No I guess.
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Topping Pre90 Review (preamplifier)
- Thread starter amirm
- Start date
I am not familiar with the output stage of my X26 pro. It means it is not capacitive and not capped ?
Hey there everyone and cheers Amir for the work.
I am heavily thinking about using this Topping Pre90 to feed the Purifi 1ET400A directly (e.g. I would get VTV's "EVAL build", which mimicks Bruno's EVAL build, which Amir tested to be outstanding and more particularly so without the pre-gain stage of the OPamp).
On the voltage side it seems this is fine: Amir sees excellent results on the Topping Pre90 all the way up to 8Vrms (I would be using balanced XLR in/out everywhere too) and even though this has not been tested, I would assume that you can go up to 15Vrms on the Topping's output without loosing much of what makes that preamp a transparency champ. Nominally, with balanced in/out, this preamp is advertised to go all the way up to 50Vrms if my memory is not failing me.
Question is the impedances. I have basic electronics understanding but little experience plugging audio devices together in such non standard ways. Is there anyone around here which could give an informed opinion on whether it would really make sense to wire the Topping Pre90's balanced output to a Purifi 1ET400A directly (bypassing the pre-gain stage of the EVAL build) ?
(Before people ask: yes, I need that preamp because of switching sources and also because the DAC I use does not have volume control nor any form of added preamplification)
Reaaally appreciate you guys providing input on this. I have a feeling I'm not the only one willing to try this, on the basis that working with high voltages as early as possible is always the best thing to do. This preamp + bypassed-amp setup seems to me like it would be a nice poor man's version of a Pre90 + Benchmark AHB2 combination (which again Amir notes could be special interest since in low-gain mode the Benchmark would be fully driven with ~8Vrms, which the Topping Pre90 has no problem delivering).
EDIT: I have actually asked VTV about this and all they say is that - yes, you can bypass the OPamp's pre-gain stage on their Eigentakt-EVAL build but - they advise you not to do this bypassing. When asked why, they answer that the low input impedance of the 1ET400A alone could be problematic. Now of course, it's not that I absolutely want to be the rogue kid who doesn't listen here, but there's also the fact that from VTV's manufacturing standpoint *of course* they discourage you to do that (firstly, if one does not need a pre-gain, things start to look more and more straightforward on the DIY side when thinking about combining a powerful preamp with the Purifi modules and, secondly, it's a manufacturer's recommendation ... of course that consists in saying "don't do weird stuff with our products / you should use it as such because it is designed as such to not generate any problems", etc.). This all tells me that maybe it is nonetheless a very sensible thing to do (and maybe even a good thing) to wire the Pre90 to the Purifi modules directly
. Again, comments welcome.
I am heavily thinking about using this Topping Pre90 to feed the Purifi 1ET400A directly (e.g. I would get VTV's "EVAL build", which mimicks Bruno's EVAL build, which Amir tested to be outstanding and more particularly so without the pre-gain stage of the OPamp).
On the voltage side it seems this is fine: Amir sees excellent results on the Topping Pre90 all the way up to 8Vrms (I would be using balanced XLR in/out everywhere too) and even though this has not been tested, I would assume that you can go up to 15Vrms on the Topping's output without loosing much of what makes that preamp a transparency champ. Nominally, with balanced in/out, this preamp is advertised to go all the way up to 50Vrms if my memory is not failing me.
Question is the impedances. I have basic electronics understanding but little experience plugging audio devices together in such non standard ways. Is there anyone around here which could give an informed opinion on whether it would really make sense to wire the Topping Pre90's balanced output to a Purifi 1ET400A directly (bypassing the pre-gain stage of the EVAL build) ?
(Before people ask: yes, I need that preamp because of switching sources and also because the DAC I use does not have volume control nor any form of added preamplification)
Reaaally appreciate you guys providing input on this. I have a feeling I'm not the only one willing to try this, on the basis that working with high voltages as early as possible is always the best thing to do. This preamp + bypassed-amp setup seems to me like it would be a nice poor man's version of a Pre90 + Benchmark AHB2 combination (which again Amir notes could be special interest since in low-gain mode the Benchmark would be fully driven with ~8Vrms, which the Topping Pre90 has no problem delivering).
