DIY Phono Preamp Recommendation

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Thank you very much. I am actually using Denon DL-110 HOMC cartridge.

I googled the phono PCB and is this the one that you are referring to?
3-Valve Phono PCB

Has anyone tried Hagerman Bugle 2? I saw that the shop is selling PCB Kit, too and wondering how this one compares with other Kit such as 3 value phono PCB.

Thank you again.
I have built one of these ( 3-valve PCB), it has a lot of options as regards to
tubes and placement of riaa , i did the most trivial with ECC83 and "all-in-one". I am fully satisfied with the function.
See the build progress at

Merlin 3-valve
 
Last edited:
partly because it doesn't seem to get built, Stu Hegeman's Citation I/IV circuit with cascade feedback pair driving passive RIAA.

Here's one example - I'd probably use small bottles as had way too many microphonic 6SL7s.

Add an "anode-follower" (maybe 12AU7) high level stage to keep it "Hegeman-ish" (and avoid the dreaded :)CF )

https://i.imgur.com/FWOBl.jpg

regarding high Miller capacitance with 12ax7, guess one could use a 12ax7 cascode.
 
Difference between valve and solid state is night and day. Valve gives you much better dynamics and soundstage with the increased dynamic range and overload capability. Be careful with the EAR ... too warm in my opinion. The modified RCA is a great circuit but as mentioned too much capacitive load. If you want a kit, you can't go wrong with Bottlehead. I have heard MANY phono stages and the BigBottle sold here on this site is hard to beat!


Input capacitance of 12ax7 will be no problem with Denon 110 (high-output moving coil).
 
I have built one of these ( 3-valve PCB), it has a lot of options as regards to
tubes and placement of riaa , i did the most trivial with ECC83 and "all-in-one". I am fully satisfied with the function.
See the build progress at

Merlin 3-valve

Nice!

I have a Denon DL110 HOMC, and I like it a lot. It works great with tube preamps because it doesn't get upset by high input capacitance like a moving-magnet or moving-iron cartridge would (e.g., Grado, Nagaoka, Shure or Audio-Technica).

I've used LTspice to simulate my own version of Merlin's 3 tube preamp using a 12AX7 with all-in-one EQ, DC coupled to a 12AT7 cathode follower output stage. LTspice is telling me this can get a nice amount of gain with very low THD.

The version I've settled on will use a red LED in the cathode to bias the input 12AX7. (Following Merlin's suggestion I'll bypass the LED with 220uF to reduce noise.) This first stage is where you want enough gain with lowest noise, but signal level here is so low that THD won't be much of a problem.

The second stage is also a 12AX7, but because this stage will see higher signal levels, this is where most of the THD will happen in this circuit. My solution is to use an unbypassed cathode resistor (no cathode bypass capacitor) here to add current feedback, which reduces both gain and distortion. The unbypassed Rk also raises the output impedance of this stage, but that isn't a problem driving the grid of a 12AT7 cathode follower.

LTspice says this will yield 46dB gain with THD of only about 0.03% at 1V rms output. That's close to solid-state clean. I'm in the process of building the thing. I need to build a regulated 300V DC supply and a 12V DC heater supply. Maybe I'll use an SMPS wall wart for the 12V.

I built an old version Hagerman Bugle, which is very close to the Bugle 2. It's 'drier' sounding than a tube preamp, but pretty good. It's clean and quiet, but not the last word in clarity. Its stock EQ adds a bass roll-off which I don't like. I'd rather the preamp was flat down to 20Hz and let me figure out any mechanical rumble problems.

I also have a Schiit Mani, which sounds pretty similar to the Bugle, but goes deeper in the bass and sounds more 'plump' down there. I think the Bugle is clearer sounding. The Mani is 'warmer' sounding.

I like tube preamps for vinyl though. Done right, tubes have lots of voltage headroom, so you don't get a sense of any limit on dynamics. They will hiss more than a good solid-state preamp, but that's not been a problem for me, at least. Tubes are simply noisier than op-amp ICs.

The main downside of a tube phono preamp is high input capacitance. This can be a problem for moving magnet or moving iron cartridges (can introduce a resonant peak in the high audio band, with a fast roll-off above that), and it can also be a problem for step-up transformers for moving coil cartridges (ringing, unwanted resonance).

IMO, either the Hagerman Bugle 2 or Merlin's 3-tube preamp pcb will be a worthy DIY project. Also Salas' Simplistic NJFET RIAA, which a lot of people really like (I haven't heard one, though.) The Hiraga Le Pacific is worth slapping together, even though it operates at higher levels of THD. You have so many good choices...
--
 
Last edited:
Thank you very much. I am actually using Denon DL-110 HOMC cartridge.

I googled the phono PCB and is this the one that you are referring to?
3-Valve Phono PCB

Has anyone tried Hagerman Bugle 2? I saw that the shop is selling PCB Kit, too and wondering how this one compares with other Kit such as 3 value phono PCB.

Thank you again.

Nice!

I have a Denon DL110 HOMC, and I like it a lot. It works great with tube preamps because it doesn't get upset by high input capacitance like a moving-magnet or moving-iron cartridge would (e.g., Grado, Nagaoka, Shure or Audio-Technica).

