CNC Phono pre-amp, Opamp rollng and Bugle comparo-->

Afternoon, gents.

Today Bill and I took my CNC and tried out some op-amps and compared to his Hagerman Bugle. The CNC has been running about a week so it should be stable with some decent burn-in.

CNC Phono pre-amp: Two dual channel op-amps with passive RIAA equalization. Two 9VDC batteries for power supply

Hagerman Bugle pre-amp: Three dual channel op-amps with passive RIAA equalization. Hagerman +/-18VDC power supply housed in separate enclosure with umbilical.
Chip compliment: Input-> LME49990 SMD's on adapter-> two Burr Brown OPA2134A's

Used a MM cart- Ortofon OM body with Digi 200 nude elliptical stylus.
Highly modified ST70 tube amp with low gain VTA board. Passive, ladder attenuator Pre-amp.

We started rolling chips to find a "best " combo.

Pair LME49720: This was a good all around combo. Tight bass, very good detail, musical, wide soundstage and very good imaging. The CNC circuit is from the datasheet of this op-amp.

LME49720-->LME49990 (two SMD chips on an adapter): Do you like detail? Well this has it. Bass depth is just a bit less than previous but bass attack is crisp. Not quite as musical as previous combo. *Contender*

LME49990--> LME49720 position two: A step up from previous pair. Bass attack crisper, more details all the way around, vocals bit more forward. Soundstage a bit wider. Imaging just a tad more refined. You can get lost in fretwork, cymbal decay, percussion details, vocalist breathing techniques. This is you detail KING.*Contender*

LME49990--> Burr Brown OPA2134A: This is another step up the ladder- bass is deeper, soundstage once again moved a little wider and very good depth. Details just a hair behind previous combo. Vocals and guitars bit more "musical" than previous combo. Imaging unchanged. *Contender*

Burr Brown OPA2604A- pair: Newcomers to the lab. Nice price. Bass depth was lacking. Soundstage just a bit smaller. Nice mids/vocals. Competent but no "Wow!" Factor. These were tested new, no time on them.

OPA2134A-->OPA2604A: Bass is back. Close to LME49990-->OPA2134. Just a hint of a sharp edge on the highs.

OPA2604A-->OPA2134A: Similar to previous combo but now definite hard edge to highs. Vocals pushed forward a bit.

OPA2604A-->LME49990: Nice all around- again, shy of great. Detail is a shade less than previous. Slight increase in bass. Mids and vocals just a bit nicer than previous.

LM49990-->OPA637 pair on SMD adapter: Two sets of single channel, SMD chips on adapters for best physical channel separation. Result? Meh. Bass is soft, soundstage just collapsed, all dynamics are weak. Like the power was dropped by 1/3 across the board. No-Go on this combo.

How about we swap positions?

OPA637-->LME49990: Wow! What a turn-around. Sounds like the old CNC is back. All dynamics are strong, good bass attack, soundstage opened back up (about middle of the pack), imaging better and details clearer. All that said, this is a good, but again, not great duo. Just a big change from previous combo.

OPA2134A-->OPA2134A: This is it.
It is right in so many ways. All instruments and vocals are most musical with this pair. Soundstage is wide, deep and tall. Imaging matches any other combo. Excellent bass attack and best bass depth. Guitar decay is just sweet with these. You give up just a little detail to the LME49990/LME49720 combo but you gain MUSIC. *WINNER*


Your mileage may vary. Pics to come and the Bugle showdown report.

Report continued...



If you can tear your eyes away from the beautiful, ultimate Empire turntable, the phono pre's are the two boxes on the left. CNC in silver, Bugle in copper capped with delicious hand rubbed Walnut.

No big expository rant this time.

The CNC, once we had optimized it with the op-amps available, is within spittin' range of the Bugle. The Bugle has also gone through the same iterations to arrive at it's current configuration.

Bass attack: dead heat- slight "flavor" difference.
Bass depth: Bugle by a nose.
Vocals: Bugle by a very thin hair. You know the color I mean...
Highs: Dead heat.
Soundstage: Bugle again by a nose. Just a bit wider. We found that width in the Bugle when we put the LME49990 in position one followed by a pair of OPA2134A's.
Imaging: Tough call, personally I think it is another hairs breadth difference in favor of the CNC.
Detail: CNC by a nose. Just a bit better all the way around.
Musicality: That hard to define quality which brings our recordings to life. Bugle by a nose.

Conclusion:
A CNC can be put together for about $30 not including batteries and enclosure. A Hagerman Bugle 1/2 kit gets you the PC board, BOM and instructions for $39. Add on the Digikey parts bill and you head north of $60 before batteries and enclosure. I do give Jim Hagerman big kudo's for his 3 op-amp design. It keeps the integrity of the music intact. And you can buy a very good DC power supply for the Bugle as well if you do not want to deal with batteries (and it would work great for the CNC!)
With all that being said, on a music quality vs. cost basis I cannot recommend the CNC highly enough. It does a heck of a lot with such a simple, easy to build circuit.

Thanks go out to Hypnotoad, BigBill and all the folks that jumped into the original thread and made a little experiment in low cost fidelity a big success.

Jim Langley

Great review Jim, the Bugle is a good design and liked by many so to have the CNC come so close shows that it's simple design doesn't get in the way of the music.

You need to try some AD823's in both the Bugle and CNC, you might be surprised how good they are.

Thanks for the in depth report and comparison.

Nice job!

HypnoToad said:

Great review Jim, the Bugle is a good design and liked by many so to have the CNC come so close shows that it's simple design doesn't get in the way of the music.

You need to try some AD823's in both the Bugle and CNC, you might be surprised how good they are.

Click to expand...

They are on the way, Phillip! :thmbsp:

JBL GUY said:

Thanks for the in depth report and comparison.

