I think you're absolutely right ... I'm in love with my Treasure CV181-Z .... a tube with this performance with a lower gain I do not know 'if I could promote it
Do you have any idea .... ZM?
this is my pre-built self.
Simple common cathode.
Plate loaded by an autotransformer with 50% output. Built by Ciro Marzio (the author of Euridice preamp).
the fixed polarization in my case is obtained with a series of green leds (preferred to simple R and also to R + cap)
the tubes are the Treasure I talked about mounted on Teflon sheet.
the filaments are in AC in series at 12V. In input i use the Lightspeed as attenuator
Power supply is obtained with 5Y3 + CLC. All caps are made on polypropylene motorun. No electrolyte.
Great sound
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instead of LEDs in cathode , try 1K not bypassed with cap
that way you'll have lower feedback
if you have enough voltage from source , it's easy making cathode follower with same parts
I hope you're not using Lightspeed on output of that preamp ........ it is better having attenuator in front of it
that way you'll have lower feedback
if you have enough voltage from source , it's easy making cathode follower with same parts
I hope you're not using Lightspeed on output of that preamp ........ it is better having attenuator in front of it
thanks ZM
I specified that I use the LSpeed in input ..... I would never do it in out.
Cathode Follower ..... mmmhh ..... I hate them.
The R on the cathode .... certainly lowers the gain but I do not think significantly .... but I try.
my self-built DAC exits 2.5 v and the analog section has a buffer. Pilot the LSpeed very well.
I specified that I use the LSpeed in input ..... I would never do it in out.
Cathode Follower ..... mmmhh ..... I hate them.
The R on the cathode .... certainly lowers the gain but I do not think significantly .... but I try.
my self-built DAC exits 2.5 v and the analog section has a buffer. Pilot the LSpeed very well.
Agreed to both. ZM may disagree with my suggestion, but bascally I see 2 options that will minimally alter the sonic signature of your system:
- Add another LC140SS (you need a pair for stereo) in series with existing autoformer to make 4:1 ratio for minimal change of sonic signature (you will have noticeably more low end extension and a touch more high).
- Replace the autoformer with single ended to Line output Transformer. Something like the Lundahl LL1660 or a special order LL1680 gapped for 10 ma. A bit more change to sonic signature and output coupling capacitors are no longer needed (there is an option to retain them but I think you will prefer going without). This way you have the advantage of different ratios to choose from and galvanic isolation that usually has less noise and hum.
avinunca.....have no doubts ..... build it.
you will be rewarded ..... it is a superior class device
nothing to disagree with - both clean solutions ...... not attenuation but transformation
I just shunned idea of any way of additional attenuation or additional xformer
for clearing dilemma or two ....... just make simple test , with any volume pot you have around , say 10Klog
route your source via pot directly in SissySIT and hear do you have enough SPL
if yes , any gain in line stage is practically decreasing sound quality , due to necessary over-attenuation
practically , even when 0db gain is OK/enough ,if you introduce 3 to 6db in line stage , things are still OK , regarding gain structure
edit: of course that you can measure what's practical gain of your existing line stage , to add few more details in picture
route your source via pot directly in SissySIT and hear do you have enough SPL
if yes , any gain in line stage is practically decreasing sound quality , due to necessary over-attenuation
practically , even when 0db gain is OK/enough ,if you introduce 3 to 6db in line stage , things are still OK , regarding gain structure
edit: of course that you can measure what's practical gain of your existing line stage , to add few more details in picture
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Aaah , the venerable Leak Stereo 20 = this was my carrot into the rabbit hole of high fidelity and DIY. I was given a loaner from audiophile and later managed to source a poorly treated one for myself which I then restored.
But onto current things
Such a beautiful thing to behold - finally took the time to read everything again carefully and assembled the boards. Thanks ZM for all the carefully marked packets and direction.
Had to change plans for installation, originally planned on mounting board flush to the heatsinks - but the cinemags would have caused problems for the speaker binding posts and thus bought a L-bracket ( 4mm was all I could find locally ) and mounted the boards
= power supply is tested and working as hoped but after all the cursing to get the brackets mounted, I opted for a beer and another day for testing.
slowly but surely, I will soon have the pleasure of music. ..dB
I did repeated tests between yesterday and today to compare the introduction or removal of the preamp.
in practice removing the pre does not involve any sacrifice both in terms of signal integrity and SPL. so I'll put the pre aside and leave my Lightspeed between DAC and Sissy.
but among my tubes I also own a 12B4A (RCA) that has a very low gain ..... it will be appropriate to do some experiment
Dear dB:
With reference to the picture of your SissySIT boards in post #295, what are the connectors you are using, are they all Molex KK ?
Have been looking around for board connectors and have come across those ... do you already have experience in using these for power and speaker connections, as opposed to only for signal input ?
Very interesting ... so far, I was only thinking of using 6,35 mm spades for power, and maybe for speaker out as well ...
Best regards,
Claas
With reference to the picture of your SissySIT boards in post #295, what are the connectors you are using, are they all Molex KK ?
Have been looking around for board connectors and have come across those ... do you already have experience in using these for power and speaker connections, as opposed to only for signal input ?
Very interesting ... so far, I was only thinking of using 6,35 mm spades for power, and maybe for speaker out as well ...
Best regards,
Claas