First impressions

[efung]

efung, again, thanks for the fantastic info. Is any generic (eBay) DC-DC converter adequate for isolating the ground plane? Do you have a product on the market?
NJM has been called "ghetto blaster" quality in the DIY community. Agree with the substandard sound quality. A few months ago I got a deal on Icepower modules 125ASX2. These were in VocoPro Feather amp FA-500 selling for $87 shipped in US clearance Beach Audio through NewEgg. The preamps in these were loaded with NJM op amps. Sound quality was substandard. Pulled the Icepower modules, trashed the rest of it.

hifinet, you can buy the DC-DC converter from mouser.com or digikey.com. The Japanese brand muRata is good. You can try the 2W module MEJ2; just search it on either mouser or digikey web page. The ICEpower 500A uses MC33078 quad opamp in the front end. The input is configured as difference input amplifier for XLR input. The MC33078 is a low-end BJT opamp. You can replace it with BJT input OPA1604. The OPA1604 has low noise and much lower distortion. Topping E30 uses BJT input OPA1612. It is better than OPA1602 and cost 2.5x. You have a pair of British made loudspeakers. You should avoid using FET input opamps like OPA2132. The reason is that Burr-Brown's FET input opamps enhance mid tone. I bought an excellent condition Nakamichi cassette deck DR-1 a few years ago. I recapped the electrolytic caps and replaced all the NJM opamps except the one for the headphone output with very good and pricey opamps. How do I use the cassette tape deck? Recording vinyl records!

[philrandal]

efung, again, thanks for the fantastic info. Is any generic (eBay) DC-DC converter adequate for isolating the ground plane? Do you have a product on the market?
NJM has been called "ghetto blaster" quality in the DIY community. Agree with the substandard sound quality. A few months ago I got a deal on Icepower modules 125ASX2. These were in VocoPro Feather amp FA-500 selling for $87 shipped in US clearance Beach Audio through NewEgg. The preamps in these were loaded with NJM op amps. Sound quality was substandard. Pulled the Icepower modules, trashed the rest of it.

hifinet, you can buy the DC-DC converter from mouser.com or digikey.com. The Japanese brand muRata is good. You can try the 2W module MEJ2; just search it on either mouser or digikey web page. The ICEpower 500A uses MC33078 quad opamp in the front end. The input is configured as difference input amplifier for XLR input. The MC33078 is a low-end BJT opamp. You can replace it with BJT input OPA1604. The OPA1604 has low noise and much lower distortion. Topping E30 uses BJT input OPA1612. It is better than OPA1602 and cost 2.5x. You have a pair of British made loudspeakers. You should avoid using FET input opamps like OPA2132. The reason is that Burr-Brown's FET input opamps enhance mid tone. I bought an excellent condition Nakamichi cassette deck DR-1 a few years ago. I recapped the electrolytic caps and replaced all the NJM opamps except the one for the headphone output with very good and pricey opamps. How do I use the cassette tape deck? Recording vinyl records!

Brings back old memories of when I replaced the electrolytic caps with low-esr versions in my old NAD 7020 receiver, and bypassed the PSU electrolytics with audio quality polypropylene caps. I also upgraded the op-amps at the same time.

But replacing non-polarised electrolytics in the crossover filter with high quality polypropylene capacitors in my old Mission 700 speakers was the single most impressive sound quality tweak I have ever made.

Cheers,

Phil

[hifinet]

efung:
I bought an excellent condition Nakamichi cassette deck DR-1 a few years ago. I recapped the electrolytic caps and replaced all the NJM opamps except the one for the headphone output with very good and pricey opamps. How do I use the cassette tape deck? Recording vinyl records!

I owned a Dragon in the late 80's. The best cassette deck ever. Had a Tascam as well. So maintaining the signal in analog is the way to go. But where do you get blank TDK or Maxell cassette tapes?

[hifinet]

philrandal wrote:

But replacing non-polarised electrolytics in the crossover filter with high quality polypropylene capacitors in my old Mission 700 speakers was the single most impressive sound quality tweak I have ever made.

Well worth the effort, if you can afford the polypropylene caps. Need to have a good surplus source. Occasionally found Rel-Caps for a decent price. This was a standard speaker crossover upgrade. Now it's DSP crossovers and Class D amps.

