The best phono preamp under $1000 (aka the Hagerman Bugle upgrade thread)

[wyn palmer]

I’m not able to say which op amps will work best based on the specs. I’m just trying to help @cgallery with what I have tried & share my experience with what I tried out. I do know that it will make a difference.

Is it possible to tell which op amp will produce a better bass response? I’m curious why the 1612 does this when placed in the 3rd slot with the 2210 in the first two? It would be nice to see how or why it does that.

The opamps should not "improve" the bass response except under very particular circumstances which are not found in the Hagerman. It may be some other effect that is being interpreted as resulting in an improved bass. For example, increased HF harmonic distortion can create a sense of false brightness that can appear to suppress the bass.
Reducing the high order high frequency distortion can create the impression of improved bass.

 

[desertrat748]

The opamps should not "improve" the bass response except under very particular circumstances which are not found in the Hagerman. It may be some other effect that is being interpreted as resulting in an improved bass. For example, increased HF harmonic distortion can create a sense of false brightness that can appear to suppress the bass.
Reducing the high order high frequency distortion can create the impression of improved bass.

All I know is what I hear. It’s repeatable on different builds with a different set of the same op amps.

So much so that I have to adjust for it. Every time.

I definitely would be interested in what is happening with the output and testing. I don’t have any equipment nor knowledge of what to measure.

 

[mkane]

Doesn't matter what your rolling OPA in. You need to be able to check stability.

(1) Swapping Op-Amps... you have checked to see it's stable haven't you ? | diyAudio

 

[desertrat748]

For example, increased HF harmonic distortion can create a sense of false brightness that can appear to suppress the bass.
Reducing the high order high frequency distortion can create the impression of improved bass.

It might be just this. I know the results were dependent on the c4 - c6 changes. Most noticeable was the c5 to silver mica from Jim’s original c5.

 

[desertrat748]

It would be kinda nifty were someone to create a spreadsheet of all the project boxes with internal dimensions such that we could find compatible boxes

The bugle2 pcb is approx 2 3/4 “ wide and 4 3/4” long. I used a base of 3” x 5” to mount it and built around it. The build needs at least 20 mm of height clearance for the parts listed. I think 25 mm or 1 inch is better and 30 mm would be better if you used large caps.

I’m just getting the hang of welding so prefab is nice and easy. Someone who has good tig welding skills could easily make a custom housing from aluminum.

 

[oranda]

Interesting thread. I recently purchased a Bugle 2 on eBay for $99, it should arrive today.

My standard phono preamp is a TC-750 on which I've removed the cartridge loading caps. I've used a bunch of other phono stages (MoFi StudioPhono, Parks Budgie, Realistic 42-2109, etc.) but the differences among them tend to be pretty subtle.

I've read a lot of good about the Bugle so look forward to giving it a listen.

Yes, I used a TC-750 for a bit. I found it to be serviceable but veiled and lacking in dynamics. I think you will enjoy the Bugle and be very pleasantly surprised if you perform some of the upgrades.

The differences between phono preamps at a similar price point will be small as the components they use are often of similar quality. Opamps like the OPA1612 and OPA2210 will be better than the ones that come in most gear, as are the mentioned capacitors.

Please let us know how you like the stock Bugle and how it improves if you decide to mod it. Cheers!

 

[oranda]

Another Q: The enclosure for the Bugle, is that a standard model available somewhere like Digikey?

From Mouser (part no 635-A-27-B) as well as directly from the Serpac website.

 

[oranda]

Interesting.
Wish the boards weren't so small though.
My hands shake too much these days to work on them.

I've got both a bugle 2 and a 3 that started making horrific noise.
Nothing obviously wrong that I can see.
Modding them would be a fun project.

I wonder if JH would be willing to look at your Bugle 3. You might try writing him. Cheers!

 

[oranda]

It depends... The data sheet doesn't have much in the way of audio specific information- no distortion for example, and the input current noise would make it a poor choice for MM. Another option might be the LT1115 or the AD797, and the OPA1612 is close (yes, I see that it is disliked) but then the Hagerman will have issues due to the high impedances chosen in the feedback loops and they'll all be terrible for MM- just like the LT1028.

