things look OK. I need to dim my blue LED (I know some have issues with blue LEDs - but I like them, I still remember when I got my first one - so much better than the red/green/amber ones I got used to (I'm close to 60, so yes, that was about 30 years ago)). Just noticed I also need to reverse the screws/nuts on the choke. The Amp sounds sweet - I'm playing some Joan Armatrading on it right now. Will let it burn in over the next few days. My amp till now was the Adcom GFA-535 (a decent amp). This amp is no worse from what I've heard so far, I think it sounds better - but I still need more time to listen. (So while typing this up I moved on to 'Goombay Dance Band' and they are sounding much more open and imaged than I remember). I did have to go through 4 6SQ7's to get a pair that kept THD <1% - had seen THD at 1.8% on one of the tubes I had. Thanks to Skunkie Designs for sharing this project - was definitely worth the effort to build this.
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SimonP
DIY Champ
Nov 26, 2021
In Questions & Answers
Does anyone know of a good source for the Sylvania 6SQTgt tubes? With my EAR834 build done, think I'm ready for the EL34/6SQ7 build. I'd like to try and keep the tubes the same as in Skunkie's build (to start with). I'm going to try what tubedepot offers - however they say 'various brands'. I've also gone for the JJ EL34L and JJ 5AR4. I've managed to find everything across several vendors - listing here if anyone else is looking: Mouser.com (chokes, resistors, electrolytics, LED) tubedepot.com (tubes, Solen cap) parts-express.com (transformer, alps) edcor (transformers) soniccraft.com (mundorf caps) angela.com (Chassis, tube connectors, point-to-point tag strips) ebay (Speaker and Phono connectors) amazon (Volume knob) youdaelectronics (tube base rings) Edcor looks like the longest lead time - they say Feb/Mar 22 - so maybe a while before I get to finish this. Just FYI - inflation is starting to hit the parts list for this build too - I'm just over $700 for parts and shipping (using the 273BX). -Simon.
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SimonP
DIY Champ
Nov 24, 2021
In Show and Tell
Been working on this for a while, have got most of it done. I still need a bottom plate (for safety) and a bulkhead/shield between the PSU and main board (getting a tiny bit of hum when ear up against speaker....). I'll probably also tidy up some solder joints (taking pictures lets you see what can be improved....). I also need to shorten my standoffs for the main board so the tubes stand a little higher (so I can change them). Also need a knob for the pot (I'm using a relatively high output cartridge, so added the 50K pot so I can adjust output as needed). I did some changes based on a thread on the lencoheaven forum (https://www.lencoheaven.net/forum/index.php?topic=26658.0) I'm using JJ E83CC/12AX7 Frame Grid tubes - planning to try a SPAX7A for V1. I was using a Schiit Mani for my phono stage (which I liked). This sounds more open, and the bass is tighter. Hopefully it will get even better as it gets some use. (The turntable is a refurbished Rotel RP850) For those looking closely - the piggy backed (parallel) resistors on the PSU board in the 0.22R spots was my "fine tuning" to get 6.3V on the tube heaters. With 0.22R alone I was only getting 6.1V. Need to shorten the standoffs to get the tubes a bit higher. -Simon.
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SimonP
DIY Champ
Oct 26, 2021
In Introductions
Been watching all your videos - Thanks for a down to earth channel. I retired just over a year ago and have slowly got back to working on my Audio system. I recently restored a Rotel RP850 turntable (circa 1980), the added complication was it ran on 240V/50Hz. I'd always intended to recut the pulley to handle 60Hz, well - after 40 years that never happened. As Chinese inverters are now cheap, I ended up powering it that way. The experience of hearing some of my LP's again encouraged me to look into a better phono-stage. I'm in the process of building the EAR834 phono stage - I learned a lot from your videos - thanks! I'm also following some of the suggestions (TRLH mods) from the thread on lencoheaven (https://www.lencoheaven.net/forum/index.php?topic=26658.msg352026#msg352026). I've got everything built and am checking the voltages at the moment. (I used the Antek AS-05T280 toroid). I've got my 285V, but my heater voltage is at 6.0V (with tubes) - looking to decrease the 0.22R resistors a little to see if I can push it up to 6.3. (I'd initially thought this was within specs, but some googling seems to suggest you can reduce tube life by running the heaters at less than 6.3) Hopefully I can get the phono stage complete over the next week - I'll post pictures when I have it all done. Simon.
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