I've used LTspice to simulate my own version of Merlin's 3 tube preamp using a 12AX7 with all-in-one EQ, DC coupled to a 12AT7 cathode follower output stage. LTspice is telling me this can get a nice amount of gain with very low THD.

The version I've settled on will use a red LED in the cathode to bias the input 12AX7. (Following Merlin's suggestion I'll bypass the LED with 220uF to reduce noise.) This first stage is where you want enough gain with lowest noise, but signal level here is so low that THD won't be much of a problem.

The second stage is also a 12AX7, but because this stage will see higher signal levels, this is where most of the THD will happen in this circuit. My solution is to use an unbypassed cathode resistor (no cathode bypass capacitor) here to add current feedback, which reduces both gain and distortion. The unbypassed Rk also raises the output impedance of this stage, but that isn't a problem driving the grid of a 12AT7 cathode follower.

LTspice says this will yield 46dB gain with THD of only about 0.03% at 1V rms output. That's close to solid-state clean. I'm in the process of building the thing. I need to build a regulated 300V DC supply and a 12V DC heater supply. Maybe I'll use an SMPS wall wart for the 12V.

I built an old version Hagerman Bugle, which is very close to the Bugle 2. It's 'drier' sounding than a tube preamp, but pretty good. It's clean and quiet, but not the last word in clarity. Its stock EQ adds a bass roll-off which I don't like. I'd rather the preamp was flat down to 20Hz and let me figure out any mechanical rumble problems.

I also have a Schiit Mani, which sounds pretty similar to the Bugle, but goes deeper in the bass and sounds more 'plump' down there. I think the Bugle is clearer sounding. The Mani is 'warmer' sounding.

I like tube preamps for vinyl though. Done right, tubes have lots of voltage headroom, so you don't get a sense of any limit on dynamics. They will hiss more than a good solid-state preamp, but that's not been a problem for me, at least. Tubes are simply noisier than op-amp ICs.

The main downside of a tube phono preamp is high input capacitance. This can be a problem for moving magnet or moving iron cartridges (can introduce a resonant peak in the high audio band, with a fast roll-off above that), and it can also be a problem for step-up transformers for moving coil cartridges (ringing, unwanted resonance).

IMO, either the Hagerman Bugle 2 or Merlin's 3-tube preamp pcb will be a worthy DIY project. Also Salas' Simplistic NJFET RIAA, which a lot of people really like (I haven't heard one, though.) The Hiraga Le Pacific is worth slapping together, even though it operates at higher levels of THD. You have so many good choices...
--
I measured my build of merlin 3-valve riaa to 0.06% , that includes hum
from the board laying on a table and 1Volt output. So yes, it's fairly clean.
 
I measured my build of merlin 3-valve riaa to 0.06% , that includes hum
from the board laying on a table and 1Volt output. So yes, it's fairly clean.

I assume that's THD you measured. Was that measured with 5mV rms input, or with 1V rms at the output?

If with 1V rms output into something like 47k ohms, I'd say that's really good for an all-tube RIAA preamp made with garden-variety guitar amp tubes. ;)

Do you find it sounds a lot different than commercial phono preamps you've heard or used? Just curious to find out how you like it. Also, what phono cartridge do you use with the preamp? If you don't mind my asking...
 
I assume that's THD you measured. Was that measured with 5mV rms input, or with 1V rms at the output?

If with 1V rms output into something like 47k ohms, I'd say that's really good for an all-tube RIAA preamp made with garden-variety guitar amp tubes. ;)

Do you find it sounds a lot different than commercial phono preamps you've heard or used? Just curious to find out how you like it. Also, what phono cartridge do you use with the preamp? If you don't mind my asking...
It was 0.06% THD at 1V out ( 3.7 mV in )
I never connected it to an cartridge but sold it "as is "
 
I assume that's THD you measured. Was that measured with 5mV rms input, or with 1V rms at the output?

If with 1V rms output into something like 47k ohms, I'd say that's really good for an all-tube RIAA preamp made with garden-variety guitar amp tubes. ;)

Do you find it sounds a lot different than commercial phono preamps you've heard or used? Just curious to find out how you like it. Also, what phono cartridge do you use with the preamp? If you don't mind my asking...
It's by the way no "garden-variety guitar amp tubes" it's E83CC framegrid tubes
from JJ ( new production) and E88CC also framegrid tubes.
 
