Steve Toy
23-06-2008, 15:33
It was a gamble as I was buying an amp with the intention of having it modified from the outset without knowing exactly how it was going to turn out. I'm not really into leaps of faith but having heard the Chinese Yaqin amp in my own system with which I was extremely impressed, I thought I had to have something at least similar.
The problem with the Yaqin was that it needed a step-down transformer to work safely with UK voltages and I didn't fancy this option. As good as the Yaqin sounded, the mains transformers are wound for 220 volt not the 240 for the UK where voltages have been known to push towards the 250 mark. Hook up a Yaqin or some other Chinese import here and you may get the fireworks to accompany your music before the music stops. This has already happened to at least one person...
Our resident electronics engineer and valve specialist Anthony even advised not to even switch such an amp on until someone like himself had had a good look at it and made sure it was safe. Thus from a purely safety angle my only option if I wanted a Chinese-built valve amp was to go for one with mains transformers specified for the UK. Two options sprang to mind: something from Prima Luna or the Puresound amps imported and made safe by Guy Sergeant based on but quite different to the Bewitch available for about the same money as the Yaqin. Ok, for the luxury of made-for-UK reassurance I was paying £1100 instead of under £400. Some of the price difference obviously included distributor and dealer mark-ups but I think this was definitely one instance where such middle men were adding value to my purchase, not just from the safety aspect but also the fact that buying from a dealer enables you to hear the product before you buy it.
I bought mine from Tony of Coherent Systems who agreed to bring a Puresound A30 to my house to hear in my own listening environment with my speakers, a pair of slim and elegant yet puncy Piega TS5s. I was satisfied that the A30 in stock form was able to drive them easily and so it stayed put when he left, replacing a Densen B330 solid state amplifier costing £3000. The valve amp costing just over a third of the price was already proving to be more involving and enjoyable to listen to in the context of my own system. Good as the Densen amp is, it does a far better job in an all-Densen system than in my mongrel set-up.
The Puresound didn't exert the same vice-like grip over the bass of the Piegas as the Densen but this proved to be an actual improvement to my ears in that bass sounded more natural, tuneful and rhythmic; low notes were now given the chance to tell their full story and not just how their lives had abruptly begun. Music with any kind of rhythm took on more of a bouncy quality that didn't just make you tap your feet but actually want to get up and dance. The midrange was also clearer, more natural and overall coherence was much improved. My wife Tasha was also beginning to actually sit down and listen to music for the first time in her life rather than just have it playing in the background while she was either in her car driving or at home doing the ironing.
If there was a downside it was that the upper frequencies, whilst more extended now, did have a slightly glassy quality and the amp seemed to need to be turned up a bit before it had any real drive. It wasn't really the last word in transparency or dynamics either but for its price you could more than forgive these relatively minor shortcomings. I'd say it certainly wiped the floor quite convincingly with just about every other commercial amplifier up to and above the £1000 mark. It was fun, involving and enjoyable and had great timing acuity even if it didn't quite yet have that tingle factor to make the hairs on your arms and neck stand up. It could certainly play music and put a big smile on your face though.
I enjoyed this amp in stock form for the month of April this year until I took it to Anthony's in South Wales where it was to undergo extensive modification as planned from the outset. Whatever was to happen from this point on, I'd had plenty of time to get to know the original, unmodified Puresound A30 and would therefore be in a much better position to appreciate the changes Anthony was going to bring to it.
During the month that the amp was at Anthony's I had on loan his baby Copper amp to keep me going. It was more transparent and dynamic than the Puresound A30 but then it should be considering its complete set of NOS valves including GEC KT88s, quality bespoke transformers, a copper chassis eliminating eddy currents and point-to-point wiring throughout in place of PCBs. It was perhaps a little forward and slightly brittle sounding at times but I'd like to attribute that to an impedance mismatch; the output transformers are wound to see a 6.8 ohm load and the Piagas are a nominal 4 ohm.
