mwl168

Thanks to joehpj and Jose. That’s helpful. I have additional questions. Both KT77 and true 6CA7 (often referred to as the “big bottle” or “ fat boy” 6CA7) are beam tetrode while EL34 is a pentode hence the different construction as explained above. Yet, only KT77 tubes are reported to cause problems when used in the Blue Hawaii (and maybe the DIY T2). Why? I have used a quad of big bottle EH 6CA7 on my Blue Hawaii without issue and they sound really good!

Not sure which forum is the most appropriate place to post this topic. since it's technical in nature I chose this DIY forum. My question is - which Stax amps can one safely use the KT77 in place of the EL34 output tubes and why. Judging by the KT77 spec as stated on the datasheet, it should be compatible to the EL34 in terms of plate voltage and dissipation, etc.. But it has been stated by many that the KT77 should not be used in the BHSE. Can someone explain the technical reasons behind it? Also, what about using the KT77 in the Grounded Grid, Megatron and the DIY T2 and why. For me, it's both a learning exercise as well as a practical question - I've used the true beam tetrode 6CA7 in my Grounded Grid and Blue Hawaii (DIY) to good effects and wonder how the KT77 may fair in these applications. Thanks in advance for sharing the knowledge and thoughts.

The owner clearly got his priorities straight!

I personally am not convinced that there are true correlations between the events as stated in the article. Just because I pumped gas in my car one day and the oil price went up the next day does not mean I drove up the demand of oil that caused the price hike.

But it got the blood on the bracelet!

I’ve had Elear for a couple of years. It’s a good headphone and I did like it initially but over time it was the can I have the least desire to listen to. I cannot describe sound impressions frequently range by frequently range or if it has bumps and dips at what frequency. But something is amiss with the Elear when I just want to listen to and enjoy the music. Everything is relative, again, Elear by itself is a good headphone. I just happen to have other options at my disposal. Agree with Todd that, IMO and going by distant memory, the Clear has better tonal balance than the Utopia. The Utopia is more resolving and transparent. I was kind of WTF when Clear was first announced - how much can it be different from the Clear? Now I know how ignorant I was. My reason for starting this thread is so that a great headphone does not otherwise fall through the cracks, kind of like Kevin’s current feedback dynamic amp ?

I am surprised there has not been much of a talk of the Focal Clear headphone here yet. I bought a pair from Justin a few months ago during a promotional sales. It’s an impromptu buy mostly prompted by Tyll’s review and the fact I had just built a SS Dynahi. Don’t ask me why! To cut to the chase (my personal opinion of course), this is my favorite dynamic headphone I have heard to date. I agree with just about everything Tyll said about it. It just sounds “right”. Probably best overall in terms of reproducing the tonal and timber of instruments. It reproduces a well recorded piano as convincingly as I have heard from headphones. I own a pair of Elear and have listened to the Utopia under a unfamiliar environment a few years ago. Other headphones do somethings better than the Clear does, but taken as a whole, the Clear is my favorite of the dynamic headphones I own by a clear margin (hehe). It’s an easy headphone to drive but the amp does make a difference. I mostly listened to it either through my balanced CFA or the SS Dynahi using its stock balanced cable. To paraphrase Tyll’s comment, in the insane HiFi market today, the Focal Clear is a bargain especially at the promotional price of $1000 USD. Now I have completely lost my marble!

The hum is present with the Carbon amp OFF?

As what was said more than once in Top Gear - "you cannot call yourself a petro-head unless you have owned an Alfa". I was bitten hard the first time I laid eyes on and sit in an Alfa Romeo Gulietta in the late 70's in a show room. Owned a GTV6 for an all-to-brief one year or so. I miss that car tremendously after all these years.

^ Is this phono amp balanced or single-ended?

Is that a custom chassis of your own crafting?

The previous PCB order has been officially declared missing. The Fab house was kind enough to provide a refund coupon for me to reorder the PCB which I did. I used a different, higher-cost shipping option this time. With better luck this time I should receive the PCB in about 2 - 3 weeks.

Love the Harbeths and love the stools they sit on.

We have another hitch and delay. I ordered the updated GRLV boards in September and they were sent out to me around Sep 18. The tracking info shows that the package cleared US customs on Sep. 30 and was en route to me via US post network. I have not received it yet and local post office confirmed that they do not have it either. I got in contact with the manufacture and they asked me to wait for a few more days before they can open an investigation. I am going to give it another week and if the package is till absent the manufacture will provide a coupon at that time for me to reorder the boards. Apologize for the further delay. Will provide another update in a week or so. Table updated.

Not too late. I will add you to the GB.

Quantity of 1 for the mini T2 represents a pair of left and right channel boards.

Need a bigger TV.

At the risk of stating the obvious regarding measurements; there is a key factor of “correlation”. I remember more than 20 years ago I read an article to the effect of the three legs of measurements- “What do you measure? How you measure it? How do you interpret the measurements?”. As an example, it’s obvious that measurements of an amp’s physical dimensions have no direct correlation to how it sounds. I always wonder, much like many research in medicine, if some day someone(s) will eventually figure out a comprehensive set of measurements that truly have a direct correlation to how a device sounds to human ears (if that’s even possible).

Happy Birthday John!

1. I use the digital volume on my DAC but you can easily add a volume control to the amp. 2. This chassis I use is quite small - dimension is 160mm x 70mm x 311mm. It's only for the amp circuits and you cannot fit the entire amp in it. There is a PSU in a separate chassis. As an example, you should be able to fit the entire amp including the PSU in a chassis like this. 3. My rough estimate for parts alone would be about $700 US that also covers chassis, transformer, connectors, wires and a reasonable 4-gang volume pot. Like most things these days, labor is the biggest investment. Cost can escalate quickly if you start getting into fancy chassis, volume pot and boutique parts (resistors, capacitors, wires, etc.).

Depending on how small is small. You can consider Kevin's current feedback design which is the smallest desktop electrostatic amp I have built to date. All parts are current, simplistic power supply and very good sounding to my ears. Even though money saving isn't the main reason for me to go the DIY route, this current feedback amp is also the cheapest to build. The amp board (per channel) measured 184mm x 64mm. There is a thread in the DIY forum dedicated to this amp.

The good news here is that for the KG electrostatic amps that are often mentioned here (such as Blue Hawaii, KGSSHV, Carbon, Grounded Grid, etc.), there are proven PCB's for both the amps and the PSU's that many have built working and reliable amps with, myself included and I do not have a science degree and never forged a knife in my life! Extra safety precaution does need to be followed strictly given the high voltage involved! With that said, if you source correct parts from reliable vendors (Mouser, Digikey, etc., not eBay, not Taobao...), stuff the right parts in the right spots on the PCBs, exercise good soldering practice (many good tutorials on Youtube) and pay attention to layout of components (circuit boards, transformers, connectors, etc.) and wiring, your success rate is very high. On top of that, many knowledgeable people here will come to rescue should some things do go wrong provided that you have done your homework! It's lots of fun and a very rewarding experience!

It's never too late to pick up the soldering iron. If you invest the effort to learn, with diligence and good common sense those DIY amps you mentioned in your posts are really not that difficult to build.

Found this photo from quite a few years back. Canon 5D II with 135mm/F2 lens.