[efung]

efung:
I bought an excellent condition Nakamichi cassette deck DR-1 a few years ago. I recapped the electrolytic caps and replaced all the NJM opamps except the one for the headphone output with very good and pricey opamps. How do I use the cassette tape deck? Recording vinyl records!

I owned a Dragon in the late 80's. The best cassette deck ever. Had a Tascam as well. So maintaining the signal in analog is the way to go. But where do you get blank TDK or Maxell cassette tapes?

hifinet, Dragon has the best mechanical drive system; much lower wow & flutter. But, it is difficult to maintain. I made an offer to an Audiogon seller a few years ago to buy a Dragon with contingency that the deck must be fully functional. The seller did not come back to me. After that, I bought 2 DR-1 from ebay sellers. The DR-1 is easy to maintain and upgrade. I bought many FUJI ZII and DENON HD8 tapes from ebay a few years ago. These are type-II tapes. Denon HD8 is the best non-metal type. I have an Ortofon LOMC (0.09mV output) with a DIY 30x gain step up transformer. My tube phono EQ AMP is housed in a 2U steel chassis. In addition to the rotary input selector, I installed an old fashion flip switch for tape source input/monitor. Just for your information, if the design is done properly, modern delta-sigma DAC chip like PCM5122 and AK4493 grade can play back sound in detail almost as good as my analog playback system.

[hifinet]

efung

The ICEpower 500A uses MC33078 quad opamp in the front end. The input is configured as difference input amplifier for XLR input. The MC33078 is a low-end BJT opamp. You can replace it with BJT input OPA1604. The OPA1604 has low noise and much lower distortion. 

Haven't used SMDs before. I've seen the instructional videos by Dave Jones on YouTube. I don't have a stereo microscope, just a pair of loupes. Everything these days is SMDs, I guess it's time to step up.

efung

DIY 30x gain step up transformer

DIY as in wind your own?

[efung]

efung

The ICEpower 500A uses MC33078 quad opamp in the front end. The input is configured as difference input amplifier for XLR input. The MC33078 is a low-end BJT opamp. You can replace it with BJT input OPA1604. The OPA1604 has low noise and much lower distortion. 

Haven't used SMDs before. I've seen the instructional videos by Dave Jones on YouTube. I don't have a stereo microscope, just a pair of loupes. Everything these days is SMDs, I guess it's time to step up.

efung

DIY 30x gain step up transformer

DIY as in wind your own?

No, I did not. I bought them from ebay. Those were vintage transformers made for moving coil microphone in the old days. They were inexpensive 15 years ago. I searched it again today. They are expensive. If you type "vintage transformer microphone", you will find an inexpensive pairs with impedance ratio 200:49k, step up ratio is about 1:15. However, my pair is older than the Shure's.

[jonners]

Since this thread is entitled 'First impressions' I thought I would throw my SMSL Sanskrit 10th Mk2 DAC into the mix. It's playing through an Allo USBridge Sig, powered by an Allo Nirvana SMPS (which arrived today :-)
The sound is amazingly good. It's different to my Katana (with separate power supplies to each board) but not obviously worse except that perhaps the treble is a bit bright on some recordings. Since I only paid £75 for the Sanskrit that is very surprising to me. I'll have to do a lot more listening to come up with a preference.

[hifinet]

Since this thread is entitled 'First impressions' I thought I would throw my SMSL Sanskrit 10th Mk2 DAC into the mix. It's playing through an Allo USBridge Sig, powered by an Allo Nirvana SMPS (which arrived today :-)
The sound is amazingly good. It's different to my Katana (with separate power supplies to each board) but not obviously worse except that perhaps the treble is a bit bright on some recordings. Since I only paid £75 for the Sanskrit that is very surprising to me. I'll have to do a lot more listening to come up with a preference.

Is this with the default filter setting?

[jonners]

Since this thread is entitled 'First impressions' I thought I would throw my SMSL Sanskrit 10th Mk2 DAC into the mix. It's playing through an Allo USBridge Sig, powered by an Allo Nirvana SMPS (which arrived today :-)
The sound is amazingly good. It's different to my Katana (with separate power supplies to each board) but not obviously worse except that perhaps the treble is a bit bright on some recordings. Since I only paid £75 for the Sanskrit that is very surprising to me. I'll have to do a lot more listening to come up with a preference.

Is this with the default filter setting?

Yes, FL1 - sharp roll-off.