On the whole, if the Puresound post-modification was to be nearly as good as this Copper amp it would certainly have been worthwhile. The modifications included changing all the valves from Electro Harmonix 6550s to Svetlana Cryo-treated KT88s, the Chinese driver valves were replaced with Philips JAN 6SN7s and the Chinese rectifier valves were replaced with NOS Mullard GZ34s. The volume circuitry was removed along with input selection and signal paths were shortened. The circuit was also was altered to optimise the output transformers more with the aim of improving dynamics and resolution. Finally the Triode/Ultra Linear switches were removed from the circuit path with the amp set permanently to UL mode.
Cosmetically a black acrylic sheet replaced the front panel that used to house the now-redundant volume and input selector knobs. In all the mods cost a shade under £700 including valves, parts and labour.
The amp returned home as the Tube Distinctions AOS classic series (to commemorate the Art of Sound Forum) and I was eager to hear if my gamble had paid off. First impressions suggested more drive, articulation and texture in the bass than even the Copper amp, never mind when it was the unmodified Puresound A30. Dynamics and detail seemed better across the board and the amp seemed to have guts even at lower volumes whilst sounding more at ease and less strained at higher volume levels.
However, within a few days I noticed that the amp was sounding rather fatiguing. There was a relentless shrillness to upper frequencies that were beginning to set my teeth on edge. I was assured that this was part of burn-in but what if it was never going to go away? Meanwhile how am I going to burn in my new amp if it sounded so unpleasant? This shrillness wasn't noticeable initially but now I knew it was there it wasn't something I could tolerate for any length of time. I found myself wincing instead of tapping my feet.
Perhaps a spot of tube rolling would ease the pain and make it more pleasant to listen to so Anthony agreed to send me a pair of Mullard GZ32s to put in place of the GZ34s as they have a somewhat 'darker' tonal characteristic. It was also suggested that the Philips JAN 6SN7s had a rather forward sounding treble and these may well be the culprits, so a set of Electro Harmonix 6SN7s were sent for me to try. Before these valve alternatives had even arrived the shrillness was already beginning to fade, albeit slowly so I felt encouraged that I hadn't made a big mistake.
I did wonder how these tonal changes, both with different valves and with burn in were possible given that the amp measured ruler-flat from 4 to 100,000 Hz. Perhaps they are something some of us just imagine... Perhaps there is more to tonality than frequency curves. Pehaps it has more to do with distortion characteristics at given frequencies than with output....
Anyway, I tried the GZ32s and they seemed just to sound duller in comparison so the GZ34s were promptly put back in. I used two Céline Dion tracks, That's the way it is and The first time ever I saw your face to make my comparisons because the music is familiar, the recording quality is good and I would more easily get a second opinion from Tasha who is a big Céline fan. This was to be her first A/B/X dem swapping the Philips JAN 6SN7s for the Electro Harmonix versions.
On some of the higher notes/louder passages that Céline sings there was a degree of harshness that Tasha commented on. With the EHs this effect was lessened somewhat and her voice sounded more pleasant. Tasha noted this change with ease. I then swapped the JANs back in and asked her what she thought overall. My own views were that the EHs had got rid of the harshness by killing the dynamics and the tune. The first time ever I saw your face is a ballad that sets your hairs on your arms standing on end, especially when the violins join in at the point when she sings at full tilt. It just wasn't happening with the EHs. It just sounded easy to listen to, dull and lifeless all at the same time. I'd made my mind up. Interestingly, Tasha agreed with me. I always believed that she just followed the vocals but she said that she was listening to the whole music and it was more enjoyable overall with the JANs in place.
Over the next few days the harshness further faded and the amp completed the transition from initially impressive/ultimately fatiguing to acceptable and then onto wow, this sounds absolutely gorgeous! The higher frequencies were taking on an extra level of refinement bringing better tunefulness, harmonics, decay and a bigger soundstage to the party. This amp was now exceptional. It had cost me just under £1800 in total but could well see off many a commercial amp up to the 5k mark. Many thanks to both Guy Sergeant and to Anthony for allowing this experiment to be undertaken. It has easily surpassed my expectations to become probably the best sounding amplifier I've heard.
