Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Reduction => Topic started by: tjessen on September 21, 2014, 02:33:04 PM
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Hello,
I've completed my Reduction build and have come across a problem. My Reduction is not putting out a line level signal, but one that is much quieter. All of my voltages are good and the LEDs and tubes light up well. I have checked my solder connections on the output components of the amplifier circuit, and everything seems well. It is connected to a MM cartridge and I have tried it with my receiver and headphone amp, and compared it to another phono preamp. It just seems way too quiet.
Any ideas?
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The Reduction has 36dB of gain, which is at the lower end for phono stages. So you may well find it quieter than another phono stage, as I did. If it works fine just accept that a higher volume is needed on your amp. Also depends on the output of your cartridge.
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I have my Reduction plugged into my Crack, a combination I was told is suitable. Do I need a preamp?
My cartridge outputs 5mV.
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Reduction into Crack is fine, where is the volume knob at your normal listening levels? Btw, the Integration kit adds more gain, about another 4dB.
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I cannot get to my normal listening volume when the pot is turned completely, and by then there is too much noise in the system.
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What is the nominal output level of your cartridge?
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What is the nominal output level of your cartridge?
As in 5mV +-2db? I'm fairly new to this. It's the music hall tracker.
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That should be giving you pretty close to 1/2 a volt of output. Which will sound lower than a typical digital source, but still be able to play pretty loud on most gear. If the level is just somewhat (I dunno, maybe 1/4-1/3 turn of the volume control?) different then it is probably working as designed. The gain is 36dB which is lower than some other phono preamps. If it is way too low, like you turn the volume up all the way and you can barely hear it, then there is probably a miswire in the preamp.
A lot of this has to do with what gear it is working with and what kind of gain the other components have. What preamp, amp and speakers are you using?
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I'm going to check everything in the amp in the morning, and I'll get back. I truly appreciate the help. I've noticed one channel is currently dead. Better get to work!
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I cannot get to my normal listening volume when the pot is turned completely, and by then there is too much noise in the system.
That doesn't sound correct, as Doc says, there many variables but you should get more volume than that.
Yes, check over the wiring, parts in the correct place, etc
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Ok, I've found that I soldered the one lead of a filter cap to 10L instead of 11, and will fix that asap.
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So I've fixed my capacitor and both channels are good to go, however the amp is still too quiet. Hmmm.
If this is identifiable in both channels and my voltages are checking in, where might I find the problem? Also, the small capacitors are .22uf 250V, unlike the specified .01 uf 400V specified in the manual. Come to think of it that's quite a difference, is this the source of my problem? All 8 are .22uf 250V.
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Just to put it in perspective, what source have you used before the Reduction and where on the volume, i.e. 9:00 or 12:00, did you listen to it?
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The .22µFs are a packing error. We will send you the correct parts. It would help to know who you are (see rule 1 http://bottlehead.com/smf/index.php?topic=3.0 (http://bottlehead.com/smf/index.php?topic=3.0) ).
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Just to put it in perspective, what source have you used before the Reduction and where on the volume, i.e. 9:00 or 12:00, did you listen to it?
Err6tt
Before the Reduction, I would run my DAC with volume at 30%.
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The .22µFs are a packing error. We will send you the correct parts. It would help to know who you are (see rule 1 http://bottlehead.com/smf/index.php?
More replacement parts :(. Alright, I'll get in touch with shipping. Thanks! The additional capacitance explains the volume being sunk into them.
(http://bottlehead.com/smf/index.php?topic=3.0)
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It sounds like your system has enough gain. Not knowing where the mispacked caps go I can't answer if they are drawing down the volume. I'm sure someone else will let you know.
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It sounds like your system has enough gain. Not knowing where the mispacked caps go I can't answer if they are drawing down the volume. I'm sure someone else will let you know.
The caps are for signal filtering/equalization, so I assume so.
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The Reduction RIAA equalization, like the Eros and Seduction, is between the first and second stage. It sends frequency selective signals to ground. With too large a value it might send so much that your volume is compromised.
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Woah golly, yeah, 0.2uF instead of 0.01uF is going to cause all sorts of problems!
