spritzer

It's one of my transformers and it is rated for 450VAC when loaded. It all measures just fine.

I would never run one of these with the cover on. The cover reaches 60+°C (so you can fry an egg on it) but the biggest problem is the PSU. The main power transformer will melt with enough hours on it.

It's their own layout but it is a S22.

Yup with a Sigma22 type PSU

Yeah and never discount the power of hype.

Yes but not to this set. I want a stock one for the collection (well stock-ish) but if I can find another cheap set then I'm all for a CNC chassis. Probably plywood like the HE90 if my new CNC likes it.

So I just got a recent ESP950 and I naturally could not resist taking a peek inside. Looks like they have finally updated the design of the amp a bit. New pot, new PSU board but the amplifier board is still dated 1990... There are also some clear signs of penny pinching going on. No name caps, non branded 3296 trimpots and that shitty as all hell volume pot. Bias is 600V off the main B+ line and through a 10M resistor. Next to is an "infinite" resistor which can clearly be replaced to trim the bias if they start to squeal. Not happy about the cap on the bias output but this is 1990 tech. The PSU is labeled 1317 so 2013 vintage so they are clearly still building them. It's quite funny that they didn't go to SMD for this as this is clearly a new layout. Gotta love Koss, hell they've made the same headphones for almost 50 years so why modernize. I left the amp alone except that dual section pot had to go. It can't track in stereo The headphones still look the same and were quickly modified to a SR-Gamma Pro cable. There is so much potential in those drivers but lost in the shitty as all hell housing. The earpads off ebay do help quite a bit but they should be angled to improve the soundstage.

I think the ratio is pretty much spot on... Given the number of headphones...yeah that is a lot of amps...

It can easily drive two sets at the same time but I agree, two output sockets are just a waste of everything.

Yup, those. They are well worth the low cost.

Happy Birthday my friend!!

One thing I've learned from 15 years on HF, it's very easy to sell something to the masses based on hype alone. Seen it too many times to count. Then the stuff just disappears from view... As for the ESP950, they really need to be modified to work best. The stock cable is gone and replaced with a Stax one (as the stock one is too short and I have a lot of Stax ones) and the damping in the back needs to be looked at. I'm also testing some ESP950 earpads off ebay. They are certainly a step up from the stock ones which are crappy as all hell.

The Liquid Carbon is finally here after some lovely USPS fuckups and well... it didn't disappoint. From the first notes I just wondered how could anybody think this even passable? It has that Cavalli sound, diffused, veiled, flat, boring, syrupy and with no extension at all. I mean seriously, this sounds good to people? There is no control over the drivers, it's all lost in a haze of distortion. As a fun comparison, I setup the ESP950 I got in the same shipment. The Carbon plus HD650 is what, 50% more expensive than the ESP950 but even with the POS E.90 amp the Koss walks all over it. We all know how good the HD650 can be so yeah... not brilliant.

Shoot me an email and I can give you the PDF.

I'd suggest trying them on a Cmoy to see if a superior amplifier might help.

Once one end has been inserted into the nostrils as instructed then it is bound to help. It is vital to achieve ultimate performance that all circuit breakers and fuses are bypassed. As we all know from the cable master Ray Samuels, nothing can strangle the flow of the larger electric molecules.

Now you just need a SR-X Mk3 Pro....

The Cree is well insulated at the hole so there should be no problems with using a steel screw. I would flip it over and look for any bad solder joints. That amount of difference with nothing blowing up could point to a bad connection.

