Off topic, but if you like the BA2018 Linestage, and you have not tried the ACP+ already to drive an F4, please do!
Different flavors, same great result!! Be sure to use the recommended Gold Caps on C3 for the ACP+. IMO, no other tweaks required to solicit a smile on your face driving the F4.
Different flavors, same great result!! Be sure to use the recommended Gold Caps on C3 for the ACP+. IMO, no other tweaks required to solicit a smile on your face driving the F4.
Yes,yes! Gain can be adjusted higher by changing R7 (33.2k to 47k or 68k). I have 98db speakers.
I have tried both the ACP+ (original BA2019 kit) and the BA2018 linestage with my F4, and I always come back to the BA2018 as the more harmonious pairing, at least to my ears, in my system ... speakers are 100 dB/W sensitive. 
For me, the ACP+ may give more warmth, but the BA2108 gives very attractive relaxed detail without losing a lot of warmth ... overall very neutral but musical.
For me, the ACP+ may give more warmth, but the BA2108 gives very attractive relaxed detail without losing a lot of warmth ... overall very neutral but musical.
simple as that:
- if you need invisible but ultra potent machine, with zero or moderate settable gain - Iron Pumpkin is for you
- if you need anything else, including some flavor ( part of it depending of type of volume attenuator you're going to use) , then that something else is for you
of course that IP can be used as superior selector/volume setting black box, and you can attach any preferred gain stage afterwards, to get more gain than IP is capable of and to get preferred flavor (2nd dominant, 3rd dominant, whatever)
- if you need invisible but ultra potent machine, with zero or moderate settable gain - Iron Pumpkin is for you
- if you need anything else, including some flavor ( part of it depending of type of volume attenuator you're going to use) , then that something else is for you
of course that IP can be used as superior selector/volume setting black box, and you can attach any preferred gain stage afterwards, to get more gain than IP is capable of and to get preferred flavor (2nd dominant, 3rd dominant, whatever)
I think I like the contribution of the autoformer iron in the signal, but I couldn't tell you exactly why. Never ran any distortion curves or anything, just threw it in there - listened - and it stayed.. BA2018 is a very low distortion piece with a nice low output impedance. Needed the extra gain so it seemed like it might be a good pairing.. R16/R17 adjustment would be simpler / cheaper / better measuring for more gain, but I'm just having fun with all this. I already had a Jensen transformer just sitting on an unused F6... so why not do something with it. Liked the result but curious about the Cinemag that gets mentioned.... bought it and here I am.
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(Be aware that these forums have eyes and ears built into the walls and they‘re all connected to ZM [emoji1782])
I‘d call that an advertisement and I’m falling for it!
This will count for another
„Just what you think you‘re doing, dave?“
Stop, Dave.... Just what do you think you're doing, Dave? - YouTube
Which I totally absolutely love [emoji2956]
„Just what you think you‘re doing, dave?“
Stop, Dave.... Just what do you think you're doing, Dave? - YouTube
Which I totally absolutely love [emoji2956]
well, sometimes I'm blatant, but I'm really trying not to be .... and I tried explaining differences
reason why I'm Omnipresent
- reading this thread is simple - I admire Wayne's work; it's always pleasure, besides being useful, to observe and investigate great engineering
I have tried both the ACP+ (original BA2019 kit) and the BA2018 linestage with my F4, and I always come back to the BA2018 as the more harmonious pairing, at least to my ears, in my system ... speakers are 100 dB/W sensitive.
For me, the ACP+ may give more warmth, but the BA2108 gives very attractive relaxed detail without losing a lot of warmth ... overall very neutral but musical.
I need to augment my post - Zen Mod's post #2347 made me realize that something else may also contribute to the peceived difference:
In the ACP+, I have the blue ALPS poti that came with the kit; Wayne's BA2018 I am using with a relay-based attenuator.
Best regards,
Claas
and I tried explaining differences
Omnipresent
Blatant or not, if your posts aren‘t [emoji1305], they’re either [emoji1303] or 🤌[emoji2532].
(My opinion ) so I’m very [emoji1317] and I‘ll stop here.
[emoji51]
[emoji317]
[emoji1781]
...
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I think discussing the attenuation solution is a very good point when thinking about sound of preamps in general and the BA2018 in particular ...
In my experience, my relay-switched resistor array-based preamps let through more detail than my ALPS-based preamps. But so far, I haven't been scientific about it and have not tried different attenuators in the same preamp.
As to the impedance of the pot - both the ALPS and the resistor arrays are 50k Ohm input impedance.
My sons and myself built one preamp with a 10k ALPS, and that is rather nice sounding, as well - but again, not tried different impedance pots in that circuit either, unfortunately.
In my experience, my relay-switched resistor array-based preamps let through more detail than my ALPS-based preamps. But so far, I haven't been scientific about it and have not tried different attenuators in the same preamp.
As to the impedance of the pot - both the ALPS and the resistor arrays are 50k Ohm input impedance.
My sons and myself built one preamp with a 10k ALPS, and that is rather nice sounding, as well - but again, not tried different impedance pots in that circuit either, unfortunately.
I had a (PEC Canada) 25k running for a very short time, sounded very promising but I swapped with a relay attenuator which is 10k, sounds very good too.
Depends the source, not the linestage AFAIK.
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