And it's mine! :)
The problem with the Yaqin was that it needed a step-down transformer to work safely with UK voltages and I didn't fancy this option. As good as the Yaqin sounded, the mains transformers are wound for 220 volt not the 240 for the UK where voltages have been known to push towards the 250 mark. Hook up a Yaqin or some other Chinese import here and you may get the fireworks to accompany your music before the music stops. This has already happened to at least one person...
Our resident electronics engineer and valve specialist Anthony even advised not to even switch such an amp on until someone like himself had had a good look at it and made sure it was safe. Thus from a purely safety angle my only option if I wanted a Chinese-built valve amp was to go for one with mains transformers specified for the UK. Two options sprang to mind: something from Prima Luna or the Puresound amps imported and made safe by Guy Sergeant based on but quite different to the Bewitch available for about the same money as the Yaqin. Ok, for the luxury of made-for-UK reassurance I was paying £1100 instead of under £400. Some of the price difference obviously included distributor and dealer mark-ups but I think this was definitely one instance where such middle men were adding value to my purchase, not just from the safety aspect but also the fact that buying from a dealer enables you to hear the product before you buy it.
I bought mine from Tony of Coherent Systems who agreed to bring a Puresound A30 to my house to hear in my own listening environment with my speakers, a pair of slim and elegant yet puncy Piega TS5s. I was satisfied that the A30 in stock form was able to drive them easily and so it stayed put when he left, replacing a Densen B330 solid state amplifier costing £3000. The valve amp costing just over a third of the price was already proving to be more involving and enjoyable to listen to in the context of my own system. Good as the Densen amp is, it does a far better job in an all-Densen system than in my mongrel set-up.
The Puresound didn't exert the same vice-like grip over the bass of the Piegas as the Densen but this proved to be an actual improvement to my ears in that bass sounded more natural, tuneful and rhythmic; low notes were now given the chance to tell their full story and not just how their lives had abruptly begun. Music with any kind of rhythm took on more of a bouncy quality that didn't just make you tap your feet but actually want to get up and dance. The midrange was also clearer, more natural and overall coherence was much improved. My wife Tasha was also beginning to actually sit down and listen to music for the first time in her life rather than just have it playing in the background while she was either in her car driving or at home doing the ironing.
If there was a downside it was that the upper frequencies, whilst more extended now, did have a slightly glassy quality and the amp seemed to need to be turned up a bit before it had any real drive. It wasn't really the last word in transparency or dynamics either but for its price you could more than forgive these relatively minor shortcomings. I'd say it certainly wiped the floor quite convincingly with just about every other commercial amplifier up to and above the £1000 mark. It was fun, involving and enjoyable and had great timing acuity even if it didn't quite yet have that tingle factor to make the hairs on your arms and neck stand up. It could certainly play music and put a big smile on your face though.
I enjoyed this amp in stock form for the month of April this year until I took it to Anthony's in South Wales where it was to undergo extensive modification as planned from the outset. Whatever was to happen from this point on, I'd had plenty of time to get to know the original, unmodified Puresound A30 and would therefore be in a much better position to appreciate the changes Anthony was going to bring to it.
During the month that the amp was at Anthony's I had on loan his baby Copper amp to keep me going. It was more transparent and dynamic than the Puresound A30 but then it should be considering its complete set of NOS valves including GEC KT88s, quality bespoke transformers, a copper chassis eliminating eddy currents and point-to-point wiring throughout in place of PCBs. It was perhaps a little forward and slightly brittle sounding at times but I'd like to attribute that to an impedance mismatch; the output transformers are wound to see a 6.8 ohm load and the Piagas are a nominal 4 ohm.
