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Old 4th October 2012, 10:30 AM   #2051
palmas is offline palmas  Portugal
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Quote:
Originally Posted by mogliaa View Post
. 4P1L doesn't like currents below 20mA (check curves) so either the Hammond gapped for 30mA or the LL1660/20mA should work best. I just ordered from Thomas an LL1660/20mA so will report results soon
Ale
The LL1660/18 can be used for 30mA in 2.25:2+2
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Old 4th October 2012, 11:15 AM   #2052
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Originally Posted by massimo View Post
Yes please!
2nd the motion.


Mark
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Old 4th October 2012, 01:26 PM   #2053
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Hi Ale & All

Quote:
Originally Posted by mogliaa View Post
Thomas, can you share your experience with The tribute's OT?
earlier this year I discussed a lineoutput transformer with Pieter which should have it's secondary tapped as volume control. He initially wound a pair for me for a 10Y linestage runnign at 20mA. The ratio is 1:1 with 24 2dB taps.

Here are some photos:

VinylSavor: The Modular Preamplifier, Part 11: 10Y linestage

I will write a more detailed report about it within the next weeks

Obviously a integrated transformer/TVC has the advanatge of less parts in the signal path, while with separate transformer and AVC each can be optimized separately for it's task.

I borrowed both versions to a customer. He found that the tribute TVC has more dynamics compared to a spearate solutions, while the latter showed a better depth in teh soundstage. Both versions sound very good. The Tribute solution has teh dadvantage of less parts and a bit easier wiring.

I personally would prefer the tribute but will continue to have both variants in my offering.

Anybody interested in these can also contact me. I have an agreement with Pieter regarding sale of these. I will have several pairs by end of November. I can offer a pair for free trial to DIYaudio members. (Sorry for the commercial plug)

Best regards

Thomas
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Old 4th October 2012, 01:31 PM   #2054
palmas is offline palmas  Portugal
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Quote:
Originally Posted by Vinylsavor View Post
Hi Ale & All



earlier this year I discussed a lineoutput transformer with Pieter which should have it's secondary tapped as volume control. He initially wound a pair for me for a 10Y linestage runnign at 20mA. The ratio is 1:1 with 24 2dB taps.

Here are some photos:

VinylSavor: The Modular Preamplifier, Part 11: 10Y linestage

I will write a more detailed report about it within the next weeks

Obviously a integrated transformer/TVC has the advanatge of less parts in the signal path, while with separate transformer and AVC each can be optimized separately for it's task.

I borrowed both versions to a customer. He found that the tribute TVC has more dynamics compared to a spearate solutions, while the latter showed a better depth in teh soundstage. Both versions sound very good. The Tribute solution has teh dadvantage of less parts and a bit easier wiring.

I personally would prefer the tribute but will continue to have both variants in my offering.

Anybody interested in these can also contact me. I have an agreement with Pieter regarding sale of these. I will have several pairs by end of November. I can offer a pair for free trial to DIYaudio members. (Sorry for the commercial plug)

Best regards

Thomas
I would be very interested in trying one - what will be the price for a pair?
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Old 4th October 2012, 04:36 PM   #2055
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Hi!

I'm not sure if the forum rules allow to discuss prices of products. We can do that by PN

Thomas
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Old 5th October 2012, 07:13 AM   #2056
disco is offline disco  Netherlands
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Quote:
Originally Posted by mogliaa View Post
Yes, and me being a promoter of a great tube blamed to be very microphonic. 4p1L as a preamp is fantastic if properly used. Needs care on microphonics though. Filaments in parallel and starved at 500mA and easier for filament bias. 4P1L doesn't like currents below 20mA (check curves) so either the Hammond gapped for 30mA or the LL1660/20mA should work best. I just ordered from Thomas an LL1660/20mA so will report results soon
There is a multi-tapped secondary OT from Pieter which can provide dual function (OT and Volume control) in one. Apparently has had great feedback.
Thomas, can you share your experience with The tribute's OT?
Thanks
Ale
Ale,

Does starving filaments (in general) influence tube characteristics? I take it for granted the power limit goes down because of the diminished space charge...

Rgds, Jaap
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Old 5th October 2012, 07:47 AM   #2057
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Hi!

Quote:
Originally Posted by disco View Post
Does starving filaments (in general) influence tube characteristics?
rp goes up when starving filaments. How much depends on the tube.

Best regards

Thomas
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Old 5th October 2012, 10:28 AM   #2058
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I think there are various preferences for how much to starve the filaments. A colleague in London here uses 3.7v in series, and he says also Pearl tube coolers help cut down on microphonics. I haven't done any really detailed listening - I'm using 1.9v and 600mA generally. That would translate as 3.8v in series. Somewhere around 1.85-1.9v in parallel seems OK. Ale has been experimenting.
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Old 5th October 2012, 12:53 PM   #2059
mogliaa is offline mogliaa  United Kingdom
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Below 500mA (filaments in parallel) H3 and H5 increases significantly. Somewhere between 500-550mA will minimise microphony subject to your physical setup damping capability. You have to experiment yourself! Also adjusting current in the Coleman regulator is very easy...
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Old 5th October 2012, 01:17 PM   #2060
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Quote:
Originally Posted by Vinylsavor View Post
Hi Ale & All

earlier this year I discussed a lineoutput transformer with Pieter which should have it's secondary tapped as volume control. He initially wound a pair for me for a 10Y linestage runnign at 20mA. The ratio is 1:1 with 24 2dB taps.

Here are some photos:

VinylSavor: The Modular Preamplifier, Part 11: 10Y linestage

I will write a more detailed report about it within the next weeks

Obviously a integrated transformer/TVC has the advanatge of less parts in the signal path, while with separate transformer and AVC each can be optimized separately for it's task.

I borrowed both versions to a customer. He found that the tribute TVC has more dynamics compared to a spearate solutions, while the latter showed a better depth in teh soundstage. Both versions sound very good. The Tribute solution has teh dadvantage of less parts and a bit easier wiring.

I personally would prefer the tribute but will continue to have both variants in my offering.

Anybody interested in these can also contact me. I have an agreement with Pieter regarding sale of these. I will have several pairs by end of November. I can offer a pair for free trial to DIYaudio members. (Sorry for the commercial plug)

Best regards
Thomas
Hi Thomas

discussed this with Pieter (Tribute) around a decade ago when he told me about his idea to combine the TVC/AVC with the output transformer. Cool that you did it

The disadvantage is that you have no constant output impedance because it increases with increasing of the volume. In your configuration with ratio 1:1 you have the max. output impedance of tubes plate resistance - assume the source input from the next stage is large. So with high plate resistance of the 10Y you deal with high output imedances ...

Anyway, with short cables to the power amp you can ignore it - more or less.


Quote:
Originally Posted by Vinylsavor View Post
Hi!
I'm not sure if the forum rules allow to discuss prices of products. We can do that by PN
Thomas
You mentioned it and as manufacturer it would be helpful to discuss technology only and not brands.

BR, Joao
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