Thanks for popping your name on your signature. When we see threads like this on the forum and it's obvious that a care package is necessary, we can just pop it out without asking 20 questions or waiting for an official request.
(Also, if the gain is still too low with the correct EQ, the Integration will raise the gain a bit)
-PB
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So I received my replacement capacitors in the mail today, and with them installed the Reduction is much louder. I send thanks to everyone who assisted me! However, normally listening volume with my reduction plugged into my Crack has me turning the potentiometer to max. Is this normal? If so what do you guys recommend I do to boost the volume. I feel the integration upgrade will not raise the gain enough. Will a preamp do the trick?
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I hate to suggest this, it will become a can of worms :^) - but rewiring the Crack for a 6922 in place of the 12AU7 would give nearly 6dB more gain. Add the 4dB from the Integration and you would have 10dB, about 80 degrees of knob rotation. Speedball should add a bit of gain to the Crack as well, I'm not sure how much.
The technical part is that the 6922 runs at the same plate current, plate voltage, and bias (LED) as the 12AU7. This is an unusual coincidence!
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How much music have you listened to with it? How many different records have you tried? Mastering levels will vary greatly; if you've only listened to one quietly mastered record, you could be skewing your results.
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The stock Crack 12AU7 uses a 6.3V heater, the heater wiring would need to be changed to use a 6922.
I hate to suggest this, it will become a can of worms :^) - but rewiring the Crack for a 6922 in place of the 12AU7 would give nearly 6dB more gain.
The technical part is that the 6922 runs at the same plate current, plate voltage, and bias (LED) as the 12AU7. This is an unusual coincidence!
Not to open the can of worms too much PJ ;D, but would pin9 be used for a 6922?
So I received my replacement capacitors in the mail today, and with them installed the Reduction is much louder. I send thanks to everyone who assisted me! However, normally listening volume with my reduction plugged into my Crack has me turning the potentiometer to max. Is this normal? If so what do you guys recommend I do to boost the volume. I feel the integration upgrade will not raise the gain enough. Will a preamp do the trick?
Hi Trent, good to hear you got it fixed. I found with the stock Reduction, I was getting to about 2o'clock on the volume on my Crack+Speedball into 250Ω Beyers. Adding the Integration bought that back to nearer 12o'clock on the volume knob, so a noticeable increase in gain.
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I do not have the budget required to order the integration at the moment, so would the re-wire provide enough gain? Also what are some recommendations on 6922s?
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Also, I still wish to use my Crack with my DAC, and i listen within 90 degrees of silent. Will I get enough control in my volume with the 6922?
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Also, I still wish to use my Crack with my DAC, and i listen within 90 degrees of silent. Will I get enough control in my volume with the 6922?
I've built a Crack a long, long time ago using a 6922. The gain was overwhelming with any modern source components I had.
The Speedball and Integration will give you some additional headroom.
-PB
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I've got the speedball, I may consider a preamp in my system. Any suggestions? I'm thinking of straying away from tubes though :/
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The 6922 mod is not complicated; just wire the heater power to pins 4 and 5 instead of 4/5 and 9 for the 12AU7. The other pins (1,2,3,6,7,8) remain the same. Leave pin 9 floating. Once done, the 6AU7 is a drop-in replacement for the 6922, if you want to compare over the long term.
However, the 6922 has a greater need for caution about oscillation; I would use grid and plate stoppers as in the Reduction - of course I AM a very cautious engineer! It will make about as much difference as Integration and Speedball combined, at the cost of an inch or two of solder plus a 6922 or 6DJ8. If you try it, use any old 6922 or 6DJ8 available cheap; if you then like it you can explore better tubes for the fun of it. I did tell you it's a can of worms, didn't I?