Well, you are right about the noise figures of the LT1028 (which are similar to the LT1115.) But the playback noise of even an UHQR pressing is going to bury the noise of these op-amps, so it's not something I would disqualify either device on. I have used the LT1028 and I thought it was an excellent opamp.

 

[oranda]

It's a fallacy that capacitors which "go to ground" are not in the signal path. They are. WP explains their function below. Capacitors which produce distortion in those locations will distort the signal.

Completely agree, and the negative effects are reasonably easy to hear as RIAA capacitors to ground are exchanged.

BTW, LOVE your "Moving coil step-up transformers explained" article. It's a fantastic resource for determining SUT internal losses and MC output voltages. Also like the discussion on limitations of resistive damping on transformer ringing. Overall an extremely informative article.

 

[oranda]

View attachment 2709202
^ Absolutely, 100% unequivocally Not! If you haven’t built it and tried it. I could not have predicted the results, repeated results from 2 different builds and 2 separate sets of both opa s.

Measurement are extremely useful, especially in identifying errors or changes we may not be properly pinning down just by listening. But I'm with you in that we need to take a hard look in the mirror if we are denigrating the validity of listening tests as a turntable/vinyl community. If measurements were all that mattered, instead of being here we'd be laughing at LP dynamic ranges while posting about our DAC builds in a digital forum. They have S/N ratios and zero wow and flutter. We have, "it just sounds better, man."

Measuring results on a meter may show differences with limits that I can’t hear. Measured results with my ears always show results that I can hear. Strange.

^ I'm stealing this at some point.

 

[wyn palmer]

Measurement are extremely useful, especially in identifying errors or changes we may not be properly pinning down just by listening. But I'm with you in that we need to take a hard look in the mirror if we are denigrating the validity of listening tests as a turntable/vinyl community. If measurements were all that mattered, instead of being here we'd be laughing at LP dynamic ranges while posting about our DAC builds in a digital forum. They have S/N ratios and zero wow and flutter. We have, "it just sounds better, man."



^ I'm stealing this at some point.

I disagree. The issue is that usually the wrong things are measured. Crude metrics like THD per se are of essentially zero value, but there are other metrics that are useful- ones that take into account the actual non-linear behavior of the auditory system, that recognize the effects of masking, for example, and the reaction of the system to high order distortion products that are audible down to the threshold of hearing, even in the presence of noise.

 

[wyn palmer]

One other thing, the WP design- which uses these metrics to guide the design choices- has been extensively tested in comparative listening sessions versus many different phono stages, including some extremely expensive ones, and has performed well, generally being preferred- at least by those who are not wedded to tube designs where the odds are 50-50 at best. It seems that having extremely tight RIAA compliance and distortion that is below the audibility threshold over the entire audio range together with very low noise does seem to provide a neutral presentation and extremely good retrieval of detail without false brightness.

 

[cgallery]

One other thing, the WP design- which uses these metrics to guide the design choices- has been extensively tested in comparative listening sessions versus many different phono stages.

Are you talking about some sort of formal blind testing with multiple participants? Have any links?

 

[wyn palmer]

Are you talking about some sort of formal blind testing with multiple participants? Have any links?

In some cases, yes, in others just the usual audiophile thing, with groups that vary from two or three to a dozen or so. No links as these were not paper-worthy.
I was present for a few, but not for most that have occurred as they have been scattered to several states and several countries. Sota has also performed its own testing, but I can't speak for them in outlining the details of their evaluations, but it did include quite a bit of comparative listening sessions versus a number of different phono stages.
In fact, it was only after those tests that they decided to adopt the design for their own and proceed with production of two models based on it.
Incidentally, I have only an academic interest in this, and the results- pro or con- are equally valuable. Essentially the goal was to test the applicability, if you will, of the extant metrics for audiophile quality by implementing a design that satisfies them all, but is, in a sense, the anti-Pass and Pro-Putseys approach, and that creates an explicitly neutral design. A phono stage was a good test bed as the high gain requirements tax the ability of the design to meet the extremely demanding specifications needed to satisfy the metrics.
Even then there are those that claim that the sound is improved by, for example, changing the power cord, which is something that the unit was explicitly designed not be sensitive to, so audiophiles will always do their tweaks, apparently. Sota also insisted on changing from a SMPS to a linear supply to satisfy audiophile sensibilities.
The architecture, to my knowledge, is unique in a production environment, and is explicitly structured to make the best use of the available high performance opamps.

