A shunt resistor really won't work there. The only place that it sort of would is after the pot (C20 & C21), but it would cause a really odd attenuation curve (the pot is mostly logarithmic, so a shunt resistor will change the curve quite a lot). But, you can certainly try it. You may find that it will get you low enough gain where you want it...
Pete
The nutube is definitely microphonic. Some maybe more than others? But the voltages you measure are fine.
Most of the fixes I've seen are purely mechanical.
Pete
Hi rikiheck,
Apologies for the delay in replying to your question.
I've got the board populated and the case has arrived. I just need a quiet few hours to put it all together. I'm hoping to get it done in the next couple of weeks. I've used the shop kit with Grado 325s and it sounds really good so I'm itching to see what effect the changes will have.
Apologies for the delay in replying to your question.
I've got the board populated and the case has arrived. I just need a quiet few hours to put it all together. I'm hoping to get it done in the next couple of weeks. I've used the shop kit with Grado 325s and it sounds really good so I'm itching to see what effect the changes will have.
Hey I'm currently having a problem with my starving student 2 amp. It has been running for the past year but now the back tube is overheating. The front tube socket has all measured up okay. But the back tube is measuring at 47v on pins 1, 2, 4 & 7. Does anyone have any clues as to why this would be?
Good morning from New Mexico - I just finished putting together 2 ACA amps (used in mono service) and a SS headphone amp which is being used as a preamp with the ACA amps. 2 questions please: 1st, the ACA amps run hot, not so hot that I cannot touch but hot otherwise. Is this ok? 2nd, I'm using my iPhone as the source and get occasional "clicking" during the playing of a song. It stops after 5 seconds or so. 0the patch cord is a cheapie RCA by mini-plug (new). I've jiggled all hookup wires to no affect. Got any thoughts? thanks, Jon
Hi rikiheck,
The SSII Mark 2 is mostly finished with just a couple of cosmetic issues to address. I'm giving it a couple of days to burn in before comparing it to the Diystore version.
The zip-tie is there to hold the front panel while I wait for some longer screws to arrive. The knob is the one that came with the stepped attenuator and will eventually be replaced with something nicer. (Does anyone know of a supplier of good quality knobs with 6mm D splines?). The front panel will have a finish applied at some point, but I've yet to decide what finish I want.
First impression is of significantly more detail on acoustic instruments. There has been some initial hardness to the sound but that has settled after the first few hours of use. I haven't plugged it into my main system yet, only my desk set-up, so I won't say any more for now.
The SSII Mark 2 is mostly finished with just a couple of cosmetic issues to address. I'm giving it a couple of days to burn in before comparing it to the Diystore version.
The zip-tie is there to hold the front panel while I wait for some longer screws to arrive. The knob is the one that came with the stepped attenuator and will eventually be replaced with something nicer. (Does anyone know of a supplier of good quality knobs with 6mm D splines?). The front panel will have a finish applied at some point, but I've yet to decide what finish I want.
First impression is of significantly more detail on acoustic instruments. There has been some initial hardness to the sound but that has settled after the first few hours of use. I haven't plugged it into my main system yet, only my desk set-up, so I won't say any more for now.
Attachments
Well worth doing!
I've had the opportunity to try out the two versions of the SSII in several systems now. As part of the process, I also took them around to a friend's house and tried them with different speakers, speaker cables and sources while there. My final listening session was in my main system. The source is a Naim CD5 and the speakers are Linn Keilidhs. In all cases I used an ACA for amplification.
I will start by saying that I have enjoyed the stock version a great deal and recommend it as a very worthwhile project. I would not have had the impulse to create the modified version otherwise. This assessment is purely a comparison between the two and not a comparison with other pre-amps. Please note that I am reviewing this as preamp and not as a headphone amp. I will spend some time soon to have an extended listening session via headphones.
I made a point of letting both SSII's warm up for at least 30-40 minutes before sitting down to listen through my main speakers last weekend. I have used the Raytheon tubes/valves in both versions to minimise variations from that part of the circuit.
I made a comment in my last post about a degree of hardness in the sound. I isolated this to the Astell & Kern AK70 that I usually use as a portable music source. It has a line output setting which produced the same 'hardness' in my friend's system. Once noted, I reduced the output a little. This improved the sound significantly.
The stock version has a very agreeable character that has made it a good addition to my office set-up. This uses a pair of Q Acoustics 2020i speakers in near field setup. As they are only two feet away from my head, any harshness is not easily tolerated. Since high volumes aren’t required, the ACA doesn’t get stressed either. There is plenty of information provided in this set-up but very little soundstage due to the positioning of the speakers. I play a wide range of music from light classical (very little) through to heavy rock. I lean more to prog rock and well-played blues, so the music ranges from simple acoustic to heavily produced.