The mismatch of analog and digital loudness is a very frustrating problem, which has come up now and then ever since the original Seduction 12 years ago. In theory, and with well-recorded music as documented in the professional audio literature, and compared to digital sources that follow the Redbook standards, Reduction should make about the same loudness level as digital sources. Far too often this does not seem to be the case, and I do not have enough data available to me to determine why. Here is a short list of the three most plausible explanations:
1. The phonograph recording is made at a substantially lower "maximum VU" level than the standard 5cm/sec velocity
2. The digital full-scale (FS) output exceeds the Redbook standard of 2.0 volts RMS
3. The digital recording is more aggressively compressed than the phonograph recording
There is a lot of ranting on the web about excessively compressed digital audio, but I've never seen a good statistical analysis to quantify the problem so I can't say if that's the main issue or not. As I said, very frustrating for an engineer!
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However, normally listening volume with my reduction plugged into my Crack has me turning the potentiometer to max. Is this normal?
The position of the volume knob really doesn't matter. When you turn it up all the way, is that below the volume you would like to listen at? If so, then there's a problem to address. If not, just listen and move on. Also you never said if you had tried different records. Since you've had it running for less than a day, it's unlikely that you've spent many hours listening to a variety of music.
Have you used your current cartridge setup with other phono preamps? Have you used your Reduction in any other systems besides the Crack? It's possible that your Reduction still has an issue. One way of testing would be to download a 60Hz tone, adjust your computer's output to be exactly 5mV, then feed it into the Reduction and measure the output with your meter set to VAC. That could tell if something is still amiss.
Furthermore, you've never said what headphones you are using. Is this possibly a non-ideal situation?
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I've compared Reduction to another phono preamp and it delivers a similar gain. I've spent about 6 hours now with my Reduction and many different recordings and for the most time the volume delivered is sufficient, I just wish for a little more on certain recordings or as my listening session progresses. I'm running a pair of hd650s and a Tung Sol 5998 which seemed to raise the gain. I've also used it with my speakers, and it achieves similar loudness to my other phono pre (40/42ish db gain). It seems up to industry standards, I just want more loudness in my system.
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If you just want a little more volume the Integration would probably be the best solution. You could also try a 5998 in place of the 6080 in the Crack, as it has a smaller magnitude negative gain (meaning it makes the Crack a little more sensitive)
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I'm building a preamp to use in my speaker system and will see how it performs with my vinyl rig and Crack. Right now the noise coming from the Crack is quite audible when listening to lps so I'm hoping the preamp will work well in the system. Thanks for all of the suggestions! I hope you Canadians had a wonderful Thanksgiving.
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Hi all,
I'm jumping onto this thread as I was just about to start up a similar one. I finished my Reduction (Integration upgrade built but installation pending a first listen without, per forum advice a few months ago) and finally received my Pro-Ject 2Xperience Classic with Sumico Blue Point No. 2 High Output MC cartridge. This is my first turntable in 20 years, so I have no other point of reference.
For several months, my setup has been Sonos -> Arcam rDAC -> Steremour -> Orcas + Dungeness. Now I swapped the input to Pro-Ject/Sumico -> Reduction -> Steremour. My immediate reaction was the same: way too quiet. I used to listen to the Steremour at about 12:00 when sitting at my desk (1m from the Orcas). I could listen to it at 100% without any earbleed, but that really was too LOUD.
Now, with the Reduction, I am listening at 90%-100%. With many records, even 100% leaves me looking for more volume. This is based on a sample of about 20 rock LPs from the '60s and '70s, and a few remastered jazz LPs. For example, the remastered 180gm Sketches of Spain is FAR too quiet to enjoy, as is an original 1971 pressing of Led Zeppelin III (which was still sealed until yesterday!).
I will try the Integration upgrade immediately, but I'm also wondering if there is another unit I can add to the signal chain to get more output?
Also, I'm thinking I just need to build a second system, i.e. keep the Steremour and Orcas in my smaller study, and build a set of Paramours for 5" Mako standmounts in my large living room, for use with the turntable. I'm wondering if the 9W output and slightly more sensitive speakers will be substantially different?
Any ideas are much appreciated.
Thanks,
Derek
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You really need to put the Integration in before you can make a determination because it will increase the output. The 2.5mV Sumiko output is right at low end of what we recommend using with the Reduction. If the Integration doesn't get you up to where you feel the level needs to be, a Quickie added after the Reduction will boost the signal level a bit more.
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Super. Will look into the quickie and will consider whether there's an easy-ish upgrade path (swap) for my cartridge.
