[jark]

Hi all, again. This is my second post and this time I like to ask about how to improve/change the sound of my Firestone Cute Beyond amplifier. As some of you know from my previous post, I also have a Musical Fidelity X-Can V8 which I really love because it allows me to listen for hours and hours with my Denon AH-D2000 without a single pain or ringing in my ears. Also I've found it to be the most pleasant sound ever, smooth, warm but clear and detailed...I mean , you know what I'm talking about... it's just a magnificent sound!.
The thing is, for listening at work I have the Cute Beyond, but I really don't like it, I just can't finish a cd because of the pain! and I have to wait a long time to be able to put my Denon's back on my ears again!. I just don't know how to describe this sound, it is too forward?, too bright?, no separation?, it is simple fatiguing and annoying!. The good thing about the Cute Beyond is that it used exchangeable OP amps so I would like to know which ones I should use to get a sound as similar as it can to the X-Can V8? is it possible to match a "tube" sound with a OP amp? which one do you guys recommend? and finally where I can buy it?
...by the way my Cute Beyond came with:

Main OPAmp: OPA 2604
Servo OPAmp: TL072

cheers!

 

[tomb]

Try an OPA2132 or OPA2134. They're very cheap and very "tubey". I suspect the real tizziness comes from the Cute Beyond's output stage, but it's possible a different opamp will help.

Don't mess with the servo opamp - that's not in the audio signal path of the amp circuit anyway.

EDIT: Stay away from AD opamps - they tend to be on the "hot" side.

 

[jark]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif Try an OPA2132 or OPA2134. They're very cheap and very "tubey". I suspect the real tizziness comes from the Cute Beyond's output stage, but it's possible a different opamp will help. Don't mess with the servo opamp - that's not in the audio signal path of the amp circuit anyway. EDIT: Stay away from AD opamps - they tend to be on the "hot" side.

Thanks tomb!...

and where can I buy those ones? do you know a online shop that delivers to Australia??
Also, what do you mean by "hot"?, I'm asking because the AD797AN has very good reviews...

best regards

 

[tomb]

"Hot" means pain and ringing in the ears, as you put it.

The Texas Instruments Burr-Brown OPA opamps should be available anywhere that sells opamps. The OPA2132 and OPA2134 are among the most common - Mouser, DigiKey, Allied Electronics, Newark, Farnell (in Australia!), RS Products, etc., etc.

 

[hifihead]

To my ears, the AD opamps are not "hot" at all. I highly recommend the AD797 opamps. I bought them at Digikey.

 

[tomb]

Quote:

Originally Posted by hifihead /img/forum/go_quote.gif To my ears, the AD opamps are not "hot" at all. I highly recommend the AD797 opamps. I bought them at Digikey.

Yes, the AD797 is a very good opamp. However, like most Analog Devices opamps, it is aggressive enough to have specific bypassing requirements. Otherwise, it may tend toward oscillation and ruined sound, higher temperatures, or worse.

Not knowing the particular circuit elements in the Cute Beyond, I felt it safer to recommend a milder opamp such as the Burr-Brown series. Chances are, the Cute Beyond doesn't include the circuit elements needed for the AD797 anyway - they'd have to be specific to that opamp.

On the other hand, the OPA2132/4 is the basic CMoy opamp and was chosen as such because of its "tubey" sound and mild action within a typical circuit. Note that the OP was requesting something a little more laid back anyway.

 

[sLite]

Quote:

Originally Posted by jark /img/forum/go_quote.gif Main OPAmp: OPA 2604

I had the same problem with my Firestone Fubar, same Opamp. Sounds like a complete mess with razorblade treble, crappy bass and yea well, it just sounds like a mess :>

Back then i searched a lot of threads and ended ordering dual opa627 and a browndog adapter. I'm pleased, suddenly there arent knives stabbing out of my headphones anymore.

Seems like firestone audio got hold of their problem, as they put the LM4562 in their recent version of the fubar. What a shame they still put the opa2604 in the cute beyond.

A friend of mine has the spitfire which has a LM4562 in it too, similar sound as the opa627, sounded better than my fubar, but the spitfire is a different piece of hardware, plus he had a supplier.
I would say you have a lot of options and you almost can't go wrong as long as you throw out the 2604.

As a side not: you don't need to replace the servo opamp, it has no direct impact on the signal.

 

[sLite]

Little thing to add, if i had the choice now, i wouldn't go for the dual opa627 anymore, they are much too expensive for the overall quality of the firestone products.
Doesn't mean they are crap, i still like the sound of the fubar a lot and will put it into my home rig as soon as the dacmagic replaces it at my work rig. Just think that you don't need a such expensive top end opamp for a entry level dac/amp.
(plus you need to solder them on an adapter which isn't that much fun)

I would just do some opamp searches here and order 4 or 5 budged opamps and give them a listen one by one.

 

[jark]

thank you all for your advice!...i think I'm going to give a try to the OPA627. I've found it on this site:

Op-Amps - Op-Amps - OpAmps - opa627 - AD797AN - LM4562

I would need also the OPA104 Adapter. It doesn't say anything about welding?

...don't care about the price...I spend 8+ hours everyday at the office so I need a good sound! and I ain't gonna buy another amp...

cheers!

 

[sLite]

Jep, you dont need to solder them like they look there. Didn't know that the 627 also exists in a version for putting them into a socket.

My construction looks like this: (one similar chip on the bottom side of the pcb)
http://img.skitch.com/20081002-1s1ji...2ap66p5d9s.jpg

They also have this type on stock at your site:
OPA2627, adapter + 2 opamps. looks like they sell it fully soldered together, ready for use. and it's actually cheaper than the 2 opamps + adapter.
But be sure to ask if that thing is really asembled or if it's just on the picture ^^

 

[randomasdf]

Have you tried toggling the gain switch? It seems to make a huge difference

 

[jark]

I used it at low gain...

 

[sLite]

Any experience report with the new opamp?

 

[thaddeussmith]

When did you get your CBeyond? I ordered mine and received on Monday ..it appears these newer ones come with a Burr Brown OPA2227 ..and so far, I have no complaints.

 

[pp312]

Newer ones? I bought a Cute Beyond about 3 years ago and it came with the OPA2227. And yes, it didn't sound "bad" to me.