Some years ago, I built an ESP P06 phono stage, along with the suggested power supply and rumble filter. I've been using it happily ever since. However, I just upgraded speakers and now, I have a few nits to pick. I'm not sure if I'm just listening more closely because of the new speakers, or it they're more transparent, or both. But anyway, there are two issues that I'm now hearing. Both of these go away when switching over to the phono pre in my Yamaha integrated amp, so I therefore know that that P06 is the culprit:
1. Vocals can sound a bit unnatural. Something in the upper mids just isn't quite right, and it can sound a bit nasal.
2. One some records, there is too much bass, and it overwhelms the mids and treble causing it to sound muddy.
The second issue isn't too bad, as I can just turn down the bass on the tone control on my integrated amp. The first though, I have not been able to work around. I obviously could just use the pre in the Yamaha, and be fine. But I think the P06 does outperform the Yamaha in some areas, particularly around dynamics and punch.
The P06 was built with quality parts, including 1% vishay dale metal film resistors throughout, and NE5532P opamps.
I did socket the opamps, so swapping would be easy, although I'm not super hopeful that it would solve the problems. But could be fun to try LM4562 or OPA2134.
I had been using Wharfedale diamond 10.7, and recently moved to the new Zu Dirty Weekend 6. Could this just be a bad match? Are the Zu's that much more transparent, so I'm only now noticing things that have really been there all along?
Any other thoughts, suggestions?
1. Vocals can sound a bit unnatural. Something in the upper mids just isn't quite right, and it can sound a bit nasal.
2. One some records, there is too much bass, and it overwhelms the mids and treble causing it to sound muddy.
The second issue isn't too bad, as I can just turn down the bass on the tone control on my integrated amp. The first though, I have not been able to work around. I obviously could just use the pre in the Yamaha, and be fine. But I think the P06 does outperform the Yamaha in some areas, particularly around dynamics and punch.
The P06 was built with quality parts, including 1% vishay dale metal film resistors throughout, and NE5532P opamps.
I did socket the opamps, so swapping would be easy, although I'm not super hopeful that it would solve the problems. But could be fun to try LM4562 or OPA2134.
I had been using Wharfedale diamond 10.7, and recently moved to the new Zu Dirty Weekend 6. Could this just be a bad match? Are the Zu's that much more transparent, so I'm only now noticing things that have really been there all along?
Any other thoughts, suggestions?
From what I've seen of measurements posted online, Zu speakers are not designed to have very flat frequency response. It seems they're more concerned with high sensitivity.
https://www.stereophile.com/content/zu-essence-loudspeaker-measurements
https://www.audiosciencereview.com/forum/index.php?threads/zu-audio-what-is-going-on.1105/
http://noaudiophile.com/Zu/
What happens if you switch back to the Wharfedale speakers? Does the P06 sound more natural then?
I recently built a P06, and I have a Hagerman Bugle to compare to it, along with a two-opamp RIAA of my own design and a tube phono preamp. Tonally they all sound similar, with very slight differences. I don't think the P06 sounds all that different from the others. I quite like it, actually. I prefer the P06 to the Bugle, but that's just my personal preference.
https://www.stereophile.com/content/zu-essence-loudspeaker-measurements
https://www.audiosciencereview.com/forum/index.php?threads/zu-audio-what-is-going-on.1105/
http://noaudiophile.com/Zu/
What happens if you switch back to the Wharfedale speakers? Does the P06 sound more natural then?
I recently built a P06, and I have a Hagerman Bugle to compare to it, along with a two-opamp RIAA of my own design and a tube phono preamp. Tonally they all sound similar, with very slight differences. I don't think the P06 sounds all that different from the others. I quite like it, actually. I prefer the P06 to the Bugle, but that's just my personal preference.
1. might be due to a different input capacitance. With a moving-magnet cartridge, the response above 10 kHz is quite sensitive to the capacitance loading the cartridge.
I have to say, that the review link ( http://noaudiophile.com/Zu/ ) reveals a LOT of flaws/mistakes of this speaker system.
And the manufacturer DARES to price this mess at $5000?
Crap.
Utter insanity.
I've seen better designs from those cheap towers from Parts Express.
Also, and just as important, is the poorly-designed build quality.