Within the limitations of the relatively small speakers, the stock version works well. The bass has good depth but not earth-shaking, and the treble is easy on the ear and has a good amount of detail. It is an arrangement that I can listen to for several hours at a time while working at my desk and has been used for several months now. It is especially good when listening to acoustic guitar or female voices, to the extent that I can easily get distracted from the work that I should be doing!
Listening to the stock version at my friend’s house produced similar results. His B&W speakers are close in size to the Q2020i. His other speakers are a Scanspeak DIY kit which are only slightly larger but much more revealing. In this set up I noticed that the stock version began to sound muddled and it was difficult to place instruments. Switching to the modded version quickly demonstrated more detail and emotional insight to the music. I made a point of not discussing my opinion of the sound before my friend had given his. His summation was that was “more pleasing and engaging.” There was significantly more ‘leading edge’ or attack to each note and not in a distracting way. There was an increase in dynamic range, better bass control and a little bit more depth. In that set-up, we couldn’t discern a great deal of difference in the range of the treble though.
The most fun has been had in the final listening session through the Keilidhs. I have used the ACA with these before, mostly with a Naim preamp, but also with an Aksa Lender pre in the last few months. So I have a good measure of the ACA/Keilidh combination. As mentioned before, the source was a Naim CD5 and both versions of the SSII were given plenty of warm up time.
In this set-up the differences in sound were much greater. The stock version worked well enough at lower volumes but instruments would become difficult to isolate and follow if the volume increased or the music became more complex. The bass had little impact and the treble very smeared. This was the case even with relatively simple recordings, one example being a string quartet.
Swapping to the modded version, the muddle was greatly reduced; even during it’s warm up phase. After 30 or so minutes of warm up it was all but gone. The sound remained characterful, like the stock version, but the bass was much more palpable and distinct. Toe-tapping is still a very good way of judging how involving a system is and I noticed that I was ‘tapping’ from the very first track played.
It noticeable came ’on song’ after about 45-50 minutes. The rhythms became easier to follow; voices had separation and well defined locations. Bass instruments had power and projection. The treble still doesn’t have the extension that we expect from transistors design, but there is plenty of detail to follow and enjoy. The most enjoyable track of this listening session was ‘Homeless’ from Paul Simon’s ‘Graceland.’ The sound was nicely balanced from bass through mid-range to the slightly rolled off treble. This is combination that is far from neutral, but one that I could listen to all day long. They was soooo much atmosphere and emotion in this track that it made the whole process of making this modded version worthwhile all on its own.
To restate, the stock version is still a kit that I thoroughly recommend to anyone. It is professionally manufactured and straightforward to assemble. It is very enjoyable to listen to and should take less than a day to finish. Producing my modded version involved obtaining all the parts, hook-up wires, enclosures and the like. Then you have to measure up and cut your own holes (not as easy as it seems!) and make an agreeable looking package. I estimate the cost of my modded version at about £140-£150 but then there have been many more hours used up in its production compared to the kit. Routing solid oak was a learning experience, as I have been used to routing plywood, MDF and softwoods. It is a lot harder, literally and figuratively. Waiting for the cheaper aluminium enclosure from a Chinese eBay vendor is measured in weeks and not days. The finish is not as good as the HiFi2000 cases. You pay only a little more for a great deal more convenience when you get the kit from the diyAudio store.
Thank you again to Peter for sharing your designs with the DIY community. I shall enjoy this preamp for many years to come.
I've had the opportunity to try out the two versions of the SSII in several systems now. As part of the process, I also took them around to a friend's house and tried them with different speakers, speaker cables and sources while there. My final listening session was in my main system. The source is a Naim CD5 and the speakers are Linn Keilidhs. In all cases I used an ACA for amplification.
I will start by saying that I have enjoyed the stock version a great deal and recommend it as a very worthwhile project. I would not have had the impulse to create the modified version otherwise. This assessment is purely a comparison between the two and not a comparison with other pre-amps. Please note that I am reviewing this as preamp and not as a headphone amp. I will spend some time soon to have an extended listening session via headphones.
I made a point of letting both SSII's warm up for at least 30-40 minutes before sitting down to listen through my main speakers last weekend. I have used the Raytheon tubes/valves in both versions to minimise variations from that part of the circuit.
I made a comment in my last post about a degree of hardness in the sound. I isolated this to the Astell & Kern AK70 that I usually use as a portable music source. It has a line output setting which produced the same 'hardness' in my friend's system. Once noted, I reduced the output a little. This improved the sound significantly.
