Tube Preamps- Hard to decide, Input Welcomed

[ecir38]

A GSG side note, try the 5691 in place of the 6SL7, let me know your opinions. It sound really good to me.

Which 5691 did you try?

[tubes4hifi]

I've been thru at least a dozen preamps just this past year, trying to find the best combination of price & performance, these are my humble opinions, rated by price . . .

Dyna PAS3 - OK only if you replace most parts, disconnect all tone
controls and switches, and replace the selector switch.
Foreplay - the one I heard was fully modded $500+ and sounded awful.
VTA SP6 - yes, this is the one I sell, and I really like it, and so do my customers
CJ PV5 - a very nice upgrade and package compared to the Dyna
CJ PV8 - very very nice but still a real simple 70s circuit
Transcedence Grounded Grid - about $200 in parts, but a nice kit for
$500, and it does sound very good, but get the attenuator and better
caps
AIKIDO - I was amazed, absolutely best tube preamp I've ever heard,
IMHO as good as $5000 Convergence SL1
also BTW, neither me nor my customer liked their attenuator
Hagtech Clarinet & Cornet - a good deal if you don't need more than a
PCB and some parts, they sound good
CJ PV12 - not bad but not worth $800, simple circuit with complex power
supply that corrupts the sound IMHO
ARC SP6 & SP8 - both overpriced classics, take the 6, it's better than the
8, I knew someone who paid $1000 for an SP8 and then bought my
SP6 'cause it sounded better
here's some links to photos of the SP6 and the AIKIDO I've built
www.tubes4hifi.com/pre3.htm
www.tubes4hifi.com/pre1.htm

[lth1]

ecir38: I used a Philips 1970's 5691.

tubes4hifi: I completely agree with your comments on the AIKIDO preamp. I see that you used the 9 pin version, what tubes did you actually end up using? I have all three boards, have only built so far the mono octal version, using 6SN7 tubes, also the attenuator. This preamp is on a test bed driving a GSG amp.

On your comment on John's attenuator, what did you not like; the awkward configeration or the sound or both. This preamp is for my daughter but I will not end up using the AIKIDO attenuator in the final preamp due to its awkward and hard to get use to design, but actually a good inexpensive attenuator.

[CpuZapper]

Hello Tubes4hifi, thanks for the great post.

The Aikido sounds like a clear winner at a cost of around $110.00 for Christmas. I have read good things about it but I don't ever remember it being compared to a $5000.00 preamp, if I read your post correctly.

The 9 pin version sure sounds flexible, did you stay with the four 6CG7's or try any of the other combinations of 9 pin tubes?

The Phono Dude, was it the updated circuit from 24-5-2006 or the version 4 from 2004? Also did you try other tubes than the 5755/5751 combination?

The cost of tubes is what stops or diverts me in different or wrong directions. Your recommendations will be appreciated.

Thanks, egilbert.

[tubes4hifi]

I didn't get around to trying the 6FQ7s although I'm sure they'll be even better than the cheap EH 12AU7s I used. I also built a 2nd one using the OCTAL board with 6SN7s and it is even better, I hope to take some photos and post them on my site within a few days. I went with a much more complex power supply since without adding a phono board I had more room inside the chassis. Give me a day or two then check this page
www.tubes4hifi.com/A2.htm
The AIKIDO attenuator just didn't have enough range, although I admit I built it using 1db steps instead of 2db step, but even so, you would have to make large 12 db steps to get into the correct range, then 2db steps to fine tune. Now the 24 step attenuator on my Grounded Grid I absolutely love it, the step size is correct, and it's full range, all in one control.
You can buy Chinese copies for about $50 on ebay.
About the PhonoDude phono section, I used the 5755 and a 12AX7, and I was amazed how dead quiet it was, I've never had much good luck with a phono stage before. It was the newer 2006 version as far as I know, since I bought it directly from Germany this year. If anyone needs any 5755 tubes I've got an extra dozen of them. I did find 2 bad ones (noise & microphonic) from the first 6 I bought.
Also for new DIYers, please remember that building a low cost preamp is a great way to save money, but just because the PCB kit is $140 or whatever, if you want a nice finished product it's probably going to cost a total of $4-600 by the time you add a chassis, all the controls, power supply, etc. The link to my SP6 page in the previous post is an example of how those costs can add up.
Also I'm looking for EXPERIENCED builders who would like to help others get a nice preamp at a decent price. I get several requests each month to put an SP6 or AIKIDO together but I don't have the time, as I do work a regular full time 50 hour job plus another 20 hours on this tube hobby, so if you've sucessfully build low-noise preamps, and like drilling holes and soldiering parts, and could use an extra $200 for a project, let me know!

[CpuZapper]

Hi Tubes4hifi, I was wondering where you bought the power supply boards or did you have them made?

[John123]

I use these. [url]http://www.elektronky.vyjimecny.cz/?p=p_19&sName=předzesilovače[/url]

[EWBrown]

I found from experience that I didn'tlike the "foreplay" sound with the C4S boards in place of the VA plate and CF cathode resistors. I tried all of the "fancy" mods and went back to (almost) the basics...

I've built one of the FPIIs more or less "stock" with the only mod being a better power tannie than the original cheap little "Allied" 125VAC 15 mA / 6.3VAC @ 600 mA. trannie. I used 125-0-125 @ 25 mA and 6.2V @ 1.2A, that gave me better / cleaner B+ (around 165VDC) and the filament winding had enough "juice" so tthat I could rectify the 6.3VDC.
Some 12AU7s sounded harsh (especially lower cost imports) I found the best were NOS RCA cleartops and some vintage well-used Telefunken ECC82s. Also 5963s worked well. Didn't try 12BH7s or 6CG7s.

Later on, I built up an FP III, with some mods added during the buld, I skipped the cheap little 11 position series attenuators and went with one of the Hong Kong 2 X 100K, 4 position ladder attenuators, and skipped the multiple input selector, just one pair of inputs, one pair of outputs.
Also I used 6SN7s in place of 12AU7s. Much better....

Next line stage will be the Aikido, in octal version. this is a work in progress, though at a rather leisurely pace at present...

/ed B in NH

[wiredbecker]

I'm just using my computer and itunes as my preamp right into the ST35 and then the A25XLs. It sounds amazing.

I have a very, very clean PAS that I managed to finagle a trade for from a guitar shop that was going out of business. Haven't started bringing it up on the variac yet.