Decades ago, it was discussed that dimensions of a speaker cabinet are NOT to be of the same size.
Because that creates irritating standing waves and reflections inside the cabinet.
This contraption is 12" deep by 12" wide - a BIG no-no!
I'd send those units back to where they came from, pronto.
And the manufacturer DARES to price this mess at $5000?
Crap.
Utter insanity.
I've seen better designs from those cheap towers from Parts Express.
Also, and just as important, is the poorly-designed build quality.
Decades ago, it was discussed that dimensions of a speaker cabinet are NOT to be of the same size.
Because that creates irritating standing waves and reflections inside the cabinet.
This contraption is 12" deep by 12" wide - a BIG no-no!
I'd send those units back to where they came from, pronto.
Did you measure the RIAA capacitors for value? The 1% resistors are of no use if the capacitors are 5% or 10%.
The loading on the audio outputs should be fairly high, greater than 25k (preferably more than 75k),
due to the unbuffered passive output LP filter, which sets the RIAA 75uS time constant.
Connecting a 10k load will throw the 75uS way off.
The loading on the audio outputs should be fairly high, greater than 25k (preferably more than 75k),
due to the unbuffered passive output LP filter, which sets the RIAA 75uS time constant.
Connecting a 10k load will throw the 75uS way off.
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That review link is talking about a Zu Speaker that I had never actually even heard of, the Zu Essence, which was released in 2009. While there are some similarities between those speakers and my Zu Dirty Weekend 6, they're more different than similar. Both drivers are different, the tweeter isn't even the same kind of driver - the DW6 uses a compression horn loaded tweeter (in fact Zu don't use ribbons at all anymore), the cabinet is a different design, and the porting method is completely different. I also didn't pay anything like $5k for mine - the DW6 starts at $1599.
I will also say that one of the big draws of Zu speakers was the finish. They're in my living room, so I wanted a speaker that looks like a nice piece of furniture, not a black plastic box. I went with a walnut finish, and they are absolutely stunning. It's bookmatched, figured walnut, absolutely beautiful.
So far, on the same electronics, the Zu's outperform the Wharfedales in every way to my ears - and of course they should, at about twice the price. The bass is more extended and textured, the midrange is more detailed, the treble is smoother, and the imaging is significantly better. Once I'm done nitpicking with the phono pre, these aren't going anywhere.
Seems like they've made quite a bit of progress in the last 13 years.
Here's a link to one of the first reviews of the actual speakers I bought:
Attachments
Well that is a great point. I just checked my Mouser order, and some of the caps are in fact 5% and 10%. Seems like I've got some measuring to do.
Measure them all. Sort them into matched pairs. You may need ten or more parts to get reasonable matching.
Then use the matched pair that is closest to the design value for the circuit. Of course, 1% capacitors are best.
Some vendors will supply matched pairs on request, usually for an extra $1 per part, and it's worth it.
It is important that the stereo channels are very similar in response, hence the matched pairs.
Polypropylene is best, and some also like polystyrene, but avoid polyester/Mylar types.
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It was the capacitors! I replaced C1, C4, and C5 with new polypropelene caps that I had measured. I bought extra parts, and measured each one. I was able to get C1 and C4 matched, and within the correct value within a tolerance of <.5%. C5 I was able to get within 2% (mouser only had 20% tolerance caps, and buying 10 of them, matching within 2% was the best I could do).
I also measured the capacitors that I removed, and some of them were indeed off by as much as 8% from their stated value.
After making those changes, the two problems described above are gone! I've also confirmed with a spectrum analyzer that the response is much, much flatter than it used to be.
Thanks for the help!
I also measured the capacitors that I removed, and some of them were indeed off by as much as 8% from their stated value.
After making those changes, the two problems described above are gone! I've also confirmed with a spectrum analyzer that the response is much, much flatter than it used to be.
Thanks for the help!
Here are some simple inverse RIAA networks for testing.
Of course, the parts used in them must be quite accurate in value.
http://www.hagtech.com/pdf/iriaa2.pdf
https://sound-au.com/p80-Inverse-RIAA.pdf
https://sound-au.com/project80.htm
Of course, the parts used in them must be quite accurate in value.
http://www.hagtech.com/pdf/iriaa2.pdf
https://sound-au.com/p80-Inverse-RIAA.pdf
https://sound-au.com/project80.htm
Nice! Were you able to pin down how far off the P06 frequency response was with the old caps? More than 1dB? Just 0.5dB?
