[Jupiter]

I'm building a portable META42 (my second DIY amp) for my Etymotics ER-4S. Will the suggested parts at tangent's web site make a good amp for my etys or should I make some substitutions/upgrades?

I was planning on using the META42 in my portable setup when it's finished, so I don't mind spending $100-$200 on it.

Current parts list:
PacTec HML-9VB-ET enclosure, 2x9V (in series) batteries, AD8620, EL2001, Vishay RN60 resistors (tangent's default values), Alps Blue 50k, Kimber TCSS wiring, Cardas GRFA RCA input connectors, C1: probably some Solen caps, C2: Black Gates NX 1000uF 25V, C3: empty, C4: Wima 6.8uF 50V (maybe Solens instead), C5: empty, WBT solder

 

[aos]

I would parallel the output buffers (so 2 per channel) since Ety's have lower impedance. It doesn't cost much more.

 

[eric343]

Use Vishay RN55 resistors; the RN60s are much larger and don't fit properly (you need to do some creative lead bending).

There's really no need to use anything larger than an 1/8th watt resistor in the META42.

 

[puppyslugg]

What are you using for a hp jack? Do you really need C1?

 

[eric343]

I use a Neutrik locking jack (recently upgraded from a Neutrik non-locking jack because of intermittent connection problems with my Clou cables), which I would *not* reccommend unless you have a nibbling tool because you need to make a *VERY* large hole to install it (I'm talking 2.5cm here!).

C1 is protection against DC on the input. You don't need it if you know your source has NO DC offset, but if you use it with a bunch of sources, it's better to be safe. The reason? DC offset is multiplied by gain. So, if you have a 1 volt DC offset (not too common, but still definitely possible) on your CD player's line-out, and a headphone amp with a gain of 10, then the *minimum* voltage your headphones will recieve is 10 VOLTS. High-impedance headphones like the HD600s will tolerate two or three volts max, low impedance headphones like Grados will fry at a volt.

 

[puppyslugg]

Hi eric 343,

Actually, I was asking Jupiter. I didn't see a hp jack listed. The neutrik would be a good choice, if he plans on using 1/4" plug. He(?) made it sound like it was for a portable set-up. I assume he may be using a pcdp for a source. I think most have caps at the hp/line output, as well as home cdp. But you should double check the dc offset to make sure. When I build my meta, I planned on not using C1.

ps

 

[zbuddah]

Quote:

Originally posted by eric343 Use Vishay RN55 resistors; the RN60s are much larger and don't fit properly (you need to do some creative lead bending).

hey eric343
where can you buy those Vishay resistors?

 

[zzz]

mouser has them (search *blows* though. find one and then tweak the part number).

 

[eric343]

USE the mouser catalog! The one printed on dead trees!

Otherwise you'll *never* find anything...

 

[zzz]

I guess that would do the trick

. I have found a copy of E-96 and a Vishay-Dale document on deciphering part numbers for these resistors instead, and used these to find all I needed.

No, certainly not the easiest way.

 

[Jupiter]

Thanks for good advice, guys!

aos, I wouldn’t have thought of this myself. I’ll definitely do this.

eric343, you’re right! I actually got some RN60s and RN55s yesterday and even the RN55s look big. I could mount the RN60s vertically, but if they won’t make my amp sound better, why bother…

puppyslugg, actually, I haven’t decided on output jack(s) yet. I need a 3.5mm jack and maybe also a 1/4" jack. I’m still looking for a high quality 3.5mm jack, but eric343's suggestion for a 1/4" jack should be good.

I’ll be using the amp with a PCDP mostly, so I’ll think about not using C1. I guess I will have to try it with and without the C1 caps. morsel used 4.7 uF caps here, so I’ll try that. Maybe Solen PB caps.

zbuddah, you can find Vishay RN55 and RN60 here:
http://www.mouser.com/index.cfm?hand...10&pdffile=286
You could also do a search for 71-RN60D-F or 71RN55D-F at Mouser's web site.

If you want the complete Mouser catalog (or parts of it), you can download PDFs here:
http://www.mouser.com/index.cfm?hand..._showdownload&

By the way, did anyone build a META42 for their etys? And with what results?


Thanks again!

 

[puppyslugg]

"I’m still looking for a high quality 3.5mm jack"

Do they exist? When you find one, let me know!

 

[Jupiter]

puppyslugg, I'll let you know if I find any.

Actually, my sound card (SoundBlaster Live) has some decent ones. These are gold plated and have a pretty tight grip. I hope I can find something of similar or better quality.

I'm also looking for 3.5mm plugs and the best I've seen so far is the Canare F-12. Cost is $3-7 depending on where you get it.

 

[puppyslugg]

jupiter,

Perhaps SoundBlasterLive sells replacement jacks.

As most hp's comes with 1/4" adaptors, (Senns, Grado, etc.) the locking Neutrik would be a good option. Of course, that means one more contact to contend with.

I have and used Neutrik 3.5mm plugs, and they work well.

 

[Jupiter]

I was planning on using a 3.5mm jack so I could avoid the adapter. I'm not sure which will be better, an average 3.5mm jack or locking Neutrik jack + adapter.

Anyway, the jack isn't very urgent. I could install all the other parts before the jack.