EDIT: I have actually asked VTV about this and all they say is that - yes, you can bypass the OPamp's pre-gain stage on their Eigentakt-EVAL build but - they advise you not to do this bypassing. When asked why, they answer that the low input impedance of the 1ET400A alone could be problematic. Now of course, it's not that I absolutely want to be the rogue kid who doesn't listen here, but there's also the fact that from VTV's manufacturing standpoint *of course* they discourage you to do that (firstly, if one does not need a pre-gain, things start to look more and more straightforward on the DIY side when thinking about combining a powerful preamp with the Purifi modules and, secondly, it's a manufacturer's recommendation ... of course that consists in saying "don't do weird stuff with our products / you should use it as such because it is designed as such to not generate any problems", etc.). This all tells me that maybe it is nonetheless a very sensible thing to do (and maybe even a good thing) to wire the Pre90 to the Purifi modules directly
. Again, comments welcome.
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The Gustard sounded great to me connected to my pre90. I connected both a Benchmark DAC3B (no volume) and Gustard X26 Pro mostly via RCA and they both sounded great. I did also try XLR's from both DACs into the pre90 and it was also fine. I had a Benchmark HPA4 that I compared the pre90 to and they both sounded the same. I also no longer needed the headphone amp on the HPA4 because I only listen to RAAL SR1a headphones and those do not use traditional headphone jacks. I sold the HPA4 and use the pre90 with my Benchmark AHB2 mono and XLR connections to a Topping D90SE DAC and RCA to a Sony FM tuner.
My only complaint with the pre90 is that on my office system the pre90 did not sound good with my CODA #8 amp. Not a big deal because I had a different preamp for that amp.
I have 2 preamps now (sold the HPA4). I for each system because I do not like digital volume controls (such as on the Gustard). I also have multiple analog pieces for both of my systems, SACD player, 2 tuners.
My only complaint with the pre90 is that on my office system the pre90 did not sound good with my CODA #8 amp. Not a big deal because I had a different preamp for that amp.
I have 2 preamps now (sold the HPA4). I for each system because I do not like digital volume controls (such as on the Gustard). I also have multiple analog pieces for both of my systems, SACD player, 2 tuners.
Hey there and cheers for answering yyzsb. So just to be clear, you have actually experimented (positvely) the full DAC + Pre90 + PowerAmp chain, and saw no flaws. I find this reassuring, although it does not 100% take away my concerns. This is because the AHB2 has a decently high input impedance (50k / 1M), so of course no problems are to be expected. The Purifi modules (1ET400A), when plugged directly to a pre-amp (no input buffer board in front), present a much lower input impedance and that's what worries me.
On paper, Topping says that the Pre90 will have no issue driving loads with input impedances as low as 600Ohms and maybe even less, so one should be fine with the standalone Purifi's (which are in the 2k range I think), but in practice I wonder how well this holds. There's also a difference between being able to drive a load and being able to drive it in a way that does not cause voltage deformation in the signal.
Bottom line: still looking for inputs here
On paper, Topping says that the Pre90 will have no issue driving loads with input impedances as low as 600Ohms and maybe even less, so one should be fine with the standalone Purifi's (which are in the 2k range I think), but in practice I wonder how well this holds. There's also a difference between being able to drive a load and being able to drive it in a way that does not cause voltage deformation in the signal.
Bottom line: still looking for inputs here
The pre90 + Gustard X26 Pro + BEnchmark DAC3B + AHB2 sounded great. Just as good as the Benhcmark HPA4 in place of the pre90.
The pre90 + Gustard X26 Pro + Benchmark DAC3B + CODA #8 did not sound good. It was dull and lifeless. I had sold the HPA4 so never compared with the CODA. Though I have been told a a few pro users (I imagine recording engineers) use the HPA4 + CODA #8 combo.
The Gustard X26 Pro is a bit flakey with direct to amp (no preamp) usage. It sometimes makes a popping sound on the speakers. Just once, per listening session and it does not happen all the time. This is my second Gustard X26 Pro (replaced under warranty) that does this. Not a concern for me, as I stated before I hate DAC direct to amp. I need a preamp. I do love the Gustard X26 Pro which is not as detailed as my Benchmark DAC3B but as other attributes that I like.
Have you read this review:
Topping Pre90 + Ext90 Review - Pre-amp my Power-amp! (soundnews.net)
The pre90 + Gustard X26 Pro + Benchmark DAC3B + CODA #8 did not sound good. It was dull and lifeless. I had sold the HPA4 so never compared with the CODA. Though I have been told a a few pro users (I imagine recording engineers) use the HPA4 + CODA #8 combo.