On the whole, if the Puresound post-modification was to be nearly as good as this Copper amp it would certainly have been worthwhile. The modifications included changing all the valves from Electro Harmonix 6550s to Svetlana Cryo-treated KT88s, the Chinese driver valves were replaced with Philips JAN 6SN7s and the Chinese rectifier valves were replaced with NOS Mullard GZ34s. The volume circuitry was removed along with input selection and signal paths were shortened. The circuit was also was altered to optimise the output transformers more with the aim of improving dynamics and resolution. Finally the Triode/Ultra Linear switches were removed from the circuit path with the amp set permanently to UL mode.
Cosmetically a black acrylic sheet replaced the front panel that used to house the now-redundant volume and input selector knobs. In all the mods cost a shade under £700 including valves, parts and labour.
The amp returned home as the Tube Distinctions AOS classic series (to commemorate the Art of Sound Forum) and I was eager to hear if my gamble had paid off. First impressions suggested more drive, articulation and texture in the bass than even the Copper amp, never mind when it was the unmodified Puresound A30. Dynamics and detail seemed better across the board and the amp seemed to have guts even at lower volumes whilst sounding more at ease and less strained at higher volume levels.
However, within a few days I noticed that the amp was sounding rather fatiguing. There was a relentless shrillness to upper frequencies that were beginning to set my teeth on edge. I was assured that this was part of burn-in but what if it was never going to go away? Meanwhile how am I going to burn in my new amp if it sounded so unpleasant? This shrillness wasn't noticeable initially but now I knew it was there it wasn't something I could tolerate for any length of time. I found myself wincing instead of tapping my feet.
Perhaps a spot of tube rolling would ease the pain and make it more pleasant to listen to so Anthony agreed to send me a pair of Mullard GZ32s to put in place of the GZ34s as they have a somewhat 'darker' tonal characteristic. It was also suggested that the Philips JAN 6SN7s had a rather forward sounding treble and these may well be the culprits, so a set of Electro Harmonix 6SN7s were sent for me to try. Before these valve alternatives had even arrived the shrillness was already beginning to fade, albeit slowly so I felt encouraged that I hadn't made a big mistake.
I did wonder how these tonal changes, both with different valves and with burn in were possible given that the amp measured ruler-flat from 4 to 100,000 Hz. Perhaps they are something some of us just imagine... Perhaps there is more to tonality than frequency curves. Pehaps it has more to do with distortion characteristics at given frequencies than with output....
Anyway, I tried the GZ32s and they seemed just to sound duller in comparison so the GZ34s were promptly put back in. I used two Céline Dion tracks, That's the way it is and The first time ever I saw your face to make my comparisons because the music is familiar, the recording quality is good and I would more easily get a second opinion from Tasha who is a big Céline fan. This was to be her first A/B/X dem swapping the Philips JAN 6SN7s for the Electro Harmonix versions.
On some of the higher notes/louder passages that Céline sings there was a degree of harshness that Tasha commented on. With the EHs this effect was lessened somewhat and her voice sounded more pleasant. Tasha noted this change with ease. I then swapped the JANs back in and asked her what she thought overall. My own views were that the EHs had got rid of the harshness by killing the dynamics and the tune. The first time ever I saw your face is a ballad that sets your hairs on your arms standing on end, especially when the violins join in at the point when she sings at full tilt. It just wasn't happening with the EHs. It just sounded easy to listen to, dull and lifeless all at the same time. I'd made my mind up. Interestingly, Tasha agreed with me. I always believed that she just followed the vocals but she said that she was listening to the whole music and it was more enjoyable overall with the JANs in place.
Over the next few days the harshness further faded and the amp completed the transition from initially impressive/ultimately fatiguing to acceptable and then onto wow, this sounds absolutely gorgeous! The higher frequencies were taking on an extra level of refinement bringing better tunefulness, harmonics, decay and a bigger soundstage to the party. This amp was now exceptional. It had cost me just under £1800 in total but could well see off many a commercial amp up to the 5k mark. Many thanks to both Guy Sergeant and to Anthony for allowing this experiment to be undertaken. It has easily surpassed my expectations to become probably the best sounding amplifier I've heard.
And it's mine! :)