The stock version has a very agreeable character that has made it a good addition to my office set-up. This uses a pair of Q Acoustics 2020i speakers in near field setup. As they are only two feet away from my head, any harshness is not easily tolerated. Since high volumes aren’t required, the ACA doesn’t get stressed either. There is plenty of information provided in this set-up but very little soundstage due to the positioning of the speakers. I play a wide range of music from light classical (very little) through to heavy rock. I lean more to prog rock and well-played blues, so the music ranges from simple acoustic to heavily produced.
Within the limitations of the relatively small speakers, the stock version works well. The bass has good depth but not earth-shaking, and the treble is easy on the ear and has a good amount of detail. It is an arrangement that I can listen to for several hours at a time while working at my desk and has been used for several months now. It is especially good when listening to acoustic guitar or female voices, to the extent that I can easily get distracted from the work that I should be doing!
Listening to the stock version at my friend’s house produced similar results. His B&W speakers are close in size to the Q2020i. His other speakers are a Scanspeak DIY kit which are only slightly larger but much more revealing. In this set up I noticed that the stock version began to sound muddled and it was difficult to place instruments. Switching to the modded version quickly demonstrated more detail and emotional insight to the music. I made a point of not discussing my opinion of the sound before my friend had given his. His summation was that was “more pleasing and engaging.” There was significantly more ‘leading edge’ or attack to each note and not in a distracting way. There was an increase in dynamic range, better bass control and a little bit more depth. In that set-up, we couldn’t discern a great deal of difference in the range of the treble though.
The most fun has been had in the final listening session through the Keilidhs. I have used the ACA with these before, mostly with a Naim preamp, but also with an Aksa Lender pre in the last few months. So I have a good measure of the ACA/Keilidh combination. As mentioned before, the source was a Naim CD5 and both versions of the SSII were given plenty of warm up time.
In this set-up the differences in sound were much greater. The stock version worked well enough at lower volumes but instruments would become difficult to isolate and follow if the volume increased or the music became more complex. The bass had little impact and the treble very smeared. This was the case even with relatively simple recordings, one example being a string quartet.
Swapping to the modded version, the muddle was greatly reduced; even during it’s warm up phase. After 30 or so minutes of warm up it was all but gone. The sound remained characterful, like the stock version, but the bass was much more palpable and distinct. Toe-tapping is still a very good way of judging how involving a system is and I noticed that I was ‘tapping’ from the very first track played.
It noticeable came ’on song’ after about 45-50 minutes. The rhythms became easier to follow; voices had separation and well defined locations. Bass instruments had power and projection. The treble still doesn’t have the extension that we expect from transistors design, but there is plenty of detail to follow and enjoy. The most enjoyable track of this listening session was ‘Homeless’ from Paul Simon’s ‘Graceland.’ The sound was nicely balanced from bass through mid-range to the slightly rolled off treble. This is combination that is far from neutral, but one that I could listen to all day long. They was soooo much atmosphere and emotion in this track that it made the whole process of making this modded version worthwhile all on its own.
To restate, the stock version is still a kit that I thoroughly recommend to anyone. It is professionally manufactured and straightforward to assemble. It is very enjoyable to listen to and should take less than a day to finish. Producing my modded version involved obtaining all the parts, hook-up wires, enclosures and the like. Then you have to measure up and cut your own holes (not as easy as it seems!) and make an agreeable looking package. I estimate the cost of my modded version at about £140-£150 but then there have been many more hours used up in its production compared to the kit. Routing solid oak was a learning experience, as I have been used to routing plywood, MDF and softwoods. It is a lot harder, literally and figuratively. Waiting for the cheaper aluminium enclosure from a Chinese eBay vendor is measured in weeks and not days. The finish is not as good as the HiFi2000 cases. You pay only a little more for a great deal more convenience when you get the kit from the diyAudio store.
Thank you again to Peter for sharing your designs with the DIY community. I shall enjoy this preamp for many years to come.
Finally finished the exterior of my case with some Danish Oil on the oak front. The little black knob was the best of what I could find for a 6mm d shaft. I must make sure that I check the shaft size before ordering next time (no innuendo intended, honest).
Attachments
Last edited:
Looks great! I built mine stock but into a custom case, as well.
(Full size image: http://rkheck.frege.org/images/wood/SSII-03.jpg).
An externally hosted image should be here but it was not working when we last tested it.
(Full size image: http://rkheck.frege.org/images/wood/SSII-03.jpg).
Last edited:
Hey, I assembled everything according to the guide. When I do a smoke test I get around 42V on both pin3 and only the LEDs inside the tube sockets are lighting up. When I plug it it I hear a lot of cracking. I re soldered everything but I still get the above voltage. What can I do to find the issue?