A single RIAA part that is 10% off, would cause about 0.8dB error, in at least some part of the frequency range.
I wasn't unfortunately. I don't have any test records, so I didn't have a great way of measuring the frequency response to that level of precision. But I can say that both my wife and I immediately agreed that the slightly muddy bloated bass that we'd been hearing has been resolved. It now sounds better with the tone controls flat than it did before, when I'd had to turn the bass down slightly to compensate.
Test records aren't accurate enough. RIAA preamps have to be tested purely electronically
without using a turntable, which will always have its own substantial errors.
without using a turntable, which will always have its own substantial errors.
Agreed.
Each cartridge has its own comfortable loading peculiarities.
And so many variables along the chain of amplification, plus room acoustics - it's impossible to align each one for "perfection"
Hi live42,
re: your comment in your initial post about too much bass.
The designer Rod Elliot provides in his write up of the circuit that it in stock form it has a small bass boost. He also provides a supporting frequency response graph.
I would like to add a comment of my own. I have just resurrected a P06 and P99 filter that I built a few years ago.
When it was first set up back then it was in a a big empty room and was running in to some Jamo Concert 7s with upgraded crossover caps. They were obviously capable of handling the bass boost with ease.
This time it is running into a much smaller setup with bookshelf speakers that cannot go as low as the big Jamos. Recently, at times it seemed the bass was a tad too much for the present much smaller set up.
I have recently found a number of posts by Felix Scerri who has posted a fair bit over the years about the P06 in this and other forums. He has corresponded with the designer Rod Elliot re the bass boost and apparently Rod replied that changing R4 from 180 K to 130 K would help to flatten the stock layout's bass boost.
I have tried 130 K and am at present trialling it with a possible Goldilocks value of 150 K for R4. You may be satisfied with the bass the way it is now you have the caps sorted but I thought that information re R4 may be of interest to you.
As the previous poster wiseoldtech said there are "so many variables along the chain of amplification".
re: your comment in your initial post about too much bass.
The designer Rod Elliot provides in his write up of the circuit that it in stock form it has a small bass boost. He also provides a supporting frequency response graph.
I would like to add a comment of my own. I have just resurrected a P06 and P99 filter that I built a few years ago.
When it was first set up back then it was in a a big empty room and was running in to some Jamo Concert 7s with upgraded crossover caps. They were obviously capable of handling the bass boost with ease.
This time it is running into a much smaller setup with bookshelf speakers that cannot go as low as the big Jamos. Recently, at times it seemed the bass was a tad too much for the present much smaller set up.
I have recently found a number of posts by Felix Scerri who has posted a fair bit over the years about the P06 in this and other forums. He has corresponded with the designer Rod Elliot re the bass boost and apparently Rod replied that changing R4 from 180 K to 130 K would help to flatten the stock layout's bass boost.
I have tried 130 K and am at present trialling it with a possible Goldilocks value of 150 K for R4. You may be satisfied with the bass the way it is now you have the caps sorted but I thought that information re R4 may be of interest to you.
As the previous poster wiseoldtech said there are "so many variables along the chain of amplification".
I saw in the P06 instructions that R4 can be reduced to 130k to reduce the bass a bit, and after goofing around with the circuit in LTspice I (like aussiehere) decided to use 150k for R4. It's working well for me. Speakers are Snell E/III (floorstanding bass-reflex 8" two-ways).
Greetings! I built a dual phono preamp using two of the ESP 06 boards, each followed by a P99 subsonic filter. Intended for DJ use, with Shure M44G cartridges. I do also use it for normal hi-fi listening. Anyway, I settled on 130k at R4 to reduce the bass bump, find that satisfactory. Set gain resistors to 65k, to compensate for the higher output dj cart. I installed LM4562 opamps for input and output stages. It sounds nice and clean, but a bit too polite. I am going to put in an order for OPA2134, OPA2228, and AD826 opamps. Thinking of just getting one to put at output stage, use LM4562 at input. Besides the three mentioned, are there any other opamps which are worth trying?