Nice job!

Click to expand...

Thanks, JBLG! I can never leave well enough alone. If you don't try and improve things, they just stay the same... :yes:

Nice review Jim, thanks for posting.

Thanks Jim & Bill - really enjoyed your review/report.

I've got two LME49720s and will try that with a stock CNC. Then I will swap in the pot to see what a tad of gain control will do.

I AM having fun!!!

Thanks to all - - -

.

Fine job!

Fantastic job Jim, your report is spot on! :tresbon:

G'day all, nice reports. I'm glad you like the OPA2134's. I've standardised on using them a long while ago.

I think they're hard to beat for general excellence. :yes: Regards, Felix aka catman.

catman said:

G'day all, nice reports. I'm glad you like the OPA2134's. I've standardised on using them a long while ago.

I think they're hard to beat for general excellence. :yes: Regards, Felix aka catman.

Click to expand...

+1 here Felix! They're my favorite OP amp and sort of the "gold standard" by which I now judge all others. :yes:

Just wondering..... With that sublime dual tonearm Empire and two phono preamps, were you able to audition both preamps at the same time? Lets see - an amp or receiver with two AUX inputs and just switch back & forth. Cool.

Also wondering how an LME49990/OPA2134A would compare to a OPA2134A/LME49990 combo. Your report seems to say that this pair supports each other, but will it make much difference which is the first stage? You have concluded that a OPA2134A/OPA2134A was better than an LME49990/OPA2134A, so it may be a moot question.

.

ghazzer said:

Just wondering..... With that sublime dual tonearm Empire and two phono preamps, were you able to audition both preamps at the same time? Lets see - an amp or receiver with two AUX inputs and just switch back & forth. Cool.

Also wondering how an LME49990/OPA2134A would compare to a OPA2134A/LME49990 combo. Your report seems to say that this pair supports each other, but will it make much difference which is the first stage? You have concluded that a OPA2134A/OPA2134A was better than an LME49990/OPA2134A, so it may be a moot question.

.

Click to expand...

We tested them back to back by switching interconnects. Both combo's of the 49990 and 2134A were tested. These had a detail improvement over the pair of 2134A's but just a little less "musical" to our ears. This difference is firmly in the realm of personal taste.

Fasterdamnit said:

This difference is firmly in the realm of personal taste.

Click to expand...

And this is exactly why you suggested that I should roll a few opamps. Different amps, speakers and environments will impart their own flavor, so everyone has to find something they like.

Vive la Difference

.

Would you be so kind as to provide a Digikey # for the 2134A? I wouldn't mind have a few extras on hand and to try some rolling when the time comes. Digikey leaves me baffled and beaten-down when I try to do a search.

I think one of the points of excellence with the Bugle is the isolated power distribution to the 3 ICs.
FWIW, The e-bay Bugle knock-off comes loaded with 3 Burr-Brown OPA2134PA chips in the good sockets. This one may get set up as a battery stand-alone RIAA mag stage 'standard'.

Thanks for taking the time to type all that, it's always interesting to read about.

FWIW, I don't often see Linear Technology op-amps mentioned in these threads, and some of the best results I've gotten with headphone amps have been with the LT1364, and some others. IME they tend to be very neutral-sounding, with better resolution than some of the BB op-amps.

dodog said:

Would you be so kind as to provide a Digikey # for the 2134A? I wouldn't mind have a few extras on hand and to try some rolling when the time comes. Digikey leaves me baffled and beaten-down when I try to do a search.

Click to expand...

Here you go-

OPA2134PA-ND

Pio1980 said:

I think one of the points of excellence with the Bugle is the isolated power distribution to the 3 ICs.
FWIW, The e-bay Bugle knock-off comes loaded with 3 Burr-Brown OPA2134AP chips in the good sockets. This one may get set up as a battery stand-alone RIAA mag stage 'standard'.

Click to expand...

My only concern is whether the chips are real BB's or possibly counterfeit. I agree it would be a great deal run off batteries.

Mr. Lin said:

Thanks for taking the time to type all that, it's always interesting to read about.

FWIW, I don't often see Linear Technology op-amps mentioned in these threads, and some of the best results I've gotten with headphone amps have been with the LT1364, and some others. IME they tend to be very neutral-sounding, with better resolution than some of the BB op-amps.

Click to expand...

You are quite welcome, Mr. Lin! I do want to test some LT's. I also like the idea of the simple headphone amps using a single op-amp. I will see about adding a pair of LT1364's the next time I have a an order. :thmbsp:

Fasterdamnit said:

You are quite welcome, Mr. Lin! I do want to test some LT's. I also like the idea of the simple headphone amps using a single op-amp. I will see about adding a pair of LT1364's the next time I have a an order. :thmbsp:

Click to expand...

I just took these two pictures for my thread in the headphone forum. This is one of the best op-amps I've tried yet, the LT1028. As you can see, I have two SOIC 8 single-channel versions of it mounted on a Brown Dog adapter, since the amp in question uses just one dual-channel op-amp normally (one op-amp goes on top, and one underneath). I know some of you guys have already been playing around with the Brown Dog adapters.

Anyway, if you can get your hands on some version of the 1028 (I don't think I paid much for mine), I highly recommend it. For the past couple weeks I've been using the AD826 - a good op-amp - but today I installed the 1028 and there was a very noticeable increase in detail and "air." You probably know what I'm saying. If you read the manufacturer's description of the 1028, they emphasize the extremely low noise of this design.






I applaud you guys for getting so into this. The differences between op-amps are often subtle once you're using only the best ones, IME, but these differences are hardly insignificant.


...

Great job guys!
I think the analog audio world needs more of these non-scientific head to head comparisons. It was a result of just such a test that helped us find the AD823 for dual and AD797 for single channel op amps. Well done!