Thanks,
Derek
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You're situation is flawlessly exact of mine Derek. Let us know how any solution you decide upon performs, I'm considering a preamp.
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I'm heading out today to swap out the cartridge. I figure it's the first place to start, getting something that puts out 5mV. Then I'll add the Integration upgrade. I'll let you know what cartridge I end up with and how it works out.
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I think that's a wise decision.
-PB
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So, today I had the hi-fi shop swap my cartridge for an Ortofon 2M Blue (I got some cash back out of the deal!). That definitely helped. For about the same volume that used to be maxed out, the new cartridge had me at about 3:00. Then I installed the Integration upgrade, which dropped the volume knob another "hour," i.e. perhaps to 2:00 for the same volume.
So the good news is I'm getting some definite volume out of this setup now! With an original pressing of Van Halen's Diver Down, sitting in the same near-field location as before, I don't need to turn it past 12:00. And putting it through my Crack, going past 12:00 got to be too much.
When I lift the needle off the record, however, a hum becomes quite apparent. I have easily isolated this to the Reduction. Troubleshooting that is likely for another thread...
Now I just need to figure out if I like this cartridge or not. It's my first turntable since I got my first CD player in 1987, so I don't have a lot to compare it to. But overall, I'm very glad im getting back into vinyl.
Derek
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Have you shorted the inputs on the Reduction? Hum is frequently introduced by the cartridge/arm. Those. Ortofons are particularly problematic with the shield screw on top of the cart body creating more problems than it solves...
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First I turned off the turntable. Then I disconnected it. Then I shorted the inputs. Still no change. When I turn off the Reduction, the Crack goes dead silent (unless I crank it up louder than I would never listen to it anyway -- at about 75% volume, i.e. 3:00, an audible buzz shows up in the Crack).
With the Reduction (post-Integration upgrade; I don't know if this was a problem before, as I only tested with the Steremour and I was dealing with the volume issue), as soon as I turn it on (even with inputs shorted), I hear a definite hiss in both channels. Then, within maybe half a minute, a hum shows up in the left channel, and a few seconds later in the right channel. All this is quite noticeable with the volume knob on either the Crack or the Steremour in my normal listening position, about 12:00. And again, turning off the Reduction makes both amps go dead silent.
(I hope my use of the words buzz, hiss, and hum are descriptive enough...)
Thanks,
Derek
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Hi again,
Please let me know if I should start a new thread on the hum question. A search through the forum for "hum" didn't bring up a lot. There's plenty on hiss, and for that I'll let the tubes run in and see how it sounds in a few weeks.
The hum (maybe 60Hz, could be 120Hz -- I don't know) is something I'd really like to get rid of. When I did the voltage test I noticed the LEDs (both on the PCBs and those surrounding the tubes) light up "group by group." The appearance of hum follows that order (first left, then right).
Is the positioning of the leads which connect the PCBs important? (I.e. should I move them far away from the tubes beneath them?) I'm quite sure I have solid solder connections throughout, as I did everything incredibly methodically and very slowly, visual inspection reveals no issues, and resistance and voltage checks are good. At this point I have no new ideas so any input is highly appreciated.
Thanks,
Derek
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A new thread is a good idea, this one is getting clumsy to scroll through.
Start with a post that describes the system, from turntable to speakers, and why you think the hum originates in the Reduction (i.e. what tests you have already done and their outcome). This will give us a good starting point. A photo showing the location of the components would be a help too.
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Hi,
Rather than start a new thread, I just wanted to let any future readers know that my hum and buzz issues were NOT due the Reduction. I did some more troubleshooting and identified some setup issues (turntable grounding, poor stock phono cable, and signal cable routing issues). So all appears OK with my amp!
To return to the original thread, with a higher output cartridge and the Integration upgrade, the line level out of the Reduction is exactly where I expected it to be.
Thanks (and sorry for derailing this thread),
Derek
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Woohoo! Thanks for the update, always good to hear when a problem has been successfully diagnosed and treated.
This is one of the most rewarding things about this business, when support from the community leads people to figure stuff out for themselves and then share the knowledge with everyone else.