The Gustard X26 Pro is a bit flakey with direct to amp (no preamp) usage. It sometimes makes a popping sound on the speakers. Just once, per listening session and it does not happen all the time. This is my second Gustard X26 Pro (replaced under warranty) that does this. Not a concern for me, as I stated before I hate DAC direct to amp. I need a preamp. I do love the Gustard X26 Pro which is not as detailed as my Benchmark DAC3B but as other attributes that I like.
Have you read this review:
Topping Pre90 + Ext90 Review - Pre-amp my Power-amp! (soundnews.net)
headphoneuser123
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Would the smsl su-9 work with the input impedence of the pre90?
Was curious if anyone thinks the Pre90 would pair well with the Denafrip ares 2? I've read reviews where they say...never actually listening 2 but I assume going by measurements, that..yes they would match nicely. But...knowing my limitations on this subject..I contacted both Topping and Denafrip and asked this very question. They both basically said NO. Just wondering what I'm missing here. I'm assuming they were going by impedance matching. Not sure what else to look at. I have a pair of active speakers(ae1's) and have been looking for a balanced dac and small balanced preamp. Pre90 seemed to have fit the bill. I already have the topping d70s in my main 2 ch set up...and although I have nothing to compare it to, I'm enjoying what I'm hearing. Curious to know what the pre90 would bring to the table with the schiit bitfrost as well..but now my mind is wondering.
My Topping pre90 worked great with a Benchmark AHB2 and a KRELL K-300i integrated.
I was not good, lifeless and flat, with a CODA #8 amp.
It sounded good with the new LSA Voyager 350 GAN however, the granularity of the volume was non-existent. I am assuming a GAIN mismatch.
I would just get the Benchmark LA4. I sold my HPA4 and now wish I had it back. I got almost what I paid for in the sale. The Topping pre90 and HPA4 sounded the same on the AHB2. I never tried the HPA4 on the CODA #8 or LSA. However, I am almost certain there would not have been a problem. Benchmark gear is really well done.
I was not good, lifeless and flat, with a CODA #8 amp.
It sounded good with the new LSA Voyager 350 GAN however, the granularity of the volume was non-existent. I am assuming a GAIN mismatch.
I would just get the Benchmark LA4. I sold my HPA4 and now wish I had it back. I got almost what I paid for in the sale. The Topping pre90 and HPA4 sounded the same on the AHB2. I never tried the HPA4 on the CODA #8 or LSA. However, I am almost certain there would not have been a problem. Benchmark gear is really well done.
try to keep your source outpedance to 1/10 of the preamp, if not it might affect the power output or even frequency response of your dacTrying to wrap my head around the low impedance discussion.
Can someone enlighten me on what problems or things to look for with impedance ? Source to preamp and pre to power amp.
I didn't want to have to buy the LA4
Because the test was measured without the use of the volume control on the unit. So the noise from the differential amplifier stage is not attenuated when outputting 50mV.
And balanced output inherently is more noisy than SE output.
The actual 50mV SNR of pre90/a90 should be 105dB for RCA output, 102dB for XLR output.
From the top post on this thread:
FWIW, the Okto DAC8 Pro has a 200ohm output impedance.Suspecting some of the good noise figure comes at the expense of lower than normal input impedance, I jacked up the default 40 ohm output impedance of my Audio Precision analyzer to 200 ohm. The result was that the output from the Pre90 dropped down to 3.6 volts (instead of 4). One click on the volume control compensated for that nicely and give me the same good performance just as well:
So there is really no penalty to the lower input impedance.
I have both Denafrips Ares II and PRE90. Hooked them up via XLR to my NAD C298. The Ares II is being fed via USB from an Allo Usbridge Signature streamer.
Reading all these posts regarding input impedance of the PRE90 got me a bit worried.
Ares II has an output impedance of 1.25kohm via XLR and the PRE90 has 2.2kohm input impedance via XLR.
Will this DAC and preamp combo create a low pass filter on the input? Or the only "issue" would be that I have to turn the volume a few notches up?
But then there's the post that I quoted which basically says it all...
My ears didn't notice anything strange on the low end frequencies. What's more, after changing from Topping D70s to Ares II I feel like the bass region is more emphasized.
I still have some days left to return the PRE90 and not exactly sure what to do. Was thinking that more experienced folks over here can help shed some light on this matter. Maybe even JohnYang1997.
Shoaibexpert
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For the users of newer DACs e.g. SU-9 and the likes (acting as preamp) straight into power amplifiers...would a unit like in the chain like this be of any sonic benefit?
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