 

[oranda]

I disagree. The issue is that usually the wrong things are measured. Crude metrics like THD per se are of essentially zero value, but there are other metrics that are useful- ones that take into account the actual non-linear behavior of the auditory system, that recognize the effects of masking, for example, and the reaction of the system to high order distortion products that are audible down to the threshold of hearing, even in the presence of noise.

I think everything you write here is correct. Yes, hearing is complex. My point that we should not throw out what we hear as valid evidence, even if most of our metrics don't agree. To which you say we need to dig deeper into the data/metrics to understand it. No arguments.

Edit: OK, I think you may be disagreeing with "If measurements were all that mattered..." Ok, fair enough. It's better to say "If most of what we measure is all that mattered.."

 

[cgallery]

Yes, I used a TC-750 for a bit. I found it to be serviceable but veiled and lacking in dynamics. I think you will enjoy the Bugle and be very pleasantly surprised if you perform some of the upgrades.

The differences between phono preamps at a similar price point will be small as the components they use are often of similar quality. Opamps like the OPA1612 and OPA2210 will be better than the ones that come in most gear, as are the mentioned capacitors.

Please let us know how you like the stock Bugle and how it improves if you decide to mod it. Cheers!

I only had time to listen to one album w/ the stock Bugle last night, but it did put a smile on my face.

I think the TC-750 can make massed strings (and certain vocals) sound a bit like a low-resolution digital file, so I spun Colin Davis conducting the London Symphony Orchestra's Beethoven No. 7 (Philips 9500 219).

It impressed. I look forward to more listening before contemplating modifications.

 

[oranda]

It impressed. I look forward to more listening before contemplating modifications.

Looking forward to more opinions.

 

[wyn palmer]

I think everything you write here is correct. Yes, hearing is complex. My point that we should not throw out what we hear as valid evidence, even if most of our metrics don't agree. To which you say we need to dig deeper into the data/metrics to understand it. No arguments.

Edit: OK, I think you may be disagreeing with "If measurements were all that mattered..." Ok, fair enough. It's better to say "If most of what we measure is all that mattered.." It just doesn't roll off the tongue as nicely.

The aspects of this are legion. For example- residual distortion tests clearly indicate that polypropylene caps are superior to polystyrene in terms of total distortion,
Measured Differences Between Capacitors for Audio Applications (conradhoffman.com)
and my own distortion and dielectric absorption measurements indicate that PP and C0G appear to be essentially equivalent, with some small variation between manufacturers, yet in this thread a clear preference for polystyrene is expressed, at least for some locations.
Also, issues such as the proper decoupling/supply filtering configuration for the opamps needs to be considered- something that Hagerman attempts to do but, frankly, misses the mark, at least for a number of modern low distortion audio opamps that employ distortion reduction techniques.

 

[cgallery]

The aspects of this are legion. For example- residual distortion tests clearly indicate that polypropylene caps are superior to polystyrene in terms of total distortion,
Measured Differences Between Capacitors for Audio Applications (conradhoffman.com)
and my own distortion and dielectric absorption measurements indicate that PP and C0G appear to be essentially equivalent, with some small variation between manufacturers, yet in this thread a clear preference for polystyrene is expressed, at least for some locations.
Also, issues such as the proper decoupling/supply filtering configuration for the opamps needs to be considered- something that Hagerman attempts to do but, frankly, misses the mark, at least for a number of modern low distortion audio opamps that employ distortion reduction techniques.

Would the stock LM4562 be among the list of modern op amps employing distortion reduction techniques?