I am looking for recommendations on a significantly improved phono preamp kit for my analog system. The sonic performance is currently really quite good: full bass, good separation and sound stage, and very realistic. Would I be better with a solid state or tube preamp.
(1) Lenco L-75 turntable modified with a custom plinth and Silver Note 512S tone arm. Stanton 681 cartridge with a Pickering 625DJ stylus. I would like the option of upgrade to a moving coil cartridge in the future.
(2) Hagerman, Bugle 2 phono pre-amp
(3) Bottlehead Stereomour 2A3 SE tube amp
(4) Klipsch KLF-20 horn speakers (100dB/m)

Below is a list of the phono pre-amp kits I have found.
(1) RJM, Emerald (RJM Audio)
(2) Elliot, P06 HiFi Phono Preamp (Hi-Fi RIAA Phono Preamp)
(3) Tindie, Muffsy Phono Preamp PP-4 Kit (https://www.muffsy.com/muffsy-pp4)
(4) Pass Labs, Pearl 2 (https://www.passdiy.com/pdf/PEARL 2.pdf)
(5) Signal Transfer, Phono Preamplifier (The Signal Transfer Company: RIAA PCB with unbalanced outputs)
(6) Boozhound, Deluxe Phono Preamp (https://boozhoundlabs.com/collections/all/products/deluxe-phono-peramplifier)
(7) Tavish, Vintage 6SL7 Phono Stage (https://tavishdesign.com/products/vintage-6sl7-phono-stage?variant=13907030662)
(8) GlassWare, Aikido Tetra (https://glass-ware.stores.yahoo.net/tetrasansps.html)
(9) Bottlehead Reduction 1.1 (https://bottlehead.com/product/reduction-1-1-phono-preamplifier-kit/#)
(10) Bottlehead Eros 2 (https://bottlehead.com/product/eros-2-phono-preamplifier-kit/)

Thanks!

I simulated several of the designs you listed, like the Hagerman Bugle 2, Emerald and Muffssy. As expected, looking at the last two designs schematics, frequency response and and THD at the specified frequency, is very similar.

In both cases you should select the output capacitor, preferably a polypropylene film one or better, to set the very low bass response.

If required I can include FR and THD simulations, but they are virtually the same.

Things are different on the Hagerman,which has a pronounced low frequency roll-off which I couldn't figure how to control or set. It starts at 40Hz and falls an almost steady 3dB/octave down to 27dB @ 1Hz.

That will help with turntables rumble and low frequency "flapping" my belt turntables suffer off. I had to use a polystyrene input cap on my cure it. But that is a very low frequency problem, I'd say 3 to 5Hz. Cutting more than that should affect the response of many LPs with more low frequency information. Symphonic orchestras, jazz groups, etc. But you should control that, and I didn't see any bass settings in the Hagerman.
 
Last edited:
I still use a Bugle I built about 15 years ago. It works nicely, although you're right, there's an obvious bass rolloff. You can fix that while you're building it, though. There's an interstage coupling capacitor between the 2nd and 3rd opamps that's specified as 0.22uF. You can increase the C value of that to 0.33uF or 0.47uF and the circuit will go lower. Also, there's a series resistor to the higher frequency shelving network that can be increased slightly in value —8.43k in my original Bugle—which I might increase to 9.1k as an experiment.

I use OPA2134 opamps in my Bugle.
LTspice has an OP134 model, which I used for simulation. I don't know how accurate it is. Basically, the simulation says the standard 40dB gain version is distortionless. In real life? I don't know. Here's a review with measurements of the Bugle2, for what it's worth:

Hagerman Bugle2 DIY Kit Phono Preamp | Audio Science Review (ASR) Forum

The author didn't mention how he was powering the audio circuits, but he did find it was noisy in one channel, which skewed his measurements. I built mine with the Hagtech PSU kit in a separate enclosure, connected by umbilical cord. I don't find the Bugle to be at all noisy. Perhaps running it in a plastic case in a lab with lots of other gear radiating noise skewed the reviewer's results.

FWIW, anyway... I find the Bugle sounds very good, although not as *subjectively* exciting as some of the tube preamps I've used.

Another thing:
I've been fooling around with modeling the effect of cable capacitance and moving magnet cartridge coil inductance on frequency response from the preamp. It looks like any MM cart is going to suffer from a peak in the 8kHz to 15kHz region, with a steep drop in output as you go higher in frequency. That results from the cartridge's inductance interacting with the typical 150pF to 300pF capacitance of the cable connecting the tonearm to the phono preamp inputs. If you have a HOMC like a Denon DL110 or similar, that won't be an issue. But if you're planning to use any of the popular MM carts like Nagaoka, Audio Technica, Goldring, etc. then you'll want to compensate by keeping the input capacitance of your phono preamp very low. That probably disqualifies 12AX7, ECC83, E83CC, ECC803, and so on (input C usually about 200pF at the grid to ground, just from the tube, not including cable capacitance). 6DJ8/ECC88 would be a better choice (usually about 100pF input C). However, I can't seem to find what the input C of an OPA2134 or AD797 is. Anybody know?
--

EDIT:
I attached a predicted frequency response from a preamp design I'm working on that uses a 12AX7 as the input tube.
I found the coil inductance and coil DCR of the Audio Technica VM95 cartridge (L = 550mH, R = 485 ohms), so I put that feeding the input circuit, after the inverse-RIAA.
I also added 150pF in parallel across the input, to simulate cable capacitance.
I ran the simulation and the frequency response shows a +1.1dB peak centered around 10kHz, with the high frequency response diving quickly to -3dB at just shy of 17kHz. That ain't flat!
--
 

Attachments

  • 12AX7_ATVM95.png
    12AX7_ATVM95.png
    17.9 KB · Views: 502
Last edited:
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.