Just FYI, I initially had very bad microphonic issues with the Raytheon tubes supplied with the kit. Ringing when turning the volume control, or tapping the case, or even when the cord would sway when I was listening.''
I tried a different pair of Raytheons from EBay. No difference. Then tired a pair of RCA tubes. Problem gone.
I don't (yet) have a view about other differences between these tubes. The RCAs are clearly better for me, so not much motivation...
I tried a different pair of Raytheons from EBay. No difference. Then tired a pair of RCA tubes. Problem gone.
I don't (yet) have a view about other differences between these tubes. The RCAs are clearly better for me, so not much motivation...
First experience of Tube/Valve rolling.
I've been using both iterations of my SSII with the Raytheon tubes for a while now. I hadn't got around to trying some of the other valves from the rolling kit that Peter Millett sent me last year.
I've only tried the Tung-Sol so far. What a difference! I was only expecting minor differences in character, so initially I was only intending to listen casually whilst doing some domestic admin. Six hours later and a lot less domestic admin than planned...
I only stopped because I suddenly realised what the time was and the battery on my AK70 was nearly empty. It is so much cleaner and exciting following the valve swap. Ridiculous amounts of low level detail from tracks I thought I knew well.
Goosebumps and foot-tapping, 'nuff said! Thanks again to Peter Millett and the DiyAudio store!
I've been using both iterations of my SSII with the Raytheon tubes for a while now. I hadn't got around to trying some of the other valves from the rolling kit that Peter Millett sent me last year.
I've only tried the Tung-Sol so far. What a difference! I was only expecting minor differences in character, so initially I was only intending to listen casually whilst doing some domestic admin. Six hours later and a lot less domestic admin than planned...
I only stopped because I suddenly realised what the time was and the battery on my AK70 was nearly empty. It is so much cleaner and exciting following the valve swap. Ridiculous amounts of low level detail from tracks I thought I knew well.
Goosebumps and foot-tapping, 'nuff said! Thanks again to Peter Millett and the DiyAudio store!
Hello,
I have a problem. When I do a smoke test I get around 43V on both pin3. I checked all my connections for shorts and cold soldering. I re soldered everything and removed the capacitors and checked if they are ok.
Looking at the circuit plan I assume my mosfets are broken when the voltage is not right at pin3. I don't know how to check them, only guide I found says there has to be a high ohm resistor between the pins, which is the case.
I assume some parts are broken, if it is not the mosfets how can I find the broken parts? Thank you.
I have a problem. When I do a smoke test I get around 43V on both pin3. I checked all my connections for shorts and cold soldering. I re soldered everything and removed the capacitors and checked if they are ok.
Looking at the circuit plan I assume my mosfets are broken when the voltage is not right at pin3. I don't know how to check them, only guide I found says there has to be a high ohm resistor between the pins, which is the case.
I assume some parts are broken, if it is not the mosfets how can I find the broken parts? Thank you.
I’ve been bothered by a slight ‘bathroom’ effect to the sound of mine - like listening in a tiled room rather than with soft surfaces, smearing detail, if that makes sense.
I initially thought it was my headphones (dt150), so did some work on those to good effect, but the big difference was changing the caps in the signal path.
I’ve swapped out the wimas to better films, and c1 & 2 to np muses.
What a difference!
All the reverberant effect has gone, the imaging is much more ‘planted’, everything is so much more real (imho).
If my experience is anything to go on, a change very well worth considering!
Dave
I initially thought it was my headphones (dt150), so did some work on those to good effect, but the big difference was changing the caps in the signal path.
I’ve swapped out the wimas to better films, and c1 & 2 to np muses.
What a difference!
All the reverberant effect has gone, the imaging is much more ‘planted’, everything is so much more real (imho).
If my experience is anything to go on, a change very well worth considering!
Dave
I've been using both iterations of my SSII with the Raytheon tubes for a while now. I hadn't got around to trying some of the other valves from the rolling kit that Peter Millett sent me last year.
I've only tried the Tung-Sol so far. What a difference! I was only expecting minor differences in character, so initially I was only intending to listen casually whilst doing some domestic admin. Six hours later and a lot less domestic admin than planned...
I only stopped because I suddenly realised what the time was and the battery on my AK70 was nearly empty. It is so much cleaner and exciting following the valve swap. Ridiculous amounts of low level detail from tracks I thought I knew well.
Goosebumps and foot-tapping, 'nuff said! Thanks again to Peter Millett and the DiyAudio store!
That sounds interesting!
Unfortunately the diyaudiostore is sold out - anyone know of a source, preferably uk?
Dave