mwl168

Single digit temperature outside. Time to power up this glorious sounding amp. What a treat...

I am in US and figured you are in UK thus the comment on the shipping cost.

I may have spare boards left but, given the shipping cost, it probably makes more sense for you to have them fabricated.

A much better idea is to see if you can obtain one of the pot PCB from a GB (or other sources) some time ago so you don't need to solder directly to the pins on the pot. No need for fancy solder IMO. I have solder from Cardas, WBT and good old Kester and don't believe either one makes an audible difference. Get a good quality solder and solder the joints well is key.

My car has over 400 hp and can go over 150 miles/hour. Even though I don't use all that power nor intend to drive it anywhere near that speed. I enjoy it just as much.

Check out Kevin's (Dr. Gilmore) current feedback electrostatic amp if you are looking for a compact and first DIY project. I suggest it because it's easy to build, low cost with very simplistic power supply requirement and, more importantly, a very nice sounding solid state amp that uses all current production parts.

The original design of Blue Hawaii uses 2SK170 BL grade which has the IDSS grade in the same range of LSK389B. Double check the data sheet to confirm. 2SK170/LSK389 are JFET so using either 10K or 50K volume pot should be fine. 10K pot may be more ideal if your source can drive it.

I had a pair of Apogee Duetta Signature which I foolishly sold. They are wonderful speakers and do things I have not experienced with other type of speakers. They were difficult to place properly and seem to be choosy of the room which was the main reason I sold it. It's the single piece of audiophile gear I miss the most all these years.

I have one possible theory to consider; Everything being equal, cable capacitance is in direct proportion to the length of the cable because of the amount of conductor material needed. Enough capacitance and high output impedance can form a low pass filter that, in extreme cases, can roll off the highs.

In my own own humble experience with tons of different interconnects, ranging from my own DIY Mogami/Neutrik cables costing less than $50 to those boutique cables costing over $1K, it's usually a combination of the following factors if an interconnect cable does make a difference: 1. the cable has quality/construction issues that induce capacitance, impedance or even connection issues 2. one or both of the equipments being connected have inadequate output/input impedance, drive capability, grounding, etc. 3. length of cable, Nate already touched on this 4. shielding of cable - especially in "noisy" environment Personally, I want my interconnects to be just that, an interconnects, and not injecting other artifacts. A properly constructed interconnect does just that and no reason for it to have a sticker price that resembles fine jewelry.

JimL explained the details of the cascode CCS in the thread below. It's a great read. In short, using the combination of 10M90S and DN2540 is intended by Jim. There is also a SRX Plus build thread in the DIY forum that also contain much information you'll find helpful.

The "SRX Plus" is what Jim (JimL) named the circuit he modified based on the SRX schematic which I believe Stax released to the public decades ago. The modification, among other things, adds CCS to some critical positions which significantly improves on the performance of the original circuit. I don't believe Stax ever produce an amp based on the SRX circuit. I built one and I love it!

Megatron?

this is what I woke up to this morning...

I think it’s a deleted scene from “Shining”.

I can confirm that the full-size SuSy Dynalo offset does drift even with servo engaged as Chris stated. My own observation: 1. The drift is mostly ambient temperature related. A cased amp drift less than a free-standing (aka air-chassis) amp does 2. The + out and - out drift the same amount so, while the offset relative to ground drifts, the voltage difference between + out and - out are fairly stable

Maybe he bought them on Amazon Prime Day.

I, too, have re-terminated my headphones with 4-pin XLR and built a 4-pin XLR to TRS adaptor cable. Additionally, I replace the female TRS socket with 4-pin XLR on single-ended amp when I can. To me, the primary benefit of a 4-pin XLR connector for single-ended amp is to avoid the brief shorting of output when plugging and unplugging headphones with TRS connectors.

Maybe that’s just the right-rear speaker of the surround-sound system.

My recommendation is to phase-in the changes. The safety resistors should be considered a must-do and replace all the capacitors as you have already did. I consider these 2 steps phase 1. I would then listen to the amp with the existing transistors for a while before moving to phase 2 - replacing transistors. I would take a few measurements of the working amp prior to changing the transistors and I may do it one channel at a time so you can reference between the two in case something does not work right. I would further break down transistors update into multiple sub-phases. This way, if something does not go as planned it’s easier to isolate the causes and trouble shoot. Also, preserve and keep the old transistors in case you need to put them back in. They are likely obsolete and unobtainable.

I think any good quality film capacitor, including the one in your link, should do fine.

Those 4.7uf are power supply bypass capacitors. The 4.7uf paralleled the 100uf electrolytic caps. I use some WIMA PP caps with appropriate voltage rating. And I used multiplayer ceramic caps for the .1uf.

Hi Chris: For my universal PSU (GRLV + GRHV), I use a Galaxy 3U chassis which comfortably accommodates the 680uf/550V capacitors. The chassis has no true finned heatsink, it has what the vendor calls the "quasi heatsink". I use this PSU to power my Carbon, Blue Hawaii, Grounded Grid and the CFA. I bolted the transistors of the GRHV to a L angle which is then bolted to the "quasi heatsink". Even powering the Blue Hawaii, which draws much more current than the Carbon does, the "quasi heatsink" only glows warm to the touch. I believe even if you just bolt the GRHV transistors to the bottom aluminum plate it should be fine - this is exactly what I did with my Megatron PSU which draws even higher current I believe.

None of the attachment seems to be working for me. Do others experience the same issue?

Happy Birthday!