Not sure where to post this but it might just as well be here, an update on the ongoing restoration of my SRA-7S. This is more a of complete rebuild/redesign but I digress. I bought the amp some 3 years ago for way too much and well...it was filthy and full of parts which were way past their use by date. Also the transformer was 100V only so the only solution would be to remove everything and start from scratch. Now I don't recommend doing this...like at all!! The amp is about the same size as the SRM-323 but with way more crap crammed in there. There are also some design issues which needed to fixed plus I needed to decide what to do with this thing. Since vinyl is dead to me, the phono stage was of no use so I left it out. That gave me enough space to fit a regulated PSU and a larger transformer. Just barely though. First up was the main amplifier PCB, I stripped of everything but the tube sockets and in went new parts: It was littered in carbon comp resistors and paper caps so they all had to go. Funny though that the values for each component are written in pencil on the back of the PCB. Now for the chassis and I decided that new RCA's were the only way to go plus is needed all new pots and switches. Stock values except for the filter section. It was single ended in the stock design but here I used all four channels so the values were halved. I'm replicating all of the features so the full 6 inputs are wired and even the mono switch. Way too much work but there is also no rush. Now the front panel was a problem. When it came here it was pretty disgusting. Some 50+ years of dirt and grime so when I tried to clean it, all the labels washed off. What you see here is in effect a reproduction of the orignal markings on the stock panel. This time done by laser so it will last forever. I went with the shorter switches for the power and mono/stereo for a sleaker look. The knobs are all brand new but they are identical to the stock ones. Sato still make them...

Mine doesn't feature the cascode. That was done on purpose.

I'm very happy with that sponge and an even crust all the way around. Nice lift too with no signs of it leaking down then proving.

This shows just why some of these amps sound like shit. A combination of low current, low voltage and bad current sources will change how they sound quite dramatically.

To get back to some actual R&D here, I've been doing some testing and I think the HE90 500V is highly optimistic. The drivers simply don't have the headroom built in that the Stax designs have and Senn were inserting plastic washers to try and stabilize the drivers. Well also to try and make the stators not crack but that's a different matter... Going down to the ~430V range might be beneficial to their performance but this warrants more investigation. It is quite retarded to argue with the designer of something and claim you know better based on no technical knowledge at all. Just based on how one "feels" about it. Better call that massively retarded. There has never been any doubt that the BHSE rolls off, it has been known since 2003 which is why the new grounded grid exists. That is the Carbon take on the same circuit, cleaned up to not have those issues. Doesn't mean the BHSE isn't a great amp but time moves on and we thankfully improve things and aren't stuck in a rut. I also suspect that we will see some major improvements as the new headphone R&D comes underway. Quite a bit actually...

Good point and something to look out for. I'd prefer a dual output unit for this reason but one can never be sure if it's not just two singles inside the potted chassis.

We all know the FRF graphs are utterly useless, they are just fodder for noobs who don't realize that test tones and the equipment used to analyze them just can't cut it. That's not saying the ear is a measuring tool, it's pretty much the worst piece of shit instrument it is, especially when coupled to our highly suggestive brains but it can do one thing easily...multi band analysis. I also don't see how this has anything to do with amplifier measurement though, these are totally different worlds as with the amps we can measure exactly what we need to know. I do think that the headphones can be properly measured too but the FRF graph is just the same as the age old THD spec. Utterly meaningless. Sure, the amp sounds different when changing tubes, nobody has said otherwise and how could anybody doubt that? You are changing an active component of the circuit so it will naturally change. My preposition was, has anybody swapped out tubes with identical specs? Actually put them on a curve tracer and map two identical quads. Then compare them in a blind test plus thorough full spectrum analysis of the amp. Then report back... A quad of EL34's is not the same as another quad of EL34's. I've done this with 6S4A's and all those "facts" about how they sound...well it is all bullshit. It helps to have hundreds of quads all matched within 1%. As for those two hapless souls, I don't despise them. I couldn't care enough to not like them but they are just epidemic of the HF issue. They know nothing about what they are talking about but the constant verbal diarrhea means people think they do. Think krmathis and HPA back in the day. Post enough and people thing you might have a single clue as to what you are talking about. Some idiot in the Shure KSE-1500 thread said it the best, you have to listen to me as I have more expensive gear than you.